Brake by Wire System for Construction Vehicles

This thesis investigates and proposes a brake-by-wire system for wheel based construction vehicles. The brake-by-wire system consists of an actuator controller that controls the brake valve, a manually controlled electrical brake pedal and a closedloop retardation controller. The brake-by-wire system was proof of concept tested on a Volvo L220F wheel loader. In addition to this, an anti-lock brake system is proposed together with an extended Kalman filter that estimates the vehicle velocity, wheel slip and surface friction coefficient based on wheel speed and acceleration. From simulations it was shown that wheel lock is not very probable except in poor surface conditions. A brief risk analysis and safety assessment was conducted on the brake system according to ISO-26262 to identify the possible hazardous event that the brake system might cause. During the proof of concept test it was shown that the system indeed is working, even though more evaluation and tuning is needed to improve performance.