Intelligent Myoelectric Prosthetic Hand Control System

Artificial hand with myoelectrical control is a new type of dynamic artificial hand and the model "man-machine system" which is controlled by biological electricity. Its principle is to utilize the change of EMG degree from the muscle of stump to be regarded as control signals, to control the movement of artificial hand, to replace the arm that people lost on the body. Compared with other control ways, it has a lot of superiority. By this reason, it is favored by patient and has wide markets, and now it has became a focus in studying of artificial limbs.With the development of the rehabilitation engineering, machinery and electronics, the research of artificial hand is deepened gradually and towards more intelligent development. Traditional artificial hand adopts open-loop control .The greatest disadvantage is lack feedback of feel, so grasps the object with the constant speed and force all the time. Because the control system is relative simple, it is only suitable for the rigidity object. But to the easy distorted object (e.g. film workpiece and soft material, etc.) and fragile object (e.g. egg and glass, etc.) it may cause broken, distorted, damaged on the surface. In addition, if the external force acts on the grasped object suddenly, it is possible to slide. The technology of intelligent artificial limb is a kind of method by which it can simulate the feelings and intelligent behaviors of people by engineering method. Utilizing the sensor to obtain the outside information, it can become closed-loop control. The key technology lies in the sensor and control system. A sensory control system for the artificial hand is presented after analyzing the human grasp process and artificial sense. This system is a mixed sensory feedback loop. The automatic grasp artificial reflex and the state of the artificial hand reflex are its function. Using the touch and slip sensors in the front of finger, the artificial hand can identify the state of grasped object at any moment. An intelligent controlling system with fuzzy control is proposed and tested; the artificial hand can adjust the grip according to the slippage at any time and can obtain a stable grasp.Some experiments about the control system have been done and demonstrate that this control scheme is feasible. It imitates hands very well, responds faster and holds things steady, reliably, but the control system of myoelectrical controlled artificial hand with tactile and slip is a novel thing, so it need the continuous hard work of scholars and engineers.