Contact Stability Control of Stepping Over Partial Footholds Using Plantar Tactile Feedback

This work presents a novel method to keep stable contact and balance while stepping over partial footholds for biped humanoid robots with flat feet. We exploit plantar tactile feedback to detect the geometry of the terrain and reconstruct online the new supporting polygon after landing every step. Plantar tactile feedback detects early contacts to stop the swing foot motion. Then we compute the convex hull of the cluster of contact points detected by distributed normal force sensors over the foot soles. The centroid of the supporting polygon is then used for retargeting the reference ZMP and DCM positions. Finally, the supporting polygon is used to define constraints for ZMP balance feedback control. These methods were implemented in two biped humanoid robots running different walking controllers.