Design and Control of Shape Memory Alloy Actuated Grippers

Design, investigation and control of two novel Shape Memory Alloy (SMA) wire based gripping systems one operated in open mode and another in closing mode is presented in this paper. A unified design is chosen for both the gripping systems. The gripping systems use SMA wire with a counteracting torsion spring to generated two way motion. Models of the gripping systems are experimentally determined from the open loop step response. Pulse width modulation control (PWM) controller is designed to control the tip displacement of gripping finger. These controllers are compiled to track various stationary and variable (dynamic) trajectories to suit applications that can manipulate objects of varied dimensions. Experimental results show that the grippers are able to track the position rapidly and precisely.