JPS63118678A - Road information detection device - Google Patents

Abstract

PURPOSE:To obtain the roughness of a road surface, the ground speed, the distance to a preceding car, and the relative speed by providing a microwave transmitting and receiving part, a signal processing part, etc. CONSTITUTION:A microwave transmitting and receiving part 1 consists of a microwave circuit 11, an antenna circuit 12, and a receiving circuit 13. The microwave FM-modulated by the circuit 11 is radiated by the circuit 12, and the microwave reflected back from a reflector is received to take out a beat signal by the circuit 11, and the beat signal is amplified by the circuit 13 and is supplied to a signal processing part 2. Meanwhile, the beat signal is divided to a distance detecting circuit 23 and a speed detecting circuit 24 in the processing part 2 and is digitized after analog processing and is sent to an operating circuit 22. Distance information and amplitude information are taken out in the circuit 22, and distance operation and roughness operation are performed in the circuit 22. The signal obtained in the circuit 24 is used to perform speed operation in the circuit 22. Thus, the roughness of the road surface, the ground speed, the distance to a preceding car, etc., are obtained.

Description

[Detailed Description of the Invention] (Industrial Application Field) The invention is to detect road surface roughness or ground speed using FM-CW radar and obtain road surface information necessary for automobile suspension control and anti-skid brakes. output,
The present invention also relates to a device that outputs distance and relative speed to a preceding vehicle, particularly forward information necessary for slow driving.

(Prior art) Conventionally, devices in this field include long-range collision prevention radar,
There are close range radars, ground radars, etc., and their transmission sources are ultrasonic waves, microwaves, millimeters, or light. Among these, the main short-range radar related to the present invention was mainly developed as a predictive sensor for air (gas) packs, and is intended to protect human life in the event of a vehicle collision.

Furthermore, in recent years, vehicle comfort and anti-slip measures have become issues, and electronically controlled suspensions have been commercialized for the former, and anti-skid brakes or anti-lock brakes for the latter.

(Problems to be Solved by the Invention) In terms of performance, the above-mentioned close-range radar only needs to be able to detect a relative distance of 2 m or more and a relative speed of 30 krv' (relative speed of 30 krv').
There was a limit to its widespread use as a close-range radar.

Also,! Sub-control suspension uses passive elements such as G-sensors (acceleration sensors) to detect road roughness, and operates after an impact to electronically control the damping force of the suspension, improving ride comfort. has its limits. Anti-skid brakes have independent rotary speed sensors on two or four wheels, and detect the difference in the rotation speed of each wheel and control the braking of each wheel to compensate for it, so the ground speed This is different from controlling the wheels by detecting the discrepancy between the number of rotations of the wheels and the number of revolutions of the wheels.This is not a measure to prevent vehicle slippage in the strict sense of the word.

As an improvement to the electronically controlled suspension mentioned earlier,
The applicant disclosed a technology for actively detecting road surface roughness and controlling the suspension in Patent Application No. 61-162598, but did not mention anti-skid brake control or the like.

(Means for Solving the Problems) In order to solve these drawbacks, the present invention provides means for obtaining the roughness of the road surface, ground speed, distance to the preceding vehicle, and relative speed. For this purpose, we installed a microtransmission/reception unit on the front of the vehicle that can direct the radiation beam diagonally downwards and almost horizontally.
It emits microwaves forward and downward, captures the reflected waves and beats from the road surface, and processes these beat signals to detect road surface roughness and ground speed. Then, if necessary, the microphone 0's radiation direction is switched to the horizontal direction to encourage the preceding vehicle by 3M, and the beat signal with the reflected wave from the preceding vehicle is processed to provide clear information on the front, such as inter-vehicle distance and relative speed. This is what I did to get it. The transmitting microwave is an FM waveform that has been subjected to FM during a part of the sweep cycle.
It is an M-CW method, and distance information is transmitted from the FM part.

I have received news from the CW section. Examples will be described in detail below with reference to the drawings.

(Embodiment) FIG. 1 is a basic configuration diagram of an embodiment of the present invention, which consists of a microwave transmitting/receiving unit 1 and a signal processing unit 2. Micro transmission/reception fM11 includes microphone O wave circuit 11. Antenna circuit 12. The receiving circuit 13 is configured as follows, and the microwave FM modulated by the microwave circuit 11 is transmitted to the antenna circuit 1.
The microwave radiated at 1 and returned from the reflecting object 2 is received, a beat signal is extracted at several times 11, and the beat signal is amplified by the receiving circuit 13 and supplied to the signal processing section 2. In the signal processing section 2, this beat signal is sent to the distance detection circuit 2.
3 and a speed detection circuit 24, and after analog processing, it is digitized and sent to the arithmetic circuit 22. Distance detection circuit 23
Then, the distance information and amplitude information are extracted, and the arithmetic circuit 22 calculates the
Perform distance and roughness calculations. Speed detection times at 4 o'clock @2
The signal obtained from step 4 is used to perform speed calculation in the calculation circuit 22. In addition to the above, the signal processing section 2 includes a sweep generation circuit 21 that generates a reference clock signal to the arithmetic circuit 22 and a sweep signal for FM modulating the microwave in the microwave transceiver section 1.

Next, the operation will be explained with reference to the detailed block diagram shown in FIG. 2. The microwave transmitter/receiver ml continuously oscillates FM-modulated microwaves from the microwave circuit 101.

The signal is sent through the coupler 102 to the transmitting antenna 103 of the antenna circuit 12. The antenna circuit @12 consists of the transmitting antenna 103 and the receiving antenna 104, as shown in Fig. 3 (
As shown, there is a patch type printed antenna on two plates separated by a partition plate 108. The antenna circuit 12 is installed at the front bumper of the car as shown in Figure 3, at a height of about 45 cm from the road surface.

When obtaining road surface information, the incident angle to the road surface is set to tJ7.
5 degrees by a mechanical or electronic switching means, and when obtaining forward information, switch to parallel to the road surface (a, b in Fig. 3C). When obtaining road surface information.

This mounting position allows you to distinguish between the 2w5 surface and other targets.

This is the optimum positional dimension that is less affected by unique perturbations and allows identification of road surface roughness. Next, the Micro Hanha reflected from the road surface or the car in front.

It is received by the receiving antenna 104, sent to the mixer circuit 105, mixed with the transmitted signal obtained by the combiner 102, and converted into a beat signal fP. The beat signal is passed through a low pass filter (LPF) 106 and a low noise amplification circuit Er107.
It can be amplified by As shown in FIG. 3, the micro transmitting/receiving section 1 has the above-mentioned antenna circuit w! It has a structure in which a microwave circuit 11 and a receiving circuit 13 are built into the a side of r12,
The microwave circuit 11 is a microwave IC, and the receiving circuit 13
is obtained using high print IC.

Next, the signal processing section 2 has one function as a sweep voltage generation circuit 21.
．． Arithmetic circuit 22. Distance detection circuit 23 and speed detection circuit 2
It can be roughly divided into 4.

As shown in FIG. 4, the sweep voltage generation circuit 21 divides the clock signal generated from the reference clock generation circuit 201 using a frequency dividing circuit I202 (FIG. 4A) to determine the sweep period. This sweep period signal is a sweep)
IJ circuit 2o32 frequency divider circuit ■205 monopulse circuit 2
06. and is sent to the step sweep generation circuit 207. The sweep trigger circuit 203 generates a sweep trigger, and the sweep generation circuit 204 generates a sweep voltage (see Figure 4). This sweep voltage is.

The amount of response of the varactor diode of the oscillator 101 varies, and the oscillator 101 is FM modulated. The frequency dividing circuit 11205 outputs a signal that determines the step sweep period of the step sweep generation time 1207.
．． It is decided by the signal of 202. Figure 4 (e). The monopulse circuit 206 generates a sample signal for the speed detection circuit 24 (see FIG. 4 2).

On the other hand, the beat signal amplified by the low noise amplifier circuit 107 of the micro anti-transmission/reception section 1 is passed through a high-pass filter (HPF).
208 and LPF 218, the signals are separated into a distance detection circuit 23 and a speed detection circuit 24, respectively.

The beat signal (FIG. 4) that has passed through the HPF 208 whose cutoff frequency is set to the beat frequency (fbmin) corresponding to the shortest detection distance is amplified by the low-noise amplifier circuit 209 and sent to the mixer circuit 201.

This beat signal is up-converted by a mixer circuit 210 to an output signal of a local oscillator 211 which is FMfi-tuned by the output voltage of a step sweep generation circuit 207, and is supplied to a band pass filter (BPF) 212. The center frequency of BPF212 is.

The maximum frequency of the local oscillator 211 (FLRNA and FBM
The frequency of the sum of in (f 1max −1−fbmin
), and the band = is the distance #l! The beat frequency width is set to correspond to the accuracy. BPF212
The Yoji Attendant No. is amplified by the amplifier circuit 212, and the peak value is detected! At 214, the peak open voltage (p-p voltage value) can be maintained (Fig. 4), and the monopulse circuit 206
It is reset 11 with the sample signal. This output signal is A
The signal is converted into a digital signal by the /D converter 215 and input to the CPU 217 via the latch circuit 216. At the same time, a counter output from the step sweep generation circuit 207 indicating the number of sweep cycles within the step sweep cycle is input to the CPU 217 as roughness or distance information via the latch circuit 216.

On the other hand, the cutoff frequency of the LPF 218 of the speed detection circuit 24 is set so as to extract the beat frequency due to the Doppler effect. The beat signal extracted by LPF218 is
It is amplified by the amplifier circuit 219, and the sample and hold circuit 22
The sample signal synchronized with the sweep period at 0 is sampled and held (see Fig. 4), and the shaping circuit 221
After that, it is converted into a pulse in the pulse forming step M222 (Fig. 4). In order to find the period of the obtained pulse signal, it is supplied to the counter circuit 223 and divided by two frequency divider circuit I2.
02 signal is used as a clock, and is reset by the output signal of the pulse shaping circuit 222.

The binary signal received by the counter circuit 223 is as follows.

Through the latch circuit 216, the speed information is sent to the CPU 217.
is input.

The arithmetic circuit 22 includes a latch circuit 216 and a CPU 217. The CPU 217 U uses the clock signal of the reference clock generation circuit 201 as a system clock. When switched to forward information, the beat signal digitized by the A/D converter 215 is sent to the CPU 2
The levels are compared in step 17, and the beat frequency at the maximum level is determined from the counter output from the step sweep generating circuit 207 (FIG. 5A). This counter output is CP
The distance is calculated in U217, and the CPU 217 outputs it as an interrogation distance signal. At the same time, the relative speed with respect to the preceding vehicle is calculated from the binary signal obtained by the counter circuit 223.
The speed is calculated by the CPU 217 and output. Next time the road surface information is switched, the beat frequency from the road surface (1rP
-2m) is fixed, so the step sweep generation circuit 207 shortens the step sweep cycle as shown in FIG. 5 by the switching signal. The step sweep voltage is set to fP such that a local oscillation mantissa corresponding to the beat frequency from the road surface is obtained (see Figure 5).

At this time, the output signal of the A/D converter 215 is
17, the levels are compared, and the maximum level is stored, averaged every step sweep period, roughness is calculated, and is output from the CPU as a rough symbol.

Further, the signal inputted to the CPU 217 as speed information is calculated in the same manner as the calculation of the relative speed with respect to the preceding vehicle.

It is output from the CPU 217 as a ground speed signal.

The signals of roughness, ground speed, inter-vehicle distance to the preceding vehicle, and relative speed obtained in this way are respectively sent to the controlled circuit.

(Effects of the Invention) As explained above, by using the device of the present invention as a vehicle sensor, an active method of detecting road surface conditions is possible. Ground speed can be measured even with anti-skid brakes.

This allows for more practical brake control. In addition, by switching to forward information detection, the inter-vehicle distance and relative speed to the preceding vehicle can be measured in real time, making inter-vehicle control possible in combination with an autotransmission, and increasing fuel efficiency.

It can reduce the burden on humans, especially during traffic jams, and when combined with cruise control at high speeds, it directs fully visual driving.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram of an embodiment of the present invention, Fig. 2 is a detailed block diagram of the embodiment, Fig. 3 is an explanatory diagram of the installation of the micro temporary transmitter/receiver and packing operation, and Fig. 4 is the output of each circuit. FIG. 5 is a comparison diagram of step sweep voltage forward information and road surface information. 1...Micro-Saka transceiver unit, 2...Signal processing unit. 11...Micro circuit, 12...Antenna circuit,
13... Receiving circuit, 21... Sweep voltage benthic circuit, 22... Arithmetic circuit, 23... Distance detection circuit, 24
...Speed detection circuit.

Claims (2)

[Claims] (1) Transmitting and receiving microwaves that are FM modulated using a sweep signal generated by a sweep voltage generation circuit, extracting the beat signal between the transmitted signal and the received signal, and identifying only the beat signal from the target object. and a signal processing section that receives and processes a beat signal from the microwave transmitting/receiving section to obtain information on a target object, wherein the microwave is transmitted during a part of the period of the sweep voltage. It transmits and receives microwaves using FM-CW method, which is FM modulated and the other part is CW, and separates the signal corresponding to the Doppler frequency from the beat signal generated by the transmitted and received signals to calculate the ground speed or relative speed with the preceding vehicle. and a means for extracting a time-domain signal corresponding to the FM modulation to obtain road surface roughness or a distance to a preceding vehicle in the signal processing section. (2) The microwave transmitter/receiver is attached to the front of the vehicle, and the microwave transmitter/receiver is fixed at an angle suitable for detecting a road surface or a preceding vehicle by means of a switching means. Road information detection device.