Control of limb movements by functional neuromuscular stimulation

Summary form only given. Functional neuromuscular stimulation (FNS) provides a means to restore motor functions for spinal cord injury (SCI) and stroke patients. Most FNS clinical systems operate under open-loop control methods, but closed-loop hand grasp systems are now being tested. Closed-loop control is most suitable for motor tasks requiring low speed and high accuracy, such as hand grasp. Open-loop feedforward control is desirable for high speed motor acts such as arm movement and walking. To satisfy the requirements of speed and accuracy, and to account for the biomechanics of FNS task control, a combined open-loop and closed-loop controller structure design, called the perturbation controller, is proposed. In this control system, the patient commands initiate the task by instructing the controller with movement direction, distance and speed. The feedforward controller interprets the instructions and generates the desired movement trajectory, stiffness, and feedforward input to activate muscles.<>