  This paper presents a double jaw hand for industrial assembly. The hand
comprises two orthogonal parallel grippers with different mechanisms. The inner
gripper is made of a crank-slider mechanism which is compact and able to firmly
hold objects like shafts. The outer gripper is made of a parallelogram that has
large stroke to hold big objects like pulleys. The two grippers are connected
by a prismatic joint along the hand's approaching vector. The hand is able to
hold two objects and perform in-hand manipulation like pull-in (insertion) and
push-out (ejection). This paper presents the detailed design and implementation
of the hand, and demonstrates the advantages by performing experiments on two
sets of peg-in-multi-hole assembly tasks as parts of the World Robot Challenge
(WRC) 2018 using a bimanual robot.
