Error Caused by Kinematic Control in the Dynamic Behavior of Unmanned Ground Vehicles

Kinematic model-based control of vehicles is an often used technique in the presence of a driver. Existing robust low level (speed, steering, brake, suspension etc.) control components are available in cars which can be influenced using the outputs of the kinematic control as reference signals. If problems arise then the driver can modify the internal control based on the visual information of the path and the observed car motion. In case of unmanned ground vehicles (UGVs) this modification is no more evident. In the paper an approach is presented to estimate the errors in real UGV situations where the road-tire contacts generate special sliding effects in the dynamic behavior of the UGV. These effects are considered as disturbances and are involved in both the kinematic and dynamic models. The novelty of the paper is the result that kinematic control based approaches can cause lateral errors in the order of 1m. In the experiments two type of low level dynamic controls were considered: i) a simplified one using the steering angle of kinematic control, and ii) nonlinear input-output linearization. Both can supply the sliding angle information for the kinematic control.