Entwicklung eines ku;die;nstlichen Finges mit Shape Memory Aktoren

The performance and the weight of robots depend significantly on the actuators. During the last years it was constantly tried to achieve better output-weight-ratios through new actuation concepts. A lot of possibilities arise from shape memory alloys (SMA) which have considerable advantages compared to conventional actuators, e.g. an excellent output-weight-ratio, a very high work-volume-ratio, a simple set-up and more. The advantages of shape memory alloys become very pronounced as the size of the application decreases. Large mechanisms may find solenoids, motors, and electromagnets more appropriate whereas in applications where such actuators cannot be used, shape memory alloys provide an excellent alternative. There are few actuating mechanisms which produce more useful work per unit volume than shape memory wires. At the institute for Applied Mechanics (Technical University of Munich) an artificial finger has been developed. Besides the aspects given above, shape memory materials allow - inspired by bionics - a muscle-like setup as well and therefore have been used as actuators in this project. Moreover the results may easily adopted for other grippers. The actuation is based on energized shape memory wires exhibiting a very complex material behavior. Depending on load and temperature a number of unusual effects like shape memory or super elasticity may be observed in these metals. These phenomena are due to a martensite-austenite phase transition in the crystal lattice and to martensitic twinning. The material behavior of SMAs has inspired a quickly increasing number of research projects and technical applications in a diversity of fields and is used as a new form of actuation in this project as well.