JPH04238286A - Method and device for detecting road surface condition to be mounted on vehicle - Google Patents

Abstract

PURPOSE:To give the signal corresponding to largeness of a projection to a suspension before a tire arrives that projection by emitting the ultrasonic pulse to the front-half-down direction with a period, that an acoustic area is continued, to detect the condition of a projection on a road surface. CONSTITUTION:The signal, which is made by a computer processor 7 on the basis of the oscillation frequency of an oscillator 8, is amplified by a transmission power amplifier 3, and ultrasonic wave is emitted from an ultrasonic wave transmitter-receiver 1 to the front-half-down direction of a vehicle through a switch 2 with a period, that a part of area to be emitted is surely overlapped with each other. The ultrasonic wave reflected by the road surface is received by the transmitter-receiver 1, and is amplified by a receiver area amplifier 4 through the switch 2. Furthermore, the signal is detected by an envelope wave detecter 5, and is led to the processor 7 through an A/D converter 6. The processor 7 computes a reflection strength to detect the road surface condition, and the suspension control signal corresponding to an amplitude level of this signal is output from an output terminal 9.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-vehicle road surface condition detection method and device for detecting road surface conditions using ultrasonic waves.

0002

[Prior Art] This type of conventional in-vehicle road surface condition detection device is equipped with a transducer for transmitting and receiving ultrasonic signals at the bottom of the vehicle body, emits ultrasonic pulses directly under the vehicle body, and collects reflected waves from the road surface. By detecting the distance between the vehicle body and the road surface (vehicle height)
There are devices that measure By detecting the vehicle height, this conventional device estimates that, for example, if the vehicle height is a relatively constant value, the road surface is relatively flat, and if the vehicle height changes rapidly, the road surface is rough and uneven. The aim is to control the vehicle's suspension accordingly.

However, in such a device, since the vehicle height is measured in the direction directly below the vehicle body, even if the road surface condition can be detected, it is difficult to control the suspension before the tire runs onto a protrusion on the road surface. , which is almost impossible due to lack of time. Furthermore, when it comes to detecting protrusions on the road surface, it is not directly detected, but rather estimates the road surface condition indirectly from changes in vehicle height, so it is possible to control the suspension according to the road surface condition to make the vehicle more stable. It wasn't good enough to run.

0004

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks, the present invention detects the road surface condition by direct measurement rather than by indirect analogy. In order to achieve this, the height of the protrusion in front of the vehicle is detected.

[0005]

[Means for Solving the Problems] According to the present invention, an ultrasonic pulse is transmitted to the road surface, the reflected ultrasonic signal is received, and an output is applied to the suspension of the vehicle according to the level of the received ultrasonic signal. In an on-vehicle road surface detection system that outputs a control signal, directional ultrasonic pulses are emitted diagonally downward and in front of the vehicle body at a frequency such that the irradiated area partially overlaps, and the reflected and received ultrasonic pulses are There is provided an on-vehicle road surface detection system characterized in that the uneven state of the road surface in front of the vehicle body is detected from the level change of the pulse signal, and an output corresponding to the detected state is outputted as the suspension control signal.

Further, according to the present invention, there is provided an ultrasonic transducer that transmits ultrasonic pulses to the road surface and receives reflected ultrasonic signals, and an ultrasonic wave transducer that transmits an ultrasonic pulse to the road surface and receives an ultrasonic signal reflected from the vehicle. In an in-vehicle road surface detection device including a signal processing device that outputs a signal for controlling a suspension of a vehicle,
The ultrasonic transducer transmits and receives directional ultrasonic pulses at a frequency such that the irradiated area of the road surface always partially overlaps in a diagonal downward direction in front of the vehicle body. When the level of the reflected and received ultrasonic pulse signal temporarily changes to a high value, the signal processing device assumes that there is a protrusion on the road surface at the location where the reflection occurred and responds to this change. An in-vehicle road surface detection device is obtained, characterized in that it is a signal processing device that outputs a suspension control signal based on the suspension control signal.

[0007]

[Embodiment] Fig. 1 is a diagram showing the configuration of an electric circuit used in an embodiment of the present invention, in which 1 is an ultrasonic transducer for transmitting or receiving a sound wave signal, 2 is a transmitting/receiving switch, and 3 is a diagram showing the configuration of an electric circuit used in an embodiment of the present invention. 4 is a receiving band amplifier; 5 is an envelope detector for the received signal; 6 is an analog-to-digital converter (A/D);
7 is a computer processing unit, and 8 is an oscillator that serves as a reference time for all circuits.

In order to operate the apparatus shown in FIG. 1, the waveform shown in a) waveform diagram of FIG. A waveform signal having a carrier wave of frequency f0 for a period of time and a repetition period of T0 is generated. This signal is guided to the transmission power amplifier 3 in FIG. 1, amplified and sent to the ultrasonic transmitter 1 via the switch 2,
), an ultrasonic wave with a beam width θ (spreading angle) is emitted diagonally downward and forward of the vehicle at a center inclination angle α. The emitted sound waves eventually hit the road surface 10, and the reflected waves from the road surface are received by the aforementioned ultrasonic transducer 1, passed through the switching device 2, and amplified by the reception band amplifier 4. Note that H indicates the height of the ultrasonic transducer 1 from the road surface 10.

For example, the output signal of the reception band amplifier 4 is as shown in FIG.
The waveform is as shown in b). In FIG. 2b), ■ indicates the amplified leakage component of the transmitted wave. Also, ■ indicates a reflected wave from the road surface, and the signal amplitude level of the reflected wave is determined by the condition of the road surface. In FIG. 2, the time t0 until the reflected wave from the road surface starts to rise indicates the direct distance between the ultrasonic transducer 1 and the road surface. When there is a protrusion on the road surface, an output waveform as shown in c) of FIG. 2 is obtained, for example. In the figure, ■ indicates an amplitude value that is larger than the reflected signal from the road surface (■) due to the addition of the reflected signal from the protrusion. Note that when there are grooves on the road surface, although not shown in the figure, there is no road reflection in the part marked with ■.

[0010] When the road surface rises in a step-like manner, the condition (■) continues, and as the front wheels ride up and the front of the vehicle becomes higher, it gradually becomes lower. When the rear wheels also ride up and the vehicle body becomes parallel to the road surface, the condition (■) continues. Return to When the road surface descends in a step-like manner, the situation is opposite to the above.

The signal thus obtained is input to the envelope detector 5 in FIG. Here, the output of the envelope detector 7 is as shown in e) of FIG. 2, where ■ is the reflected signal portion from the road surface, and ■ is the reflected signal portion from the protrusion. The amplitude value of (2) is determined by the reflection intensity of the protrusion. d) in FIG. 2 shows a gate signal for removing noise etc. in unnecessary time periods (not shown in FIG. 1), and time G0 is the distance between the ultrasonic transducer 1 and the road surface 10. is made slightly shorter than the time required for an ultrasound signal to propagate back and forth. This reflected signal amplitude is taken into the computer processing unit 7, and the presence or absence of a protrusion, the reflection intensity of the protrusion, and the reflection intensity of the road surface are calculated in the following manner.

As shown in FIG. 3 a), in the present invention, in a region I where the sound waves are emitted once and irradiated onto the road surface, and then in a region II where the sound waves are emitted again and irradiated onto the road surface,
Even at the maximum speed (traveling distance) of the vehicle, it is necessary to ensure that sound waves are irradiated overlapping areas of a certain amount or more, as shown by the dotted lines. Note that A, B, and C are the lower end and center of the sound wave,
The point where the upper end contacts the road surface 10 is shown.

FIG. 4 is a diagram for explaining the sound wave propagation time and the overlapped irradiation (detection) of the road surface by the sound waves, with respect to the above-mentioned means for always generating the overlapped irradiation area. now,
The point at which the sound wave is first emitted (the position of the transducer) is P1.
shall be. Furthermore, as already explained, the points where the lower end and the upper end of the sound wave hit the road surface are expressed as A0 and C0. The sound wave emitted at point P1 is reflected by the road surface 9 and returns, but since the vehicle is traveling at a certain speed, the position of the transducer when receiving the reflected wave is P1'. The next sound wave will be emitted after time T0 has elapsed, but the transducer position at that time is P2.
The point where the lower and upper ends of the sound wave hit the road surface is A1,
Let it be C1. Also, as before, the position of the transducer that receives the reflected wave from the road surface is assumed to be P2.

At this time, if the sound wave propagation distance is d2 between P1 A0, d1 is between P1 C0, d1' is between P1'C0, d2 is between P2 A1, and d2' is between P2'A1, the maximum sound wave propagation distance is d1 +d1
', and the minimum sound wave propagation distance is d2 +d2'. In order to generate an overlapping area, the following equation 1 needs to be satisfied. Here, C represents the speed of sound, D represents the propagation distance between P1 and P2, and V represents the maximum vehicle speed. Then, the spread of the sound wave θ (directivity) satisfies this number 1.
, the transmission period T0 of the sound wave, the central inclination angle α of the sound wave, the transmission pulse width Tx, the gate width W, and other constants are determined.

[0015]

[Math 1]

The road surface condition in front of the vehicle is detected from these values, and a suspension control signal corresponding to this signal amplitude level is output from the output terminal 9 in FIG. The damping of the suspension is controlled to be hard or soft using a pneumatic system or other means.

Furthermore, by detecting the signal amplitude level from the road surface shown by ■ in FIG. 2 and averaging the time domain an appropriate number of times, it is possible to detect the reflection intensity of the road surface itself, and from this signal value Needless to say, it is also possible to control the suspension according to road conditions. At this time, TVG (Tim
The accuracy can be further increased by performing correction such as eVariable gain).

[0018]

[Effects of the Invention] As explained above, according to the method of the present invention,
By emitting ultrasonic pulses diagonally downward and in front of the vehicle body at a frequency that ensures that the sound wave area that illuminates the road surface is not interrupted, it is possible to detect any protrusions on the road surface in front of the vehicle. Since a signal corresponding to the size of the protrusion (the magnitude of the reflection intensity of the protrusion) can be given to the suspension before the tire reaches the protrusion, suspension damping for comfortable driving can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an electric circuit used in an embodiment of the method of the present invention.

FIG. 2 is a waveform diagram of a sound wave for explaining the method of the present invention.

FIG. 3 is a diagram for explaining the spread of sound waves in the embodiment of the present invention.

FIG. 4 is an explanatory diagram for explaining sound wave propagation time and overlapping irradiation (detection) of a road surface by sound waves.

[Explanation of symbols]

1 Ultrasonic transducer 2 Transmission/reception switch 3 Transmission power amplifier 4 Receive band amplifier 5 Envelope detector 6 A/D converter 7 Arithmetic processor 8 Oscillator 9 Output terminal 10 Road surface

Claims (2)

[Claims] Claim 1: An in-vehicle road surface probe that transmits ultrasonic pulses to the road surface, receives reflected ultrasonic signals, and outputs an output according to the level of the received ultrasonic signals as a signal for controlling the suspension of a vehicle. In this method, directional ultrasonic pulses are emitted diagonally downward and in front of the car body at a frequency such that the irradiated area partially overlaps, and the level change of the reflected and received ultrasonic pulse signal is used to detect the road surface in front of the car body. 1. An in-vehicle road surface detection system, characterized in that an uneven state of a vehicle is detected, and an output corresponding to the detected state is outputted as the suspension control signal. [Claim 2] An ultrasonic transducer that transmits ultrasonic pulses to the road surface and receives reflected ultrasonic signals, and controls the suspension of the vehicle to output according to the level of the received ultrasonic signals. In the in-vehicle road surface detection device that includes a signal processing device that outputs a signal, the ultrasonic transducer transmits directional, periodic ultrasonic pulses to the road surface in a diagonal downward direction in front of the vehicle body. This is an ultrasonic transducer that emits at a frequency such that the irradiation areas always partially overlap, and when the signal processing device detects that the level of the reflected and received ultrasonic pulse signal temporarily changes to a high value. An in-vehicle road surface detection device is characterized in that it is a signal processing device that outputs a suspension control signal corresponding to a change in the presence of a protrusion on the road surface at a position where reflection occurs.