Global positioning system and dead reckoning (GPSandDR) integrated navigation system

1. A global positioning system and dead reckoning (GPS&DR) integrated navigation system comprising:

a GPS receiver coupled to a moving object for periodically calculating GPS navigation information of said moving object according to satellite signals;

a DR system coupled to said moving object for periodically calculating DR navigation information of said moving object by integrating moving information of said moving object with reference position and orientation from said DR system;

a filter coupled to said GPS receiver and said DR system for periodically calculating navigation information of said moving object, wherein said filter gets observation information by integrating said GPS navigation information and said DR navigation information according to a weight value of said GPS navigation information and a weight value of said DR navigation information, and said filter calculates a current navigation information by integrating said observation information with previous navigation information from a plurality of previous cycles; and

a weight module coupled to said GPS receiver for calculating said weight value of said GPS navigation information and said weight value of said DR navigation information based on the number of said satellite signals with a carrier-to-noise ratio above a first predetermined threshold.

2. The GPS&DR integrated navigation system of claim 1 , further comprising:

a filter coupled to said GPS receiver for determining whether said satellite signals received at said GPS receiver are reliable according to said carrier-to-noise ratio of said satellite signals and a linear velocity of said moving object.

3. The GPS&DR integrated navigation system of claim 1 , wherein said weight module calculates said weight value of said GPS navigation information and said weight value of said DR navigation information according to a position dilution of precision of said satellite signals if said number of said satellite signals with said carrier-to-noise ratio above said first predetermined threshold is greater than a second predetermined threshold.

4. The GPS&DR integrated navigation system of claim 1 , wherein said weight module sets said weight value of said GPS navigation information with a first predetermined value and sets said weight value of said DR navigation information with a second predetermined value if said number of said satellite signals with said carrier-to-noise ratio above said first predetermined threshold is less than a second predetermined threshold.

5. The GPS&DR integrated navigation system of claim 1 , further comprising:

a filter coupled to said GPS receiver for reducing noise within said GPS navigation information.

6. The GPS&DR integrated navigation system of claim 1 , wherein said reference position and orientation are updated said GPS navigation information if an average value of linear velocity of said moving object measured by said GPS receiver is greater than a second predetermined threshold, and the number of said satellite signals with said carrier-to-noise ratio above a third predetermined threshold is greater than a fourth predetermined threshold.

7. The GPS&DR integrated navigation system of claim 1 , further comprising:

A gyroscope coupled to said moving object for measuring an angular velocity of said moving object; and

A milemeter coupled to said moving object for measuring a linear velocity of said moving object;

wherein said moving information of said moving object comprises said angular velocity and said linear velocity.

8. The GPS&DR integrated navigation system of claim 7 , wherein said gyroscope comprises a filter for estimating values of parameters of said gyroscope according to said angular velocity measured by said gyroscope and an angular velocity measured by said GPS receiver, wherein said gyroscope reduces deviation of said angular velocity according to said estimated values of said parameters.

9. The GPS&DR integrated navigation system of claim 7 , wherein said milemeter comprises a filter for estimating values of parameters of said milemeter according to said linear velocity measured by said milemeter and a linear velocity measured by said GPS receiver, wherein said milemeter reduces deviation of said linear velocity according to said estimated values of said parameters.

10. The GPS&DR integrated navigation system of claim 1 , further comprising a display screen for displaying said navigation information of said moving object from said filter.

11. A method for providing navigation information of a moving object through a global positioning system and dead reckoning (GPS&DR) integrated navigation system, said method comprising the steps of:

calculating, through a GPS receiver, GPS navigation information of said moving object according to satellite signals received by said GPS receiver;

calculating, through a DR system, DR navigation information of said moving object by integrating moving information of said moving object with reference position and orientation from said DR system;

getting, through a filter, observation information by integrating said GPS navigation information and said DR navigation information according to a weight value of said GPS navigation information and a weight value of said DR navigation information;

calculating, through said filter, a current navigation information by integrating said observation information with previous navigation information from a plurality of previous cycles; and

calculating, through a weight module, said weight value of said GPS navigation information and said weight value of said DR navigation information based on the number of said satellite signals with a carrier-to-noise ratio above a first predetermined threshold.

12. The method of claim 11 , further comprising the step of:

determining whether said satellite signals received at said GPS receiver are reliable according to said carrier-to-noise ratio of said satellite signals and a linear velocity of said moving object.

13. The method of claim 11 , wherein the step of calculating said weight value of said GPS navigation information said weight value of said DR navigation information according to said GPS navigation information further comprises the steps of:

calculating said weight value of said GPS navigation information and said weight value of said DR navigation information according to a position dilution of precision of said satellite signals if said number of said satellite signals with said carrier-to-noise ratio above said first predetermined threshold is greater than a second predetermined threshold; and

setting said weight value of said GPS navigation information with a first predetermined value and setting said weight value of said DR navigation information with a second predetermined value if said number of said satellite signals with said carrier-to-noise ratio above said first predetermined threshold is less than said second predetermined threshold.

14. The method of claim 11 , further comprising the step of:

reducing noise within said GPS navigation information by a filter.

15. The method of claim 11 , further comprising the steps step of:

updating said reference position and orientation according to said GPS navigation information if an average value of linear velocity of said moving object measured by said GPS receiver is greater than a second predetermined threshold, and the number of said satellite signals with said carrier-to-noise ratio above a third predetermined threshold is greater than a fourth predetermined value threshold.

16. The method of claim 11 , further comprising the steps of:

measuring an angular velocity of said moving object by a gyroscope; and

measuring a linear velocity of said moving object by a milemeter;

wherein said moving information of said moving object comprises said angular velocity and said linear velocity.

17. The method of claim 16 , further comprising the steps of:

estimating values of parameters of said gyroscope according to said angular velocity measured by said gyroscope and an angular velocity indicated in said GPS navigation information; and

reducing deviation of said angular velocity according to said estimated parameters.

18. The method of claim 16 , further comprising the step of:

estimating values of parameters of said milemeter according to said linear velocity measured by said milemeter and a linear velocity indicated in said GPS navigation information; and

reducing deviation of said linear velocity according to said estimated parameters.

19. The method of claim 11 , further comprising the step of displaying said navigation information of said moving object on a display screen.