Coordinate Estimation Scheme for Differential Mobile Robots Using Rotary Encoder

Real-time coordinate estimation for a mobile robot is a crucial task for its control. In this paper we propose three coordinate estimation schemes for differential mobile robots using a pair of rotary encoders. Rotary encoders installed on the differential axis. Firstly, we recover the yaw angle and absolute velocities for each wheels. Then, calculate the velocity vectors for each wheels and integrate them to estimate coordinates. The schemes is numerically simulated on Matlab. For this we construct smooth trajectories for each wheel using Bezier polynomials. We calculate Bezier time instances that divides the curve into equal segments. This is done by solving first-order nonlinear ODE of Bezier time with respect to the natural parameter of the curves. We run our scheme on these time instances and evaluate its estimation error. The coordinate estimation schemes are implemented and experimented on a ARM computer.