KR101509945B1 - Object detection method of vehicle, and method for controlling parking assist system using the same - Google Patents

Abstract

The present invention relates to an object detection method using an ultrasonic sensor. The main purpose of the present invention is to provide an object detection method capable of preventing a malfunction caused in a corresponding system by ultrasonic signals and various noise signals transmitted from the other vehicle to the sensor and capable of improving the reliability of the system and the marketability of a vehicle by effectively processing the ultrasonic signals and the noise signals. To accomplish the above purpose, provided is an object detection method for a vehicle. The provided object detection method transmits ultrasonic signals from an ultrasonic sensor twice at a predetermined time interval in order to avoid noise, and detects an object using received ultrasonic signals due to the transmitted ultrasonic signals respectively. The provided object detection method comprises: a step (a) of transmitting ultrasonic signals twice, and measuring a time interval between two valid ultrasonic signals with sizes larger than a predetermined threshold and storing the time interval in a first database (DB) after transmitting the ultrasonic signals respectively and receiving the valid ultrasonic signals; a step (b) of newly changing and resetting a time interval for the following transmission of two ultrasonic signals using data on the time interval stored in the first database; and a step (c) of transmitting two of the ultrasonic signals at the reset time interval in the case of the following transmission of two of the ultrasonic signals, and detecting the object using received ultrasonic signals due to the transmitted ultrasonic signals.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of detecting an object of a vehicle and a method of controlling the parking assist system using the same,

The present invention relates to an object detection method using an ultrasonic sensor, and more particularly, to an object detection method using an ultrasonic sensor, and more particularly, to a method and apparatus for preventing an erroneous operation of an associated system caused by ultrasonic signals and various noise signals of other vehicles, It's about how you can.

Recently, as electronic communication and sensor technologies have greatly developed, systems that perform various intelligent functions using various sensors are mounted on a vehicle. One of them is an ultrasonic sensor for measuring the distance to an obstacle to support parking And a parking assist system (PAS).

The parking assist system (PAS) detects an obstacle on the front and rear sides of the vehicle and warns the driver of the risk of collision, thereby providing the driver with parking convenience. The system detects an obstacle through a plurality of sensors installed at specific locations of the vehicle, And detects the dangerous situation, the alarm system such as a buzzer or a display is operated to warn the driver.

In such a parking assist system, the distance from the vehicle to an object that can be recognized as an obstacle is measured. In order to detect an obstacle, the distance is calculated by measuring the time that the ultrasound signal output from the sensor collides with an object and is reflected.

However, in measuring distances using ultrasound signals, noise inflow in the same frequency band makes object detection difficult, and this is one of the main factors that makes system operation impossible.

That is, as shown in FIG. 1, when an ultrasonic signal and a noise signal transmitted from an ultrasonic sensor (PAS sensor) and reflected by an object enter the same time zone, it is difficult to accurately recognize the reflection waveform of the object. have.

Particularly, when noises are introduced, false alarms are generated even when there is no object, thereby causing confusion to the driver or lowering the reliability of the product. It is therefore necessary to effectively process the introduced noise to prevent false alarms.

Referring to FIG. 1, an ultrasonic pulse signal (TX pulse) output from a sensor, an ultrasonic signal reflected from an object, and a noise signal flowing in the same time zone are displayed. When the reflected ultrasonic signal returns to a set threshold, It is determined that the obstacle signal is a larger effective value, but there is a problem that the noise signal is mistaken as an obstacle signal.

In addition, even when an ultrasonic signal (a signal generated from a sensor of another vehicle) of another vehicle is received, a false alarm may occur.

Car ultrasonic sensors have a certain driving frequency (for example, a band between 40 kHz and 60 kHz), and most vehicle ultrasonic sensors use frequencies in similar bands, so there is a high possibility of inter-vehicle signal interference.

In the case where a sensor having a frequency of a similar frequency is operated in two vehicles, if an ultrasonic signal of one vehicle is input to an ultrasonic sensor of another vehicle, the ultrasonic signal of another vehicle is received, And it is possible to make false alarms.

When an ultrasonic signal of another vehicle is inputted, even if a filter having a high performance is used, it can not be distinguished from an ultrasonic signal of another vehicle in hardware.

Generally, the noise introduced into the ultrasonic sensor has a random shape as shown in FIG. 1, and the ultrasonic signal flowing from the other vehicle is also the same.

Depending on how long the ultrasonic signal is generated in the other vehicle and how much intensity is generated, it will be recognized as a different noise. Depending on the angle between the vehicle and the vehicle, the ultrasonic signal Will be recognized as different signals.

FIG. 2 is a view showing that an ultrasonic signal of another vehicle can be mistaken as an object. In FIG. 2, ultrasonic signals TX_pulse1 and 2 for detecting an obstacle are outputted from the vehicle and ultrasonic signals of the other vehicle are received.

FIG. 2 shows a situation in which the ultrasonic signal output from the vehicle is not received because it is not returned, that is, a situation where there is no object to be actually alarmed and there is no reflected signal.

The ultrasonic signal of the other vehicle can also be recognized as the same as the ultrasonic signal reflected from the object (the ultrasonic signal reflected and outputted from the subject vehicle).

In the conventional parking assist system, as shown in FIG. 2, for avoiding noise, two ultrasonic measurements are repeated in short time intervals for each sensor, and at the same time after each ultrasonic signal (TX pulse 1, 2) If all of the signals detected at this point in time are valid signals, they are recognized as objects.

However, if the ultrasonic signal of the vehicle is input to the ultrasonic sensor at an appropriate time as shown in FIG. 2 after the ultrasonic signal of the vehicle is output even if the measurement is performed twice, the object may be mistaken as a normal object reflection signal, In particular, the probability of false alarms is higher when the object detection cycle is similar in the ultrasonic sensors of two vehicles.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above problems, and it is an object of the present invention to provide a parking assisting system (PAS) of a vehicle, which effectively processes ultrasonic signals and noise signals of other vehicles flowing into a sensor, And to provide a method for improving the reliability of the system and the commerciality of the vehicle.

According to an aspect of the present invention, there is provided an object detecting method of a vehicle which transmits an ultrasonic signal in an ultrasonic sensor twice at a predetermined time interval for noise avoidance and detects an object using each ultrasonic signal received therefrom (A) transmitting two ultrasonic signals and receiving two effective ultrasound signals greater than a preset threshold value after transmission of the respective ultrasonic signals, measuring a time interval between the received signals, Storing; (b) re-changing a time interval for transmission of two ultrasonic signals by using time interval data stored in the first database; And (c) transmitting ultrasonic signals at the reset time intervals during the transmission of the two ultrasonic signals and detecting an object using the ultrasonic signals received therefrom.

In order to avoid noise, the ultrasonic sensor transmits an ultrasonic signal twice at a predetermined time interval and detects an object using each ultrasonic signal received from the ultrasonic sensor. Then, the obstacle is sensed and an alarm system is operated The method comprising: (a) transmitting two ultrasonic signals and receiving two effective ultrasonic signals greater than a threshold value set after transmission of each ultrasonic signal, wherein the time interval between the two received signals And storing the measured data in a first database (DB); (b) re-changing a time interval for transmission of two ultrasonic signals by using time interval data stored in the first database; (c) transmitting ultrasound signals at the reset time intervals when two subsequent ultrasound signals are transmitted and sensing an object using ultrasound signals received therefrom; And (d) selectively activating an alarm system according to distance information with respect to the object.

Thus, according to the present invention, it is possible to prevent false alarms that may be caused by ultrasonic signals and noise signals of other vehicles flowing into the sensor, and to improve reliability and vehicle commerciality of the system.

1 is a view showing that a noise signal is introduced into a sensor of a parking assist system along with an ultrasonic signal.
2 is a view showing an ultrasonic signal of another vehicle mistaken as an object in a sensor of a parking assist system.
3 is a view for explaining an object detection method according to the present invention.
4 is a flowchart illustrating a process of adjusting a transmission period of an ultrasonic sensor in order to prevent a system malfunction due to an ultrasonic signal of another vehicle in the present invention.
FIG. 5 is a diagram for explaining a method for preventing object misrecognition and system false alarm by providing a noise measurement period in the present invention.
6 is a flowchart illustrating a system operation process according to whether or not a noise signal is detected in the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains.

The present invention relates to an object detecting method using an ultrasonic sensor, and it is an object of the present invention to provide an object detecting method capable of preventing a system malfunction caused by various noise signals flowing into a sensor.

In particular, it is an object of the present invention to provide a method for effectively processing ultrasound signals and other noise signals of other vehicles flowing into a sensor from a parking assist system (PAS) of a vehicle, thereby preventing false alarms caused thereby and improving system reliability and vehicle commerciality .

The best way to prevent obstacle blindness and false alarms caused by ultrasonic signals from other vehicles in the parking assist system is to output ultrasonic signals to detect objects (obstacles) and process the signals received by the sensors. , The ultrasonic signal of the other vehicle flowing into the sensor is separated and the object detection period of the sensor is adjusted by avoiding the ultrasonic wave generation period of the other vehicle (the ultrasonic wave output period of the other vehicle sensor).

However, it is impossible to distinguish the signal transmitted to the sensor from the ultrasonic signal of another vehicle, and thus it is impossible to completely avoid the ultrasonic generation cycle of another vehicle.

Accordingly, the present invention proposes an algorithm capable of minimizing false alarms caused by ultrasonic waves generated in other vehicles by analyzing and learning signals input to the sensors.

FIG. 3 is a view for explaining an object sensing method according to the present invention. FIG. 3 is a view for explaining an embodiment in which the ultrasonic transmission period (TX_Period) of the sensor is varied by analyzing signals inputted to the sensor for preventing malfunction.

4 is a flowchart illustrating a process of adjusting a transmission period (TX_Period) of an ultrasonic sensor in order to prevent a system malfunction due to an ultrasonic signal of another vehicle in the present invention.

As shown in FIG. 3, in the parking assist system, two ultrasonic measurements through the sensor, that is, the first and second measurements repeated in a short time interval, are both effective reflection signals (the signal values are larger than the threshold value ) Is received, the object is detected using the reflection signal and the distance to the object is measured.

In this case, the two signals received by the ultrasonic sensor should be the reflection signals of the own vehicle that are returned from the ultrasonic signals (two signals output in short time intervals) It may be an ultrasonic signal of another vehicle that has flowed into the sensor as shown in Fig.

Also, in the example of FIG. 3, if both valid signals are received during the two measurement procedures, T_Period (effective signal interval), which is the time interval between the two valid signals, can be measured.

Accordingly, in the present invention, a control unit for sensing an object based on a sensor signal controls a sensor output to transmit two ultrasonic signals (TX pulse 1, 2) in a current transmission period (TX_Period) during two measurement processes, Measure T_Period, the interval between two valid signals received during the two measurements.

Here, the effective signal interval T_Period means a time interval of two valid signals respectively sensed after the output of each of the ultrasonic signals (TX pulse1,2) in the process of performing two ultrasonic measurements in a short time interval for noise avoidance.

Also, the measured T_Period value is stored in the memory, and whenever a new T_Period value is measured, the T_Period value is stored in the memory and converted into a database (DB).

At this time, the maximum number of T_Period values to be stored is set in consideration of the memory capacity and the CPU processing speed of the control unit, and the newly measured T_Period value is stored in the most front side of the T_Period DB (first database) .

Also, each time a new T_Period value is stored, the previously stored T_Period values are moved by one place in the DB and stored (divided into new and old order based on the storage time), and if the measured T_Period value is the same If the value is in DB, delete the old value of the two values.

On the other hand, using the T_Period values stored in the DB, the controller then resets the TX_Period, which is the time interval between the ultrasonic signals TX_P pulse1 and TX_P pulse2, for the subsequent two measurements, (Changed) TX_Period is used as the transmission period.

At this time, the reset TX_Period value is also stored in the memory in the same manner as the T_Period value to be a database (DB), and the newly reset TX_Period value is stored in the TX_Period DB (second database) together with the previous reset value. Is set to one of the values stored in the TX_Period DB, the stored values of the TX_Period DB become the usable TX_Period values in the future.

Here, the time interval TX_Period of the ultrasonic transmission means a time interval between two timings for obtaining one result, that is, an ultrasonic signal TX pulse1 of the first measurement and a TX pulse2 of the second measurement.

In resetting the TX_Period, the controller resets the TX_Period value to a value other than the T_Period value stored in the T_Period DB. The controller compares the values stored in the TX_Period DB with the values stored in the T_Period DB, And selects a value not in T_Period DB and resets it to TX_Period value.

If all the TX_Peridod values in the TX_Period DB exist in the T_Period DB, the oldest value in the TX_Period DB is set to the TX_Period value.

Also, if there are multiple values in TX_Period DB that are not in T_Period DB, set the oldest value among those multiple values (the value in TX_Period DB) to TX_Period value.

By changing the TX_Period value adaptively, it is possible to avoid misinterpreting the ultrasonic signal of the other vehicle as the object reflection signal.

Of course, in the parking assist system, while the vehicle is parked, the above-described two-times measurement at the interval of the TX_Period is continuously repeated, and the change in the distance to the object is continuously detected. In each of the two measurements And performs a subsequent measurement (first and second measurements for noise avoidance) by applying the reset TX_Period when the TX_Period value is reset. Further, when the TX_Period value is reset, the changed TX_Period is newly applied .

As a result, if the two ultrasound valid signals received by the actual object are ultrasound signals reflected from the real object, the time from the output of the ultrasound signals (TX pulse1 / TX pulse2) Therefore, even if the TX_Period value is arbitrarily changed, the distance to the object will be measured equally in the following two measuring processes.

However, if the measured T_Period value is based on the ultrasonic signal of another vehicle, if the TX_Period value is adjusted, the distance calculated in the subsequent two measurement processes (and the time until reception after the ultrasonic transmission) It is possible to prevent the ultrasonic signal from being erroneously recognized as an effective object.

5 is a view for explaining a method for preventing object misrecognition and system false alarm by providing a noise measurement period in the present invention, and FIG. 6 is a flowchart illustrating a control procedure of a parking assist system according to whether or not a noise signal is detected in the present invention It is a flowchart.

As shown in FIG. 5, a noise measurement period is set for a predetermined time before each measurement, and it is confirmed whether or not a current noise is generated through the noise measurement period.

That is, from the point of time when the sensor outputs the ultrasonic pulse signals (TX pulse 1, 2) for detecting the object, the predetermined period of time before that is set as the noise measurement period.

In this noise measurement period, the sensor monitors the RX reception signal without generating any ultrasonic signal, and when the signal exceeding a predetermined threshold value is detected, it is judged as noise.

If the ultrasonic signal TX pulse1 and the ultrasonic signal TX pulse2 are to be transmitted at intervals of TX_Period, it is determined that the signal is a noise signal when the signal is input in the noise measurement period during each measurement.

Even though the sensor does not generate or output an ultrasonic signal, the fact that a signal is received by the sensor means that noise is being input to the sensor, and the received ultrasonic signals are more likely to be noise.

Ultrasonic signals of other vehicles can also be judged as noise when they are received and detected in the noise measurement period, and then the measured signals can be regarded as noise and can be ignored.

6, first, the control unit determines whether the signal received through the ultrasonic sensor in the sensor noise information checking process is a signal of a noise measurement period, and a signal that is greater than a threshold value And so on.

At this time, if the signal detected during the noise measurement period and the signal value is larger than the threshold value, it is determined that the noise signal is detected.

When the control unit determines that the noise signal is detected, the system enters the noise mode (noise mode ON), and while the noise mode ON state does not generate an alarm (alarm OFF) The measured result is ignored, and it is confirmed whether or not the noise signal is detected again for the set time from the time when the noise mode is turned on.

In FIG. 6, 'Noise detection time = 0' indicates that the noise detection time is zero when the noise mode is on. If the noise signal is detected again within the set time in the noise mode on state as described later, Indicates that the noise detection time at the detection time is cleared again to zero.

The T_Period is measured even in the noise mode on state, and the process of updating the memory data, resetting the TX_Period, and the like are continuously performed.

In addition, when the noise is not re-detected for a set time (for example, 1 second) from the immediately preceding noise signal detection point (when the noise mode is turned on) in the noise mode on state, the noise mode is canceled, And performs a normal function of generating an alarm when an object is sensed.

If the noise signal is detected again within the set time (for example, 1 second) in the noise mode on state, the time is again calculated from that point (clear the noise detection time 0), and then the noise mode is maintained for the set time do.

As described above, in the present invention, a method of measuring the time interval between two effective signals received by the ultrasonic sensor and varying the transmission period of the ultrasonic sensor using the measured time interval data, and a method of measuring the noise signal It is possible to prevent the malfunction of the related system which may be caused by the ultrasonic signal of the other vehicle and various noise signals, and to improve the reliability of the system and improve the commerciality .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. Forms are also included within the scope of the present invention.

Claims (15)

A method of detecting an object in a vehicle, the method comprising: transmitting an ultrasonic signal from the ultrasonic sensor twice at a predetermined time interval for noise avoidance and sensing an object using each ultrasonic signal received from the ultrasonic sensor;
(a) transmitting the two ultrasonic signals, and when receiving two effective ultrasonic signals larger than a threshold value set after transmission of each ultrasonic signal, measuring a time interval between the received signals and storing the measured time interval in the first database step;
(b) re-changing a time interval for transmission of two ultrasonic signals by using time interval data stored in the first database; And
(c) transmitting ultrasound signals at the reset time intervals when two subsequent ultrasound signals are transmitted and sensing an object using ultrasound signals received therefrom;
And detecting an object of the vehicle.
The method according to claim 1,
Wherein the ultrasonic sensor is an ultrasonic sensor for a parking assist system used for operation of a parking assist system (PAS).
The method according to claim 1,
Wherein a maximum number of storage times for storing the time interval value between the two measured signals is set in the first database and the stored order is stored in the order of the stored time each time a new measured value is stored in the first database, When the same value as the measured value to be stored is already stored in the first database, the old value of the two values is deleted.
The method according to claim 1,
The time interval reset in step (b) is stored in the second database, and the reset time interval value in step (a), (b), and (c) Wherein the first database is set to a value that is not present in the first database.
The method of claim 4,
The maximum number of stored times for storing the reset time interval value is set in the second database, and the stored time intervals are stored for each time a new time interval value is stored in the second database. And when the same value as the reset value is already stored in the second database, the old value of the two values is deleted.
The method of claim 4,
And if the time interval value stored in the second database is a value existing in the first database, the oldest value among the values stored in the second database is reset as a time interval value.
The method of claim 4,
Wherein a time interval value in which the oldest value among the plurality of values is reset is set as a time interval value when there is a plurality of values not stored in the first database among the values stored in the second database.
The method according to claim 1,
The ultrasonic signal is set to the noise measurement period for a predetermined period of time based on a time point at which each ultrasonic signal in the step (a) is transmitted, and the ultrasonic signal received at a valid value larger than the threshold value set in the noise measurement period And determining that the object is a signal.
In order to avoid noise, an ultrasonic sensor transmits an ultrasonic signal twice at a set time interval, and an object is detected using each ultrasonic signal received from the ultrasonic sensor. Then, a parking assist system The control method comprising:
(a) transmitting the two ultrasonic signals, and when receiving two effective ultrasonic signals larger than a threshold value set after transmission of each ultrasonic signal, measuring a time interval between the received signals and storing the measured time interval in the first database step;
(b) re-changing a time interval for transmission of two ultrasonic signals by using time interval data stored in the first database;
(c) transmitting ultrasound signals at the reset time intervals when two subsequent ultrasound signals are transmitted and sensing an object using ultrasound signals received therefrom; And
(d) selectively operating the alarm system according to distance information with the object;
The parking assist system comprising:
The method of claim 9,
Wherein a maximum number of storage times for storing the time interval value between the two measured signals is set in the first database and the stored order is stored in the order of the stored time each time a new measured value is stored in the first database, When the same value as the measured value to be stored is already stored in the first database, the old value of the two values is deleted.
The method of claim 9,
The time interval reset in step (b) is stored in the second database, and the reset time interval value in step (a), (b), and (c) And the value of the first database is set to a value that is not present in the first database.
The method of claim 11,
The maximum number of stored times for storing the reset time interval value is set in the second database, and the stored time intervals are stored for each time a new time interval value is stored in the second database. And the old value of the two values is deleted when the same value as the reset value is already stored in the second database.
The method of claim 9,
Wherein the ultrasonic signal is set to a noise measurement period for a predetermined period of time based on a time point at which each ultrasonic signal in the step (a) is transmitted, and for the ultrasonic signal received at a valid value larger than a threshold value set in the noise measurement period, And judges that the parking assist system is in a signal.
The method of claim 12,
Wherein a noise mode for ignoring the detection result by the ultrasonic signal is performed during the set time without activating the alarm system when the noise signal is detected.
15. The method of claim 14,
The noise mode is canceled so that the normal operation is performed when the noise signal is not re-sensed. On the other hand, when the noise signal is detected again, And the noise mode is maintained during the set time period calculated from the predetermined time.

Images