Harmonic Turntable Dual-Position Loop Control for Stable Precision
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Solution Overview
Problem
Existing control systems for turntables with harmonic speed reduction mechanisms suffer from limited response speed and stability, poor output position precision, and instability due to nonlinearity factors, especially in semi-closed and full-closed loop control systems, which are not effectively addressed by current anti-disturbance controllers.
Innovation Solution
A dual-position loop control method and system that utilizes two position sensors, one on the motor shaft and one on the harmonic speed reducer output end, combined with kinetic equation analysis, to perform closed-loop control and active disturbance rejection, employing interpolation and pre-extrapolation calculations to achieve high-precision position and speed control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a semi-closed loop control system is used with feedback sensor mounted on motor shaft, then speed stationarity is improved, but output position precision deteriorates due to nonlinearity factors
Solution Approach 1:
The control system is segmented into two independent loops: an inner loop controlling the motor shaft position and an outer loop controlling the harmonic output position. Each loop has its own feedback sensor and controller, allowing independent optimization of speed stationarity in the inner loop and position precision in the outer loop, resolving the contradiction between these two requirements
Solution Approach 2:
The patent implements dual-position loop feedback control with feedback sensors at both the motor shaft and harmonic output position. The outer loop directly measures output position to compensate for nonlinearity factors, while the inner loop maintains speed stationarity through motor shaft feedback, thereby achieving both high speed stationarity and high output position precision
2Manufacturing precision
If a full-closed loop control system is used with feedback sensor mounted on harmonic output shaft, then output position precision is improved, but system stability deteriorates due to limited proportional gain range
Solution Approach 1:
The control system is divided into nested inner and outer loops, where the inner loop handles high-gain position control and the outer loop handles lower-gain trajectory control. This segmentation allows the full-closed loop to achieve high position precision while the inner loop maintains system stability through appropriate gain scheduling
Solution Approach 2:
The control system dynamically adjusts the proportional gain based on operating conditions and trajectory requirements. The inner loop uses high proportional gain for precise position control, while the outer loop uses lower gain for stable trajectory tracking, allowing the system to adaptively optimize both precision and stability
3Device complexity
If conventional anti-disturbance controller is used without dual-position loop design, then device complexity is reduced, but response speed and stability deteriorate under external nonlinearity disturbances
Solution Approach 1:
The controller is segmented into modular functional blocks including trajectory generation, dual-position loop controllers, and disturbance observers. This modular segmentation achieves high response speed and stability while keeping the overall structure manageable through standardized interface design
Solution Approach 2:
The system performs preliminary trajectory generation and disturbance estimation before actual control execution. The outer loop pre-calculates reference trajectories considering system nonlinearity, and the disturbance observer estimates external disturbances in advance, enabling faster and more stable response without excessive complexity
Data Source
AI summary
A dual-position loop control method and system of a turntable are based on a harmonic speed reduction mechanism. The system and the method use feedbacks from two positions with the help of a first position sensor mounted on a shaft of a motor and a second position sensor mounted on an output end of a harmonic speed reducer respectively. The response is fast at the position of the shaft of the motor, and the second position sensor at the output end of the harmonic speed reducer can directly measure the position of a harmonic output end. Therefore, the influence of nonlinearity factors on the control system is reduced.