JPH0418250B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a preview device for a vehicle that uses a heat-sensitive element such as a pyroelectric infrared sensor to detect unevenness on a road surface.

(Prior Art) Recently, certain types of vehicles have been equipped with devices that detect the uneven state of the road surface and control the displacement of the shock absorber. This device uses a so-called vehicle height sensor that detects the height of the road from the bottom of the vehicle by attaching an ultrasonic sensor to the bottom of the vehicle. It is composed of

(Problems to be solved by the invention) However, this vehicle height sensor using ultrasonic waves,
The drawback is that the straight-line propagation of ultrasonic waves is a hindrance, making it impossible to detect uneven conditions in front of the vehicle. For this reason, vehicle height sensors in practical use are installed as far in front of the vehicle as possible, and are configured to perform shock absorber control before the front wheels reach an uneven surface. However, when the vehicle is traveling at high speed,
In the past, there were problems with the front wheels due to unevenness and the addition of steering control.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a vehicle preview device that can reliably detect unevenness in front of a vehicle and can operate stably under various conditions including night and day.

(Means for Solving the Problems) The present invention provides at least two heat-sensitive means disposed at the front of the vehicle in the direction of travel (including forward and reverse).
This is a preview device for a vehicle that detects heat rays emitted from at least two different places on the road ahead in the direction of travel, and detects the condition of the road surface based on the difference in the amount of heat of the heat rays.

(Function) Focusing on the fact that heat rays emitted from flat road surfaces such as asphalt have a continuous distribution, whereas heat rays emitted from uneven road surfaces such as gravel roads have a discontinuous distribution, By detecting heat rays emitted from at least two places on the road ahead and comparing the amount of heat of the heat rays, it is detected whether the road surface is flat or uneven.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Figure 1 shows the circuit of a preview device that uses two dual-type infrared sensors, each with two heat-sensitive means, to detect heat rays emitted from a total of four locations on the road ahead in the direction of travel of the vehicle. A configuration diagram is shown. In the figure, reference numeral 1 denotes a first dual-type infrared sensor, which is composed of two heat-sensitive means, that is, a pair of sensor elements A and B. For example, as shown in FIG. 2, this sensor 1 has a pair of electrodes 12 and 13 formed at a certain distance on one side of a pyroelectric material 11 made of ceramic, single crystal, etc., and an entire surface electrode 14 formed on the other side. and facing electrodes 12,1
A first sensor element A is formed between the two electrodes 13 and 14, and a second sensor element B is formed between the other electrodes 13 and 14. Terminals are attached to the electrodes 12 and 13 to form a series connection type. This dual-type infrared sensor 1 is attached, for example, near the left end of the front bumper of a vehicle, and has, for example, a sensor element A.
sensor element B receives the heat rays emitted from a position 3.01 m in front of the front left tire, and sensor element B receives the heat rays emitted from a position 2.99 m in front of the front left tire. regulated. In this dual-type sensor 1, two sensor elements A and B are connected in series with opposite polarities, so if the amount of heat received by the sensor elements A and B is different, a signal will be generated from the electrodes (terminals) 12 and 13. If the amount of heat received by the sensor elements A and B is the same, no signal will be output from the electrodes 12 and 13. Outputs from the electrodes 12 and 13 are supplied to an amplifier circuit 5 through a MOS transistor 3 serving as a high impedance amplifier. Note that if a dual-type infrared sensor is used as the heat-sensitive means as in this example, the number of sensors required will be halved compared to the case where a single-type infrared sensor is used, resulting in a more compact device and easier manufacturing. becomes easier.

Reference numeral 2 denotes a second dual-type infrared sensor, which, like the first dual-type infrared sensor 1, is composed of two heat-sensitive means, that is, a pair of sensor elements C and D. This dual-type infrared sensor 2 is attached, for example, near the right end of the front bumper of the vehicle, and the sensor element C is located in front of the front right tire.
Sensor element D is placed 2.99m in front of the front right tire so as to receive the heat rays emitted from a position of 3.01m.
The focal point of the mirror is adjusted so that it receives the heat rays emitted from the position. This dual-type sensor 1 has two sensor elements C and D connected in series with opposite polarity.
If the amount of heat received by the hot wire differs, a signal is output,
If the amount of heat received by the sensor elements C and D is the same, no signal will be output. This output is supplied to an amplifier circuit 5 through a MOS transistor 4 serving as a high impedance amplifier.

The amplifier circuit 5 is composed of two operational amplifiers 6 and 7, and the feedback path of the latter operational amplifier 7 includes, for example, Cds.
is inserted. This Cds has a resistance value that changes depending on external brightness and ambient temperature, and the amplification degree of the operational amplifier 7 is adjusted by this resistance change. As a result, an external initial state is set. The output signal from the operational amplifier 7 is the reference potential of the operational amplifier (for example, 1/2 of the power supply voltage Vcc, that is, 1/2
Vcc), and this output signal is output from comparators 8 and 9 which are inversely coupled.
The waveform is shaped. For example, the comparator 8 outputs a negative level signal that is less than the threshold value set by the resistors R ₁ and R ₂ in the same phase, and the comparator 9 outputs a negative level signal that is less than the threshold value set by the resistors R 1 and R ₂ .
A positive signal exceeding the threshold value set by _R4 is inverted and a signal is generated at the output terminal. Therefore, the signals obtained by the comparators 8 and 9 are centered around 1/2Vcc of the input power supply voltage Vcc, and a signal smaller than the threshold signal of the comparator 8 and a signal larger than the threshold signal of the comparator 9 are divided as follows. A double-wave rectified waveform and a pulsed state are obtained at the output terminal Vout of the comparator.

Next, the operation of the preview device according to this embodiment will be explained.

First, the heat rays emanating from the road surface become as shown in FIGS. 3a, b, and c depending on the road surface condition.
Figure a shows a case where the road surface is uneven, such as a gravel road, and the heat rays are emitted in various directions as shown by the arrows, while figure b shows a case where the road surface is flat, such as asphalt, and the heat rays are Figure C shows that the heat rays from the surroundings are reflected on the road surface, and the heat rays are parallel to each other as in Figure B. ing. On the other hand, as shown in FIG. 4, the dual-type sensor 1 has, for example, a heat ray a radiated from a position 3.01 m in front of the front left tire and a heat ray b radiated from a position 2.99 m in front of the front left tire. and received
If the amount of heat between the two is different, that is, when receiving the heat rays emitted from the uneven road surface as shown in FIG. Similarly, the dual sensor 2 receives, for example, a heat ray c emitted from a position 3.01 m in front of the front right tire and a heat ray d emitted from a position 2.99 m in front of the front right tire. If the amount of heat is different, that is, if the heat rays emitted from the uneven road surface as shown in FIG. That is, when a vehicle equipped with this preview device is running and at least one of the road surface in front of the front left tire or the road surface in front of the front right tire becomes uneven, the dual type sensors 1 and 2 are activated. A signal is outputted from one or both of them, supplied to comparators 8 and 9 through an amplifier circuit 5, taken out as a predetermined pulse signal, and subjected to shock absorber control according to the number and width of this pulse signal.

FIG. 5 shows specific output waveforms; FIG. 5a shows the waveform at the output end of the amplifier circuit 5, and FIG. 5b shows the waveform at the output ends of the comparators 8 and 9. In the same figure a, the broken line indicates the operational amplifier 7 and the external condition control element.
The solid line is the output waveform when no CDS is inserted.
The output waveform after correction by inserting Cds is shown.
Further, Vth ₁ is the threshold voltage of the comparator 9, and Vth ₂ is the threshold voltage of the comparator 8. Figure b shows the output waveform after waveform shaping of the comparators 8 and 9, and shock absorber control etc. are applied based on this pulse signal.

In the above embodiment, two dual-type infrared sensors each having two heat-sensitive means are used, and each dual-type infrared sensor detects heat rays at two locations on the road ahead in the direction of travel of the vehicle, a total of four locations. The present invention is configured to output a signal if the amount of heat received by one of the dual-type sensors differs from the heat rays at two locations, thereby detecting unevenness on the road. However, the present invention is limited to this configuration. Instead, a single dual-type sensor may be used to detect the heat rays at two locations (for example, a position 3.01m and a position 2.99m forward from the center of the front of the vehicle in the direction of travel), or two sensors may be used to detect the hot rays. A single type sensor may be used to detect heat rays at two locations. In other words, the gist of the present invention can be achieved if the structure is such that it detects heat rays at at least two locations on the road ahead in the direction of travel, and detects that the road is uneven if there is a difference in the amount of heat between the heat rays. Therefore, it goes without saying that there are various combinations of heat-sensitive means. Further, although a pyroelectric infrared sensor is illustrated as the heat-sensitive element, according to the present invention, a thermocouple or the like may be used.

(Effects) The present invention detects heat rays emitted from the road in front of the vehicle in the direction of travel and detects the condition of the road surface. It is possible to reliably detect irregularities in roads, cracks and holes in asphalt, and even road shoulders, and can apply steering control to the vehicle and issue warnings.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the preview device according to the present invention, FIG. 2 is a sectional view of a dual-type infrared sensor, FIGS. 3 a, b, and c are diagrams showing various heat rays from the road surface, and FIG. The figure shows the state of heat ray detection by the dual-type sensor, and FIGS. 5a and 5b are diagrams showing specific output waveforms. 1 and 2 are dual type sensors, and A, B, C, and D are sensor elements.

Claims (1)

[Scope of Claims] 1. At least two heat-sensitive means are arranged at the front of the vehicle in the direction of travel to detect heat rays emitted from at least two different roads ahead in the direction of travel;
A preview device for a vehicle, characterized in that the condition of a road surface is detected based on the difference in the amount of heat of hot rays. 2. The vehicle preview device according to claim 1, wherein the heat sensitive means is a pyroelectric infrared sensor element. 3. The vehicle preview device according to claim 1, wherein the heat sensitive means is a thermocouple.