Terminal Sliding Mode Adaptive Control Research Articles

Enhancing pressure control of low-friction pneumatic actuator with eddy current damper via valve dead-zone compensation

This article addresses the high-performance pressure control of a pneumatic actuator that incorporates an air-bearing piston and an eddy current damper (ECD). After optimizing the pneumatic actuator, achieving precise pressure control relies on maintaining an accurate and stable airflow through the control valve. A terminal sliding mode adaptive control method (TSMAC) is proposed, proficiently integrating considerations for dead zone nonlinearities in the proportional valve and the effects of unmodeled disturbances in the pneumatic actuator. Using the opening area of the proportional valve as the input to the pneumatic system greatly simplifies the control process and reduces the workload required for valve parameter calibration. The Lyapunov-based stability analysis demonstrates that excellent asymptotic output tracking can be achieved with low steady-state error simply by knowing the boundaries of the valve opening area. The control effect of the proposed control strategy is compared with an adaptive backstepping sliding mode control method based on a linearly fitted proportional valve model on an established constant pressure control test bench. Experimental results under various loads and operating conditions illustrate the effectiveness of the proposed approach.

Adaptive non‐singular fast terminal sliding mode based on prescribed performance for robot manipulators

AbstractA fast convergent non‐singular terminal sliding mode adaptive control law based on prescribed performance is formulated to solve the uncertainties and external disturbances of robot manipulators. First, the tracking error of robot manipulators is transformed by using the prescribed performance function, which improves the transient behaviors and steady‐state accuracy of robot manipulators. Then, a novel fast convergent non‐singular terminal sliding mode surface is brought up according to the transformed error, and the control law is derived to meet the stability requirements of robot manipulators. In practice, the upper boundary of the lumped disturbances cannot be accurately obtained. Therefore, an adaptive prescribed performance control (PPC) controller to lumped disturbances is brought up to ensure the stability and finite‐time convergence of robot manipulators. Finally, the system stability of robot manipulators is proved by the Lyapunov theorem. Simulation results and comparative analysis demonstrate the superiority and robustness of the raised strategy.

Nonsingular Terminal Sliding Mode Adaptive Control for Unmanned Aerial Manipulator in Gliding Grasping

Nonsingular Terminal Sliding Mode Adaptive Control for Unmanned Aerial Manipulator in Gliding Grasping

RBFNN based terminal sliding mode adaptive control for electric ground vehicles after tire blowout on expressway

This paper proposes a radial basis function neural network (RBFNN) based terminal sliding mode control scheme for electric ground vehicles subject to tire blowout on expressway in presence of tire nonlinearities, unmodeled dynamics and external disturbances. For enhancing the longitudinal and lateral stability of the vehicle after tire blowout, a saturated velocity planner is firstly constructed for tracking the original motion trajectory, by which the longitudinal velocity and yaw rate saturation constraints can be effectively handled. Afterwards, a terminal sliding mode controller (TSMC) is designed for tracking the planned velocity signals because of its inherent finite time convergence rate and superior steady-state property, by which the adverse dynamic behaviors can be timely suppressed. Further, to strengthen the adaptability and robustness of the control scheme, a RBFNN approximator is developed for identifying the lumped uncertainty, such as tire nonlinearities, unmodeled dynamics and external disturbances, etc., and then compensated into the controller. Lastly, simulations with front-right tire blowout on expressway are performed to validate the effectiveness and efficiency of presented control scheme and methods, and the comprehensive performance of TSMC+RBFNN and TSMC schemes in maintaining original trajectory tracking capacity is evaluated and discussed.

Non‐singular terminal sliding mode adaptive control of permanent magnet synchronous motor based on a disturbance observer

This study proposes a non-singular terminal sliding mode adaptive control strategy based on a disturbance observer for a permanent magnet synchronous motor (PMSM) with multiple disturbances. Firstly, the multiple disturbances of the PMSM can be divided into two types including a load disturbance formulated by an exo-system, modelling error and circuit noise represented by a norm-bounded equivalent disturbance. Secondly, a disturbance observer is applied to estimate the load disturbance and its derivative. A non-singular terminal sliding mode controller based on the disturbance observer and an adaptive controller is designed to reject the modelled disturbance and compensate the norm-bounded disturbance. Then, the stability of the controlled system is proved by the Lyapunov method. Finally, simulation results of a PMSM control system are provided to verify the effectiveness.