Linearizing the joint torque characteristics of an electric direct-drive robot for high performance control of in-contact operations

Conference · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5828820

Muir, P F

Many robot control algorithms for high performance in-contact operations including hybrid force/position, stiffness control and impedance control approaches require the command of the joint torques. However, most commercially available robots do not provide joint torque command capabilities. The joint command at the user level is typically position or velocity and at the control developer level is voltage current, or pulse-width, and the torque generated is a nonlinear function of the command and joint position. To enable the application of high performance in-contact control algorithms to commercially available robots, and thereby facilitate technology transfer from the robot control research community to commercial applications, a practical methodology has been developed to linearize the torque characteristics of electric motor-amplifier combinations. A four degree-of-freedom Adept 2 robot, having pulse-width modulation amplifiers and both variable reluctance and brushless DC motors, is converted to operate from joint torque commands to demonstrate the methodology. The average percentage torque deviation over the command and position ranges is reduced from as much as 76% to below 5% for the direct-drive joints 1, 2 and 4 and is cut by one half in the remaining ball-screw driven joint 3. 16 refs., 16 figs., 2 tabs.

• Research Organization: Sandia National Labs., Albuquerque, NM (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5828820
• Report Number(s): SAND-91-1669C; CONF-920540--3; ON: DE91018799
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420203* -- Engineering-- Handling Equipment & Procedures
ALGORITHMS
COMPUTERIZED CONTROL SYSTEMS
CONTROL SYSTEMS
DEGREES OF FREEDOM
ELECTRIC MOTORS
EQUIPMENT
FEEDBACK
JOINTS
LABORATORY EQUIPMENT
MANIPULATORS
MATERIALS HANDLING EQUIPMENT
MATHEMATICAL LOGIC
MOTORS
ON-LINE CONTROL SYSTEMS
ON-LINE SYSTEMS
REMOTE HANDLING EQUIPMENT
ROBOTS
TORQUE