Fail-safe control allocation for a distributed brake-by-wire system considering the driver’s behaviour

Abstract

A distributed brake-by-wire system provides flexible and precise braking force control with shorter or no brake pipes. Fail-safe control is a critical part of the system which guarantees braking safety during failure of the brake actuators. The purpose of this paper is to develop a fail-safe control strategy that cooperates better with the driver so as to enhance the fail-safe control performance. Therefore, the driver’s behaviour should be taken into account during the design of fail-safe control strategies. Two design goals considering the driver’s behaviour are proposed. The first concerns the braking performance; the second concerns whether the driver can handle the failure situation easily. A qualified fail-safe control strategy should meet both the design goals. The driver model used includes an anti-wind-up proportional–integral controller braking operation model and an optimal preview control steering operation model. Two different fail-safe control strategies, namely strategy I and strategy II, are proposed and examined with the design goals. Strategy I is designed to follow the nominal motions of the vehicle in all the three degrees of freedom in the yaw plane. The pseudo-control vector is determined by sliding-mode controllers and allocated to follow the nominal motions. Strategy II is designed to minimize the braking force imbalance between the left side and the right side of the vehicle on the premise that the brake deceleration demand has been achieved. Simulation results show that strategy I generates a longer braking distance and requires a harder brake pedal force, which violates both the design goals. Strategy II meets both the design goals and therefore is a qualified strategy to cooperate with the driver model. Its capability to be implemented in real time is verified on a hardware-in-the-loop test bench. Its advantages considering the unmodelled behaviour of the driver is also discussed. The distributed electrohydraulic braking system developed is used as the distributed brake-by-wire system.

Quantitative characterization of the reliability of simplex buses and stars to compare their benefits in fieldbuses

“…Intrinsic redundancy can be exploited in domains such as x-by-wire and robotics. For example, the laws that control the operation of a car brake-by-wire system, multicopters and autonomous underwater/remotelyoperated vehicles can be dynamically adapted to respectively tolerate the failure of brake actuators, rotors and thrusters [37,38,39].…”

“…One possibility is to use a simplex topology, replicate just the most critical nodes and, then, use a backup strategy either to provide graceful degradation or to ensure that the system fails in a safe manner. Specifically, it is possible to use an emergency hydraulic/mechanical backup [33,42,37] or to rely on the partial compensation provided by other electronic control subsystems [37,42]. Another option is to take advantage from the natural redundancy/symmetry of the system and, hence, connect half of the nodes to one simplex network and the other half to another simplex one e.g.…”

“…Specifically, consider a typical BBW [41] composed of a Central Brake Management (CBM) ECU, a Brake Pedal Sensor (BPS) ECU and four Wheel Brake (WB) ECUs. Since brake control algorithms can intrinsically compensate the loss of at least one WB ECU [37], imagine that the BBW is able to do so. In addition, to increase the BBW reliability let us assume that the CBM, the BPS and the power supply are duplicated.…”

Review on the Development, Control Method and Application Prospect of Brake-by-Wire Actuator

“…Generally, there are three ways to improve the reliability and security of BBW. The first way is to improve the inherent reliability and reduce the failure probability by using reliability theory and reliability design methods [79]; the second way is to enable the BBW system have sufficient braking capability in the case of partial failure by using fault tolerant technology [48,80,81]; and, the third way is to detect and diagnose the fault in real time, and to remind the driver to repair the fault in time by fault diagnosis technology [77,82].…”

An application of the brain limbic system–based control to the electromechanical brake system

“…By the observation of equations (13) and (14), it is noted that the amygdala gain is not affected when EC is zero; however, the OFC gains rapidly increases and inhibits the output. Once DG A and DG OC are obtained, the output signal of the amygdala (A) and that of OFC (OC) are calculated as noted in equations (11) and (12). As shown in equations (13) and (14), SI and EC perform significant roles in BLS controller.…”