JPH0132473B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an automotive rear monitoring device that uses ultrasonic waves to monitor the rear of a vehicle when it is reversing, particularly for obstacles that are detected only temporarily when reversing. It concerns collision avoidance.

BACKGROUND TECHNOLOGY A rear monitoring device for a vehicle detects and notifies rear obstacles when the vehicle is reversing.
It is used to ensure safety.

Here, a rear view monitoring device for a vehicle that has been generally used in the past has an ultrasonic transducer installed at the rear of the vehicle diagonally downward to the rear, as shown in, for example, Japanese Unexamined Patent Publication No. 74675/1983. Then, by intermittently supplying an ultrasonic generation drive signal from the oscillation circuit to the ultrasonic transmitter, pulsed ultrasonic waves are radiated to the rear road surface.

On the other hand, an ultrasonic receiver receives pulsed ultrasonic waves reflected from a road surface or the like and converts them into a received signal. Then, the time difference between this received signal and the ultrasonic generation drive signal is determined, and if this time difference becomes shorter than a predetermined value, it is assumed that a protrusion exists in the rear, and the backward movement is An alarm is being generated. In addition, if the above time difference becomes longer than a predetermined time range, or if reflected waves are no longer received, it is assumed that there is a recess such as a groove or quay, and a warning for backward movement is issued. is configured to do so.

However, in the automobile rear monitoring device having the above-mentioned configuration, the monitoring range X becomes triangular in shape as it widens toward the rear, as shown in FIG. In other words, the monitoring range X has a triangular shape determined by the relationship between the angle α of ultrasonic emission and reception of the ultrasonic transducer 1 and the maximum monitoring distance M. In this case, since the monitoring range X is triangular, the monitoring width becomes narrower as the distance from the ultrasonic transducer 1 toward the rear increases.

As a result, for example, the utility pole 2 located on the side of the monitoring range X as shown in FIG. 1 moves out of the monitoring range X as shown by the dotted line 2' as the automobile moves backward. Therefore, there is a problem in that the monitoring of the utility pole 2 when backing up becomes temporary, making it impossible to avoid a collision.

DISCLOSURE OF THE INVENTION Accordingly, an object of the present invention is to provide a rear monitoring device for a motor vehicle that prevents collisions due to temporary detection of obstacles caused by a triangular monitoring range.

In order to achieve such an objective, the rear monitoring device for a vehicle according to the present invention detects the distance between the vehicle and the obstacle at the time of detecting the obstacle, and detects the distance immediately before the vehicle's backward distance reaches this memorized distance. The system avoids a collision by issuing a brake control signal.

In a vehicle rear monitoring device with such a configuration, by being located at a position shifted to the left and right from directly behind the vehicle, as the vehicle moves backward and approaches, it moves out of the triangular monitoring range and temporarily For obstacles that would otherwise be detected, the relative distance at the time the obstacle was detected is stored, and the vehicle's retreating distance is sequentially subtracted from this stored distance, and the result of this subtraction is determined in advance. When the specified margin distance is reached, a brake control signal is generated to stop the vehicle from moving backward.

Therefore, even for an obstacle that is only temporarily detected, it is possible to reliably avoid a collision with the obstacle when the vehicle is reversing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a circuit diagram showing an embodiment of an automobile rear monitoring device according to the present invention. In the same figure,
Reference numerals 3 and 4 are an ultrasonic transmitter and an ultrasonic receiver fixed to the rear part of the automobile toward the rear, and 5 is an ultrasonic distance measurement circuit that uses ultrasonic waves that are intermittently generated inside the vehicle. The sound wave generation drive signal A is supplied to the ultrasonic transmitter 3, and the reflected wave reception signal B of the ultrasonic receiver 4 is input, and the distance to the obstacle at the shortest position is measured based on the time difference between the two. Signal C
Output. 6 is a monitoring distance setting device for setting the monitoring distance M, and 7 is a comparison circuit, in which the distance signal C generated from the ultrasonic distance measuring circuit 5 is determined from the monitoring distance setting signal D output from the monitoring distance setting device 6. When the alarm signal E is small, an alarm is generated by generating an alarm signal E and supplying it to a buzzer 8 as a sounding element. 9 is a flip-flop circuit, and 10 is an AND gate which sets the flip-flop circuit 9 by determining the coincidence between the alarm signal E and the reset output signal generated from the flip-flop circuit 9. 1
Reference numeral 1 denotes a preset counter which presets the distance signal C using the set output signal of the flip-flop circuit 9 and also receives a distance pulse F supplied from a sensor (not shown) that detects the rotation of the wheel.
count down sequentially. Reference numeral 12 denotes a margin distance setting device for setting the margin distance for obstacles when the vehicle is stopped; and 13, a matching circuit in which the output signal G of the preset counter 11 matches the output signal H of the margin distance setting device 12. In this case, a brake control signal I is output to stop the backward movement of the vehicle. And these flip-flop circuits 9,
The AND gate 10, the preset counter 11, the margin distance setter 12, and the coincidence detection circuit 13 store the distance signal output from the ultrasonic distance measuring circuit when the alarm signal is generated, and also store the distance signal output from the ultrasonic distance measurement circuit when the alarm signal is generated. A control means is configured to sequentially subtract a vehicle backward distance from the stored distance signal, and generate a brake control signal to stop the vehicle from moving backward when the subtraction result reaches a predetermined margin distance to an obstacle. This means that

In the automobile rear monitoring device configured as described above, when a power switch (not shown) is turned on,
An ultrasonic generation output signal A is intermittently generated from an oscillation circuit provided inside the ultrasonic distance measuring circuit 5 and supplied to the ultrasonic generator 3. When the ultrasonic transmitter 3 receives the ultrasonic generation output signal A, it emits ultrasonic waves toward the rear of the automobile. When this emitted ultrasonic wave is irradiated to an obstacle located on the side within the monitoring range X, for example, a utility pole 14, this reflected wave is received by the ultrasonic receiver 4,
A reflected reception signal B is output. Then, the ultrasonic distance measuring circuit 5 measures the distance to the obstacle from the time difference between the ultrasonic generation drive signal A and the reflected wave reception signal B, and outputs the distance signal C.

On the other hand, when the distance signal C is less than the monitoring distance signal D supplied from the monitoring distance setting device 6, the comparison circuit 7 determines that an obstacle exists in the monitoring range X and sends out an alarm signal E. The buzzer 8 is activated to generate an alarm. in this case,
The utility pole 14 serving as an obstacle is located on the side within the monitoring range, and even if the vehicle backs up only slightly, the utility pole will be out of the monitoring range as shown by a dotted line 14'. Therefore, the detection of the utility pole 14 is temporary, and the buzzer 8 only issues a momentary warning.

On the other hand, when the alarm signal E is generated, the output signal of the AND gate 10 becomes "H", the flip-flop circuit 9 is set, and its reset output signal "L" is supplied to the AND gate 10. Prevents reception of subsequent alarm signals E. Further, when the flip-flop circuit 9 is set, the preset counter 11 is set by the rising edge of the set output signal, so that the distance signal C is preset.

Next, when a distance pulse F corresponding to the backward movement of the automobile is supplied, the preset counter 11 sequentially counts down the distance pulse F and outputs the counted value as an output signal G. When the output signal G of the preset counter 11 matches the output signal H output from the margin distance setting device 12, a brake control signal I is generated from the coincidence detection circuit 13 to immediately stop the backward movement of the vehicle. A brake system (not shown) is actuated by this brake control signal I, thereby stopping the backward movement of the automobile.

In this case, the brake operation is automatically started at a position that is a margin distance preset by the margin distance setting device 12 from the utility pole 14 as an obstacle, and the brake operation is automatically performed to immediately stop the backward motion of the vehicle. It will be done. Therefore, since the monitoring range has a triangular shape, it is possible to reliably avoid a collision due to the vehicle moving backwards even with an obstacle that is detected only temporarily.

It goes without saying that it is necessary to reset the flip-flop circuit 9 if the vehicle is to be moved backwards again.

As explained above, the rear monitoring device for an automobile according to the present invention is located at a position shifted left and right from directly behind the automobile, and as it approaches the automobile,
For obstacles that are temporarily detected due to being out of the monitoring range, the relative distance at the time the obstacle was detected is memorized, and the vehicle's retreating distance is sequentially subtracted from this memorized distance. , when this subtraction result reaches a predetermined margin distance,
Since the brake control signal is generated to stop the backward movement of the automobile, it has an excellent effect of reliably avoiding collisions with obstacles when the automobile is backing up.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the operation of detecting a rear obstacle in a conventional automobile rear monitoring device, and FIG. 2 is a circuit diagram showing an embodiment of the automobile rear monitoring device according to the present invention. 3 is an ultrasonic transmitter, 4 is an ultrasonic receiver, 5 is an ultrasonic distance measuring circuit, 6 is a monitoring distance setting device, 7 is a comparison circuit, 8 is a buzzer, 9 is a flip-flop circuit, 10 is an AND gate, 11 is a preset counter, 12 is a margin distance setter, and 13 is a coincidence detection circuit.

Claims (1)

[Scope of Claims] 1. An ultrasonic transmitter and an ultrasonic receiver fixed to the rear of an automobile toward the rear, an ultrasonic generation drive signal supplied to the ultrasonic transmitter, and the ultrasonic wave. an ultrasonic distance measuring circuit that measures the distance to an obstacle based on the time difference between the reflected wave received signal supplied from the receiver and outputs a distance signal; A rear monitoring device for a vehicle includes a comparison circuit that generates an alarm signal and drives a sounding body to generate an alarm when the vehicle is within a predetermined monitoring distance range,
A distance signal outputted from the ultrasonic distance measuring circuit when the alarm signal is generated is stored, and the vehicle reversing distance from the time when the alarm signal is generated is sequentially subtracted from the stored distance signal, and the result of the subtraction is the distance to the obstacle. A rearward monitoring device for a motor vehicle, comprising a control means for generating a brake control signal to stop the backward movement of the motor vehicle when the vehicle reaches a predetermined margin distance. 2. The control means for generating the brake control signal for stopping the backward movement of the automobile sets the flip-flop circuit to match the reset output outputted from the flip-flop circuit and the alarm signal, which is initially reset. an AND gate, a preset counter that presets a distance signal when the set output of the flip-flop circuit is generated, and subtracts a value according to the vehicle's backward distance signal; and a margin distance setting device that sets the margin distance from the vehicle to the obstacle. and,
Claims characterized by comprising a coincidence detection circuit that generates a brake control signal when detecting coincidence between the margin distance value output from the margin distance setting device and the output value of the preset counter. The automobile rear monitoring device according to item 1.