High-precision micro linear actuator dual-encoder position compensation method and system

Abstract

The application provides a high-precision micro linear actuator double-encoder position compensation method and system, adopts a motor end encoder and a load end linear encoder double-feedback hardware architecture, combines a high-precision temperature sensor, constructs a cascade double-closed-loop control system, obtains transmission chain basic characteristic parameters through parameter calibration, sequentially completes inner loop speed current closed loop and outer loop position compensation closed loop debugging, integrates back gap compensation, LuGre friction compensation and thermal error feedforward compensation multi-module algorithms, and integrally compensates transmission chain nonlinear errors and environmental errors, introduces an adaptive iterative optimization mechanism, and dynamically corrects compensation parameters according to historical positioning deviations. The application solves the problems of traditional single-encoder control mode errors, low positioning accuracy, single full-closed-loop control poor dynamic response and easy oscillation, and realizes sub-micron high-precision positioning of the micro linear actuator under complex working conditions such as wide temperature range, variable load, high-low speed switching and the like.

Description

Technical Field

[0001] This invention relates to the field of precision motion control technology, and in particular to a high-precision micro linear actuator dual encoder position compensation method and system for high-precision manufacturing fields such as semiconductor bonding, optical lens fine adjustment, and minimally invasive medical devices. Background Technology

[0002] Precision linear drive technology is a core foundational technology for strategic emerging industries such as high-end equipment manufacturing, advanced optoelectronics, semiconductor processing, minimally invasive medicine, and micro / nano robotics. As modern manufacturing evolves towards micro / nano scale, ultra-high positioning accuracy, high dynamic response, and wide adaptability to various operating conditions, traditional drive actuators can no longer meet the precision motion control demands at the sub-micron and even nanometer levels. As a core component for achieving minute-scale linear motion, the micro-linear actuator, with its small size, high integration, smooth transmission, and flexible control, is widely used in precision alignment, micro-feeding, optical focusing, precision injection, and chip bonding. Its positioning accuracy, repeatability, and motion stability directly determine the overall equipment's process capability and product yield.

[0003] Currently, mainstream miniature linear actuators in the industry generally adopt a transmission architecture of "servo / stepper motor, reduction mechanism and ball screw", relying on encoders to achieve closed-loop position control. Due to multiple factors such as machining, assembly errors, transmission pair backlash, elastic deformation, friction characteristics, and ambient temperature changes, the transmission link introduces complex nonlinear and time-varying errors. A single control mode and a single detection feedback method have become common bottlenecks restricting further improvements in the accuracy of miniature linear actuators.

[0004] Existing micro linear actuator position control technologies mainly include the following three types of solutions: The single-motor-end encoder semi-closed-loop control scheme: An angular displacement encoder is installed coaxially only at the tail of the drive motor. The theoretical linear displacement of the load is indirectly calculated through the motor angle, reduction ratio, and lead screw lead. This scheme has a simple structure, low cost, and fast motor dynamic response, but it cannot detect the actual error of the transmission chain. Backlash, elastic deformation, lead screw pitch error, and thermal drift error are all superimposed on the positioning result. In the low-speed range, motion crawling and position lag are prone to occur, and the repeatability of positioning is generally only ±0.1~±0.5μm, which cannot meet the requirements of sub-micron level ultra-high precision.

[0005] Single-load linear encoder full closed-loop control scheme: This scheme eliminates the motor-end position closed loop and only installs a linear encoder / magnetic encoder on the sliding load platform side, using the actual load position as the sole feedback signal. While this scheme offers high static positioning accuracy, it lacks high-speed and current feedback from the motor, resulting in low system control bandwidth. It is prone to oscillations, overshoot, and jitter during high-speed start-stop and reciprocating motion, placing high demands on the controller's computing power and significantly increasing hardware costs. It cannot simultaneously handle high-speed dynamic motion and high-precision positioning.

[0006] Single encoder and single error compensation algorithm solution: Based on the semi-closed-loop architecture of a single motor-end encoder, add a simple backlash compensation, friction compensation, or single-point temperature compensation module. This solution has low modification cost, but it only compensates for a single error source and cannot solve the problem of multiple error coupling. The compensation parameters are mostly fixed values, which cannot adapt to changes in load, temperature, and speed, and the improvement in positioning accuracy is limited.

[0007] In summary, existing technologies suffer from the following common shortcomings: a single feedback method, failing to simultaneously address both the high dynamic response of the motor and the high-precision true-value detection of the load position; the lack of a comprehensive transmission chain error model, preventing integrated compensation for multiple types of errors; fixed compensation parameters, leading to severe accuracy degradation under complex operating conditions; and a low accuracy ceiling, making it difficult to meet the stringent sub-micron positioning requirements of high-end equipment. Therefore, developing a control compensation method that balances dynamic response performance with high-precision positioning capabilities and can comprehensively compensate for multiple types of errors has become an urgent need for the technological upgrade of micro linear actuators. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing micro linear actuator position control schemes, which cannot simultaneously achieve high dynamic response and ultra-high positioning accuracy, have poor multi-error coupling compensation effects, and have weak adaptability to working conditions. This invention provides a high-precision micro linear actuator dual-encoder position compensation method and system, which combines dual-encoder dual-feedback cascade dual-closed-loop control with multi-module integrated error compensation to achieve sub-micron level high-precision stable positioning of micro linear actuators under all working conditions.

[0009] According to one objective of the present invention, a high-precision micro linear actuator dual encoder position compensation method is provided, comprising the following steps: Hardware assembly: A motor-end encoder is coaxially mounted at the tail of the drive motor of the miniature linear actuator, a load-end linear encoder is mounted on the sliding load platform side, an NTC high-precision temperature sensor is fitted onto the lead screw base, and all sensor signals are connected to a dedicated motion controller. Parameter calibration: Input the basic parameters of the micro linear actuator into the motion controller, complete the dual encoder pulse equivalent calibration and signal synchronization calibration, and calibrate the transmission chain backlash threshold, static friction threshold and dynamic friction threshold through motion testing; Dual closed-loop hierarchical control debugging: First, activate the speed and current inner loop and tune the inner loop PID parameters to ensure the dynamic response performance of the motor; then activate the position compensation outer loop and tune the outer loop PID parameters based on the feedback data from the linear encoder at the load end to eliminate the basic positioning deviation. Multi-module error compensation: The backlash compensation module, LuGre friction compensation module and thermal error feedforward compensation module are activated in sequence to perform real-time dynamic compensation for transmission backlash error, low-speed friction crawling error and lead screw thermal drift error, respectively. Adaptive iterative optimization: The motion controller periodically collects steady-state position deviation data and automatically fine-tunes the threshold parameters and compensation coefficients of each compensation module to achieve adaptive adaptation under all working conditions.

[0010] Furthermore, in step 1, the motor-end encoder is a 21-bit magnetoelectric coaxial encoder with an angular resolution of not less than 0.001° and a sampling frequency of not less than 15kHz; the load-end linear encoder is a 28-bit miniature grating ruler with a displacement resolution of not less than 0.05μm and a sampling frequency of not less than 3kHz; and the NTC high-precision temperature sensor has a temperature measurement accuracy of not less than ±0.1℃.

[0011] Furthermore, in step 2, the basic parameters include the lead screw, reduction ratio, and lead screw thermal expansion coefficient; the synchronization error of the dual encoder signal synchronous calibration does not exceed 1μs; the transmission chain backlash threshold is calibrated through forward and reverse reciprocating motion tests, and the static friction threshold and dynamic friction threshold are calibrated through low-speed climbing experiments.

[0012] Furthermore, in step 3, after the inner loop PID parameters are tuned, the steady-state speed fluctuation of the motor at the rated speed does not exceed 0.3%, and there is no obvious lag or oscillation during start-up and shutdown; after the outer loop PID parameters are tuned, the initial repeatability of the micro linear actuator is not less than ±0.2μm.

[0013] Furthermore, in step 4, the backlash compensation module operates as follows: the controller monitors the actuator's movement direction in real time; when the position error at the moment of commutation exceeds the calibrated backlash threshold, it automatically superimposes a reverse compensation pulse equal to the backlash threshold to offset the commutation backlash error; when the movement direction is constant, the backlash compensation module automatically goes into sleep mode.

[0014] Furthermore, in step 4, the LuGre friction compensation module is activated in the low-speed range where the actuator's movement speed is ≤0.5mm / s. Based on the calibrated static friction threshold and dynamic friction threshold, it predicts the friction change node and superimposes a dynamic compensation amount of 0.1~0.3μm to eliminate the low-speed crawling phenomenon.

[0015] Furthermore, in step 4, the thermal error feedforward compensation module uses 25°C as the initial reference temperature, collects the temperature difference of the lead screw base in real time, calculates the thermal expansion and contraction amount by combining the effective stroke of the lead screw and the coefficient of thermal expansion, and adds it to the position command in advance for compensation.

[0016] Furthermore, in step 5, the triggering condition for the adaptive iterative optimization is: the motion controller completes 100 positioning actions; the parameter correction includes: fine-tuning the backlash threshold, friction compensation amount and thermal error compensation ratio according to the mean steady-state position deviation, automatically increasing the elastic deformation compensation coefficient under heavy load conditions, and optimizing the thermal error compensation coefficient under high temperature conditions.

[0017] Furthermore, the miniature linear actuator is a miniature ball screw linear actuator with a stroke of 10 mm, a lead of 0.5 mm, and a reduction ratio of 10; the coefficient of thermal expansion of the screw is 11.5 ppm / ℃, and for every 5℃ increase in temperature, the thermal error feedforward compensation module automatically compensates for 0.14 μm of thermal deformation error.

[0018] According to another objective of the present invention, the present invention provides a system for implementing the above-described high-precision micro linear actuator dual encoder position compensation method, comprising: The miniature linear actuator body includes a drive motor, a reduction mechanism, a miniature ball screw, and a sliding load platform; The dual encoder detection unit includes a motor-end encoder coaxially mounted at the tail of the drive motor and a load-end linear encoder mounted on the side of the sliding load platform. The temperature detection unit is an NTC high-precision temperature sensor that is fitted and mounted on the lead screw base. The motion controller is electrically connected to the dual encoder detection unit, temperature detection unit, and drive motor, and has a built-in cascade dual closed-loop control module, multi-module error compensation unit, and adaptive iterative optimization module.

[0019] The technical solution of this invention fundamentally solves the core contradictions of traditional single-encoder semi-closed-loop control, which cannot detect transmission chain errors and has poor dynamic response, by combining a dual-encoder dual-feedback architecture at the motor and load ends with cascaded dual-closed-loop control. It simultaneously ensures both high-speed dynamic performance and high-precision detection of the actual position at the load end. Through multi-module integrated error compensation, it systematically eliminates various coupling errors such as transmission backlash, low-speed friction creep, and lead screw thermal drift. Combined with an adaptive iterative optimization mechanism, the compensation parameters are dynamically adjusted according to the operating conditions, significantly improving positioning stability under complex conditions. This meets the stringent requirements of high-end fields such as semiconductors and optics for sub-micron-level high-precision positioning of micro linear actuators. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the hardware assembly structure of the high-precision miniature linear actuator dual encoder position compensation system according to an embodiment of the present invention; Figure 2 This is a flowchart of the high-precision micro linear actuator dual encoder position compensation method according to an embodiment of the present invention; Figure 3 This is a block diagram illustrating the transmission chain error decomposition and compensation principle of an embodiment of the present invention; Figure 4 This is a structural block diagram of the cascaded dual closed-loop control system according to an embodiment of the present invention.

[0022] In the diagram: 1. Drive motor; 2. Motor-end encoder; 3. Reduction mechanism; 4. Miniature ball screw; 5. Sliding load platform; 6. Load-end linear encoder; 7. Temperature sensor; 8. Motion controller. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] Example 1 like Figures 1-4 As shown, this embodiment provides a high-precision miniature linear actuator dual-encoder position compensation method, applied to a miniature ball screw linear actuator with a stroke of 10mm, a lead of 0.5mm, and a reduction ratio of 10. The specific steps are as follows: Step 1: Hardware Assembly like Figure 1 As shown, a 21-bit magnetoelectric motor-end encoder 2 is coaxially mounted at the tail of the drive motor 1, with an angular resolution of 0.001° and a sampling frequency of 15kHz; a 28-bit miniature grating ruler is mounted on the side of the sliding load platform 5 as a load-end linear encoder 6, with a displacement resolution of 0.05μm and a sampling frequency of 3kHz; an NTC high-precision temperature sensor 7 is attached to the bottom surface of the base of the miniature ball screw 4, with a temperature measurement accuracy of ±0.1℃; the signal output terminals of the motor-end encoder 2, the load-end linear encoder 6, and the temperature sensor 7 are all connected to a dedicated motion controller 8, and the output terminal of the motion controller 8 is connected to the driver of the drive motor 1, thus completing the hardware system setup.

[0027] Step 2: Parameter Calibration Input the basic parameters of the micro linear actuator into the motion controller 8: lead screw 0.5mm, reduction ratio 10, and lead screw thermal expansion coefficient 11.5ppm / ℃.

[0028] Dual encoder pulse equivalent calibration: Control drive motor 1 to drive sliding load platform 5 to perform full-stroke reciprocating motion, collect the pulse count of encoder 2 at the motor end and the displacement data of linear encoder 6 at the load end respectively, and calculate the pulse equivalent of encoder 2 at the motor end as 0.5mm / (10×2^21)≈2.38×10^-8mm / pulse, and the pulse equivalent of linear encoder at the load end as 0.05μm / pulse.

[0029] Signal synchronization calibration: The sampling clock of the dual encoders is adjusted by the hardware synchronization trigger function of the motion controller 8 so that the signal synchronization error between the two encoders is ≤1μs.

[0030] Backlash threshold calibration: Control the sliding load platform 5 to perform forward and reverse reciprocating motion at a speed of 0.1 mm / s, record the amount of backlash detected by the linear encoder 6 at the load end at the moment of reversal, take the average value of multiple measurements, and calibrate the backlash threshold of the transmission chain to 2 μm.

[0031] Friction threshold calibration: A low-speed climbing test was conducted, and the output torque of the motor was gradually increased. The torque value when the sliding load platform 5 started to move was recorded, and the static friction threshold was calculated to be 0.3N. The torque value when the platform moved at a constant speed was recorded, and the dynamic friction threshold was calculated to be 0.1N.

[0032] Step 3: Dual Closed-Loop Layered Control Debugging This invention employs a cascaded dual-closed-loop control architecture, such as... Figure 4 As shown, the inner loop is the velocity current loop, and the outer loop is the position compensation loop.

[0033] Inner loop tuning: Enable speed-current closed loop, disable outer loop compensation and all compensation modules, and tune the inner loop PID parameters using the Ziegler-Nichols method. After tuning, the motor's steady-state speed fluctuation at rated speed of 3000 rpm is ≤0.3%, the start-stop response time is ≤10ms, and there is no obvious lag or oscillation.

[0034] Outer loop tuning: The position compensation closed loop is activated, and the outer loop PID parameters are tuned based on feedback data from the linear encoder 6 at the load end. After tuning, the initial repeatability of the miniature linear actuator under normal temperature no-load conditions reaches ±0.2μm.

[0035] Step 4: Multi-module error compensation like Figure 3 As shown, the overall error of the transmission chain is decomposed into backlash error, frictional hysteresis error, thermal drift error, elastic deformation error and pitch accumulation error, and compensated separately through a multi-module algorithm.

[0036] Backlash compensation: The controller monitors the motion direction signal in real time. When a commutation is detected, the current position error is calculated immediately. If the error exceeds the 2μm backlash threshold, a 2μm reverse compensation pulse is automatically added to the motor control command to offset the commutation backlash error. When the motion direction remains constant, the backlash compensation module automatically goes into sleep mode to reduce the controller's computing power consumption.

[0037] LuGre Friction Compensation: When the actuator's movement speed is ≤0.5mm / s, the LuGre friction compensation module is automatically activated. Based on the calibrated static and dynamic friction thresholds, this module establishes a LuGre friction model, predicts the abrupt transition points between static and dynamic friction, and pre-adds a dynamic compensation amount of 0.1~0.3μm to completely eliminate low-speed crawling.

[0038] Thermal error feedforward compensation: Using 25℃ as the initial reference temperature, temperature sensor 7 collects the temperature T of the lead screw base in real time, and calculates the temperature difference ΔT = T - 25℃. Based on the effective stroke L = 10mm of the lead screw and the coefficient of thermal expansion α = 11.5ppm / ℃, the thermal expansion ΔL = α × L × ΔT is calculated. ΔL is pre-added to the original position command to achieve thermal error feedforward compensation. In this embodiment, for every 5℃ increase in temperature, a thermal deformation error of 0.14μm is automatically compensated.

[0039] Step 5: Adaptive Iterative Optimization Every 100 positioning actions completed, the motion controller 8 automatically collects the steady-state position deviation data from the most recent 100 actions, and calculates the mean and standard deviation of the deviation. Based on the calculation results, it automatically fine-tunes the parameters of each compensation module. If the mean steady-state position deviation is biased in a certain direction, fine-tune the backlash compensation threshold and the friction compensation amount. If the elastic deformation error increases under heavy load conditions, the elastic deformation compensation coefficient will be automatically increased. If the accuracy of thermal error compensation decreases under high-temperature conditions, optimize the thermal error compensation ratio coefficient.

[0040] Through the above adaptive iterative optimization, the compensation parameters are always matched to the current working conditions, ensuring the positioning accuracy of the system under all working conditions.

[0041] Implementation effect test The performance of the modified miniature linear actuator in this embodiment was tested, and the test results are as follows: Under normal temperature (25℃) no-load conditions, the repeatability of positioning can reach ±0.015μm, and the absolute positioning accuracy is 0.08μm; Within a wide temperature range of -10℃ to 60℃, the positioning accuracy fluctuation is ≤0.03μm; There is no crawling phenomenon under low-speed (0.01mm / s) fine-tuning conditions, and no oscillation or overshoot under high-speed (50mm / s) reciprocating motion conditions; Under heavy load (rated load 50N), the repeatability accuracy remains within ±0.02μm.

[0042] Its overall performance is far superior to traditional single encoder control schemes, and it can meet the submicron-level ultra-high precision positioning requirements of high-end scenarios such as semiconductor bonding and optical lens fine adjustment.

[0043] Compared with the prior art, the present invention has the following beneficial effects: This invention balances high dynamic response and ultra-high positioning accuracy: it adopts a dual encoder and dual feedback architecture at the motor end and the load end, combined with a cascade dual closed-loop control strategy. The inner loop relies on the encoder at the motor end to ensure high-speed dynamic performance, while the outer loop relies on the encoder at the load end to ensure positioning accuracy, thus completely solving the defect of existing technologies that cannot simultaneously achieve both dynamic response and high-precision positioning.

[0044] This invention achieves comprehensive compensation for multiple types of errors, significantly improving environmental adaptability: by adding a temperature detection unit and combining it with multi-module algorithms such as backlash compensation, LuGre friction compensation, and thermal error feedforward compensation, it can perform integrated compensation for transmission chain coupling errors and environmental temperature errors. Within a wide temperature range of -10℃ to 60℃, the positioning accuracy fluctuation does not exceed 0.03μm.

[0045] This invention features intelligent error compensation and a wider range of working conditions adaptability: it adds an adaptive iterative optimization mechanism that can dynamically correct compensation parameters based on historical positioning deviations, enabling it to adapt to different usage scenarios such as no-load, heavy-load, and continuous operation, thus greatly expanding its robustness and applicability.

[0046] The detection and control logic of this invention is clearly layered, resulting in higher operational stability: by adopting cascaded layered control, the speed current loop and the position compensation loop are separated, each performing its own function, which strengthens the system's anti-interference capability and ensures that there is no drift or instability during long-term continuous operation.

[0047] This invention is highly practical for engineering applications and has low modification costs: it requires no structural changes to the mechanical body of the micro linear actuator, and the accuracy can be upgraded simply by adding sensors and upgrading the control algorithm. It requires minimal hardware modifications, has a simple calibration process, and can be quickly adapted to existing mainstream micro linear actuators, giving it significant advantages for industrialization and promotion.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-precision micro linear actuator dual encoder position compensation method, characterized in that, Includes the following steps: Hardware assembly: A motor-end encoder is coaxially mounted at the tail of the drive motor of the miniature linear actuator, a load-end linear encoder is mounted on the sliding load platform side, an NTC high-precision temperature sensor is fitted onto the lead screw base, and all sensor signals are connected to a dedicated motion controller. Parameter calibration: Input the basic parameters of the micro linear actuator into the motion controller, complete the dual encoder pulse equivalent calibration and signal synchronization calibration, and calibrate the transmission chain backlash threshold, static friction threshold and dynamic friction threshold through motion testing; Dual closed-loop hierarchical control debugging: First, activate the speed and current inner loop and tune the inner loop PID parameters to ensure the dynamic response performance of the motor; then activate the position compensation outer loop and tune the outer loop PID parameters based on the feedback data from the linear encoder at the load end to eliminate the basic positioning deviation. Multi-module error compensation: The backlash compensation module, LuGre friction compensation module and thermal error feedforward compensation module are activated in sequence to perform real-time dynamic compensation for transmission backlash error, low-speed friction crawling error and lead screw thermal drift error, respectively. Adaptive Iterative Optimization: The motion controller periodically collects steady-state position deviation data and automatically fine-tunes the threshold parameters and compensation coefficients of each compensation module to achieve adaptive adaptation under all working conditions.

2. The high-precision micro linear actuator dual encoder position compensation method according to claim 1, characterized in that, In step 1, the motor-end encoder is a 21-bit magnetoelectric coaxial encoder with an angle resolution of not less than 0.001° and a sampling frequency of not less than 15kHz; the load-end linear encoder is a 28-bit miniature grating ruler with a displacement resolution of not less than 0.05μm and a sampling frequency of not less than 3kHz; and the NTC high-precision temperature sensor has a temperature measurement accuracy of not less than ±0.1℃.

3. The high-precision micro linear actuator dual encoder position compensation method according to claim 1, characterized in that, In step 2, the basic parameters include lead screw lead, reduction ratio, and lead screw thermal expansion coefficient; the synchronization error of the dual encoder signal synchronous calibration does not exceed 1μs; the transmission chain backlash threshold is calibrated through forward and reverse reciprocating motion test, and the static friction threshold and dynamic friction threshold are calibrated through low-speed climbing experiment.

4. The high-precision micro linear actuator dual encoder position compensation method according to claim 1, characterized in that, In step 3, after the inner loop PID parameters are tuned, the steady-state speed fluctuation of the motor at the rated speed does not exceed 0.3%, and there is no obvious lag or oscillation during start-up and shutdown; after the outer loop PID parameters are tuned, the initial repeatability of the micro linear actuator is not less than ±0.2μm.

5. The high-precision micro linear actuator dual encoder position compensation method according to claim 1, characterized in that, In step 4, the backlash compensation module works as follows: the controller monitors the actuator's movement direction in real time. When the position error at the moment of commutation exceeds the calibrated backlash threshold, it automatically superimposes a reverse compensation pulse equal to the backlash threshold to offset the commutation backlash error. When the movement direction is constant, the backlash compensation module automatically goes into sleep mode.

6. The high-precision micro linear actuator dual encoder position compensation method according to claim 1, characterized in that, In step 4, the LuGre friction compensation module is activated in the low-speed range where the actuator's movement speed is ≤0.5mm / s. Based on the calibrated static friction threshold and dynamic friction threshold, it predicts the friction change node and superimposes a dynamic compensation amount of 0.1~0.3μm to eliminate the low-speed crawling phenomenon.

7. The high-precision micro linear actuator dual encoder position compensation method according to claim 1, characterized in that, In step 4, the thermal error feedforward compensation module uses 25℃ as the initial reference temperature, collects the temperature difference of the lead screw base in real time, calculates the thermal expansion and contraction amount by combining the effective stroke of the lead screw and the coefficient of thermal expansion, and adds it to the position command in advance for compensation.

8. The high-precision micro linear actuator dual encoder position compensation method according to claim 1, characterized in that, In step 5, the triggering condition for the adaptive iterative optimization is: the motion controller completes 100 positioning actions; the parameter correction includes: fine-tuning the backlash threshold, friction compensation amount and thermal error compensation ratio according to the mean steady-state position deviation, automatically increasing the elastic deformation compensation coefficient under heavy load conditions, and optimizing the thermal error compensation coefficient under high temperature conditions.

9. The high-precision micro linear actuator dual encoder position compensation method according to claim 1, characterized in that, The miniature linear actuator is a miniature ball screw linear actuator with a stroke of 10 mm, a lead of 0.5 mm, and a reduction ratio of 10; the coefficient of thermal expansion of the screw is 11.5 ppm / ℃, and for every 5℃ increase in temperature, the thermal error feedforward compensation module automatically compensates for a thermal deformation error of 0.14 μm.

10. A system for implementing the high-precision micro linear actuator dual encoder position compensation method according to any one of claims 1-9, characterized in that, include: The miniature linear actuator body includes a drive motor, a reduction mechanism, a miniature ball screw, and a sliding load platform; The dual encoder detection unit includes a motor-end encoder coaxially mounted at the tail of the drive motor and a load-end linear encoder mounted on the side of the sliding load platform. The temperature detection unit is an NTC high-precision temperature sensor that is fitted and mounted on the lead screw base. The motion controller is electrically connected to the dual encoder detection unit, temperature detection unit, and drive motor, and has a built-in cascade dual closed-loop control module, multi-module error compensation unit, and adaptive iterative optimization module.

Images