Load carrying capacity of tractor-trailer mobile robots considering the nonlinear optimal control

Tractor-trailer robot is a kind of mobile robots used to carrey heavy loads. So, load carrying capacity of such robots is an appealing subject which has not been considered up to now. In this article, load carrying capacity of the tractor-trailer mobile robots is investigated using the nonlinear optimal control theory. In point-to-point motion of the tractor-trailer robot, an advanced algorithm based on the indirect solution of the nonlinear optimal control is presented to calculate load carrying capacity of the tractor-trailer robot. Formulation of the optimal control is performed by considering the nonlinear dynamic and nonholonomic equations of the robot as constraints of the problem. Then, by presentation of an advanced iterative algorithm, load of the robot is gradually increased and in each step, optimal conditions are considered as a set of coupled nonlinear differential equation and solved. Load carrying capacity of the tractor-trailer robot is calculated at the final step of the algorithm with consideration of saturation of actuators. Then, the simulation of the tractor-trailer point-to-point motion is performed and the load carrying capacity obtained. The results demonstrate the capability of the proposed algorithm to calculate the load carrying capacity of the tractor-trailer robots and can be applicable for various missions.