In this paper, a computationally efficient chance-constrained rollover-free motion planning method is presented. Specifically, the method is developed to plan motions for reconfigurable vehicles with the knowledge of a 3-D terrain model that has limited accuracy. The overall motion planning problem is formulated as a nonlinear optimal control problem (NOCP) that employs a constraint in the form of a bound on the probability of rollover under terrain-induced vehicle orientation uncertainty. To increase the computational efficiency of the NOCP with nonlinear chance constraint, a geometric interpretation of the chance constraint is derived based on the characteristics of SO(3), the 3-D rotation group. Monte Carlo simulations are provided to demonstrate the usefulness of the geometric interpretation through comparisons with other methods. Experimental data gathered from driving a mobile robot through real forests are also used to validate the proposed model. Finally, path and trajectory generation results obtained with the proposed planning method for a feller-buncher machine traversing through uncertain 3-D terrain are presented to showcase the method’s overall performance and efficiency.

This paper presents a path planning refinement technique that allows the efficient collision and rollover-free motion planning for mobile manipulator robots working on rough terrain. First, the necessary theoretical background on a mobile manipulator's kinematics and dynamic stability measure is introduced. Then, after the brief introduction of the sampling-based path planning problem, the additional refinement stage and its problem formulation will be introduced. Within the refinement stage, the novel Bézier control point addition method is introduced to allow for fast, collision and rollover-free path smoothing using curvature-continuous parametrized curves. Analytical proofs and simulated comparisons are provided in the paper to show effectiveness. The beneficial effect of the refined path on trajectory planning will also be demonstrated through simulation.

This paper presents a dynamic stability-constrained optimal motion planning algorithm developed for a timber harvesting machine working on rough terrain. First, the kinematics model of the machine, and the Zero Moment Point (ZMP) stability measure is presented. Then, an approach to simplify the model to gain insight and achieve a fast solution of the optimization problem is introduced. The performance and computation time of the motion plan obtained with the simplified model is compared against that obtained with the full kinematics model of the machine with the help of MATLAB simulations. The results demonstrate feasibility of fast motion planning while satisfying the dynamic stability constraint.