Semi-Implicit Euler Realization of Time-Delayed Super-Twisting Algorithm with Modified Smith Predictor

Due to the unavoidable various time delays among the controllers, actuators and sensors in mechatronic systems, which are typically caused by establishing stale communications or time-consuming computations, the closed-loop systems with these delay effects exhibit overshooting, oscillations, and degenerated control accuracy. Conventional methods often focus on the stability analysis of control design with a time delay in the continuous time domain and rarely pay close attention to its digital realization in practical systems. This manuscript proposes a novel control strategy based on the super-twisting algorithm (STA) as the second-order sliding mode control (SMC) with the time delay compensated by a modified Smith predictor (MSP). To reduce the numerical chattering, the STA-MSP is discretized and realized by a semi-implicit Euler method, which makes the STA-MSP insensitive to gain overestimation and large iteration periods of closed-loop control. Simulation and experimental results demonstrate that the proposed STA-MSP realization method achieves high performance in terms of control accuracy when there exists a known constant time-delay between the controller and the actuator.