Study on Roller-Walker - Adaptation of characteristics of the propulsion by a leg trajectory -

Roller-walker is a leg-wheel hybrid mobile robot using a passive wheel equipped on the tip of each leg. The passive wheel can be transformed into sole mode by rotating ankle roll joints when roller-walker walks on rough terrain. This paper describes adaptation of characteristics of the propulsion by a leg trajectory in the case of wheeled locomotion. Firstly, the authors demonstrate that Roller-Walker could achieve high-speed propulsion and slope climbing propulsion by simply changing parameters of the leg trajectory on the hardware experiments. Secondly, an asymptotic parameter tuning method is introduced to perform specified velocity on the different surfaces with different friction. The method is evaluated in numerical simulations. The results suggest that the method allows the Roller-Walker to have a function similar to an automatic transmission of a usual car.