Motion estimation using optical flow sensors and rate gyros

Optical flow sensors (OFSs), with characteristics of small size, light weight, low cost, little power consumption, fast response and no radiation, are suitable for miniature aerial vehicles (MAVs) to detect the environment around them. According to our recent works, besides the velocity and the flight height above the ground, many other flight states can also be obtained using optical flow sensors and rate gyros, including attack angle, sideslip angle, MAV's Euler angles and so on. In this paper, a placement scheme of OFSs on a MAV is proposed. After establishing the measurement equations, an Unscented Kalman Filter (UKF) is applied to estimate the flight states of the MAV. Simulation results show that the flight states can be estimated accurately and quickly. The initial error between the true values and the estimations will be distinguished in about 4 seconds. Using the estimations as feedbacks, the autopilot can control the MAV effectively. Optimal placement scheme of OFSs is also discussed.