Robust Object Grasping using Force Compliant Motion Primitives

Abstract

Abstract-We address the problem of grasping everyday objects that are small relative to an anthropomorphic hand, such as pens, screwdrivers, cellphones, and hammers from their natural poses on a support surface, e.g., a table top. In such conditions, state of the art grasp generation techniques fail to provide robust, achievable solutions due to either ignoring or trying to avoid contact with the support surface. In contrast, we show that contact with support surfaces is critical for grasping small objects. This also conforms with our anecdotal observations of human grasping behaviors. We develop a simple closed-loop hybrid controller that mimics this interactive, contact-rich strategy by a position-force, pre-grasp and landing strategy for finger placement. The approach uses a compliant control of the hand during the grasp and release of objects in order to preserve safety. We conducted extensive grasping experiments on a variety of small objects with similar shape and size. The results demonstrate that our approach is robust to localization uncertainties and applies to many everyday objects.

An integrated system for autonomous robotics manipulation

“…We present three simple, yet effective, manipulation primitives for robust grasping (and releasing) of small objects from support surfaces [4]: (1) Compliant Finger Placement for bringing all fingers safely in contact with the support surface, (2) Compliant Object Grasping for maintaining the contact between the fingertips and the support surface during the finger closure, and (3) Compliant Object Release for releasing and placing the object gently on the support surface using a method similar to step 2. An example of landing and grasping primitives is shown in Fig.7.…”

“…Similarly to our system, both UMan and Dexter use the combination of Barret WAM arms and hands as their manipulators which provide compliance through cable driven joints, requiring active control of compliance using accurate force sensing. Our system implements a number of active force compliant motions towards grasping and manipulation of objects [4]. HERB, developed at the Personal Robotics laboratory at Carnegie Mellon University [5], is a mobile manipulation platform developed for performing manipulation tasks in human environments.…”

Exploitation of Environmental Constraints in Human and Robotic Grasping

“…Recent research leverages environmental constraints in the suggested manner, for example to position the hand relative to the object (Deimel and Brock, 2013), to cage objects (Kazemi et al, 2012;Deimel and Brock, 2013), or to fix an object during planar sliding (Dogar and Srinivasa, 2010;Deimel and Brock, 2013). Furthermore, specialized, simple gripper designs can exploit surface constraints such as floors to reliably pick up a large variety of objects (Xu et al, 2009).…”

“…Kazemi et al (2012) present a similar strategy; while they control hand orientation based on force feedback, we employ visual feedback.…”

Dual execution of optimized contact interaction trajectories

“…In [5] the importance of first establishing and then maintaining contact (sliding) is made explicit for problems such as peg-in-hole. The DARPA ARM challenge [6] has singled out the importance of contact: several teams have published reports emphasizing that deliberate contact with the environment was key to the robust manipulation of a diverse range of objects [7], [8], [9]. Similarly, Deimel et al [10] presented an insightful study on how humans exploit tactile feedback during grasping, especially when their vision is impaired.…”