JPH0194287A - Magnetic body detector - Google Patents

Abstract

PURPOSE:To magnify a range utilizable in steering control, by arranging a pair of guide sensors having detection parts each having a shape magnified fanwise from the center linen of an unmanned feed vehicle to the outside at left and right symmetric positions. CONSTITUTION:A pair of guide sensors having detection parts each having a shape magnified fanwise from the center line of an unmanned feed vehicle to the outside are arranged at left and right symmetric positions so as to hold the center line of the unmanned vehicle therebetween. When these trapezoidal inductance type guide sensors 1, 2 are used, each of the detection parts is laterally long and the shape thereof is magnified from the center (l) to the lateral side and, therefore, the peak interval (+ or - max. output interval) of a differential output signal is -4-+4 and magnified by about two times as compared with a case using circular inductance type sensors. Since both peaks are connected by a curve having a gentle gradient almost near to a straight line, a precise posture control signal is obtained on the basis of the output signal waveform thereof. Further, the radius of curvature of a curve guide path can be suppressed small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a guidance detector used for steering control of an automatic guided vehicle.

[Conventional technology]

Conventionally, 1 is used to guide automated guided vehicles (hereinafter referred to as AGV).
Various methods have been developed, and the diversification of AGV control has made the guideway more complex, and as a result, there is a need for higher accuracy of the guide sensor of the AGV's guidance detector.

The main function of currently used guide sensors is to output the left and right deviations from the magnetic markings on the guideway with respect to the direction of travel, as well as the magnitude thereof. However, the steering control range for the amount of left and right deviation from the magnetic marker is limited by the width of the marker and the size and spacing of the sensors, and cannot be secured very widely. For this reason, it is difficult to achieve high precision in AGV steering control.

[Problem that the invention seeks to solve]

By the way, the circular inductance type coil is used as the sensor 11.
When used in the No. 12 detection section, the left and right deviation from the magnetic marker serving as the guideway in the direction of travel and the magnitude of the signal output change as shown in FIG.

According to FIG. 2, the range that can be used for AGV steering control is between -2 and +2, which is quite narrow. Therefore, it is necessary to ensure a large radius of curvature for the curved portion of the taxiway, which has various drawbacks, such as making it impossible for the AGV to make small turns.

An object of the present invention is to provide a magnetic substance detector whose range of use for AGV steering control is expanded.

[Means for solving problems]

The present invention relates to a magnetic material detector in which an automatic guided vehicle is equipped with a guide sensor that detects a magnetic material guide on the road and outputs a steering control signal for the vehicle body. This is a magnetic substance detector characterized in that a pair of guide sensors each having a detection part in an enlarged shape are arranged at symmetrical positions across the center line of an automatic guided vehicle.

[Principle/effect]

The present invention basically utilizes the fact that the inductance L of the coil changes when a magnetic material approaches the leakage magnetic field of the sensor coil.

Coil inductance L is given by the following equation.

μ: Magnetic permeability N: Number of coil turns A: Coil cross-sectional area Q: Magnetic path length As the magnetic body approaches the sensor coil, μ of the coil changes. Furthermore, the inductance of the sensor coil is also proportional to its cross-sectional area. By utilizing this point and adjusting the cross-sectional area of the coil, it is possible to control the sensor output.

Therefore, as shown in FIG. 2, the present invention provides a detection section that expands from the center line Ω of the vehicle body of the automatic guided vehicle toward the left and right outwards across the center line 0 of the vehicle body of the automatic guided vehicle. Specifically, a pair of guide sensors 1 and 2 having trapezoidal or triangular detection portions are used, and these are installed at symmetrical positions across the center line Q of the vehicle body. This expands the control range of the vehicle and enables stable driving.

〔Example〕

Examples of the present invention are shown below.

An amorphous alloy tape was used as the magnetic material, and a comparison test was conducted on the output characteristics based on the difference in output signals of the detection sections of two guide sensors included in the detector.

1) Object to be detected (magnetic material): Amorphous alloy tape (
(Made by Japan Amorphous Metal ■) Model name: METAGLAS 2705M Dimensions: Width 25 fields, thickness 0.025 m + 2) Measurement conditions Sensor used: Inductance variable sensor ■ Circular inductance type sensor Sensor coil dimensions: φ20wn ■ Trapezoidal inductance Type sensorSensor coil dimensions: φ5 to φ20+nm3) Measurement method The distance between the sensor and the object to be detected was set to 20 mm, and the sensor output was measured when the object to be detected was moved laterally with respect to the sensor.

4) Measurement results The measurement results are shown in Figures 1 and 2. According to the present invention using a trapezoidal inductance type sensor, it is horizontally elongated and the shape of the detection part expands from the center Q toward the side, so that the maximum output of the peak interval c± of the differential output signal is It can be seen that the peak interval) is -4 to +4, which is twice as large as the peak interval of -2 to +2 in the detector shown in Figure 1, which uses a circular inductance type sensor. . Furthermore, since the two peaks are connected by a curve with a gentle slope that is almost a straight line, a precise attitude control signal can be obtained based on the output signal waveform.

〔Effect of the invention〕

As described above, the detector of the present invention expands the detection output range that can be used for AGV steering control to more than twice that of conventional detectors, enables highly accurate attitude control of the AGV, and furthermore This has the effect of keeping the radius of curvature small.

[Brief Description of the Drawings] Fig. 1 is a diagram showing the output signal of the trapezoidal inductance type sensor according to the present invention and the relative position of the sensor detection section that generates the output signal, and Fig. 2 is the output of the conventional circular inductance type sensor. FIG. 3 is a diagram illustrating the relative position of a sensor sensing portion that produces a signal and an output signal; 1.2... Guide sensor Q... Center line of automatic guided vehicle A... Output signal waveform by trapezoidal inductance type sensor

Claims (1)

[Claims] (1) In a magnetic material detector equipped with an automatic guided vehicle equipped with a guide sensor that detects a magnetic material guide on the road and outputs a steering control signal for the vehicle body, the sensor extends outward from the center line of the automatic guided vehicle. 1. A magnetic substance detector characterized in that a pair of guide sensors each having a detection part in an enlarged shape are arranged at symmetrical positions across the center line of an automatic guided vehicle.