A very high-speed piezoelectrically actuated clutching device

Abstract Piezoelectric multilayer actuators can rapidly generate very large stall forces. A typical device measuring 18 mm long by 5 mm square will produce an 800 N stall force in less than 100 μs, however the small output movement obtained, typically 15 μm, is almost unusable in medium or low precision machines. Efficient amplification or transformation of such movement, with optimization of the force-displacement product at the output, makes it advantageous to employ piezoelectric multilayer actuators in lower precision, lower cost high-speed machines, such as those involving clutching or gripping. The mechanism described in this paper is one design in a series of monolithically constructed devices designed around flexure hinges. It generates a 30 N stall force, with an unrestrained movement of over 110 μm, derived from a piezoelectric device which only extends by 15 μm. Although the device cannot be considered highly efficient, it transforms the output movement up to a level which can be used directly with components produced to moderate degrees of surface finish. This paper describes a prototype device whose purpose is to rapidly clutch a thin metal strip. This paper details the device and shows performance data including speed of response, electrical clutching energy and mechanical performance. The efficient displacement amplification of piezoelectric devices is seen as a gateway to many differing applications, currently dominated by the solenoid. Many potential applications exist in the field of robot actuation.