Functional Electrical Stimulation Control System Based on MODBUS TCP and OPC Network Protocol

Functional electrical stimulation has been widely used for motor rehabilitation of individuals. In general, applications consist of open and isolated control system operations, i.e., an operator performs stimulator adjustment, without feedback of the behavior of the stimulated limb’s physical variables and without making the process information available to other involved users. An aggravating factor in the electronic systems adopted is that the device signals are interconnected through direct connection, usually analog voltage signals, which are susceptible to attenuation and distortion by noise and interference. In this work, an improvement of electrical stimulation systems through the insertion of a MODBUS TCP industrial communication protocol between sensors, actuators, controller and human-machine interface is proposed. In addition, the controller tuning via OPC protocol for Nexto Xpress XP325 is presented. Results demonstrate the feasibility of this proposal for stimulation system applications with the guarantee of robustness in the communication between the devices, even in hospital or external environments subject to noise and electromagnetic interference.