US 4,403,281 AGranted

Apparatus for dynamically controlling the tool centerpoint of a robot arm off a predetermined path

AssigneeCincinnati Milacron Industries, Inc.

InventorsJohn G. Holmes, Brian J. Resnick

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Abstract

An apparatus is disclosed for modifying the motion of a tool centerpoint associated with the function element of a robot arm. The motion to be modified is produced during an automatic mode of operation in which the tool centerpoint travels along predetermined paths between programmed points at a programmed velocity. The apparatus is effective to modify the motion during the automatic mode in response to sensed deviations from the predetermined path. Two alternative schemes of modifying the motion are disclosed. A first alternative scheme returns the tool centerpoint to the predetermined path before it reaches the programmed point defining the end of the path. A second alternative scheme produces a new end point offset from the programmed end point and effects motion along offset paths which are translated and rotated from the predetermined paths defined by the programmed points. Both schemes are suitable for effecting modification of motion in response to deviations which are commanded manually by an operator or automatically by equipment monitoring the workpiece processing effected by the function element.

Claims23

Dependent claims

An apparatus for modifying the motion of a tool centerpoint associated with a function element, the motion being along predetermined paths between programmed points and being defined by input signals representing positions and path velocities therebetween relative to a rectangular coordinate system, the apparatus comprising

(a) a robot arm including means associated with the tool centerpoint for providing a plurality of axes of motion to move the tool centerpoint along predetermined paths, the plurality of axes of motion defining a generalized coordinate system and the arm including a plurality of actuators for effecting motion;
(b) means for producing a deviation signal during motion between programmed points to command a change in position of the tool centerpoint off the predetermined paths;
(c) a control including means for storing the input signals and a servomechanism circuit connected to the actuators to move the tool centerpoint along the predetermined paths, the control further including;
(1) means for recalling first input signals representing first and second program points and a path velocity therebetween
(2) means for iteratively producing sets of individual control signals representing generalized coordinate values relative to the generalized coordinate system of points along a path offset from the predetermined path, the means for producing sets of individual control signals further including;
(a) means for producing in response to first input signals, a set of intermediate signals representing intermediate coordinate values relative to the rectangular coordinate axes of an intermediate point located an incremental distance from the first programmed point along the predetermined path,
(b) means for modifying the set of intermediate signals and the recalled program point signals in response to the deviation signal to produce modified intermediate signals and recalled programmed point signals representing offset points displaced from points along the predetermined path, and
(c) means for generating in response to the modified sets of intermediate signals and recalled programmed point signals, a set of individual control signals representing generalized coordinate values relative to the generalized coordinate system of an offset point;
and
(3) means for iteratively applying the sets of individual control signals to the servo mechanism circuit to operate the actuators in a coordinated manner to move the tool centerpoint through offset paths displaced from the predetermined paths.

7 more elements

An apparatus for modifying the motion of a tool centerpoint associated with a function element, the motion being along a predetermined path between two programmed points and being defined by input signals representing positions and a path velocity therebetween relative to a rectangular coordinate system, the apparatus comprising

(a) a robot arm including
(1) a base,
(2) an upper arm having one end in mechanical communication with the base and being movable with respect to the base about two perpendicular axes of rotation
(3) a lower arm having one end associated with the function element and the other end pivotally joined to the other end of the upper arm by a third axis of rotation;
and
(4) a plurality of actuators each indepenently controlling one of the axes of rotation, said axes of rotation and the upper and lower arm defining a generalized coordinate system independent of the rectangular coordinate system;
and
(b) means for producing a deviation signal during motion between programmed points to command a change in position of the tool centerpoint off the predetermined path;
(c) a control including means for storing the input signals and a servomechanism circuit connected to the actuators to move the tool centerpoint along the predetermined path, the control further including;
(1) means for recalling first input signals representing first and second program points and a path velocity therebetween;
(2) means for iteratively producing sets of individual control signals representing generalized coordinate values relative to the generalized coordinate system of points along the predetermined path, the means for producing sets of individual control signals further including;
(a) means for producing in response to the first input signals, a set of intermediate signals representing coordinate values relative to the rectangular coordinate axes of an intermediate point located an incremental displacement from the first programmed point along the predetermined path,
(b) means for modifying the set of intermediate signals in response to the deviation signal to produce a modified set of intermediate signals representing an offset point displaced from the intermediate point, and
(c) means for generating in response to the modified set of intermediate signals a set of individual control signals representing generalized coordinate values relative to the generalized coordinate system of the offset point;
and
(3) means fo iteratively applying the sets of individual control signals to the servo mechanism circuit to operate the actuators in a coordinate manner to move the tool centerpoint through the offset points between the first and second programmed points.

13 more elements

(a) a robot arm including
(1) a base,
(2) an upper arm having one end in mechanical communication with the base and being movable with respect to the base about two perpendicular axes of rotation,
(3) a lower arm having one end associated with the function element and the other end pivotally joined to the other end of the upper arm by a third axis of rotation, and
(4) a plurality of actuators each independently controlling one of the axes of rotation, said axes of rotation and the upper and lower arm defining a generalized coordinate system independent of the rectangular coordinate system;
and
(b) means for producing a deviation signal during motion between programmed points to command a change in position of the tool centerpoint off the predetermined paths,
(c) a control including means for storing the input signals and a servo mechanism circuit connected to the actuators to move the tool centerpoint along the predetermined paths, the control further including;
(1) means for recalling first input signals representing first and second program points and a path velocity therebetween,
(2) means for iteratively producing sets of individual control signals representing generalized coordinate values relative to the generalized coordinate system of points along a path offset from the predetermined path, the means for producing sets of individual control signals further including;
(a) means for producing in response to first input signals, a set of intermediate signals representing intermediate coordinate values relative to the rectangular coordinate axes of an intermediate point located an incremental distance from the first programmed point along the predetermined path;
(b) means for modifying the set of intermediate signals and the recalled programmed point signals in response to the deviation signal to produce modified intermediate signals and recalled programmed point signals representing offset points displaced from points along the predetermined path, and
(c) means for generating in response to the modified sets of intermediate signals and recalled programmed point signals, sets of individual control signals representing generalized coordinate values relative to the generalized coordinate system of offset points;
and
(3) means for iteratively applying the sets of individual control signals to the servo mechanism circuit to operate the actuators in a coordinated manner to move the tool centerpoint through offset paths displaced from the predetermined paths.

12 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/250,908Filed 3 Apr 1981
Granted: 6 Sep 1983
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

G05B 19/42
Electric: recording and playback systems, i.e. in which the program is recorded from a cycle of operations, e.g. the cycle of operations being…
B25J 9/161
Characterised by the control system, structure, architecture: hardware, e.g. neural networks, fuzzy logic, interfaces, processor
B25J 9/1692
Characterised by the tasks executed: calibration of manipulator
G05B 2219/36417
Nc in input of data, input key till input tape: programmed coarse position, fine position by alignment, follow line, path adaptive