CN105403218A - Geomagnetism correction method for pitch angle of quad-rotor unmanned helicopter - Google Patents

Abstract

The invention provides a geomagnetism correction method for the pitch angle of a quad-rotor unmanned helicopter. The method comprises the steps of building a helicopter body coordinate system and a navigation coordinate system; controlling the quad-rotor unmanned helicopter for rotating at the preset flight attitude angle according to the helicopter body coordinate system and the navigation coordinate system; building a rotating matrix according to the flight attitude angle of rotation of the helicopter body, and calculating the helicopter attitude matrix of the quad-rotor unmanned helicopter according to the rotating matrix; setting the projection of geomagnetism in a reference system, and calculating the geomagnetism pitch angle correction value according to the projection of the geomagnetism in the reference system, the rotating matrix and the flight attitude matrix; correcting the pitch angle of the quad-rotor unmanned helicopter according to the geomagnetism pitch angle correction value so as to compensate for attitude errors caused when a gyroscope of the quad-rotor unmanned helicopter is drifted. On the premise that the product cost is not increased, the attitude errors are compensated for, and the precision is improved.

Description

For the earth magnetism modification method of the angle of pitch of four rotor wing unmanned aerial vehicles

Technical field

The present invention relates to unmanned air vehicle technique field, particularly a kind of earth magnetism modification method of the angle of pitch for four rotor wing unmanned aerial vehicles.

Background technology

The robot pilot that four rotor wing unmanned aerial vehicles use compares low side, and its product price is lower.The basis that robot pilot can realize automatically controlling is attitude measurement, and the basis of attitude measurement is gyroscope.But the gyroscope that four rotor wing unmanned aerial vehicles use limits due to cost, and precision is not high, adds the drift of gyroscope itself, can to attitude generation considerable influence after long-term accumulated.

Summary of the invention

Object of the present invention is intended at least solve one of described technological deficiency.

For this reason, the object of the invention is to the earth magnetism modification method proposing a kind of angle of pitch for four rotor wing unmanned aerial vehicles, under the prerequisite not improving cost of products, achieve the compensation to attitude error, improve precision.

To achieve these goals, embodiments of the invention provide a kind of earth magnetism modification method of the angle of pitch for four rotor wing unmanned aerial vehicles, comprise the steps:

Step S1, sets up body axis system and navigational coordinate system;

Step S2, controls described four rotor wing unmanned aerial vehicles and rotates with pre-set flight attitude angle according to described body axis system and navigational coordinate system;

Step S3, sets up rotation matrix according to the flight attitude angle that described body rotates, and calculates the aspect matrix of described four rotor wing unmanned aerial vehicles according to described rotation matrix;

Step S4, arranges the projection of earth magnetism in reference frame, according to the projection of described earth magnetism in reference frame, rotation matrix and flight attitude matrix computations earth magnetism angle of pitch modified value;

Step S5, the attitude error that the angle of pitch of four rotor wing unmanned aerial vehicles causes with the gyroscopic drift compensating described four rotor wing unmanned aerial vehicles according to the correction of described earth magnetism angle of pitch modified value.

Further, described body axis system is defined as: X-axis represents roll axle, and Y-axis represents pitch axis, and Z axis represents course; Described navigational coordinate system is defined as east northeast ground coordinate system.

Further, in described step S2, described flight attitude angle is the angle of body when rotating in the following order: the angle ψ rotated around described Z axis, around the angle θ that described Y-axis is rotated, around the angle Φ that described X-axis is rotated.

Further, in described step S3, described rotation matrix is (c1, c2, c3),

Rotate ψ angle according to around z-axis, calculate $c1=\left[\begin{array}{ccc}cos\mathrm{\ψ}& sin\mathrm{\ψ}& 0\\ -sin\mathrm{\ψ}& cos\mathrm{\ψ}& 0\\ 0& 0& 1\end{array}\right];$

Rotate θ angle according to around y-axis, calculate $c2=\left[\begin{array}{ccc}cos\mathrm{\θ}& 0& -sin\mathrm{\θ}\\ 0& 1& 0\\ sin\mathrm{\θ}& 0& \cos \mathrm{\θ}\end{array}\right];$

Rotate Φ angle according to around x-axis, calculate $c3=\left[\begin{array}{ccc}1& 0& 0\\ 0& cos\mathrm{\φ}& \sin \mathrm{\φ}\\ 0& -sin\mathrm{\φ}& cos\mathrm{\φ}\end{array}\right].$

Further, in described step S3, calculate the aspect matrix of described four rotor wing unmanned aerial vehicles according to described rotation matrix, comprise the steps:

Carrier system is changed to reference to system, c according to described rotation matrix _n ^b=c3c2c1;

Then described aspect Matrix C is calculated _b ⁿfor:

$\begin{array}{c}{C}_b^n=\left[\begin{array}{ccc}{c}_{11}& c_{12}& c_{13}\\ c_{21}& c_{22}& c_{23}\\ c_{31}& c_{32}& c_{33}\end{array}\right]=\\ \left[\begin{array}{ccc}\cos \mathrm{\θ}\cos \mathrm{\ψ}& -\cos \mathrm{\Φ}\sin \mathrm{\ψ}+\sin \mathrm{\Φ}\sin \mathrm{\θ}\cos \mathrm{\ψ}& \sin \mathrm{\Φ}\sin \mathrm{\ψ}+\cos \mathrm{\Φ}\sin \mathrm{\θ}\cos \mathrm{\ψ}\\ \cos \mathrm{\θ}\sin \mathrm{\ψ}& \cos \mathrm{\Φ}\cos \mathrm{\ψ}+\sin \mathrm{\Φ}\sin \mathrm{\θ}\sin \mathrm{\ψ}& -\sin \mathrm{\Φ}\cos \mathrm{\ψ}+\cos \mathrm{\Φ}\sin \mathrm{\θ}\sin \mathrm{\ψ}\\ -\sin \mathrm{\θ}& \sin \mathrm{\Φ}\cos \mathrm{\θ}& \cos \mathrm{\Φ}\cos \mathrm{\ψ}\end{array}\right]\end{array}.$

Wherein,

$\mathrm{\Φ}=arctan\[\frac{c_{32}}{c_{33}}\]$

θ＝arcsin[-C ₃₁]

$\mathrm{\ψ}=arctan\[\frac{c_{21}}{c_{11}}\].$

Further, in described step S4, according to the projection of described earth magnetism in reference frame, rotation matrix and flight attitude matrix computations earth magnetism angle of pitch modified value θ d be:

θd＝arcsin(yb/xb)，

Wherein,

$\begin{array}{c}\left[\begin{array}{c}{x}_b\\ y_b\\ z_b\end{array}\right]=c_3{c}_1\left[\begin{array}{c}{x}_b^{11}\\ y_b^{11}\\ z_b^{11}\end{array}\right]=\left[\begin{array}{ccc}1& 0& 0\\ 0& \cos \mathrm{\φ}& \sin \mathrm{\φ}\\ 0& -\sin \mathrm{\φ}& \cos \end{array}\right]\left[\begin{array}{ccc}\cos \mathrm{\ψ}& \sin \mathrm{\ψ}& 0\\ -\sin \mathrm{\ψ}& \cos \mathrm{\ψ}& 0\\ 0& 0& 1\end{array}\right]=\\ \left[\begin{array}{ccc}\cos \mathrm{\ψ}& \sin \mathrm{\ψ}& 0\\ \sin \mathrm{\ψ}\cos \mathrm{\φ}& \cos \mathrm{\ψ}\cos \mathrm{\φ}& \sin \mathrm{\φ}\\ \sin \mathrm{\ψ}\sin \mathrm{\φ}& -\cos \mathrm{\ψ}\sin \mathrm{\φ}& \cos \mathrm{\φ}\end{array}\right]\left[\begin{array}{c}{x}_b^{11}\\ y_b^{11}\\ z_b^{11}\end{array}\right],\end{array}$

Wherein, $\left[\begin{array}{c}{x}_b^{11}\\ y_b^{11}\\ z_b^{11}\end{array}\right]$ For the projection of earth magnetism in reference frame.

Further, the angle of pitch of described four rotor wing unmanned aerial vehicles according to the correction of earth magnetism angle of pitch modified value, comprises the steps:

θ1＝θ _{_1}-k×(θg-θd)，

Wherein, θ 1 is the revised angle of pitch, θ _{_ 1}pitching angle theta 1, the θ g calculated for the last time is that body rotates luffing angle around y-axis, and θ g=(Φ, θ, ψ), k are predetermined coefficient.

Further, the span of k is 0.4 ~ 0.6.

According to the earth magnetism modification method of the angle of pitch for four rotor wing unmanned aerial vehicles of the embodiment of the present invention, by the earth magnetism correction angle of pitch, realize the error to the attitude error that gyroscopic drift causes, based on existing sensor, do not increase extra sensor, thus under the prerequisite not improving cost of products, achieve the compensation to attitude error, improve precision.

The aspect that the present invention adds and advantage will part provide in the following description, and part will become obvious from the following description, or be recognized by practice of the present invention.

Accompanying drawing explanation

Above-mentioned and/or additional aspect of the present invention and advantage will become obvious and easy understand from accompanying drawing below combining to the description of embodiment, wherein:

Fig. 1 is the process flow diagram of the earth magnetism modification method of the angle of pitch for four rotor wing unmanned aerial vehicles according to the embodiment of the present invention.

Embodiment

Be described below in detail embodiments of the invention, the example of described embodiment is shown in the drawings, and wherein same or similar label represents same or similar element or has element that is identical or similar functions from start to finish.Be exemplary below by the embodiment be described with reference to the drawings, be intended to for explaining the present invention, and can not limitation of the present invention be interpreted as.

As shown in Figure 1, the earth magnetism modification method of the angle of pitch for four rotor wing unmanned aerial vehicles of the embodiment of the present invention, comprises the steps:

Step S1, sets up body axis system and navigational coordinate system.

Particularly, establishment of coordinate system is as follows: body axis system is defined as: X-axis represents roll axle, corresponding front; Y-axis represents pitch axis, corresponding right; Z axis represents course, corresponding below.Navigational coordinate system is defined as east northeast ground coordinate system.

Step S2, controls four rotor wing unmanned aerial vehicles and rotates with pre-set flight attitude angle according to body axis system and navigational coordinate system.

Flight attitude angle is the angle of body when rotating in the following order: the angle ψ rotated around Z axis, around the angle θ that Y-axis is rotated, around the angle Φ that X-axis is rotated.

Step S3, sets up rotation matrix according to the flight attitude angle that body rotates, and calculates the aspect matrix of four rotor wing unmanned aerial vehicles according to rotation matrix.

Body rotates and rotates ψ according to deviation from voyage route to axle (Z axis), and pitch axis (Y-axis) rotates θ, and when roll axle (X-axis) rotates the order rotation of Φ, rotation matrix is (c1, c2, c3),

Rotate ψ angle according to around z-axis, calculate $c1=\left[\begin{array}{ccc}cos\mathrm{\ψ}& sin\mathrm{\ψ}& 0\\ -sin\mathrm{\ψ}& cos\mathrm{\ψ}& 0\\ 0& 0& 1\end{array}\right];---\left(1\right)$

Rotate θ angle according to around y-axis, calculate $c2=\left[\begin{array}{ccc}cos\mathrm{\θ}& 0& -sin\mathrm{\θ}\\ 0& 1& 0\\ sin\mathrm{\θ}& 0& \cos \mathrm{\θ}\end{array}\right];---\left(2\right)$

Rotate Φ angle according to around x-axis, calculate $c3=\left[\begin{array}{ccc}1& 0& 0\\ 0& cos\mathrm{\φ}& \sin \mathrm{\φ}\\ 0& -sin\mathrm{\φ}& cos\mathrm{\φ}\end{array}\right];---\left(3\right)$

Based on this, calculate the aspect matrix of four rotor wing unmanned aerial vehicles according to rotation matrix, comprise the steps:

First, be changed to carrier system according to rotation matrix with reference to system,

c _n ^b＝c3c2c1；(4)

Then, aspect Matrix C is calculated _b ⁿfor:

$\begin{array}{c}{C}_b^n=\left[\begin{array}{ccc}{c}_{11}& c_{12}& c_{13}\\ c_{21}& c_{22}& c_{23}\\ c_{31}& c_{32}& c_{33}\end{array}\right]=\\ \left[\begin{array}{ccc}\cos \mathrm{\θ}\cos \mathrm{\ψ}& -\cos \mathrm{\Φ}\sin \mathrm{\ψ}+\sin \mathrm{\Φ}\sin \mathrm{\θ}\cos \mathrm{\ψ}& \sin \mathrm{\Φ}\sin \mathrm{\ψ}+\cos \mathrm{\Φ}\sin \mathrm{\θ}\cos \mathrm{\ψ}\\ \cos \mathrm{\θ}\sin \mathrm{\ψ}& \cos \mathrm{\Φ}\cos \mathrm{\ψ}+\sin \mathrm{\Φ}\sin \mathrm{\θ}\sin \mathrm{\ψ}& -\sin \mathrm{\Φ}\cos \mathrm{\ψ}+\cos \mathrm{\Φ}\sin \mathrm{\θ}\sin \mathrm{\ψ}\\ -\sin \mathrm{\θ}& \sin \mathrm{\Φ}\cos \mathrm{\θ}& \cos \mathrm{\Φ}\cos \mathrm{\ψ}\end{array}\right]\end{array}$

$=\left[\begin{array}{ccc}\left(a^2+b^2-c^2-d^2\right)& 2\left(bc-ad\right)& 2\left(bd+ac\right)\\ 2\left(bc+ad\right)& \left(a^2-b^2+c^2-d^2\right)& 2\left(cd-ab\right)\\ 2\left(bd-ac\right)& 2\left(cd+ab\right)& \left(a^2-b^2-c^2+b^2\right)\end{array}\right],---\left(5\right)$

Further, can be according to above-mentioned aspect matrix computations carriage angle:

$\mathrm{\Φ}=arctan\[\frac{c_{32}}{c_{33}}\]---\left(6\right)$

θ＝arcsin[-C ₃₁](7)

$\mathrm{\ψ}=arctan\[\frac{c_{21}}{c_{11}}\]---\left(8\right)$

Step S4, arranges the projection of earth magnetism in reference frame, according to the projection of earth magnetism in reference frame, rotation matrix and flight attitude matrix computations earth magnetism angle of pitch modified value θ d.

According to the projection of earth magnetism in reference frame, rotation matrix and flight attitude matrix computations earth magnetism angle of pitch modified value θ d.

θd＝arcsin(yb/xb)，

Wherein,

$\begin{array}{c}\left[\begin{array}{c}{x}_b\\ y_b\\ z_b\end{array}\right]=c_3{c}_1\left[\begin{array}{c}{x}_b^{11}\\ y_b^{11}\\ z_b^{11}\end{array}\right]=\left[\begin{array}{ccc}1& 0& 0\\ 0& \cos \mathrm{\φ}& \sin \mathrm{\φ}\\ 0& -\sin \mathrm{\φ}& \cos \end{array}\right]\left[\begin{array}{ccc}\cos \mathrm{\ψ}& \sin \mathrm{\ψ}& 0\\ -\sin \mathrm{\ψ}& \cos \mathrm{\ψ}& 0\\ 0& 0& 1\end{array}\right]=\\ \left[\begin{array}{ccc}\cos \mathrm{\ψ}& \sin \mathrm{\ψ}& 0\\ \sin \mathrm{\ψ}\cos \mathrm{\φ}& \cos \mathrm{\ψ}\cos \mathrm{\φ}& \sin \mathrm{\φ}\\ \sin \mathrm{\ψ}\sin \mathrm{\φ}& -\cos \mathrm{\ψ}\sin \mathrm{\φ}& \cos \mathrm{\φ}\end{array}\right]\left[\begin{array}{c}{x}_b^{11}\\ y_b^{11}\\ z_b^{11}\end{array}\right],\end{array}$

Wherein, $\left[\begin{array}{c}{x}_b^{11}\\ y_b^{11}\\ Z_b^{11}\end{array}\right]$ For the projection of earth magnetism in reference frame.

Step S5, according to the attitude error that the angle of pitch of earth magnetism angle of pitch modified value correction four rotor wing unmanned aerial vehicle causes with the gyroscopic drift compensating four rotor wing unmanned aerial vehicles.

θ1＝θ _{_1}-k×(θg-θd)，

Wherein, θ 1 is the revised angle of pitch, θ _{_ 1}pitching angle theta 1, the θ g calculated for the last time is that body rotates luffing angle around y-axis, and θ g=(Φ, θ, ψ), k are predetermined coefficient.The span of k is 0.4 ~ 0.6.

According to the earth magnetism modification method of the angle of pitch for four rotor wing unmanned aerial vehicles of the embodiment of the present invention, by the earth magnetism correction angle of pitch, realize the error to the attitude error that gyroscopic drift causes, based on existing sensor, do not increase extra sensor, thus under the prerequisite not improving cost of products, achieve the compensation to attitude error, improve precision.

In the description of this instructions, specific features, structure, material or feature that the description of reference term " embodiment ", " some embodiments ", " example ", " concrete example " or " some examples " etc. means to describe in conjunction with this embodiment or example are contained at least one embodiment of the present invention or example.In this manual, identical embodiment or example are not necessarily referred to the schematic representation of above-mentioned term.And the specific features of description, structure, material or feature can combine in an appropriate manner in any one or more embodiment or example.

Although illustrate and describe embodiments of the invention above, be understandable that, above-described embodiment is exemplary, can not be interpreted as limitation of the present invention, those of ordinary skill in the art can change above-described embodiment within the scope of the invention when not departing from principle of the present invention and aim, revising, replacing and modification.Scope of the present invention is by claims extremely equivalency.

Claims (8)

1., for an earth magnetism modification method for the angle of pitch of four rotor wing unmanned aerial vehicles, it is characterized in that, comprise the steps:

Step S1, sets up body axis system and navigational coordinate system;

Step S2, controls described four rotor wing unmanned aerial vehicles and rotates with pre-set flight attitude angle according to described body axis system and navigational coordinate system;

Step S3, sets up rotation matrix according to the flight attitude angle that described body rotates, and calculates the aspect matrix of described four rotor wing unmanned aerial vehicles according to described rotation matrix;

Step S4, arranges the projection of earth magnetism in reference frame, according to the projection of described earth magnetism in reference frame, rotation matrix and flight attitude matrix computations earth magnetism angle of pitch modified value;

Step S5, the attitude error that the angle of pitch of four rotor wing unmanned aerial vehicles causes with the gyroscopic drift compensating described four rotor wing unmanned aerial vehicles according to the correction of described earth magnetism angle of pitch modified value.

2., as claimed in claim 1 for the earth magnetism modification method of the angle of pitch of four rotor wing unmanned aerial vehicles, it is characterized in that, described body axis system is defined as: X-axis represents roll axle, and Y-axis represents pitch axis, and Z axis represents course; Described navigational coordinate system is defined as east northeast ground coordinate system.

3. as claimed in claim 1 for the earth magnetism modification method of the angle of pitch of four rotor wing unmanned aerial vehicles, it is characterized in that, in described step S2, described flight attitude angle is the angle of body when rotating in the following order: the angle ψ rotated around described Z axis, around the angle θ that described Y-axis is rotated, around the angle Φ that described X-axis is rotated.

4., as claimed in claim 1 for the earth magnetism modification method of the angle of pitch of four rotor wing unmanned aerial vehicles, it is characterized in that, in described step S3, described rotation matrix is (c1, c2, c3),

Rotate ψ angle according to around z-axis, calculate $c1=\left[\begin{array}{ccc}\cos \mathrm{\ψ}& \sin \mathrm{\ψ}& 0\\ -\sin \mathrm{\ψ}& \cos \mathrm{\ψ}& 0\\ 0& 0& 1\end{array}\right];$

Rotate θ angle according to around y-axis, calculate $c2=\left[\begin{array}{ccc}cos\mathrm{\θ}& 0& -sin\mathrm{\θ}\\ 0& 1& 0\\ sin\mathrm{\θ}& 0& cos\mathrm{\θ}\end{array}\right];$

Rotate Φ angle according to around x-axis, calculate $c3=\left[\begin{array}{ccc}1& 0& 0\\ 0& \cos \mathrm{\φ}& \sin \mathrm{\φ}\\ 0& -\sin \mathrm{\φ}& \cos \mathrm{\φ}\end{array}\right].$

5. as claimed in claim 4 for the earth magnetism modification method of the angle of pitch of four rotor wing unmanned aerial vehicles, it is characterized in that, in described step S3, calculate the aspect matrix of described four rotor wing unmanned aerial vehicles according to described rotation matrix, comprise the steps:

Carrier system is changed to reference to system, c according to described rotation matrix _n ^b=c3c2c1;

Then described aspect Matrix C is calculated _b ⁿfor:

$\begin{array}{c}{C}_b^n=\left[\begin{array}{ccc}{C}_{11}& C_{12}& C_{13}\\ C_{21}& C_{22}& C_{23}\\ C_{31}& C_{32}& C_{33}\end{array}\right]=\\ \left[\begin{array}{ccc}\cos \mathrm{\θ}\cos \mathrm{\ψ}& -\cos \mathrm{\Φ}\sin \mathrm{\ψ}+\sin \mathrm{\Φ}\sin \mathrm{\θ}\cos \mathrm{\ψ}& \sin \mathrm{\Φ}\sin \mathrm{\ψ}+\cos \mathrm{\Φ}\sin \mathrm{\θ}\cos \mathrm{\ψ}\\ \cos \mathrm{\θ}\sin \mathrm{\ψ}& \cos \mathrm{\Φ}\cos \mathrm{\ψ}+\sin \mathrm{\Φ}\sin \mathrm{\θ}\sin \mathrm{\ψ}& -\sin \mathrm{\Φ}\cos \mathrm{\ψ}+\cos \mathrm{\Φ}\sin \mathrm{\θ}\sin \mathrm{\ψ}\\ -\sin \mathrm{\θ}& \sin \mathrm{\Φ}\cos \mathrm{\θ}& \cos \mathrm{\Φ}\cos \mathrm{\ψ}\end{array}\right]\end{array}.,$

Wherein,

$\mathrm{\Φ}={\arctan }^{\[\frac{c_{32}}{c_{33}}\]}$

$\mathrm{\θ}={\arcsin }^{\[-c_{31}\]}$

$\mathrm{\ψ}={\arctan }^{\[\frac{c_{21}}{c_{11}}\]}.$

6. as claimed in claim 5 for the earth magnetism modification method of the angle of pitch of four rotor wing unmanned aerial vehicles, it is characterized in that, in described step S4, according to the projection of described earth magnetism in reference frame, rotation matrix and flight attitude matrix computations earth magnetism angle of pitch modified value θ d be:

θd＝arcsin(yb/xb)，

Wherein,

$\begin{array}{c}\left[\begin{array}{c}{x}_b\\ y_b\\ z_b\end{array}\right]=c_3{c}_1\left[\begin{array}{c}{x}_b^{11}\\ y_b^{11}\\ z_b^{11}\end{array}\right]=\left[\begin{array}{ccc}1& 0& 0\\ 0& \cos \mathrm{\φ}& \sin \mathrm{\φ}\\ 0& -\sin \mathrm{\φ}& \cos \mathrm{\φ}\end{array}\right]\left[\begin{array}{ccc}\cos \mathrm{\ψ}& \sin \mathrm{\ψ}& 0\\ -\sin \mathrm{\ψ}& \cos \mathrm{\ψ}& 0\\ 0& 0& 1\end{array}\right]=\\ \left[\begin{array}{ccc}\cos \mathrm{\ψ}& \sin \mathrm{\ψ}& 0\\ \sin \mathrm{\ψ}\cos \mathrm{\φ}& \cos \mathrm{\ψ}\cos \mathrm{\φ}& \sin \mathrm{\φ}\\ \sin \mathrm{\ψ}\sin \mathrm{\φ}& -\cos \mathrm{\ψ}\sin \mathrm{\φ}& \cos \mathrm{\φ}\end{array}\right]\left[\begin{array}{c}{x}_b^{11}\\ y_b^{11}\\ z_b^{11}\end{array}\right],\end{array}$

Wherein, $\left[\begin{array}{c}{x}_b^{11}\\ y_b^{11}\\ z_b^{11}\end{array}\right]$ For the projection of earth magnetism in reference frame.

7., as claimed in claim 6 for the earth magnetism modification method of the angle of pitch of four rotor wing unmanned aerial vehicles, it is characterized in that, in described step S5, the angle of pitch of described four rotor wing unmanned aerial vehicles according to the correction of earth magnetism angle of pitch modified value, comprises the steps:

θ1＝θ _{_1}-k×(θg-θd)，

Wherein, θ 1 is the revised angle of pitch, θ _{_ 1}pitching angle theta 1, the θ g calculated for the last time is that body rotates luffing angle around y-axis, and θ g=(Φ, θ, ψ), k are predetermined coefficient.

8., as claimed in claim 7 for the earth magnetism modification method of the angle of pitch of four rotor wing unmanned aerial vehicles, it is characterized in that, the span of k is 0.4 ~ 0.6.