Control system for manipulator apparatus

A method for controlling the movement of a movable member comprising the steps of:

• generating command signals representing the desired movement of said member;
• scaling one or more of said generated command signals in accordance with scale factors representing the variation in inertia of said member over the various controlled movements of said members;
• and
• moving said member in accordance with said scaled command signals and said command signals not scaled for variations in inertia.

A control system for a manipulator having an arm movable in a plurality of axes and including control apparatus that provides position error, velocity and acceleration command signals in response to program data and arm position data, said manipulator arm performing a work cycle in accordance with said program data and said position error, velocity and acceleration command signals, said control system comprising:

• means for inertia scaling one or more of said position error and acceleration command signals in accordance with scale factors representing the variation of the inertia of said arm over said work cycle;
• means responsive to said inertia scaled command signals and said command signals not scaled for variations in inertia for generating axes control signals;
• means responsive to said axes control signals for moving said arm in said plurality of axes;
• and
• means for developing feedback signals representing the position and velocity of said arm and the force on said arm in one or more of said plurality of axes, said axes control signal generating means comprising servo loop control means responsive to said feedback signals and said scaled command signals and said command signals not scaled for variations in inertia, said arm moving means comprising an electrically controlled hydraulic valve for one or more of said axes, each of said hydraulic valves having an overlapping center range of valve movement in which the valve does not provide control output characteristics, said servo loop control means further comprising valve threshold offset actuating means for developing an offset actuating signal of appropriate polarity to said valve independent of said respective axis control signal and in response to the respective axis control signal being less than or greater than zero for said axis controlled by said valve.

A control system for a manipulator having an arm movable in a plurality of axes and including control apparatus that provides position error, velocity and acceleration command signals in response to program data and arm position data, said manipulator arm performing a work cycle in accordance with said program data and said position error, velocity and acceleration command signals, said control system comprising:

• means for inertia scaling one or more of said position error and acceleration command signals in accordance with scale factors representing the variation of the inertia of said arm over said work cycle;
• means responsive to said inertia scaled command signals and said command signals not scaled for variations in inertia for generating axes control signals;
• means responsive to said axes control signals for moving said arm in said plurality of axes;
• and
• means for developing feedback signals representing the position and velocity of said arm and the force on said arm in one or more of said plurality of axes, said axes control signal generating means comprising servo loop control means responsive to said feedback signals and said scaled command signals and said command signals not scaled for variations in inertia, said servo loop control means for at least one of said axes further comprising shunt control means responsive to said respective axis velocity command signal and said respective axis position error command signal for providing a shunt signal directly to said arm moving means independent of said respective axis command signal and in addition to said axis control signal for said respective axis, said shunt control means being active to provide said shunt signal whenever said velocity command signal is below a predetermined level, said shunt control means including means for amplifying said position error command signal to provide said shunt signal.

A method for controlling a manipulator arm movable in a plurality of axes comprising the steps of:

• generating acceleration/torque command signals for one or more of said axes in response to stored program data representing a taught work cycle;
• modifying said generated acceleration/torque command signals in one or more of said axes in accordance with the changes in the effective inertia of said manipulator arm in one or more of said axes as the inertia of said manipulator arm varies during said work cycle in one or more of said axes;
• and
• controlling the movement of said manipulator arm in one or more of said axes in accordance with said modified acceleration/torque command signals and dynamic feedback signals representing the inertial mass system of said manipulator arm to provide the desired torque to said manipulator arm in one or more of said axes in accordance with said effective inertia of said manipulator arm throughout said work cycle.

A control system for a manipulator having an arm movable in a plurality of axes, said control system comprising:

• means for generating acceleration/torque command signals for one or more of said axes in response to stored program data representing a taught work cycle;
• means for defining the effective inertia throughout said work cycle of said manipulator arm in one or more of said axes as said arm moves to perform said work cycle;
• means responsive to said inertia defining means and said acceleration/torque command signal generating means for modifying said acceleration/torque command signals in accordance with the changes in effective inertia of said manipulator arm during said work cycle;
• means for providing dynamic feedback signals for one or more of said axes representing the inertial mass system of said manipulator arm;
• and
• servo loop control means responsive to said dynamic feedback signals and said modified acceleration/torque command signals for controlling movement of said manipulator arm in one or more of said axes to provide the desired torque to said manipulator arm in one or moe of said axes in accordance with said effective inertia of said manipulator arm throughout said work cycle.