Abstract
This paper proposed a braking torque controller via two-time-scale design with a sliding mode for electric vehicles with four in-wheel motors. According to the different changing rates between the vehicle and wheel motion during the braking process, the design of the braking controller is carried out in two steps. In the first step, a nominal braking controller is developed over the slow-time scale without considering the tire-road friction. Then, a tire-road friction observer is adopted in the fast-time scale to recover the performance of the nominal braking controller. Owning to the high nonlinearity and complexity of the braking system, a sliding mode surface is further added in the nominal braking controller to ensure the stability and robustness of the proposed braking controller. A braking supervisor is adopted to enable the proposed braking controller, which is based on the wheel slip as well as vehicle speed condition. And a torque allocation scheme is presented for the coordination between the regenerative braking system and the friction braking system in each wheel. Co-simulation is conducted using MATLAB/Simulink and CarSim. The effectiveness of proposed controller under different braking conditions is fully validated. A delicate controller area network (CAN) bus model is developed via SimEvent, by which the robust performance of proposed braking controller against CAN-induced time-varying delays is also investigated.
Highlights
Braking system is of great importance to the ground vehicles [1], which directly determines the active safety performance
When the vehicle speed is lower than the threshold value, the regenerative braking system is disabled, while the friction brake system outputs its maximum torque to lock the wheels until the vehicle is stopped completely
It can be concluded that proposed braking controller can maintain desired performance in different road conditions, which is robust to external disturbances, modelling errors, and even controller area network (CAN)-induced time-varying delays
Summary
Braking system is of great importance to the ground vehicles [1], which directly determines the active safety performance. There are two methods to calculate the tire-road friction in the braking control. W. Li et al.: Two-Time-Scale Braking Controller Design With Sliding Mode for Electric Vehicles Over CAN is developed as an alternative approach for tire-road friction calculation. Considering the different changing rates between the vehicle and wheel motion during the braking process, time-separately design is an effective method for the braking controller [35]. To further test the robust performance of the proposed controller against CAN-induced delays, a detailed model of a CAN bus was developed in this paper. Μ is the friction coefficient, which related to the slip ratio λ, the road condition μH , the tire temperature T , the vehicle velocity v, and the wheel side slip angle α.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
