JP2006047140A - Method and detector for detecting axial shift in radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect an axial shift of a radar system in a vehicle single body. <P>SOLUTION: A micro reflecting material is arranged in one part of a vehicular body located in front of an attaching position of the radar system 100 for a vehicle, and located along a direction different from that of the radar system 100, the radar system 100 is attached to the body 101 to conform a directional direction of an antenna with the detection direction, a reference data about the micro reflecting material is acquired using the radar system 100 attached by this manner, a using time data about the micro reflecting material is acquired by the radar system 100, in a using time, and the using time data is compared with the reference data to determine the presence of the axial shift of the radar system 100 when a comparison result therein exceeds a preset fixed value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for detecting an axis deviation of a radar apparatus and an axis deviation detecting apparatus, and more particularly, to an axis of a radar apparatus capable of easily detecting an axis deviation by a single vehicle when the vehicle is used in a radar apparatus attached to a vehicle. The present invention relates to a deviation detection method and a detection apparatus.

  In recent years, various traveling control systems have been developed and have already been put into practical use in order to ensure safety when driving a car. For example, an inter-vehicle distance control system (ACC system, adaptive cruise control system) is a system that controls the inter-vehicle distance in the front-rear direction to be properly maintained and has already been put into practical use. In addition, a Stop & Go system (traffic jam tracking system), an inter-vehicle warning system, and the like have been developed and are in a practical stage. In order to realize such a travel control system, it is necessary to attach a radar device (laser radar, millimeter wave radar, etc.) to the vehicle and detect and correctly recognize objects before and after the vehicle.

  When such a radar apparatus is attached to a vehicle, there is a problem in that the measurement accuracy of the radar is lowered if the attachment position and angle are deviated from a predetermined state set in advance. In extreme cases, a situation may occur in which the safety device does not operate because only the road surface is detected and the preceding vehicle is not detected, or the oncoming vehicle in the adjacent lane is erroneously detected as the preceding vehicle and the safety device malfunctions.

  Since the radar apparatus is usually installed in a bumper or a emblem of a vehicle, the attached state cannot be visually observed from the outside. Therefore, when the radar device is attached to a vehicle, the radar device is operated in a specific environment determined in advance, and the reception level and reception direction from the reference reflector are compared with specified values (true value ± tolerance). Whether or not the attachment is accurate is detected, and the attachment position and the attachment direction are adjusted so as to be accurate. Under a specific environment, it means a wide space where there are no buildings in the surrounding area or where the entire area is covered with a radio wave absorption band.

  Such a conventional method and apparatus for detecting an axis deviation of a radar apparatus is described in, for example, Patent Document 1 or Patent Document 2 shown below.

  However, even if the installation (installation) environment is correctly adjusted as described above when the radar apparatus is attached to the vehicle, the axis deviation of the radar apparatus may occur with the use of the vehicle after shipment. Therefore, in order to always operate the radar apparatus correctly, it is desirable that the presence or absence of the axis deviation of the radar apparatus can be confirmed every time the user uses the vehicle. In order to confirm the axis deviation of the radar device by the conventional axis deviation detection method, as described above, there is no building around the area, or a wide space where the entire area is covered with a radio wave absorber is required. It is not realistic to demand such a special environment from the vehicle owner who is an end user. Even if such an environment is prepared, if it is necessary to go to such a place to check the misalignment of the radar device every time the vehicle is used, it is not a product.

JP2003-240837 JP2003-255041

  The present invention has been made to solve the above-described problems, and does not require a specific space for checking the misalignment of the radar device, and detects the misalignment of the vehicle alone when the vehicle is used. An object of the present invention is to provide a novel axis deviation detection method and axis deviation detection apparatus for a radar apparatus.

  In order to solve the above-described problems, a method for detecting an axis deviation of a radar apparatus according to the present invention includes a method for detecting a partial micro-reflecting material of a vehicle body in a direction different from a detection direction of the radar apparatus in front of a radar apparatus mounting position of a vehicle. Placing the radar device at the attachment position with the antenna directing direction coinciding with the detection direction, obtaining reference data regarding the micro-reflecting material using the attached radar device, and A step of obtaining in-use data relating to the micro-reflecting material by the radar device when the vehicle is in use, a step of comparing the reference data with the in-use data, and the comparison result having a predetermined constant value. If exceeding, it is determined that the radar apparatus is misaligned.

  Further, an axis deviation detection device for a radar apparatus according to the present invention includes a minute reflector disposed on a part of a vehicle body in a direction different from a detection direction of the radar apparatus in front of a radar apparatus attachment position of the vehicle, A radar device mounted at the mounting position with the antenna pointing direction aligned with the detection direction; a storage unit that stores data relating to the micro-reflecting material measured using the mounted radar device as reference data; and A comparison unit that compares in-use data relating to the micro-reflecting material measured by the radar device during use with reference data stored in the storage unit;

  The radar device is attached to a predetermined position of the vehicle body so that the directivity direction of the antenna matches a preset detection direction of the radar. In this case, a minute reflective material is arranged in a part of the vehicle body in a direction different from the detection direction, that is, in a direction different from the detection direction, that is, a direction shifted from the mounting axis of the radar device, to serve as a reference reflection point. . The radar apparatus is operated in a state where the radar apparatus is normally attached to the vehicle body, data relating to the reference reflection point is measured, and this is stored as reference data.

  At the time of use of the vehicle, for example, at the start of driving of the vehicle after the vehicle is handed over to the user or at an arbitrary time during driving, the radar apparatus measures data related to the reference reflection point and compares it with the reference data. If the difference between the operating data and the reference data is within a predetermined allowable range, it is determined that there is no or no negligible axis misalignment of the radar apparatus, and the operation of the radar apparatus is continued. On the other hand, if the difference exceeds a predetermined allowable range, it can be determined that a non-negligible shift has occurred in the mounting shaft of the radar apparatus. By doing so, the user can detect the axis deviation of the radar device by itself when the vehicle is used without requiring a specific space for detecting the axis deviation of the radar device.

  If the reference reflection point is arranged at a position corresponding to the main lobe and side lobe in the antenna directivity characteristic of the radar device, that is, the valley of the directivity, the data value of the reference reflection point even if the mounting shaft of the radar device is slightly shifted. Change will be greater. Therefore, it is possible to detect the axis deviation with high accuracy. Further, by providing a plurality of reference reflection points, it is possible to detect the axis deviation with higher accuracy and to know in which direction the axis deviation occurs.

  When an axis deviation is detected in the radar apparatus, if the operation of the radar apparatus is continued in such a state, it is very dangerous because the object is erroneously recognized or the distance to the object is erroneously measured. For this reason, it is possible to stop the operation of the radar apparatus immediately when an axis deviation is detected, and display the fact on the display of the navigation apparatus or warn the user by voice.

  Further, if the radar apparatus is provided with an antenna axis adjustment mechanism, the direction of the antenna axis can be adjusted so that the difference is substantially eliminated based on the comparison result between the reference data and the in-use data. .

  FIG. 1 is a diagram illustrating a state where the radar apparatus 100 is attached to the front bumper 102 of the vehicle 101. The radar apparatus 100 is usually mounted behind the front bumper 102, or is mounted in the hood or emblem of the vehicle.

  FIG. 2 is a diagram illustrating an overall configuration of a general millimeter wave radar apparatus 100. In the millimeter wave radar device 100, a transmission signal modulated in the millimeter wave RF unit 2 is formed based on a signal from the transmitter control circuit 3T built in the analog circuit 3, and this is converted into a millimeter wave. The light is radiated to the front of the vehicle via the flat transmitting / receiving antenna 1.

  The millimeter wave reflected by the object in front of the vehicle is received by the antenna 1 and supplied to a mixer (not shown) in the millimeter wave RF unit 2. Since a part of the transmission signal is input to the mixer, the output of the mixer is a beat signal including information such as the distance to the reflecting object and the relative movement speed. This output signal is sent to a DSP (digital signal processor) 4 through a receiving circuit 3R built in the analog circuit 3.

  The DSP 4 includes a fast Fourier transformer (FFT, not shown), and performs frequency analysis on the input beat signal to extract in which frequency band the peak signal is present. Information regarding the peak signal is sent to the microprocessor 5 as peak data. In the microprocessor 5, the distance to the reflecting object and the relative movement speed of the reflecting object are calculated from the input peak data.

  The microprocessor 5 is connected to the vehicle travel control ECU 6 and receives vehicle speed, curve information, and the like from the ECU 6 and uses them to calculate the position and speed of the reflector. The ECU 6 also receives information such as the distance from the microprocessor 5 to the reflecting object, the relative speed, and the like, and uses it for various types of vehicle travel control. For example, when it is detected that the distance from the preceding vehicle, which is a reflective object, is below a certain value, the ECU 6 sounds an alarm to warn the driver to ensure safety and automatically activates the brake. Then, control is performed to return the inter-vehicle distance to a certain value or more.

  In the radar apparatus of FIG. 2, a flat transmitting / receiving antenna is used as the antenna 1, but the present invention is not limited to this, and separate antennas may be provided for transmission and reception. . Further, if the antenna 1 is fixed so as to face only a certain front of the vehicle, the detection range (detection angle) of the preceding vehicle is narrowed. They may be swung left and right to emit a plurality of millimeter wave beams in front of the vehicle.

  FIG. 3 is a diagram showing the electric field directivity of the antenna 1. In the radar apparatus, a directional antenna is used as the antenna 1 and, therefore, main lobes and side lobes as shown in the figure are generated in radio wave transmission / reception characteristics. The directivity characteristics of the antenna are determined when the antenna is manufactured. The radar apparatus stores the directivity in an internal circuit in advance, and the position and size of the target object based on the reflected wave from the target object. In the case of identifying etc., the calculation is performed in consideration of this directivity.

  When the radar device 100 is attached to the vehicle body, the direction having the highest antenna directivity is attached so as to coincide with the detection direction of the radar device. If this direction is deviated, the measurement accuracy of the radar apparatus decreases. The adjustment of the antenna axis when the radar apparatus is attached to the vehicle body is performed by a method using a specific space as described in Patent Document 1 or 2, for example. However, even if the radar apparatus is correctly attached to the vehicle body in this way at the time of vehicle shipment, the mounting axis of the radar apparatus deviates from the initial state as the vehicle travels. A situation occurs that deviates from the detection direction.

  In the present invention, in order to detect that the mounting axis of the radar apparatus has deviated from the initial state, the metal is positioned in front of the mounting position of the radar apparatus and on an extension in a direction deviating from a predetermined detection direction of the radar apparatus. A reference reflecting point is created by arranging a minute reflecting material such as. If the mounting position of the radar apparatus is inside the bumper, a position having a reflection level different from the reflection level of the bumper body inside the bumper is selected as the reference reflection point. In one embodiment, this position is on the bumper on an extension in a direction corresponding to the vicinity of the boundary between the main lobe and the side lobe of the antenna directivity shown in FIG.

  At the time of shipment of the vehicle, with the radar apparatus 100 normally attached to the vehicle body 101, the radar apparatus 100 measures the reception level and reception direction of the reflected signal from the reference reflection point, and uses the data as a reference value, for example, micro Stored in the processor 5. The vehicle is shipped in this state.

  After shipment, as long as the radar device is not displaced from its initial state, the positional relationship between the radar device and this reference reflection point will not change, and the reception level and direction from the reference reflection point will vary depending on the external environment of the vehicle. It is always constant (reference value ± tolerance) without being affected by. Accordingly, the axis deviation of the radar apparatus can be detected by comparing the measurement data from the reference reflection point during operation of the radar apparatus with a reference value stored in advance. Note that the number of reference reflection points is not necessarily one, and a plurality of reference reflection points may be provided. In addition, by providing the reference reflection point near the boundary between the main lobe and side lobe of antenna directivity, the reception level changes greatly with a slight axis shift. Axis deviation can be detected with high accuracy.

  FIG. 4 is a flowchart showing a processing procedure for executing the axis deviation detection method of the radar apparatus according to the embodiment of the present invention. Note that the flowchart shown in FIG. 4 is normally programmed in advance in the microprocessor 5 in the signal processing unit 1 in the radar apparatus 100 shown in FIG. 2, and is automatically activated by the activation of the radar apparatus to start processing.

  When the radar apparatus is activated in step S1, first, the measurement data of the reference reflection point is fetched (step S2). As an example, the measurement data of the reference reflection point is data relating to the reception level and direction. Next, reference data (reception level and direction related to the reference reflection point) written in advance at the time of shipment of the vehicle in the microprocessor 5 of the radar apparatus body or a memory (not shown) externally attached to the radar apparatus body. Data) is read (step S3).

  As already explained, the reference reflection point is located in a part of the vehicle body in front of the mounting position of the radar device and deviated from the direction showing the highest antenna directivity when the radar device is normally mounted. The point that is located is selected. For example, when the radar apparatus is mounted inside the front bumper of the vehicle, the reference reflection point is a part of the bumper that is shifted to the left or right from the front of the radar apparatus mounting position. By providing the reference reflection point in front of the radar device mounting position of the vehicle in this way, the positional relationship between the normal mounting position of the radar device and the reference reflection point (distance and azimuth (angle) is fixed, and the reception level is also determined by the radar. It is not affected by the surrounding environment (dirt, weather, etc.) when the apparatus is activated, and therefore these values can be stored in the memory as standard values.

  In yet another embodiment, the reference reflection point is arranged so as to exist in the vicinity of the boundary between the main lobe and the side lobe in the antenna directivity characteristic diagram when the radar apparatus is normally attached to the vehicle. In this case, since the reception level changes greatly with respect to a slight shift of the mounting axis of the radar apparatus (shift in the horizontal axis direction in FIG. 3), it is possible to detect the axis shift with high accuracy.

  In step S4, the reference reflection point measurement data captured from the radar apparatus is compared with the reference data. In step S5, it is determined whether or not the comparison result is equal to or less than a preset allowable value. If the comparison result is less than or equal to the allowable value, it is determined that there is no axis deviation of the radar apparatus or that it is within a negligible range without greatly affecting the measurement accuracy, and normal measurement operation of the radar apparatus is started ( Step S6), the axis deviation detection flow is terminated.

  If it is determined in step S5 that the comparison result exceeds a preset allowable value, the operation of the radar apparatus is stopped (step S7), because the axis deviation of the radar apparatus is so large that it cannot be ignored. Is notified to the driver (step S8). When an axis misalignment occurs, an error occurs in the distance to the preceding vehicle, and as a result, the brake assist is delayed, or the oncoming vehicle in the adjacent lane is detected to drive the brake assist. May occur.

  Therefore, when an axis deviation occurs, the operation of the radar apparatus is immediately stopped, and various traveling control systems depending on the radar apparatus are stopped. Notification of the radar device automatic stop to the driver is performed by displaying a warning lamp on the instrument panel of the vehicle or displaying it on the display of the navigation device.

  FIG. 5 is a flowchart showing a processing procedure of the axis deviation detection method according to the second embodiment of the present invention. In the present embodiment, three reference reflection points having different distances and directions from the radar apparatus are provided, and standard values and allowable values set in advance for each reference reflection point and measured values (data) at each reference reflection point. And a reference value) to detect whether or not an axis deviation has occurred at each reference reflection point.

  That is, the radar apparatus is activated in step S10, the counter value is set to 1 (step S11), and the measurement data of the reference reflection point 1 is captured (step S12). Furthermore, in step S12, the reference data of the reference reflection point 1 is retrieved from a memory (not shown) (step S13), and is compared with the acquired measurement data to detect the difference (step S14). If the detected difference is within the preset allowable value (YES in step S15), the process proceeds to step S16, T is incremented by 1, and after confirming that T is 3 or less in step S17, the step is again performed. S12 and subsequent steps are executed for the next reference reflection point 2.

  If the difference between the measured value and the stored standard value exceeds the allowable value at any reference reflection point in the process of reference reflection point 1 to reference reflection point 3 (No in step S15), the process proceeds to step S18. The operation of the radar apparatus is stopped immediately after the shift, and the driver is notified in step S19 that the radar apparatus has been automatically stopped.

  If T exceeds 3 in step S17 (YES in step S17), that is, if the comparison result in step S15 is within an allowable value for all of the reference reflection points 1 to 3, the routine proceeds to step S20 and the radar apparatus is normal. The measurement operation is started, and the axis misalignment detection flow is completed.

  As described above, various embodiments have been described and described. According to the method and apparatus for detecting an axis deviation of a radar apparatus according to the present invention, a vehicle alone can be used without requiring a specific space for axis deviation detection. Axis deviation can be detected. Therefore, when the vehicle is used, the user can easily detect the axis deviation of the radar device, and the reliability of the radar device and the reliability of various traveling control systems using measurement by the radar device can be improved. Further, by detecting the axis deviation and promptly notifying the driver of this, it is possible to shorten the time required to repair the radar device mounting environment. Furthermore, by providing a shaft misalignment correction mechanism in the installation environment of the radar apparatus, it becomes possible to correct the shaft misalignment from the detection result.

The figure which shows the state which attached the radar apparatus to the vehicle body. The figure which shows the whole structure of a millimeter wave radar apparatus. The figure which shows antenna directivity. The figure which shows the operation | movement flow of the axis deviation detection method concerning one Embodiment of this invention. The figure which shows the operation | movement flow of the axis deviation detection method concerning other embodiment of this invention.

Explanation of symbols

1 Antenna 2 RF unit 3 Analog circuit 3R Receiver circuit 3T Transmitter control circuit 4 DSP
5 Macro processor

Claims (6)

Disposing a micro-reflecting material on a part of the vehicle body in a direction different from the detection direction of the radar device in front of the radar device mounting position of the vehicle;
Attaching the radar device to the attachment position by matching the antenna directivity direction to the detection direction;
Obtaining reference data regarding the micro-reflecting material using the attached radar device;
Obtaining in-use data relating to the micro-reflecting material by the radar device during use of the vehicle;
Comparing the reference data with the in-use data;
A method of detecting an axis deviation of a radar apparatus, comprising: determining that the radar apparatus has an axis deviation when the comparison result exceeds a preset constant value.   2. The method according to claim 1, wherein the step of disposing the micro-reflecting material in front of the position where the radar device is attached includes the step of arranging the micro-reflecting material near a boundary between a main lobe and a side lobe of the antenna directivity of the radar device. A method for detecting an axis deviation of a radar apparatus, comprising:   3. The method according to claim 1, wherein the step of disposing the minute reflecting material in front of the radar device mounting position includes disposing the minute reflecting material in a plurality of directions different from the detection direction. The step of comparing compares the reference time data acquired for the plurality of micro-reflecting materials arranged in the plurality of directions with the use time data, and detects the axis deviation of the radar apparatus. A minute reflector disposed on a part of the vehicle body in front of the radar device mounting position of the vehicle and in a direction different from the detection direction of the radar device;
A radar device mounted at the mounting position with the antenna pointing direction matched with the detection direction;
A storage unit for storing, as reference data, data related to the microreflecting material measured using the attached radar device;
An axis misalignment detection apparatus for a radar apparatus, comprising: a comparison unit that compares in-use data relating to the micro-reflecting material measured by the radar apparatus during use of the vehicle with reference data stored in the storage means.   5. The apparatus according to claim 4, wherein the minute reflecting material is disposed in the vicinity of a boundary between a main lobe and a side lobe in the directivity characteristic of the antenna.   The apparatus according to claim 4 or 5, wherein the minute reflecting material is arranged in a plurality of directions different from the detection direction, respectively.

Images