I. Introduction
Traditional serial manipulators are widely used in various grasping operations [1]. If the robot arm is used to complete some grasping tasks, the typical way is to equip the end of the robot arm with gripper [2] –[4], dexterous hand [5] –[7], or soft gripper [8] –[10]. However, this method can only be used to grasp some light and small objects. If it is used to grasp some large objects, the robot arm will be very bulky and huge. Truss structure is widely used in buildings and other structures because of its high stiffness-mass ratio [11]–[12]. If the truss structure is applied to the design of the manipulator, it can greatly reduce the weight of the robotic arm while maintaining the rigidity of the manipulator. In addition, deployment ability is also important for the design of the large manipulator. If the manipulator is too large, the transportation and storage of the manipulator will be very inconvenient. Deployment ability allows it to accommodate a small space when it’s not in use.