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.
Highlights
The dyskinesia of lower-limbs is mainly caused by stroke, spinal cord injury, and brain injury [1]
The combination of a feedforward/feedback (FF) control scheme based on length-pressure hysteresis compensation of pneumatic artificial muscles (PAMs) [27]–[29] and joint space control is adopted to realize the trajectory tracking control of AirGait, which is a parallel lower-limb rehabilitation robot actuated with PAMs
The control of PAM based on hysteresis compensation is becoming a research hotspot for its simple control scheme
Summary
The dyskinesia of lower-limbs is mainly caused by stroke, spinal cord injury, and brain injury [1]. S. Xie et al.: Trajectory Tracking Control of a Robot Actuated With PAMs Based on Hysteresis Compensation. Yeh et al [23] proposed the control of a lower-limb orthosis actuated with PAMs, where a modified Maxwell-slip model is adopted to characterize their nonlinear hysteresis behaviors. This research is dedicated to solving the application of length-pressure hysteresis compensation of PAMs in the trajectory tracking control of a parallel rehabilitation robot. The combination of a feedforward/feedback (FF) control scheme based on length-pressure hysteresis compensation of PAMs [27]–[29] and joint space control is adopted to realize the trajectory tracking control of AirGait, which is a parallel lower-limb rehabilitation robot actuated with PAMs. The rest of this paper is organized as follows.
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