Force-controlled motion of a mobile platform

Robots are usually built using stiff actuators that can provide impressive motion performances. However, they struggle to control the force, they do not handle collisions graciously and are generally bad at interacting significantly with partially unknown or kinematically constrained environments. One solution is to add a force sensor in the closed-loop control of backdrivable actuators [1], but this is limited in terms of stability, safety and robustness [2] [3]. One of the foremost initiatives using this method was undertaken by the German Aerospace Center (DLR) and resulted in three generations of extensively optimized lightweight robotic arms [4] that can physically interact with people. Performances are impressive but robustness is still an issue.