Driving control system and position compensation method of ultra-low-speed high-precision rotary table

Abstract

The invention relates to a drive control system and a position compensation method for an ultra-low-speed high-precision rotary table, and aims to solve the problem that the positioning precision of the rotary table is reduced due to transmission errors of a harmonic reducer during ultra-low-speed operation. The position error dynamic compensation is realized by respectively installing encoders at a motor end and an output end, constructing a transmission error observer, adopting a feed-forward compensation control strategy and combining an extended Kalman filter and a linear interpolation algorithm. Experiments show that the algorithm can reduce the position error by about 82%, significantly improves the positioning precision of the ultra-low-speed high-precision turntable system, and is suitable for ultra-low-speed application scenes with extremely high positioning precision requirements, such as laser radar continuous scanning and precision optical detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultra-low-speed and high-precision turntable control, and relates to a drive control system and a position compensation method for an ultra-low-speed and high-precision turntable, and in particular to a control system and a position compensation method for an ultra-low-speed and high-precision turntable based on a dual encoder. Background Art

[0002] An ultra-low-speed, high-precision turntable is a precision motion control device capable of achieving sub-arcsecond angular position accuracy at extremely low rotational speeds. Its core goal is to address the positioning deviation and speed fluctuations caused by friction, transmission errors, and other factors that plague traditional turntables at low speeds. It is widely used in fields requiring extremely smooth motion and repeatability, such as aerospace, semiconductor and optical inspection, and precision manufacturing. The main components of an ultra-low-speed, high-precision turntable are a motor as the drive mechanism and a harmonic reducer as the turntable's transmission structure.

[0003] A permanent magnet synchronous motor (PMSM) is a motor whose rotor, excited by permanent magnets, rotates synchronously with the stator magnetic field. Due to its high efficiency and power density, it has been widely used in a variety of key applications, including rail transportation equipment, robotics, and aerospace. Compared to traditional induction motors, PMSMs offer superior energy efficiency within the partial load range, helping to reduce overall energy consumption while maintaining high efficiency and power factor under light load conditions. Furthermore, PMSMs offer high flux density and fast dynamic response, making them uniquely advantageous in applications requiring high speed and rapid response. Advances in permanent magnet material technology, particularly rare earth materials, and reduced production costs have further enhanced the performance of PMSMs while simultaneously reducing their production costs. With the advancement of advanced control strategies such as direct torque control, variable voltage and frequency control, and vector control, the speed regulation range, control accuracy, and stability of PMSMs have been significantly improved, expanding their application in high-precision, high-efficiency applications, with particular strength in ultra-low-speed and high-precision control scenarios. However, permanent magnet synchronous motors (PMSMs) are subject to multiple nonlinear disturbances at ultra-low speeds. These disturbances interact with each other, significantly reducing position control accuracy. This problem often creates a dilemma for turntable systems in ultra-low-speed applications such as continuous LiDAR scanning and precision optical inspection, where they struggle to balance dynamic response and steady-state accuracy.

[0004] At the same time, the harmonic reducer, which serves as the turntable's transmission structure, also has transmission errors, resulting in persistent errors in the turntable's positioning. The harmonic reducer typically transmits torque through the interaction of a wave generator, a flexible ring, and a rigid wheel. However, since the flexible ring deforms during operation, periodic deformation errors occur during the transmission process. These deformation errors are amplified during ultra-low-speed operation, causing positioning errors in the turntable system. Specifically, this transmission error leads to a decrease in the system's rotational accuracy, which in turn causes positioning deviations and reduced repeatability when the turntable performs precision scanning tasks.

[0005] There is an urgent need for a drive control system and position compensation method for an ultra-low-speed, high-precision turntable to effectively improve the positioning accuracy of the ultra-low-speed, high-precision turntable system. Summary of the Invention

[0006] The purpose of the present invention is to provide a drive control system and position compensation method for an ultra-low-speed, high-precision turntable. Based on an in-depth analysis of the generation mechanism and propagation characteristics of multi-source disturbances in permanent magnet synchronous motors under ultra-low-speed conditions, the control architecture is optimized to provide greater adaptability. A position compensation method is proposed by systematically analyzing the impact of harmonic reducers on motor operation, thereby addressing the issue of reduced position control accuracy for ultra-low-speed, high-precision turntables. This purpose of the present invention is achieved through the following specific technical solutions.

[0007] A drive control system for an ultra-low-speed, high-precision turntable, comprising:

[0008] A permanent magnet synchronous motor is used to power the turntable. With its high efficiency and power density, it can maintain high efficiency and power factor even at ultra-low speeds, providing stable power support for the turntable system and meeting the requirements of high-precision control.

[0009] The motor-side control circuit board (PCB) connects to the permanent magnet synchronous motor and controls its operation. It precisely adjusts the motor's speed and torque, enabling precise speed regulation and ensuring the motor operates according to the predetermined control strategy. It is a crucial component in achieving high-precision position control in turntable systems.

[0010] The motor-end encoder and its code disk, installed at the end of the permanent magnet synchronous motor's shaft, detect the motor's position. They accurately capture position data, such as the motor shaft's rotation angle, in real time. This provides precise motor-end position feedback to the position compensation algorithm, ensuring accurate and timely position compensation.

[0011] The harmonic reducer, connected to the permanent magnet synchronous motor, is used to transmit torque and achieve deceleration. With its compact structure, high transmission accuracy, and large reduction ratio, the harmonic reducer can achieve high-reduction ratio motion conversion within a limited space while maintaining high transmission accuracy, providing excellent transmission performance for the ultra-low-speed, high-precision operation of the turntable.

[0012] The output encoder, along with its code disc and slip ring, is installed at the end of the turntable to detect the output position. This encoder, along with its code disc and slip ring, accurately measures the actual position of the turntable end, providing position data to the position compensation algorithm. This facilitates calculation and compensation of position errors, thereby improving the positioning accuracy of the turntable system.

[0013] Furthermore, the motor-side control circuit board integrates an STM32F446RE main control chip and a three-phase inverter drive circuit. The STM32F446RE main control chip has powerful processing capabilities and rich functions, capable of efficiently running control algorithms and processing various signals. The three-phase inverter drive circuit can convert direct current into three-phase alternating current, accurately controlling the operation of the permanent magnet synchronous motor, achieving precise speed regulation and stable operation of the motor, and improving the performance and reliability of the control system.

[0014] Furthermore, the motor-end encoder is a magnetic encoder, preferably a 17-bit magnetic encoder. A 17-bit magnetic encoder has a high resolution and can provide accurate motor-end position information. Its theoretical angular resolution reaches 0.0027°, providing a more detailed and accurate data foundation for the position compensation algorithm, helping to improve the accuracy and effectiveness of position compensation.

[0015] Furthermore, the output encoder is a photoelectric encoder, preferably a 26-bit photoelectric encoder. A 26-bit photoelectric encoder can provide highly accurate output position measurement data, further ensuring the accuracy of position error calculations, thereby making position compensation more precise and effectively improving the positioning accuracy of the turntable system, meeting the requirements of ultra-low-speed, high-precision application scenarios.

[0016] A position compensation method for an ultra-low-speed high-precision turntable comprises the following steps:

[0017] S1 installs high-precision position encoders at the turntable's motor end and at the output end after passing through the harmonic reducer. S2 uses these encoders to synchronously collect position data, monitor the position difference between the two ends in real time, and construct a transmission error observer. S3 uses the error information obtained by the transmission error observer and combines it with a feedforward compensation control strategy to achieve dynamic compensation for position error. By installing dual encoders at the motor and output ends, position data from both ends can be acquired in real time, accurately constructing a transmission error observer, and then dynamically compensating for position error. This effectively addresses the problem of reduced positioning accuracy caused by the harmonic reducer's transmission error during ultra-low-speed operation, improving the positioning accuracy of the turntable system.

[0018] Furthermore, the high-precision position encoder comprises a magnetic encoder mounted on the end of the motor shaft and a photoelectric encoder mounted on the output end of the turntable. This combination of magnetic and photoelectric encoders offers complementary advantages: the magnetic encoder offers excellent pollution resistance and high reliability, while the photoelectric encoder provides precise position measurement data. Together, they ensure high-precision and stable position data acquisition, providing a reliable basis for subsequent error compensation calculations and further improving positioning accuracy.

[0019] Furthermore, the real-time monitoring of the position difference between the two ends to construct a transmission error observer is specifically as follows: driving the turntable to rotate in a fixed direction for several cycles in a constant ultra-low speed mode, and recording the angle value θ of the encoder at the motor end m and the output encoder angle value θ out , the theoretical output position and position error Δθ=θ are obtained through real-time calculation out -(θ m / i), where i is the reduction ratio of the harmonic reducer. Data acquisition and calculation in constant ultra-low speed mode effectively prevents interference from factors such as speed fluctuations on error measurement. This allows the resulting position error Δθ to more accurately reflect the actual error of the transmission system, providing precise error information for subsequent compensation control and enhancing the compensation effect.

[0020] Furthermore, Δθ is converted to the motor end angle θ m To index the error lookup table, an extended Kalman filter is applied to the motor encoder data to reduce the impact of encoder accuracy on error calculations. Multi-turn data is averaged to suppress random noise. Storing the errors in the lookup table facilitates quick query and application of compensation values. The extended Kalman filter effectively handles noise and errors in the motor encoder data, improving data accuracy. Averaging multi-turn data further reduces random noise interference, making the data in the error lookup table more reliable and improving compensation stability and accuracy.

[0021] Furthermore, in real-time control, according to the current motor end angle θ mThe corresponding Δθ is obtained by querying the error lookup table, and the compensation resolution is improved through a linear interpolation algorithm. The compensation amount is directly added to the feedback channel of the position loop. By querying the error lookup table to obtain the corresponding compensation value and using a linear interpolation algorithm to improve the compensation resolution, the compensation is more refined and can more accurately compensate for the position error. The compensation amount is directly added to the feedback channel of the position loop, quickly and effectively correcting position deviations and improving the dynamic response and positioning accuracy of the turntable system.

[0022] The present invention has the following beneficial technical effects: by collecting the position data of the motor end and the output end through dual encoders, a transmission error observer is constructed, and combined with the feedforward compensation control strategy, the transmission error of the harmonic reducer can be effectively compensated, and the positioning accuracy of the ultra-low-speed high-precision turntable system can be significantly improved. Experiments show that after the position compensation algorithm is introduced, the position error is reduced by about 82%, so that the turntable system has higher positioning accuracy and stability when running at ultra-low speed, meeting the application scenarios with extremely high positioning accuracy requirements such as laser radar continuous scanning and precision optical detection. At the same time, a combination of magnetic grating encoders and photoelectric encoders is used to ensure the high accuracy and stability of position data acquisition; the extended Kalman filter and linear interpolation algorithm are used to further improve the accuracy and resolution of error compensation and optimize the compensation effect. The entire system is reasonably designed, and the various components work together to effectively solve the positioning accuracy problem during ultra-low-speed operation, and has good application prospects and market value. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the structural diagram of the harmonic reducer.

[0024] Figure 2 This is the working principle diagram of the harmonic reducer.

[0025] Figure 3 Schematic diagrams of different friction models: (a) Coulomb friction model, (b) Coulomb-static mixed friction model, (c) Coulomb-viscous mixed friction model, and (d) Stribeck friction model.

[0026] Figure 4 This is the block diagram of the position compensation control structure of the turntable system.

[0027] Figure 5a and Figure 5b This is a schematic diagram of the ultra-low speed and high precision turntable drive control system structure.

[0028] Figure 6 The overall design block diagram of the control scheme is given.

[0029] Figure 7 is the average position error graph.

[0030] Figure 8 This is the effect diagram of the position compensation algorithm.

[0031] Figure numerals: 1-rigid wheel, 2-flexible wheel, 3-wave generator, 4-motor control board, 5-motor stator, 6-harmonic reducer, 7-output end encoder PCB board fixing seat, 8-motor end encoder, 9-motor rotor assembly, 10-slip ring, 11-output end encoder fixing seat, 12-output end encoder, 13-base. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0033] In the description of the present invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate description and simplify the present invention. They are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance, quantity, or position.

[0034] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0035] A drive control system for an ultra-low-speed, high-precision turntable includes: a permanent magnet synchronous motor (PMSM) for providing the turntable's power source; a motor-end control circuit board (PCB) connected to the PMSM for controlling the motor's operation; a motor-end encoder and its code disk, mounted at the end of the PMSM's rotating shaft for detecting the motor's position; a harmonic reducer connected to the PMSM for transmitting torque and achieving deceleration; and an output-end encoder, its code disk, and slip ring, mounted at the end of the turntable for detecting the output's position. The motor-end control PCB integrates an STM32F446RE main control chip and a three-phase inverter drive circuit. The motor-end encoder is a 17-bit magnetic encoder, and the output-end encoder is a 26-bit photoelectric encoder.

[0036] The structure diagram of the harmonic reducer is as follows: Figure 1 As shown, its unique structural design and operating principle as a core component in the field of precision transmission demonstrate significant advantages in high-precision transmission applications such as robotic joints and aerospace precision mechanisms. From a structural design perspective, the device primarily consists of three core components: a wave generator 3, a flexspline 2, and a rigid pulley 1, forming a precisely coordinated system. The wave generator typically adopts an elliptical profile and is connected to the flexible transmission assembly via precision bearings. Its surface profile is machined to nanometer precision to ensure smooth motion. The flexspline, a key force transmission component, adopts a thin-walled cup-shaped structure made of high-strength alloy steel subjected to a special heat treatment process, maintaining structural flexibility while exhibiting excellent fatigue resistance. The rigid pulley utilizes an internal gear structure precision-cast from carbide, with an optimized tooth profile for optimal meshing with the flexspline. This three-layer nested structure, which achieves power transmission through elastic deformation, enables the harmonic reducer to achieve high reduction ratio motion conversion in a compact space. Its structural rigidity and dynamic response significantly surpass those of traditional gear transmissions.

[0037] The working principle of harmonic reducer is as follows Figure 2As shown in the figure, the deceleration effect of a harmonic reducer stems from the synergistic mechanism of elastic deformation and mechanical meshing. When the wave generator rotates driven by the input shaft, its elliptical profile forces the flexspline to undergo periodic elastic deformation. This controlled deformation causes the meshing area between the flexspline's outer teeth and the rigid wheel's inner teeth to shift regularly with the rotation angle. Due to the precise design of a 2-4 tooth difference between the flexspline and the rigid wheel, the flexspline experiences a cumulative effect of small angular displacement relative to the rigid wheel with each complete rotation. This displacement differential is ultimately converted into a high reduction ratio motion on the output shaft through the leverage of the transmission system. Specifically, as the wave generator rotates, the flexspline ring gear, under the action of the deformation wave, sequentially forms a two-point symmetrical meshing area with the rigid wheel's tooth surface. As the wave generator continues to rotate, the meshing area continuously shifts along the circumferential direction. This dynamic meshing process not only ensures a smooth transition in motion transmission but also absorbs microscopic vibrations during the transmission process through elastic deformation, enabling the harmonic reducer to achieve a reduction ratio of over 100:1 while maintaining micron-level transmission accuracy.

[0038] The relationship between position and speed in the transmission model of the harmonic reducer can be analyzed from its structural characteristics and kinematic principles. Under ideal transmission conditions, the motion relationship between the input shaft and the output shaft of the harmonic reducer is directly determined by the reduction ratio, which is defined as the ratio of the input speed to the output speed and is usually determined by the difference in the number of teeth of the flexspline and the rigid wheel. Let the number of teeth of the flexspline be Z f , the number of teeth of the steel wheel is Z g , then the theoretical reduction ratio i can be expressed as:

[0039]

[0040] This mathematical relationship shows that the position change of the output shaft θ out and the input shaft position change θ m satisfy:

[0041]

[0042] The output speed ω out Then with the input speed ω in In strict proportional relationship, that is:

[0043]

[0044] Taking friction into account, the relationship can be obtained:

[0045] τ w =-i(τ f -τ fm ) (4)

[0046] where τ w is the torque of the wave generator, τ fis the torque at the flexspline end, τ fm is the friction torque.

[0047] In the classical friction model, Coulomb friction is used as the basic model to derive various improved forms, such as Figure 3 Shown: (a) Coulomb friction model, (b) Coulomb-static mixed friction model, (c) Coulomb-viscous mixed friction model, and (d) Stribeck friction model.

[0048] The Coulomb friction model is a basic theoretical model that describes the friction between contact surfaces. Its mathematical expression is:

[0049]

[0050] Where Fc = μ·Fn represents the Coulomb friction amplitude, μ is the kinetic friction coefficient, Fn is the normal load, and v is the relative velocity. The core characteristic of this model is that the friction amplitude is constant during the kinetic friction phase, determined only by the normal load and the friction coefficient, and its direction is always opposite to the velocity. In the static state, the friction force balances the external force, and its maximum value is determined by the static friction coefficient μ. s Determine, satisfy |F ext ∣≤μ s F n However, the Coulomb model does not consider the dynamic transition characteristics of continuously changing speeds, nor can it describe nonlinear phenomena such as the Stribeck effect. Therefore, it has limitations when analyzing complex friction behaviors. This model is suitable for preliminary system analysis with low requirements on friction characteristics or for simplified dynamic modeling of mechanical systems.

[0051] The static friction-kinetic friction switching model further refines the static friction stage of the Coulomb model, and its mathematical expression is:

[0052]

[0053] The model is constructed by differentiating the static friction coefficient μ s Together with the dynamic friction coefficient μ, the model clearly characterizes the resistance maximization characteristic of the static friction phase: when the system is at rest, friction consistently resists the external force until it exceeds the static friction threshold, at which point the system enters the dynamic friction phase. However, the discontinuity in the transition between static and dynamic friction can lead to convergence issues in numerical simulations. This model is suitable for systems requiring accurate analysis of startup transients, such as start-stop control of highly loaded mechanical structures.

[0054] The Coulomb-viscous mixed friction model extends the Coulomb model by introducing a velocity linear term, which is expressed as:

[0055] F friction =μF n ·sign(v)+bv (7)

[0056] Where b is the viscous friction coefficient. This model superimposes a velocity-proportional viscous term on Coulomb friction, reflecting the speed-dependent increase in friction under lubricated conditions. Its characteristic is that Coulomb friction dominates at low speeds, while the viscous friction effect significantly increases at medium and high speeds. This model combines the advantages of simple structure and clear physical meaning, making it widely used in lubricated mechanical systems and motion control scenarios that require a balance between low-speed accuracy and high-speed stability.

[0057] The Stribeck friction model integrates multiple friction mechanisms through an exponential function, and its mathematical description is:

[0058]

[0059] Among them, F s is the static friction amplitude, v s is the characteristic Stribeck velocity, and δ is the fitting exponent. The model is obtained by e -(v / vs)δ The term characterizes the nonlinear attenuation of friction in the low-speed region, that is, when the speed increases from zero to v s When the friction is gradually reduced due to the transition from boundary lubrication to fluid lubrication, the friction force gradually decreases. It combines the coupled characteristics of static friction, Coulomb friction, and viscous friction, and can accurately describe the friction behavior of all working conditions, from static to dynamic. Therefore, it is widely used in low-speed control of precision servo systems such as robot joints and optical turntables to suppress "creeping".

[0060] In actual transmission, the elastic deformation of the flexspline introduces nonlinear factors: when the wave generator drives the flexspline to periodically deform, the meshing between the flexspline and the rigid wheel teeth is not completely rigid, and the elastic deformation causes a transient transmission phase lag. In terms of speed transmission, the hysteresis effect of the flexspline causes the output speed to exhibit high-frequency, slight fluctuations. The amplitude of the fluctuation is proportional to the square of the input speed, and the frequency is consistent with the rotational frequency of the wave generator.

[0061] At a constant speed, the transmission error of the harmonic reducer has angular position correlation. Based on the dual encoder differential measurement method, the present invention installs high-precision position encoders at the motor end of the turntable and the output end of the harmonic reducer. By real-time monitoring the position difference between the two ends, a transmission error observer is constructed, and the position error dynamic compensation is achieved by combining the feedforward compensation control strategy. The control block diagram after adding the position compensation algorithm is shown in the figure below. Figure 4 shown.

[0062] A high-precision magnetic encoder is installed at the end of the permanent magnet synchronous motor shaft, and a high-precision photoelectric encoder is installed at the end of the turntable. These two encoders synchronously collect position data for error compensation calculations. The turntable is driven in a constant ultra-low speed mode in a fixed direction for several rotations, and the angle value θm of the encoder at the motor end and the angle value θout of the encoder at the output end are recorded. The theoretical output position and position error are obtained through real-time calculation:

[0063] Δθ=θ out -θ m (9)

[0064] The Δθ is stored in the error lookup table with the motor end angle θm as the index. The extended Kalman filter is performed on the motor end encoder data to reduce the impact of the encoder accuracy on the error calculation, and the average of multiple-turn data is taken to suppress random noise.

[0065] In real-time control, the error lookup table is queried according to the current motor end angle θm to obtain the corresponding Δθ. The compensation resolution is improved through the linear interpolation algorithm, and the compensation amount is directly superimposed on the feedback channel of the position loop.

[0066] The design diagram of the ultra-low speed and high precision turntable drive control system is as follows: Figure 5a and Figure 5b As shown, the motor control board 4 includes a motor control board 4, a motor stator 5, a harmonic reducer 6, an output encoder PCB mounting bracket 7, a motor encoder 8, a motor rotor assembly 9, a slip ring 10, an output encoder mounting bracket 11, an output encoder 12, and a base 13. The motor control board 4 integrates an STM32F446RE main control chip and a three-phase inverter drive circuit. It controls BSC040N10NS5 MOSFETs via an IRS2011STRPBF driver chip, achieving precise speed regulation of the permanent magnet synchronous motor. The control board also includes a built-in overcurrent protection module that uses an LMV2903 comparator and a BAT54AFILM diode to monitor phase current in real time, with a response time of less than 1μs. The encoder interface connects to an ICMU200 17-bit magnetic encoder via the SPI protocol, enabling high-resolution rotor position detection at the motor end. The turntable's power transmission structure utilizes a harmonic reducer. This provides a 160:1 reduction ratio, enabling ultra-low-speed operation at the motor end. The ICMU200 magnetic encoder is directly installed at the end of the motor shaft. The 17-bit absolute encoder provides a theoretical angular resolution of 0.0027°. The turntable output is equipped with a 26-bit photoelectric encoder to ensure the accuracy of data measurement.

[0067] The core control part of the turntable system is the motor control board at the motor end. As the core part, the motor control board is responsible for motor drive, closed-loop speed control, signal acquisition and protection, etc. The overall design block diagram is shown as follows: Figure 6 shown.

[0068] An ultra-low-speed, high-precision turntable was used to compare the position errors before and after the position compensation method of the present invention was used. The motor was operated at a constant speed so that the motor end rotated ten times in a clockwise direction. The target angle was set to 90°, and the speed limit was 5 revolutions per minute at the motor end. The position error was recorded using a dual encoder, and then the average value was taken to obtain the position error of one cycle, as shown in Figure 2. Figure 7 The experimental conditions are kept consistent, and the position compensation method of the present invention is used for position control, and the experimental results are as follows. Figure 8 shown.

[0069] Compare Figure 7 and Figure 8 The results show that the positioning accuracy of the motor is significantly improved after the position compensation method of the present invention is adopted. The position error after the position compensation is introduced is only about 0.003°, which is about 82% less than the position error of about 0.024° when no position compensation is added.

[0070] Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. A drive control system for an ultra-low speed and high precision turntable, characterized in that: include: Permanent magnet synchronous motor, used to provide power source for the turntable; The motor-side control circuit board is connected to the permanent magnet synchronous motor and is used to control the operation of the motor; The motor-end encoder and its code disk are installed at the end of the permanent magnet synchronous motor's shaft to detect the position information of the motor end; A harmonic reducer is connected to the permanent magnet synchronous motor to transmit torque and achieve deceleration; The output end encoder and its code disk and slip ring are installed at the end of the turntable to detect the position information of the output end.

2. The drive control system according to claim 1, wherein: The motor-end control circuit board integrates the STM32F446RE main control chip and the three-phase inverter drive circuit.

3. The driving control system according to claim 1, characterized in that: The motor end encoder is a magnetic encoder.

4. The driving control system according to claim 1, characterized in that: The output end encoder is a photoelectric encoder.

5. A position compensation method for an ultra-low speed high precision turntable, characterized in that: The following steps are involved: S1 installs high-precision position encoders on the motor end of the turntable and the output end after passing through the harmonic reducer; S2 synchronously collects position data through the encoder and monitors the position difference between the two ends in real time to build a transmission error observer; S3 realizes dynamic compensation of position error based on the error information obtained by the transmission error observer and in combination with a feedforward compensation control strategy.

6. The position compensation method according to claim 5, characterized in that: The high-precision position encoder includes a magnetic grating encoder installed at the end of the motor shaft and a photoelectric encoder assembled at the output end of the turntable.

7. The position compensation method according to claim 5, wherein: The real-time monitoring of the position difference between the two ends to construct the transmission error observer is specifically as follows: driving the turntable to rotate in a fixed direction for several cycles in a constant ultra-low speed mode, and recording the angle value θ of the encoder at the motor end m and the output encoder angle value θ out , the theoretical output position and position error Δθ = θ are obtained through real-time calculation out - (θ m / i), where i is the reduction ratio of the harmonic reducer.

8. The position compensation method according to claim 7, wherein: Set Δθ to the motor end angle θ m To index into the error lookup table, the motor encoder data is subjected to extended Kalman filtering to reduce the impact of encoder accuracy on error calculation, and the multi-turn data is averaged to suppress random noise.

9. The position compensation method according to claim 8, wherein: In real-time control, according to the current motor end angle θ m The corresponding Δθ is obtained by querying the error lookup table, and the compensation resolution is improved through the linear interpolation algorithm. The compensation amount is directly superimposed on the feedback channel of the position loop.

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