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The energy requirements of a solar-powered exploration rover constrain the mission duration, traversability, and tractive capability under the given limited usable power. Thus, exploration rover design, more specifically, rover wheel design (related to considerable energy consumption in driving), plays a significant role in the success of exploration missions. This paper describes the modeling of an operational environment and a multi-body dynamics (MBD) simulation tool based on wheel-terrain interaction model to predict the dynamic behavior on a digital elevation model (DEM) map. With these simulation environments, a multidisciplinary optimal wheel design methodology, integrating the MBD simulation tool and non-dominated sorting genetic algorithm-II (NSGA-II), is developed. Design parameters are chosen through sensitivity analysis. These multi-objective optimizations in dynamic states are conducted to obtain the optimal wheel dimension that meet the limited power condition with maximal tractive capability under the given operational environment. Furthermore, numerical and experimental verification using a single wheel testbed on lunar simulant are conducted to convincingly validate the derived optimization results. Finally, these results reveal that the proposed design methodology is an effective approach to deciding the best design parameter among a large variety of candidate design points considering the restricted power requirement.

A wheeled robot operating on various complex terrains with scattered obstacles and steep slopes must be capable of surmounting obstructions and coping with the extreme driving environment. This paper proposes a body rotation mechanism that controls the load distribution on the robot wheel for the robot to surmount rocky obstacles and steadily ascend deformable slopes. This work formulates a robot dynamics model based on the wheel-complex terrain interaction model to analyze the mechanical effect of the proposed body rotation mechanism. Moreover, an optimal body rotation configuration integrating the robot dynamics model and non-dominated sorting genetic algorithm-II is obtained to choose the appropriate body rotation control strategy. The numerical analysis results conclusively prove the effectiveness of the proposed mechanism. The robot with its fabricated platform is field tested by allowing it to surmount a rocky obstacle and ascend a deformable slope. The results indicate that the proposed body rotation mechanism is an effective approach for enhancing the mobility of a wheeled robot in traversing complex terrains.

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