Grippers

Robot arms typically have end-effectors which can grasp things. These grippers are troublesome when designing a toolbox for arms as they are part of the robot but typically not a part of the robot which is actively controlled unless picking or placing. Additionally, grippers can not be expressed with DH notation but can be with ETS or URDF notation.

Note, some of this has not been implemented yet

Our solution is to add grippers as an attribute to the robot object. Each robot contains a list of grippers (since a branched robot like the PR2 has two grippers). The Links which form the gripper are stored in the new gripper object so the robot's links only contain robot links. This abstaction also makes it possible to have gripper models where you can attach a Robotiq gripper to a Kionva arm for example.

A gripper object can perform forward kinematics to get the position between its base and it's tool tips, close its fingers with a set acceleration/velocity, or set the finger width to be a specified distance.