A Control Strategy for Unsupported Paraplegic Standing Based on Discrete-Time Sliding Mode Controllers

The aim of this study is to propose a control strategy on the basis of discrete-time sliding mode control, for control of ankle joint in paraplegia using functional electrical stimulation. Agonist-antagonist co-activation is used to control the ankle movement. In order to achieve this goal, first, the human is modeled as an inverted pendulum. Second, the nonlinear relationship between inclination angle and center of pressure is modeled. Finally, two discrete-time sliding mode controllers are used to stabilize the upright posture. The results indicate that the mentioned control approach is an effective way in paraplegia using functional electrical stimulation.