CN104155979B - A magnetic navigation intelligent vehicle positioning device and method based on magnetic field symmetry - Google Patents

Abstract

The invention relates to a magnetic navigation intelligent vehicle positioning device and method based on magnetic field symmetry, comprising: a plurality of magnetic nails, which are equidistantly laid on the ground, for generating a symmetrical magnetic field; a magnetic sensor, which is provided with a plurality , installed equidistantly in front of the smart car in the same horizontal plane, and vertically intersecting with the magnetic nail, for detecting the magnetic field strength of the magnetic nail; the ultrasonic sensor is installed on the smart car, and is installed with the magnetic sensor on the The same horizontal height is used to detect the height of the magnetic sensor from the magnetic nail; the microcontroller unit is used to receive the data of the magnetic sensor and the ultrasonic sensor and perform data processing; CAN communication interface, the microcontroller unit passes through the CAN communication interface Communication connection with the vehicle controller. Compared with the prior art, the present invention has the advantages of simplicity, strong adaptability, high positioning accuracy and the like.

Description

A magnetic navigation intelligent vehicle positioning device and method based on magnetic field symmetry

technical field

The invention relates to the technical field of smart cars, in particular to a magnetic navigation smart car positioning device and method based on magnetic field symmetry.

Background technique

In the existing magnetic navigation technology, there has been no major breakthrough in improving the driving speed of the magnetic navigation smart car. The root cause is that the magnetic field generated by the induced magnetic nail decays quickly, the effective range is small, the amount of data is large, and the magnetic field is susceptible to interference, which makes the vehicle When driving along the magnetic nail path, accurate positioning is impossible, the control cycle becomes longer, and the stability of the vehicle cannot be guaranteed. The vehicle can still reach an ideal working state when there are guardrails on both sides of the road to assist positioning. The magnetic nail path cannot be perfectly adapted.

Contents of the invention

The purpose of the present invention is to provide a simple, adaptable and high positioning accuracy magnetic navigation smart car positioning device and method based on magnetic field symmetry in order to overcome the above-mentioned defects in the prior art.

The purpose of the present invention can be achieved through the following technical solutions:

A magnetic navigation smart car positioning device based on magnetic field symmetry, comprising:

There are multiple magnetic nails, which are equidistantly laid on the ground to generate a symmetrical magnetic field;

The magnetic sensor is provided with a plurality of equidistant installations in the front of the smart car in the same horizontal plane, and is vertically intersected with the magnetic nails for detecting the magnetic field strength of the magnetic nails;

The ultrasonic sensor is installed on the smart car, and is installed at the same level as the magnetic sensor, and is used to detect the height of the magnetic sensor from the magnetic nail;

Microcontroller unit for receiving data from magnetic sensors and ultrasonic sensors and performing data processing;

A CAN communication interface, through which the microcontroller unit communicates with the vehicle controller.

The magnetic nail is a cylindrical magnetic nail.

The magnetic sensor is a three-axis magnetic sensor capable of detecting magnetic field strength in three directions of X, Y, and Z.

A magnetic navigation intelligent vehicle positioning method based on magnetic field symmetry, comprising:

The magnetic field strength acquisition step is to obtain the magnetic field strength values in the three directions of X, Y, and Z;

The height acquisition step is to obtain the height value of the magnetic sensor from the magnetic nail;

The calibration step is to calibrate the relationship coefficient of the cubic spline function between the data in the plane at different heights from the surface of the magnetic nail;

The lateral and longitudinal deviation displacement calculation step is to calculate the lateral and longitudinal displacement of the smart car deviating from the magnetic nail.

The step of obtaining the magnetic field strength specifically includes: the magnetic sensor detects the magnetic field strength values in the X, Y, and Z directions of the magnetic nail and sends them to the microcontroller unit.

The height acquisition step is specifically: the ultrasonic sensor counts the pulses, and obtains the height value of the magnetic sensor from the magnetic nail in real time in an interrupted manner, and sends the pulse number to the microcontroller unit, and the microcontroller unit calculates the magnetic value according to the pulse number. The height value of the sensor from the magnetic nail.

The calibration step specifically includes: the microcontroller unit uses the symmetry of the magnetic field to calibrate the relationship coefficient of the cubic spline function between the magnetic field data at different heights from the surface of the magnetic nail according to the height value and the magnetic field strength value.

The steps for calculating the lateral and longitudinal deviation displacements are specifically:

a) Determine whether the magnetic field data is valid according to the height value obtained in real time, and interpolate to obtain the cubic spline function relationship coefficient corresponding to the current height;

b) Obtain the two largest magnetic field strength values and their corresponding magnetic sensors according to the collected magnetic field strength values, so as to determine the area where the magnetic nail is located;

c) Combining the relationship coefficient of the cubic spline function, the interval where the magnetic nail is located and the known distance between two adjacent magnetic sensors, solve the triangle to get the lateral and longitudinal displacement of the vehicle away from the magnetic nail, and send the information to the whole vehicle controller.

Compared with the prior art, the present invention has the following characteristics:

(1) The device of the present invention is simple, easy to install, and reduces cost;

(2) The symmetry law of the magnetic field of the magnetic nail is fully utilized, and the accuracy of the data can be screened and corrected by itself. At the same time, the relationship between the data is consistent with the cubic spline function, which is convenient for analysis and processing by Matlab to obtain the calibration coefficient.

(3) The ultrasonic sensor detects the distance between the magnetic sensor and the surface of the magnetic nail in real time, combined with the calibrated cubic spline function relationship coefficient at different heights, to effectively realize the accurate positioning of the vehicle when it jumps up and down.

(4) The magnetic sensors are installed at equal intervals, and the displacement deviation is calculated by solving the triangle, so that the vehicle's horizontal and vertical high-precision positioning is realized.

(5) No need for auxiliary positioning on both sides of the road, good adaptability to roads, and reduced road laying costs.

Description of drawings

Fig. 1 is the schematic layout diagram of positioning device of the present invention;

Fig. 2 is a schematic diagram of the relationship between the components of the positioning device of the present invention;

Fig. 3 is a schematic flow chart of the positioning method of the present invention;

Fig. 4 is a spatially symmetrical magnetic field distribution diagram of the magnetic nail of the present invention;

Fig. 5 is a schematic diagram of the magnetic field data graph and fitting graph in the application example.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is carried out on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

As shown in Figure 1, a magnetic navigation smart car positioning device based on magnetic field symmetry includes a magnetic nail 1, a magnetic sensor 2, an ultrasonic sensor 3, a microcontroller unit 4 and a CAN communication interface, and the microcontroller unit 4 is connected to the The magnetic sensor 2, the ultrasonic sensor 3 and the CAN communication interface, the CAN communication interface communicates with the vehicle controller, and the microcontroller unit 4 and the CAN communication interface are installed on the magnetic navigation controller board. In this embodiment, 0# to 12# are 13 magnetic sensors, which are installed in front of the smart car at intervals of 10cm and horizontally equidistant, and are used to detect the magnetic field strength of the magnetic nail. The magnetic sensors can detect magnetic fields in three directions: X, Y, and Z The strength of the three-axis magnetic sensor; No. I and No. II are two ultrasonic sensors installed in the same height plane as the magnetic sensor, with an interval of 90cm, used to detect the height of the magnetic sensor from the magnetic nail; there are multiple magnetic nails, to Lay vertically equidistantly at intervals of 100cm, and the magnetic nails are cylindrical magnetic nails with a diameter of 30mm and a height of 20mm. The height between the magnetic sensor and the ground is 20cm, and the height will fluctuate during actual vehicle operation.

As shown in Figure 2, it is the relationship of each part of the positioning device of the present invention: the relationship 101 is that the symmetrical magnetic field (as shown in Figure 4) produced by the magnetic nail acts on the magnetic sensor, and the relationship 102 is that the magnetic sensor reads the magnetic field strength value, due to the selected The magnetic sensor is a three-axis type, so it can read the magnetic field strength data in the three directions of X, Y, and Z respectively. The relationship 103 determines the distance between the magnetic sensor and the ground. For the message of the dormancy command, the relationship 105 is that the microcontroller unit sends a message containing vehicle position information to the vehicle controller, and the relationship 106 is fault diagnosis. After a fault is detected, a fault code is generated through the relationship 107 and sent to the vehicle controller .

As shown in Figure 3, the positioning method of the above-mentioned magnetic navigation intelligent vehicle positioning device based on magnetic field symmetry is as follows:

Step 301, power on the system;

Step 302, start the self-diagnosis of each module, if a fault is detected, go to step 303, if there is no abnormality in each module, then go to step 304;

Step 303, generating a corresponding fault code and sending it to the vehicle controller through the CAN bus;

Step 304, first enable the magnetic sensor, and then scan the magnetic field strength values of the 13 sensors in X, Y, and Z directions in sequence;

Step 305, filtering out the influence of the interfering magnetic field, and judging an exact section among the 26 sections divided by 13 magnetic sensors where the magnetic nail is located according to the data in the Z direction and the Y direction;

Step 306, selecting the data of the two magnetic sensors corresponding to the section to calculate the total magnetic field strength value;

Step 307, first calculate the height of the current sensor from the surface of the magnetic nail, that is, the ground, according to the signal returned by the ultrasonic wave, and determine whether the obtained magnetic field strength value is valid, that is, whether it is in a circle with the magnetic nail as the center and a radius of 25 cm; if so, the data is valid , execute step 308, otherwise the data is invalid, go to step 304;

Step 308, refer to the obtained height value interpolation to obtain the cubic spline function relationship coefficient corresponding to the current height, and calculate the linear distance between the two adjacent magnetic sensors on the upper surface of the magnetic nail, that is, the ground projection and the magnetic nail;

Step 309 , using the known distance between the magnetic sensors, the lateral and longitudinal displacements of the vehicle deviating from the magnetic nail path can be calculated by solving the triangle, and the displacement information is generated into a CAN message and sent to the vehicle controller.

Fig. 5 shows the magnetic field data graph and fitting graph in the application example of the present invention. The vertical axis represents the straight-line distance from the magnetic nail to the horizontal plane of the magnetic sensor projection, in cm, and the horizontal axis represents the combined magnetic field strength in the X, Y, and Z directions, in the unit of 5.25mG/LSB.

Claims (6)

1. A magnetic navigation smart car positioning device based on magnetic field symmetry, characterized in that it comprises: There are multiple magnetic nails, which are equidistantly laid on the ground to generate a symmetrical magnetic field; The magnetic sensor is provided with a plurality of equidistant installations in the front of the smart car in the same horizontal plane, and is vertically intersected with the magnetic nails for detecting the magnetic field strength of the magnetic nails; The ultrasonic sensor is installed on the smart car, and is installed at the same level as the magnetic sensor, and is used to detect the height of the magnetic sensor from the magnetic nail; Microcontroller unit for receiving data from magnetic sensors and ultrasonic sensors and performing data processing; CAN communication interface, the microcontroller unit communicates with the vehicle controller through the CAN communication interface; The positioning method of the magnetic navigation smart car positioning device includes: The magnetic field strength acquisition step is to obtain the magnetic field strength values in the three directions of X, Y, and Z; The height acquisition step is to obtain the height value of the magnetic sensor from the magnetic nail; The calibration step is to calibrate the relationship coefficient of the cubic spline function between the data in the plane at different heights from the surface of the magnetic nail; The lateral and longitudinal deviation displacement calculation step calculates the lateral and longitudinal displacement of the smart car deviating from the magnetic nail; The steps for calculating the lateral and longitudinal deviation displacements are specifically: a) Determine whether the magnetic field data is valid according to the height value obtained in real time, and interpolate to obtain the cubic spline function relationship coefficient corresponding to the current height; b) Obtain the two largest magnetic field strength values and their corresponding magnetic sensors according to the collected magnetic field strength values, so as to determine the area where the magnetic nail is located; c) Combining the relationship coefficient of the cubic spline function, the interval of the magnetic nail and the known distance between two adjacent magnetic sensors, the triangle is solved to obtain the lateral and longitudinal displacement of the vehicle away from the magnetic nail, and send it to the vehicle controller . 2. A magnetic navigation intelligent vehicle positioning device based on magnetic field symmetry according to claim 1, wherein the magnetic nail is a cylindrical magnetic nail. 3. A magnetic navigation intelligent vehicle positioning device based on magnetic field symmetry according to claim 1, wherein the magnetic sensor is a three-axis magnetic sensor capable of detecting magnetic field strength in three directions of X, Y, and Z . 4. A magnetic navigation intelligent vehicle positioning device based on magnetic field symmetry according to claim 1, wherein the magnetic field intensity acquisition step is specifically: the magnetic sensor detects the three directions of magnetic nails X, Y, and Z. The magnetic field strength value is sent to the microcontroller unit. 5. A magnetic navigation intelligent vehicle positioning device based on magnetic field symmetry according to claim 1, wherein the height acquisition step is specifically: the ultrasonic sensor counts pulses, and acquires the magnetic sensor in real time in an interrupted manner. The height value of the distance from the magnetic nail, and the pulse number is sent to the microcontroller unit, and the microcontroller unit calculates the height value of the magnetic sensor from the magnetic nail according to the pulse number. 6. A magnetic navigation intelligent vehicle positioning device based on magnetic field symmetry according to claim 1, wherein the calibration step is specifically: the microcontroller unit utilizes the magnetic field symmetry according to the height value and the magnetic field strength value Calibrate the cubic spline function relationship coefficient between the magnetic field data in the plane at different heights from the surface of the magnetic nail.