Low-centroid Crawling Motion for Humanoid Robot Based on Whole-body Dynamics and Trajectory Optimization

Humanoid robots show the ability to replace humans for some dangerous tasks in complex environment. There are various motion types for robots moving into the dangerous environment like walking, rolling and crawling. However, the higher centroid brings instability when humanoid robots execute walking motion. Rolling motion may cause damage crash to the robot's mechanical structure. Therefore, a crawling action with low-centroid and less collision force is designed for robots to execute dangerous tasks. Firstly, a mechanical structure is designed for our robot called BHR-FCR. BHR-FCR own 23-Degree of Freedom (DoF) which provides possibility to achieve crawling motion. Then, Newton-Euler iterative recursion and Lagrange method are adopted for dynamics analysis which provides the basis for trajectory planning. Moreover, in the view of energy loss, the whole-body motion trajectory is generated by dynamic model and trajectory optimization with collocation method. The simulation and real-world experiments depict that BHR-FCR robot is able to crawl across lower wall and crawl on the slope which illustrates the stability of BHR-FCR mechanical structure and the effectiveness proposed algorithm.