Abstract
This paper focuses on a robust continuous sliding mode control (RCSMC) method for manipulator PMSM trajectory tracking system under time-varying uncertain disturbances. The main objective of this study is to improve the trajectory tracking dynamic response and disturbances rejection ability of the manipulator PMSM, and then the manipulator itself, by using the RCSMC method. The RCSMC method consists of two key parts: a terminal continuous sliding mode controller (TCSMC), and an extended state observer (ESO). The TCSMC has been demonstrated to have remarkable capabilities to reduce the chattering phenomenon caused by high frequency switching function in the conventional sliding mode control law, and reject the strong time-varying uncertain disturbances for PMSM velocity loops. However, the high control gain, which could lead high velocity steady state fluctuations, is needed. Therefore, an extended state observer is introduced to estimate the disturbances. The estimated disturbances are further used by the velocity loop controller as a kind of feed-forward compensation to reduce the gain of the TCSMC method. The stability of the PMSM trajectory tracking system with the RCSMC algorithm is guaranteed by the Lyapunov stability criteria. Simulations have been conducted to verify the performance of the proposed RCSMC algorithm. Finally, the proposed RCSMC algorithm is applied in a practical 6-DOF manipulator, and the experimental results exhibit the extraordinary robustness and capabilities in dynamic position tracking characteristics, velocity response and disturbances rejection.
Highlights
T HE advanced permanent magnet synchronous motor (PMSM) can offer many attractive features, such as high accuracy, large power density and quick response
EXPERIMENTAL RESULTS WITH APPLICATION TO A 6-DOF MANIPULATOR In order to further test the validity and feasibility of the proposed robust continuous sliding mode control (RCSMC) algorithm in real situation, experiment with a 6-DOF manipulator has been carried out
While the master and control subsystem each have dedicated local memories and peripherals, they can share data and events through shared memories and peripherals.The maximum main frequency at which the the ARM master subsystem can run is 100 MHZ, and the maximum main frequency at which the the DSP control subsystem can run is 150 MHZ. These features guarantee the stable operation of the 6 PMSMs velocity loops RCSMC algorithm and the other necessary functions
Summary
T HE advanced permanent magnet synchronous motor (PMSM) can offer many attractive features, such as high accuracy, large power density and quick response. With the advantages of easy and simple implementation, the proportional-integral-derivative (PID) control method is often adopted in practical PMSM trajectory tracking control system [1]–[3]. This method can satisfy the control requirements to a certain extent when the mathematical model is accurate. PMSM systems in practical manipulator system are usually affected by different kinds of time-varying uncertain disturbances, such as external load disturbances, unmodeled plant with high order dynamics, internal friction and parameter uncertainty, etc. Under the influence of these disturbances, it is difficult to achieve ideal performance for PMSM systems by the conventional linear PID control methods.
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