CN101393028B - Rapid estimating and compensating system with IMU mounting angle obliquely set - Google Patents

Abstract

The invention discloses a system for quickly estimating and compensating a tilting IMU setting angle in a micro inertia strapdown navigation attitude system. In the system, a quick estimation and compensation system with multi coordinate conversion mode is adopted to process IMU information generated when the IMU is slantwise arranged; the tilting IMU information processing comprises a sensor information acquisition unit(1), a sensor noise reduction processing unit(2), a setting angle estimation unit(3) and a sensor setting angle compensation unit (4). The system utilizes the coordinate conversion principle among an IMU coordinate system, an aircraft axes and a navigation coordinate system, and adopts the three-shaft acceleration information f2 and the three-shaft spinning top informationOmega 2 outputted by the IMU and initial magnetic course information Phi provided by a magnetic compass to realize the correct estimation of the tilting setting angle; by utilizing the estimated setting angle, the sensor information in flight is compensated in real time, thereby improving the navigation attitude precision of a micro inertia strapdown navigation attitude system.

Description

The Fast estimation of tilting IMU established angle and bucking-out system

Technical field

The present invention relates to a kind ofly in the little inertia strapdown attitude system, the established angle of tilting inertial measurement cluster (IMU) adopts the Fast estimation and the bucking-out system of multi-coordinate translative mode.

Background technology

To navigate in real time appearance information accurately and body is carried out corresponding control be the key that realizes aircraft safety flight for aircraft provides.Determine at present in numerous modes of boat appearance information, inertia boat appearance system becomes the main flow of boat appearance system development with stronger independence, round-the-clock and antijamming capability, particularly along with the development of micro-inertia sensor technology, little inertia strapdown attitude system can be good at satisfying the requirement of user to the miniaturization of boat appearance system, low cost, low-power consumption, becomes the focus of current research.In little inertia strapdown attitude system, the boat appearance precision of system is except outside the Pass having with inertia assembly precision, and is also closely related with the mounting means of inertial measurement cluster.

Present inertial measurement cluster (Inertial Measurement Unit, IMU) mounting means aboard generally has: will comprise that mounting means 1) the strapdown attitude system level of IMU is installed in the center of gravity place of body, and need be controlled in the strict installation accuracy scope, the boat appearance information of boat appearance system realizes the appearance result's of aircraft instrument panel Shanghai Airways, Ltd. real-time demonstration by the mode that connects up in the machine; Mounting means 2) the strapdown attitude system that will comprise IMU shows boat appearance result in real time with required arbitrarily angled being directly installed on the aircraft instrument panel.IMU coordinate system in " mounting means 1) " overlaps with body axis system, therefore can avoid of the influence of tilting established angle to the strapdown attitude system accuracy, but installation accuracy had very high requirement, generally the alignment error angle need be controlled in 1 jiao of branch scope, in addition, because display device apart from each other in machine of boat appearance system and instrument panel, mainly realize the transmission of information between the two by the mode that connects up in the machine, therefore increase the cost and the complicacy of system design, reduced the reliability and the real-time of system." the mounting means 2) " appearance of will navigating system and instrument panel are integrated and design, avoided complicated wiring process, reduced system cost, improved the reliability of system, being convenient to the pilot controls in real time to boat appearance system, there is certain established angle in " but mounting means 2) ", cause the IMU coordinate system no longer to overlap with body axis system, the Fast estimation of the employing multi-coordinate translative mode that proposes by the present invention can realize estimating in real time and compensation fast of tilting IMU established angle effectively with bucking-out system, thereby reduces established angle to the navigate influence of appearance precision of system.

Summary of the invention

In order to solve in the little inertia strapdown attitude system tilting IMU established angle to the influence of boat appearance system accuracy, the present invention proposes a kind of being applicable in the little inertia strapdown attitude system, the Fast estimation of tilting IMU established angle and bucking-out system, utilize the principle of coordinate transformation between IMU coordinate system, body axis system and the navigation coordinate system, adopt the 3-axis acceleration information f of IMU output ₂, three spools gyro information ω ₂And the initial magnetic heading information that provides of magnetic compass

, realize the accurate estimation of tilting established angle, utilize the established angle estimate that sensor information in the flight course is carried out real-Time Compensation, thereby improve the boat appearance precision of little inertia strapdown attitude system.

In a kind of little inertia strapdown attitude of the present invention system, the IMU information that the Fast estimation of tilting IMU established angle and bucking-out system, this system have produced when having adopted the Fast estimation of multi-coordinate translative mode and bucking-out system to tilting placement IMU is handled; Described tilting IMU information processing includes sensor information collecting unit (1), sensor denoising Processing unit (2), established angle estimation unit (3), sensor established angle compensating unit (4);

Sensor information collecting unit (1) is to the acceleration information f of tilting IMU output ₀With angular velocity information ω ₀Gather with analog-to-digital conversion process after, output digital acceleration information f ₁With digital angular velocity information ω ₁

The digital acceleration information f of sensor denoising Processing unit (2) to receiving ₁With digital angular velocity information ω ₁Adopt threshold value qualification method to carry out open country point and reject acquisition nothing wild some acceleration information and angular velocity information, adopt IIR low-pass filtering method to carry out the noise reduction smoothing processing to having wild some acceleration information and angular velocity information then, the noise reduction acceleration information f behind the high frequency noise is eliminated in acquisition ₂With angular velocity information ω ₂, and with f ₂, ω ₂Export to established angle estimation unit (3);

The noise reduction acceleration information f that established angle estimation unit (3) utilization receives ₂, at first according to attitude relational expression G _AttCan obtain navigation coordinate is OX _nY _nZ _nWith IMU coordinate system OX _ImuY _ImuZ _ImuBetween pitching angle theta _NimuWith roll angle γ _Nimu, and to utilize magnetic compass can obtain navigation coordinate be OX _nY _nZ _nWith IMU coordinate system OX _ImuY _ImuZ _ImuBetween the magnetic heading angle

Then, utilize pitching angle theta _Nimu, roll angle γ _NimuWith the magnetic heading angle

, can obtain navigation coordinate according to principle of coordinate transformation is OX _nY _nZ _nWith IMU coordinate system OX _ImuY _ImuZ _ImuBetween navigation → IMU transformation matrix of coordinates

Then, utilize body stationary water 0 degree attitude angle and magnetic heading angle at ordinary times

, can obtain body axis system OX according to principle of coordinate transformation _bY _bZ _bWith navigation coordinate be OX _nY _nZ _nBetween body → navigation coordinate transformation matrix

At last, utilize two transformation matrix of coordinates being asked

With

Can obtain IMU coordinate system OX according to principle of coordinate transformation _ImuY _ImuZ _ImuWith body axis system OX _bY _bZ _bBetween IMU → body transformation matrix of coordinates

Sensor established angle compensating unit (4) receives the IMU coordinate system of established angle estimation unit (3) transmission and the transformation matrix of coordinates between the body axis system

And utilize this transformation matrix according to established angle compensation relationship formula G _CompThe acceleration information and the angular velocity information of IMU output under the IMU coordinate system are transformed into body system down, thereby are convenient to find the solution boat appearance parameter after this.

The Fast estimation of described tilting IMU established angle and bucking-out system, its IMU coordinate system are defined as the lower-left, back, and body axis system is defined as the lower-left, back, and navigation coordinate system is defined as the sky, northeast.

Of the present inventionly be applicable in the little inertia strapdown attitude system, the Fast estimation of tilting IMU established angle and the advantage of bucking-out system be:

(1) utilized the output of IMU self-sensor device to realize the accurate estimation of established angle fast;

(2) allow to install under any established angle of IMU in body, reduced the spent cost of little inertia strapdown attitude system's installation process;

(3) the boat appearance system based on the method design can be directly installed on the instrument panel, is convenient to observation and the control of pilot to flight status, and has simplified the wire laying mode with the display device communication;

(4) Fast estimation of established angle and compensation method rely on software programming to realize fully, it is embedded on the boat appearance computing machine plate in the little inertia strapdown attitude system, hardware design there is not a bit additional requirement, the modular design of program code has reduced taking of processor memory space, and has portable preferably;

(5) to estimating that good established angle has the outage memory function, has guaranteed the safe flight of the whole process of little inertia strapdown attitude system.

Description of drawings

Fig. 1 is the assembling synoptic diagram of little inertia strapdown attitude system and aircraft front end.

Fig. 2 is the Fast estimation of IMU established angle of the present invention and the Processing Structure block diagram of compensation.

Fig. 3 A is the coordinate conversion synoptic diagram between navigation coordinate system and the IMU coordinate system.

Fig. 3 B is the coordinate conversion synoptic diagram between navigation coordinate system and the body axis system.

Fig. 4 is the figure as a result that takes a flight test of the tilting strapdown attitude system that comprises IMU.

Embodiment

The present invention is described in further detail below in conjunction with drawings and Examples.

Referring to shown in Figure 1, the present invention is that the Fast estimation of tilting IMU established angle and bucking-out system shown in the figure, are provided with pilot seat, flight control bar, instrument panel etc. in a kind of little inertia strapdown attitude system in the cabin of aircraft front end.In order to improve the influence that distance causes between the display device on boat appearance system and the instrument panel, the inventor is installed in little inertia strapdown attitude system the back of instrument panel with certain angle (established angle), tilting placement IMU can cause gyro, add the reduction of meter accuracy, has a strong impact on boat appearance result.The IMU information that has produced when therefore, the inventor has adopted the Fast estimation of multi-coordinate translative mode and bucking-out system to tilting placement IMU is handled.In the present invention, include inertial measurement cluster (IMU) in the little inertia strapdown attitude system.

Referring to shown in Figure 2, the present invention includes tilting IMU information processing: sensor information collecting unit 1, sensor denoising Processing unit 2, established angle estimation unit 3, sensor established angle compensating unit 4;

The acceleration information f of 1 pair of tilting IMU output of sensor information collecting unit ₀With angular velocity information ω ₀Gather with analog-to-digital conversion process after, output digital acceleration information f ₁With digital angular velocity information ω ₁

The digital acceleration information f of the 2 pairs of receptions in sensor denoising Processing unit ₁With digital angular velocity information ω ₁Adopt threshold value qualification method to carry out open country point and reject acquisition nothing wild some acceleration information and angular velocity information, adopt IIR low-pass filtering method to carry out the noise reduction smoothing processing to having wild some acceleration information and angular velocity information then, the noise reduction acceleration information f behind the high frequency noise is eliminated in acquisition ₂With angular velocity information ω ₂, and with f ₂, ω ₂Export to established angle estimation unit 3;

In the present invention, described threshold value qualification method goes wild point to be meant the current output valve of IMU accelerometer

With threshold epsilon _AccRelatively, if current time accelerometer output valve

Absolute value greater than ε _Acc, then use the output of previous moment accelerometer Degree of adding meter output as current time

, ε wherein _AccValue is 20g (g represents a gravity field unit); The current output valve of IMU gyro

With threshold epsilon _GyroRelatively, if current time gyro output valve

Absolute value greater than ε _Gyro, then use the output of previous moment gyro

Gyro output as current time

, ε wherein _GyroValue is 200 °/s.

Established angle estimation unit 3 utilizes the noise reduction acceleration information f that receives ₂, at first according to attitude relational expression G _AttCan obtain navigation coordinate is OX _nY _nZ _nWith IMU coordinate system OX _ImuY _ImuZ _ImuBetween pitching angle theta _NimuWith roll angle γ _Nimu, and to utilize magnetic compass can obtain navigation coordinate be OX _nY _nZ _nWith IMU coordinate system OX _ImuY _ImuZ _ImuBetween the magnetic heading angle

Then, utilize pitching angle theta _Nimu, roll angle γ _NimuWith the magnetic heading angle

, can obtain navigation coordinate according to principle of coordinate transformation is OX _nY _nZ _nWith IMU coordinate system OX _ImuY _ImuZ _ImuBetween navigation → IMU transformation matrix of coordinates

Then, utilize body stationary water 0 degree attitude angle and magnetic heading angle at ordinary times

, can obtain body axis system OX according to principle of coordinate transformation _bY _bZ _bWith navigation coordinate be OX _nY _nZ _nBetween body → navigation coordinate transformation matrix

At last, utilize two transformation matrix of coordinates being asked

With

, can obtain IMU coordinate system OX according to principle of coordinate transformation _ImuY _ImuZ _ImuWith body axis system OX _bY _bZ _bBetween IMU → body transformation matrix of coordinates

In the present invention, shown in Fig. 3 A, Fig. 3 B, pitching angle theta _NimuBe meant around coordinate system OX ₁Y ₁Z _nY ₁Axle rotates to coordinate system OX ₂Y ₁Z ₂Angle.Roll angle γ _NimuBe meant around coordinate system OX ₂Y ₁Z ₂X ₂Axle rotates to coordinate system OX _ImuY _ImuZ _ImuAngle.The magnetic heading angle

Can be meant that around navigation coordinate be OX _nY _nZ _nZ _nAxle rotates to coordinate system OX ₁Y ₁Z _nAngle (Fig. 3 A), can be meant that also around navigation coordinate be OX _nY _nZ _nZ _nAxle rotates to body axis system OX _bY _bZ _bAngle (Fig. 3 B), be the output of magnetic compass.In the present invention, the IMU coordinate system is defined as the lower-left, back, and body axis system is defined as the lower-left, back, and navigation coordinate system is defined as the sky, northeast.

In the present invention, attitude relational expression $G_{\mathrm{att}}=\left\{\begin{array}{c}{\mathrm{\θ}}_{\mathrm{nimu}}=a\sin \left(f_{\mathrm{ximu}}\right)\\ {\mathrm{\γ}}_{\mathrm{nimu}}=-a\tan (f_{\mathrm{yimu}}/f_{\mathrm{zimu}})\end{array}\right.,$ In the formula, f _XimuThe filtering output value of X-axis accelerometer among the expression IMU, f _YimuThe filtering output value of Y-axis accelerometer among the expression IMU, f _ZimuThe filtering output value of Z axis accelerometer among the expression IMU.

In the present invention, navigation → IMU transformation matrix of coordinates

In the present invention, body → navigation coordinate transformation matrix

In the present invention, IMU → body transformation matrix of coordinates $C_{\mathrm{imu}}^b={\left(C_n^{\mathrm{imu}}{C}_b^n\right)}^T,$ The transposition of T denotation coordination transformation matrix.

Sensor established angle compensating unit 4 receives the IMU coordinate system of established angle estimation unit 3 transmission and the transformation matrix of coordinates between the body axis system

And utilize this transformation matrix according to established angle compensation relationship formula G _CompThe acceleration information and the angular velocity information of IMU output under the IMU coordinate system are transformed into body system down, thereby are convenient to find the solution boat appearance parameter after this.

In the present invention, established angle compensation relationship formula $G_{\mathrm{comp}}=\left\{\begin{array}{c}\left[\begin{array}{c}{f}_{\mathrm{bx}}\\ f_{\mathrm{by}}\\ f_{\mathrm{bz}}\end{array}\right]=\left[\begin{array}{c}{f}_{\mathrm{ximu}}\\ f_{\mathrm{yimu}}\\ f_{\mathrm{zimu}}\end{array}\right]C_{\mathrm{imu}}^b\\ \left[\begin{array}{c}{\mathrm{\ω}}_{\mathrm{bx}}\\ {\mathrm{\ω}}_{\mathrm{by}}\\ {\mathrm{\ω}}_{\mathrm{bz}}\end{array}\right]=\left[\begin{array}{c}{\mathrm{\ω}}_{\mathrm{ximu}}\\ {\mathrm{\ω}}_{\mathrm{yimu}}\\ {\mathrm{\ω}}_{\mathrm{zimu}}\end{array}\right]C_{\mathrm{imu}}^b\end{array}\right.,$ In the formula, f _BxOutput valve after the coordinate transform of expression X-axis accelerometer under the body system, f _ByOutput valve after the coordinate transform of expression Y-axis accelerometer under the body system, f _BzOutput valve after the coordinate transform of expression Z axis accelerometer under the body system, ω _BxOutput valve after the coordinate transform of expression X-axis gyro under the body system, ω _ByOutput valve after the coordinate transform of expression Y-axis gyro under the body system, ω _BzOutput valve after the coordinate transform of expression Z axle gyro under the body system.

In the little inertia strapdown attitude of the present invention system, the Fast estimation of tilting IMU established angle and bucking-out system, it includes following estimation and compensation deals step:

The first step: by the acceleration information f of tilting IMU output in the little inertia strapdown attitude of the sensor information collecting unit 1 collection system ₀With angular velocity information ω ₀, obtain the digital acceleration information f through analog to digital conversion ₁With digital angular velocity information ω ₁

Second step: the digital acceleration information f that in sensor denoising Processing unit 2, collection is obtained ₁With digital angular velocity information ω ₁Utilize threshold value qualification method to carry out open country point and reject, utilize IIR low-pass filtering method to carry out level and smooth denoising Processing then, thereby obtain not have wild point and level and smooth noise reduction acceleration information f ₂With angular velocity information ω ₂

The 3rd step: utilize the accelerometer output valve f under the IMU coordinate system behind the level and smooth noise reduction _Ximu, f _Yimu, f _ZimuObtain pitching angle theta _NimuWith roll angle γ _Nimu

The 4th step: utilize the 3rd to go on foot the pitching angle theta that obtains _Nimu, roll angle γ _NimuThe magnetic heading angle that provides with magnetic compass

Obtain the navigation → IMU transformation matrix of coordinates between navigation coordinate system and IMU coordinate system

The 5th step: the magnetic heading angle that degree attitude angle of 0 when utilizing level and magnetic compass provide

Obtain the body → navigation coordinate transformation matrix between body axis system and navigation coordinate system

The 6th step: two transformation matrix of coordinates that utilize the 4th step and the 5th step to obtain can obtain the IMU → body transformation matrix of coordinates between IMU coordinate system and the body axis system

The 7th step: utilize the 6th to go on foot the IMU → body transformation matrix of coordinates that obtains

The sensor output of IMU is transformed under the body axis system, so that navigation calculation after this.

Embodiment 1:

To include the Fast estimation of the tilting IMU established angle of the present invention and the micromechanics strapdown attitude system of bucking-out system and be fixedly mounted on the instrument panel back in the tilting 20 established angle modes of spending.If body is when high-altitude 1000m, speed 300km/h fly, the flight situation of the angle of pitch, roll angle, course angle as shown in Figure 4 in the body flight course that collects successively, obtain from the analysis of flight situation, the body flight precision after the present invention estimates and compensates is in ± 2 degree scopes.

Embodiment 2:

To include the Fast estimation of the tilting IMU established angle of the present invention and the micromechanics strapdown attitude system of bucking-out system and be fixedly mounted on the instrument panel back in the tilting 45 established angle modes of spending.If body is when high-altitude 1000m, speed 200km/h fly, the flight situation of the angle of pitch, roll angle, course angle in the body flight course that collects successively, obtain from the analysis of flight situation, the body flight precision after the present invention estimates and compensates is in ± 2.55 degree scopes.

By the result's that takes a flight test analysis, a kind of being applicable in the micromechanics strapdown attitude system that the present invention proposes, the real-time estimation and the bucking-out system of tilting IMU established angle can be with the arbitrarily angled optional positions that is installed in the instrument panel back.

The IMU Installation Modes that the present invention proposes utilizes the sensor output of IMU under the IMU coordinate system, and the transformation relation between IMU coordinate system, body axis system and the navigation coordinate system, finish real-time estimation to tilting IMU established angle, and to tilting IMU sensor output the carrying out compensation of established angle, thereby make that the strapdown attitude system can be with required arbitrarily angled directly installation in body, reduce system cost, improved the reliability of system.

Claims (3)

1. the Fast estimation and the bucking-out system of tilting IMU established angle in the little inertia strapdown attitude system is characterized in that: the IMU information that has produced when having adopted the Fast estimation of multi-coordinate translative mode and bucking-out system to tilting placement IMU is handled; Described tilting IMU information processing includes sensor information collecting unit (1), sensor denoising Processing unit (2), established angle estimation unit (3), sensor established angle compensating unit (4); Sensor information collecting unit (1) is to the acceleration information f of tilting IMU output ₀With angular velocity information ω ₀Gather with analog-to-digital conversion process after, output digital acceleration information f ₁With digital angular velocity information ω ₁

The digital acceleration information f of sensor denoising Processing unit (2) to receiving ₁With digital angular velocity information ω ₁Adopt threshold value qualification method to carry out open country point and reject acquisition nothing wild some acceleration information and angular velocity information, adopt IIR low-pass filtering method to carry out the noise reduction smoothing processing to having wild some acceleration information and angular velocity information then, the noise reduction acceleration information f behind the high frequency noise is eliminated in acquisition ₂With angular velocity information ω ₂, and respectively with f ₂Export to established angle estimation unit (3), ω ₂Export to sensor established angle compensating unit (4);

The noise reduction acceleration information f that established angle estimation unit (3) utilization receives ₂, at first according to attitude relational expression G _AttCan obtain navigation coordinate is OX _nY _nZ _nWith IMU coordinate system OX _ImuY _ImuZ _ImuBetween pitching angle theta _NimuWith roll angle γ _Nimu, and to utilize magnetic compass can obtain navigation coordinate be OX _nY _nZ _nWith IMU coordinate system OX _ImuY _ImuZ _ImuBetween the magnetic heading angle

Then, utilize pitching angle theta _Nimu, roll angle γ _NimuWith the magnetic heading angle

, can obtain navigation coordinate according to principle of coordinate transformation is OX _nY _nZ _nWith IMU coordinate system OX _ImuY _ImuZ _ImuBetween navigation → IMU transformation matrix of coordinates C _n ^Imu

Then, utilize body stationary water 0 degree attitude angle and magnetic heading angle at ordinary times

, can obtain body axis system OX according to principle of coordinate transformation _bY _bZ _bWith navigation coordinate be OX _nY _nZ _nBetween body → navigation coordinate transformation matrix C _b ⁿ

At last, utilize two transformation matrix of coordinates C that asked _n ^ImuAnd C _b ⁿ, can obtain IMU coordinate system OX according to principle of coordinate transformation _ImuY _ImuZ _ImuWith body axis system OX _bY _bZ _bBetween IMU → body transformation matrix of coordinates C _Imu ^b

Described attitude relational expression

In the formula, f _XimuThe filtering output value of X-axis accelerometer among the expression IMU, f _YimuThe filtering output value of Y-axis accelerometer among the expression IMU, f _ZimuThe filtering output value of Z axis accelerometer among the expression IMU;

Described navigation → IMU transformation matrix of coordinates

Described body → navigation coordinate transformation matrix

Described IMU → body transformation matrix of coordinates

The transposition of T denotation coordination transformation matrix;

Sensor established angle compensating unit (4) receives the IMU coordinate system of established angle estimation unit (3) transmission and the transformation matrix of coordinates C between the body axis system _Imu ^b, and utilize this transformation matrix according to established angle compensation relationship formula G _CompThe acceleration information and the angular velocity information of IMU output under the IMU coordinate system are transformed into body system down, thereby are convenient to find the solution boat appearance parameter after this;

Described established angle compensation relationship formula

In the formula, f _BxOutput valve after the coordinate transform of expression X-axis accelerometer under the body system, f _ByOutput valve after the coordinate transform of expression Y-axis accelerometer under the body system, f _BzOutput valve after the coordinate transform of expression Z axis accelerometer under the body system, ω _BxOutput valve after the coordinate transform of expression X-axis gyro under the body system, ω _ByOutput valve after the coordinate transform of expression Y-axis gyro under the body system, ω _BzOutput valve after the coordinate transform of expression z axle gyro under the body system.

2. the Fast estimation of tilting IMU established angle according to claim 1 and bucking-out system is characterized in that: described threshold value qualification method is carried out wild point and is rejected the current output valve f that is meant the IMU accelerometer ₁ ^kWith threshold epsilon _AccRelatively, if current time accelerometer output valve f ₁ ^kAbsolute value greater than ε _Acc, then use the output f of previous moment accelerometer ₁ ^K-1Accelerometer output f as current time ₁ ^k, ε wherein _AccValue is 20g; The current output valve ω of IMU gyro ₁ ^kWith threshold epsilon _GyroRelatively, if current time gyro output valve ω ₁ ^kAbsolute value greater than ε _Gyro, then use the output ω of previous moment gyro ₁ ^K-1Gyro output ω as current time ₁ ^k, ε wherein _GyroValue is 200 °/s.

3. the Fast estimation of tilting IMU established angle according to claim 1 and bucking-out system is characterized in that: the IMU coordinate system is defined as the lower-left, back, and body axis system is defined as the lower-left, back, and navigation coordinate system is defined as the sky, northeast.

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