Tire Normal Force Estimation Based on Integrated Suspension State Measurement

The vertical tire force can be utilized to obtain information on the longitudinal and lateral force of the tire through the tire friction circle. This means that ride safety can be improved by using the longitudinal force that affects the vehicle’s driving performance and the lateral force that allows for stable cornering without slips. In this paper, we propose a vertical tire force estimation method using sensors that can be implemented in the vehicle. First, the issue of the observability of the tire force is investigated, then we introduce a tire force observer that utilizes the acceleration of the sprung and the displacement between the sprung and unsprung mass. In the proposed observer design, the change in the road surface is taken into consideration as a Gaussian random variable. In addition, a 1/5 scaled quarter car model is developed as an experimental apparatus to evaluate the proposed method, and the proposed method is validated through simulation and experiment.