Model Analysis and Experimental Study of Lower Limb Rehabilitation Training Device Based on Gravity Balance

Abstract

More hemiplegia patients tend to use equipment for rehabilitation training due to the lack of physical therapists and the low effect of manual training. Nowadays, lower limb rehabilitation training devices for patients in grade 2 of the Medical Research Council (MRC-2) scale are still scarce and have some issues of poor autonomy and cannot relieve the muscle weakness of patients. To address these problems, a prototype based on gravity balance was designed with the combination of springs and linkages to enable patients to passively experience the rehabilitation training in the state of balancing the gravity of lower limbs. The motion of the mechanism was analyzed to obtain the functional relation between the motor rotation angle and the joints’ angle. Based on the principle of constant potential energy, a gravity balance mathematical model of the device was established, analyzed, and simulated. Moreover, through the training experiment, the results show that when subjects in three different weights were trained under the rehabilitation device with and without gravity balance, the required torques of the motor and EMG signal strength of the knee and hip joints decreased by a degree of significance, which verified the effectiveness of the device’s gravity balancing characteristics for MRC-2 patients.

Design and optimization of lower limb exoskeleton based on multi-axis knee joint

“…Olinski et al (2021) designed an adjustable knee joint mechanism for the rehabilitation treatment of the knee joint, which uses a cross-four-bar linkage and can gradually correct the motion of the knee joint according to the driver's needs. Through kinematics and dynamics simulation, Tang et al (2023) proved the effectiveness of the cross-four-bar linkage joint by comparing the single-axis joint, the cross-four-link joint and the exoskeleton with the extra degree of freedom of the lower leg on the basis of the cross four-link joint. A design method of lower-limb exoskeleton (LLE) based on cross four-bar linkage mechanism is introduced in this paper, which optimizes the parameters of lower extremity exoskeleton by capturing human leg motion through a vision system.…”