Sensor Fusion Based Estimation Technology of Vehicle Velocity in Anti-lock Braking System

The precondition of realizing slip ratio based anti-lock braking system (ABS) is the accurate measurement of vehicle velocity, which can be vital in simplifying the control laws of ABS. This paper describes an accurate measurement technology for estimating the absolute velocity of a vehicle. First, the signal property of wheel speed sensor has been analysed, the measurement circuit has been designed and simulated, and the wheel speed calculation and filter algorithm has been deduced. Second, the principle and application of one kind of acceleration sensor has been investigated. Third, by utilizing the wheel speed signals and vehicle body acceleration signal and considering the tire radius change and the accelerometer offset, the basic tool of sensor fusion approaches, recursive least squares (RLS), is proposed to estimate the realtime vehicle velocity. Finally, the experiments in a test course were carried out to verify the proposed strategy and prove that it can accurately estimate the vehicle velocity. The maximal absolute estimation error between actual vehicle velocity and estimated velocity is less than 0.4 m/s.