Modellbasierte Entwicklung eines mobilen Scouts für extreme Gelände in der planetaren Exploration

Abstract

Robotic exploration of planetary bodies has historically been dominated by wheeled rovers. These rovers are successful, but due to the danger of getting stuck they have to be operated very carefully. In this work an alternative robotic locomotion concept is examined that has been proven to be successful in traversing rough terrain on earth: the rimless wheel, also known as “whegs”. This approach to robotic locomotion represents a compromise between wheels and legs by using discrete footholds to push the robot forward but still performing full wheel revolutions. The former eliminates the need for a continuous track that conventional wheels have and the latter considerably simplifies the mechanism and its control. These aspects as well as its inherent redundancy (multiple spokes per wheel and multiple wheels per robot) make the rimless wheel particularly suited for planetary exploration. Analytical examinations of the kinematics of rimless wheels and different mechanical models of compliant spokes are conducted. Multi-body simulations are then used to verify the conclusions drawn from analytical considerations about running on a plane, step climbing and movement on general unstructured terrain. Suitable parameters of a wheel for a future scout rover are derived by means of a parameter variation. A single rimless wheel is designed and tested to verify the calculations and simulations. The experiments are conducted on a novel testbed at DLR-SR, the “Terramechanics Robotics Locomotion Laboratory”, and support the assertion that the developed compliant locomotion system has the potential to facilitate movement on rough terrain as well as to increase the efficiency of locomotion on hard and flat surfaces.