-Information about the locomotion performance of known rovers is sparse. A comprehensive evaluation of wheeled passive systems is presented in this work. It is based on a static 2D approach that includes optimization of the wheel torques in order to minimize the required friction which is an important performance metric. The evaluation comprises well known rover concepts and new suspension systems. The performance of the systems is compared and interesting effects of some concepts are discussed in more detail including torques and load distribution. The rovers MER (NASA) and CRAB (EPFL) show good performance which is topped only by the eight wheeled DoubleSpring system.

Abstract-The capability to overcome terrain irregularities or obstacles, named terrainability, is mostly dependant on the suspension mechanism of the rover and its control. For a given wheeled robot, the terrainability can be improved by using a sophisticated control, and is somewhat related to minimizing wheel slip. The proposed control method, named torque control, improves the rover terrainability by taking into account the whole mechanical structure. The rover model is based on the Newton-Euler equations and knowing the complete state of the mechanical structures allows us to compute the force distribution in the structure, and especially between the wheels and the ground. Thus, a set of torques maximizing the traction can be used to drive the rover. The torque control algorithm is presented in this paper, as well as tests showing its impact and improvement in terms of terrainability. Using the CRAB rover platform, we show that the torque control not only increases the climbing performance but also limits odometric errors and reduces the overall power consumption.

-The creation of a rover for a specific task requires designing and selecting the mechanical structure specifically for its mission. This can be done by modelling a chassis and evaluating it with specific criteria, which is the aim of the Performance Optimization Tool presented here. This Software makes it possible to compare and improve existing and new designs in a quick and efficient way. The tool presented in this paper is based on a quasi-static approach including optimization of the friction coefficients to model and evaluate the rover.

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