Modeling, Controlling, and Characterizing the Velo Gripper Prototype

 

During his summer internship, Jeff Hawke from Georgia Tech worked with us on modeling, controlling and characterizing a novel robotic gripper.

The new gripper, named Velo 2G, is underactuated, using a single active flexor tendon to perform both fingertip and enveloping grasps.  To integrate the Velo with the PR2 robot, the first task was to create a Universal Robot Description File (or URDF) containing an analytical model of its actuation mechanism.  The second step was to write a controller able to command the gripper to a desired finger gap, while limiting the applied grip force to a specified value.  Jeff also studied the relationship between applied motor torque and resulting grip force, and wrote a more advanced controller able to sustain large grip forces for prolonged periods of time while applying low current to the actuator.

We are now testing the Velo 2G on the PR2 robot, performing grasping and manipulation tasks on a wide range of objects, both autonomously and under tele-operation. For more details, see the Velo 2G webpage at www.willowgarage.com/velo2g