JPH0719178B2 - Unmanned guided vehicle abnormality detection method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an abnormality detection method for an automated guided vehicle traveling along a sign strip laid on a traveling path.

[Conventional technology]

Conventionally, an abnormality detection signal for an automated guided vehicle has been output when the automated guided vehicle derails from a sign strip indicating a traveling path.

This method will be described with reference to the drawings.

Fig. 2 shows an automatic guided vehicle using the metal tape 2 as a traveling sign belt and using the metal sensors 3'and 3 ". The metal sensors 3'and 3" having this value are determined according to the positional relationship with the sign belt. It has the characteristics shown in Fig. 3. That is, the maximum output is directly above the marker band, and the output becomes smaller according to the displacement from the maximum. Therefore, when this type of sensor is attached to the automatic guided vehicle 1 as shown in FIG. 2 and the outputs of the sensors 3'and 3 "are measured when the automatic guided vehicle 1 is displaced with respect to the center of the sign strip 2, It has the characteristics shown in the figure.
Derailment can be determined when the levels of the two sensors are both below a certain value.

[Problems to be Solved by the Invention]

The cause of such derailment of the automated guided vehicle is foreign matter on the traveling sign belt. For example, in the case of an automated guided vehicle that uses a metal tape for the marker band and a metal sensor for the sensor, a metal tool,
Similarly, in the case of a light reflecting tape and an optical sensor, such as a part, a case such as a metal that reflects light exists near the traveling sign strip. Since these foreign matters are generally closer to the sensor than the traveling sign zone, the output signal level of the sensor becomes large, and the control circuit of the automatic guided vehicle regards the foreign matter as the sign zone to perform control. As a result, the automated guided vehicle derails from the sign strip. Derailment caused by such foreign matter is not detected by the above-mentioned conventional abnormality detection method until the influence of the foreign matter disappears after derailment, so the distance that the automated guided vehicle travels on a route other than the traveling path is long and dangerous. There was a problem that was.

[Means for Solving the Problems]

An object of the present invention is to provide an abnormality detection method for an automated guided vehicle that solves the above-mentioned problems. Therefore, in the present invention, attention is paid to an increase in the sensor output due to a foreign substance, and the object is achieved by monitoring an abnormal decrease in the output level of the sensor, which has been conventionally performed, and also by monitoring an abnormal increase.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.
In this embodiment, the case where two sensors are used is shown. The output signals of the sensors 3'and 3 "having the output characteristics as shown in FIG. 3 are input to the individual comparator circuits 10 and 11, respectively, and the output signal of the sensor 3'has a lower limit value in the comparator 4 '. The comparator 5'is compared with the upper limit value. The output signals of the sensor 3 "are also compared by the comparators 4" and 5 "in the same manner. Of the output signals of these comparators 4 ', 4 ", 5', 5",
The comparison result with the lower limit value is input to the AND gate 7, and the comparison result with the upper limit value is input to the first OR gate 8.
The output signal of the first OR gate 8 is input to the second OR gate 9, and the output signal of the second OR gate 9 becomes the abnormality detection signal. That is, this abnormality detection signal is output when the output signal levels of the two sensors 3'and 3 "are both below the lower limit value and when the output signal levels of the two sensors 3'and 3" are This is the case when either one exceeds the upper limit. In this way, the foreign matter can be detected by comparing with the upper limit value and the derailment can be detected by comparing with the lower limit value. The upper and lower limits are determined in advance according to the system characteristics and specifications of the automated guided vehicle. Further, the abnormality detection signal is given to a processing circuit (not shown) to perform processing such as stopping the automated guided vehicle and outputting an alarm.

〔The invention's effect〕

As described above, the present invention compares the output signal level of a sensor used in an automatic guided vehicle with two reference signal levels for derailment detection and foreign object detection, and when the sensor signal level is outside the two reference signal levels, an abnormality occurs. By outputting the detection signal, there is an advantage that the abnormality detection signal can be output not only when the automatic guided vehicle is derailed but also when a foreign object on the traveling sign strip is detected.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of an automated guided vehicle using a traveling sign strip, FIG. 3 is a characteristic diagram of a sensor, and FIG. 4 is a sensor of FIG. It is a characteristic view when two are used. 1 to 4, 1 ... Automated guided vehicle, 2 ... Marker band, 3 ', 3 "... Sensor, 4', 4", 5 ', 5 "... Comparator, 6 ... Differential amplifier,
7 ... And gate, 8,9 ... OR gate, 10,11 ... Comparison circuit.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G05D 1/02 E 9323-3H

Claims (1)

[Claims] 1. A sensor for detecting a traveling sign strip laid on a traveling road and an unmanned guided vehicle traveling by an output signal from the sensor, derailment from the traveling sign strip and presence of foreign matter causing the derailment. Is detected by comparing the output signal level of the sensor with a predetermined upper limit value and a lower limit value, and detecting when the value is out of the range.