US Patent: 3,798,430
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| Reduction of Servo Following Errors in Position and Velocity Control Systems of the Iteratively Computing Type
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Patentees:
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| James B. Simon (exact or similar names) - Fond Du Lac, Fond Du Lac County, WI |
| Thomas B. Bullock (exact or similar names) - Fond Du Lac, Fond Du Lac County, WI |
| Manufacturer: |
| Not known to have been produced |
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Patent Dates:
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| Applied: |
Feb. 27, 1973 |
| Granted: |
Mar. 19, 1974 |
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Joel Havens
"Vintage Machinery" entry for Giddings & Lewis Manufacturing Co.
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Description: |
| Abstract:
Methods and apparatus for reducing following errors in the servo drives of positioning and velocity control systems wherein the commanded position is signaled and updated by increments .DELTA.X during each successive equal time periods .DELTA.T, --so as to cause the controlled member movable along any axis X to travel at a velocity V.sub.x = .DELTA.X/.DELTA.T. The commanded position is updated by iterative computations at least once during each period .DELTA.T, and the .DELTA.X increments to be used for such updating are numerically signaled and can be changed as frequently as once during each period .DELTA.T. In order to create a feed forward signal for application to the servo in a sense additive to the position command signal, the digitally signaled number .DELTA.X is converted into a corresponding analog signal. In the preferred arrangement, this conversion is accomplished by a counter which is preset to the number .DELTA.X at regularly recurring instants and arranged to count down whenever the number held in the counter is other than zero. A decoder responsive to a predetermined count, for example zero, not only terminates the counting action until the next presetting but also produces a constant frequency, variable duty cycle square wave having an average or dc. value proportional to the number .DELTA.X and which serves as an accurate feed forward input to the servo. |
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