CN103576178B - GPS/INS integrated navigation system clocking error modification method based on satellite PPS - Google Patents

Abstract

The invention belongs to integrated navigation technology field, be specifically related to a kind of GPS/INS integrated navigation system clocking error modification method based on satellite PPS.The method of the present invention utilizes GPS atomic clock grade clock correction INS system clock, solve GPS/INS integrated navigation system in prior art and there is the technical problem of clocking error, the short-term stability of INS time and the long-term stability of gps time are combined, makes combined system obtain higher navigation and positioning accuracy.

Description

GPS/INS integrated navigation system clocking error modification method based on satellite PPS

Technical field

The invention belongs to integrated navigation technology field, be specifically related to a kind of GPS/INS based on satellite PPS Integrated navigation system clocking error modification method.

Background technology

Gps satellite receiver be receiving world locational system satellite-signal and definitely space of planes position and High accuracy (atomic clock grade) time standard that receiving gps satellite provides carries out the instrument of time service.Satellite PPS signal is for synchronizing pps pulse per second signal, and its rising edge time conventional indicates whole moment second and correspondence International coordination time UTC.GPS system can provide in real time high accuracy three-dimensional position, three-dimensional velocity and The navigation informations such as time, increasingly extensive in numerous areas application, but under GPS high dynamic condition, The easy losing lock of satellite-signal, dynamically adapting ability is poor, and easily by artificial and non-artificial interference, the external world Signal such as blocks at the environmental effect.

INS inertial navigation system is measured system by inertial sensor accelerometer and gyroscope and is accelerated Degree and angular velocity determine a kind of navigation system of system location information.INS inertial navigation system is just Begin to be completely in autonomous state after alignment, the impact of external environment can be eliminated, but there is gyroscope and acceleration Degree meter error and gravity field model error, and make to increase in time to the error in out position.

GPS/INS integrated navigation system maintain the autonomy of INS inertial navigation system, disguise and The peculiar advantages such as information is comprehensive, bandwidth, overcome again the shortcoming that its navigation error is accumulated in time, special It not to obtain higher navigation and positioning accuracy under carrier is at high dynamic environment yet.

Common GPS/INS integrated navigation system, due to GPS and INS each internal clock frequencies standard Difference, and degree of stability and the accuracy of respective clock are different, how to make GPS and INS time synchronized To obtain high-precision navigation positioning data, it it is this area problem of needing solution badly.

Generally, the data renewal frequency of GPS is 1～10Hz, and the data of INS update Frequency then can reach the frequency marking accuracy of more than l00Hz, INS system and stability is probably measured at 1ppm Level, its 1s timing error is at about 1us.Time in usual system design only GPS Yu INS Clock is synchronized in the INS update cycle (such as 5ms), and improves synchronization accuracy the most further, the most not Consider INS system frequency marking accuracy and stability, it is difficult to realize high accuracy navigation.

Summary of the invention

The technical issues that need to address of the present invention are: GPS/INS integrated navigation system of the prior art is deposited At clocking error, it is difficult to realize high accuracy navigation.

Technical scheme is as described below:

A kind of GPS/INS integrated navigation system clocking error modification method based on satellite PPS, including with Lower step:

Step 1

The CLKINS clock signal of INS temperature compensated crystal oscillator is counted, often receives To the CLKINS clock signal of a INS, produce a SAM signal, the i.e. cycle of SAM signal For a CLKINS clock signal period；

Step 2

The time interval of PPS signal and SAM signal is detected: PPS believes under CLKINS clock signal Moment that number arrives starts to count CLKINS clock signal, nearest with above-mentioned PPS signal SAM letter Number arrive the moment terminate to CLKINS clock signal count；To two PPS signal successively in succession arrived Detecting, above-mentioned time interval is followed successively by N1, N2；

Step 3

To the SAM signal-count between two PPS signal successively in succession arrived, when count results is M Shi Jinhang step 4,

Step 4

When count results arrives M, the cycle of next SAM signal is b CLKINS clock letter Number cycle, b=a-(N2-N1)；The SAM letter produced after this is corrected the SAM signal in cycle Number cycle is still a CLKINS clock signal period；Afterwards, step 2 is returned, it is achieved when continuing side Clock error correction.

Preferably, a=5000, M=200.

The invention have the benefit that

A kind of based on satellite PPS GPS/INS integrated navigation system clocking error correction side of the present invention Method, utilizes GPS(atomic clock grade) clock correction INS system clock, by the INS time short-term The long-term stability of degree of stability and gps time combines, and makes combined system obtain higher navigator fix Precision.

Accompanying drawing explanation

Fig. 1 is that a kind of based on satellite PPS GPS/INS integrated navigation system clocking error of the present invention is repaiied Correction method schematic flow sheet；

Fig. 2 is that PPS compensates navigation system time error sequential chart.

Detailed description of the invention

With embodiment, a kind of based on satellite PPS GPS/INS combination of the present invention is led below in conjunction with the accompanying drawings Boat system clock error correcting method is described in detail.

As it is shown in figure 1, a kind of based on satellite PPS GPS/INS integrated navigation system clock of the present invention Error correcting method, comprises the following steps:

Step 1

Use enumerator T1 that the CLKINS clock signal of INS temperature compensated crystal oscillator is entered Row DIV counts, and often receives the CLKINS clock signal of a INS, and enumerator T1 produces one SAM signal, i.e. the cycle of SAM signal is a CLKINS clock signal period.

Step 2

As in figure 2 it is shown, enumerator T2 receives the CLKINS of INS temperature compensated crystal oscillator The SAM signal that the PPS signal sum counter T1 that clock signal, GPS send produces, and at CLKINS The time interval of PPS signal and SAM signal is detected: the PPS signal arrival moment counts under clock signal Device T2 starts to count CLKINS clock signal, and the SAM signal nearest with above-mentioned PPS signal arrives Moment enumerator T2 terminates to count CLKINS clock signal.To two PPS successively in succession arrived Signal detects, and above-mentioned time interval is followed successively by N1, N2.

Step 3

Enumerator T3 receives the SAM signal of the PPS signal sum counter T1 generation that GPS sends, right SAM signal-count between two PPS signal successively in succession arrived, is carried out when count results is M Step 4,To ensure that the error amount of CLKINS clock signal is 1 It is corrected in Miao.

Step 4

Revise enumerator T1 and produce the cycle of next SAM signal, the cycle of next SAM signal For b CLKINS clock signal period, b=a-(N2-N1).It is corrected the SAM in cycle at this After signal, the SAM signal period that enumerator T1 produces is still a CLKINS clock signal period. Afterwards, step 2 is returned, it is achieved continue side clocking error correction.

In step 2, storage N1, N2 can pass through deposited circuit realiration；In step 4, revise counting Device T1 can be realized by DIV dividing frequency control circuit.

In the present embodiment, a=5000, N1=2, N2=3, M=200, b=5000-(3-2)=4999.

Claims (2)

1. a GPS/INS integrated navigation system clocking error modification method based on satellite PPS, its It is characterised by: comprise the following steps:

Step 1

The CLKINS clock signal of INS temperature compensated crystal oscillator is counted, often receives To the CLKINS clock signal of a INS, produce a SAM signal, the i.e. cycle of SAM signal For a CLKINS clock signal period；

Step 2

The time interval of PPS signal and SAM signal is detected: PPS believes under CLKINS clock signal Moment that number arrives starts to count CLKINS clock signal, nearest with above-mentioned PPS signal SAM letter Number arrive the moment terminate to CLKINS clock signal count；To two PPS signal successively in succession arrived Detecting, above-mentioned time interval is followed successively by N1, N2 CLKINS clock signal period；

Step 3

To the SAM signal-count between two PPS signal successively in succession arrived, when count results is M Shi Jinhang step 4,

Step 4

When count results arrives M, the cycle of next SAM signal is b CLKINS clock letter Number cycle, b=a-(N2-N1)；The SAM letter produced after this is corrected the SAM signal in cycle Number cycle is still a CLKINS clock signal period；Afterwards, step 2 is returned, it is achieved when continuing side Clock error correction.

GPS/INS integrated navigation system clock based on satellite PPS the most according to claim 1 Error correcting method, it is characterised in that: a=5000, M=200.