Rotational angle detector which prevents controlled system from being improperly controlled

• US 20030023400A1
• Filed: 07/23/2002
• Published: 01/30/2003
• Est. Priority Date: 07/30/2001
• Status: Active Grant

• Current Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Kato, Hironori, Sanpei, Yoshio
• Granted Patent: US 6,778,939 B2
• Time in Patent Office: Days
• US Class Current: 702/151
• CPC Class Codes: B62D 15/02 Steering position indicators ; Steering position determination; Steering aids
• CPC Class Codes: G01D 5/24409 Interpolation using memories
• CPC Class Codes: G01D 5/24461 by redundancy or plausibility

Abstract

A rotational angle detector which comprises: a rotational angle detecting section which detects an angle detection signal correspondent to a rotational state of a rotor in a short cycle and feeds it to a control section; the control section which calculates the fed angle detection signal and sends an angle set signal through a controller to a controlled system; and a memory which stores the angle detection signal temporarily and also stores an allowable maximum angle value for the angle detection signal, wherein the control section makes the output cycle for the angle set signal longer than the detection cycle for the angle detection signal and counts the number of times when the angle detection signal as fed within the long output cycle for the angle detection signal is beyond the allowable maximum angle value and, if it decides that the count is beyond a preset number, outputs an abnormality signal instead of the angle set signal.

Claims

1. A rotational angle detector comprising:

a rotational angle detecting section which detects an angle detection signal correspondent to a rotational state of a rotor in a short cycle and feeds the angle detection signal to a control section;

the control section which calculates the angle detection signal fed from the rotational angle detecting section and sends an angle set signal through a controller to a controlled system; and

a memory which stores the angle detection signal temporarily and also stores an allowable maximum angle value for the angle detection signal,

wherein the control section makes an output cycle for the angle set signal longer than a detection cycle for the angle detection signal and counts a number of times when the angle detection signal as fed within the long output cycle for the angle detection signal is beyond the allowable maximum angle value and, if the count is judged as being beyond a preset number, outputs an abnormality signal instead of the angle set signal.

2. The rotational angle detector according to claim 1, wherein the detection cycle for the angle detection signal is 400 μ

sec and the output cycle for the angle set signal is 10 msec.

3. The rotational angle detector according to claim 1, wherein the count is judged as being beyond the preset number when two out of three consecutive counts are found beyond the preset number.

4. The rotational angle detector according to claim 1, wherein the count is judged as being beyond the preset number when six out of 64 consecutive counts are found beyond the preset number.

5. A rotational angle detector comprising:

a rotational angle detecting section which detects an angle detection signal correspondent to a rotational state of a rotor and feeds the angle detection signal to a control section;

the control section which calculates the angle detection signal fed from the rotational angle detecting section to generate an angle set signal and sends the generated angle set signal through a controller to a controlled system; and

a memory which stores an allowable maximum setting,

wherein the control section concurrently performs a first calculation step and a second calculation step for the fed angle detection signal fed from the rotational angle detecting section to generate a first angle set signal and a second angle set signal, calculates the difference between the first angle set signal and second angle set signal, compares the calculated difference with the allowable maximum setting, and if the calculated difference is judged as being above the allowable maximum setting, outputs an abnormality signal in addition to the angle set signal.

6. The rotational angle detector according to claim 5, wherein the control section performs the first calculation step and the second calculation step using different lookup tables.

7. The rotational angle detector according to claim 5, wherein the control section performs the first calculation step and the second calculation step using different algorithms.

8. The rotational angle detector according to claim 5, wherein the control section detects the angle detection signal in a short cycle and outputs the angle set signal in a cycle longer than the detection cycle for the angle detection signal.

9. The rotational angle detector according to claim 5, wherein the first calculation step and the second calculation step are performed by different control sections.