Revealing the Mechanical Characteristics via Kinematic Wave Model for Snake-Like Robot Executing Exploration of Lunar Craters

It is extremely difficult to collect deep lunar soil samples during lunar exploration, as the average thickness of lunar soils is very large, and the power of lunar soil sampling systems is inherently limited. In this paper, we propose the use of serpentine robots to explore lunar craters. Our approach is to first design a kinematic wave model that allows the serpentine robot to satisfy all the requirements of lunar exploration. The resistance encountered by each part of the robot during its motions was measured to identify the parts with the greatest influence on each mode of locomotion to maximize its locomotive efficiency. Accordingly, we have designed a serpentine robot system based on the characteristics of snakes and constructed a kinematic model for serpentine robots in lunar crater environments. In addition, we constructed a lunar soil model using a discrete element method-multibody dynamics co-simulation platform, thus optimizing the locomotion strategy of the robot. The EDEM-ADAMS co-simulation platform was used to simulate the motions of the serpentine robot in a lunar crater, which yielded the resistance, speed of motion, and displacement of the robot's modules during its motions. The optimization analysis of the motion and environmental parameters of the serpentine robot included three variables: the inclination of the lunar crater's walls, the crawling angle of the robot, and the amplitude of the robot's kinematic wave. The dependence of the motions of the serpentine robot on these variables was analyzed using maximum and averaged force values. Finally, validation experiments were performed using a serpentine robot model. Thus, we have optimized the locomotion strategy of the serpentine robot for lunar craters.