A method for zeroing the cumulative error of a sensor under arbitrary mechanical transmission ratio

Abstract

This invention provides a method for zeroing the cumulative error of a sensor under any mechanical transmission ratio, applicable to scanning turntables with any mechanical transmission ratio, and accurately measuring turntable position changes under any transmission ratio. The invention involves installing a light-shielding plate with a width of 3-4 mm on a rotating shaft. The light-shielding plate rotates with the shaft, while a photoelectric sensor is installed on a stationary frame, serving as a signal generator to zero the cumulative error. This method is low-cost, has simple hardware circuitry, and can accurately measure turntable position changes under any transmission ratio.

Description

Technical Field

[0001] This invention relates to the field of sensor cumulative error elimination technology, and specifically to a method for zeroing the cumulative error of a sensor under any mechanical transmission ratio. Background Technology

[0002] Because of the tolerances in machining, regardless of whether the design value is an integer or non-integer mechanical transmission ratio, when the turntable rotates continuously at 360° for a long time, cumulative errors will occur.

[0003] Most existing methods for eliminating accumulated errors are designed for servo systems of stepper motors or for transmission errors in industrial machine tools. They also compensate through data processing methods such as interpolation and incremental compensation. These methods cannot meet the requirements for eliminating accumulated errors caused by mechanical and electrical sampling reasons during long-term operation under any mechanical transmission ratio. Summary of the Invention

[0004] In view of this, the present invention provides a method for zeroing the cumulative error of a sensor under any mechanical transmission ratio, which can be applied to scanning turntables with any mechanical transmission ratio and accurately measure the position change of the turntable under any transmission ratio.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] The present invention discloses a method for zeroing the cumulative error of a sensor under any mechanical transmission ratio. A light-shielding plate with a width of 3-4 mm is installed on a rotating shaft. The light-shielding plate rotates with the rotating shaft. A photoelectric sensor is installed on a stationary frame as a signal generator to generate a signal for zeroing the cumulative error. For a turntable that rotates continuously for a long time at 360°, the rising or falling edge of the photoelectric sensor is used as the zeroing mark. After each rotation, the zero bias is automatically cleared to eliminate the cumulative error caused by multiple rotations.

[0007] The falling edge is used as the zeroing marker. When the falling edge of the photoelectric sensor is read, the current resolver value is subtracted from the zero bias value, and this is taken as the zero point of the resolver. The read resolver value is multiplied by K to obtain the position value of the turntable. K is the scale value, which corrects the feedback value of the position sensor of the two-dimensional turntable. The turntable is automatically zeroed at the falling edge of the photoelectric sensor every time it rotates.

[0008] The process of obtaining the K value includes the following steps: the turntable under test is installed on the position calibration turntable, the angle value output by the resolver is measured after one revolution of the turntable under test, 3 to 5 measurements are performed, the average value of the angle sampling is obtained, and the scale value K is calculated, K = 360 / resolver output angle.

[0009] Among them, a coarse and fine channel is formed by combining two rotational transformers, and the angle after combination is the final position value.

[0010] This includes the following steps:

[0011] 1) Set four variables: the previous coarse channel zero-position raw value Apstc1, the previous fine channel zero-position raw value Apstj1, the current coarse channel position value Apstc, and the current fine channel position value Apstj;

[0012] 2) During the rotation of the turntable, when it first passes the falling edge of the photoelectric sensor, the original values ​​of the coarse channel zero position and the fine channel zero position are recorded as zero, and the current coarse channel position value and the current fine channel position value are also recorded as zero, that is:

[0013] Apstc1=0.0;Apstj1=0.0;

[0014] Apstc = 0.0; Apstj = 0.0

[0015] 3) The turntable continues to rotate, and the values ​​of the coarse and fine channels are recorded in real time and assigned to Apstc and Apstj respectively. The values ​​are then combined according to the algorithm to form the current position of the turntable, Apst.

[0016] 4) Differentiate and filter the position value Apst to obtain the velocity value;

[0017] 5) A light-shielding plate and a photoelectric sensor are used as the hardware generator for the zeroing signal; the light-shielding plate enters the photoelectric sensor in two directions, which are determined by the speed value, i.e., positive and negative.

[0018] 6) The power supply for the photoelectric sensor is +5V. When the light-shielding plate enters the photoelectric sensor, it blocks the photoelectric sensor, and the output of the photoelectric sensor is high level; when the light-shielding plate is removed from the photoelectric sensor, the output of the photoelectric sensor is low level.

[0019] Beneficial effects:

[0020] 1. This invention involves mounting a light-shielding plate with a width of 3-4 mm on a rotating shaft. The light-shielding plate rotates with the rotating shaft, while a photoelectric sensor is mounted on a stationary frame, serving as a signal generator to clear the accumulated error. It is low-cost, has a simple hardware circuit, and can accurately measure changes in the turntable position under any transmission ratio.

[0021] 2. In this invention, the test turntable is installed on a high-precision position calibration turntable. The angle value output by the resolver is measured after one revolution of the test turntable. Three to five measurements are performed to obtain the average value of the angle samples. The scale K value is calculated, and this value is used to correct the feedback value of the position sensor of the two-dimensional position turntable, thereby improving the sampling accuracy of the sensor.

[0022] 3. In this invention, the falling edge is used as the zeroing marker. Upon reading the falling edge of the photoelectric sensor, the current resolver value is subtracted from the zero bias value, and this value is used as the zero point of the resolver. The read resolver value is multiplied by K to obtain the turntable's position value. The turntable automatically zeroes at the falling edge of the photoelectric sensor every time it rotates one revolution, eliminating the accumulated error caused by multiple rotations. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the implementation of an embodiment of the present invention. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] This invention provides a method for clearing the cumulative error of a sensor under arbitrary mechanical transmission ratios, applicable to two-dimensional servo turntables with arbitrary mechanical transmission ratios. This embodiment is used in a scanning turntable of an xxx toxic agent alarm device. This scanning turntable uses a mechanical transmission method, specifically, the transmission ratio between the position sensor (rotary transformer) and the main shaft is 100:3, meaning that for every 3 rotations of the turntable, the rotary transformer rotates 100 times. Due to tolerances in machining, regardless of whether the design value is an integer or non-integer transmission ratio, cumulative errors will occur when the turntable rotates continuously for a long period of time (360°). This invention addresses this by installing a light-shielding plate with a width of 3-4mm on the rotating shaft. The light-shielding plate rotates with the rotating shaft, and a photoelectric sensor is installed on a stationary frame, serving as a signal generator to clear the cumulative error. For turntables rotating continuously for a long period of time (360°), to eliminate cumulative errors, the falling edge of the photoelectric sensor is used as the clearing indicator. Zero offset clearing is automatically performed after each rotation, eliminating the cumulative error caused by multiple rotations. The specific steps are as follows:

[0026] A light-shielding plate with a width of 3-4 mm is installed on the rotating shaft. The light-shielding plate rotates with the rotating shaft. A photoelectric sensor is installed on the stationary frame as a signal generator to generate a zero-accumulation error.

[0027] Install the turntable under test onto a high-precision position calibration turntable, measure the angle value output by the resolver after one revolution of the turntable under test, perform 3 to 5 measurements, calculate the average value of the angle samples, and calculate the scale K value, K = 360 / resolver output angle. This value corrects the feedback value of the position sensor of the position 2D turntable, improving the sensor sampling accuracy.

[0028] The photoelectric sensor is powered by +5V. When the light-shielding plate enters the photoelectric sensor, it blocks the sensor, and the sensor outputs a high level. When the light-shielding plate moves out of the sensor, the sensor outputs a low level. If the light-shielding plate is too narrow, the blocking will be incomplete, and the output level of the photoelectric sensor will be ambiguous. Therefore, the light-shielding plate should be approximately 3mm wide. This width will introduce randomness into the zeroing process of the turntable within the high-level range.

[0029] To eliminate the randomness of zeroing, the rising or falling edge of the voltage level change is used as the zeroing flag. In this embodiment, the falling edge is used as the zeroing flag. When the falling edge of the photoelectric sensor is read, the current resolver value is subtracted from the zero bias value, and this is taken as the zero point of the resolver. The read resolver value is multiplied by K to obtain the position value of the turntable. Every time the turntable rotates, it automatically zeros at the falling edge of the photoelectric sensor to eliminate the cumulative error caused by multiple rotations.

[0030] Specifically, this embodiment uses a combination of two rotary transformers to form coarse and fine channels, and the combined angle is the final position value. The flowchart is as follows. Figure 1 As shown, it includes the following steps:

[0031] 6) Set four variables: the previous coarse channel zero-position original value Apstc1, the previous fine channel zero-position original value Apstj1, the current coarse channel position value Apstc, and the current fine channel position value Apstj.

[0032] 7) The angle is inaccurate if the turntable does not pass the zero-position photoelectric sensor during rotation. Upon first passing the falling edge of the photoelectric sensor, the original zero-position values ​​of the coarse and fine channels are recorded as zero, and the current coarse and fine channel position values ​​are also recorded as zero.

[0033] Apstc1=0.0;Apstj1=0.0;

[0034] Apstc = 0.0; Apstj = 0.0.

[0035] 8) The turntable continues to rotate, and the values ​​of the coarse and fine channels are recorded in real time and assigned to Apstc and Apstj respectively. The values ​​are then combined according to the algorithm to form the current position of the turntable, Apst.

[0036] 9) Differentiate and filter the position value Apst to obtain the velocity value;

[0037] 10) In this embodiment, a light-shielding plate and a photoelectric sensor are used as the hardware generator for the zeroing signal. The light-shielding plate enters the photoelectric sensor in two directions, which is determined by the velocity value: positive (velocity value is positive) and negative (velocity value is negative).

[0038] 6) The photoelectric sensor is powered by +5V. When the light-shielding plate enters the photoelectric sensor, it blocks the sensor, and the sensor outputs a high level. When the light-shielding plate is removed from the photoelectric sensor, the sensor outputs a low level. If the width of the light-shielding plate is too narrow, the blocking will be incomplete, and the output level of the photoelectric sensor will be unclear. Therefore, the light-shielding plate should be approximately 3mm wide. This width will introduce randomness during the turntable's zeroing process within the high-level range.

[0039] 7) To eliminate the randomness of clearing, the rising or falling edge when the level changes is used as the clearing flag, and the position where the positive velocity moves out and the position where the negative velocity enters are close to the same position.

[0040] 8) In this embodiment, the positive falling edge, i.e. the negative rising edge, is taken as the zeroing flag. When the falling edge of the photoelectric sensor is read, the current resolver value is subtracted as the zero bias value and assigned the following values: Apstc1 = Apstc, Apstj1 = Apstj.

[0041] 9) Multiply the read resolver value by K to obtain the turntable position value. The turntable automatically resets to zero at the falling edge of the photoelectric sensor after each rotation, eliminating accumulated errors from multiple rotations.

[0042] 10) The process of obtaining the K value:

[0043] Mount the turntable under test onto a high-precision position calibration turntable, and measure the angle value output by the resolver after one revolution of the turntable. Perform 3 to 5 measurements, calculate the average value of the angle samples, and calculate the scale K value, K = 360 / resolver output angle. This value corrects the feedback value of the position sensor of the 2D turntable, improving the sensor sampling accuracy.

[0044] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for zeroing the cumulative error of a sensor under arbitrary mechanical transmission ratio, characterized in that, A light-shielding plate with a width of 3-4 mm is installed on the rotating shaft. The light-shielding plate rotates with the rotating shaft. A photoelectric sensor is installed on the non-rotating frame as a signal generator to generate a cumulative error clearing signal. For a turntable that rotates continuously 360° for a long time, the rising or falling edge of the photoelectric sensor is used as the clearing mark. After each rotation, the zero bias is automatically cleared to eliminate the cumulative error caused by multiple rotations. A coarse and fine channel is formed by combining two rotary transformers, and the angle after combination is the final position value. Includes the following steps: 1) Set four variables: the previous coarse channel zero-position raw value Apstc1, the previous fine channel zero-position raw value Apstj1, the current coarse channel position value Apstc, and the current fine channel position value Apstj; 2) During the rotation of the turntable, when it first passes the falling edge of the photoelectric sensor, the original values ​​of the coarse channel zero position and the fine channel zero position are recorded as zero, and the current coarse channel position value and the current fine channel position value are also recorded as zero, that is: Apstc1 = 0.0; Apstj1 = 0.0; Apstc = 0.0; Apstj = 0.0 3) The turntable continues to rotate, and the values ​​of the coarse and fine channels are recorded in real time and assigned to Apstc and Apstj respectively. The values ​​are then combined according to the algorithm to form the current position of the turntable, Apst. 4) Differentiate and filter the position value Apst to obtain the velocity value; 5) A light-shielding plate and a photoelectric sensor are used as the hardware generator for the zeroing signal; the light-shielding plate enters the photoelectric sensor in two directions, which are determined by the speed value, i.e., positive and negative. 6) The power supply for the photoelectric sensor is +5V. When the light-shielding plate enters the photoelectric sensor, it blocks the photoelectric sensor, and the output of the photoelectric sensor is high level; when the light-shielding plate is removed from the photoelectric sensor, the output of the photoelectric sensor is low level.

2. The method as described in claim 1, characterized in that, The falling edge is used as the zeroing mark. After the falling edge of the photoelectric sensor is read, the current resolver value is subtracted from the zero bias value, and this is taken as the zero point of the resolver. The read resolver value is multiplied by K to obtain the position value of the turntable. K is the scale value, which corrects the feedback value of the position sensor of the two-dimensional turntable. The turntable is automatically zeroed at the falling edge of the photoelectric sensor every time it rotates.

3. The method as described in claim 1 or 2, characterized in that, The process of obtaining the K value includes the following steps: the turntable under test is installed on the position calibration turntable, the angle value output by the resolver is measured after one revolution of the turntable under test, 3 to 5 measurements are performed, the average value of the angle sampling is obtained, and the scale value K is calculated, K=360 / resolver output angle.

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