JP3314005B2 - Abnormality detection method of vehicle speed sensor in inter-vehicle distance warning system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an abnormality of a vehicle speed sensor in an inter-vehicle distance warning system which issues a warning when the inter-vehicle distance is short.

[0002]

2. Description of the Related Art An inter-vehicle distance alarm system which issues an alarm when the inter-vehicle distance from a vehicle traveling in front is short, and performs brake control as necessary, detects the own vehicle speed. The vehicle speed information obtained by the vehicle speed sensor is very important in determining the timing of the warning.

In such an inter-vehicle distance alarm system, when an abnormality such as disconnection or short-circuit occurs in the vehicle speed sensor, no alarm is issued even though the inter-vehicle distance is approaching a level at which an alarm should be issued. Therefore, it is necessary to accurately detect such an abnormality of the vehicle speed sensor.

Conventionally, it has been considered to detect abnormality of a vehicle speed sensor in combination with another system. This is, for example, combined with a navigation system mounted on a vehicle, and is derived by the navigation system based on received radio waves. In the case where the vehicle position is changed but the warning is not issued because the output signal of the vehicle speed sensor is not input in the following distance warning system, it is determined that the vehicle speed sensor is abnormal. .

However, according to the combination with other systems such as a navigation system, there is a problem that a very large system is required for detecting an abnormality of a vehicle speed sensor used in an inter-vehicle distance warning system. It is desired that the inter-vehicle distance warning system itself detects an abnormality of the vehicle speed sensor without using another system.

An object of the present invention is to make it possible to accurately detect an abnormality of a vehicle speed sensor with a simple configuration.

[0007]

According to a first aspect of the present invention, there is provided a vehicle speed sensor for detecting an own vehicle speed, a measuring unit for measuring an inter-vehicle distance between the own vehicle and a preceding vehicle traveling ahead, and the vehicle speed sensor. Command means for judging whether or not the inter-vehicle distance to the preceding vehicle has approached the alarm level at the current vehicle speed from the output signal and the measurement value of the measuring means, and outputting an alarm command signal when approaching, An inter-vehicle distance alarm system including an alarm unit that operates in response to the alarm command signal to issue an alarm, wherein a state in which the output speed of the vehicle speed sensor is not provided and the relative speed of the preceding vehicle to the own vehicle is equal to or higher than a predetermined speed is maintained for a predetermined time It is characterized in that it is determined whether or not to continue, and when the vehicle continues for a predetermined time, it is determined that the vehicle speed sensor is abnormal.

According to such a configuration, when there is no output signal from the vehicle speed sensor and the state in which the relative speed with respect to the preceding vehicle is equal to or higher than the predetermined speed continues for a predetermined time, it is determined that the vehicle speed sensor is abnormal. An abnormality of the vehicle speed sensor can be accurately detected with a simple configuration without using another system such as a navigation system as in the related art.

At this time, if the vehicle speed sensor is determined to be abnormal as described in claim 2, if the abnormality is notified by the notifying means, the driver or the like can easily detect the abnormality of the vehicle speed sensor. It becomes possible to know.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. 1 is a block diagram showing the overall configuration, FIG. 2 is a detailed functional block diagram of a part of FIG. 1, and FIG. 3 is a flowchart for explaining the operation.

First, FIG. 1 showing the configuration of the entire system will be described. In FIG.
Reference numeral 2 denotes a scanning laser radar, which is a measuring means composed of a semiconductor laser or the like. The reflection angle of the laser beam is changed by a mirror that is rotated by a predetermined angle such as 1 ° by, for example, a stepping motor. A laser beam scanned in a predetermined direction is irradiated on a forward vehicle, and a light receiving element (not shown) such as a phototransistor built in the scan laser radar 2 is scanned.
Receives the reflected light from the vehicle ahead and outputs a received light signal to a control computer (hereinafter referred to as a control CPU) 3. The time from when the control CPU 3 irradiates the laser beam at each irradiation point to when the reflected light is received. Then, the inter-vehicle distance from the own vehicle to the preceding vehicle is calculated based on the speed of light and the light speed.

The control CPU 3 also has a function as a command means, and derives a relative speed V of the preceding vehicle with respect to the own vehicle from the temporal change of the calculated inter-vehicle distance. Moreover, it is determined whether or not the inter-vehicle distance to the preceding vehicle has approached the alarm level at the current vehicle speed, and when approaching, an alarm command signal is output to alarm means described later.

Further, in FIG. 1, reference numeral 5 is arranged in the meter to detect the own vehicle speed and control a signal Sa corresponding to the detected speed.
A vehicle speed sensor that outputs to PU3, a stop lamp switch 6 that detects the turning on of a stop lamp, detects an ON of a foot brake, and outputs an ON detection signal Sb to the control CPU 3, and 7 is a light emission for alarm as one of alarm means. A diode (hereinafter, a light emitting diode is referred to as an LED) 8 is an alarm speaker as another alarm means. When the inter-vehicle distance approaches the alarm level, the alarm LED 7 is turned on and an alarm buzzer sounds from the speaker 8. Is issued.

In FIG. 1, reference numeral 10 denotes a volume for adjusting the volume of an alarm buzzer sound, 11 denotes a display for displaying the distance between vehicles, time between vehicles, and other characters, and 12 denotes a timing setting switch comprising a slide switch. The operation mode of the automatic mode with the reference set value as the reference value and the manual mode with the alarm level variably set from the reference set value is provided for selection. Function as a variable means for setting the variable amount of.

That is, in the timing setting switch 12, the center position of the operation knob is a selection position of the automatic mode,
When this position is selected, the alarm level becomes the reference set value.If the operation knob is shifted to the left or right from this center position, the mode switches from the automatic mode to the manual mode, and if it is shifted to the left, the alarm timing The alarm level is lower than the reference set value so that it is later than in the automatic mode, and if it is shifted to the right, the alarm level is higher than the reference set value so that the alarm timing is earlier than in the automatic mode. The alarm level changes from the reference set value to the minus or plus direction in accordance with the amount of shift of the operation knob of the timing setting switch 12 from the center position to the left or right.

Further, in FIG. 1, reference numeral 14 denotes a learning switch as operating means for setting a change mode for changing a reference set value of an alarm level when the automatic mode is selected, and 15 denotes a learning switch which is turned on. The learning LED 16 is lit to indicate that learning is in progress, and the learning end LED 16 is for learning the reference set value in the change mode.
Lights to indicate that the correction has been completed.

At this time, when the learning switch 14 is turned on, the control CPU 3 detects from the ON detection signal Sb of the stop lamp switch 6 that the foot brake is turned on, and for example, turns on the foot brake three times in 10 minutes. Then, the reference set value of the alarm level is corrected based on the inter-vehicle distance by the scan laser radar 2 when the foot brake is turned on.

Each of the switches 1, 12, 14, the scan laser radar 2, the control CPU 3, the LEDs 7, 15,
16, the speaker 8, the volume 10, and the display unit 11 are unitized, and each unit is supplied with power such as an illumination illumination power source, an IG power source, and a constant power source from the outside, and also supplies a ground (ground). .

Incidentally, the control CPU 3 also has a function of detecting an abnormality of the vehicle speed sensor 5, and a detailed configuration for that is shown in FIG.

In FIG. 2, reference numeral 3a denotes an input unit to which the signal Sa from the vehicle speed sensor 5 and the ON detection signal Sb from the stop lamp switch 6 are input, 3b a judgment unit, 3c a display control unit, and 3d a timer. The determination unit 3b determines that the state in which the signal Sa from the vehicle speed sensor 5 is not input, the relative speed V with respect to the preceding vehicle is equal to or higher than the predetermined speed Vth (for example, 20 km / h), and the stop lamp switch 6 is off. 3
A predetermined t time counted by d (for example, t = 3
Second) to determine whether or not to continue, to determine that the vehicle speed sensor 5 is abnormal when continuing for time t, output an abnormal display command signal to the display control unit 3c, and to the display unit 11 under the control of the display control unit 3c. The fact that there is an abnormality is displayed on the vehicle speed sensor 5, and at this time, the display unit 11 functions as a notification unit. Here, the state where there is no output from the vehicle speed sensor 5 refers to a state where the sensor output remains at the high level or the low level even though the vehicle is traveling.

Next, the operation of detecting an abnormality of the vehicle speed sensor 5 will be described with reference to the flowchart of FIG.

As shown in FIG. 3, it is determined whether or not the signal Sa from the vehicle speed sensor 5 has been input to the input unit 3a (step S1). If the determination result is NO, the determination is YES. Is repeated until it passes, and the determination result is YE
If S, it is determined whether or not the relative speed V of the preceding vehicle with respect to the own vehicle is equal to or higher than the predetermined speed Vth, for example, 20 km / h (Step S2). If the determination result is NO, the process returns to Step S1. If the determination result is YES, it is determined whether or not the stop lamp switch 6 is in the off state, that is, whether or not the on detection signal Sb is input to the input unit 3a from the stop lamp switch 6 (step S3).

If the decision result in the step S3 is NO, that is, if the foot brake is depressed and the stop detection signal Sb is inputted from the stop lamp switch 6, the process returns to the step S1, and the decision result in the step S3 Is YE
If S, the timer 3d starts counting (step S4), and the timer 3d counts up to determine whether or not a predetermined t time of 3 seconds has elapsed (step S5). If not, step S
The determination of 5 is repeated.

On the other hand, if the decision result in the step S5 is YES, there is no signal Sa from the vehicle speed sensor 5, and the relative speed V
Is more than 20km / h and stop lamp switch 6
A determination is made as to whether or not the OFF state continues (step S6). If this state is not continuing and the determination result is NO, the process returns to step S1, and if the determination result is YES. Since it is determined that an abnormality such as a disconnection or a short circuit has occurred in the vehicle speed sensor 5, a display notifying the abnormality of the vehicle speed sensor 5 is displayed on the display unit 11 under the control of the display control unit 3d (step S7). finish.

When the abnormality of the vehicle speed sensor 5 is notified in this way, for example, the driver can know that the vehicle speed sensor 5 is disconnected or short-circuited, and the inter-vehicle distance warning system is not operating normally. Can be determined.

Further, the display on the display unit 11 allows the driver to quickly respond to abnormalities, for example, by repairing the vehicle speed sensor 5 as appropriate.

Therefore, according to the above-described embodiment, the abnormality in the vehicle speed sensor can be accurately detected by the inter-vehicle distance warning system itself without using another system such as a navigation system.

In the above embodiment, a case has been described in which it is determined whether or not the stop lamp switch 6 is off (in a state where the foot brake is not depressed) in order to determine the abnormality of the vehicle speed sensor 5. It is not always necessary to determine whether the stop lamp switch 6 is turned off. At least, there is no signal Sa from the vehicle speed sensor 5 and the relative speed V is equal to or higher than the predetermined speed Vth. Judge it.

Further, in the above-described embodiment, the case where the abnormality of the vehicle speed sensor 5 is notified by the display unit 11 has been described, but it is a matter of course that the buzzer or the lamp may be used to notify the abnormality other than the display unit 11. .

[0030]

As described above, according to the first aspect of the present invention, when there is no output signal of the vehicle speed sensor and the relative speed with respect to the preceding vehicle is higher than the predetermined speed for a predetermined period of time, Since it is determined that the vehicle speed sensor is abnormal, the inter-vehicle distance warning system itself can be detected without using another system such as a navigation system as in the past, and the abnormality of the vehicle speed sensor can be accurately detected with a simple configuration. Can be detected.

According to the second aspect of the invention, when it is determined that the vehicle speed sensor is abnormal, the abnormality is notified by the notifying means, so that the driver or the like can easily know the abnormality of the vehicle speed sensor. It becomes possible, and it is possible to respond quickly to abnormalities.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a partial block diagram of the same.

FIG. 3 is a flowchart for explaining the operation of the above.

[Explanation of symbols]

 2 Scan laser radar (measurement means) 3 Control CPU (command means) 3b Judgment unit 3d Timer 5 Vehicle speed sensor 11 Display unit (notification means)

Claims (2)

(57) [Claims] 1. A vehicle speed sensor for detecting a vehicle speed of a host vehicle, a measuring device for measuring an inter-vehicle distance between the host vehicle and a preceding vehicle running ahead, and an output signal of the vehicle speed sensor and a value measured by the measuring device for the front vehicle. Command means for judging whether or not the inter-vehicle distance to the vehicle has approached the alarm level at the current vehicle speed and outputting an alarm command signal when approaching; and alarm means for operating in response to the alarm command signal to issue an alarm An inter-vehicle distance warning system comprising: determining whether or not a state in which the output speed of the vehicle speed sensor is absent and the relative speed of the preceding vehicle to the own vehicle is equal to or higher than a predetermined speed continues for a predetermined time, and continues for a predetermined time. A method for detecting an abnormality of the vehicle speed sensor in the inter-vehicle distance warning system. 2. The method for detecting an abnormality of a vehicle speed sensor in an inter-vehicle distance warning system according to claim 1, wherein when it is determined that the vehicle speed sensor is abnormal, the abnormality is reported by a reporting unit.