Gain adaptation for continuous sliding mode control

Abstract

Abstract-In this paper a novel adaptive sliding mode controller design is presented for robust control of nonlinear uncertain systems. A continuous control law to compensate for the uncertainties is first developed that is completely free from chattering. Focusing on the relation between the tried gain value and the resultant sliding variable, a new method for estimating the uncertainty bounds is then derived, leading to an adaptive law for gain-tuning by which the error eventually lies within a user-specified region in a finite time. Unlike other existing approaches, the new adaptive rule only requires the magnitude of the control input in the previous time step, which greatly eases the application of the proposed algorithm to real-world systems. An inverted pendulum system is simulated to demonstrate the accuracy and effectiveness of the proposed control strategy.

Attitude controller design for the aerial trees-pruning robot based on nonsingular fast terminal sliding mode

“…This article uses the following method (i.e. formula (15)) to determine the relationship between the yaw control torque generated by the main rotors and the culvert thrusters…”

“…where g represents the proportional coefficient, which is determined by the maximum yaw control torque U zmax generated by the main rotors and the maximum yaw control torque U dzmax generated by the culvert thrusters in hovering. According to equations (10), (13) to (15), the desired control torque generated by the attitude controller and the desired control force generated by the position controller can be converted into the speed signals of four rotors and two culvert thrusters.…”

“…Sliding mode control makes the state of the system slide on the sliding mode surface and eventually reaches the equilibrium point by changing the internal feedback control structure of the system. 14,15 It has strong robustness to the uncertainty of model parameters, model errors, and external disturbances. However, ordinary sliding mode controllers cannot make the system state error converge to zero in finite time, 16 so some scholars proposed the fast terminal sliding mode (FTSM) controller.…”