On-off control for low-power servo control in piezoelectric micro-robotics

Autonomous micro-systems require extremely strict power budgeting to provide useful battery lifetime and functionality. To produce bio-inspired terrestrial micro-robots, this power budget must encompass servo control of a set of robotic leg joints. Piezoelectric actuators can provide high-force actuation necessary for such an application, but driving circuitry for piezoelectric actuator control can consume excessive power. On-off control can reduce actuator power consumption by eliminating analog amplification and minimizing the number of on-off transitions required to perform a given leg joint motion, as compared to conventional PWM controllers. A sample on-off controller designed to require a limited number of on-off transitions from a prototype system is described, and trade-offs to motion accuracy and robustness as power consumption is reduced are discussed. Experimental tests are conducted on a macro-scale piezoelectric test-bed.Copyright © 2008 by ASME