A Trajectory Tracking Control of a Robot Actuated With Pneumatic Artificial Muscles Based on Hysteresis Compensation

Abstract

This paper presents a new trajectory tracking control strategy for a novel lower-limb rehabilitant robot, AirGait, which is a parallel mechanism with three degrees of freedom and is actuated with four pneumatic artificial muscles (PAMs). Compared with the existing control methods, the feature of this approach is that it combines the feedforward/feedback (FF) controller based on the length-pressure hysteresis compensation of PAMs with a joint space control method on the trajectory tracking control of a parallel mechanism. For the controller design, the inverse and forward kinematic formulas of AirGait are developed firstly based on the structure analysis. Then, a lower-limb kinematic model of humans is developed and the human-like trajectory of time is obtained by using a Fourier series method. Finally, the control scheme is introduced and the trajectory tracking control of AirGait with two reference input signals is presented. The comparative experimental results indicate that the performance of this control approach is strong and this robot holds great promise for assisting lower-limb locomotion. INDEX TERMS Trajectory tracking control, hysteresis compensation, feedforward/feedback (FF) control, lower-limb rehabilitation robot, pneumatic artificial muscle (PAM), joint space control. SHENGLONG XIE was born in Anqing, China, in 1988. He received the B.S. degree in mechanical design, manufacturing, and automation and the M.S. degree in mechatronic engineering from the

Design and Hierarchical Force-Position Control of Redundant Pneumatic Muscles-Cable-Driven Ankle Rehabilitation Robot

“…To further confirm the HFPC's tracking performance, a comparison is made with relevant studies of the pure position control for PM-driven devices [35][36][37] . Since the movement range and evaluation index in each reference are not exactly the same, they are normalized to the maximum error percentage in total movement range, with the detailed comparison results shown in Table VI.…”

“…The performance of HFPC without subjects (22.07%) is just weaker than the robust iterative feedback tuning (IFT) controller in [35]. Even if HFPC's position control accuracy decreases with a subject's participation, the error of 28.09% is still better than that of [36,37]. For robot-assisted rehabilitation, the safety of patients is the top priority in the training process.…”

Dynamic Modeling and Performance Analysis of a New Redundant Parallel Rehabilitation Robot

“…Fig. 1 illustrates the virtual prototype of our study object, which is the main part of a new parallel rehabilitant robot-AirGait [35]. It contains two bodies (the moving platform and the base), PRR limbs, PSS limbs, and PR limbs (also called restricted limbs).…”

Angle Tracking Robust Learning Control for Pneumatic Artificial Muscle Systems

“…Pneumatic artificial muscle (PAM) systems are a kind of novel tube-like biomimetic actuators. They can contract or extend by inflating and deflating pressurized air through servo valves, which are similar to human skeletal muscles in size and power output capability [2]- [5]. Thanks to no cumbersome mechanisms used, the devices actuated by PAMs have many advantages, such as cheapness, light weight, compliance, high power/weight ratio and high power/volume ratio [6], [7].…”