Interpolated motion control over a serial network
OwnerJoe Giamona, Larry Kolerinventors
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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.
Claims11
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.
Dependencies are inferred from the claim text.