JPH0313551B2 - - Google Patents

Description

Detailed Description of the Invention "Industrial Application Field" The present invention is designed to detect obstacles around the vehicle by receiving ultrasonic waves emitted from an ultrasonic unit mounted on a vehicle and reflected by obstacles. The present invention relates to an obstacle detection device for a vehicle.

"Prior Art" As a conventional vehicle obstacle detection device, for example, a device disclosed in Japanese Patent Application Laid-Open No. 57-84377 is known. This system uses ultrasonic waves to detect the location and presence of obstacles around the vehicle.

In the obstacle detection device described above, an ultrasonic unit consisting of a pair of an ultrasonic transmitter and an ultrasonic receiver is installed, for example, in the rear of a vehicle, and the ultrasonic transmitter emits ultrasonic waves at regular emission intervals. A sound wave is emitted in a certain direction, and the reflected wave of the above-mentioned ultrasonic wave input to an ultrasonic receiver is detected at a certain sampling period. It detects the reflection time of ultrasonic waves until they return, and detects the position and direction of obstacles.

Therefore, when a suitable obstacle exists, the waveform received by the ultrasonic receiver as described above is as shown in FIG. 5a. As shown in the figure, in general, when an ultrasonic wave is emitted, an ultrasonic wave A due to wraparound is received by the ultrasonic receiver, and after a reflection time corresponding to the distance from the ultrasonic transmitter to the obstacle, the ultrasonic wave A is detected due to the presence of the obstacle. Obstacle waveform B is detected.

``Problems with the prior art'' With the conventional obstacle detection device, the sharp obstacle waveform B shown in Figure 5a is obtained when the obstacle is a stationary object such as a wall, a car, or a person. For example, in the case of an object whose shape changes from time to time, such as a woman's skirt or a rotating billboard, and the direction of the ultrasonic reflection surface changes, Figure 5a shows A sharp obstacle waveform B as shown in FIG. 5B cannot be obtained, but a collapsed waveform is obtained as shown by B' in FIG. 5B. Therefore, such a waveform is often smaller than the judgment reference level C, and its existence cannot be determined in many cases. Therefore, it is naturally possible to detect the obstacle waveform B' as described above by lowering the judgment reference level C, but in this case, noise will also be picked up. This results in a decrease in detection accuracy.

``Object of the Invention'' Therefore, the object of the present invention is to provide a method that can be applied to unstable objects where the direction of the reflective surface of the object changes from time to time without lowering the judgment standard level. An object of the present invention is to provide a vehicle obstacle detection device capable of detecting the presence of obstacles.

``Structure of the Invention'' In order to achieve the above object, the main means adopted by the present invention is to receive ultrasonic signals emitted from an ultrasonic unit mounted on a vehicle and reflected by obstacles. In a vehicle obstacle detection device that detects the position of obstacles around the vehicle, the received ultrasonic waveform is divided into predetermined periods, and the differential value of the ultrasonic waveform is calculated for each divided period. This is an obstacle detection device for a vehicle in which the sign is determined, a rank value corresponding to the sign is assigned to each cycle, and the rank value is repeatedly integrated a plurality of times.

Among the above configuration requirements, the differential may be calculated strictly using a differentiating circuit, but as shown in the example below, it can be calculated instead by simply detecting the difference between adjacent data at each fixed period. Good too.

“Example” Next, the first example embodying the present invention will be described.
The present invention will be better understood by explaining it with reference to FIGS.

Here, FIG. 1 is a flowchart showing a data analysis procedure in an obstacle detection device for a vehicle according to an embodiment of the present invention, and FIGS. 2a, b, and c show examples of changes in unstable obstacle waveforms. Graph, Figure 3a,
b, c are graphs showing the ramp values corresponding to the signs of the differential values for each sampling period of each waveform, corresponding to Fig. 2 a, b, c, respectively; Fig. 4 is a graph showing Fig. 3 a,
It is a graph showing the state where the differential values shown in b and c are integrated. Note that the following example is only one specific example of the present invention, and is not intended to limit the technical scope of the present invention.

First, a data processing procedure of an obstacle detection device according to an embodiment of the present invention will be explained according to the flowchart shown in FIG. Note that S1, S2,
S3... indicates the number of the processing procedure (step).

As shown in FIG. 1, when an ultrasonic wave is first emitted from an ultrasonic transmitter, a counter starts at S1. This counter is used to generate a sampling period for periodically sampling the reflected sound taken in from the ultrasonic receiver, and S2
When the count is counted up, the received wave signal from the ultrasonic receiver is sampled (S3). At the same time, the counter starts again (S4) and the sampled value obtained in S3 is stored in the A register (S5). In this way, when the output signal of the ultrasonic receiver in the first sampling period is stored in the A register, the process waits in S6 until the value of the counter started in S4 reaches a predetermined value. When the count is up in S6, the input signal of the ultrasonic receiver is sampled again in S7, and the counter is restarted in S8. The sampling value in S7 is stored in the B register in S9, and the sampling value in S10 is stored in the B register in S9.
Compare the contents of the register with the contents of the B register.

In S10, if the content of the B register, that is, the value of the data sampled later, is larger than the content of the A register, that is, the data sampled earlier, that is, if the change in data is an increasing function, the control is performed in S11. Add +1 to the data memory corresponding to the cycle number.
Furthermore, in S10, if the content of the A register is greater than or equal to the content of the B register (in the case of a decreasing function), the content of the data memory corresponding to the sampling period number is set to 0, as shown in S12. Add (not change). When the processing in S11 or S12 is completed, the value of the B register is transferred to the A register, and in S13, and in the following S14, it is determined whether the sampling number n has reached the maximum value n _MAX or not. If so, the process returns to S6 and the processes from S6 to S13 are repeated. Furthermore, when n reaches n _MAX , the next ultrasonic wave is emitted as indicated by S0, and the processes from S1 to S14 are repeated. By repeating such ultrasonic emission an appropriate number of times, +1 or 0 is accumulated in the data memory corresponding to each sampling period number, and a peak appears in the part where the number of times that becomes an increasing function is large.

For example, what is shown in Figure 2a is an example of an unstable obstacle waveform in which the reflection state changes from moment to moment, and the data obtained from the reflection of the ultrasonic wave emitted in the Nth emission period. , the sampling period is expressed as Δt. Moreover, what is shown in Fig. 2b is an obstacle from the same obstacle obtained by the emission of the N+1th ultrasonic wave, which is delayed by one emission period from the emission of the ultrasonic wave shown in Fig. 2a above. This is a physical waveform, and as shown in the figure, it shows that the waveform changes with time. Above figure 2a
The processing in the flowchart of FIG. 1 regarding the waveform shown in FIG. 1 will be explained. Since the processing in S1 to S5 is only for the first sampling, the processing will be skipped and explained from S6. first
Let us proceed by assuming that the sample value of P _o has already been stored in the A register. In S6,
When counting up, the P _o+1st sample value is taken in and stored in the B register.
9. In S10, the value of P _o and the value of P _o+1 are compared, and if P _o+1 is larger, the process goes to S11;
If P _o =P _o+1 or P _o is larger than P _o+1 , the process advances to S12. In S11, +1 is added to the nth data memory, and then the process proceeds to S13.

On the other hand, in S12, the process proceeds to S13 without changing the value of the n-th data memory.
In S13, the sampling value of P _o+1 is transferred to the A register. In the case shown in Figure 2 a, P _o+1 > P _o , so the data memory corresponding to this is
1 is added. A similar process is performed between P _o+1 and P _o+2 , and in this case +1 is added to the data shown in FIG. 2a. Thus, in the data shown in FIG. 2a, 1 is also added to the n, n+1, n+2, and n+6th data memories, and no change occurs in the other data memories. Figure 3a is
This shows the state of change in the data memory. In this way, data is formed by one ultrasonic wave emission up to the data memory corresponding to the n-th sample period number, and when this is completed, the next ultrasonic wave is emitted.

The formation of data due to the second ultrasound generation is shown in FIG. 2b, and the corresponding change in the data memory contents is shown in FIG. 3b. Similarly, the formation of data in response to the third ultrasound generation is the second
FIG. 3c shows a corresponding change in the data memory contents. In the flowchart shown in FIG. 1 above, in S11 and S12, if the data is an increasing function, 1 is added to the contents of the corresponding data memory, so the steps shown in FIG. 3 a, b, c are performed. The sum of the changes in the data memory is stored as the final data memory value, and the content of the integrated data memory is the nth data memory value, as shown in Figure 4. It is understood that the more the value becomes the maximum and the more such integration is repeated, the more the content of the n-th data memory reaches its peak and grows.

This means that as long as there is an obstacle, even if the reflected wave from it is small like the disturbance waveform B' shown in Figure 5b, the reflected wave will be at the very end where the obstacle exists. Since it always shows a state of increasing somewhat from zero, that is, an increasing function, the integral value at this position always becomes a peak value, and a very clear maximum value is formed here, just like when the obstacle is a fixed wall. This is because it can be done.

On the other hand, in areas other than the edge of the obstacle, the data repeatedly becomes an increasing function and a decreasing function, so even if these are integrated, the data hardly grows, so the peak value is No. Further, since the timing of occurrence of noise is not periodic, even if the noise is integrated, it does not form a peak concentrated in one place, and the influence of noise is completely ignored.

In the above embodiment, the sign of the differential value of the reflected wave is determined, a rank value of +1 or 0 is assigned to each cycle according to the sign, and the thus assigned rank value is integrated for the number of times the ultrasonic wave is generated. By doing so, the data at the edge of the obstacle is peaked. Therefore,
By expressing the nature of the data using rank values of +1 or 0 as described above, it is possible to
It has become possible to greatly simplify the data structure and reduce memory.

``Effects of the Invention'' As described above, the present invention detects the position of obstacles around the vehicle by receiving ultrasonic signals emitted from an ultrasonic unit mounted on the vehicle and reflected by obstacles. In the object detection device, the received ultrasonic waveform is divided into predetermined periods, and the differential value of the ultrasonic waveform is calculated for each divided period to determine its sign, and a rank value is determined according to the sign. This vehicle obstacle detection device is characterized by assigning the rank value to each cycle and integrating the rank value repeatedly several times, so it targets obstacles whose reflecting surface shape changes from time to time. Even in this case, the position of the edge of the obstacle is analyzed so that it can be seen, and the reliability of obstacle determination is improved at once.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing a data analysis procedure in a vehicle obstacle detection device according to an embodiment of the present invention; FIGS. 2a, b, and c are graphs showing examples of changes in unstable obstacle waveforms; FIG. Figures 3a, b, and c are graphs showing the rank values corresponding to the signs of the differential values for each sampling period of each waveform corresponding to Figures 2a, b, and c, respectively, and Figure 4 is graphs that correspond to Figure 3a. , b, c, a graph showing the integrated state of the differential values shown, fifth
Figures a and b are graphs showing the structure of reflected waves obtained using conventional vehicle obstacle detection devices, respectively. Explanation of symbols, A... wraparound waveform, B... obstacle waveform, P _o , P _o+1 , P _o+2 ... data.

Claims (1)

[Claims] 1. In a vehicle obstacle detection device that detects the position of obstacles around the vehicle by receiving ultrasonic signals emitted from an ultrasonic unit mounted on the vehicle and reflected by obstacles, dividing the ultrasonic waveform into predetermined periods, calculating the differential value of the ultrasonic waveform for each divided period, determining its sign, and assigning a rank value to each period according to the sign; An obstacle detection device for a vehicle, characterized in that the rank value is repeatedly integrated a plurality of times. 2. The vehicle obstacle detection device according to claim 1, wherein the rank value is +1 if it has a positive sign, and 0 if it has a negative sign or 0.