Towards Sensor Autonomy in Sub-Gram Flying Insect Robots: A Lightweight and Power-Efficient Avionics System

Abstract

Control autonomy in sub-gram flying insect robots (FIRs) introduces challenges arising from their small size such as high-speed dynamics, limited power and payload capacity. Previous work has produced and characterized sensors with compatible mass and power specifications, many of which are biologically-inspired. And controlled flight has been demonstrated using feedback from external motion capture cameras. But to date, no avionics system has been reported that is light enough and capable of providing the feedback necessary to perform controlled hovering flight using only components carried on-board. Here we present such a system. It consists a sensor package consisting of an inertial measurement unit, a laser rangefinder and an optical flow sensor, and an associated estimator based on the nonlinear Extended Kalman Filter (EKF). The sensor suite weighs 187 mg and consumes 21 mW. We implemented a low-latency wireless link to transmit this data at 1 kHz without cumbersome wires. The EKF estimates attitude, altitude and lateral velocities. We estimate that computation power usage is <400 μW using floating-point operations on a standard microcontroller. Our system’s RMSE attitude and position error are less than 4°and 1 cm relative to motion capture estimates.