Simultaneous active control of dynamic backlash, friction, and misalignment in spur geared power transmission of MEMS by piezoelectric transducers by Dr. Hamid Reza Mirdamadi (Visiting Professor ULB)

In dynamic, mechatronic and robotic systems, a basic mechanical component for transmitting motion, force, and power between motor and load is a chain of gears. This type of transmission system is specifically effective for lightweight, small, but large output torque, for example, flapping wing micro aerial vehicles (FWMAV’s). Most of the times, the performance of these geared mechanisms are interrupted by backlash, friction, misalignment, and time-varying elasticity between mating teeth as well as shafts, all of them, exhibiting highly nonlinear phenomena. These phenomena have adverse effects on the motion and power transmission capability of a geared system. For example, for some moments, backlash may cause no rotation of driven shaft and its connected gear, then no leading-edge and wing motion of FWMAV (zero-output), while the DC motor is rotating the driver shaft and its mounting gear (input available). As another example, sliding friction of mating gear profiles will reduce the input energy conversion from electrical to useful mechanical energy, but converts a part of the input energy to some inaccessible heat and sound energy parts, limiting the battery life, in other words, there is some heat loss. As a third example, angular misalignment between center axes of mating gears may magnify both effects of backlash and friction, as well as interfere in the proper power transmission. There are some anti-backlash gear systems, which can reduce static and dynamic transmission errors due to backlash under some limitations, but they cannot reduce all the above-mentioned effects simultaneously. In addition, their servo-controllers need different routes for actuation and sensing, while piezoelectric transducers will do both jobs simultaneously. Moreover, there is the capability of micro/nano-positioning of piezo-actuators to receive the desired regulation and precision.

Dr. Hamid Reza Mirdamadi

Visiting Professor of Mechatronics and Robotics (ULB)