Design and modeling of an upper limb exoskeleton to assist elbow joint movement using surface emg signals

Abstract

This paper presents a design and model of a powered elbow exoskeleton to assist the movement of elbow joint. This exoskeleton will strengthen the elbow joint by providing a controllable torque in addition to that generated by elbow joint muscles. Therefore, it can be used for healthy people and for physically weak people, such as disabled or elderly people, in performing their daily activities. The proposed design focuses on using EMG signals recorded from biceps and triceps muscles (which are responsible for elbow joint movements) to control the exoskeleton in performing elbow flexion/extension. The EMG signals and elbow flexion angle were recorded from four healthy subjects whilst performing different tasks of elbow flexion/extension. Pre-processing and conditioning of EMG signals were performed by system hardware while MATLAB/Simulink was used for further signal processing and for designing the whole system of arm and exoskeleton. EMG signals from biceps and triceps muscles were used as reference inputs to the model giving the intended motion. In the design, the parameters of the components, such as the DC motor, gear box and conditioning circuits, were taken from available (off the shelf) cheap components to make it easy and cheap to implement the proposed exoskeleton. In addition, all the torques: the forearm and exoskeleton torques and the torque generated by the muscles, were taken into consideration in the design for being as close as possible to the practice. Future work will be to develop a prototype to implement the proposed design.