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1. WO1997024584 - A ZERO MOTION DETECTION SYSTEM FOR IMPROVED VEHICLE NAVIGATION SYSTEM

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

CLAIMS:
1. An improved zero motion detection system for a vehicle navigation system, said zero motion detection system comprising:
a motion detection sensor which provides motion signals with an offset; and
said zero motion detection system system compares at least one sample of said motion signals with a threshold to determine a zero motion state, and if in said zero motion state, said detection system determines said offset.
2. The zero motion detection system of claim 1 including a zero motion signal, said detection system produces a zero motion signal to lock heading changes and calibrate velocity information.
3. The zero motion detection system of claim 2 wherein said detection system resolves ambiguity in GPS velocity information.
4. The zero motion detection system o claim 1 wherein said detection system determines said offset by averaging samples of said motion signals.
5. The zero motion detection system of claim 1 wherein said detection system compares at least two samples of said motion signals with a threshold to determine said zero motion state.
6. The zero motion detection system of claim 1 wherein said motion detection sensor includes an orthogonal axes accelerometer, said system determines a zero offset for at least one axes of said accelerometer if said detection system is in said zero motion state.
7. The zero motion detection system of claim 1 wherein said motion detection sensor includes a gyro.
8. The zero motion detection system of claim 1 wherein said motion detection sensor includes a piezoelectric device.
9. An improved zero motion detection system for a vehicle navigation system, said zero motion detection system comprising:
an orthogonal axes accelerometer which provides motion signals with an offset for each axis of said accelerometer; and said zero motion detection system system compares at least two samples of said motion signals with a threshold to determine a zero motion state, and if in said zero motion state, said detection system determines a zero offset for each axis of said accelerometer by averaging samples of said motion signals for each axis, and said zero motion detection system provides a zero motion signal to lock heading changes and calibrate velocity information.
10. A method of detecting a zero motion state, said method comprising the steps of:
providng a motion sensor signal;
determining a zero motion state by comparing at least one sample of said motion sensor signal with a threshold; and
using at least one of said samples to determine said offset if said zero motion state is detected.
1 1. The method of claim 10 further including the step of providing a zero motion signal upon detecting a zero motion state to resolve ambiguity of GPS velocity measurements.
12. The method of claim 10 further including the step of:
providing a zero motion signal; and
lock heading changes and calibrate velocity information in response to said zero motion signal.
13. The method of claim 10 wherein said step of determining said zero motion state includes comparing at least two samples of said motion signals with said threshold to determine said zero motion state.
14. The method of claim 1 wherein said step of using includes the step of averaging said samples.
15. The method of claim 10 wherein said step of providing motion signlas includes employing an orthogonal axes accelerometer which provides motion signals and an offset for at least one axes of said accelerometer.
16. The method of claim 10 wherein said step of providing motion signlas includes employing a gyro.

17 The method of claim 10 wherein said step of providing motion signlas includes employing a piezoelectric device
1 8 A method of detecting a zero motion state, said method comprising the steps of:
providing motion signals and an offset for at least one axes of an orthogonal axes accelerometer;
determining a zero motion state by comparing at least two samples of said motion signals with a threshold;
providing a zero motion signal;
locking heading changes and calibrating velocity information in response to said zero motion signal; and
averaging said samples to determine said offset if said zero motion state is detected