An adaptive sensor foot for a bipedal and quadrupedal robot

One key benefit of legged robots is their ability to act on the environment by applying forces in a noncontinuous way in innumerous directions and magnitudes within their designed workspace. Most multi-legged robots are equipped with single-point-contact feet for the sake of simplicity in design and control. This paper focuses on a sophisticated lower limb system for a multi-legged robot to demonstrate the advantages of actuated multi-point-contact feet. Indications for these advantages can be found in nature, where the mechanical and sensory interaction of the feet with the substrate enables highly flexible ways of locomotion in animals and helps to optimize traction. Multi-point-contact feet even enable the transition from quadrupedal to bipedal walking, a dexterous behavior of ape-like mammals. To prove the technical plausibility of the planned leg structure, a first prototype including a lower leg, an actuated ankle joint, an attached foot structure, and a set of sensors with their required electronics was developed and integrated. Due to its characteristics, the lower limb - as a subcomponent of a legged robotic system - will extend the robot's knowledge of its internal and the environmental states. The mechanical and electronic design of the foot structure is presented in this paper as the basis for a later development of a biologically inspired control scheme.