Gravimetric rotation sensors: dead reckoning, velocity, and heading sensor system for vehicle navigation systems

• US 6,466,887 B1
• Filed: 03/03/2000
• Issued: 10/15/2002
• Est. Priority Date: 03/03/1999
• Status: Active Grant

• Current Assignee: Weinbrenner, Richard L.
• Original Assignee: Weinbrenner, Richard L.
• Inventors: Weinbrenner, Richard L.
• Primary Examiner(s): ASSOUAD, PATRICK J
• Application Number:
  US09/518,305
• Time in Patent Office: 956 Days
• Field of Search: 701/213, 701/214, 701/229, 701/1, 702/141, 702/142, 702/145, 702/147, 702/148, 340/442, 340/988, 731/46, 731/462, 731/464, 731/465
• US Class Current: 702/141
• CPC Class Codes: G01C 21/26 specially adapted for navigation in a road network
• CPC Class Codes: G01P 13/04 Indicating positive or negative direction of a linear movement or clockwise or anti-clockwise direction of a rotational movement
• CPC Class Codes: G01P 15/08 with conversion into electric or magnetic values
• CPC Class Codes: G01P 3/16 by using centrifugal forces of solid masses governors G05D13/10

Abstract

A rotational sensor for use with an in-vehicle navigation system , a navigation system that uses the sensor, and a vehicle with the sensor installed. The rotational sensor is created by placing two gravitational accelerometers configured at 90 degrees with respect to one another and mounted at the center of a vehicle wheel. As this resulting sensor is rotated, sine and cosine signals with a quadrature relationship are generated with respect to the earth'"'"'s gravity vector, from which both rotation and direction of rotation can be determined. These signals may then allow the counting of the turns of the wheel, thus estimating the distance and the rate at which the vehicle has moved. A self-contained version of this device including a transmitter can relay this information to a receiving unit located within the vehicle. When one of these devices is located on each of the steerable wheels of the vehicle, the relative heading-direction of the vehicle may also be estimated.

Claims

1. A gravimetric rotational wheel sensor for use on a mobile vehicle, the mobile vehicle having a body, and front axle engaged to the body, and at least one wheel engaged to the axle, comprising:

a first accelerometer for engagement to the wheel;

a second accelerometer for engagement to the wheel and aligned relatively to sense gravitational force 90 degrees out of synch from said first accelerometer;

a transmitter for engagement to the wheel and for receiving electrical accelerometer output signals representing wheel rotation from said first and said second accelerometers and said transmitter for transmitting said accelerometer output signals;

said first accelerometer and said second accelerometer are within a container and said container may be mounted to the wheel;

a transmitter for allowing remote reporting of wheel position from said first and second accelerometers without the need for hard wiring;

a microprocessor-based electronic circuit for signal processing and data correlation;

said container configured to ensure said first accelerometer and said second accelerometer are located near the center of the wheel when said container is engaged to the wheel; and

said microprocessor-based electronic circuit for signal processing and data correlation has a generator that may convert sensed rotational motion of the wheels to electric power.

2. A gravimetric rotational wheel sensor for use on a mobile vehicle, the mobile vehicle having a body, and front axle engaged to the body, and at least one wheel engaged to the axle, comprising:

a first accelerometer for engagement to the wheel;

a second accelerometer for engagement to the wheel and aligned relatively to sense gravitational force 90 degrees out of synch from said first accelerometer;

a transmitter for engagement to the wheel and for receiving electrical accelerometer output signals representing wheel rotation from said first and said second accelerometers and said transmitter for transmitting said accelerometer output signals;

said first accelerometer and said second accelerometer are within a container and said container may be mounted to the wheel;

a transmitter for allowing remote reporting of wheel position from said first and second accelerometers without the need for hard wiring;

a microprocessor-based electronic circuit for signal processing and data correlation;

said container configured to ensure said first accelerometer and said second accelerometer are located near the center of the wheel when said container is engaged to the wheel;

said first and second accelerometer provide two output wave results in a quadrature waveform in a 90 degree phase relationship between said two outputs when installed on a wheel and the wheel rotates; and

said microprocessor-based electronic circuit for signal processing and data correlation has a centripetal bias signal processing circuit portion programmed for accounting for offset from center of the wheel upon mounting.

3. The wheel sensor of claim 2, wherein:

said centripetal bias signal processing circuit portion determines bias due to offset by use of formula;

$g=3.207\times <br><br>r\times <br><br>{\left[\frac{v}{D}\right]}^2$

 

where

r is the radius of the position of the accelerometer sensor;

g is the centripetal acceleration force the accelerometer is subjected to in G'"'"'s;

v is the speed of the vehicle in MPH; and

D is the diameter of the vehicle wheel in inches.

4. The wheel sensor of claim 2, wherein:

said quadrature waveform is output of a quadrature combining and tracking circuitry of said microprocessor-based electronic circuit for signal processing and data correlation for combining said first and second accelerator output signals to yield the wheel rotation direction and position.

5. The wheel sensor of claim 4, additionally comprising:

a filter in series with said centripetal bias circuit portion.

6. The wheel sensor of claim 5, additionally comprising:

a data correlation circuit electrically engaged to said quadrature combining and tracking circuitry for correlating said combined first and second accelerator output signals;

a master clock engaged to said data correlation circuit and for sampling said first and second accelerator output signals at a rate greater than sensed rotational rate of the wheel; and

data packet formation circuitry engaged to said data correlation circuit and said transmitter.

7. The wheel sensor of claim 6, wherein:

said master clock samples data at greater than or equal to four times the rate of rotation of the wheel.

16. The wheel sensor of claim 3, wherein:

said centripetal bias signal processing circuit portion uses bias as a measurement of rate rotation of the wheel.

8. A mobile vehicle, comprising:

a body;

front axle engaged to said body;

said front axle engaged to a left front steerable wheel and a right front steerable wheel, each of said wheels having an inner hub for mounting to said front axle;

a navigation system within said body;

a first gravimetric rotational wheel sensor engaged to a first of said front wheels, comprising;

a first accelerometer;

a second accelerometer aligned relatively to sense gravitational force 90 degrees out of synch from said first accelerometer; and

a transmitter for receiving electrical accelerometer output signals representing wheel rotation from said first and said second accelerometers and said transmitter for transmitting said accelerometer output signals;

a receiver and microprocessor system for receiving and error checking said electrical accelerometer output signals from said first front wheel transmitter;

said receiver engaged to said navigation system to provide said electrical accelerometer output signals to said navigation system providing said navigation system an indication of distance traveled and direction of first front wheel rotation;

a second gravimetric rotational wheel sensor engaged to a second of said front wheels, comprising;

a third accelerometer;

a fourth accelerometer aligned relatively to sense gravitational force 90 degrees

out of synch from said third accelerometer; and

a second transmitter for receiving electrical accelerometer output signals representing wheel rotation from said third and said fourth accelerometers and said second transmitter for transmitting said accelerometer output signals to said receiver; and

said receiver, microprocessor, and navigation system programmed to process output signals from said first and second rotational wheel sensors to determine distance traveled and changes in vehicle direction due to sensed relative wheel rotation.

9. The vehicle of claim 8, wherein:

said receiver, microprocessor, and navigation system detects changes in vehicle direction by use of formula;

$\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\theta <br><br>}=\frac{\left(\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>S_{\mathrm{Left1}}-\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>S_{\mathrm{Left2}}\right)-\left(\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>S_{\mathrm{Right1}}-\mathrm{\Delta <br><br>}<br><br>\text{\hspace{1em}<br><br>}<br><br>S_{\mathrm{Rightt2}}\right)}{B}$

 

where

Δ

S_Left1 is the first sample position of said left wheel

Δ

S_Left2 is the second sample position of said left wheel

Δ

S_Right1 is the first sample position of said right wheel

Δ

S_Right2 is the second sample position of said right wheel

B=distance from the track of said left wheel to the track of said right wheel all distance units must be in the same units, including B.

10. The vehicle of claim 9, wherein:

said first accelerometer and said second accelerometer are within a container, said third accelerometer and said fourth accelerometer are within a container, and said containers each have mounting means for mounting to said respective wheels;

said mounting means configured to ensure said accelerometers are located near the center of said respective wheels.

11. The vehicle of claim 10, wherein:

said transmitters are programmed to not interfere with other transmitters and allow differentiation by said receiver by use of a spectrum allocation technique.

12. The vehicle of claim 11, wherein:

said spectrum allocation technique is that each said transmitter is at a unique frequency of transmission.

13. The vehicle of claim 11, wherein:

said spectrum allocation technique is a spread time slot approach.

14. The vehicle of claim 13, wherein:

said spectrum allocation technique is a spread spectrum approach.

15. A gravimetric rotational wheel sensor for use on a mobile vehicle, the mobile vehicle having a body, and front axle engaged to the body, and at least one wheel engaged to the axle, comprising:

an accelerometer for engagement to the wheel; and

a transmitter for engagement to the wheel and for receiving electrical accelerometer output signals representing both static and dynamic wheel position and rotation from said accelerometer and said transmitter for transmitting said accelerometer output signal.

17. A gravimetric rotational wheel sensor for use on a mobile vehicle, the mobile vehicle having a body, and front axle engaged to the body, and at least one wheel engaged to the axle, comprising:

a first accelerometer for engagement to the wheel;

a second accelerometer for engagement to the wheel and aligned relatively to sense gravitational force 90 degrees out of synch from said first accelerometer; and

a transmitter for engagement to the wheel and for receiving electrical accelerometer output signals representing wheel radial position in both static and dynamic conditions and amount of rotation upon rotation from said first and said second accelerometers and said transmitter for transmitting said accelerometer output signals.

18. The wheel sensor of claim 17, additionally comprising:

a transmitter for allowing remote reporting of wheel position from said first and second accelerometers without the need for hard wiring.

19. The wheel sensor of claim 18, additionally comprising:

an electronic circuit for signal processing and data correlation.

20. The wheel sensor of claim 19, wherein:

said first and second accelerometer provide two output wave results in a quadrature waveform in a 90 degree phase relationship between said two outputs when installed on a wheel and the wheel rotates.

21. The wheel sensor of claim 20, wherein:

said electronic circuit for signal processing and data correlation having a centripetal bias signal processing circuit portion programmed for accounting for offset from center of the wheel upon mounting.