JPH0226729B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention corresponds to the direction to be detected by sensing the earth's magnetism in order to detect the running direction of the vehicle body.
In addition, the present applicant has already proposed a method for detecting the direction of a running vehicle equipped with a direction sensor that outputs a pair of voltage signals having a phase difference of 90 degrees in Japanese Patent Application No. 57-121564, etc., for an unmanned vehicle. In particular, the present invention relates to a method of detecting the direction of a traveling vehicle that can be suitably used.

Conventionally, in this type of driving vehicle, especially in automatic driving vehicles configured to perform at least part of the driving control automatically, it is necessary to detect the driving direction, so it is possible to detect all directions. It is considered that a geomagnetic sensor can be used as a direction sensor.

However, although the geomagnetic sensor described above is capable of detecting all directions of 360 degrees, in order to do so, the detection direction must be determined based on the values of both of a pair of signals having a 90 degree phase difference. When sampling the azimuth information necessary for the teaching/playback control of unmanned vehicles, which has already been proposed, the signal processing of the sampled data becomes complicated, and the amount of memory used to store the data increases. There was an inconvenience.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to determine the direction of a traveling vehicle by using a simplified signal to determine the direction based on a pair of voltage signals output from a direction sensor. The purpose is to provide a detection method.

In order to achieve the above object, the present invention compares one of the voltage signals with the maximum and minimum average values of the one voltage signal, and outputs the one voltage signal corresponding to the azimuth. adding a positive or negative sign to the other of the voltage signals output corresponding to the direction in determining whether or not exceeds the average value;
The azimuth in the running direction of the vehicle body is detected based on the positive/negative sign and the magnitude of the other voltage signal.

Next, the operation of the present invention will be explained based on FIG. 2B of the embodiment described later. When the orientation sensor is rotated 360 degrees, two voltage signals Vx and Vy with a phase difference of 90 degrees are obtained as shown in the figure. If one voltage signal Vy is used to sign positive or negative,
Since it is higher than the average value Yp in the southeast, it is determined to be positive.
Since it is less than the average value Yp between southwest and west, it is determined to be negative.
This positive/negative sign is combined with the other voltage signal Vx output that is output corresponding to the direction, for example,
The other voltage signal Vx is the same between the southeast and southwest areas, but after determining whether it is in the southeast or southwest range by referring to the positive and negative signs, the magnitude of the other voltage signal Vx is determined. to find the exact direction. The areas between northwest and northeast are also detected in the same way.

Therefore, according to the present invention, the following effects can be obtained.

In other words, the running direction can be determined 360 degrees from only one type of signed voltage signal, which is obtained by adding information obtained by coding one of a pair of voltage signals to the other voltage signal.
The amount of signal processing data needed to determine the direction of travel has been reduced, making it possible to significantly reduce the amount of memory required for sampling and storage.

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a lawn mower 4 is suspended between the front and rear wheels 2 and 3 of the vehicle body 1 so as to be movable up and down, and the direction of travel is detected by sensing the earth's magnetic field in front of the vehicle body 1. A directional sensor 5 is provided at the rear of the vehicle body 1, and a fifth wheel is provided as a distance sensor 6 for continuously detecting the moving distance of the vehicle body 1, thereby configuring a lawn mowing work vehicle as a traveling vehicle that can run unmanned. .

As shown in FIG. 2A, the orientation sensor 5 has a toroidal core 7 provided with an excitation coil Co,
Output coils Cx and Cy are wound diametrically orthogonally to each other from above, and when an external magnetic field (earth's magnetism) is applied to the toroidal core 7, which has alternating current flowing through the excitation coil Co, the output coils Cx and Cy The apparatus is configured to generate an alternating current signal proportional to an external magnetic field. The AC signal voltages generated in the output coils Cx and Cy are amplified to a predetermined level and then converted into DC voltages Vx and Vy as shown in FIG. 2B and output.

The toroidal core 7 constituting the orientation sensor 5 is provided with a rotation mechanism A that can freely rotate 360 degrees around the vertical axis P, and the output coil Cx,
It is configured to correct the difference in detected magnetic sensitivity with respect to the direction of Cy, and also to detect the direction of travel of the vehicle body 1 relative to a predetermined direction.

The rotation mechanism A is configured by fixing the toroidal core 7 to a bracket 8 made of non-magnetic material, and providing a motor 9 to freely rotate the bracket 8 in the left and right directions, and a sensor for detecting the rotation angle θ. A potentiometer PM is provided on the axis P as a rotation angle detection device.

On the other hand, the distance sensor 6 is configured to detect a predetermined travel distance lo by generating one pulse for each unit travel distance of the vehicle body 1 and counting this pulse a predetermined number of times by a counter 10. It has been done.

Then, based on each detection signal of the direction sensor 5 and the distance sensor 6 with the above configuration, the vehicle body 1
The direction of travel of the vehicle is determined.

The control device 11 that processes the pair of voltage signals Vx and Vy corresponding to the azimuth from the azimuth sensor 5 will be described below.

As shown in FIG. 3, the DC voltages Vx, Vy as the orientation detection signal from the orientation sensor 5 and the voltage Vo as the sensor rotation angle from the potentiometer PM are transferred to the A/D converter via the signal selector 12. 13, the signal is converted into a digital signal and is input to the calculation unit 15 of the control device 11 via the input/output interface 14. and,
A predetermined number of pulses from the distance sensor 6 counted by the counter 10 (the predetermined moving distance)
lo), the voltages Vx and Vy as azimuth information detected by the azimuth sensor 5 are sampled, one voltage Vy is encoded by the means described later, and one of the encoded voltages Vy is The configuration is such that the value of the other voltage signal Vx to which information about the voltage Vy is added is sequentially stored in a predetermined address area of the memory 16 as sampling data Xn.

By the way, as mentioned above, the predetermined moving distance lo
Before each azimuth sampling, the detection sensitivity for all directions of the earth's magnetic field detected by the azimuth sensor 5 is corrected, and the detected absolute azimuth is adjusted relative to the vehicle body 1 with respect to a predetermined direction of the work area. In order to sample the change in azimuth in the running direction, prior to this sampling, the azimuth sensor 5 is rotated 360 degrees when the vehicle is stopped, and the detected voltages Vx and Vy detected at every predetermined angle θp are sampled. Detection voltage Vx, Vy in reference direction
However, when storing the sampling data Xn and Yn in this detection voltage pattern check, one voltage
Vy and the maximum and minimum average value Yp of one voltage Vy
It is determined whether the one voltage Vy outputted corresponding to the direction exceeds the average value Yp, the result is encoded ±, and this code ±
is added to the other voltage Vx, and only one signed data Xn is finally stored as azimuth information. Then, the direction is determined using this signed data.
Since this can be done based on the size of Xn and its sign ±, the amount of memory 16 used can be extremely reduced.

Incidentally, FIG. 4 is a flowchart showing the operation of the control device 11 when the orientation sensor 5 described above is rotated 360 degrees in advance to sample the orientation.
Other symbols used in FIG. 4 are control flags.

Furthermore, when sampling the detected orientation during actual driving, the pair of detected voltages Vx and Vy of the orientation sensor 5 can be similarly stored as one type of signed data using the above means, so the use of the memory 16 can be similarly simplified. The amount can be saved significantly.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of drawings]

The drawings show an embodiment of a traveling vehicle according to the present invention,
Figure 1 is an overall side view of the lawn mowing vehicle, Figure 2A is a diagram showing the configuration of the orientation sensor, Figure 2B is a waveform diagram of the detected voltage, Figure 3 is a block diagram of the control system, and Figure 4 is a diagram showing the configuration of the orientation sensor. The figure is a flowchart showing the operation of the control device. 1...Vehicle body, 5...Direction sensor, Vx, Vy...
...Voltage signal, Yp...average value.

Claims (1)

[Claims] 1. In a method for detecting the direction of a running vehicle using a direction sensor 5 that senses the earth's magnetism and outputs a pair of voltage signals Vx and Vy having a 90 degree phase difference corresponding to the direction, one of the voltage signals Vx and Vy and the maximum and minimum average value Yp of this one voltage signal are compared, and it is determined whether the one voltage signal output corresponding to the direction exceeds the average value Yp,
The voltage signals Vx and Vy are output in accordance with the direction.
A method for detecting the direction of a running vehicle in which a positive or negative sign is added to the other voltage signal, and the direction of travel of the vehicle body 1 is detected based on the positive or negative sign and the magnitude of the other voltage signal.