Multiaxis digital robot control having a backup velocity monitor and protection system
AssigneeUnimation, Inc.
InventorsEimei M. Onaga, Richard J. Casler, Jr.
Life of this patent
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Abstract
A digital robot control includes a position/velocity microprocessor control and a torque microprocessor control for each of multiple robot axes. Digital position, velocity and motor current feedback signals are generated from motor sensor signals for use in making microprocessor control calculations. A backup velocity determination is made for each joint motor by the torque microprocessor from the motor current feedback, the motor command terminal voltage and the motor resistance and inductance. The robot is shut down if the difference between the feedback and backup velocity values exceeds a predetermined limit.
Claims10
A digital control for a robot having a plurality of arm joints, said control comprising:
- an electric motor for driving each of the robot arm joints;
- a power amplifier operable to supply drive current to each motor;
- each joint motor having digital feedback control loop means operable at a predetermined sampling rate and including digital position and velocity control loops driving a digital torque control loop in accordance with digital position commands to generate digital motor voltage commands for controlling the associated power amplifier;
- means for sensing the motion of each joint motor and for generating corresponding digital position and primary velocity feedback signals for control calculations in said position and velocity control loops;
- means for generating digital signals representative of the respective joint motor drive currents for control calculations in said torque control loop;
- and
- backup velocity monitoring means independently determining the velocity of each joint motor from the motor current and terminal voltage and the motor inductance and resistance;
- and
- means for comparing said primary and backup velocity signals for each joint motor.
A robot comprising:
- an arm having a plurality of joints;
- an electric motor for driving each of the robot arm joints;
- a power amplifier operable to supply drive current to each motor;
- each joint motor having digital feedback control loop means operable at a predetermined sampling rate and including digital position and velocity control loops driving a digital torque control loop in accordance with digital position commands to generate digital motor voltage commands for controlling the associated power amplifier;
- means for sensing the motion of each joint motor and for generating corresponding digital position and primary velocity feedback signals for control calculations in said position and velocity control loops;
- means for generating digital signals representative of the respective joint motor drive currents for control calculations in said torque control loop;
- and
- backup velocity monitoring means independently determining the velocity of each joint motor from the motor current and terminal voltage and the motor inductance and resistance;
- and
- means for comparing said primary and backup velocity signals for each joint motor.
Dependencies are inferred from the claim text.