In this paper, we consider cooperative multiple manipulators with passive joints and study the effect of a combination of active and passive joints. This kind of manipulator system may restrict the direction of the end-effector's force depending on which joints are set to passive ones. In the case of operating and transferring a common object, this restriction may give a less effective force and excessive internal force to the object. To use driving force effectively, the question of which joints are set to passive ones must be considered. Therefore, we show the effect of the joint configurations by case studies.

This paper proposes an algorithm to determine suboptimal paths and trajectories for cooperative multiple manipulators with passive joints. The problem of operating and transferring the object from a given start point to a given goal point is considered. In this case, in general, degrees of freedom of the manipulators are larger than that of the object, and thus this manipulator system involves redundancy. Several joints can be changed to passive ones. We use remaining redundant degrees of freedom to refine trajectories. We apply this algorithm to a two-manipulators system. Simulation results show the effectiveness of the algorithm.

A motion planning problem of a cooperative multiple manipulator system carrying out grinding work or similar works to the object is considered. One manipulator holds the object rigidly and the other holds the tool and works on the object's surface. At the contact point between the object and the tool there exists friction, so that interaction forces must be taken into consideration in the dynamics of manipulators and the object. We only specify the tool task on the object's surface, so the object and manipulators can move arbitrary paths in the world coordinates frame. We propose an algorithm to generate joint trajectories for cooperative multiple manipulators to accomplish the specified task effectively.

This paper proposes a method of planning collision free joints paths for two cooperative manipulators. When two manipulators hold a common object and execute specified tasks, there are problems related to handling and collision. To move two manipulators effectively, all of them must be considered together. There are redundancy aspects peculiar to the cooperative two manipulators. We use this redundancy and the potential function method to avoid collisions between the object and the link, the link and the link, the link and the obstacle and so on. Simulation results show the effectiveness of the proposed method.