A sky direction channel damping method for correcting accelerometer zero bias based on FOG-SINS

Abstract

A sky direction channel damping method for correcting accelerometer zero offset based on FOG-SINS, by establishing a new model, taking the height of the satellite and the sky direction velocity as the external reference quantity, estimating the sky direction accelerometer zero offset error, and entering the corrected sky direction specific force information into the damping feedback loop, the convergence speed of the sky direction velocity error and height error estimation in the loop is accelerated, thereby improving the sky direction channel tracking accuracy of the FOG-SINS inertial navigation equipment, solving the problem that in the original sky direction channel damping model, only the height is taken as the main reference quantity, the sky direction specific force error is not corrected, resulting in poor sky direction channel tracking accuracy and low measurement accuracy during the movement of the carrier.

Description

Technical Field

[0001] This invention relates to a method for correcting accelerometer zero bias and upward channel damping based on FOG-SINS, which is mainly used in the field of airborne fiber optic strapdown inertial navigation. Background Technology

[0002] The FOG-SINS inertial navigation system is a high-precision strapdown inertial navigation system based on fiber optic gyroscopes and quartz accelerometers. As the main navigation and measurement device for UAV platforms, it can provide real-time information on the angular and linear motion of the carrier, and is sensitive to the carrier's position, speed, and attitude information for airframe control.

[0003] During flight, the aircraft provides the FOG-SINS inertial navigation system with real-time satellite navigation speed, position information, and other onboard auxiliary equipment information such as barometers, for the purpose of correcting the combined navigation error of the FOG-SINS inertial navigation system.

[0004] Typically, FOG-SINS inertial navigation devices employ Kalman filtering for integrated navigation, establishing output correction based on horizontal velocity and position information for 4D observations, or feedback correction based on triaxial velocity and position information for 6D observations. Considering the accuracy of instrument error estimation and correction for high-precision inertial measurement equipment, output correction methods are often used. In this case, damping methods are required in the upward channel direction to suppress error divergence.

[0005] Existing altitude channel damping methods only use altitude information as the primary observation and do not correct for errors in the accelerometer. When the accelerometer has residual zero bias, this error will be reflected in the altitude velocity and altitude during the vehicle's motion. Furthermore, since the system damping coefficient is constant, while the error of the external altitude reference information is time-varying during flight, this damping method requires convergence time during motion changes and cannot quickly track the observed information in a short time. As a result, when the aircraft undergoes large-amplitude movements or the satellite navigation quality is poor, the FOG-SINS inertial navigation equipment has low measurement accuracy in the altitude channel. Therefore, it is necessary to find a method that can effectively and quickly sense the error characteristics of the altitude channel to improve the accuracy of the FOG-SINS inertial navigation equipment in altitude velocity and altitude. Summary of the Invention

[0006] The technical problem to be solved by this invention is: by using altitude and celestial velocity as external input reference quantities, this invention estimates the zero bias of the celestial accelerometer in real time and feeds it back to the instrument information, thereby solving the tracking accuracy problem on the celestial channel of the FOG-SINS inertial navigation device.

[0007] The objective of this invention is achieved through the following technical solutions:

[0008] A method for correcting accelerometer zero bias and upward channel damping based on FOG-SINS includes the following steps:

[0009] The satellite navigation system obtains its azimuth velocity and altitude information through a communication interface.

[0010] Using the satellite's celestial velocity as a reference, estimate the zero bias of the celestial accelerometer;

[0011] Using satellite navigation system's azimuth velocity and altitude information as reference values, and the sensitive azimuth force information of the FOG-SINS inertial navigation device as input values, a damping loop is established to calculate the carrier's azimuth velocity and altitude.

[0012] In one embodiment of the present invention, the communication interface adopts any one of RS232 serial port, RS422 serial port, RS485 serial port, 1553B communication interface, Flexray bus, parallel bus interface, CAN interface and Ethernet interface.

[0013] In one embodiment of the present invention, the celestial velocity of the carrier is the vertical velocity information of the carrier in a geographic coordinate system (northeast-sky).

[0014] In one embodiment of the present invention, the carrier height is the carrier altitude information in a geographic coordinate system (northeast sky).

[0015] In one embodiment of the present invention, the zero bias of the accelerometer is the residual zero bias caused by environmental or calibration deviations after the instrument has been calibrated and compensated.

[0016] In one embodiment of the present invention, the accelerometer type is a quartz accelerometer.

[0017] A computer-readable storage medium having stored thereon computer program instructions, which, when loaded and run by a processor, cause the processor to perform the above-described upward channel damping method.

[0018] A computer program product stored on a non-transitory computer-readable medium, the computer program product comprising program code for implementing the above-described upward channel damping method.

[0019] An electronic device, comprising:

[0020] Processor; and

[0021] Memory is used to store computer program instructions;

[0022] When the computer program instructions are loaded and run by the processor, the processor executes the above-described upward channel damping method.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] This invention establishes a new model that uses satellite altitude and celestial velocity as external reference quantities to estimate the zero-bias error of the celestial accelerometer. The corrected celestial specific force information is then fed into the damping feedback loop, accelerating the convergence speed of the celestial velocity and altitude error estimates in the loop. This improves the celestial channel tracking accuracy of the FOG-SINS inertial navigation device and solves the problem of poor celestial channel tracking accuracy and low measurement accuracy during carrier motion caused by the original celestial channel damping model, which only uses altitude as the main reference quantity and does not correct for celestial specific force error. Attached Figure Description

[0025] Figure 1 An integral loop diagram is established using the satellite's celestial velocity information as a reference and the inertial loop's celestial velocity.

[0026] Figure 2 This is the damping circuit diagram for the skyward channel.

[0027] Figure 3 The celestial velocity and altitude curves of the carrier during its movement, as received by the satellite.

[0028] Figure 4 This is the zero bias of the astronomical accelerometer estimated after model calculation.

[0029] Figure 5 A comparison chart of the carrier's azimuth velocity and altitude output by the FOG-SINS inertial navigation device with the azimuth information input by the satellite navigation system.

[0030] Figure 6 This is a diagram showing the processing results of the original upward channel damping model. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0032] A method for correcting accelerometer zero bias and upward channel damping based on FOG-SINS includes:

[0033] (1) Obtain the celestial velocity and altitude information of the satellite navigation system through the communication interface. The communication interface can be any one of the following: RS232 serial port, RS422 serial port, RS485 serial port, 1553B communication interface, Flexray bus, parallel bus interface, CAN interface, and Ethernet interface. The celestial velocity and altitude information of the satellite navigation system refer to the celestial velocity information and altitude information of the carrier under the motion conditions in the local geographic coordinate system (northeast sky) after the satellite navigation receiver is fixedly connected to the carrier.

[0034] (2) Using the satellite's input celestial velocity as a reference, estimate the zero bias of the celestial accelerometer.

[0035] Using the satellite's astronautical velocity information as a reference, an integral loop is established between the satellite's astronautical velocity and the inertial loop's astronautical velocity, such as... Figure 1 As shown.

[0036] The integral loop relation is:

[0037]

[0038] In the formula,

[0039] f z0 —This is the zero-point estimate for the astronomical accelerometer;

[0040] K3—Integral loop coefficient;

[0041] V z —Inertial loop upward velocity;

[0042] V zr —Satellite guiding speed;

[0043] (3) Using the satellite navigation input celestial velocity and high-speed information as reference quantities and celestial force information as input quantities, a damping circuit is established to calculate the celestial velocity and altitude of the carrier.

[0044] The reason for the divergence of the inertial loop skyward channel is that the system is undamped, which causes the system to have positive characteristic roots. Therefore, the satellite guide skyward velocity and altitude are introduced to make the inertial skyward channel damped.

[0045] Establish the upward channel damping circuit, as shown in Figure 2.

[0046] The damping loop relationship is:

[0047] sA ez =f z -f z0 -a z -g-K2(V z -V zr )

[0048] sV ez =A ez -K1(V z -V zr )

[0049] sH=V ez -K0(HH r )

[0050] In the formula,

[0051] f z —Original celestial force comparison;

[0052] a z —Harmful acceleration;

[0053] g—normal gravity;

[0054] A ez —The acceleration of the carrier's upward motion;

[0055] K0—Integral loop coefficient;

[0056] K1, K2 — Damping loop coefficients;

[0057] H—Carrier height;

[0058] V ez —Carrier celestial velocity;

[0059] H r —Guidance altitude;

[0060] s—Laplace operator.

[0061] Example:

[0062] The application of the method of the present invention will be explained using data from a mountain road test of a FOG-SINS inertial navigation device as an example.

[0063] (1) Connect the RS422 communication interface between the FOG-SINS inertial navigation device and the satellite navigation information. Parse according to the established satellite navigation protocol to obtain the azimuth velocity and altitude information. The azimuth velocity and altitude curves received by the satellite navigation system during the carrier's motion are shown below. Figure 3 As shown.

[0064] (2) Using the satellite's input celestial velocity as a reference, estimate the celestial accelerometer zero bias. According to the model in specific implementation method (2), the input quantity V... z For the inertial loop upward velocity, the reference quantity V zr For the satellite's axial velocity, K3 = 0.003. To verify the accuracy of the zero-bias estimation of this model, a zero-point deviation of 0.5 mg was set on the axial accelerometer before data processing. After solving according to the model, the estimated zero-bias f of the axial accelerometer was obtained. z0 like Figure 4 As shown, it is basically consistent with the zero-position deviation of the binding.

[0065] (3) Using the satellite's input axial velocity and high-speed information as reference quantities and axial force information as input quantities, a damping loop is established to calculate the carrier's axial velocity and altitude. According to the model in specific implementation method (3), the input quantity V... z For the inertial loop upward velocity, the reference quantity V zr The satellite's azimuth velocity is given by the input quantity H, which is the inertial loop height, and the reference quantity H is given by the reference quantity H. r For satellite guidance altitude, input quantity f zThe original celestial force ratio, the intermediate calculations include: harmful acceleration a z Normal gravity g, and the acceleration of the carrier in the axial direction A. ez K0 = 0.5, K1 = 0.2, K2 = 0.05. After solving according to this model, the carrier's azimuth velocity and altitude output by the FOG-SINS inertial navigation device are compared with the satellite navigation input azimuth information as follows: Figure 5 As shown (the blue curve represents the satellite navigation sky direction information, and the red curve represents the sky direction channel information output by FOG-SINS), the output of the FOG-SINS sky direction channel can track the reference value very well, and the error converges quickly.

[0066] The processing results of the existing FOG-SINS axial channel damping old model are as follows: Figure 6 As shown (the blue curve represents the satellite navigation information, and the red curve represents the FOG-SINS output astronomical channel information), due to the lack of compensation for the zero bias error of the astronomical accelerometer, there is a fixed deviation in both astronomical velocity and altitude.

[0067] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0068] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for correcting accelerometer zero bias and upward channel damping based on FOG-SINS, characterized in that, include: Obtain the satellite's celestial velocity and altitude information; Using the satellite's celestial velocity as a reference, estimate the zero bias of the celestial accelerometer; Using satellite navigation system's astronautical velocity and altitude information as reference values, and the sensitive astronautical force information of the FOG-SINS inertial navigation device as input values, a damping loop is established to calculate the carrier's astronautical velocity and altitude. The damping loop relationship is: In the formula, —Original celestial force comparison; —This is the zero-point estimate for the astronomical accelerometer; —Harmful acceleration; —Normal gravity; —The acceleration of the carrier's upward motion; —Integral loop coefficients; —Damping loop coefficient; —Inertial loop upward velocity; —Satellite guiding speed; —Carrier height; —Carrier celestial velocity; —Guidance altitude; s—Laplace operator.

2. The upward channel damping method according to claim 1, characterized in that, The satellite's azimuth speed and altitude information can be obtained through any of the following communication interfaces: RS232 serial port, RS422 serial port, RS485 serial port, 1553B communication interface, Flexray bus, parallel bus interface, CAN interface, and Ethernet interface.

3. The upward channel damping method according to claim 1, characterized in that, By establishing an integral loop, the zero bias of the astronomical accelerometer can be estimated. The integral circuit is: In the formula, —Integral loop coefficients.

4. The upward channel damping method according to claim 1, characterized in that, The celestial velocity of the carrier is the vertical velocity information of the carrier in the geographic coordinate system.

5. The upward channel damping method according to claim 1, characterized in that, The carrier height refers to the carrier's altitude information in the geographic coordinate system.

6. The upward channel damping method according to claim 1, characterized in that, The accelerometer type is a quartz accelerometer.

7. A computer-readable storage medium having stored thereon computer program instructions, which, when loaded and run by a processor, cause the processor to perform the method as described in any one of claims 1 to 6.

8. A computer program product stored on a non-transitory computer-readable medium, the computer program product comprising program code for performing the method as described in any one of claims 1 to 6.

9. An electronic device, comprising: processor; as well as Memory is used to store computer program instructions; When the computer program instructions are loaded and run by the processor, the processor performs the method as described in any one of claims 1 to 6.

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