Practical model‐free robust estimation and control design for an underwater soft IPMC actuator. Issue 11 (16th June 2020)

• Record Type: Journal Article
• Authors: Khawwaf, Jasim; Zheng, Jinchuan; Wang, Hai; Man, Zhihong
• Is Part Of: IET control theory & applications. Volume 14:Issue 11(2020)
• Page Start: 1508
• Page End: 1515
• Publication Date: 2020-06-16
• Subjects: actuators -- variable structure systems -- motion control -- robot dynamics -- microrobots -- underwater vehicles -- observers -- robust control -- nonlinear control systems -- mobile robots -- control system synthesis; practical model‐free -- underwater soft IPMC actuator -- soft actuators -- ionic polymer metal composite -- new materials -- innovative soft materials -- superior advantages -- bio‐inspired aquatic robotics -- nimble properties -- soft properties -- silent properties -- flexible properties -- lightweight properties -- nonlinearities -- high‐precision tracking -- control design -- internal system morphology -- model‐free control approach -- underwater IPMC actuator -- exact model -- accurate trajectory tracking -- nonlinear extended state observer technique -- estimation error -- tracking robustness -- nonsingular terminal sliding mode controller -- good tracking accuracy -- strong robustness; Control theory -- Periodicals; Automatic control -- Periodicals; 629.8312
• DOI: 10.1049/iet-cta.2019.1147
• Languages: English
• ISSNs: 1751-8644

Abstract

Abstract : In the trend of the recent development of soft actuators, ionic polymer metal composite (IPMC) is considered as one of the new and innovative soft materials. The IPMC is suited to be utilised in medical micro robots and bio‐inspired aquatic robotics. It is distinguished by nimble, soft, silent, flexible and lightweight properties. In fact, for the IPMC actuator, hysteresis and creep non‐linearities are inevitable; and it is a great challenge to handle them and to achieve high‐precision tracking in the control design, especially when the internal system morphology is complex and not fully understood. This study proposes a new model‐free control approach for an underwater IPMC actuator to overcome the lack of its exact model and to achieve accurate trajectory tracking. This approach is synthesised based on a non‐linear extended state observer technique to estimate lumped uncertainties and disturbances. Furthermore, a sliding mode controller is added as an extra input to deal with the estimation error and to assure the tracking robustness. Finally, the proposed control is experimentally verified to show its effectiveness in comparison with a non‐singular terminal sliding mode controller. The experimental results indicate that the proposed controller is capable of delivering good tracking accuracy with strong robustness.