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Comparing with traditional braking systems of automobiles, the brake-by-wire (BBW) system has a faster dynamic response and is more suitable for applications that facilitate regenerative braking. As the two main categories of BBW systems, the well-known electro-hydraulic braking system and electro- mechanical braking system are not compact enough and their fail-safe function has always been a worrying aspect. A new BBW system called integrated braking system (IBS) by employing the hydraulic multiplex method was proposed in recent years. The IBS implements power-assisted braking and active braking by means of just an integrated unit. It can certainly be used for ABS, ASR and ESC systems for building up and reducing brake pressure. Presented in the paper is a new structure of IBS, which is mainly composed of a motor, ball screw, master cylinder and four 2/2-way valves.

This paper develops a control strategy for tractor semi-trailers by active trailer steering, aiming at minimizing the sweep width of the vehicle at low speeds. The metric of sweep width is defined to evaluate the maneuverability of tractor semi-trailers under a circular motion with constant speeds. The active steering angle of the trailer for each given front wheel steering angle of the tractor is determined to minimize the sweep width, based on solution of equilibrium equations of both the tractor and the trailer in the yaw plane at a very low speed such as 5 km/h. The two steering angles of the tractor and the trailer are fitted to form an open-loop active-steering control algorithm. A nonlinear tractor semi-trailer system model is built for co-simulation purpose by using TruckSim and MATLAB/SIMULINK to evaluate the active trailer steering algorithm.

Most tractor-semitrailers are fitted with multi-axle trailers which cannot be actively steered, and such vehicles with an articulated configuration are inclined to exhibit instability such as trailer swing, jack-knifing, and rollover at high speed. Proposed in this paper is an optimal control of the yaw stability of tractor-semitrailers at high speed by applying an active trailer's steering angle. An optimal control algorithm is designed by employing a 3-DOF vehicle model in the yaw plane. The optimal linear quadratic regulator (LQR) approach is used with a cost function including sideslip angles, yaw rates of both tractor and trailer, and trailer's steering angle. The yaw stability at the high speed is also quantified by the dynamic performance measurements of lateral path deviation, hitch angle and rearward amplification (RA). The algorithm is evaluated by co-simulations using TruckSim and Matlab/Simulink softwares.

The ample electrical power supply makes brake-by-wire technology more suitable for application in electric vehicles than in conventional vehicles. The fail-safe performance of a brake-by-wire system is a key factor regarding its application on production vehicles. A new control allocation algorithm for improving the fail-safe performance of an electric vehicle brake system is proposed. The electric vehicle is equipped with a four-wheel independent brake-by-wire and steer-by-wire system. The main objective of the algorithm is to maintain the vehicle braking performance as close to the desired level as possible by reallocating the control inputs to the actuators in cases of partial or full failure of the brake-by-wire system. The control algorithm is developed using a two degrees of freedom vehicle model. A pseudo control vector is calculated by a sliding mode controller to minimize the difference between the desired and actual vehicle motions.

Improving driving safety and freeway capacity is an indispensable research issue for road vehicles, especially for tractor semi-trailers, which on the one hand exhibit unstable motion modes at high speeds due to their articulated configurations and undertake the largest part of freight transportation on freeways. Automatic driving is rated as the ultimate solution of vehicle safety since it can significantly reduce accidents resulting from human driver errors. Proposed in this paper is a gain-scheduled PID controller for automatic path-following of a tractor semi-trailer. The PID controller minimizes the vehicle's predicted lateral deviation and heading error with respect to the desired path at a preview point, and gains of the controller are scheduled with respect to vehicle speed.