Samira Deylaghian, Fordonsteknik och autonoma system

Longitudinal vehicle dynamics play a critical role in ride comfort at low speeds, particularly during frequent start-and-stop manoeuvres in everyday driving. Under such conditions, friction-induced dynamics and abrupt changes in acceleration can lead to significant jerk and passenger discomfort. This thesis investigates low-speed longitudinal dynamics with a focus on friction effects, non-smooth behavior, and near-standstill jerk.

A minimal vehicle model is developed to capture the essential longitudinal dynamics associated with propulsion, braking, and friction. To accurately represent transitions between static and dynamic friction, an event-driven numerical framework based on a state-machine formulation is introduced, enabling reliable simulation of stick–slip behavior and zero-velocity crossings. The non-smooth nature of the system is further analyzed using a Filippov framework, allowing phase-space investigation of motion near switching boundaries and providing insight into stability, trapping regions, and oscillatory behavior.

The modeling approach is supported by experimental measurements from a real vehicle test conducted on an inclined road using high-resolution IMU sensors. Experimental data are used for parameter estimation, torque reconstruction, and state estimation through a Kalman filter, enabling phase-space analysis of the relative motion between the vehicle body and wheel. Taken together, the numerical, analytical, and experimental results provide a coherent description of longitudinal vehicle dynamics at low-speed.