JPS612089A - Obstacle detecting sensor - Google Patents

Abstract

PURPOSE:To detect an obstacle against a moving substance having selftravelling ability by arranging the 1st and 2nd sensing plates, a high frequency oscillator and a switching circuit on an opposite part to the obstacle and using the change of stray capacity, resistance loss, etc. generated between the obstacle and the sensor. CONSTITUTION:The sensor is constituted of the 1st sensing plate 2, the 2nd sensing plate 3 arranged in parallel with the plate 2, the high frequency oscillator 1 and the switching circuit 6 which are connected to both the sensing plates 2, 3. The sensing plate 2 is functioned as an antenna. In an automatic restoration type amplifier part, a level signal outputted from the oscillator 1 is inputted to the non-inverted input terminal of a DC amplifier part 61, a capacitor C8 is connected to its inverted input terminal through a resistor R5 and an output from the amplifier part 61 is applied to a node between the capacitor C8 and the resistor R5 through a diode D2. On the other hand, a voltage from a variable resistor R7 is applied to one input of a comparator 62 as a reference one and the output of the comparator 62 is inputted to the base of a transistor Q2.

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention relates to an obstacle detection sensor for avoiding collisions with obstacles in moving objects capable of self-propulsion such as automatic trolleys and mobile robots. .

(Technical background of the invention and its problems) Obstacle detection sensors that prevent self-propelled moving objects from colliding with obstacles have conventionally used light or ultrasonic waves. be. The principle of an obstacle detection sensor that uses light is to detect the light emitted from a light emitting part such as a light emitting diode and reflected back from an obstacle using a light receiving sensor such as a photodiode. Obstacle detection sensors that use this light have the disadvantage that their operation is extremely unstable because the amount of reflected light varies greatly depending on the color of the obstacle.

- On the other hand, the principle of an obstacle detection sensor using ultrasonic waves is
The distance between the obstacle and the main body of the moving object is detected by measuring the time difference between when the ultrasonic waves emitted from the ultrasonic generator reflect off the obstacle and return. Obstacle detection sensors that use ultrasonic waves may malfunction by detecting ultrasonic waves that exist in the environment, and are highly directional, so the detection range of obstacles is narrow with just one obstacle detection sensor. There are some problems. In addition, if multiple obstacle detection sensors are installed in order to eliminate the directivity defect and their obstacle detection ranges overlap, there is a possibility of false detection due to interference between the obstacle detection sensors. This results in the disadvantage of increased Furthermore, as a principle of an obstacle detection sensor using ultrasonic waves, it is possible to use the Doppler effect, but this has the drawback of not being versatile because it depends on the speed of the obstacle and the moving object itself.

(Object of the invention) This invention was made under the above circumstances,
The aim is to provide an obstacle detection sensor that is optimal for moving objects with self-propelled ability, by utilizing changes in stray capacitance and resistance loss between obstacles, without using light or ultrasonic waves.

(Summary of the Invention) The present invention relates to an obstacle detection sensor that utilizes changes in stray capacitance and resistance loss between the obstacle and the obstacle, and the present invention relates to an obstacle detection sensor that utilizes changes in stray capacitance and resistance loss between the obstacle and the obstacle. , a second sensing plate installed parallel to the first sensing plate, a high frequency oscillation circuit connected to the first and second sensing plates, and an output of the high frequency oscillation circuit. 1st and 2nd above
and a switch circuit for detecting the presence or absence of the above-mentioned obstacle based on the output relationship of the sensing plate.

(Embodiments of the Invention) First, to explain the principle of the oscillation circuit and switch circuit used in the present invention, as shown in FIG. 2 sensing plate 3
These two sensing plates 2 and 3 are used as part of an antenna for radio wave radiation, and high-frequency oscillation (for example, 1 ~20MHz) circuit l, and an automatic reset type switch circuit 6 connected to the high frequency oscillation circuit l and the sensing plates 2 and 3 for detecting the output level of this high frequency oscillation circuit l and controlling the controlled object. It consists of The high frequency oscillation circuit 1 is, for example, a Colpitts type oscillation circuit, and the distance between the two sensing plates 2 and 3 is constant (for example, 15+o+s), and the oscillation circuit 1 and the switch circuit 6
Even if the oscillator is placed at an arbitrary location, there will be no significant difference in the oscillation conditions.

Here, the sensing plate 2 on the non-grounded side functions as an antenna for radio wave radiation.

The switch circuit 6 is made up of an automatic reset type amplifier section and a comparator section. A capacitor C8 is connected to the inverting input terminal via a resistor R5, and the output v0 of the DC amplifier 81
is input to one side of the comparator 62, and the resistance R
6 to the inverting input terminal, and the diode I]2 to the connection point between the capacitor C8 and the resistor R5. Further, the voltage from the variable resistor R7 is given to the other side of the comparator 82 as a reference.
The output of the comparator 62 is input to the base of the transistor Q2 via a resistor R8, and the excitation winding RY of the relay is connected to the collector of the transistor Q2 together with a surge absorbing diode D3.

Here, the equivalent circuit of FIG. 1 becomes as shown in FIG. 2, and the oscillation circuit 1 has a frequency f due to the resonance of the capacitor Go and the inductance L0. It reaches its maximum level at , and is made up of, for example, a Colpitts-type oscillation circuit. On the other hand, the sensing section consisting of sensing plates 2 and 3 connected to this oscillation system is
The apparent capacitor C2 and the inductance L of the induction coil 4 form a resonant circuit, and the relationship between the oscillation frequency f1 and the resonant frequency fo is as shown in FIG. Keep it a little higher. Then, when a guiding object such as a person approaches or contacts the sensing part, the resonance frequency f becomes the oscillation frequency f. When approaching , it is a tank circuit whose Q (voltage increase ratio in the resonant circuit) is also lowered by the human body, etc., so the Q is dumped by the resonant frequency f1, and the peak value P1 of the oscillation frequency f0 decreases in level to P2.

Therefore, by detecting a decrease in the level of the oscillation output Vout from Pi to P2 using the switch circuit 6, it is possible to detect the approach of a person or the like to the sensing plate 2. In addition, L
The description above shows a case where the resonant frequency f1 of the sensing section is higher than the oscillation frequency f0 of the oscillation circuit l. In the case of X, one oscillation output is Vo
As shown in FIG. 4, ut increases from Pl to P3.

Such an upward change in the oscillation output Vout can also be detected by a similar switch circuit.

On the other hand, in the above example, the high frequency oscillation circuit l is connected to the sensing plates 2 and 3.
Although it is possible to connect directly with a conductive wire, it is also possible to connect with a feeder such as a coaxial cable. Fig. 5 shows an example of connection using a coaxial cable 5. The coaxial cable 5 is used as a capacitor C3 component, and the capacitance (C2 + C3) is formed with C2 of the sensing plates 2 and 3. and the inductance 1 of the induction coil 4 constitute a resonant circuit. With such a connection of the coaxial cable 5, it is also possible to detect the approach of a person or the like to the sensing section by detecting the level change of the oscillation frequency fO described above. In addition, Fig. 6 shows the guide 3411
This is an example of forming a resonant circuit using coupling of capacitor C4 instead of electromagnetic induction.
The resonance frequency fI is determined by the capacitor C2, the inductance L+, and the capacitor C4 connected in series.

Incidentally, in the above description, the change in the level of the output Vout of the resonant circuit l is detected by the switch circuit 6, but for example, it is detected by phase detection that the resonant frequency f1 moves toward the oscillation frequency fO side in FIG. Also, sensing plate 2
The approach of the derivative to can be detected. FIG. 7 shows one embodiment of the invention, in which the oscillation output of the oscillation circuit 1 is supplied to the sensing plate 2.3 via the coaxial cable 5 by the induction coil 7, and the oscillation output of the oscillation circuit 1 is supplied to the sensing plate 2.3 via the coaxial cable 5. It is input to transistor Q6 as one of the multiplicand values. Note that the coaxial cable 5 may be omitted. The frequency signals from the sensing plates 2 and 3 are input as differential signals to two transistors Q4 and C5 of a multiplier 8 via an induction coil 7. Further, a variable capacitor C5 for frequency adjustment is connected in parallel to the induction coil 7, and by adjusting the capacitance of the variable capacitor C5, a resonance frequency f1 having no phase difference with the resonance frequency fo is generated between the induction coil 7 and the sensing section. It is now possible to obtain In this way, when the oscillation frequency fO of the oscillation circuit 1 and the resonance frequency 11 formed by the sensing section are input to the differential amplification type multiplier 8, the change in the phase difference of the image frequency signal is It is obtained from the collector output, and by inputting this to the switch circuit 6 described above, it is possible to detect the approach of a person or the like to the sensing section.

In this invention, the above-described oscillation circuit and switch circuit are mounted on a moving object such as a mobile robot capable of self-propelled movement, and FIG. 8 is an external view showing an example thereof. 10 is configured to travel in the M direction on wheels 12 in accordance with commands received via an antenna 11, and is provided with a working arm 13 at its top that can rotate and extend/contract. Since the moving object 1O travels automatically, it must absolutely avoid collisions with workers, fixed objects, pillars, etc. For this purpose, a sensor 20 that operates on the principle described above is installed on the front side. The external configuration is as shown in FIG. 9, for example. That is, two sensing plates 21 and 22 bent into a U-shape are arranged in parallel with an insulator 23 in between. (or the rear surface). The sensing plates 21 and 22 do not necessarily have to be bent into a U-shape, but when the moving object 10 automatically travels while changing direction as in this example, it is possible to detect obstacles diagonally ahead. can be detected. Therefore, if the vehicle only travels straight, it may be configured with two straight flat plates. and,
The sensing plates 21 and 22 correspond to the aforementioned sensing plates 2 and 3, respectively, and the aforementioned oscillation circuit 1 is connected to the sensing plates 21 and 22.
and a switch circuit 6 are connected to the feeder or directly. Further, in this example, in order to improve the sensitivity to the outside (front), the area (width) of the outside sensing plate 21 is made smaller than the area (width) of the inside sensing plate 22.

In such a configuration, if the moving object 10 does not encounter an obstacle, the built-in oscillation circuit l maintains a normal output level or phase difference, and this is transmitted to the switch circuit 6 to turn the relay contact off (or on). The moving object IO can be moved by operating its drive circuit. However, when the moving object 10 approaches an obstacle while moving, the frequency of the oscillation circuit 1 changes due to stray capacitance and resistance loss between the obstacle and the sensing plates 21 and 22, and the output changes according to the change in Q. Level and frequency change. and,
As described above, this change in output level and frequency is transmitted to the switch circuit 6, the relay contact is turned on (or off), the drive circuit is deactivated, and the moving object 10 is stopped. When the obstacle is removed, the output level and frequency of the oscillation circuit 1 return to normal levels, so the relay contact is turned on (or off) in the switch circuit 6 as described above.
The moving object 10 then operates its drive circuit and starts moving again.

- On the other hand, if the obstruction is not removed, the output level and frequency of the oscillation circuit 1 will continue to decrease (increase), but the switch circuit 6 is of an automatic reset type, and as mentioned above, the capacitor Even in a state where the discharge gradually occurs and the output level of the oscillation circuit l has decreased, the relay contact is turned on (or off) and the moving object lO resumes movement. Then, moving object 1
Since moving object 0 approaches the obstacle further, the output level of oscillation circuit 1 also decreases (or increases) by that amount, and this is transmitted to switch circuit 6, which turns on (or turns off) the relay contact and stops moving object 10. If the obstacle is a stationary object that cannot be removed, the moving object 10 starts moving again due to the automatic return action of the switch circuit 6, and then stops.

It moves repeatedly and eventually comes into contact with an obstacle.

Therefore, in order to avoid such a situation, moving objects
If the number of stops of the moving object 10 is counted and the stop and movement of the tool is repeated a certain number of times, the moving circuit of the moving object 10 may be turned off by a switch means provided separately.

Here, when the sensing distance of the sensor 20 with respect to obstacles was determined through experiments, it was found that it was approximately 30 to 30 degrees for humans, metals, and animals.
After setting it to sense at 40cm, it senses at about 30C11 on a concrete acid pillar, and at about 3C on a concrete wall.
It was found that it can be sensed at 0cn+, and for rubber tires it can be sensed at about 20cm. It was also confirmed that synthetic resin boxes and the like can be detected at a distance of 3 to 4 cm, although this varies depending on the degree of high-frequency insulation.

Note that the shape of the sensing plate of the sensor 20 may be bent into an arc-shaped sensing plate 24, 25 as shown in FIG. . In short, it is sufficient to arrange two sensing plates in parallel.

(Effects of the Invention) As described above, according to the obstacle detection sensor of the present invention, obstacles such as people and objects can be reliably detected with a relatively simple configuration, and the detection accuracy is not influenced by the environment. There are advantages. Furthermore, the shape of the sensing plate can be matched to the shape of a moving object, making it possible to detect obstacles over a wide range.

[Brief explanation of the drawing]

Fig. 1 is a wiring diagram showing a circuit example of a sensor used in this invention, Fig. 2 is an equivalent circuit diagram for explaining the principle of operation of this invention, and Figs. 3 and 4 are diagrams for explaining its operation. Figures 5 to 7 are wiring diagrams showing other embodiments of the invention, Figure 8 is an external view of a moving object showing an embodiment of the invention, and Figures 9 and 1O are respectively FIG. 3 is a diagram showing an example of the structure of a sensing plate of the present invention. 1... High frequency oscillation circuit, 2, 3, 21, 22, 24.
25... Sensing plate, 4... Induction coil, 5... Coaxial cable, 6... Switch circuit, 10... Moving object,
20...Sensor. Figure 4 Figure 9 Figure 5 Figure 6

Claims (1)

[Scope of Claims] A first sensing plate installed at a portion facing the obstacle of a moving object, and a second sensing plate installed with a distance between the first sensing plate and the first sensing plate being kept parallel to each other; a high-frequency oscillation circuit connected to the first and second sensing plates; and a switch circuit for detecting the presence or absence of the obstacle based on the relationship between the output of the high-frequency oscillation circuit and the output of the first and second sensing plates. An obstacle detection sensor comprising: