A Variable Rolling SLIP Model for a Conceptual Leg Shape to Increase Robustness of Uncertain Velocity on Unknown Terrain

The use of simple control schemes with only a few basic sensors and no feedback allows improved stability when traversing unforeseen rough terrain by applying a single controller. Exploiting multiple controllers simultaneously can further improve robustness but is often mechanically hard to implement, especially when stiffness modulation is a controller. To overcome this limitation, we investigate and simulate a leg shape that applies variable leg stiffness and free-leg length. The leg shape couples the physical parameters with the leg angle of a monopod, while the leg orientation is governed with only a simple control law during the flight phase. We study the usage of an optimal controller coupling and show that it can increase robustness to perturbations in the initial horizontal velocity when traversing unknown rough terrain. This work presents the process of obtaining the optimal coupled parameters and demonstrates its benefits. This work also lays the foundations for a conceptual leg shape to exhibit the controllers physically.