Design and implementation of a new body weight support (BWS) system

Abstract

Gait training is a critical rehabilitation procedure for patients suffering from walking problems. It, however, puts the therapist in high orthopedic risk since he should prevent the patient from possible falling. Body weight support system is a new technology helping such patients and the involved therapist by unloading a percent of the patient's weight. A new over-ground body weight support is introduced in this article. The system is composed of two main modules namely unloading and traction. The unloading module is capable of suspending an individual's weight up to 1000N dynamically. The whole system is attached to an overhead rail, moving over the head of the patient by the traction subsystem in order to keep the rope as vertical as possible. The performance of both modules is controlled by an error-based closed loop controller and the results are evaluated in different working conditions. This system is able to keep the average root-mean-square of the unloading force error within 10% of its desired amount. It can also maintain the root-mean-square of the rope angle in the range of 4 to 7 degrees by the traction motor, trying to minimize the horizontal force exerted to the individual.