Manipulator and control method
United States Patent No.4,928,047
[Inventors]
Hirohiko Arai, Susumu Tachi
[Applicant]
Agency of Industrial Science & Technology, Ministry of International Trade, Tokyo, Japan
[Issued/Filed Dates]
May. 22, 1990 / March 20, 1989
[Application Number]
US1989000325926
[IPC Class]
B25J 001/02;
[Priority Number]
JP1988000080079
[Abstract]
A multiple-degree-of-freedom manipulator having a plurality of joints is improved by providing some of said plurality of joints being provided with holding brakes, and providing any remaining joints with actuators which generate angular acceleration or linear acceleration in the joints provided with holding brakes while the holding brakes of the joints are released. A method of controlling the multiple-degree-of-freedom manipulators provided with one or more joints provided with holding brakes and one or more joints provided with actuators, comprises the steps of controlling the angular displacement or linear displacement of joints which have no actuators by the torque or force of joints which have actuators by means of the dynamic coupling between joints while the holding brakes are released, and controlling the angular displacement or linear displacement of joints which have actuators by means of the actuators while the brakes are engaged.
[Claims]
What is claimed is:
1. A multiple-degree-of-freedom manipulator comprising:
- a plurality of links;
- at least one passive joint for joining adjacent links and which is provided with a first sensor for detecting relative angles or relative displacements of said links and a brake which is brought to an operating state wherein said passive joint is completely fixed immovably and a release state wherein said passive joint is freely movable;
- at least one active joint for adjacent links and provided with an actuator for actuating said active joint and a second sensor for detecting relative angles or relative displacements of said links; and
- control means for driving said actuator and switching said brake between said operating state and said release state on the basis of relative angles or relative displacements of said links detected by said first and second sensors.
2. A method for controlling a multiple-degree-of-freedom manipulator having a plurality of links joined together with at least one passive joint provided with a brake and a first sensor and at least one active joint provided with an actuator and a second sensor, comprising the steps of:
- detecting relative angles or relative displacements of said links with said first and second sensors;
- giving a desired value to said active joint when said brake is in an operating state wherein said passive joint is completely fixed immovably and, on the basis of the difference between said desired value and a signal detected by said second sensor, driving said actuator to accelerate or decelerate said active joint;
- giving a desired value to said passive joint when said brake is in a release state wherein said passive joint is freely movable and, on the basis of the difference between said desired value and a signal detected by said first sensor and signals detected by said first and second sensors, driving said actuator to accelerate or decelerate said passive joint; and
- controlling said passive joint to be brought to said operating and release states and, at the same time, driving said actuator, thereby accelerating or decelerating said passive or active joint to position said manipulator at a position corresponding to a desired value.