A sit-to-stand trainer system in lower limb rehabilitation

As standing up disability is increasing under the trend of population aging of many countries, a new rehabilitation trainer system for training and analyzing human lower limb athletic ability on sit-to-stand is presented in this paper. An impedance control method was introduced to assure patients safely and effectively stand up in their normal posture. In standing up process human segment rotational angles, movement trajectories, ground reaction forces (GRF), center of pressure (COP) and rope tensile forces were measured by sensors, then the moments of ankle, knee and hip joint were calculated. To validate the effectiveness of the trainer system, sit-to-stand training experiments were implemented on four volunteers. Experimental results validate that the system can insure patients complete the stand up process in their comfortable posture, and that the peak joint moments in impedance training were lower than the joint moments by self-support standing. Furthermore, we noted that in impedance training the joint moments fluctuate around the peak values, which means the trainer system could improve athletic ability of the joint effectively. Therefore, the system is suitable for home-training in which patients could control the training process independently and safely, and it can be applied to assess sit-to-stand dynamic parameters and improve the rehabilitation of patients in clinical settings.