Design and Control of a planetary Exploration Scout for extreme Environments based on the rimless Wheel

Abstract

Planetary exploration rovers are present on several celestial bodies of our solar system since the early 1970s. Until today just a fragment of all possible information has been gathered, since these rovers are limited in mobility due to their locomotion concepts and soil conditions. In the past years the number of smaller rover concepts increased as well as their agility and velocity. This work is focused on the design of such a rover prototype at the DLR-Institute of SystemDynamics and Control. It is aimed to build the basis for further research in rimless wheels. Intended purpose of this rover is extraterrestrial application in extreme terrain, based on its high mobility and caving capability. Therefor the system is firstly designed and evaluated by finite-element analysis. Several adjustments are made in order to maintain compatibility to the already manufactured wheels. Optimization results of an existing simulation model are used to design locomotion-vital components. Furthermore existing works, addressing the rimless wheels, are analyzed and requirements on subsystem level are deduced from the system requirements. After complete assembly, the system is further analyzed with main focus on the drive train characteristics. Several experiments are performed with various instruments, including a laser tracker, to analyze elasticity, friction, backlash and transmission. Finally the existing simulation model and control are analyzed and adapted to the real system. It is used to design a new simple, EtherCat-based drive controller.