JPS63204415A - Guiding method for unmanned vehicle - Google Patents

Abstract

PURPOSE:To improve the running stability and reliability of an unmanned vehicle even with the inferior rout conditions by using two detectors to detect the mark substances set on the ground and outputting a steering instruction when the absolute value of the differential output of both detectors exceeds the comparison voltage level which varies in response to the sum output. CONSTITUTION:A sensor consists of detection coils 3a and 3b which detect the mark substances set on the ground and this sensor output varies according to the distance of detection between the sensor and the mark substances. Thus, the differential output between both detection coils has smaller amplitude as the distance of detection increases. A steering signal is outputted when the sensor gets out of its play width and the absolute value of the differential output exceeds the comparison voltage level Vref so that the sensor is set again within said play width. While a sum signal varies according to the height of the sensor and therefore the optimum play width is secured regardless of the height of the sensor by changing the level of Vref in response to the increase/ decrease of the sum signal level. As a result, the running stability and reliability can be improved for an unmanned vehicle even with the inferior route conditions.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for guiding an unmanned vehicle.

[Conventional technology]

Various methods for guiding unmanned vehicles (for example, Japanese Patent Application Laid-Open No. 59-202512 and Japanese Patent Application Laid-open No. 57-130200) have been developed and put into practical use. The steering signal for an unmanned vehicle normally exhibits values of different polarities in response to the left and right deviations of the guidance sensor from the guidance marker, as shown by the curve (a) in FIG. As for the steering method of the car, there is a method in which the amount of steering is determined according to the amount of deviation, and a threshold value (comparison voltage Vref) is set for the amount of deviation of the guidance sensor, and when the amount of deviation exceeds a certain threshold, the vehicle is steered. Both methods have been put into practical use. The former allows fine-grained feedback depending on the amount of deviation, but the control becomes complicated. The latter has simpler control than the former, and is therefore suitable for use in places where precision is not required.

[Problem that the invention seeks to solve]

According to the latter method, as shown in the curve (a) of FIG. 3, the fact that the sensor has deviated from the marker by more than the comparison voltage Vref is determined by the fact that the differential output becomes more than the comparison voltage. Therefore, a steering signal for correcting the deviation as shown in FIG. 3(a') can be obtained for the range of left and right deviations. When the differential output is below the comparison voltage value, there is play that does not result in steering. The amount of play greatly affects the driving performance of the car. If there is too much play, the convergence will be poor and the wheel will meander significantly, while if the play is too little, it will cause hunting and the steering will be constantly turned, which will consume a lot of power energy and cause problems with tire wear. . Therefore, neither state is stable and smooth running. The optimum value of the steering play is determined by the torque and weight balance of the steering system, but the comparison voltage of the sensor to provide this steering play is determined from the relationship between the amount of deviation and the differential output (Figure 3). I'm looking for it. However, in actual sensors, the distance between the sensor and the sign (detection distance) is determined by the unevenness of the road surface, bounce, and
It also changes before and after going up the slope. The differential output of the sensor changes as shown in FIGS. 3(a) to 3(c) when the detection distance changes. However, in the conventional method, the comparison voltage Vref is fixed, and the width of play varies greatly depending on the height of the sensor, as shown in (a') to (a') in Figure 3. This was causing meandering and course roughness.

An object of the present invention is to provide a method for guiding an unmanned vehicle that does not meander or go off course even on rough roads or slopes.

[Means for solving problems]

The present invention detects a guidance sign on the ground from above an unmanned vehicle using two detectors, and the absolute value of the differential output of both detectors exceeds a comparison voltage that changes with the sum output of both detectors. This is a method for guiding an unmanned vehicle, which is characterized by outputting a steering control command when

[Effect]

A guidance sensor for an unmanned vehicle usually has two detection parts to detect a guidance sign, and when the positional relationship between the sensor and the sign is changed, the two detection outputs change according to the curve (a) in Figure 4. )
However, this output is determined by the distance between the sensor and the marker (
As the detection distance h) becomes smaller, it increases as shown in curve (b), and as the detection distance increases, it decreases as shown in curve (c). Therefore, as shown in FIG. 3, the amplitude of the differential output of both detectors becomes smaller as the detection distance increases. on the other hand,
The steering signal is set to turn ON when the sensor deviates from the play width and the absolute value of the differential output exceeds a certain comparison voltage Vref. While the vehicle is running, if the deviation of the sensor from the marker exceeds the play width, the steering power is applied to steer the sensor so that it returns to the play range.

Now, if we pay attention to the sum signal of both detectors, we can see the curve (
As shown in a') to (a'), there is a large change with respect to the detection distance. Therefore, by changing the comparison voltage Vref in conjunction with the increase/decrease in the sum signal due to the change in the height of the sensor, if the sum signal becomes large, the comparison voltage Vref is increased, and if the sum signal becomes small, the comparison voltage Vref is also reduced. , the width of play of the sensor defined by the comparison voltage Vref can be kept almost constant with respect to the slope of the differential output near the center of the marker. In other words, even if the height of the sensor changes, it is possible to always provide the optimum play width for steering and maintain good convergence.

Above, we have described the case where a sensor with two detection parts detects a marker, but the relationships between the sensor and the marker are: a magnetic sensor and a magnetic marker, an induction sensor and a guide cable, and an optical sensor and a light reflector. It can be applied in exactly the same way to a combination with.

〔Example〕

An example in which the method for guiding an unmanned vehicle according to the present invention is applied to a magnetic guidance system using soft magnetic ferrite as a guidance marker will be shown below. As shown in FIG. 1, the magnetic sensor for detecting a labeled object is of the alternating current magnetic field excitation type, and has one excitation coil 1 and two detection coils 3a and 3b, and is constituted by a circuit as shown in the figure. In the figure, the presence or absence of a marker on the ground is detected as a change in induced voltage generated in detection coils 3a and 3b by excitation of an alternating current magnetic field generator 2. The detection signals are rectified by rectifiers 4 and 5 and enter a summation circuit 6 and a differential circuit 7, respectively. The sum signal is input to a comparison voltage generation circuit 8, and the comparison voltage generation circuit 8 provides a comparison voltage Vref proportional to the sum output to a comparison circuit 9. In the comparator circuit 9, when the absolute value of the differential output exceeds the comparison voltage Vref, it becomes High L at TTL.
Output evsl.

When the sensor is located near the center of the dielectric, the differential output is approximately 4 V/■ for the sensor's detection distance of h=10 nm.

It has a deviation width-output characteristic of about 2 V/an when h=20+m+ and about 1.4 V/an when h=30+m. h
The comparison voltage Vref at this time was set to 1v so that the play width when =201TI++ was 10m. on the other hand,
The sum output is 8.4.2.3V at h -40, 20, 30-
By using the value of approximately 174 as the comparison voltage, the play width could be maintained at approximately 10!1111.

An output correction method that can cope with height fluctuations of ±50% using a magnetic sensor has been described above. By using the output processed in this way for steering, it is now possible to drive an unmanned vehicle with good convergence even on rough roads. Although the case where a magnetic sensor is used has been described above, it is of course applicable to an inductive sensor or an optical sensor.

〔Effect of the invention〕

According to the present invention, it is possible to stabilize the running of an unmanned vehicle even on rough roads where fluctuations in the detection distance of the sensor were thought to be unavoidable, and to dramatically improve the reliability of the system. be.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a sensor signal processing device used in the guidance method of the present invention, Fig. 2 is a diagram showing the relationship between the differential output of the voice sensor and the comparison voltage according to the present invention, and Fig. 3 is a diagram showing the difference between the sensors. FIG. 4 is a diagram showing the steering range according to the dynamic output and the conventional comparison voltage, and FIG. 4 is a diagram showing the height change of two detection outputs of the sensor and their sum signal.

Claims (1)

[Claims] (1) Detect the guidance sign on the ground from above the unmanned vehicle using two detectors, and the absolute value of the differential output of both detectors exceeds the comparison voltage that changes with the sum output of both detectors. 1. A method for guiding an unmanned vehicle, the method comprising: outputting a steering control command necessary for driving the unmanned vehicle along a guidance sign when