Apparatus and method for detecting the cessation of motion of a body

• US 4,409,836 A
• Filed: 11/13/1981
• Issued: 10/18/1983
• Est. Priority Date: 11/13/1981
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Comroe, Richard A., van den Heuvel, Anthony P., Kotzin, Michael D.
• Primary Examiner(s): Gill, James J.
• Application Number:
  US06/321,342
• Time in Patent Office: 704 Days
• Field of Search: 73/504, 73/505, 73/518, 324/160
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5642 using vibrating bars or beams

Abstract

An apparatus and a method are provided for determining when a moving body assumes a motionless state. A rate of turn sensor is attached to the moving body. A signal indicating that the body is substantially motionless is generated when the rate of turn signal generated by the sensor is substantially constant.

Claims

1. An apparatus for detecting when a moving body assumes a substantially motionless state comprising:

rate of turn sensor means attached to said body for generating a rate of turn signal exhibiting an amplitude which is proportional to the rate of turn of said body;

differentiator means, electrically coupled to said sensor means, for differentiating said rate of turn signal to generate a differentiated signal;

absolute value circuit means, electrically coupled to said differentiator means, for generating an absolute value signal equal to the absolute value of said differentiated signal;

limiter means, electrically coupled to said absolute value circuit means, for limiting the amplitude of said absolute value signal to a predetermined signal level, thereby generating a limited signal;

filtering means, electrically coupled to said limiter means, for filtering said limited signal, thereby generating an filtered signal, and

comparator means, electrically coupled to said filter means, for generating a first signal when said filtered signal is less than a predetermined voltage level to indicate that said body is substantially motionless.

2. The apparatus of claim 1 wherein said rate of turn sensor means comprises a rate gyro.

3. The apparatus of claim 1 wherein said rate of turn sensor means comprises a vibrating bar rate gyro.

4. The apparatus of claim 1 wherein said filtering means comprises a low pass filter.

5. A method of detecting when a moving body assumes a substantially motionless state comprising the steps of;

A. sensing the rate of turn of said body to generate a rate of turn signal exhibiting an amplitude which is proportional to the rate of turn of said body;

B. differentiating said rate of turn signal to generate a differentiated signal;

C. generating an absolute value signal equal to the absolute value of said differentiated signal;

D. limiting the amplitude of said absolute value signal to a predetermined signal level to generate a limited signal;

E. filtering said limited signal to generate an filtered signal, and

F. comparing said filtered signal to a predetermined voltage level to generate a first signal when said filtered signal is less than said predetermined voltage level to indicate that said body is substantially motionless.

6. The method of claim 5 step E comprises low pass filtering said limited signal to generate a filtered signal.