1. A propagation delay compensation circuit, comprising:

a first low pass filter configured to receive a digital input and reduce noise of the digital input including a measured angular position;

a first differentiator configured to receive a filtered digital input comprising the measured angular position and to calculate a velocity from a time difference of the measured angular position and a previous angular position;

a second low pass filter configured to reduce noise from the velocity;

a second differentiator configured to receive the filtered velocity and calculate an acceleration using a time difference of the filtered velocity and a previous velocity;

a third low pass filter configured to reduce noise of the acceleration; and

a delay compensator configured to receive the filtered digital input, the filtered velocity, and the filtered acceleration, and to calculate a propagation delay compensated digital output.

2. The propagation delay compensation circuit of claim 1, further characterized by comprising an extrapolation generator configured to receive the filtered acceleration and calculate an extrapolated angular position.

3. The propagation delay compensation circuit of claim 2, further characterized by comprising a pre-processing block configured to:

receiving the digital input comprising the measured angular position;

determining that the measured angular position is within an acceptable range and then sending the digital input including the measured angular position to a first low band pass filter; and is

Determining that the measured angular position is not within an acceptable range and then sending a digital input including the extrapolated angular position to the first low-band-pass filter.

4. The propagation delay compensation circuit of claim 2, further characterized by comprising a pre-processing block configured to:

receiving the digital input comprising the measured angular position;

determining that the digital input including the measured angular position is received and then sending the digital input including the measured angular position to the first low-band-pass filter; and is

Determining that the digital input including the measured angular position was not received, then sending the digital input including the extrapolated angular position to the first low-band-pass filter.

5. The propagation delay compensation circuit of claim 2, further characterized by comprising a pre-processing block configured to:

receiving the digital input comprising the measured angular position;

comparing the measured angular position to the extrapolated angular position for a best fit; and is

Sending the digital input including the best-fit angular position to the first low-band-pass filter.

6. A propagation delay compensation circuit, comprising:

a first circuit configured to receive a digital input comprising a measured angular position and filter noise of the digital input and then calculate a velocity from a time difference of a previous angular position and a filtered digital input comprising the measured angular position;

a second circuit configured to receive the velocity and filter noise from the velocity and then calculate an acceleration from a time difference of a previous velocity and the filtered velocity; and

a third circuit configured to receive the acceleration, the filtered digital input, and the filtered velocity, and filter noise of the acceleration, and then calculate a propagation delay compensated digital output using the filtered acceleration, the filtered digital input, and the filtered velocity.

7. A method of calculating propagation delay compensation, the method characterized by comprising:

receiving a digital input comprising a measured angular position of a rotating object;

comparing the measured angular position to a previously calculated angular position of the rotating object;

determining that the measured angular position is not valid based on the comparison; and

replacing the measured angular position with an extrapolated angular position based on the previously calculated angular position;

calculating a velocity from a time difference of the extrapolated angular position and a previous angular position;

calculating an acceleration using a time difference of the velocity and a previous velocity;

receiving the extrapolated angular position, the velocity, and the acceleration in a delay compensator; and

a propagation delay compensated digital output is calculated in the delay compensator.

8. The method of claim 7, further characterized by comprising:

replacing the missing measured angular position with said extrapolated angular position,

wherein the digital input comprising the measured angular position is not received;

measuring an angular position with a sensor;

sending an analog signal comprising the measured angular position to an analog-to-digital converter; and

converting the analog signal to a digital output comprising the measured angular position.

9. A method of calculating propagation delay compensation, the method characterized by comprising:

receiving a digital input comprising a measured angular position of a rotating object;

reducing noise of the digital input including the measured angular position;

calculating a velocity from a time difference of the filtered measured angular position and a previous angular position;

reducing noise from the speed;

calculating an acceleration using a time difference of the filtered velocity and a previous velocity;

reducing noise of the acceleration;

receiving the filtered measured angular position, the filtered velocity, and the filtered acceleration in a delay compensator; and

a propagation delay compensated digital output is calculated in the delay compensator.

10. The method of claim 9, further characterized by comprising:

comparing the measured angular position with a previous angular position of the rotating object;

determining that the measured angular position is not valid based on the comparison;

replacing the measured angular position with an extrapolated angular position based on the previous angular position;

collecting angular positions with a sensor;

sending an analog signal comprising the measured angular position to an analog-to-digital converter; and

converting the analog signal to a digital output comprising the measured angular position.

Background

Digital encoders are used to control manufacturing robots. Typically, one component of a digital encoder is a position sensor designed to determine the position of a mobile device. For a rotating object, the position sensor measures the angle of the rotating device relative to the starting position. The position sensor provides an analog signal to the signal processing components of the digital encoder. The signal processing section receives the analog signal and outputs a digital signal of the angular position with respect to time. The signal processing components may include an analog signal processor, an analog-to-digital converter, and a digital signal processor. The propagation time for the processed signal may delay the output of the digital signal from the encoder and provide an inaccurate angular position compared to the real-time angular position of the rotating object.

One solution to compensate for this propagation time delay is to use a system with two position sensors, each measuring the angle of a rotating object. The pair of signals from the sensor are input into two filter circuits in parallel, which provide a feedback loop for compensating for time delays. This solution is known to be susceptible to instability. Furthermore, this solution is limited by a feedback loop for compensating time delays in a small dynamic range.

New solutions are needed to provide a rotating object with an accurate angular position with respect to time.

Disclosure of Invention

The invention relates to a propagation delay compensation circuit and a method of calculating propagation delay compensation.

The technical problem solved by the present invention is that conventional solutions for compensating propagation time delays provide an inaccurate angular position compared to the real-time angular position of the rotating object.

Various embodiments of the present invention provide filters for propagation delay compensation and interpolation in encoder digital signal processing that provide angle, velocity, and acceleration.

According to a first aspect, a propagation delay compensation circuit comprises: a first low pass filter configured to receive a digital input and reduce noise of the digital input including a measured angular position; a first differentiator configured to receive a filtered digital input comprising a measured angular position and to calculate a velocity from a time difference of the measured angular position and a previous angular position; a second low pass filter configured to reduce noise from velocity; a second differentiator configured to receive the filtered velocity and calculate an acceleration using a time difference of the filtered velocity and a previous velocity; a third low-pass filter configured to reduce noise of acceleration; and a delay compensator configured to receive the filtered digital input, the filtered velocity, and the filtered acceleration, and to calculate a propagation delay compensated digital output.

In one embodiment, the propagation delay compensation further comprises an extrapolation generator configured to receive the filtered acceleration and calculate an extrapolated angular position.

In one embodiment, the propagation delay compensation circuit further comprises a pre-processing block configured to: receiving a digital input comprising a measured angular position; determining that the measured angular position is within an acceptable range and then sending a digital input comprising the measured angular position to a first low-band-pass filter; and determining that the measured angular position is not within the acceptable range and then sending a digital input including the extrapolated angular position to the first low-band-pass filter.

In one embodiment, the propagation delay compensation circuit further comprises a pre-processing block configured to: receiving a digital input comprising a measured angular position; determining that a digital input including a measured angular position is received and then sending the digital input including the measured angular position to a first low-band-pass filter; and determining that a digital input comprising the measured angular position is not received and then sending the digital input comprising the extrapolated angular position to the first low-band-pass filter.

In one embodiment, the propagation delay compensation circuit further comprises a pre-processing block configured to: receiving a digital input comprising a measured angular position; comparing the measured angular position to the extrapolated angular position for a best fit; and sending the digital input including the best-fit angular position to the first low-band-pass filter.

According to a second aspect, a propagation delay compensation circuit includes: a first circuit configured to receive a digital input comprising a measured angular position and filter noise of the digital input and then calculate a velocity from a time difference of a previous angular position and the filtered digital input comprising the measured angular position; a second circuit configured to receive the velocity and filter noise from the velocity and then calculate an acceleration from a time difference of a previous velocity and the filtered velocity; and a third circuit configured to receive the acceleration, the filtered digital input, and the filtered velocity, and filter noise of the acceleration, and then calculate a propagation delay compensated digital output using the filtered acceleration, the filtered digital input, and the filtered velocity.

According to a third aspect, a method of calculating propagation delay compensation comprises: receiving a digital input comprising a measured angular position of a rotating object; comparing the measured angular position with a previously calculated angular position of the rotating object; determining that the measured angular position is not valid based on the comparison; and replacing the measured angular position with the extrapolated angular position based on the previously calculated angular position; calculating a velocity from a time difference of the extrapolated angular position and a previous angular position; calculating acceleration using a time difference of the velocity and a previous velocity; receiving the extrapolated angular position, velocity, and acceleration in a delay compensator; and calculating a propagation delay compensated digital output in the delay compensator.

In one embodiment, the method further comprises: replacing the missing measured angular position with an extrapolated angular position, wherein no digital input comprising the measured angular position is received; measuring an angular position with a sensor; sending an analog signal comprising the measured angular position to an analog-to-digital converter; and converting the analog signal to a digital output comprising the measured angular position.

According to a fourth aspect, a method of calculating propagation delay compensation comprises: receiving a digital input comprising a measured angular position of a rotating object; reducing noise of a digital input comprising a measured angular position; calculating a velocity from a time difference of the filtered measured angular position and a previous angular position; reducing noise from speed; calculating an acceleration using a time difference of the filtered velocity and a previous velocity; reducing noise of acceleration; receiving, in a delay compensator, a filtered measured angular position, a filtered velocity, and a filtered acceleration; and calculating a propagation delay compensated digital output in the delay compensator.

In one embodiment, the method further comprises: comparing the measured angular position with a previous angular position of the rotating object; determining that the measured angular position is not valid based on the comparison; replacing the measured angular position with the extrapolated angular position based on the previous angular position; collecting angular positions with a sensor; sending an analog signal comprising the measured angular position to an analog-to-digital converter; and converting the analog signal to a digital output comprising the measured angular position.

The invention achieves the technical effect of providing an accurate angular position relative to time for a rotating object.

Drawings

The present disclosure will become more fully understood from the description and the accompanying drawings, wherein:

FIG. 1 is a graph showing the measured output of the prior art;

fig. 2 is a graph illustrating a measurement output corrected by a propagation delay compensation filter according to various embodiments;

FIG. 3 is a block diagram illustrating a measurement system according to various embodiments;

fig. 4 is a flow diagram illustrating an exemplary process for calculating delay compensation, in accordance with various embodiments;

fig. 5 is a block diagram illustrating an exemplary propagation delay compensation and interpolation circuit, in accordance with various embodiments;

fig. 6 is a graph illustrating exemplary propagation delay compensated angular measurements according to various embodiments; and is

Fig. 7 is a composite graph illustrating data calculated from exemplary measurements of a rotating object under various conditions, according to various embodiments.

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of any exemplary embodiments disclosed herein or any equivalents thereof. It should be understood that the figures are not drawn to scale. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements.

Detailed Description

The following disclosure is merely exemplary in nature and is in no way intended to limit the described embodiments, their applications, or uses. The invention has been described with reference to various exemplary embodiments. Various modifications and alterations may be made to the illustrative embodiments without departing from the scope of the invention, and all such modifications are intended to be included within the scope of the invention.

For a rotating device, a position sensor such as, for example, an angular sensor interface is directed at the device and measures the angular position of the rotating device relative to a starting position. Typically, the output angle of the sensor interface will exhibit an angle error due to propagation delays in the analog signal processing and delays in the digital signal processing after analog-to-digital conversion in the encoder. If the sensor interface is noisy, additional digital low-pass filtering or averaging is advantageous, however, such processing increases propagation delay. Furthermore, an increase in the rotational speed of the object increases the magnitude of the error in the angle measured by the sensor interface.

The problem is simplified using a constant angular velocity, the propagation delay being shown in fig. 1. Graph 100 has an x-axis 105 of time and a y-axis 106 of angular position of the rotating object. The curve 110 shows the output of a series of calculated data points 111, 112, 113, 114, 115, 116, 117 of the angular position of the rotating object at a certain time. To complicate matters, it has been determined that data point 115 is invalid. However, the curve 120 shows the actual positions and times of a series of data points 121, 122, 123, 124, 125, 126, 127.

The output of the shift to the right of the actual data point in curve 120 to the calculated data point in curve 110 is due to the propagation delay caused by: processing the analog signal from the sensor, converting the analog signal to a digital signal, processing the digital signal, and outputting a digital signal of the angular position. Due to the problem of propagation delay, the output to the position of the rotating object in curve 110 does not accurately represent the actual position of the rotating object in curve 120, as shown in FIG. 1. Although the propagation delay may be only a few milliseconds, inaccurate positions of the output can limit the ability of the robot to fabricate the micro-components.

Various embodiments described herein provide filters for propagation delay compensation and interpolation in encoder digital signal processing that provide angles, velocities, and accelerations. The propagation delay compensation and interpolation filter can provide an accurate output of the angular position in real time. The propagation delay compensation and interpolation filter may be configured to interpolate and compare the new data point to determine if the new data point is valid. In addition, the propagation delay compensation and interpolation filter may be configured for upsampling, which replaces invalid data points with extrapolated data points computed by the filter.

The input into the propagation delay compensation and interpolation filter is the processed digital signal from the encoder and the output from the propagation delay compensation and interpolation filter is the actual angular position measured by the position sensor.

Propagation delay compensation and interpolation filters have applications for position sensors, angle sensor interfaces and digital encoders. In addition, various embodiments provide methods and systems to reduce this error by extracting velocity and acceleration and compensating for delays in analog and digital blocks.

In some configurations, the propagation delay compensation and interpolation filter is a post-processing digital filter. For example, the input to the filter is the pre-processing digital angle, which may be noisy and have a delay from the pre-processing propagation. The filter may remove noise, however, this increases delay. The filter includes a series of low pass filters and differentiators for calculating angular velocity and acceleration with low noise. Assuming constant or slow changes in acceleration, the filter can compensate for all delays in the sensor signal preprocessing and the delays added by the filter. For example, the delays from analog and digital processing are known by design and may be proportional to the on-chip RC time constant. As shown mathematically herein, two coefficients are sufficient to calculate the actual angle without propagation delay by adding a correction proportional to the measured velocity and the measured acceleration. Once the acceleration is determined, the filter may extrapolate future velocities and angles. Since the output angles may be sampled at a faster rate than the input angles, extrapolation of the future speed and angle may be used for interpolation. For example, extrapolation may also be used for signal integrity verification. In the event that the input angle is not calculated or not valid, the extrapolated value may be used in place of such input angle.

An example of the propagation delay error problem is corrected by an embodiment of a propagation delay compensation and interpolation filter, as shown in fig. 2. Graph 200 has an x-axis 205 of time and a y-axis 206 of angular position of the rotating object. The curve 210 shows the output of the calculated velocity defined by a series of calculated data points 211, 212, 213, 214, 215 of the angular position of the rotating object at a certain time. The propagation delay 230 has shifted the calculated velocity to the right to the actual velocity as shown by curve 220. The output of curve 210 is the input to the propagation delay compensation and interpolation filter, which outputs the correction speed of curve 220. The filter determines the velocity and acceleration 233, which are used to correct 235 the calculation data point 211 and output a correction data point 221, as described herein. In addition, the filter may correct 236 the calculate data point 212 and output the correct data point 222, correct 237 the calculate data point 214 and output the correct data point 224, and correct 238 the calculate data point 215 and output the correct data point 225.

However, the data point 213 has been determined to be invalid. The filter determines the velocity and acceleration 240 and extrapolates the values for the data point 213, and then corrects 242 the extrapolated data point 213 and outputs a corrected data point 223. In some embodiments, curve 220 is a corrected speed, which is the actual speed of the rotating object.

If the velocity is known or measured and the propagation delay is known, the processed digital signal from the encoder may be corrected for delay and/or missing data points by propagation delay compensation and interpolation filters. Thus, the output of the propagation delay compensation and interpolation filter in curve 220 accurately represents the position and velocity of the rotating object as measured by the encoder.

Turning now to fig. 3, a block diagram illustrates an exemplary measurement system 300. For example, the measurement system 300 may be a digital encoder for controlling a manufacturing robot. The measurement system 300 may be in communication with or incorporated into any control processor that requires input of angular positions that are accurate in both time and space. The measurement system 300 is particularly advantageous for high sampling rates necessary when measuring objects rotating at high speeds (e.g., in excess of 6000 rpm). In one application, the measurement system 300 is incorporated into an electric motor.

The measurement system 300 is designed to measure the angular position of the rotating object 301 and calculate the angular position represented as the propagation delay compensated digital output 320. The sensor 303 is positioned to measure the angular position of the rotating object 301.

Examples of sensors 303 configured to measure the angular position of a rotating object 301 are well known in the art. The sensor 303 may be a transducer. For example, a transducer may be configured to convert a physical quantity, such as position, into another physical quantity, such as an electrical signal. The sensor 303 may be an optical detector. The sensor 303 may be a magnetic detector. The sensor 303 may be an inductive detector. The sensor 303 may be a capacitive detector. The sensor 303 may be a hall effect detector. If temperature is the variable in the measurement, the sensor 303 may be an infrared detector.

The sensor 303 may communicate with an angle sensor interface that processes analog electrical signals and converts the analog electrical signals to digital signals. The angle sensor interface may include an analog signal processor 305, a digital converter 307, and a digital signal processor 309 that outputs a processed digital input 312. In some configurations, the angle sensor interface may include a propagation delay compensation filter 315. The signal time propagation delay is generated by electrical analog signal processing through the angle sensor interface and conversion of the electrical analog signal to a digital signal.

The sensor 303 converts the angular position into an analog signal of electrical magnitude, which may be, for example, voltage, current, impedance, or frequency. The angular position measured by the sensor 303 may be sent as an analog signal to the analog signal processor 305. The noise of the analog signal may be reduced by the analog signal processor 305. The analog signal processor 305 processes the analog signal, which conditions the analog signal for digital conversion. The processes used by the analog signal processor 305 may include one or more of amplification, filtering, and multiplexing.

The conditioned analog signal is sent to an analog-to-digital converter 307, and the resulting digital signal may be sent to a digital signal processor 309, which processes the digital signal and outputs a processed digital input 312.

The angular position as represented by the processed digital input 312 is sent to the propagation delay compensation filter 315, which computes a propagation delay compensated digital output 320. The propagation delay compensation filter 315 may be configured to output delay compensated angular position angles, velocities, and accelerations.

An example of the operation of calculating the propagation delay compensated digital output 320 is shown in fig. 4, described below.

In some embodiments, the measurement system 300 may include: a sensor 303 configured to measure an angular position of the rotating object 301; an analog-to-digital converter 307 configured to receive the angular position and convert the angular position to a digital input 312 comprising a measured angular position; and a propagation delay compensation circuit 315 configured to receive the digital input 312 and calculate a propagation delay compensated digital output 320.

The propagation delay compensation circuit 315 may be any configuration of filters used for propagation delay compensation and interpolation in encoder digital signal processing, as described herein. The resulting propagation delay compensated digital output 320 may be represented as a propagation delay compensated measured angular position.

For example, the propagation delay compensation circuit 315 may include: a first low pass filter configured to receive a digital input 312 comprising a measured angular position and to reduce noise of the measured angular position; a first differentiator configured to receive the filtered measured angular position and calculate a velocity from a time difference of the filtered measured angular position and a previous angular position; a second low pass filter configured to reduce noise from velocity; a second differentiator configured to receive the filtered velocity and calculate an acceleration using a time difference of the filtered velocity and a previous velocity; a third low-pass filter configured to reduce noise of acceleration; and a delay compensator configured to receive the filtered digital input, the filtered velocity, and the filtered acceleration, and to calculate a propagation delay compensated digital output 320.

Another example of the propagation delay compensation circuit 315 is shown in fig. 5, described below.

In some configurations, the measurement system 300 may further include an analog signal processor 305 configured to: receive angular position from sensor 303; processing an electrical signal comprising angular position; and sends the processed angular position to analog-to-digital converter 315. For example, processing the electrical signal may be at least one of filtering the electrical signal, reducing noise of the electrical signal, amplifying the electrical signal, and multiplexing the electrical signal.

In some configurations, the measurement system 300 may further include a digital signal processor 309 configured to: receiving a digital input comprising a measured angular position; processing a digital signal comprising a measured angular position; and sends the processed digital input including the measured angular position to the propagation delay compensation circuit 315.

Turning to fig. 4, a flow chart illustrates an exemplary process for calculating delay compensation. The process 400 begins with the input of a digital signal 401. For example, the digital signal 401 may be the digital input 312 described above. The digital signal 401 includes the angular position of the rotating object at a certain time. Decision 402: is new input available? If so 404, go to decision 406. If no 405, go to step 412. The digital signal 401 may not be available because it has not been calculated or is delayed due to known problems in previous stages of signal processing. Decision 406: is the new input reasonable? If 408, go to step 410, which selects digital signal 401 to process. If not 407, then go to step 412, which selects an extrapolated value for the process. Since the propagation delay compensation knows the velocity and acceleration of the rotating object, it can be verified that the digital signal 401 is close enough to the expectation, e.g., the digital signal 401 cannot be extrapolated by 180 degrees. If an extrapolated value is selected, the digital signal 401 is discarded.

The selected signal enters a first low pass filter 414 that reduces noise. The signal then enters a first differentiator 416 which determines the velocity by calculating the time difference between successive angular positions. Calculate the velocity into a second low pass filter 418 that reduces noise; the calculated velocity then enters a second differentiator 420 which determines the acceleration by calculating the time difference between successive velocities. Calculating acceleration into a third low pass filter 422 to reduce noise; the calculated acceleration then enters delay compensation 424. Based on the measured angle, velocity, and acceleration, the digital output 430 may be compensated for a plurality of delays between the transducer measuring the angle of the rotating object and the delay compensator 424. Examples of the plurality of delays may include delays in the transducer, delays due to analog signal processing, delays for analog-to-digital conversion, delays due to digital signal processing, delays due to communication to an external device, and delays of process 400. The digital output 430 is the compensated filtered angle measurement. The extrapolation 426 calculates the delay that can be used to compensate the process 400 performed in the propagation delay compensation filter.

In some embodiments, the method 400 of calculating propagation delay compensation may include: receiving a digital input 401 comprising a measured angular position of a rotating object; reducing noise of a digital input comprising a measured angular position; calculating a velocity from a time difference of the filtered measured angular position and a previous angular position; reducing noise from speed; calculating an acceleration using a time difference of the filtered velocity and a previous velocity; reducing noise of acceleration; receiving, in a delay compensator, a filtered measured angular position, a filtered velocity, and a filtered acceleration; and a propagation delay compensated digital output 430 is calculated in the delay compensator 424.

Fig. 5 is a block diagram illustrating exemplary components in a propagation delay compensation and interpolation filter 500. The digital input 502 is a digital representation of angles that have some propagation delay due to analog and digital processing. The digital input 502 enters the filter 500 and is evaluated 503 to determine if the digital input 502 is present and within a range of acceptability. If the digital input 502 meets the criteria, it is the selected input 504 for processing. If the digital input 502 does not meet the criteria, it is rejected and the extrapolated value 520 becomes the selected input 504. The selected input 504 enters a first low pass filter 505, which reduces noise and generates a low pass filtered angle signal 515. The filtered signal is directed to a first differentiator 506 to determine a calculated velocity 507. A second low pass filter 509 receives the calculated velocity 507, which reduces noise and produces a low pass filtered velocity signal 516. The filtered signal is directed to a second differentiator 510 to determine a calculated acceleration 511. The third low pass filter 512 receives the calculated acceleration 511, which reduces noise and generates a low pass filtered acceleration signal 517.

The filtered angle signal 515, the filtered velocity signal 516, and the filtered acceleration signal 517 are directed to a delay compensation circuit 518, which calculates the propagation delay. Delay compensation circuit 518 includes a first coefficient value 526 ("k₁") and second coefficient values 525 (" k₂") which are further defined in the equations below.

In this example of filter 500, only a first order low pass filter for angle, velocity and acceleration has been used, however, higher order low pass filters may be used.

In the event that the input signal 502 is determined to be invalid or upsampled, the filter input may be switched between the digital input 502 and the extrapolated value 520. Once the new digital input 502 to the filter 500 is available from the pre-processing block, it may be compared to the extrapolated angle 520 output by the filter. If there is a large discrepancy, the new digital input 502 may be discarded and replaced with an extrapolation angle 520. Filter 500 may reject new digital input 520 as a contour line or input with very noisy input. If for some reason, the new digital input 502 is not available (e.g., the analog block is running the auto-zero feature), then the extrapolated value 520 is used instead of keeping the previous input.

The signals fed back to the input for interpolation or upsampling use different compensation coefficients (k)₁ ⁱAnd k₂ ⁱ) Because the digital input 502 is affected by the delay in the previous stage, the extrapolated value 520 is not affected by the delay.

The signal fed back to the input for interpolation or upsampling uses a first extrapolation coefficient 528 ("k₁ ⁱ") and a second extrapolation coefficient 527 (" k₂ ⁱ"). In one example, the first extrapolation coefficient 528 ("k₁ ⁱ") may be the first coefficient value 526 (" k ") from the previous numerical input₁") and a second extrapolation coefficient 527 (" k ")₂ ⁱ") may be a second coefficient value 525 (" k ") from a previous numerical input₂”)。

In some implementations, the propagation delay compensation circuit 500 may include: a first low pass filter 505 configured to receive the digital input 502 and reduce noise of the digital input 502 including the measured angular position; a first differentiator 506 configured to receive the filtered digital input 515 comprising the measured angular position and to calculate a speed 507 from a time difference of the measured angular position and a previous angular position; a second low pass filter 509 configured to reduce noise from the velocity 507; a second differentiator 510 configured to receive the filtered velocity 516 and calculate an acceleration 511 using a time difference of the filtered velocity 516 and a previous velocity; a third low-pass filter 512 configured to reduce noise of the acceleration 511; and a delay compensator 518 configured to receive the filtered digital input 515, the filtered velocity 516, and the filtered acceleration 517, and to calculate a propagation delay compensated digital output 530.

The propagation delay compensation circuit 500 may include an extrapolation generator 519 configured to receive the filtered acceleration 517 and calculate an extrapolated angular position 520.

The propagation delay compensation circuit may include a preprocessing block 503 configured to: receiving a digital input 502 comprising a measured angular position; determining that the measured angular position is within an acceptable range and then sending the digital input 502 including the measured angular position to a first low band pass filter 505; and determining that the measured angular position is not within the acceptable range and then sending the digital input including the extrapolated angular position 520 to the first low-band-pass filter 505.

The pre-processing block 503 may be configured to determine that the digital input 502 has not been received and then send the digital output 504 including the extrapolated angular position 520 to the first low-band-pass filter 505.

The propagation delay compensation circuit 505 may include a pre-processing block 503 configured to: receiving a digital input 502 comprising a measured angular position; determining that a digital input 502 comprising a measured angular position is received, then sending the digital input 502 comprising the measured angular position to a first low-band-pass filter 505; and determining that digital input including measured angular position has not been received 502 and then sending digital input including extrapolated angular position 520 504 to first low-band filter 505.

The propagation delay compensation circuit 500 may include a pre-processing block 503 configured to: receiving a digital input 502 comprising a measured angular position; comparing the measured angular position to the extrapolated angular position for a best fit; and sends the digital input 504 including the best-fit angular position to the first low-band-pass filter 505.

In some applications, the propagation delay compensated digital output 530 is a propagation delay compensated measured angular position. In some applications, the propagation delay compensated digital output 530 is a propagation delay compensated extrapolated angular position. In some applications, the propagation delay compensated digital output 530 is a filtered measured angular position.

Filter 500 may use the extrapolated features to operate at a higher sampling frequency than the pre-processing block. This is particularly beneficial if the sampling of the sensor output is asynchronous to the internal clock, as it reduces jitter. If used as an anti-aliasing filter, the filter 500 bandwidth may also be limited without introducing additional lag.

In a non-limiting example of the circuit 500 in operation, the following equation may be used to correct for propagation delay. Assuming constant acceleration and N clock delays in signal preprocessing, the position in the Z domain sampled at intervals of T is:

IN(Z)＝[Acc T² Z^-1(1+Z^-1)/(1-Z^-1)³+Speed T Z^-1/(1-Z^-1)²+Pos/(1-Z^-1)]Z^-N(equation 1)

For equation 1, Acc is acceleration, Pos is position, in (Z) is position in the Z domain, and T is time interval. In the Z domain, Z is a variable. The Z-field requires a fixed sampling time interval T. In this example, equation 1 calculates the propagation delay.

The first filter determines the location of the average low pass filter as calculated in equation 2, where H₁Is the transfer function of the noise reduction filter 505, and in (z) is from equation 1:

IN_a(Z)＝H₁(Z) IN (Z) (Eq.2)

The derivative and second filter determine the average velocity as calculated in equation 3, where H₂Is the transfer function of the noise reduction filter 509, and IN_a(Z) is from equation 2:

S_a(Z)＝(1-Z^-1)H₂(Z)IN_a(Z) (Eq 3)

Equation 3 may be rearranged and represented as equation 4:

S_a(Z)＝(1-Z^-1)H₂(Z)H₁(Z) IN (Z) (Eq. 4)

The derivative and third filter determine the average acceleration as calculated by equation 5, where H₃Is the transfer function of noise reduction filter 5012, and S_a(Z) is from equation 3:

A_a(Z)＝(1-Z^-1)H₃(Z)S_a(Z) (Eq.5)

Equation 5 can be rearranged and represented as equation 6:

A_a(Z)＝(1-Z^-1)²H₃(Z)H₂(Z)H₁(Z) IN (Z) (Eq.6)

The third filter output is the acceleration, which is assumed to be constant. In various applications, the acceleration may change, and the third filter may take some time to stabilize. Once the third filter is stabilized, the propagation delay can be compensated without any residual error.

The compensation speed is calculated by equation 7, where S_a(Z) is from equation 3, A_a(Z) is from equation 5, and k₂Is the coefficient:

S_c(Z)＝S_a(Z)+k₂ A_a(Z) (equation 7)

Equation 7 may be rearranged and represented as equation 8:

S_c(Z)＝[(1-Z^-1)+k₂(1-Z^-1)²H₃(Z)]H₂(Z)H₁(Z) IN (Z) (Eq.8)

The compensated position is calculated by equation 9, where IN_a(Z) is from equation 2, S_c(Z) is from equation 7, and k₁Is the coefficient:

OUT(Z)＝IN_a(Z)+k₁ S_c(Z) (equation 9)

Equation 9 may be rearranged and represented as equation 10:

OUT(Z)＝H₁(Z)IN(Z)+k₁((1-Z^-1)H₂(Z)H₁(Z)IN(Z)+k₂(1-Z^-1)²H₃(Z)H₂(Z)H₁(Z) IN (Z) (Eq. 10)

Equation 9 may be rearranged and represented as equation 11:

OUT(Z)＝[1+k₁(1-Z^-1)H₂(Z)+k₁k₂(1-Z^-1)²H₃(Z)H₂(Z)]H₁(Z) IN (Z) (Eq. 11)

The error between the filter output and the actual position (N clocks before the filter input) is:

E(Z)＝OUT(Z)-IN(Z)Z^N(equation 12)

Coefficient k₁And coefficient k₂Can be inserted into equation 12 and expressed as equation 13:

E(Z)＝[H₁(Z)+k₁(1-Z^-1)H₂(Z)H₁(Z)+k₁k₂(1-Z^-1)²H₃(Z)H₂(Z)H₁(Z)-Z^N]IN (Z) (equation 13)

Equation 13 calculates the error dynamics for any rotor motion. Next, assuming that the rotor is constantly accelerating, a coefficient k is determined when the error converges to 0₁And coefficient k₂. The error will settle to zero when the following occurs:

Lim_Z->1(1-Z^-1) E (z) ═ 0 (equation 14)

Therefore, 3 conditions are required to solve for k₁Coefficient sum k₂Coefficient:

condition 1: acceleration is 0, velocity is 0, and position is not equal to 0

Lim_Z->1(1-Z^-1) E (z) ═ 0, meaning H₁(1) 1 means that the first filter must have a DC gain of 1.

Condition 2: acceleration 0, speed 0, position 0

Lim_Z->1(1-Z^-1) E (z) ═ 0, meaning k₁＝(N-d{H₁(1)})/H₂(1)

Condition 3: acceleration ≠ 0, speed ≠ 0, position ≠ 0

Lim_Z->1(1-Z^-1) E (z) ═ 0, means

k₂＝[N²+N-d²{H₁(1)}-2d{H₁(1)}-2k₁ d{H₂(1)H₁(1)}]/[2H₃(1)(N-d{H₁(1)})]Wherein: d { H }₁(1) Is H₁(Z) the derivative when Z ═ 1;

coefficient (k)₁And k₂) The above equation can be used to solve. The signals fed back to the input for interpolation or upsampling use different compensation coefficients (k)₁ ⁱAnd k₂ ⁱ) The compensation coefficient may be a coefficient (k) from a previous digital input₁And k₂). For interpolation, there is no propagation delay N, because the signal does not include signal processing delays and digital conversion delays from the corner sensor interfaceIt is late.

In the Z domain, the filter is represented as a multiplication factor containing the variable Z. For example, the digital register 505 is updated every T seconds. If the output of 505 is an input delayed by T seconds, then the digital delay is labeled Z in the Z domain^-1. In this example, output register (Z) ═ Z^-1INregister(Z)。

To calculate the difference between the input at time T and the previous input at time T-T, the equation is: out (Z) ═ in (Z) — Z^-1IN (Z) or OUT (Z) -1-Z^-1) IN (Z). Factor (1-Z), which may be referred to as a transfer function^-1) Is a filter that performs temporal differences. More complex transfer functions or filters can be designed and are generally denoted as H_n(Z)。

In the time domain, t is a variable representing time in seconds. In the time domain, the input 500 is in (t). In the time domain, the equations change rapidly, become very complex and impossible to decipher.

In some applications, the coefficient (k)₁And k₂) May be determined using top level simulation. In some applications, the coefficient (k)₁And k₂) Can be determined by building a test model and performing bench measurements to solve for the coefficients.

Turning now to fig. 6, a graph 600 illustrates an example of comparing an input 610 into a propagation delay compensation and interpolation filter with a resulting output 620. Graph 600 has an x-axis 605 of time in milliseconds (not shown in fig. 6) and a y-axis 606 of position in millivolts. The output 620 may be represented as a line, which is an angle 630. A delay compensation for communication delay between the sensor and the host system may also be calculated.

In this example, the pre-processed signal input 610 is delayed by 6.75 μ s due to the analog and digital front ends. The front end sampling period is 2 mus. The output 620 is delay compensated and upsampled by a factor of 4. With the correct coefficients, each data point of the output 620 is precisely aligned with the rotor position of the rotating object. For example, data point 615 of input 610 has a propagation delay 627 and is corrected to data point 625 of output 620. In this example, the input data points 615 are 9.6355ms, 779.53 mV; calibration data points 625 were 9.62875ms, 779.53 mV; and the propagation delay 627 is 6.75 mus. The speed was 311.001 mV/s.

Finally, FIG. 7 shows a composite graph 700 showing data from an exemplary simulation overlaid on the same time scale. In graph 701, sensor output 710, which is the output of the propagation delay compensation and interpolation filter, accurately covers angle 715, which is the actual rotor position. In graph 702, sensor speed 720 (which is the calculated speed from the propagation delay compensation and interpolation filter) covers speed 725 (which is the actual speed of the rotor). In graph 702, the acceleration may be constant, which results in a precise velocity and a precise position. In graph 703, the increase and decrease of sensor acceleration 730 (which is the calculated acceleration from the propagation delay compensation and interpolation filter) is slightly delayed according to acceleration 735 (which is the actual acceleration of the rotor). In graph 704, post-error 740 (which is the sensor error after the filter post-processing) shows the post-error processing that is primarily related to a slight delay in calculating the acceleration compared to the actual acceleration. The calculated post-processing error is 35uV/1V < + > -12.6mdeg/360 deg. In graph 705, pre-error 750 (which is the sensor error before delay compensation) shows a significant error of the angle measurement that can be eliminated by using propagation delay compensation and interpolation filters. The calculated sensor error before delay compensation is +/-750uV/1V +/-270mdeg/360 deg.

In some implementations, the propagation delay compensation circuit can include: a first low pass filter configured to receive a digital input and reduce noise of the digital input including a measured angular position; a first differentiator configured to receive a filtered digital input comprising a measured angular position and to calculate a velocity from a time difference of the measured angular position and a previous angular position; a second low pass filter configured to reduce noise from velocity; a second differentiator configured to receive the filtered velocity and calculate an acceleration using a time difference of the filtered velocity and a previous velocity; a third low-pass filter configured to reduce noise of acceleration; and a delay compensator configured to receive the filtered digital input, the filtered velocity, and the filtered acceleration, and to calculate a propagation delay compensated digital output.

The propagation delay compensation circuit may include an extrapolation generator configured to receive the filtered acceleration and calculate an extrapolated angular position.

The propagation delay compensation circuit may include a preprocessing block configured to: receiving a digital input comprising a measured angular position; determining that the measured angular position is within an acceptable range and then sending a digital input comprising the measured angular position to a first low-band-pass filter; and determining that the measured angular position is not within the acceptable range and then sending a digital input including the extrapolated angular position to the first low-band-pass filter.

The pre-processing block may be configured to determine that a digital input was not received and then send a digital output including an extrapolated angular position to the first low-band-pass filter.

The propagation delay compensation circuit may include a preprocessing block configured to: receiving a digital input comprising a measured angular position; determining that a digital input including a measured angular position is received and then sending the digital input including the measured angular position to a first low-band-pass filter; and determining that a digital input comprising the measured angular position is not received and then sending the digital input comprising the extrapolated angular position to the first low-band-pass filter.

The propagation delay compensation circuit may include a preprocessing block configured to: receiving a digital input comprising a measured angular position; comparing the measured angular position to the extrapolated angular position for a best fit; and sending the digital input including the best-fit angular position to the first low-band-pass filter.

In some applications, the propagation delay compensated digital output is a propagation delay compensated measured angular position. In some applications, the propagation delay compensated digital output is a propagation delay compensated extrapolated angular position. In some applications, the propagation delay compensated digital output is a filtered measured angular position.

In some embodiments, a system may comprise: a sensor configured to measure an angular position of a rotating object; an analog-to-digital converter configured to receive the angular position and convert the angular position to a digital input comprising a measured angular position; and a propagation delay compensation circuit, the propagation delay compensation circuit comprising: a first low pass filter configured to receive a digital input comprising a measured angular position and to reduce noise of the measured angular position; a first differentiator configured to receive the filtered measured angular position and calculate a velocity from a time difference of the filtered measured angular position and a previous angular position; a second low pass filter configured to reduce noise from velocity; a second differentiator configured to receive the filtered velocity and calculate an acceleration using a time difference of the filtered velocity and a previous velocity; a third low-pass filter configured to reduce noise of acceleration; and a delay compensator configured to receive the filtered digital input, the filtered velocity, and the filtered acceleration, and to calculate a propagation delay compensated digital output.

The system may include an analog signal processor configured to: receiving an angular position from a sensor; processing an electrical signal comprising angular position; and sending the processed angular position to an analog-to-digital converter. Processing the electrical signal may include any one or any combination of the following: filtering the electrical signals, reducing noise of the electrical signals, amplifying the electrical signals, and multiplexing the electrical signals.

The system may include a digital signal processor configured to: receiving a digital input comprising a measured angular position; processing a digital signal comprising a measured angular position; and sending the processed digital input including the measured angular position to a propagation delay compensation circuit.

The sensor may be a transducer, optical detector, magnetic detector, inductive detector, capacitive detector, or hall effect detector. The propagation delay compensated digital output may be a propagation delay compensated measured angular position.

In some embodiments, a method of calculating propagation delay compensation may comprise: receiving a digital input comprising a measured angular position of a rotating object; reducing noise of a digital input comprising a measured angular position; calculating a velocity from a time difference of the filtered measured angular position and a previous angular position; reducing noise from speed; calculating an acceleration using a time difference of the filtered velocity and a previous velocity; reducing noise of acceleration; receiving, in a delay compensator, a filtered measured angular position, a filtered velocity, and a filtered acceleration; and calculating a propagation delay compensated digital output in the delay compensator.

The method can comprise the following steps: comparing the measured angular position with a previous angular position of the rotating object; determining that the measured angular position is not valid based on the comparison; and replacing the measured angular position with the extrapolated angular position based on the previous angular position.

The method can comprise the following steps: collecting angular positions with a sensor; sending an analog signal comprising the measured angular position to an analog-to-digital converter; and converting the analog signal to a digital output comprising the measured angular position.

The method may include sending the propagation delay compensated digital output to a controller. In some applications of the method, the propagation delay compensated digital output is a propagation delay compensated measured angular position.

In the foregoing specification, the invention has been described with reference to specific exemplary embodiments thereof. The particular embodiments shown and described are illustrative of the invention and its best mode and are not intended to otherwise limit the scope of the invention in any way. Indeed, for the sake of brevity, conventional manufacturing, connecting, fabrication, and other functional aspects of the methods and systems may not be described in detail. Furthermore, the connecting lines shown in the various figures are intended to represent example functional relationships and/or steps between the various elements. There may be many alternative or additional functional relationships or physical connections in a practical system.

It should be understood that the steps within a method may be performed in a different order without altering the principles of the present disclosure. For example, various embodiments may be described herein in terms of various functional components and processing steps. It should be understood that such components and steps may be realized by any number of hardware components configured to perform the specified functions.

Additionally, the components and/or elements recited in any apparatus embodiment may be assembled or otherwise operationally configured in a variety of permutations to produce substantially the same result as the present technique and are therefore not limited to the specific configuration set forth in the specific example.

As used herein, the phrase "at least one of A, B and C" may be understood to mean logic (a or B or C), however, the use of non-exclusive logic "or" may be in contrast to meaning (A, B and C), and further may be understood to mean (a and B) or (a and C) or (B and C). As used herein, the phrase "A, B and/or C" should be understood to mean (A, B and C) or alternatively (a or B or C), using the non-exclusive logical "or".

The present invention has been described above in connection with various exemplary embodiments and examples, which are not intended to limit the full scope of the systems and methods of the present invention. However, those skilled in the art will recognize that equivalent changes, modifications and variations of embodiments, materials, systems and methods may be made within the scope of the present invention, with substantially similar results, and are intended to be included within the scope of the present invention, as set forth in the following claims.

According to a first aspect, a propagation delay compensation circuit comprises: a first low pass filter configured to receive a digital input and reduce noise of the digital input including a measured angular position; a first differentiator configured to receive a filtered digital input comprising a measured angular position and to calculate a velocity from a time difference of the measured angular position and a previous angular position; a second low pass filter configured to reduce noise from velocity; a second differentiator configured to receive the filtered velocity and calculate an acceleration using a time difference of the filtered velocity and a previous velocity; a third low-pass filter configured to reduce noise of acceleration; and a delay compensator configured to receive the filtered digital input, the filtered velocity, and the filtered acceleration, and to calculate a propagation delay compensated digital output.

In one embodiment, the propagation delay compensation circuit further comprises an extrapolation generator configured to receive the filtered acceleration and calculate an extrapolated angular position.

In one embodiment, the propagation delay compensation circuit further comprises a pre-processing block configured to: receiving a digital input comprising a measured angular position; determining that the measured angular position is within an acceptable range and then sending a digital input comprising the measured angular position to a first low-band-pass filter; and determining that the measured angular position is not within the acceptable range and then sending a digital input including the extrapolated angular position to the first low-band-pass filter.

In one embodiment, the pre-processing block is configured to determine that a digital input has not been received and then send a digital output including extrapolated angular positions to the first low-band-pass filter.

In one embodiment, the propagation delay compensation circuit further comprises a pre-processing block configured to: receiving a digital input comprising a measured angular position; determining that a digital input including a measured angular position is received and then sending the digital input including the measured angular position to a first low-band-pass filter; and determining that a digital input comprising the measured angular position is not received and then sending the digital input comprising the extrapolated angular position to the first low-band-pass filter.

In one embodiment, the propagation delay compensation circuit further comprises a pre-processing block configured to: receiving a digital input comprising a measured angular position; comparing the measured angular position to the extrapolated angular position for a best fit; and sending the digital input including the best-fit angular position to the first low-band-pass filter.

In one embodiment, the propagation delay compensated digital output is a propagation delay compensated measured angular position.

In one embodiment, the propagation delay compensated digital output is a propagation delay compensated extrapolated angular position.

In one implementation, the propagation delay compensated digital output is a filtered measured angular position.

According to a second aspect, a system comprises: a sensor configured to measure an angular position of a rotating object; an analog-to-digital converter configured to receive the angular position and convert the angular position to a digital input comprising a measured angular position; and a propagation delay compensation circuit, the propagation delay compensation circuit comprising: a first low pass filter configured to receive a digital input comprising a measured angular position and to reduce noise of the measured angular position; a first differentiator configured to receive the filtered measured angular position and calculate a velocity from a time difference of the filtered measured angular position and a previous angular position; a second low pass filter configured to reduce noise from velocity; a second differentiator configured to receive the filtered velocity and calculate an acceleration using a time difference of the filtered velocity and a previous velocity; a third low-pass filter configured to reduce noise of acceleration; and a delay compensator configured to receive the filtered digital input, the filtered velocity, and the filtered acceleration, and to calculate a propagation delay compensated digital output.

In one embodiment, the system further comprises an analog signal processor configured to: receiving an angular position from a sensor; processing an electrical signal comprising angular position; and sending the processed angular position to an analog-to-digital converter.

In one embodiment, processing the electrical signal is at least one of filtering the electrical signal, reducing noise of the electrical signal, amplifying the electrical signal, and multiplexing the electrical signal.

In one embodiment, the system further comprises a digital signal processor configured to: receiving a digital input comprising a measured angular position; processing a digital signal comprising a measured angular position; and sending the processed digital input including the measured angular position to a propagation delay compensation circuit.

In one embodiment, the sensor comprises a transducer, an optical detector, a magnetic detector, an inductive detector, a capacitive detector, or a hall effect detector.

In one embodiment, the propagation delay compensated digital output is a propagation delay compensated measured angular position.

According to a third aspect, a method of calculating propagation delay compensation comprises: receiving a digital input comprising a measured angular position of a rotating object; reducing noise of a digital input comprising a measured angular position; calculating a velocity from a time difference of the filtered measured angular position and a previous angular position; reducing noise from speed; calculating an acceleration using a time difference of the filtered velocity and a previous velocity; reducing noise of acceleration; receiving, in a delay compensator, a filtered measured angular position, a filtered velocity, and a filtered acceleration; and calculating a propagation delay compensated digital output in the delay compensator.

In one embodiment, the method further comprises: comparing the measured angular position with a previous angular position of the rotating object; determining that the measured angular position is not valid based on the comparison; and replacing the measured angular position with the extrapolated angular position based on the previous angular position.

In one embodiment, the method further comprises: collecting angular positions with a sensor; sending an analog signal comprising the measured angular position to an analog-to-digital converter; and converting the analog signal to a digital output comprising the measured angular position.

In one embodiment, the method further comprises sending the propagation delay compensated digital output to a controller.

In one embodiment, the propagation delay compensated digital output is a propagation delay compensated measured angular position.

According to a fourth aspect, a propagation delay compensation circuit includes: a first circuit configured to receive a digital input comprising a measured angular position and filter noise of the digital input and then calculate a velocity from a time difference of a previous angular position and the filtered digital input comprising the measured angular position; a second circuit configured to receive the velocity and filter noise from the velocity and then calculate an acceleration from a time difference of a previous velocity and the filtered velocity; and a third circuit configured to receive the acceleration, the filtered digital input, and the filtered velocity, and filter noise of the acceleration, and then calculate a propagation delay compensated digital output using the filtered acceleration, the filtered digital input, and the filtered velocity.

In one embodiment, the propagation delay compensation circuit further comprises an extrapolation generator configured to receive the filtered acceleration and calculate an extrapolated angular position.

In one embodiment, the propagation delay compensation circuit further comprises a pre-processing block configured to: receiving a digital input comprising a measured angular position; determining that the measured angular position is within an acceptable range and then sending a digital input including the measured angular position to the first circuit; and determining that the measured angular position is not within the acceptable range and then sending a digital input including the extrapolated angular position to the first circuit.

In one embodiment, the pre-processing block is configured to determine that a digital input has not been received and then send the digital input including the extrapolated angular position to the first circuit.

In one embodiment, the propagation delay compensation circuit further comprises a pre-processing block configured to: receiving a digital input comprising a measured angular position; determining that a digital input comprising a measured angular position is received and then sending the digital input comprising the measured angular position to the first circuit; and determining that a digital input comprising the measured angular position has not been received and then sending the digital input comprising the extrapolated angular position to the first circuit.

In one embodiment, the propagation delay compensation circuit further comprises a pre-processing block configured to: receiving a digital input comprising a measured angular position; comparing the measured angular position to the extrapolated angular position for a best fit; and sending the digital input including the best-fit angular position to the first circuit.

In one embodiment, the propagation delay compensated digital output is a propagation delay compensated measured angular position.

In one embodiment, the extrapolated angular position is a propagation delay compensated extrapolated angular position.

In one implementation, the propagation delay compensated digital output is a delay compensated angular position.

According to a fifth aspect, a system comprises: a sensor configured to measure an angular position of a rotating object; an analog-to-digital converter configured to receive the angular position and convert the angular position to a digital input comprising a measured angular position; and a propagation delay compensation circuit, the propagation delay compensation circuit comprising: a first circuit configured to receive a digital input comprising a measured angular position and filter noise of the digital input and then calculate a velocity from a time difference of a previous angular position and the filtered digital input comprising the measured angular position; a second circuit configured to receive the velocity and filter noise from the velocity and then calculate an acceleration from a time difference of a previous velocity and the filtered velocity; and a third circuit configured to receive the acceleration, the filtered digital input, and the filtered velocity, and filter noise of the acceleration, and then calculate a propagation delay compensated digital output using the filtered acceleration, the filtered digital input, and the filtered velocity.

In one embodiment, the system further comprises an analog signal processor configured to: receiving an angular position from a sensor; processing an electrical signal comprising angular position; and sending the processed angular position to an analog-to-digital converter.

In one embodiment, processing the electrical signal is at least one of filtering the electrical signal, reducing noise of the electrical signal, amplifying the electrical signal, and multiplexing the electrical signal.

In one embodiment, the system further comprises a digital signal processor configured to: receiving a digital input comprising a measured angular position; processing a digital signal comprising a measured angular position; and sending the processed digital input including the measured angular position to a propagation delay compensation circuit.

In one embodiment, the sensor comprises a transducer, an optical detector, a magnetic detector, an inductive detector, a capacitive detector, or a hall effect detector.

In one implementation, the propagation delay compensated digital output is a propagation delay compensated angular position.

The invention discloses a method for calculating propagation delay compensation, which comprises the following steps: receiving a digital input comprising a measured angular position of a rotating object; comparing the measured angular position with a previously calculated angular position of the rotating object; determining that the measured angular position is not valid based on the comparison; and replacing the measured angular position with the extrapolated angular position based on the previously calculated angular position; calculating a velocity from a time difference of the extrapolated angular position and a previous angular position; calculating acceleration using a time difference of the velocity and a previous velocity; receiving the extrapolated angular position, velocity, and acceleration in a delay compensator; and calculating a propagation delay compensated digital output in the delay compensator.

In one embodiment, the method further comprises: replacing the missing measured angular position with an extrapolated angular position, wherein no digital input comprising the measured angular position is received.

In one embodiment, the method further comprises: measuring an angular position with a sensor; sending an analog signal comprising the measured angular position to an analog-to-digital converter; and converting the analog signal to a digital output comprising the measured angular position.

In one embodiment, the method further comprises sending the propagation delay compensated digital output to a controller.

In one implementation, the propagation delay compensated digital output is a propagation delay compensated angular position.