SAPPHYR: legs to pull a wheel structure

The aim of this paper is to show the evolution of our legged robot project and present our new testbed architecture. The reasons why we have built a hybrid robot composed of wheels and legs are given and its behavior commented. First, we recall the actuated leg model based on a thermodynamic study according to pneumatic actuators, as well as on the dynamic model for the mechanic part. The nonlinear controller which ensures good tracking at high velocities is presented. Experiments lead to a new trajectory planning. Moreover, the structure suggests important remarks concerning legged robot design especially according to interaction effect between legs during a complete gate cycle. According to these results, we propose a general decentralized architecture with a coordinator level to ensure a good behavior of the platform