Motion control of wearable-type walking support system based on the spring-mass model

Many systems and control methods have been proposed as mobility supports for the physically disabled and elderly individuals. In this research, we focus on a wearable-type system that supports the elderly with their walking. Different from typical control methods of wearable-type walking support systems, we propose a simple control method based on the spring-mass model. As a walking aid that does not require additional motions, such as sit-to-stand, this simple system is beneficial for two reasons. First, it reduces the calculation cost of deriving the support joint torque of the user; second, the wearable device hardware can be simply constructed from low-power actuators and springs rather than high-power actuators. In stance phase support mode, our motion control method compensates for a part of the force applied to the upper body as a leg muscle support. During the swing phase, walking is supported by a trajectory-following method using the impedance control as well as the spring-mass model. The proposed methods are applied to a prototype of a wearable-type walking support system, and evaluated in a series of experiments on human subjects.