# An Investigation on the Effect of Lateral Motion on Normal Forces Acting on Each Tires for Nonholonomic Electric Vehicle: Experimental Results Validation

Conference paper
Part of the Lecture Notes in Mechanical Engineering book series (LNME)

## Abstract

Electric vehicles are gaining popularity among people since it is environmentally friendly and carves a path for a better autonomous vehicle. Furthermore, EVs with in-wheel motors tend to provide better torque control since the current for each motor can be defined precisely. The torque of each wheel is controlled to ensure effective traction to ensure vehicle stability. The traction of the wheels is closely related to the vehicle mass. The previous study shows that lateral motion exerts more normal force on the inner wheels of the vehicle. An experimental study is done using a small scale EV fitted with accelerometers to detect the acceleration experienced at each tire. The longitudinal and lateral acceleration is used with the load transfer equation to estimate the normal force exerted at each tire. The results show that increasing vehicle velocity at the same road curvature induces more load transfer towards the inner tire. Furthermore, the experimental results show that the simulation model is accurate and valid.

## Keywords

Normal force Vehicle stability Nonlinear vehicle model

## Nomenclature

$$\ddot{x}$$

longitudinal acceleration of the vehicle (m/s2)

$$m$$

total mass of the vehicle (kg)

$$F_{xij}$$

longitudinal force at each tire, where i = front, rear and j = left, right (N)

$$F_{yij}$$

lateral force at each tire, where i = front, rear and j = left, right (N)

$$\delta$$

steering angle of the wheel (rad)

$$\ddot{\varphi }$$

$$\ddot{y}$$

lateral acceleration (m/s2)

$$I_{z}$$

Inertia moment of the vehicle

$$l_{w}$$

distance between rear wheels (m)

$$l_{f}$$

distance from front wheel to the centre of gravity of the vehicle (m)

$$l_{r}$$

distance from rear wheel to the centre of gravity of the vehicle (m)

$$l$$

Sum of $$l_{f}$$ and $$l_{r}$$

$$g$$

gravity (m/s2)

$$h_{g}$$

height of the centre of gravity of the vehicle (m)

$$N_{zij}$$

normal force at each tire, where i = front, rear and j = left, right (N)

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