US 4,623,971 AGranted

Machine control with motor velocity constraint

AssigneeCincinnati Milacron Inc.

InventorsLaVerne K. Ailman, Danny E. Riggen, Ronald L. Tarvin

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Abstract

A method and apparatus are provided for controlling interpolated linear motion of a tool centerpoint associated with a function element carried by a machine. The motion is defined by input signals representing locations relative to an input coordinate system and path velocities therebetween. The machine includes at least one member rotating about an axis which is subject to movement at a velocity greater than the path velocity. Control is effected by producing projected velocity signals for the machine axes for each interpolative iteration and reducing the iterative path velocity in response to detecting a projected axis velocity in excess of an associated axis velocity limit. The control is applicable to machines incorporating a structure in which members must instantaneously change position to maintain the tool centerpoint on the path.

Claims12

Dependent claims

A method for controlling motion of a function element carried by a machine having a plurality of movable members including at least one member pivoting about an axis of rotation and actuators for effecting motion of the members, the motion of the fuction element being described by a continuous path of a point associated with the function element between two locations and being produced in response to input signals representing coordinate values relative to a rectangular coordinate system of the locations and further input signals repersenting a path velocity of said point between said locations, the method comprising the steps of:

(a) producing an increment velocity signal in response to the input signals, the increment velocity signal representing the velocity of the point along the path during a time interval of predetermined duration;
(b) producing a set of machine axes command signals in response to the increment velocity signal, the machine axes command signals representing increments of motion of machine members relative to their respective axes of motion during the time interval;
(c) producing projected velocity signals in response to the machine axes command signals, the projected velocity signals representing velocities of the machine members relative to their respective axes in a time interval subsequent to the interval during which the projected velocity signals are produced;
(d) comparing the projected velocity signals to limit signals, each limit signal representing a limit value of velocity of a machine axis;
(e) iterating steps (a) through (d) to effect a series of increment motions of the point along the path between the locations;
and
(f) reducing the increment velocity signal for an iteration subsequent to an iteration in which a projected velocity signal is detected to exceed a limit signal.

4 more elements

An apparatus for controlling motion of a function element carried by a machine having a plurality of movable members including at least one member pivoting about an axis of rotation and actuators for effecting motion of the members, the motion being described by a continuous path of a point associated with the function element between two locations and being produced in response to input signals representing the coordinate values of the locations relative to a program coordinate system and further inputs signals representing a path velocity of said point between said locations, the apparatus comprising:

(a) means for iteratively producing increment velocity signals in response to the input signals, each increment velocity signal representing the velocity of the point along the path during an iteration interval;
(b) means for producing machine axes command signals in response to the increment velocity signals, the machine axis command signals representing increments of motion of machine members relative to their respective axes of motion for each iteration;
(c) means for producing projected velocity signals in response to the machine axes command signals, the projected velocity signals representing velocities of machine members relative to their respective axes which will occur in an iteration subsequent to an iteration in which the projected velocity signals are produced;
(d) means for comparing the projected velocity signals to limit signals, each limit signal representing a limit velocity value of a machine axis;
and
(e) means for reducing the increment velocity signal for an iteration succeeding an iteration in which a projected velocity signal is detected to exceed a limit signal.

3 more elements

Dependencies are inferred from the claim text.