Dynamic Control of a Manipulator with Passive Joints in an Operational Coordinate Space

The authors have proposed a method of controlling a manipulator with passive joints which have no actuators. In this method, the coupling characteristics of manipulator dynamics are used, and no additional mechanisms are required. In this paper, a method to control the tip position of a manipulator with passive joints in an operational coordinate space is proposed. The equations of motion are described in terms of operational coordinates. The coordinates are separated into controlled coordinates and compensating coordinates. The number of the controlled coordinates is the same as the number of active joints. The accelerations of the controlled coordinates can be arbitrarily adusted by using dynamic coupling of the manipulator. The effectiveness of the method is veriied by experiments using a two-degree-of-freedom manipulator with a passive joint. The experiments show that the controlled coordinates of the position of the manipulator can be controlled precisely by use of the proposed method