Chassis System Evaluation Using Force and Moment Allocation

Active Chassis Systems

In a conventional vehicle, the driver controls the trajectory of the vehicle by performing functions like steering, acceleration and braking. These actions generate necessary tire traction forces and moments at the tire road interaction to modify the path of the vehicle.

However what if there is a system where these tire traction forces/moments can be controlled independently. Active Chassis Systems use actuators to modify individual tire traction forces which can bring a lot of opportunities as well as challenges.It increases the degree of mobility. If the rear wheels were allowed to steer, parking maneuvers would be enhanced at low speeds. It also helps in better disturbance handling like crash avoidance and post impact when the driver’s control ability is affected. However, there are only 4 tyres in a car and therefore, eventually, extra actuation or control systems will overlap with each other.

A certain Active Chassis System is described here which can distribute the tire forces optimally using active torque vectoring (traction or braking at each wheel)as well as independent four-wheel-steering to make the best use of available friction. It is an ideal chassis which is then used as an evaluation tool for comparing passive chassis systems. For this study, I used Carsim (https://www.carsim.com ) for Vehicle Dynamics Simulation and Matlab for optimization.