Autonomous obstacle avoidance control for extraterrestrial regolith sampling manipulator

Due to the inherent uncertainties associated with extraterrestrial bodies′ regolith environments, the implementation of shallow drilling sampling tasks can be easily hindered by potential obstacles. There is few researches addressing the perception of the environment and the adjustment of mechanism posture during the sampling process. To improve the success rate of sampling and ameliorate the resistance of end-effector during operations, a novel autonomous obstacle avoidance control method is proposed for extraterrestrial regolith sampling tasks. A three-degree-of-freedom manipulator is designed, which is capable of assisting drilling with rotational motion for obstacle avoidance, and kinematic analysis is performed. By utilizing a three-dimensional force sensor to acquire the sampler′s force information, the admittance control and rotational motions are combined for obstacle avoidance. To evaluate the feasibility of the method, several sets of simulation experiments and physical experiments are conducted. Experimental results show that the proposed method can effectively assist the sampler in avoiding obstacles, and significantly reduce the resistance encountered by the end effector during sampling, with improvements in the maximum forces experienced in the X, Y, and Z directions reaching 46. 7%, 57. 0%, and 64. 9%, respectively. In addition, the method addresses the deficiencies of conventional compliant methods, which are prone to interference when applied to shallow drilling. © 2023 Science Press. All rights reserved.