  This paper develops a planner that plans the action sequences and motion for
a dual-arm robot to lift up and flip heavy plates using crane pulley blocks.
The problem is motivated by the low payload of modern collaborative robots.
Instead of directly manipulating heavy plates that collaborative robots cannot
afford, the paper develops a planner for collaborative robots to operate crane
pulley blocks. The planner assumes a target plate is pre-attached to the crane
hook. It optimizes dual-arm action sequences and plans the robot's dual-arm
motion that pulls the rope of the crane pulley blocks to lift up the plate. The
crane pulley blocks reduce the payload that each robotic arm needs to bear.
When the plate is lifted up to a satisfying pose, the planner plans a pushing
motion for one of the robot arms to tumble over the plate while considering
force and moment constraints. The article presents the technical details of the
planner and several experiments and analysis carried out using a dual-arm robot
made by two Universal Robots UR3 arms. The influence of various parameters and
optimization goals are investigated and compared in depth. The results show
that the proposed planner is flexible and efficient.
