Virtually offloading body mass for rehabilitation: A simulation study

This paper describes a computer simulation based investigation of an active body-weight support (BWS) technology which has a high potential of significantly improving treadmill-based locomotion rehabilitation. Using acceleration feedback and force control strategies, the active BWS system can offload not only partial body weight but also partial body mass (thus the dynamic load) of the patient who is supported by the system. As a result of the reduced mass, the patient can perform training with ease and comfort. Due to the safety requirements, the proposed technology has to be thoroughly investigated through simulation and experiment before a human subject experiment can be safely conducted. The work reported in this paper is such a simulation work. In the simulation the physical human is modeled as a multi-body system with 54 degrees of freedom. The model also predicts physical interaction of the feet with the treadmill using contact dynamics simulation. The simulation results verify that the proposed new active BWS system can dynamically and seamlessly reduce dynamic load of the patient in training.