Problem formulation for path tracking automation of low speed articulated vehicles

The paper concerns the problem of path tracking control in the class of vehicles made up of two units with an articulation between the two. Each unit has two fixed (nonsteerable) wheels. Steering action is, thus, performed by changing the angle between the front and rear units. Such a vehicle is used for transfer of ore inside the relatively narrow and restricted underground mine galleries. The articulation in the middle helps also for better capability in curve negotiation. In operation, this vehicle usually moves with a low speed because of the environment. As a result, a number of issues, such as dynamic stability and aerodynamic forces which are important to road vehicles, do not come into effect. Furthermore, as far as the path tracking automation is concerned, the dynamics of the vehicle and tire deformation have little effect and can be neglected. Analysis and formulation of the path tracking problem, thus, can be based on the kinematics only. In this paper the control problem is formulated and verified. The synthesis of a feedback system to govern the steering action, then, becomes possible.