This paper examines using electric vehicles with independently actuated wheels and anti-squat/lift/dive suspensions to improve passenger comfort by reducing the lift, pitch, and roll motion of the vehicle chassis. Anti-squat/lift/dive suspensions use an angled suspension bar to transfer a portion of the longitudinal driving force into a vertical reaction force on the chassis. Using this effect, we derive a control-oriented model of the lift, pitch, and roll of the chassis where the steering angle and the four driving forces of the individual wheels are the control inputs, and the road-height is a disturbance. Notably, the derived model considers acceleration and cornering explicitly, and thus the coupling between the driving forces and the steering angle. Besides, the influence of the time-varying road height is also included in the derived model. The model is simplified under the assumption that the suspension deflections are small during normal, comfortable driving. We showed, through controllability analysis and open-loop simulations, that the state of the sprung-mass can indeed be influenced by the controlled driving forces. Finally, we use steady-state analysis and open-loop simulations to provide intuition about the relationship between the driving forces and the motion of the chassis. The effectiveness of the control-oriented model was demonstrated by comparison with the original model in the open-loop simulations. 


Improving Passenger Comfort by Exploiting Hub Motors in Electric Vehicles: Suspension Modeling

Division / Sponsors: 
Dynamic Systems & Control (DSCD)

Paper Proceedings: https://asmedigitalcollection.asme.org/DSCC/DSCC2020/volume/84270

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