A Device for Rapid, Automated Trimming of Insect-Sized Flying Robots

Successful demonstrations of controlled flight in flying insect-sized robots (FIRs) $< $500 mg have all relied on piezo-actuated flapping wings because of unfavorable downward size scaling in motor-driven propellers. In practice, the mechanical complexity of flapping wings typically results in large torque bias variability about pitch and roll axes, leading to rapid rotation in free flight for vehicles that are not properly trimmed. Manual trimming by watching high-speed video is tedious and error-prone. In this letter, we introduce an alternative, a trimming device that uses feedback from motion capture cameras to determine and correct for bias torques. It does so using an automated feedback loop, without the need for any visual feedback from the user, or airborne flights which can damage the robot. We validated the device on two different robot flies. After trimming with our device, the robots both took off approximately vertically in open-loop and were able to hover in free flight under feedback control. Our system, therefore, reduces the time of essential yet time-consuming step in robot fly fabrication, facilitating their eventual mass production and practical application.