US4772831A — Multiaxis robot control having improved continuou…

Claim 1

Independent Claim 321 words

A 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; feedback control loop means for each joint motor including at least position, velocity and torque control loops operable to control the associated power amplifier; means for generating motor position, velocity and drive current feedback signals for said control loop means for all of the robot axes; control means including microprocessor means for generating position commands for said feedback control loop means in accordance with predefined moves set forth in a robot program; said position command generating means including planning program means having means for generating a time profile including acceleration, slew and deceleration time segments to implement each commanded robot program move; said position command generating means further including trajectory program means for generating interpolated position commands for each of said 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; means for storing a polynomial equation up to at least the third order; said planning program means further including continuous path means for computing coefficients for said polynomial equation to enable said position commands to be generated 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; said trajectory program means further including means for computing from said 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 said feedback loop means.

Claim 2

Dependent Claim 321 words

A 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; feedback control loop means for each joint motor including at least position, velocity and torque control loops operable to control the associated power amplifier; means for generating motor position, velocity and drive current feedback signals for said control loop means for all of the robot axes; control means including microprocessor means for generating position commands for said feedback control loop means in accordance with predefined moves set forth in a robot program; said position command generating means including planning program means having means for generating a time profile including acceleration, slew and deceleration time segments to implement each commanded robot program move; said position command generating means further including trajectory program means for generating interpolated position commands for each of said 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; means for storing a polynomial equation up to at least the third order; said planning program means further including continuous path means for computing coefficients for said polynomial equation to enable said position commands to be generated 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; said trajectory program means further including means for computing from said 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 said feedback loop means.

Claim 3

Dependent Claim 45 words

A robot control as set forth in claim 1 wherein the control is a digital control operative at a predetermined sampling rate and having digital feedback control loop means operating in response to digital feedback signals and digital commands for all of the control loops.

Claim 4

Dependent Claim 55 words

A robot control as set forth in claim 1 wherein said continuous path means includes means responding to Cartesian move requests to compute said polynomial coefficients on the basis of position vectors for tool position and on the basis of rotational velocity vectors for tool orientation with said velocity vectors referenced to a predetermined frame.

Claim 5

Dependent Claim 76 words

A robot control as set forth in claim 2 wherein said control means in each of said feedback control loop means includes: a position/velocity microprocessor control means responding to said position commands and position/velocity feedback to generate torque commands; a torque microprocessor control means responding to said torque commands and motor current feedback to generate voltage commands; and pulse width modulating means responding to said voltage commands to generate control signals for the associated power amplifier.

Claim 6

Dependent Claim 317 words

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; feedback control loop means for each joint motor including at least position, velocity and torque control loops operable to control the associated power amplifier; means for generating motor position, velocity and drive current feedback signals for said control loop means for all of the robot axes; control means including microprocessor means for generating position commands for said feedback control loop means in accordance with predefined moves set forth in a robot program; said position command generating means including planning program means having means for generating a time profile including acceleration, slew and deceleration time segments to implement each commanded robot program move; said position command generating means further including trajectory program means for generating interpolated position commands for each of said 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; means for storing a polynomial equation up to at least the third order; said planning program means further including continuous path means for computing coefficients for said polynomial equation to enable said position commands to be generated 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; said trajectory program means further including means for computing from said 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 said feedback loop means.

Claim 7

Dependent Claim 317 words

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; feedback control loop means for each joint motor including at least position, velocity and torque control loops operable to control the associated power amplifier; means for generating motor position, velocity and drive current feedback signals for said control loop means for all of the robot axes; control means including microprocessor means for generating position commands for said feedback control loop means in accordance with predefined moves set forth in a robot program; said position command generating means including planning program means having means for generating a time profile including acceleration, slew and deceleration time segments to implement each commanded robot program move; said position command generating means further including trajectory program means for generating interpolated position commands for each of said 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; means for storing a polynomial equation up to at least the third order; said planning program means further including continuous path means for computing coefficients for said polynomial equation to enable said position commands to be generated 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; said trajectory program means further including means for computing from said 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 said feedback loop means.

Claim 8

Dependent Claim 44 words

A robot as set forth in claim 5 wherein the control is a digital control operative at a predetermined sampling rate and having digital feedback control loop means operating in response to digital feedback signals and digital commands for all of the control loops.

Claim 9

Dependent Claim 75 words

A robot as set forth in claim 6 wherein said control means in each of said feedback control loop means includes: a position/velocity microprocessor control means responding to said position commands and position/velocity feedback to generate torque commands; a torque microprocessor control means responding to said torque commands and motor current feedback to generate voltage commands; and pulse width modulating means responding to said voltage commands to generate control signals for the associated power amplifier.

Claim 10

Dependent Claim 54 words

A robot as set forth in claim 5 wherein said continuous path means includes means responding to Cartesian move requests to compute said polynomial coefficients on the basis of position vectors for tool position and on the basis of rotational velocity vectors for tool orientation with said velocity vectors referenced to a predetermined frame.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1991-09-20	1992-03-21	1992-09-20	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1995-09-20	1996-03-21	1996-09-20	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1999-09-20	2000-03-21	2000-09-20	$7700.00	Window Closed / Lapsed

Multiaxis robot control having improved continuous path operation

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