Digital high-resolution controller

• US 7,466,100 B2
• Filed: 01/17/2005
• Issued: 12/16/2008
• Est. Priority Date: 01/21/2004
• Status: Active Grant

• Current Assignee: Peaktronics, Inc.
• Original Assignee: Peaktronics, Inc.
• Inventors: Leason, Jack M., Mueller, Peter W.
• Primary Examiner(s): Duda; Rina I
• Application Number:
  US11/037,427
• Publication Number:
  US 20050156545A1
• Time in Patent Office: 1,429 Days
• Field of Search: 318/599, 318/811, 318/432, 318/434, 318/471
• US Class Current: 318/599
• CPC Class Codes: G05B 19/291 the positional error is used to control continuously the servomotor according to its magnitude
• CPC Class Codes: G05B 2219/42115 Switch from continuous drive to pwm, near stop or out of acceleration period
• CPC Class Codes: H02P 1/44 by phase-splitting with a capacitor
• CPC Class Codes: H02P 3/18 for stopping or slowing an ac motor
• CPC Class Codes: Y10S 388/934 Thermal condition

Abstract

Kinematic control of an electronic positioner and its associated actuator is effected through a control algorithm that delivers energy to the actuator based on observed motion produced by a previous delivery of energy. The algorithm achieves control based on a desired or user-specified resolution. Electronic braking between energy delivery intervals improves the speed at which the desired position is achieved. Temperature of the force producing mechanism is determined, as by monitoring energy consumed, and used to control how power is delivered to the actuator.

Claims

1. An electronic positioning system for an actuator, comprising:

an actuator operator configured to produce a change in position in an actuator from an initial position to a desired position;

a sensor to ascertain the instantaneous position of the actuator at points intermediate the initial and desired positions;

a controller that determines and progressively applies calculated discrete quantities of electrical energy to said actuator operator to induce successive changes in actuator position and thereby progressively move the actuator from the initial position to the desired position;

wherein the controller determines the quantities of electrical energy progressively applied, based on measured changes in instantaneous position of the actuator at points intermediate the initial and desired positions produced by prior applications of electrical energy to said actuator operator.

2. The electronic positioning system of claim 1 further comprising a braking system that impedes motion of said actuator prior to said application of electrical energy.

3. The electronic positioning system of claim 1 further comprising an electronic braking system that applies alternating energy in at least one of first and second directions.

4. The electronic positioning system of claim 1 wherein said controller determines an inertial compensation value according to coast of the actuator.

5. The electronic positioning system of claim 4 wherein said controller causes a braking sequence based at least in part on the inertial compensation value.

6. The electronic positioning system of claim 4 wherein said controller causes a braking sequence based at least in part on the inertial compensation value and on a desired position of the actuator.

7. The electronic positioning system of claim 1 wherein said controller applies a pulse of electrical energy with a duty cycle that is determined according to changes in position sensed from at least one previous application of electrical energy.

8. The electronic positioning system of claim 1 wherein said controller applies a pulse of electrical energy with a duty cycle and frequency that is determined according to changes in position sensed from at least one previous application of electrical energy.

9. The electronic positioning system of claim 8 wherein the controller determines a rate of change in frequency of applied pulses according to changes in position sensed from at least one previous application of electrical energy.

10. The electronic positioning system of claim 1 wherein said controller applies energy at a rate that is inversely proportional to the temperature of a force producing device that produces said induced changes in position.

11. The electronic positioning system of claim 10 wherein said controller determines temperature according to the amount of electrical energy applied over a given period of time.

12. The electronic positioning system of claim 1 wherein said controller includes analog to digital converter that provides a first faster and lower resolution conversion for motions above a predetermined size and a second slower and higher resolution conversion for motions below a predetermined size.

13. The electronic positioning system of claim 1 wherein said controller is configured to reject electrical noise in said second resolution conversion according to the number of consecutive conversions having a given differential value from an average value of previous conversion values.

14. The electronic positioning system of claim 1 wherein said controller is configured to inhibit application of energy to the actuator according to a lack of motion over a given period of time.

15. The electronic positioning system of claim 1 wherein said controller is configured to determine an association between a desired direction and energy applied to a given direction.

16. The electronic positioning system of claim 1 wherein the actuator operator is configured to produce changes in position in first and second directions and the controller applies energy to the appropriate direction according to a desired direction.

17. The electronic positioning system of claim 14 wherein the controller is configured to reengage energy to the actuator when motion of the actuator is detected after a stall condition.

18. An electronic positioning system for an actuator, comprising:

an actuator operator configured to produce a change in position in an actuator in at least a first direction;

a sensor to ascertain the position of the actuator;

a controller that variably applies a measured quantity of electrical energy to said actuator operator to induce a change in position in said at least a first direction, wherein said variable application of said measured quantity of electrical energy is determined by change in position sensed from at least one previous application of said measured quantity of electrical energy;

wherein said controller is configured to automatically produce a desired output signal that is proportional to the difference of any two selected positions, where such proportionality remains the same regardless of the difference between the selected positions.

19. A method of controlling a actuator comprising:

supplying a first measured quantity of energy to said actuator to produce change in position;

observing the change in position produced thereby; and

supplying a second quantity of energy to said actuator,

wherein the second measured quantity is determined based on the change in position observed and

further comprising controlling the time interval between supplying said first and second quantities of energy such that said time interval is a first value when the assessed distance is within a first proximity range and a second value when the assessed distance is within a second proximity range.

20. The method of claim 19 further comprising controlling the time interval between supplying said first and second quantities of energy based on assessed distance from said desired position.

21. The method of claim 19 wherein said second proximity range is closer to said desired position than said first proximity range and said second value is greater than said first value.

22. The method of claim 19 further comprising engaging a braking system after supplying said first quantity of energy to inhibit movement prior to supplying said second quantity of energy.

23. The method of claim 19 wherein said at least one of said first quantity of energy and said second quantity of energy is supplied as a measured quantity of energy.

24. The method of claim 19 wherein said at least one of said first quantity of energy and said second quantity of energy is supplied as a measured quantity of energy pulses.

25. An electronic positioning system for an actuator, comprising:

an actuator operator configured to produce motion in an actuator in at least a first direction;

a sensor to ascertain the position of the actuator;

a controller that variably applies electrical energy to said actuator operator to induce motion to be produced in said at least a first direction, wherein said variable application of electrical energy is determined by motion sensed from at least one previous application of electrical energy;

wherein said controller includes analog to digital converter that provides a first faster and lower resolution conversion for motions above a predetermined size and a second slower and higher resolution conversion for motions below a predetermined size.

26. An electronic positioning system for an actuator, comprising:

an actuator operator configured to produce motion in an actuator in at least a first direction;

a sensor to ascertain the position of the actuator;

a controller that variably applies electrical energy to said actuator operator to induce motion to be produced in said at least a first direction, wherein said variable application of electrical energy is determined by motion sensed from at least one previous application of electrical energy;

wherein said controller is configured to reject electrical noise in said second resolution conversion according to the number of consecutive conversions having a given differential value from an average value of previous conversion values.

27. In a controller for controlling a process having at least one changing parameter, the improvement comprising:

an analog to digital converter that provides a first faster and lower resolution conversion for changes in said parameter above a predetermined size and a second slower and higher resolution conversion for changes in said parameter below a predetermined size.

28. In a controller for controlling a process having at least one parameter sensed in the presence of noise, the method of reducing the effect of said noise comprising:

calculating an average of said parameter by taking sample readings of said parameter;

eliminating a sample reading from the average calculation if the differential corresponding to the difference between the reading and the average exceeds a certain amount;

using said sample reading if a certain number of previous and consecutive sample readings persist above said differential in a same polarity.

29. An electronic positioning system for an actuator comprising:

an actuator operator configured to produce a change in position in an actuator from a first position to a second position;

a controller that applies energy to the actuator operator to produce motion of the actuator (a) in a first direction from the first position towards the second position and (b) in a second direction from the second position towards the first postion;

an electronic braking system that uses said controller to equally apply energy to the actuator operator in an alternating fashion at a controlled rate and for a controlled time to produce alternating motion of the actuator in the first and second directions until the inertia of the actuator in said first and second directions is substantially balanced.

30. An electronic positioning system for an actuator, comprising:

an actuator operator configured to produce a change in position in an actuator from an initial position to a desired position;

a sensor to ascertain the instantaneous position of the actuator at points intermediate the initial and desired positions;

a controller that applies energy at a rate that is inversely proportional to the temperature of said actuator.

31. The electronic positioning system of claim 30 wherein said temperature is determined according to the amount of energy applied over a given period of time.