Method for initializing position with an encoder

• US 20030222798A1
• Filed: 06/03/2002
• Published: 12/04/2003
• Est. Priority Date: 06/03/2002
• Status: Active Grant

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Inventors: Floros, John H., Jordan, Paul T., Sarafopoulos, Nick
• Granted Patent: US 6,914,543 B2
• Time in Patent Office: Days
• US Class Current: 341/3
• CPC Class Codes: G01D 5/2457 Incremental encoders having reference marks
• CPC Class Codes: H03M 1/206 using a logic interpolation circuit
• CPC Class Codes: H03M 1/303 Circuits or methods for processing the quadrature signals
• CPC Class Codes: H03M 1/308 with additional pattern means for determining the absolute position, e.g. reference marks
• CPC Class Codes: H03M 1/645 for position encoding, e.g. using resolvers or synchros H03M1/485 takes precedence

Abstract

A method for detecting an absolute rotational position of an electromechanical device or the at least one component thereof comprising determining a first absolute position of the electromechanical device or the at least one component thereof based on a commutation index signal, obtaining a Z-index signal, and determining a second absolute position of the electromechanical device or the at least one component thereof based on the Z-index signal. The method initially determines a coarse rotational position of the electromechanical device such as a rotor or steering wheel based on the commutation index signal. When a device'"'"'s position is first initialized by a commutation index signal before the Z-index pulse is detected, the device'"'"'s position is re-initialized upon detection of the Z-Index pulse to provide a more accurate absolute device rotational position.

Claims

1. A method for detecting an absolute rotational position of an electromechanical device or at least one component thereof comprising:

using a pair of signals to determine a relative position of the electromechanical device or the at least one component thereof from a starting point;

obtaining a commutation index signal;

determining a first absolute position of the electromechanical device or the at least one component thereof based on the commutation index signal;

obtaining a Z-index signal; and

determining a second absolute position of the electromechanical device or the at least one component thereof based on the Z-index signal.

2. The method of claim 1, wherein a coarse absolute rotational position of a rotor or steering wheel is determined based on the commutation index signal.

3. The method of claim 2 further comprising determining the absolute rotational position of the rotor or steering wheel based on the Z-index signal.

4. The method of claim 1, wherein the position of the electromechanical device or the at least one component thereof is re-initialized when the Z-Index signal is detected, and the position the electromechanical device or the at least one component thereof is initialized by a commutation index signal before the Z-index signal is detected.

5. The method of claim 1, wherein the commutation index signal occurs after each rotational motion by the electromechanical device or the at least one component thereof of between about 15-90 electrical degrees.

6. The method of claim 1, wherein the commutation index signal occurs after each rotational motion by the electromechanical device or the at least one component thereof of about 60 electrical degrees.

7. The method of claim 1, wherein a reinitialization of the position of the electromechanical device or the at least one component thereof is prevented after the Z-index signal has initialized the position of the electromechanical device or the at least one component thereof for each revolution of the electromechanical device or the at least one component thereof.

8. The method of claim 1, wherein the commutation index or Z-index signal is obtained using at least one encoder.

9. The method of claim 8, wherein the encoder is a rotary or an optical encoder.

10. The method of claim 1, wherein the pair of signals constitute a quadrature encoder signal.

11. The method of claim 1 comprising using an encoder to obtain the signals corresponding to a relative position of the electromechanical device or the at least one component thereof.

12. The method of claim 1, wherein a phase difference of +90°

between the pair of signals corresponds to a clockwise rotation of the electromechanical device or the at least one component thereof, and a phase difference of −

90°

corresponds to a counterclockwise rotation.

13. The method of claim 2, wherein the coarse rotational position of the electromechanical device or the at least one component thereof is determined every 15-90 electrical degrees.

14. The method of claim 2, wherein the coarse rotational position of the electromechanical device or the at least one component thereof is determined about every 60 electrical degrees.