Interpolated motion control over a serial network

• US 6,757,583 B2
• Filed: 06/27/2002
• Issued: 06/29/2004
• Est. Priority Date: 06/27/2002
• Status: Expired due to Fees

• Current Assignee: Joe Giamona, Larry Koler
• Original Assignee: Joe Giamona, Larry Koler
• Inventors: Koler, Larry, Giamona, Joe
• Primary Examiner(s): Picard, Leo
• Assistant Examiner(s): Lee, Douglas S.
• Application Number:
  US10/186,074
• Publication Number:
  US 20040002778A1
• Time in Patent Office: 733 Days
• Field of Search: 700/186, 700/189, 700/250, 700/252, 318/568.15, 318/571, 318/573, 318/572, 318/599
• US Class Current: 700/189
• CPC Class Codes: G05B 19/4141 characterised by a controller or microprocessor per axis
• CPC Class Codes: G05B 2219/33187 Serial transmission rs232c, rs422, rs485 communication link
• CPC Class Codes: G05B 2219/33219 Drives, servo units, main control on internal net, lan, ethernet, tcp-ip, wireless
• CPC Class Codes: G05B 2219/33337 For each axis a processor, microprocessor
• CPC Class Codes: G05B 2219/34157 Synchronize interpolation of different axis boards, simultaneous start
• CPC Class Codes: G05B 2219/34448 Integrated servo control circuit fixed to housing, remote from cpu
• CPC Class Codes: G05B 2219/50234 Synchronize two spindles, axis, electronic transmission, line shafting

Abstract

The invention provides a system for controlling motion in machine tools, industrial robots, and motion stages over a computer serial port. From a process or listing of coordinate data points which define the path of two (or more) servo axes, a computer outputs serial port data to distributed Control Modules which regulate an analog torque or velocity command signal to control each axes'"'"' servo drive in a manner that implements a precisely interpolated tool path. A digital I/O link is utilized to synchronize the initial serial port data stream and to compensate for the drift of the individual processor clocks within the separate Control Modules, thereby eliminating the need for network determinism and also reducing hardware costs.

Claims

1. A method for using a computer for controlling the interpolated motion of automated machine tools, industrial robots, and other motion control systems having a plurality of axes, over a non deterministic serial network, comprising:

A. inputting into a computer a Master Control Program;

B. specifying coordinate data points which define a path of at least two Motor means axes;

inputting into the computer and Master Control Program the specified coordinate data points;

C. executing the Master Control Program and generating from the Master Control Program a control set point data stream;

outputting from the computer and Master Control Program the control set point data stream to one or a plurality of control modules (5);

D. outputting from the one or a plurality of control modules one or a plurality of motor means control signal means to one or a plurality of motor means.

E. the coordinate data points composed of a stream of position set points or of a stream of velocity set points of any integer number of encoder counts.

F. motor means provided by servo or step motors;

drive means provided by a servo drive (11) or a step motor drive (13);

G. a motor data communication means provided by a motor power cable (14), providing power to the one or a plurality of servo or step motors (16),(19);

H. the motor means control signal means, including, where Motor means is by servo motors (16), a+/−

10 VDC analog torque/velocity signal (10), that controls the voltage/current transmitted by the servo drive to the motor;

where the Motor means is by a step motor (19), the motor means control signal means is a step and direction pulse (9) generated by an internal voltage controlled oscillator (8) coupled to the Control Module (5) analog output which interfaces with the Control Module (5) to the step motor drives (13) which require a step and direction pulse (9) for control of step motors (19);

I. memory or buffer means composed of a Set Point Buffer (101), and memory or buffer control means is by a buffer control (102);

J. outputting the control set point data stream via an RS-485 multi-drop parallel connection (3);

K. each of the one or a plurality of motor means composed of the combination of a drive means, a motor data communication means, a motor, a commutation data line 12, an encoder (15) and an encoder feedback line (17);

L. inputting the encoder feedback line (17) to the Control Module 5;

the one or a plurality of control modules (5) having memory or buffer means and memory or buffer control means.

2. The method of claim 1 further comprising:

A. the Master Control Program having a Master Control Software function;

the control set point data stream sent by the Master Control Software function, where positional values are used, is;

“

1X₁TA_xET₁2 Y₁TA_yET₁”

where;

1=Unique X axis identifier

2=Unique Y axis identifier

X₁=X axis absolute coordinate position (or incremental distance)

Y₁=Y axis absolute coordinate position (or incremental distance)

TA_x=X axis acceleration time

TA_y=Y axis acceleration time

ET₁=total segment motion time for the given point segment

B. where coordinate data points are composed of a stream of position set points, specifying for each position set point a value, expressed in clock ticks, of a specific elapsed time the exact transition of which determines when a trajectory acceleration must be accomplished;

specifying for each position set point a value, expressed in clock ticks, of a specific elapsed time the exact transition of which determines when a set point position must be reached or crossed;

C. memory or buffer means composed of a Set Point Buffer (101), and memory or buffer control means composed of a buffer control (102).

3. The method of claim 1 further comprising:

A. the Master Control Program having a Master Control Software function;

the control set point data stream sent by the Master Control Software function, where velocity based segment values are used, is “

X₁TA_xET₁Y₁TA_yET₁ where

X₁=X axis velocity to be maintained dining motion

Y₁=Y axis velocity to be maintained during motion

TA_x=X axis acceleration time to velocity X₁

TA_y=Y axis acceleration time to velocity Y₁

ET₁=total segment motion time for the given velocity segment

B. where coordinate data points are composed of a stream of velocity set points consisting of any integer number of encoder counts per clock tick units;

specifying from each velocity set point a value expressed in clock ticks of a specific elapsed time the exact transition of which determines where the velocity acceleration must be accomplished;

specifying for each velocity set point a value expressed in clock ticks of a specific elapsed time the exact transition of which determines when the set point velocity must transition to the next velocity set point;

inputting into the computer and Master Control Program the specified velocity data points;

C. memory or buffer means composed of a Set Point Buffer (101), and memory or buffer control means composed of a buffer control (102).

4. An apparatus in accordance with claim 2 wherein the said means for controlling a digital signal transition in a manner which initiates and maintains synchronized interpolated motion across a distributed motion system.

5. An apparatus in accordance with claim 3 wherein the said means for controlling a digital signal transition in a manner which initiates and maintains synchronized interpolated motion across a distributed motion system.

6. An apparatus in accordance with claim 2, wherein information required to process a data stream of set points and to maintain synchronized interpolated motion, is formatted for transmittal over a serial network.

7. An apparatus in accordance with claim 3 wherein information required to process a data stream of set points and to maintain synchronized interpolated motion, is formatted for transmittal over a serial network.

8. An apparatus in accordance of claim 2 wherein a micro processor based control module processes a position set point data stream for synchronized trajectory control of non specialized servo and step motor drives and motors across a distributed motion system.

9. An apparatus in accordance of claim 3 wherein there is there is means for processing a velocity set point data stream into synchronized velocity control of non specialized servo and step motor drives and motors across a distributed motion system in a manner which maintains interpolated motion.

10. An apparatus in accordance of claim 3 wherein a micro processor based control module processes a velocity set point data stream for synchronized velocity control of non specialized servo and step motor drives and motors across a distributed motion system in a manner which maintains interpolated motion.

11. An apparatus in accordance of claim 1 where in a voltage controlled oscillator is coupled in a manner to the analog control signal of the distributed control module that enables step motor drives to be controlled, in place of servo drives.