Longitudinal Collision Avoidance Control of Electric Vehicles Based on a New Safety Distance Model and Constrained-Regenerative-Braking-Strength-Continuity Braking Force Distribution Strategy

Abstract

This paper presents a new control scheme for longitudinal collision avoidance (CA) systems to improve the safety of four-in-wheel-motor-driven electric vehicles (FIWMD-EVs). There are two major contributions in the design of longitudinal CA systems. The first contribution is a new safety distance model to make vehicle adapt to different driving roads with an adhesive coefficient between tire and road and to conform to drivers' characteristics with a driving intention parameter. The second contribution is a new braking force distribution strategy based on constrained regenerative braking strength continuity (CRBSC). By optimizing the braking force distribution curve of hydraulic proportional-adjustable valve, the safety-brake range could be linearized to simplify the calculation of braking force distribution on the premise of ensuring braking safety. Furthermore, it is the constraint conditions that could solve the coexistence problem of positive and negative braking forces based on regenerative braking strength continuity (RBSC) to conform to actual requirements. The feasibility, effectiveness, and practicality of the proposed safety distance model and braking force distribution strategy are, respectively, verified by computer simulation experiments. Rapid control prototyping (RCP) and hardware-in-the-loop (HIL) simulation experiments using dSPACE are carried out to demonstrate the effectiveness in the control scheme, simplicity in structure, and flexibility in implementation for the proposed longitudinal CA system.