A method for reducing positioning chattering based on a given optimization of the encoder resolution

Abstract

The application provides a method for reducing positioning chattering based on encoder resolution given optimization, comprising the following steps: servo system initialization, the upper computer controls the servo system to carry out position closed loop, input external positioning given position, calculate intermediate floating point value, the servo system is based on P ref1 ° executes position closed loop control. The application is based on the encoder resolution of the servo system, modifies the positioning given position, eliminates the static difference between the given and the feedback caused by the limited encoder resolution, and eliminates the jumping caused by the simultaneous action of the static difference and the system integration.

Description

Technical Field

[0001] This invention relates to a method for optimizing and reducing positioning jitter based on encoder resolution, belonging to the field of motor servo control. Background Technology

[0002] Servo systems are widely used in industrial robots, drones, CNC machine tools and other equipment due to their excellent dynamic and steady-state performance. However, due to the use of elastic connection devices such as couplings and gearboxes in servo systems, residual jitter exists at the load end when the servo motor is positioned, which affects the positioning accuracy and can cause damage to machine tools and processing equipment in severe cases. Therefore, it is necessary to suppress the jitter during positioning.

[0003] In-depth research has been conducted both domestically and internationally on control methods for chatter suppression in servo systems. Generally, control methods include two types: active and passive suppression. Active suppression primarily eliminates resonance effects through adaptive control, including state-observation-based feedback control, self-tuning, and adaptive control. Passive methods mainly employ algorithms such as band-stop, low-pass filtering, and input shaping; the passive suppression mode is a feedforward control algorithm.

[0004] None of the above control methods address the resolution of the servo system, resulting in the following technical defects in the existing technology:

[0005] During positioning in the position loop, because the encoder resolution is limited, the steady-state error between the given position and the feedback can only be zero after the servo system completes the position loop if the given positioning position is an integer multiple of the encoder resolution. Otherwise, the steady-state error between the given position and the feedback will always exist and cannot be eliminated. Due to the existence of the steady-state error, the servo system will bounce back and forth around the given position under the action of system integration. As a result, the lower the positioning accuracy, the more the servo system will jitter. When the encoder accuracy is lower, the error between the given position and the feedback will be larger, and the jitter amplitude will also be larger. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for reducing positioning jitter based on encoder resolution setting optimization. This method is simple and easy to implement, and while reducing positioning jitter in the servo system, it also improves the positioning accuracy of the servo system.

[0007] The present invention is achieved through the following technical solutions.

[0008] This invention provides a method for reducing positioning jitter based on a given encoder resolution, comprising the following steps:

[0009] ① Set the encoder resolution in the servo system to x bits, and the measurement stroke to... ;

[0010] ② Obtain the external positioning given position P input from the host computer. ref °;

[0011] ③Based on the encoder's resolution x and the measurement stroke and external positioning given position P ref °, calculates an intermediate floating-point value. ;

[0012] ④ For intermediate floating-point values Perform a floor operation to get the integer a;

[0013] ⑤ Calculate intermediate floating-point values The difference between the integer 'a' and 'a' is used to determine the optimal internal position given value P based on the relationship between this difference and 0.5. ref1 °, if If -a ≤ 0.5, then P ref1 ° = a * ( / );like - If a > 0.5, then P ref1 ° = (a + 1) * ( / );

[0014] ⑥ Set the internal position value P ref1 ° is used as the final setpoint of the servo system's position loop, replacing the external positioning setpoint P. ref °, the servo system is based on P ref1 °Execute position closed-loop control.

[0015] The encoder is an absolute encoder, used to detect the absolute position output by the end of the servo system.

[0016] The The calculation formula is: =(P ref ° * ) / , .

[0017] Calculating intermediate floating-point values and the internal position given value P ref1 When the effective decimal places are truncated to °, the effective decimal places truncated are consistent with those truncated when the servo system calculates the absolute position P° based on the encoder feedback value n.

[0018] The ,and n It is an integer.

[0019] The formula for calculating the absolute position P° of the servo system based on the encoder feedback value n is as follows:

[0020]

[0021]

[0022] in, This represents the position loop error.

[0023] The beneficial effects of this invention are as follows: Based on the encoder resolution of the servo system, the given position is modified to eliminate the steady-state error between the given position and the feedback caused by the limited encoder resolution, thereby eliminating the fluctuation caused by the simultaneous action of steady-state error and system integral. Attached Figure Description

[0024] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0025] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0026] like Figure 1 As shown, the servo system encoder has a resolution of 12 bits, a measurement stroke of 360°, and an encoder feedback value of , ,and The absolute position of the feedback is an integer. P °, external positioning given position is P ref °, the position loop error is P err °, For intermediate floating-point values, a If it is an integer, then:

[0027]

[0028]

[0029] To achieve each Down, Both equal 0, only by letting: .but Since this is an external input and cannot be modified, the internal position setpoint of the servo system position loop is set to... P ref1 °, according to Combined with encoder resolution P ref1 ° is used for the final position loop calculation.

[0030] When the host computer controls the servo system to perform position closed-loop, it inputs an external positioning command. When =100, let

[0031]

[0032] a for Rounding down, design calculation P If you truncate to 2 significant decimal places at °, then If the calculation is also truncated to two significant decimal places, then...

[0033]

[0034] right - a Make a judgment, if - a If ≤0.5, then let

[0035] P ref1 °

[0036] like a 1- a If the value is greater than 0.5, then let

[0037] P ref1 °

[0038] because a 1- a= 0.78 > 0.5, therefore

[0039] P ref1 ° =100.02

[0040] Finally, P ref1 ° Replacement P ref ° is given as the final position, and the servo system performs position closure based on 100.02°.

[0041] If the servo system performs closed-loop positioning based on a 100° setpoint, because the encoder resolution is only 12 bits, the servo system can only position itself to 100.02°. At this point, the steady-state error between the setpoint and feedback is 0.02°. Under the influence of system integration, the servo system will move towards 100°. However, due to the encoder resolution, the servo system can only position itself to 99.93°, resulting in a steady-state error of 0.07°. Under the influence of system integration, the servo system will move towards 100° again, eventually positioning itself to 100.02°. Due to the combined effects of steady-state error and system integration, the servo system will bounce back and forth around 100°, causing servo system jitter. When the positioning setpoint is changed to 100.02°, the steady-state error between the setpoint and feedback becomes 0°, thus eliminating the jitter caused by the simultaneous effects of steady-state error and system integration. Furthermore, compared to a 100° setpoint from the host computer, a 100.02° setpoint provides three times the accuracy of a 99.93° setpoint.

Claims

1. A method for reducing positioning jitter based on encoder resolution optimization, characterized in that: Includes the following steps: ① Set the encoder resolution in the servo system to x bits, and the measurement stroke to... ; ② Obtain the external positioning given position P input from the host computer. ref °; ③Based on the encoder's resolution x and the measurement stroke and external positioning given position P ref °, calculates an intermediate floating-point value. The The calculation formula is: =(P ref ° * ) / , ; ④ For intermediate floating-point values Perform a floor operation to get the integer a; ⑤ Calculate intermediate floating-point values The difference between the integer 'a' and 'a' is used to determine the optimal internal position given value P based on the relationship between this difference and 0.

5. ref1 °, if If -a ≤ 0.5, then P ref1 ° = a * ( / );like If - a > 0.5, then P ref1 ° = (a + 1) * ( / ); ⑥ Set the internal position value P ref1 ° is used as the final setpoint of the servo system's position loop, replacing the external positioning setpoint P. ref °, the servo system is based on P ref1 °Execute position closed-loop control.

2. The method for reducing positioning jitter based on encoder resolution as described in claim 1, characterized in that: The encoder is an absolute encoder, used to detect the absolute position output by the end of the servo system.

3. The method for reducing positioning jitter based on encoder resolution optimization as described in any one of claims 1 to 2, characterized in that: Calculating intermediate floating-point values and the internal position given value P ref1 When the effective decimal places are truncated to °, the effective decimal places truncated are consistent with those truncated when the servo system calculates the absolute position P° based on the encoder feedback value n.

4. The method for reducing positioning jitter based on encoder resolution as described in claim 3, characterized in that: The ,and n It is an integer.

5. The method for reducing positioning jitter based on encoder resolution as described in claim 3, characterized in that: The formula for calculating the absolute position P° of the servo system based on the encoder feedback value n is as follows: in, This represents the position loop error.

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