Apparatus and method for minimizing limit cycle using complementary filtering techniques

• US 5,015,934 A
• Filed: 09/25/1989
• Issued: 05/14/1991
• Est. Priority Date: 09/25/1989
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Inventors: Kral, Kevin D., Holley, Steven R., Cunningham, David C.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): BERGMANN, SAUL
• Application Number:
  US07/415,803
• Time in Patent Office: 596 Days
• Field of Search: 318/611, 318/585, 318/584, 364/414, 250/201
• US Class Current: 318/611
• CPC Class Codes: G05B 19/33 using an analogue measuring device
• CPC Class Codes: G05B 2219/33268 D-A, A-D
• CPC Class Codes: G05B 2219/37313 Derive speed from position
• CPC Class Codes: G05B 2219/37473 Resolver
• CPC Class Codes: G05B 2219/41423 Noise filter as function of rate of displacement, speed, for stabilisation
• CPC Class Codes: G05D 3/20 using a digital comparing device

Abstract

The apparatus controls the positioning of a device in response to a commanded input signal, and comprises an element for moving the device in response to an error signal. A sensor component determines the actual position of the device, the sensor component outputting a primary signal and a derivative signal corresponding to the actual position and velocity of the device, respectively. A complementary filter system filters the primary signal and the derivative signal to generate a derived position signal, the derived position signal being combined with the commanded input signal thereby generating the error signal. The filtering results in effectively increasing the resolution of the sensor component thereby reducing the limit cycle caused by quantization of the sensor component.

Claims

1. An apparatus for controlling the positioning of a device in response to a commanded input signal, said apparatus comprising:

(a) means for moving the device in response to an error signal;

(b) sensor means for determining the actual position of the device, said sensor means outputting a quantized primary signal and a derivative signal corresponding to the actual position and velocity of the device, respectively; and

(c) complementary filter system means, for filtering the primary signal and the derivative signal to generate a derived position signal, the derived position signal being combined with the commanded input signal to generate the error signal, whereby the filtering results in effectively increasing the resolution of the sensor means thereby reducing the limit cycle caused by quantization of the sensor means.

2. An apparatus for controlling the positioning of a device according to claim 1, wherein said complementary filter system means comprises:

(a) first filter means for filtering said primary signal;

(b) second filter means for filtering said derivative signal,wherein said first filter means is the complement of the second filter means, and the second filter means is the complement of the first filter means; and

(c) means for combining the output signal of said first and second filter means to generate the derived position signal.

3. An apparatus for controlling the positioning of a devise according to claim 2, wherein said complementary filter system means has a unity gain transfer function over a predetermined frequency range of interest.

4. An apparatus for controlling the positioning of a device according to claim 3, wherein said apparatus further comprises:

compensation means, interposed in the apparatus before the means for moving and in a position to receive the error signal, for causing the steady state position error of the apparatus to be driven to zero.

5. An apparatus for controlling the positioning of a device according to claim 4, wherein said means for moving comprises:

(a) torque motor drive; and

(b) torque motor operatively connected to the device to be positioned.

6. An apparatus for controlling the positioning of a device according to claim 1, wherein said apparatus further comprises:

compensation means, interposed in the apparatus before the means for moving and in a position to receive the error signal, for causing the steady state position error of the apparatus to be driven to zero.

7. An apparatus for controlling the positioning of a device in response to a commanded input signal, said apparatus comprising:

(a) means for moving the device in response to an error signal;

(b) sensor means for determining the actual position of the device, said sensor means outputting an analog position signal corresponding to the actual position of the device;

(c) a differentiator means, operatively connected to said sensor means, for generating an analog velocity signal;

(d) converter means, operatively connected to said sensor means and to said differentiator means, for converting said analog position signal to a digital position signal and said analog velocity signal to a digital velocity signal; and

(e) complementary filter system means, operatively connected to said converter means to receive said digital position signal and said digital velocity signal, for filtering said digital position signal and said digital velocity signal to generate a derived position signal, the derived position signal being combined with the commanded input signal to generate the error signal, whereby the filtering results in effectively increasing the resolution of the sensor means thereby reducing the limit cycle caused by quantization of the sensor means.

8. An apparatus for controlling the positioning of a device according to claim 7, wherein said complementary filter system means comprises:

(a) first filter means for filtering said digital position signal, generating a first output signal;

(b) second filter means for filtering said digital velocity signal, generating a second output signal, wherein said first and second filter means are the complement of the other; and

(c) means for combining the first and second output signals of said first and second filter means to generate the derived position signal.

9. An apparatus for controlling the positioning of a device according to claim 8, wherein said complementary filter means has a unity gain transfer function.

10. An apparatus for controlling the positioning of a device according to claim 9, wherein said apparatus further comprises:

compensation means, interposed in the apparatus before the means for moving and in a position to receive the error signal, for causing the steady state position error of the apparatus to be driven to zero.

11. An apparatus for controlling the positioning of a device according to Claim 10, wherein said means for moving comprises:

(a) torque motor drive; and

(b) torque motor operatively connected to the device to be positioned.

12. An apparatus for controlling the positioning of a device according to claim 7, wherein said apparatus further comprises:

compensation means, interposed in the apparatus before the means for moving and in a position to receive the error signal, for causing the steady state position error of the apparatus to be driven to zero.