Terramechanics-based Analysis and Control for Lunar/Planetary Exploration Robots

Surface mobility using wheeled mobile robots (Rovers) is one of the important technologies for lunar/planetary exploration missions. The rover in these missions significantly expands the exploration area and thus increases the scientific or programmatic return from the mission. These planetary exploration rovers are expected to travel long distances and perform complex tasks in order to fulfill challenging mission goals. Surface terrain of the Moon or a planet such as Mars is covered with fine-grained soil called regolith, or boulders, rocks, or stones spread over the terrain. Because of the challenging terrain, the rover should be aware of mobility hazards, such as, vehicle tip-over, and collision with obstacles. In particular, the wheel of the rover will easily slip on loose soil, and then, the wheel might get stuck. Subsequently, following an arbitrary path on loose soil becomes a difficult task for the rover because of the slip. In addition, planning an appropriate path on rough/loose terrain to avoid the mobility hazards turns out a complicated issue since the slippage dynamically depends on the posture/velocity of vehicle, soil characteristics, and wheel-soil interactions. Comprehensive studies to tackle these drawbacks are quite necessary for the development and reliable operation of the rover. This research, therefore, addresses mainly three issues: 1) development of an analytical model for investigations of the motion behavior of the rover on loose soil, 2) path following control with considering the slip-compensated approach, and 3) path planning and performance evaluation method to obtain the safest path in order to tackle the slip dynamic problem in the path planning issue. For the issue of the development of an analytical model for motion behavior, this research deals with two models. First, a wheel-soil contact model are developed based on Terramechanics approach in order to address the wheel slip/skid motion. Subsequently, the motion behavior of the rover is numerically obtained by using a wheel-and-vehicle