Experimental evaluation of a nonlinear attitude observer based on image and inertial measurements

This paper presents an experimentally tested solution to the problem of estimating the attitude of a rigid body using rate gyros and a pan and tilt camera. An exponential input-to-state stable pan and tilt control law is used to keep the visual features in the image plane. A multi-rate implementation of the nonlinear attitude observer that uses recent results in geometric numeric integration is proposed. Practical aspects, such as the computation of suitable observer feedback gains, are considered. Experimental results obtained with a high accuracy motion rate table demonstrate the high level of performance attained by the proposed solution.