Real-time motion planning of construction equipment mechanism by dual-resolution heuristic search

Introduction of embedded computer control in construction equipment paves the way for implementation of enhancements to improve overall productivity and competitiveness of machines. One of these features is the capability for automated or autonomous machine operation, requiring robust path planning algorithms. To be truly autonomous, the system should be able to plan all motions on its own. In addition, it has to be able to plan in real-time, which introduces hard constraints on acceptable computation times.;This work presents a memory efficient real-time path/trajectory planning algorithm for the blade linkage mechanism of a motor grader. It enables to execute repetitive blade positioning tasks and to move the blade between any two positions without operator interaction while automatically avoiding collision between the blade and frame or wheel parts during the motion of the blade.;Collision-free blade configurations are obtained in a preprocessing phase utilizing deterministic dual-resolution sampling. Moving obstacles such as front wheels and frame articulation functionality, both used for machine steering, are decoupled for complexity and memory reduction. Solutions to particular path planning problems are computed in real-time by heuristic driven A* path search. To enable path planning on current and future anticipated low-cost embedded computer resources of construction machinery, the search strategy is optimized by designing and tuning the behavior of heuristic functions specifically for this problem space. The performance of the heuristic guided method is evaluated and compared to other non-heuristic and heuristic searches. A novel adaptive closed-loop control approach is proposed enabling multi-axis coordinated motion control of the blade under varying load conditions and transient hydraulic system pressure fluctuations.;The performance of the approach is evaluated, and simulation and experimental results show that path and trajectory planning can be accomplished in real-time on the target application.