Unimation, Inc.

Staubli International Ag.

Rajan C Penkar

Richard J Casler, Jr

Eimei M Onaga

Leonard C Vercellotti

Richard A Johnson

Kenneth E Daggett

William Perzley

Barrett L Booth

Roy E Lancraft

Timothy P Skewis

Jeffrey R Davis

Chi Sha

A digital control provides adaptive feedforward torque control for a robot having a plurality of arm joints. An electric motor drives each of the robot arm joints and a power amplifier supplies drive current to each motor under controlled operation. Each joint motor has feedback control loop means including position and velocity control loops driving a torque control loop in accordance with position commands to generate motor commands for controlling the associated power amplifier. The motion of said joint motor generates position and velocity feedback signals respectively for combination with the position and velocity commands to generate an error signal as a torque command for each of the torque control loops from the corresponding position and velocity control loops. Load force is sensed at the endmost robot joint. The actual load moment for each robot joint on the basis of the load force and the dynamic/kinematic data moment is computed for each robot joint on the basis of stored dynamic and kinematic data for the robot arm. The data and load moments are combined for each joint and applied as a feedforward torque for combination with the position and velocity errors in generating the torque command for each of the torque control loops. A feedback signal representative of the joint motor drive current is combined with the torque command to generate a torque error signal in each torque control loop.

Robot control system having adaptive feedforward torque control for

A digital robot control employs planning and trajectory programs which generate the trajectory plan and trajectory position commands with the use of an acceleration profile and a deceleration profile selected from at least square wave and sine wave profiles.

Multiaxis robot having improved motion control through variable

A coordinate conversion system is provided for moving the manipulator arm and hand in repsonse to an input command signal of the 3.times.4 matrix type. The manipulator is provided with a fixed offset between two of the secondary wrist axes so that a stronger wrist configuration is provided which can handle heavier payloads.

Coordinate conversion system and method for controlling an industrial

A completely digital robot control operates at a predetermined sampling rate. The robot arm has a plurality of joints with each driven by an electric brushless or brush-type DC motor which is in turn supplied with drive current by a power amplifier bridge circuit having power switches connected therein to supply motor winding current in the forward or reverse direction. Incremental or absolute encoders and tachometers provide for generating digital position and velocity feedback signals generated synchronously with the sampling rate. Digital motor current feedback signals are also generated synchronously with the sampling rate. Paired position/velocity microprocessors generate torque commands for each of the robot axes at the sampling rate in response to the position commands and the position and velocity feedback signals. Paired torque microprocessors generate motor voltage commands for each of the robot axes at the sampling rate in response to the torque commands and the current feedback signals. Pulse width modulators generate digital motor control signals for each of the robot axes at the sampling rate in response to the voltage commands. The digital control signals for each axis are coupled to control terminals of the corresponding power switches to control on/off switch time and satisfy the motor voltage commands and thereby satisfy the position commands.

Digital control for multiaxis robots

A digital robot control is provided with digital position, velocity and torque control looping to operate joint motors associated with multiple axes of the robot. Motion programming includes planning and trajectory programs for generating position commands for the control looping on the basis of acceleration, slew and deceleration values that specify robot program specifications for timed moves.

Multiaxis robot control having capability for executing timed moves

A digital control is provided for a robot having a plurality of arm joints. The control includes an electric motor for driving each of the robot arm joints and a power amplifier supplies drive current to each motor. Each joint motor has feedback control loop means including at least digital position, velocity and torque control loops operable at a predetermined sampling rate to control the associated power amplifier. Digital motor position, velocity and drive current feedback signals are generated for the control loop means for all of the robot axes. Paired system microprocessors or paired position/velocity microprocessors generate position commands for the feedback control loop means in accordance with predefined moves set forth in a robot program. A planning program generates a time profile including acceleration, slew and deceleration time segments for each commanded robot program move. A trajectory program generates position commands for each of the feedback control loop means in accordance with a curved path trajectory and in accordance with the time profile applicable to the current move segment. The trajectory program employs stored third order polynomial equations and arc equations each having predetermined variable parameters operative to particularize that equation to a commanded curved path segment. The trajectory program responds to parameters specified by the robot program and implements the stored equations corresponding to the specified parameters to generate the position commands and define a tool tip trajectory corresponding to the curved path defined by the robot program.

Multiaxis robot control having curve fitted path control

A digital control for a robot having a plurality of arm joints includes an electric motor for driving each of the robot arm joints and a power amplifier operable to supply drive current to each motor. Pulse width modulators generate digital control signals for the power amplifiers. Feedback control loop means for each joint motor includes at least position, velocity and torque control loops operable to control the associated power amplifier. Motor position, velocity and drive current feedback signals are generated for the control loop means for all of the robot axes. A position/velocity microprocessor control executes a planning program to generate a time profile including acceleration, slew and deceleration time segments for implementing each commanded robot program move. It also executes a trajectory program to generate interpolated position commands for each of the feedback control loop means along the present path segment in accordance with a predefined type of path move and in accordance with the time profile applicable to the present path segment. Execution of a continuous path routine in the planning program provides for computation of coefficients for a stored polynomial equation to enable the position commands to be generated in joint and Cartesian moves as tool orientation and tool position commands that produce smoothed robot tool motion both in tool orientation and tool position between the initial transition point at the end of the slew portion of one path segment to the end transition point at the beginning of the slew portion of the next path segment. The trajectory program computes from the polynomial coefficients interpolated position commands that produce smoothed tool positioning and orientation motion between path segments without position, velocity and acceleration discontinuities in the operation of each of the feedback loop means. The position/velocity microprocessor control computes torque commands from the position command and position/velocity feedback for all of the axes. A torque microprocessor control generates voltage commands for the pulse width modulators from the torque commands and motor current feedback for all of the axes.

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Woodbury, CT, United States of America

Rajan C Penkar