A simple nonlinear filter for low-cost ground vehicle localization system

This paper introduces a simple and intuitive nonlinear observer for low-cost ground vehicle localization system, using measurements from an inertial measurement unit, two wheel speed sensors, and a GPS. Taking advantage of the nonholonomic constraints, the design of the observer takes into account imperfections of the embedded sensors measurements, such as slowly time-varying gyroscope biases or some uncertainty on the angle between the vehicle's frame and the road, to estimate the attitude, velocity and position of a ground vehicle. Thanks to a simple nonlinear structure based on the theory of symmetry-preserving observers, the estimator is easy to tune, easy to implement, and well-behaved even at very low speed. Moreover, the proposed filter presents some guaranteed convergence properties when GPS is available. Simulations and experiments in urban area illustrate the good performances of this simple algorithm.