Biologically Inspired Optical-Flow Sensing for Altitude Control of Flapping-Wing Microrobots

We present the design and fabrication of a 33-mg 1-D optical-flow-based altitude sensor and its integration with a 68-mg flapping-wing flying microrobot. For the first time, an on-board sensor is successfully used to measure altitude for feedback control in a flyer of this size. Both the control strategy and the sensing system are biologically inspired. The control strategy relies on amplitude modulation mediated by optical-flow sensing. The research presented here is a key step toward achieving the goal of complete autonomy for at-scale flying robotic insects, since this demonstrates that strategies for controlling flapping-wing microrobots in vertical flight can rely on optical-flow-based on-board sensors. In order to demonstrate the efficacy of the proposed sensing system and suitability of the combined sensing and control strategies, six experimental cases are presented and discussed here.