CHARACTERIZATION OF AN INCHWORM PROTOTYPE MOTOR

A new driving principle for an active joint intended for, e.g., a micr orobot, has been evaluated. Piezoelectric bimorphs are used as actuato r elements, and quasistatic positioning in combination with an inchwor m type of repetition produces the rotation. The performance of a macro scopic prototype has been investigated and compared with an analytical model and with finite-element analysis. The agreement between the mod el and the prototype is good, and it is believed that the characterist ics of a microsized active joint can be estimated from the analytical model. The difference in size between the prototype and the proposed m icromotor is a factor of 100. A micromotor is expected to have a very high torque-to-volume ratio (3 kN m-2). Its power and speed limits are believed to be sufficient for an operational micromotor. Other charac teristics that make it well suited for microrobotics are: no gliding c ontact causing wear, simple design and locked rotor when the voltage i s turned off. A possible fabrication process, microassembly, is demons trated. A bimorph microelement has been successfully bonded to a suppo rt on a substrate and the expected behaviour has been verified.