Method of correcting zero point of gyro and apparatus therefor

• US 5,065,612 A
• Filed: 09/08/1989
• Issued: 11/19/1991
• Est. Priority Date: 09/28/1988
• Status: Expired due to Fees

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Hirano, Kazuo, Ooka, Akihiro
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US07/404,402
• Time in Patent Office: 802 Days
• Field of Search: 73/504, 73/1 D, 364/571.02
• US Class Current: 73/1.77
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices

Abstract

A method of correcting a zero point of a gyro, comprises the steps of detecting a speed of a moving body and outputting a speed signal corresponding to the speed; determining with the speed signal whether the moving body is at a stopping condition; computing an average value of output values of the gyro within a constant time in which the moving body is at the stopping condition, and setting the average value to a new zero point of the gyro; and correcting an output value of the gyro with the new zero point. An apparatus for correcting a zero point of a gyro, comprises a speed sensor for detecting a speed of a moving body and outputting a speed pulse signal corresponding to the speed; a flip-flop circuit which is set by the speed pulse signal of the speed sensor; and a zero-point correcting circuit wherein it is determined with a level of an output of the flip-flop circuit and with an output of a timer whether the moving body is at a stopping condition and wherein a zero point of the gyro is corrected with an average value of outputs of the gyro at the same time the moving body is at the stopping condition, the zero point correcting circuit outputting a clear signal to the flip-flop circuit, the flip-flop circuit being cleared by the clear signal and then set by the speed pulse signal.

Claims

1. A method of correcting a zero point of a gyro, comprising the steps of:

detecting a speed of a moving body and outputting a speed signal corresponding to said speed;

when said speed signal is less than a predetermined reference for a first predetermined period of time from a certain time, determining that said moving body is in a stopped condition;

computing an average value of output values of the gyro for a second predetermined period of time immediately after said first predetermined period of time, and setting a zero point correction value to said average value;

determining whether said speed signal is less than said predetermined reference for a third predetermined period of time immediately after said second predetermined period of time; and

when said speed signal is less than said predetermined reference for all said first, second and third predetermined periods of time, setting the zero point of the gyro to an updated value corresponding to said zero point correction value and correcting an output value of the gyro with said updated value of said zero point.

2. A method as set forth in claim 1, wherein said moving body comprises a vehicle.

3. An apparatus for correcting a zero point of a gyro, comprising:

a speed sensor for detecting a speed of a moving body and outputting a speed pulse signal corresponding to the speed;

a flip-flop circuit which is set by said speed pulse signal of said speed sensor; and

a zero-point correcting circuit which determines from a level of an output of said flip-flop circuit whether there exists said speed pulse for a first predetermined period of time from a certain time, and determines that said moving body is in a stopped condition, when no speed pulse signal occurs for said first predetermined period of time, and computes an average value of output values of said gyro for a second predetermined period of time immediately after said first predetermined period of time and sets a zero point correction value to said average value, and determines from a level of an output of said flip-flop circuit whether there exits said speed pulse for a third predetermined period of time immediately after said second predetermined period of time, and sets the zero point of said gyro to an updated value corresponding to said zero point correction value and corrects an output value of the gyro with said updated value, when no speed pulse signal occurs for all said first, second and third predetermined period of time, and the zero point correcting circuit outputting a clear signal to said flip-flop circuit, the flip-flop circuit being cleared by said clear signal and then set by said speed pulse signal.

4. An apparatus as set forth in claim 3, wherein said moving body comprises a vehicle.