Characterization and Optimization of a Lower Extremity Exoskeleton Device for Leg Muscle Rehabilitation

Robotics-assisted rehabilitation has been one of the popular research areas in recent years. The increase in the elderly population and sports-related injuries, the high cost of physical therapy, and advances in Mechatronics have been crucial factors driving this research. The objective of this project is to provide supplementary motion in knee extension and flexion for lower extremity rehabilitation. The device incorporates pneumatic muscles that closely recreate human muscle movement and surface electromyography (EMG) sensors to activate motions. Recently, tests were carried out to characterize the unit and compare the performance of the pneumatic muscles against the theoretical values provided by the manufacturer. Results indicate limitations in the range of operation of the device, mainly due to the limited contraction ratio of commercially available fluidic muscles. Overall, the project provided vital insights that may be useful for researchers developing exoskeleton devices for rehabilitation. This paper reports the characterization of the EMG sensors and pneumatic-based fluidic muscles used in the ABJ system. To address the shortcomings of the commercially available fluidic muscle, custom muscles are designed and characterized. The results provide significant insights for a redesign of the device. Based on the characterization data, a redesign is proposed for a future generation of the device.