Limits to compliance and the role of tactile sensing in grasping

Grasping and manipulation in unstructured environments must handle a wide range of object properties and significant sensing errors. Underactuation and compliance have been shown to be an effective way to improve grasping performance under such uncertainty, but the degree of compliance plays an important role in both gently adapting to sensing errors and maintaining stable grasps of heavy objects. These demands limit the range of objects that can be grasped. We consider the role and required characteristics of tactile sensing as a compensation method when compliance alone is insufficient. By strategic use of contact sensing, it is possible to expand the capabilities of a hand to grasp effectively under a wide range of positioning errors using simple position-driven motors and low-cost hardware.