Precise Displacement Control of Tap-Water-Driven Muscle Using Adaptive Model Predictive Control with Hysteresis Compensation

The McKibben-type artificial muscle has been applied to several industrial fields because of its many advantages over traditional actuators, including, high flexibility, low weight, and high power density. However, the muscle has strong asymmetric hysteresis characteristics that are dependent on the load applied, and these problems prevent its widespread application. This study presents an approach to model hysteresis characteristics of the muscle using an asymmetric Bouc-Wen model. Subsequently, control strategies based on several model predictive control, including servomechanism and adaptive algorithm, and a combination of these methods, were applied to the proposed model. Experimental results revealed that model predictive control with servomechanism showed robustness in terms of load and small variation for control performance. Furthermore, the adaptive model predictive control with servomechanism improved control performance in the steady-state response by 46% compared with the model predictive control with servomechanism and demonstrated robustness in terms of changes in the reference frequency.