Sliding Mode Roll Control of Active Suspension Electric Vehicles

Abstract

Vehicle roll control has been a well studied problem. One of the ubiquitous methods to mitigate vehicle rollover in the automobile industry is via a mechanical anti-roll bar. However with the advent of electric vehicles, rollover mitigation can be pursued using electric actuation. In this work, we study a roll control algorithm using sliding mode control for active suspension vehicles, where the actuation for the roll control signal is generated by electric motors independently at the four corners of the vehicle. This technology precludes the need for any mechanical actuation which is often slower as well as any anti-roll bar to mitigate vehicle rollover situations. We provide an implementation of the proposed algorithm and conduct numerical experiments to validate the functionality and effectiveness. Specifically, we perform Slalom and J-turn maneuvering tests on an active suspension electric vehicle with sliding model roll control and it is shown to mitigate rollover by atleast 50% compared to passive suspension vehicles, while simultaneously maintaining rider comfort.

Figures (11)

• Figure 1: Plot of the roll angle and the roll rate for an active suspension electric vehicle undergoing the slalom test at a constant longitudinal velocity of 30 kph for approximately 13 s. There is more than $90\%$ reduction in the peak roll rate for active suspension roll control in comparison to passive.
• Figure 2: Plot of the roll angle and the roll rate for an active suspension electric vehicle undergoing the slalom test at a constant longitudinal velocity of 35 kph for approximately 13 s. There is a continued $90\%$ reduction in the peak roll rate for active suspension roll control in comparison to passive. All conditions remain the same as for the 30 kph test.
• Figure 3: Plot of the roll angle and the roll rate for an active suspension electric vehicle undergoing the slalom test at a constant longitudinal velocity of 40 kph for approximately 13 s. There is a continued $90\%$ reduction in the peak roll rate for active suspension roll control in comparison to passive. All conditions remain the same as for the 30 kph test.
• Figure 4: A closeup snapshot of the roll angle and roll rate for active suspension based sliding model roll control. We can notice the increase in perturbations (peakiness) as we increase the constant longitudinal speed from 30 kph to 40 kph. However as observed from the plots in \ref{['fig:Slalom_30kph', 'fig:Slalom40kph']} the active roll control is substantially better than passive suspension systems.
• Figure 5: Plot of the roll angle and the roll rate for an active suspension electric vehicle undergoing the slalom test at a constant longitudinal velocity of 40 kph for approximately 10 s. There is a continued $90\%$ reduction in the peak roll rate for active suspension roll control with a preview time of 0.6 seconds compared to 0.4 seconds.

Theorems & Definitions (2)

• Theorem 1
• proof