JP2011220860A - Obstacle detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an obstacle detection device that can detect a direction of presence of an obstacle at a low cost.SOLUTION: The obstacle detection device mounted to a vehicle to detect an obstacle around the vehicle, including distance detection means that irradiates a detection wave around the vehicle and detects the distance to the obstacle based on a reflection wave reflected by the obstacle present at the periphery of the vehicle, and direction calculation means that calculates a direction of presence of the obstacle based on a difference value between a first distance and a second distance, the first distance being a distance to the obstacle acquired by the distance detection means at time t1, and the second distance being a distance to the obstacle acquired by the distance detection means at time t2 after a predetermined time is elapsed from the time t1.

Description

  The present invention relates to an obstacle detection device, and more particularly to an obstacle detection device mounted on a vehicle.

  Conventionally, an obstacle detection device that detects obstacles around a vehicle has been developed. Such an obstacle detection device is used, for example, as a part of a parking support system that detects a parking space, supports parking operation guidance, and the like by detecting another vehicle present in the parking lot as an obstacle. Yes.

  An example of the obstacle detection apparatus as described above is disclosed in Patent Document 1. The vehicle surrounding monitoring system disclosed in Patent Literature 1 transmits a pulse wave, and receives echo reflected waves formed by reflecting the pulse wave on an obstacle by a plurality of sensors arranged at different positions of the vehicle. And the said vehicle periphery monitoring system calculates the presence direction of the said obstacle based on the reception time difference of the echo received by each sensor.

JP 2004-317360 A

  However, in the conventional obstacle detection device as disclosed in Patent Document 1, a vehicle has a plurality of sensors (antenna elements) that receive reflected waves from the obstacle in order to detect the direction in which the obstacle exists. Since it was necessary to mount, there existed a problem that high cost was needed in order to construct | assemble the said apparatus (system). Further, since a plurality of sensors and antenna elements are mounted on the vehicle, there are problems such as an increase in size of the device and an increase in the total weight of the vehicle on which the device is mounted.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an obstacle detection apparatus that can detect the presence direction of an obstacle at low cost.

  In order to solve the above problems, the present application adopts the following configuration. That is, the first invention is an obstacle detection device that is mounted on a vehicle and detects obstacles around the vehicle, irradiates a detection wave around the vehicle, and detects obstacles around the vehicle. The distance detection means for detecting the distance to the obstacle based on the reflected wave reflected and the distance to the obstacle acquired from the distance detection means at the time t1 are defined as a first distance, and a predetermined time has elapsed from the time t1. Direction calculation for calculating the presence direction of the obstacle based on the difference value between the first distance and the second distance, with the distance to the obstacle acquired from the distance detection means at time t2 as the second distance And an obstacle detection device.

  According to a second invention, in the first invention, the vehicle further includes a movement distance calculating means for calculating a moving distance of the vehicle between the time t1 and the time t2, and the direction calculating means includes the first distance and the second distance. The direction in which the obstacle exists is calculated based on the difference value and the movement distance.

  According to a third aspect, in the first aspect, the vehicle further includes movement determination means for determining whether or not the vehicle has moved a predetermined movement distance, and the second distance detection means is configured to detect the vehicle in advance from time t1. A time point when the vehicle has moved by a predetermined moving distance is set as time t2, a second distance from the vehicle to the obstacle at the time point is detected, and the direction calculation means calculates the difference value between the first distance and the second distance, the moving distance, Based on the above, the direction of the obstacle is calculated.

According to a fourth aspect of the present invention, in any one of the second to third aspects, when the direction calculation means sets the difference value between the first distance and the second distance to ΔL and the movement distance to d, the following formula (a) Based on this, the direction θ of the obstacle is calculated.
θ = sin ⁻¹ (ΔL / d) (a)

  According to a fifth invention, in any one of the first to fourth inventions, the distance detecting means is a pulse-type single beam radar device.

  According to the first invention, as the distance detecting means, for example, a single radar device capable of detecting only distance information to the obstacle can be used to calculate the direction in which the obstacle exists. Therefore, it is not necessary to use an expensive radar device equipped with an array antenna or the like in order to detect the direction in which the obstacle exists. Further, it is not necessary to mount a plurality of radar devices on the vehicle. That is, according to the first aspect, the direction of the obstacle can be detected at a low cost. In addition, according to the first invention, the same function as that of the conventional apparatus can be obtained with less hardware than the conventional apparatus, so that the apparatus can be reduced in size and weight.

  According to the second invention, it is possible to calculate the direction in which an obstacle exists with relatively few parameters. Further, the position of the obstacle can be detected every time a predetermined time elapses.

  According to the third aspect, it is possible to calculate the direction in which the obstacle exists with relatively few parameters. Further, the position of the obstacle can be detected every time the vehicle moves a predetermined moving distance.

  According to the fourth aspect of the present invention, it is possible to calculate the direction in which an obstacle exists with a simple calculation process, that is, with a relatively small amount of processing.

  According to the fifth aspect of the present invention, the obstacle detection device according to the present invention can be configured using a radar device having a low-cost and simple configuration. In addition, by using a pulse type radar device, it is possible to detect the distance to the obstacle with relatively high accuracy compared to the case of using a frequency modulation type radar device. The direction in which the obstacle exists can be calculated with high accuracy.

An example of a block diagram showing the configuration of the obstacle detection apparatus 1 An example of a flowchart showing details of processing executed by the ECU 20 The figure which shows a mode that the obstruction detection apparatus 1 detects an obstruction. Enlarged view of the vicinity of the antenna element 11 shown in FIG.

  Hereinafter, the obstacle detection apparatus 1 according to the embodiment of the present invention will be described. The obstacle detection device 1 is a device that is mounted on the host vehicle 100 and detects obstacles around the host vehicle 100. First, the configuration of the obstacle detection apparatus 1 will be described with reference to FIG. FIG. 1 is an example of a block diagram illustrating a configuration of the obstacle detection apparatus 1. As shown in FIG. 1, the obstacle detection device 1 includes a radar device 10 and an ECU 20. The host vehicle 100 also includes a vehicle speed sensor 30 and a parking assistance device 40. The vehicle speed sensor 30 and the parking assist device 40 are each electrically connected to the ECU 20.

  The radar device 10 is a device that detects the distance to obstacles around the host vehicle 100. The radar apparatus 10 includes at least one antenna element 11 that transmits and receives a detection wave signal such as an electromagnetic wave or an ultrasonic wave. The radar apparatus 10 detects the distance from the host vehicle 100 to the obstacle based on the reflected wave information of the detection wave signal irradiated around the host vehicle 100. Hereinafter, the distance to the obstacle detected by the radar device 10 at this time is referred to as a detection distance L (n). Note that the subscript n of the detection distance L (n) represents the current time, and n-1, n-2,... Represent the time one sampling time ago, two sampling times ago,. That is, L (n) indicates the distance to the obstacle at the present time, and L (n-1) indicates the detection distance detected at the time point one sampling before. The radar apparatus 10 is electrically connected to the ECU 20 and transmits data indicating the detection distance L (n) to the ECU 20. In addition, the radar apparatus 10 shall be mounted in the front side of the own vehicle 100, and shall detect the obstruction which exists in the side of the own vehicle 100, for example.

  The radar device 10 is typically a pulse-type single beam radar device. Furthermore, the radar device 10 is preferably a UWB (Ultra Wide Band) pulse radar device. The radar apparatus 10 preferably encodes (encodes) a detection wave signal to be transmitted and received. According to such an encoding process, for example, when the own vehicle 100 is equipped with a radar device other than the radar device 10, or a vehicle equipped with another radar device exists in the vicinity of the own vehicle 100. In some cases, it is possible to prevent interference between the detection wave signal transmitted / received by the radar device 10 and the detection wave signal transmitted / received by another radar device. A specific example of the radar device 10 is an example, and any type of radar device may be used as the radar device 10 as long as the device has the above-described function. For example, the radar apparatus 10 may be a radar apparatus that detects an obstacle by transmitting and receiving an electromagnetic signal or an optical signal such as a laser.

  The ECU 20 is typically a control device including an information processing device such as a CPU (Central Processing Unit), a storage device such as a memory, an interface circuit, and the like. The ECU 20 calculates the presence direction of the obstacle based on information acquired from the radar device 10 and the vehicle speed sensor 30. Hereinafter, the obstacle presence direction calculated by the ECU 20 is referred to as a detection direction θ (n). Note that the subscript n in the detection direction θ (n) represents the current time as in the detection distance L (n) described above. The ECU 20 outputs data indicating the detection distance L (n) and the detection direction θ (n) to the parking assistance device 40.

  The vehicle speed sensor 30 is a sensor device that detects the traveling speed V of the host vehicle 100. The vehicle speed sensor 30 transmits data indicating the detected traveling speed V to the ECU 20. The vehicle speed sensor 30 may detect the traveling speed V using any conventionally known method.

  The parking assistance device 40 is a device that assists the parking operation of the driver of the host vehicle 100. For example, the parking assist device 40 maps the position of the obstacle based on the detection distance L (n) and the detection direction θ (n) received from the ECU 20. And if the parking assistance apparatus 40 detects the area | region which can park the own vehicle 100, the said position will be notified to a driver by an image display, an audio | voice, etc. FIG. The parking assist device 40 also predicts the risk of collision between the host vehicle 100 and an obstacle, and issues a warning when the risk of the collision is high, or automatically activates the brake of the host vehicle 100. To do. According to the obstacle detection device 1 according to the present invention, it is possible to detect not only the detection distance L (n) but also the detection direction θ (n). It is possible to accurately grasp the positional relationship of the driver and appropriately assist the driver's parking operation.

  Next, a process executed by the ECU 20 will be described with reference to FIG. FIG. 2 is an example of a flowchart showing details of processing executed by the ECU 20. For example, when the IG power supply of the host vehicle 100 is set to the on state, the ECU 20 starts the process of the flowchart of FIG. When the process of the flowchart of FIG. 2 is started, the ECU 20 first executes a process of step S1.

  In step S1, the ECU 20 acquires the detection distance L (n) to the obstacle at the current time. Specifically, the ECU 20 acquires data indicating the detection distance L (n) from the radar device 10, and stores the current time and the data in association with each other in the storage device. In addition, although mentioned later for details, ECU20 performs the process of this step S1, whenever the sampling time (tau) passes, and acquires detection distance L (n). When the ECU 20 completes the process of step S1, the process proceeds to step S2.

In step S <b> 2, the ECU 20 calculates the travel distance d of the host vehicle 100. Specifically, the ECU 20 from the time (hereinafter referred to as time T (n-1)) when the previous detection distance L (n-1) is acquired to the current time (hereinafter referred to as time T (n)). The movement distance d during which the host vehicle 100 has moved is calculated. For example, the ECU 20 acquires the travel speed V from the vehicle speed sensor 30 and calculates the travel distance d based on the following equation (1).
d = V × τ (1)
The method for calculating the movement distance d is an example, and the ECU 20 may calculate the movement distance d using any conventionally known method. For example, when the travel speed V changes with time, the ECU 20 may calculate the travel distance d by integrating the travel speed V over time. Further, when the host vehicle 100 is equipped with a sensor such as an encoder that detects the movement distance d, the ECU 20 may acquire the movement distance d based on the output value of the sensor. When the process of step S2 is completed, the ECU 20 advances the process to step S3.

In step S3, the ECU 20 calculates the detected object direction θ based on the previous detection distance L (n−1) and the current detection distance L (n). Specifically, the ECU 20 first calculates the previous detection distance L (n−1) and the difference value ΔL between the detection distances L (n) stored in the storage device based on the following equation (2).
ΔL = L (n−1) −L (n) (2)

Next, the ECU 20 calculates the detection direction θ (n) based on the difference value ΔL. Hereinafter, a specific example will be described in which the host vehicle 100 detects the other vehicle 200 as an obstacle as illustrated in FIGS. 3 and 4. FIG. 3 is a diagram illustrating how the obstacle detection apparatus 1 detects an obstacle. FIG. 4 is an enlarged view of the vicinity of the antenna element 11 shown in FIG. As shown in FIG. 3, the ECU 20 detects the detection distance L (n-1) at the current time T (n) after detecting the detection distance L (n-1) at the past time T (n-1). At this time, since the host vehicle 100 has moved by the moving distance d between the past time T (n−1) and the current time T (n), the antenna element 11 that transmits and receives the detection wave signal as shown in FIG. Is also moved by the moving distance d. Here, since the moving distance d is sufficiently smaller than the detection distance L (n−1) and the detection distance L (n), the detection wave signal transmitted and received when detecting the detection distance L (n−1). And the propagation path of the detection wave signal transmitted and received when detecting the detection distance L (n) can be regarded as being substantially parallel to each other. Therefore, assuming that the detection direction θ (n−1) and the detection direction θ (n) have substantially the same value, the detection direction θ (n) is expressed by the following formula ( 3).
sinθ (n−1) ≈sinθ (n) = ΔL / d (3)
When the above equation (3) is transformed, it can be expressed as the following equation (4). Therefore, the ECU 20 calculates the detection direction θ (n) based on the difference value ΔL, the movement distance d, and the following equation (4).
θ = sin ⁻¹ (ΔL / d) (4)
The detection direction θ (n) is represented by an angle formed on a horizontal plane formed by an axis connecting the obstacle and the host vehicle 100 and an axis indicating the left-right direction of the host vehicle 100. After calculating the detection direction θ (n), the ECU 20 transmits data indicating the detection direction θ (n) and the detection distance L (n) to the parking assistance device 40. When the ECU 20 completes the process of step S3, the process proceeds to step S4.

  According to the process of step S3, the ECU 20 determines the direction in which the obstacle exists in the same manner as in the radar apparatus having a plurality of antenna elements based on the distances to the obstacle detected at different points at different times. Can be calculated. At this time, the ECU 20 can calculate the detection direction θ (n) by a simple process without performing a complicated process like a synthetic aperture radar. More specifically, in a general synthetic aperture radar using phase and frequency information, the antenna interval needs to be equal to or less than the wavelength of the detection wave signal irradiated by the radar device. On the other hand, since the ECU 20 according to the present invention calculates the detection direction θ (n) using the detection distance L (n) to the obstacle, the ECU 20 detects the movement distance d without being restricted by the wavelength of the detection wave signal or the like. The direction θ (n) can be calculated.

  In step S4, the ECU 20 determines whether the sampling time τ has elapsed. Specifically, the ECU 20 measures an elapsed time Δt from the time when the process of step S3 is completed. Then, the ECU 20 determines whether or not the elapsed time Δt is equal to or longer than the sampling time τ. When the elapsed time Δt becomes equal to or longer than the sampling time τ, the ECU 20 determines that the sampling time τ has elapsed and advances the process to step S5. On the other hand, if the elapsed time Δt is less than the sampling time τ, the ECU 20 determines that the sampling time τ has not yet elapsed, repeats the process of step S4, and waits until the sampling time τ elapses.

  In step S5, ECU20 determines whether the IG power supply of the own vehicle 100 was set to the OFF state. ECU20 completes the process of the flowchart of FIG. 2, when the IG power supply of the own vehicle 100 is set to the OFF state. On the other hand, when the IG power supply of host vehicle 100 is maintained in the on state, ECU 20 returns the process to step S1 and repeatedly executes the processes of the above steps.

  According to the processing of the ECU 20, the detection distance L (n) is obtained and the detection direction θ (n) is calculated every time the sampling time τ elapses.

  As described above, according to the obstacle detection apparatus 1 according to the present invention, it is possible to detect the direction in which an obstacle exists at low cost. Specifically, the obstacle detection device 1 according to the present invention can be configured by a single radar device 10 that can detect only distance information to an obstacle. Therefore, it is not necessary to use an expensive radar device equipped with an array antenna or the like in order to detect the direction in which the obstacle exists. Further, it is not necessary to mount a plurality of radar devices on the host vehicle 100. Therefore, it is possible to detect the position of the obstacle at a low cost. In addition, since the same function as that of the conventional device can be realized with a small amount of hardware, an effect of reducing the weight of the host vehicle 100 as compared with the conventional device can be obtained.

  In the above embodiment, an example in which the ECU 20 acquires the detection distance L (n) and calculates the detection direction θ (n) every time the sampling time τ elapses has been described. The detection distance L (n) may be acquired and the detection direction θ (n) may be calculated every time the movement is performed by the predetermined distance interval dth. When performing such processing, for example, in step S4, the ECU 20 calculates the moving distance d based on the elapsed time Δt and the travel speed V from the time when the processing of step S3 is completed, and the moving distance d is the distance interval. Wait until dth or higher. And ECU20 performs the process of the above-mentioned step S1 and step S3 when the movement distance d becomes more than the distance space | interval dth.

  Moreover, although the said embodiment demonstrated the example in which the obstacle detection apparatus 1 was mounted in a vehicle, you may apply so that the obstacle detection apparatus 1 may be mounted in other arbitrary mobile bodies. For example, the obstacle detection apparatus 1 may be mounted on a moving body such as an aircraft, a ship, construction equipment, and transport equipment.

  In the above embodiment, the obstacle detection device 1 is mounted on a vehicle that moves in the horizontal direction and the example of detecting the position of the obstacle in the horizontal direction has been described. However, the obstacle detection device 1 according to the present invention is It may be mounted on a moving body that moves in the vertical direction and applied so as to detect the vertical position of the obstacle.

  In the above-described embodiment, the case where a radar apparatus capable of detecting only the distance to the obstacle is used as the radar apparatus 10 is described as an example. However, the distance to the obstacle and the presence direction in the vertical direction of the obstacle can be detected. A simple radar device may be used as the radar device 10. When the obstacle detection device according to the present invention is configured by such a radar device, the obstacle existence direction can be detected in each of the vertical direction and the horizontal direction. It is possible to detect.

  The obstacle detection apparatus according to the present invention is useful as an obstacle detection apparatus capable of detecting the direction of the obstacle at low cost.

DESCRIPTION OF SYMBOLS 1 Obstacle detection apparatus 10 Radar apparatus 11 Antenna element 20 ECU
30 vehicle speed sensor 40 parking assist device 100 own vehicle 200 other vehicle

Claims (6)

An obstacle detection device that is mounted on a vehicle and detects obstacles around the vehicle,
A distance detecting means for irradiating a detection wave around the vehicle and detecting a distance to the obstacle based on a reflected wave reflected from the obstacle existing around the vehicle; from the distance detecting means at time t1 The first distance is the distance to the obstacle acquired, and the second distance is the distance to the obstacle acquired from the distance detection means at time t2 after a predetermined time has elapsed from time t1. An obstacle detection device comprising: a direction calculation unit that calculates the presence direction of the obstacle based on a difference value between the distance and the second distance. A moving distance calculating means for calculating a moving distance of the vehicle between the time t1 and the time t2,
2. The obstacle according to claim 1, wherein the direction calculation unit calculates the presence direction of the obstacle based on a difference value between the first distance and the second distance and the movement distance. Detection device. Movement determining means for determining whether or not the vehicle has moved a predetermined movement distance;
The second distance detection means detects a second distance from the vehicle to the obstacle at the time point as a time point t2 when the vehicle has moved a predetermined movement distance from the time point t1;
The radar apparatus according to claim 1, wherein the direction calculation unit calculates the presence direction of the obstacle based on a difference value between the first distance and the second distance and the movement distance. . When the difference value between the first distance and the second distance is ΔL and the movement distance is d, the direction calculation means calculates the obstacle existence direction θ based on the following equation (a). The obstacle detection device according to any one of claims 2 to 3, wherein the obstacle detection device is characterized.
θ = sin ⁻¹ (ΔL / d) (a)   The obstacle detection device according to claim 1, wherein the distance detection unit is a pulse-type single beam radar device.   The obstacle detection apparatus according to claim 1, wherein the detection wave is a sound wave or an electromagnetic wave.

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