CN111398876A

CN111398876A - Center positioning method based on magnetic induction line direction

Info

Publication number: CN111398876A
Application number: CN202010237957.3A
Authority: CN
Inventors: 樊恒; 易晟阳; 郑华强
Original assignee: Shanghai Maikeluo Automation Technology Co ltd
Current assignee: Shanghai Maikeluo Automation Technology Co ltd
Priority date: 2020-03-30
Filing date: 2020-03-30
Publication date: 2020-07-10

Abstract

The invention discloses a center positioning method based on a magnetic induction line direction, which mainly uses a magnet or an electromagnet as a signal source, adopts at least 3 sensors to carry out axisymmetric array arrangement as a receiver, establishes a coordinate system by taking a symmetric center as a coordinate origin and an axisymmetric line as a Z axis, correspondingly outputs a component value in the X, Y direction by each sensor according to the sensed magnetic induction line direction when the receiver is close to the signal source, solves a linear equation of a connecting line between each sensor and the signal source center by using the component value and the position of the sensor, and can solve a linear intersection point by using any two linear equations, namely determines the center position of the signal source. The method utilizes the direction of the magnetic induction line to detect the position of the signal source, is irrelevant to the absolute intensity of a magnetic field, and does not need to calibrate and compensate the offset and proportion of the sensor, so that the positioning method and the positioning steps are simpler, and the positioning precision is higher.

Description

Center positioning method based on magnetic induction line direction

Technical Field

The invention relates to the technical field of machining, in particular to a center positioning method based on a magnetic induction line direction.

Background

The aircraft structure material is mainly aluminum alloy and carbon fiber composite material, and the two materials are non-magnetic and have magnetic conductivity close to air, and a magnetic field can penetrate through the two materials without being influenced. Therefore, the cylindrical permanent magnet can be placed in the blind hole, and the position of the center of the permanent magnet is detected through the structural material through the magnetic field, so that the accurate position of the blind hole is obtained.

The traditional method for positioning the permanent magnet by the blind hole instrument generally arranges a plurality of magnetic field intensity sensors into a circle, and fits a magnetic field intensity model according to the measured values of the sensors to obtain the position of the permanent magnet. The use of magnetic field strength to probe permanent magnets has the following disadvantages:

1. due to the manufacturing reasons of the sensors, the measurement zero points of the sensors are different, the readings of the sensors are slightly different even if the external magnetic field strength is the same, and the linear proportion of each sensor is different, namely when the external magnetic field strength is changed, the change rate of each sensor is different; the difference between the zero point and the linear proportion between the sensors causes that complicated calibration operation is needed when the sensor is used, and the offset and the proportion of the sensors are generally calibrated at different positions relative to the sensors by using a reference permanent magnet to form a complicated calibration data set;

2. the sensors have the zero drift problem, so that the zero point of the sensor changes along with the change of time, and the deviation of the measurement position of the blind hole instrument based on the magnetic field intensity is directly caused;

3. obtaining the magnetic field center coordinate position from the magnetic field intensity requires using a complex mathematical model, and calculating the mathematical model requires a CPU chip with stronger computing power, so that the complexity, the volume and the power consumption of the control system are improved.

Disclosure of Invention

In order to overcome the defects of the existing blind hole position finder for detecting the permanent magnet by using the magnetic field intensity, the invention aims to solve the technical problems that: the center positioning method based on the magnetic induction line direction is more accurate in positioning and simpler in process and calculation.

The technical scheme adopted by the invention for solving the technical problems is as follows:

the center positioning method based on the magnetic induction line direction takes a magnet or an electromagnet as a signal source and a sensor capable of inducing the magnetic induction line direction as a receiver, and the center positioning method is operated according to the following steps:

step 1, performing axisymmetric array arrangement by adopting at least 3 sensors to serve as a receiver, and establishing a coordinate system by taking a symmetric center as a coordinate origin and an axisymmetric line as a Z axis to obtain the central position of each sensor;

step 2, a signal source is arranged at a positioning point, and a magnetic pole connecting line at two ends of the signal source is parallel to the Z axis;

and 3, enabling the receiver to be close to the signal source, enabling each sensor to correspondingly output a component value in the direction X, Y according to the direction of the sensed magnetic induction line, solving a linear equation of a connecting line between each sensor and the center of the signal source by using the component value and the position of the sensor, and solving the intersection point of the straight lines, namely the center position of the signal source by using any two linear equations.

Further, the signal source adopts a cylindrical permanent magnet.

Further, in the step 1, 6-8 sensors are adopted to be arranged in an axisymmetric array to serve as receivers.

Further, in step 3, when the receiver is close to the signal source, the projection position of the signal source on the XY plane is located within the array range of the sensor, and then the subsequent calculation is performed.

Further, the method comprises a step 4 of solving a plurality of straight line intersection points by using a plurality of groups of straight line equations, and obtaining an optimal position as the central position of the signal source by means of averaging.

Further, the signal source is replaced by a transmitter capable of generating an electric field or a gravitational field, and the sensor is replaced by a corresponding receiver capable of sensing the direction of the electric field or the gravitational field.

The invention has the beneficial effects that: the method and the device utilize the direction of the magnetic induction line to detect the position of a signal source, use the component of the magnetic induction line in the direction X, Y as a measured value, are irrelevant to the absolute strength of a magnetic field, have small difference or drift in the measurement zero point of the sensor, have small influence on the direction of the magnetic field, and do not need to calibrate and compensate the offset and the proportion of the sensor, so the positioning mode and the step are simpler, and the positioning precision is higher.

Drawings

FIG. 1 is a schematic diagram of a sensor array.

Fig. 2 is a schematic diagram of a positioning process.

Fig. 3 is a projection schematic diagram of a magnetic induction line emitted by a signal source on an XY plane.

Fig. 4 is a schematic diagram of a calculation process.

Labeled in the figure as 1-sensor, 2-circuit substrate, 3-receiver, 4-structure, 5-blind hole, 6-signal source.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

step 1, as shown in fig. 1 and fig. 2, at least 3 sensors 1 are adopted to perform axisymmetric array arrangement to serve as receivers 3, a coordinate system is established by taking a symmetric center as a coordinate origin and an axisymmetric line as a Z axis, and for convenience of positioning and calculation, the surface where the sensors 1 are located can be taken as an XY plane to obtain the central position of each sensor 1;

step 2, placing a signal source 6 at a positioning point, as shown in fig. 2, when determining the position of a blind hole on an airplane wing, placing the signal source 6 in the blind hole 5 on the structural member 4, and enabling a magnetic pole connecting line at two ends of the signal source 6 to be parallel to a Z axis, so as to enable the projection of a magnetic induction line on an XY plane to be uniform and radial, as shown in fig. 3, thereby ensuring that the sensor 1 can judge the direction of the signal source 6;

step 3, as shown in fig. 2, the receiver 3 is close to the signal source, each sensor 1 correspondingly outputs a component value in the direction X, Y according to the sensed magnetic induction line direction, a linear equation of each sensor 1 connecting with the center of the signal source 6 is solved by using the component value and the position of the sensor 1, as shown in fig. 4, for example, the position of the sensor a is (x0, y0), the sensor output value (vx, vy), the straight line is y ═ kx + c, k ═ vy/vx, and c can be solved by substituting (x0, y0), so as to determine a linear equation, and the intersection point of the straight lines, i.e., the center position of the signal source, can be solved by using any two linear equations. Because lines are more, for convenience, the actual calculation process can adopt a matrix for calculation.

When the signal source 6 and the receiver 3 are determined, the signal source 6 is preferably a cylindrical permanent magnet, the use is simple and convenient, and the magnetic field is stable; the receiver 3 adopts 6 ~ 8 sensors 1 to carry out the axial symmetry array and arranges and form to improve measurement accuracy, as to the scope size of array, rationally select according to use scene and magnetic field intensity.

Furthermore, when the receiver 3 is brought close to the signal source 6 in step 3, the projected position of the signal source 6 on the XY plane is preferably brought into the array range of the sensor 1 by human judgment or by other positioning means, and then subsequent calculation is performed. Because if the signal source is too far away from the array of sensors 1, the magnetic field intensity is reduced, which easily causes the positioning inaccuracy, and also increases the positioning time, which does not meet the setting requirement of accurate positioning.

Furthermore, in order to improve the positioning accuracy, the method further comprises a step 4 of obtaining an optimal position as the center position of the signal source by averaging after solving the intersection points of the plurality of straight lines by using the plurality of sets of straight line equations in the step 3, that is, the x values and the y values of all the points are respectively averaged to be used as the positioning points.

After the central position of the signal source 6 is obtained, a relative position relation can be formed between the central position and the coordinate origin of the receiver 3, and the position of the blind hole can be determined by moving the position of the receiver 3 by using other translation mechanisms to enable the coordinate origin to coincide with the center of the signal source 6.

According to the above positioning principle, other physical fields with directions can also be used for positioning purposes, such as a transmitter capable of generating an electric field or a gravitational field as a signal source, and a sensor capable of sensing the direction of the electric field or the gravitational field as a receiver, which are only more troublesome in hardware manufacturing and more costly.

The method utilizes the direction of the magnetic induction line to detect the position of a signal source, uses the component of the magnetic induction line in the direction X, Y as a measured value, and is irrelevant to the absolute strength of a magnetic field, even if the zero point of the sensor measurement has slight difference or drift, the influence on the direction of the magnetic field is small, the calibration compensation for the offset and the proportion of the sensor is not needed, the only calibration possibly needed is the measurement center position of a single sensor, but because the difference of the measurement center positions of the sensors in the same batch is small, the whole offset can be generally carried out on the measurement center of the whole array, and only one group of X, Y compensation values are needed.

Claims

1. The center positioning method based on the direction of the magnetic induction line is characterized by comprising the following steps:

the method is characterized in that a magnet or an electromagnet is used as a signal source, a sensor capable of inducing the direction of magnetic induction lines is used as a receiver, and the method comprises the following steps:

2. The method for centering on the magnetic induction line direction as claimed in claim 1, wherein: the signal source adopts a cylindrical permanent magnet.

3. The method for centering on the magnetic induction line direction as claimed in claim 1, wherein: in the step 1, 6-8 sensors are adopted to be arranged in an axisymmetric array to serve as receivers.

4. The method for centering on the magnetic induction line direction as claimed in claim 1, wherein: in step 3, when the receiver is close to the signal source, the projection position of the signal source on the XY plane is firstly positioned in the array range of the sensor, and then the subsequent calculation is carried out.

5. The method for centering on the magnetic induction line direction as claimed in claim 1, wherein: and 4, solving a plurality of straight line intersection points by using a plurality of groups of straight line equations, and obtaining an optimal position serving as the central position of the signal source in an averaging mode.

6. The method for centering on the magnetic induction line direction as claimed in any one of claims 1 to 5, wherein: the signal source is replaced by a transmitter capable of generating an electric field or a gravitational field, and the sensor is replaced by a corresponding receiver capable of sensing the direction of the electric field or the gravitational field.