Patent Publication Number: US-2011050525-A1

Title: Radar device and antenna angle adjusting method

Description:
The disclosures of Japanese Patent Application No. 2009-194894 filed on Aug. 26, 2009 and Japanese Patent Application No. 2009-205525 filed on Sep. 7, 2009, including specifications, drawings and claims are incorporated herein by reference in its entirety. 
     BACKGROUND 
     The present invention relates to a technique of adjusting a beam axis (an antenna angle) of a radar device to be installed on a vehicle. 
     An in-vehicle radar device to be installed on a vehicle, such as an automobile, scans a space around the vehicle with a radar signal in order to detect targets, such as other vehicles, pedestrians and objects on a road, which are mainly located on the same horizontal plane as the vehicle on which the radar device is installed. In order to detect those targets with high precision, it is preferable to direct a beam axis of the radar signal toward the horizontal direction (hereinafter, referred to as a reference direction) to maximize a reception gain. Accordingly, when installing a radar device on a vehicle, an operation of making the beam axis direct toward the reference direction by adjusting the tilt angle of a housing, in which an antenna is housed, with respect to the gravity direction (hereinafter, simply referred to as a tilt angle), that is, beam axis adjustment is performed. JP-A-2000-056009 discloses such a beam axis adjustment. 
     In the beam axis adjustment, in consideration of the manufacture error of each radar device, the tilt angle of the housing, at which the beam axis is directed toward the reference direction, is first detected for every radar device before the radar device is installed on the vehicle. Then, when the radar device is installed on the vehicle, the posture of the housing is adjusted to have the tilt angle detected beforehand. In this case, a worker roughly positions the housing of the radar device on the vehicle placed on the horizontal plane, fixes the housing to the vehicle, and then finely adjusts the tilt angle of the housing by a manual operation while viewing a level tube attached to the housing. 
     A radar device is generally installed at a low and inconspicuous position of the vehicle, such as an inner side of a bumper or a front grille, in order to suppress the influence on the design of the vehicle. Thus, the worker has to bend his or her body to perform the beam axis adjustment. In addition, since the installation space of the radar device is restricted, it is difficult to adequately ensure the operation space of the beam axis adjustment. For these reasons, the working efficiency in the beam axis adjustment tends to be low. Therefore, JP-A-2010-096588 (Japanese Patent Application No. 2008-266503 filed with Japan Patent Office on Oct. 15, 2008) proposes a radar device capable of improving the working efficiency in the beam axis adjustment. 
       FIG. 1A  is a perspective view illustrating a radar device disclosed in JP-A-2010-096588. 
     A radar device  10  has a planar antenna  14  and various electronic circuits which are housed in a rectangular housing  11 . A radome  11   a  is provided in a front portion of the housing  11 . In the following explanation, it is assumed that a side on which the radome  11   a  is provided in the housing  11  is a front side and the opposite side is a rear side. 
     The rear side of the housing  11  is fixed to an installation portion at a front part of the vehicle with a fixture  13  such as a bolt, in a state where the radome  11   a  is directed toward, for example, the front of the vehicle. In addition, the planar antenna  14  transmits a radar signal forward through the radome  11   a.    
       FIG. 1B  is a cross-sectional view illustrating the radar device  10  taken along a line A-A′ shown in  FIG. 1A . One end  14   a  of the planar antenna  14  is attached to the housing  11  through a tilting shaft  15  so that the other end  14   b  of the planar antenna  14  can tilt back and forth around the tilting shaft  15 . The planar antenna  14  is comprised of an array antenna, a patch antenna, or the like, and is provided in the housing  11  in a state where a surface on which an array or a patch is formed, directs toward the front. The planar antenna  14  forms a beam axis of a radar signal in a direction perpendicular to the surface. 
     An antenna angle detecting section  16  (for example, an acceleration sensor) which detects a tilt angle of the planar antenna  14  with respect to the gravity direction (hereinafter, referred to as an antenna angle) is provided on the back surface of the planar antenna  14 .  FIG. 1B  shows a state where the antenna angle is 0°. 
     In addition, an antenna moving section  18  which moves the planar antenna  14  to adjust the antenna angle is provided in the housing II. The antenna moving section  18  includes a sliding shaft  18   a  whose front end is rotatably engaged with the end  14   b  of the planar antenna  14  and which is slidable back and forth, a motor  18   b , and a deceleration mechanism  18   d  which decelerates the rotational motion of a shaft  18   c  of the motor  18   b  at a predetermined rate to convert the rotational motion of the shaft  18   c  into a sliding motion of the sliding shaft  18   a . The antenna moving section  18  makes the sliding shaft  18   a  slide forward/backward by performing positive rotation/negative rotation of the motor  18   c . If the sliding shaft  18   a  slides forward/backward, the end  14   b  of the planar antenna  14  moves forward/backward. As a result, the antenna angle of the planar antenna  14  is adjusted. 
     In this radar device  10 , the beam axis adjustment is performed as follows when installed on a vehicle. 
     The beam axis adjustment of the radar device  10  will be described with reference to  FIGS. 2A and 2B .  FIG. 2A  is a cross-sectional view illustrating the radar device  10  in a state where the housing  11  is installed on the vehicle. As shown in  FIG. 2A , it is assumed that the tilt angle of the housing  11  is α° (&gt;0°) when the housing  11  is attached to the vehicle placed on the horizontal plane. Hereinafter, for the sake of convenience, the tilt to the front side is expressed as a positive value and the tilt with respect to the rear side is expressed as a negative value. 
     Here, assuming that the initial antenna angle of the planar antenna  14  when the housing  11  is placed on the horizontal plane is 0°, the antenna angle when the housing  11  is installed on the vehicle is α°. 
     When a control signal which instructs the beam axis adjustment is input to a control unit (not shown) of the radar device  10 , the control unit starts driving the antenna moving section  18  in response to the control signal. A reference antenna angle (for example, 0°), which is an antenna angle at which the beam axis directs toward the reference direction, is set beforehand in the control unit, and the antenna moving section  18  moves the planar antenna  14  to adjust the tilt angle of the planar antenna  14  from α° which is detected by the antenna angle detecting section  16  to the reference antenna angle. In this way, the beam axis adjustment is performed without manually adjusting the tilt angle of the housing  11  by the worker. 
     According to the above-described radar device  10 , the beam axis can be adjusted when the radar device  10  is installed on the vehicle. In addition, the beam axis can be readjusted in the same manner described above at the time of vehicle checking and maintenance even if the tilt angle of the housing  11  changes due to vibration from the road surface during traveling or contact or collision with the other vehicle or an obstacle and thus the beam axis deviates from the reference direction (hereinafter, the beam axis adjustment when installing the radar device  10  on the vehicle is referred to as a first-time beam axis adjustment and the subsequent beam axis adjustment is referred to as a beam axis readjustment). In the radar device  10 , however, the following problems may occur at the time of the beam axis readjustment. 
       FIG. 2B  is a cross-sectional view illustrating the radar device  10  in a state where the tilt angle of the housing  11  changes after the first-time beam axis adjustment and the tilt angle of the housing  11  with respect to the gravity direction becomes β° (&gt;α°). In this situation, the antenna angle of the planar antenna  14  is β°. In order to perform the beam axis readjustment to set the antenna angle to a reference antenna angle, it is necessary to move the planar antenna  14  forward to change the antenna angle by β°. However, as shown in  FIG. 2B , if a distance between the planar antenna  14  and the inner wall of the radome  11   a  is short compared with β° by which the planar antenna  14  is to be tilted (hereinafter, referred to as a planned tilt angle), the end  14   b  of the planar antenna  14  comes in contact with the inner wall of the radome  11   a  before the planar antenna tilts forward by β° (arrow B 1 ). As a result, the sliding shaft  18   a  cannot slide forward any more. 
     As described above, if a change in the tilt angle of the housing  11  after the first-time beam axis adjustment increases, the sliding shaft  18   a  may become unslidable. In this case, in the deceleration mechanism  18   d  of the antenna moving section  18 , a worm gear attached to the motor shaft  18   c  may be abnormally engaged with a worm wheel to which the torque of the worm gear is transferred at the predetermined deceleration rate. Consequently, the deceleration mechanism  18   d  is fixed, the sliding shaft  18   a  cannot slide not only forward but also backward with the driving force of the motor  18   b  and then the antenna moving section  18  becomes unable to move the planar antenna  14 . As a result, the beam axis adjustment is not appropriately performed and thus the target detection accuracy may be reduced. Moreover, since it is necessary to overhaul the radar device  10  to dissolve the abnormal engagement, it result in a cost increase and an inconvenience. 
     The radar device installed on the vehicle transmits a transmission wave to a target and receives a reflection wave from the target to detect the target such as the other vehicle or an object placed on the road. To detect the target, it is necessary to adjust a direction of the beam axis of the radar device such that an intensity of the reflection wave becomes a predetermined value or more. Since the beam axis of the radar device is directed perpendicular to an antenna surface of the antenna, an antenna angle (an angle of the antenna) is adjusted to adjust the direction of the beam axis. 
     Here, since the installation of the radar device on the vehicle is performed in a limited space in the vehicle, which is different according to a type of the vehicle, it depends on the installation position of the radar device or the skill of a worker who perform the installation to realize a desired antenna angle at which the intensity of the reflection wave becomes equal to or larger than the predetermined value. 
     For this reason, the antenna angle for achieving a desired beam axis direction is calculated in advance, the calculated antenna angle is stored in a storage device of the radar device as a target angle, and an automatic adjustment to the target angle is performed using a tilt sensor and a motor. 
     JP-A-2004-156948 discloses that a light receiving lens and its lens holder are swingably held in an object detector for a movable body and the lens holder is fixed to perform an axis adjustment after a predetermined time elapses and the swing stops. 
     JP-A-10-132920 discloses monitoring a deviation amount of an attachment angle of a radar head to a vehicle from the reference value and notifying the driver that the deviation amount becomes a predetermined value or more. 
     However, in the case where the antenna angle adjustment is performed in a vehicle factory, a dealer, or the like, vibration caused by contact with a vehicle, such as opening and closing of a vehicle door or getting on and off the vehicle by a worker, at the time of the antenna angle adjustment after attaching the radar device to the vehicle, may be applied to the vehicle. As a result, since the output of the tilt sensor which detects the antenna angle is changed, the antenna angle may not be accurately adjusted. 
     The process disclosed in JP-A-2004-156948 is performed after simply waiting until the swing of the light receiving lens stops in the process of adjusting the beam axis. The process disclosed in JP-A-10-132920 is performed when the angle deviation with respect to a predetermined antenna angle occurs. Neither the process disclosed in JP-A-2004-156948 nor the process disclosed in JP-A-10-132920 detects an error of the antenna angle during adjusting the antenna angle. 
     SUMMARY 
     It is therefore a first object of at least one embodiment of the present invention to provide a radar device capable of avoiding a situation where a planar antenna becomes unable to move when performing the beam axis adjustment. 
     A second object of at least one embodiment of the present invention is to provide a technique capable of performing accurate adjustment to the target angle by preventing erroneous angle adjustment caused by the factors occurring during antenna angle adjustment. 
     In order to achieve at least one of the above-described objects, according to a first aspect of the embodiments of the present invention, there is provided a radar device comprising: a housing; a planar antenna tiltably provided with respect to the housing; a detecting section that detects a tilt angle of the planar antenna with respect to the gravity direction; a moving section that moves the planar antenna to adjust the tilt angle of the planar antenna; and a storage section that stores a history of the tilt angle of the planar antenna and a tiltable range of the planar antenna with respect to the housing, wherein the moving section moves the planar antenna by a first angle to adjust the tilt angle of the planar antenna to a reference angle if the sum of the history of the tilt angle of the planar antenna and the first angle is within the tiltable range of the planar antenna, and wherein the moving section does not move the planar antenna by the first angle if the sum of the history of the tilt angle of the planar antenna and the first angle is beyond the tiltable range of the planar antenna. 
     The history of the tilt angle may start from an initial value of a tilt angle of the planar antenna with respect to the housing. The detecting section may include an acceleration sensor provided in the planar antenna. Alternatively, the detecting section may include: a sensor provided in the housing, the sensor that detects a tilt angle of the housing with respect to the gravity direction; and a control section that detects the tilt angle of the planar antenna with respect to the gravity direction on the basis of the tilt angle of the housing and the history of the tilt angle of the planar antenna. The radar device may further comprise a control section that outputs a warning when the sum of the history of the tilt angle of the planar antenna and the first angle is beyond the tillable range of the planar antenna. The radar device may further comprise a control section that outputs a warning when the sum of the history of the tilt angle of the planar antenna and the first angle is within the tiltable range of the planar antenna and is beyond a predetermined threshold value. The moving section may include a deceleration mechanism that decelerates rotation of a motor to convert the rotation of the motor into a driving force of the planar antenna. 
     When the housing is mounted on a horizontal plane, the detecting section may detect an initial tilt angle of the planar antenna with respect to the gravity direction and the storage section may store the initial tilt angle. When the housing is then mounted on a vehicle, the detecting section may detect a secondary tilt angle of the planar antenna with respect to the gravity direction. If the sum of the initial tilt angle and the secondary tilt angle is within the tiltable range of the planar antenna, the moving section moves the planar antenna by the secondary tilt angle to adjust the tilt angle of the planar antenna to the reference angle and the storage section stores the secondary tilt angle. If the sum of the initial tilt angle and the secondary tilt angle is beyond the tiltable range of the planar antenna, the moving section does not move the planar antenna by the secondary tilt angle. When the housing is then moved, the detecting section may detect a tertiary tilt angle of the planar antenna with respect to the gravity direction. If the sum of the initial tilt angle, the secondary tilt angle and the tertiary tilt angle is within the tiltable range of the planar antenna, the moving section moves the planar antenna by the tertiary tilt angle to adjust the tilt angle of the planar antenna to the reference angle and the storage section stores the tertiary tilt angle. If the sum of the initial tilt angle, the secondary tilt angle and the tertiary tilt angle is beyond the tiltable range of the planar antenna, the moving section does not move the planar antenna by the tertiary tilt angle. 
     According to the first aspect of the embodiments of the present invention, it is possible to avoid the situation where the planar antenna becomes unable to move when performing the beam axis adjustment. 
     According to a second aspect of the embodiments of the present invention, there is provided a radar device comprising: a tilt angle detecting section that detects a tilt angle of an antenna with respect to a target angle; an adjusting section that adjusts an angle of the antenna from the tilt angle to the target angle; a calculating section that calculates an estimation value which is a criterion for determining whether or not an adjustment from the tilt angle to the target angle is performed as planned; a measurement value detecting section that detects a measurement value in accordance with variation in the angle of the antenna during the adjustment from the tilt angle to the target angle; and an adjustment failure detecting section that detects a failure of the adjustment on the basis of an error between the estimation value and the measurement value. 
     The estimation value may include estimation angles of the antenna for every predetermined time, and the measurement value may include measurement angles of the antenna for every predetermined time. 
     The estimation value may include an estimation time to complete the adjustment, and the measurement value may include a measurement time to complete the adjustment. 
     The estimation value may include estimation angles of the antenna for every predetermined time and an estimation time to complete the adjustment, the measurement value may include measurement angles of the antenna for every predetermined time and a measurement time to complete the adjustment, and the adjustment failure detecting section may detect the failure of the adjustment on the basis of an error between the estimation angles and the measurement angles for every predetermined time and an error between the estimation time and the measurement time. 
     The radar device may further comprise a notifying section that notifies that the error exceeds a predetermined range. 
     According to a second aspect of the embodiments of the present invention, there is provided a method for adjusting an angle of an antenna, comprising: detecting a tilt angle of the antenna with respect to a target angle; adjusting the angle of the antenna from the tilt angle to the target angle; calculating an estimation value which is a criterion for determining whether or not the adjusting of the angle of the antenna from the tilt angle to the target angle is performed as planned; detecting a measurement value in accordance with variation in the angle of the antenna during the adjusting of the angle of the antenna from the tilt angle to the target angle; and detecting a failure of the adjusting on the basis of an error between the estimation value and the measurement value. 
     According to the second and third aspects of the embodiments of the present invention, the adjustment of the angle of the antenna is performed while detecting the error between the estimation value and the measurement value in accordance with the angle variation of the antenna, it is possible to prevent the failure of the adjustment caused by factors occurring during the adjustment. As a result, accurate angle adjustment to the target angle can be performed. 
     In addition, it is possible to finely check the angle of the antenna for every time during the adjustment by performing the adjustment of the angle of the antenna while detecting the error between the estimation angles of the antenna and the measurement angles of the antenna. As a result, accurate angle adjustment to the target angle can be performed. 
     In addition, it is possible to prevent the failure of the adjustment caused by the adjustment time difference by detecting the error between the estimation time from the start of the adjustment to the completion of the adjustment and the measurement time from the start to the completion. As a result, accurate angle adjustment to the target angle can be performed. 
     In addition, when the error exceeds a predetermined range, an alarm is given to the worker in a vehicle factory, a dealer, or the like. As a result, since a malfunction of the radar device can be prevented in advance, safe vehicle control can be provided for the user who uses the vehicle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings: 
         FIG. 1A  is a perspective view illustrating a radar device; 
         FIG. 1B  is a cross-sectional view illustrating the radar device shown in  FIG. 1A ; 
         FIG. 2A  is a cross-sectional view illustrating the radar device shown in  FIG. 1A  in a state where the tilt angle of the housing is α′; 
         FIG. 2B  is a cross-sectional view illustrating the radar device shown in  FIG. 1A  in a state where the tilt angle of the housing is β°; 
         FIG. 3  is a schematic view illustrating a radar device according to a first embodiment of the present invention in a state where the radar device is installed on a vehicle; 
         FIG. 4  is a cross-sectional view illustrating an internal structure of the radar device according to the first embodiment; 
         FIG. 5  is a block diagram illustrating a configuration of the radar device according to the first embodiment; 
         FIGS. 6A to 6C  are schematic views each illustrating the housing for explaining the tilt angle of the housing with respect to the gravity direction; 
         FIGS. 6D to 6F  are schematic views each illustrating the planar antenna for explaining the tilt angle of the planar antenna with respect to the gravity direction; 
         FIGS. 7A to 7C  are schematic views each illustrating the radar device for explaining the beam axis adjustment; 
         FIG. 8  is a flow chart illustrating operation procedures of the radar device in a state shown in  FIG. 7A ; 
         FIG. 9  is a flow chart illustrating operation procedures of the radar device in states shown in  FIGS. 7B and 7C ; 
         FIG. 10  is a flow chart illustrating operation procedures of beam axis readjustment in a preferable embodiment; 
         FIG. 11  is a perspective view illustrating a radar device according to a second embodiment of the present invention; 
         FIG. 12  is a schematic view illustrating the radar device according to the second embodiment in a state where the radar device is installed on a vehicle; 
         FIG. 13  is a cross-sectional view illustrating an internal structure of the radar device according to the second embodiment; 
         FIG. 14  is a block diagram illustrating a configuration of the radar device according to the second embodiment; 
         FIG. 15  is an explanatory diagram of an angle error occurring at the time of an antenna angle adjustment; 
         FIG. 16  is an explanatory diagram of an adjustment time error occurring at the time of the antenna angle adjustment. 
         FIG. 17  is a flow chart illustrating the first antenna angle adjustment processing; 
         FIG. 18  is a flow chart illustrating the second antenna angle adjustment processing; and 
         FIG. 19  is a flow chart illustrating the third antenna angle adjustment processing. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, embodiments of the invention will be described with reference to the accompanying drawings. However, the technical scope of the invention is not limited to these embodiments, but the subject matter defined by the appended claims and their equivalents are also included in the technical scope of the invention. 
     First Embodiment 
       FIG. 3  is a schematic view illustrating a radar device according to a first embodiment of the present invention in a state where the radar device is installed on a vehicle.  FIG. 3  shows an attachment position of the radar device  10  to the vehicle  1  when the radar device  10  scans the front side of the vehicle  1 . The radar device  10  is attached in a front bumper or a front grille of the vehicle  1 . The radar device  10  transmits a radar signal to the space in front of the vehicle  1  through the front grille or a decorative panel on the front surface of the front bumper and receives a reflected signal from the target. The radar device  10  detects the target located in the front space of the vehicle  1  by processing the transmitted and received signals. 
     The targets to be detected are mainly located on the same horizontal plane as the vehicle  1 , such as other vehicles, pedestrians, or objects placed on the road. Accordingly, in order to detect those targets with high precision, it is preferable to direct the beam axis toward the reference direction in which the reception gain of the reflected signal from the target becomes largest. For this reason, when installing the radar device  10  on the vehicle  1  or at the time of subsequent vehicle checking, maintenance, the beam axis adjustment is performed so that the beam axis directs toward the reference direction. Here, the reference direction is a horizontal direction. Alternatively, the reference direction may be arbitrarily set by simulation or experiment. For example, the reference direction may be set to be low by about 0.5° from the horizontal direction. 
     The radar device  10  outputs the information on the detected target to a vehicle control device  100  of the vehicle  1 . The vehicle control device  100  performs behavior control of the vehicle  1  on the basis of the target information detected by the radar device  10 . For example, the vehicle control device  100  performs a travel control for following a preceding vehicle, a collision avoiding control for avoiding collision with an opposite vehicle, a pedestrian, and an object placed at the road, or the collision response control. 
     The radar device  10  may be attached to various positions of the vehicle  1  other than the example shown in  FIG. 3 . For example, when scanning the front side of the vehicle  1 , the radar device  10  is attached in a fog lamp unit provided in a front side portion of the vehicle  1  and scans the space in front of the vehicle  1  to detect a target. When scanning the rear or the rear side, the radar device  10  is attached on the front surface or the side surface edge in a rear bumper of the vehicle  1 , a tail lamp unit provided in a rear side portion, or the like and scans a space in the rear or the rear side of the vehicle  1  to detect a target. In any case, the beam axis adjustment is performed so that the beam axis directs toward the reference direction. 
     The radar device  10  in the embodiment has the housing  11  and the planar antenna  14 , which is housed in the housing  11  and is tiltably provided with respect to the housing  11 . The housing  11  is fixed to the vehicle  1  by fixtures  13 . The tilt angle of the planar antenna  14  with respect to the gravity direction (the antenna angle of the planar antenna  14 ) can be changed by moving the planar antenna  14  relative to the housing  11  in a state where the housing  11  is attached to the vehicle  1 , and the beam axis adjustment is performed so that the beam axis directs toward the reference direction. 
       FIG. 4  is a cross-sectional view illustrating an internal structure of the radar device  10 .  FIG. 5  is a block diagram illustrating a configuration of the radar device  10 . The configuration of the radar device  10  will be described in detail with reference to  FIGS. 4 and 5 . 
     As described above, the radar device  10  has the planar antenna  14  and various electronic circuits which are housed in the rectangular housing  11 . A radome  11   a  is provided in a front portion of the housing  11 . 
     An array or a patch is provided on the front surface of the planar antenna  14 , and one end  14   a  of the planar antenna  14  is attached to the housing  11  through a tilting shaft  15  and the other end  14   b  is rotatably engaged with a sliding shaft  18   a  with a pin  20  in a state where the front surface is directed toward the front. The planar antenna  14  transmits a radar signal forward through the radome  11   a . In this case, a beam axis is formed in a perpendicular direction (or approximately perpendicular direction) of the planar antenna  14 . 
     The antenna moving section  18  has a sliding shaft  18   a  whose front end is engaged with the end  14   b  of the planar antenna  14  with the pin  20  and which is slidable back and forth, a motor  18   b  comprised of a DC motor or the like, and a deceleration mechanism  18   d  which decelerates a rotational motion of a shaft  18   c  of the motor  18   b  at the predetermined rate in order to convert the rotational motion into a sliding motion of the sliding shaft  18   a . As an example, the deceleration mechanism  18   d  has a worm gear attached to the shaft  18   c  and a worm wheel to which the torque of the worm gear is transferred to slide the sliding shaft  18   a . However, the deceleration mechanism  18   d  is not limited to such a structure as long as the deceleration mechanism  18   d  can convert the torque of the shaft  18   c  of the motor  18   b  into the sliding motion of the sliding shaft  18   a.    
     The antenna moving section  18  slides the sliding shaft  18   a  forward/backward by performing positive rotation/negative rotation of the motor  18   c . If the sliding shaft  18   a  slides forward/backward, the end  14   b  of the planar antenna  14  moves forward/backward. As a result, since the end  14   b  of the planar antenna  14  moves forward/backward around the tilting shaft  15 , the antenna angle is adjusted. 
     An antenna angle detecting section  16  and a transmission and reception circuit  22  are provided on the back surface of the planar antenna  14 . The antenna angle detecting section  16  is comprised of a tilt sensor such as an acceleration sensor, and detects the antenna angle of the planar antenna  14 .  FIG. 4  shows a state where the antenna angle is 0° with respect to the gravity direction. The transmission and reception circuit  22  is comprised of an oscillator which generates a radar signal (an electromagnetic wave) with a millimeter wavelength, as a main component, and supplies the radar signal to the planar antenna  14  and generates a beat signal by processing a reception signal of the planar antenna  14 . 
     A control section  26  is provided behind the planar antenna  14  in the housing  11 . The control section  26  is comprised of a motor driver and a microcomputer which includes a CPU (Central Processing Unit), a ROM (Read Only Memory; for example, a rewritable nonvolatile storage medium), and a RAM (Random Access Memory). The control section  26  controls operations of other sections by making the CPU execute a control program stored in the ROM using the RAM as a working area. Moreover, the ROM corresponds to a storage section  27  and stores various kinds of information required for control operation of the control section  26 , which will be described in detail later. 
     The control section  26  controls an operation of the transmission and reception circuit  22  and detects the target on the basis of a beat signal generated by the transmission and reception circuit  22 . 
     The control section  26  controls the driving of the motor  18   b  in the antenna moving section  18 . In this case, the control section  26  acquires the antenna angle from a signal indicating the antenna angle, which is input from the antenna angle detecting section  16 , and calculates the driving amount corresponding to a planned tilt angle and transmits it to the antenna moving section  18 . 
     The control section  26  is connected to an in-vehicle network  30  of the vehicle  1 . Through the in-vehicle network  30 , the control section  26  can communicate with the vehicle control device  100 , a display unit  110 , and an operation input unit  120  which are installed on the vehicle  1 . 
     The display unit  110  displays a message showing the warning transmitted from the control section  26  of the radar device  10 , which will be described later. For example, the display unit  110  is comprised of a display device provided on an instrument panel of the vehicle  1  or an external information processing apparatus (for example, a personal computer) connected to the in-vehicle network  30 . 
     The operation input unit  120  inputs a control signal which instructs the beam axis adjustment to the control section  26  of the radar device  10 . For example, the operation input unit  120  is comprised of an ignition key of the vehicle  1 , an electronic apparatus (for example, an in-vehicle electronic apparatus with a navigation function and/or an audio function) connected to the in-vehicle network  30 , or a personal computer or an operation terminal provided outside the vehicle  1 . 
     In the radar device  10  configured as described above, the beam axis adjustment is performed by controlling the antenna moving section  18  to move the planar antenna  14  so as to set the antenna angle to a reference antenna angle while monitoring the antenna angle by the control section  26  when the radar device  10  is installed on the vehicle. In this case, the control section  26  detects the antenna angle and calculates the driving amount corresponding to a planned tilt angle and then drives the antenna moving section  18 . Then, the control section  26  detects the antenna angle again when the driving corresponding to the calculated driving amount ends and the control section  26  drives the antenna moving section  18  again for error correction. Alternatively, the driving amount may be controlled while performing feedback of the antenna angle in a predetermined period. 
     Here, if the forward tilt angle of the planar antenna  14  with respect to the housing  11  reaches a predetermined value, the planar antenna  14  comes in contact with the inner wall of the radome  11   a  and the sliding shaft  18   a  becomes unable to slide. As a result, the movement of the planar antenna  14  may be obstructed. On the contrary, if the backward tilt angle of the planar antenna  14  with respect to the housing  11  reaches a predetermined value, an engaged portion between the planar antenna  14  and the sliding shaft  18   a  comes in contact with the deceleration mechanism  18   d  or a rear end of the sliding shaft  18   a  comes in contact with the inner wall of the housing  11  on the back side and the sliding shaft  18   a  becomes unable to slide. As a result, the movement of the planar antenna  14  may be obstructed. In both the cases, if the sliding of the sliding shaft  18   a  is obstructed and the abnormal engagement occurs in the deceleration mechanism  18   d , the deceleration mechanism  18   d  is fixed so that the sliding shaft  18   a  cannot slide any more. As a result, the planar antenna  14  becomes unable to move. 
     Therefore, a tiltable range θ of the planar antenna  14  which does not lead to the above situations is set in advance, and the planar antenna  14  is moved within the range. However, if the tilt angle of the housing  11  in the back and forth direction when performing the beam axis adjustment reaches a predetermined value, there is a possibility that the planar antenna  14  will be tilted exceeding the tillable range θ when the control section  26  control the antenna moving section  18  to move the planar antenna  14  while monitoring the antenna angle. Particularly when the tilt angle of the housing  11  significantly changes by vibration from the road surface during traveling or contact or collision with other vehicles, obstacles, after the first-time beam axis adjustment, the probability that the movement of the planar antenna  14  will exceed the tiltable range θ in the beam axis readjustment increases. 
     Therefore, the radar device  10  in the present embodiment stores a history of the tilt angle of the planar antenna  14  whenever performing the beam axis adjustment, and checks whether or not the movement can be performed within the tiltable range θ of the planar antenna  14  with respect to the housing  11  on the basis of the history when performing a new beam axis adjustment. Then, the planar antenna  14  is moved to adjust the antenna angle when it is checked that the movement can be performed within the tiltable range θ and the planar antenna  14  is not tilted if it is not checked that the movement cannot be performed within the tiltable range θ. In this way, even if the tilt angle of the housing  11  is significantly changed before the beam axis readjustment, it is possible to prevent the planar antenna  14  from moving by an angle exceeding the tiltable range θ. As a result, it is possible to avoid the situation where the abnormal engagement occurs in the deceleration mechanism  18   d  and the planar antenna  14  become unable to move. 
     If a sufficiently large space can be ensured in the housing  11 , the situation where the planar antenna  14  cannot move can be avoided to some extent. However, according to the present embodiment, since it is not necessary to enlarge the housing  11 , the radar device can be reduced in size. 
     Here, an operation of the radar device  10  according to the first embodiment will be described with reference to  FIGS. 6A to 10  in each case of the initial setting, the first-time beam axis adjustment, and the beam axis readjustment. 
     Hereinbelow, for the sake of convenience, the tilt angle to the front side is expressed as a positive value and the tilt angle to the rear side is expressed as a negative value. In order to make the following explanation easily understood, the tilt angle of the housing  11  with respect to the gravity direction, the antenna angle (the tilt angle of the planar antenna  14  with respect to the gravity direction), a tillable range of the planar antenna  14 , and an angle by which the planar antenna  14  moves are shown in  FIGS. 6A to 6F . 
     Assuming that the tilt angle of the housing  11  is 0° when the direction of the housing  11  matches the gravity direction ( FIG. 6A ), the tilt angle of the housing  11  is α° (&gt;0°) when the housing  11  is inclined forward ( FIG. 6B ), and −α° when the housing  11  is inclined backward ( FIG. 6C ). Assuming that the antenna angle of the planar antenna  14  is 0° when the direction of the planar antenna  14  matches the gravity direction ( FIG. 6D ), the antenna angle of the planar antenna  14  is α° (&gt;0) when the planar antenna  14  is inclined forward ( FIG. 6E ), and −α° when the planar antenna  14  is inclined backward ( FIG. 6F ). Moreover, as shown in  FIG. 6D , the tiltable range 0 of the planar antenna  14  (&gt;0) is set in the back and forth direction with the gravity direction from the tilting shaft  15  as a reference in a state where the housing  11  is placed on the horizontal plane. That is, the tillable range θ includes a rear angle range of (θ/2)° with respect to the front side and a front angle range of (−θ/2)° with respect to the rear side. The tiltable range θ may be set as an arbitrary value according to design. 
     In the beam axis adjustment, the planar antenna  14  is moved by an angle to adjust the antenna angle (the tilt angle of the planar antenna  14  with respect to the gravity direction) to the reference antenna angle (i.e. 0°). The angle by which the planar antenna  14  is moved in the beam axis adjustment is 0° when the antenna angle detected by antenna angle detecting section  16  is 0° ( FIG. 6D ), the angle is α° (that is, α° forward) when the detected antenna angle is α° ( FIG. 6E ), and the angle is −α° (that is, α° backward) when the detected antenna angle is −α° ( FIG. 6F ). 
     Hereinafter, for convenience of explanation, angles in the front direction expressed as positive values are exemplified as the tilt angle of the housing  11 , the antenna angle and the angle by which the planar antenna  14  is moved in the beam axis adjustment. However, the following explanation is applied by setting the angle in the back direction as a negative value. 
       FIGS. 7A to 7C  are schematic views each illustrating the radar device  10  for explaining the beam axis adjustment.  FIG. 7A  shows a state of the radar device  10  when the initial setting is performed.  FIG. 7B  shows a state of the radar device  10  when the radar device  10  is installed on the vehicle  1  and the first-time beam axis adjustment is performed.  FIG. 7C  shows a state of the radar device  10  when the beam axis readjustment is performed.  FIGS. 7A to 7C  also show content of operation processing of the control section  26  and information stored in the storage section  27  in each case of the initial setting, the first-time beam axis adjustment, and the beam axis readjustment. 
       FIG. 8  is a flow chart illustrating the operation procedures of the radar device  10  in the state shown in  FIG. 7A .  FIG. 9  is a flow chart illustrating the operation procedures of the radar device  10  in the states shown in  FIGS. 7B and 7C . 
     First, the initial setting of the radar device  10  will be described with reference to  FIGS. 7A and 8 . This operation is executed, for example, in a test process before shipping of the radar device  10 . 
     As shown in  FIG. 7A , the housing II is placed on the horizontal plane. In this state, the tilt angle of the housing  11  with respect to the gravity direction is 0°. On the other hand, the initial value of the antenna angle is α1°. This is due to the manufacture error of each radar device  10 . The initial value α1° of the antenna angle is equal to 0° if it is as designed. 
     In this state, a control signal which instructs the initial setting is input from the operation input unit  120  to the control section  26  (S 2 ). In response to the control signal, the control section  26  acquires the initial value α1° of the antenna angle detected by the antenna angle detecting section  16  (S 4 ) and stores the initial value α1° of the antenna angle in the storage section  27  (S 6 ). The storage section  27  also stores the number of times of the beam axis adjustment. Here, the number of times of beam axis adjustment is still 0 which is an initial value. In this manner, the initial setting operation is performed. 
     Next, the first-time beam axis adjustment of the radar device  10  will be described with reference to  FIGS. 7B and 9 . This first-time beam axis adjustment is performed, for example, in a test process after installing various electric components in a vehicle assembly process, in a state where the vehicle  1  is placed on the horizontal plane. 
     In  FIG. 7B , the housing  11  is installed in the vehicle  1 . In this state, the tilt angle of the housing  11  with respect to the gravity direction is α2°. This is due to an error during the installation work. The antenna angle is β1° (here, β1° corresponds to the sum of the initial value α1° and the tilt angle α2° of the housing  11 ). 
     In this state, a control signal which instructs the first-time beam axis adjustment is input from the operation input unit  120  to the control section  26  (S 10 ). In response to the control signal, the control section  26  acquires the antenna angle β1° detected by the antenna angle detecting section  16  (S 12 ). Here, a planned tilt angle by which the planar antenna  14  is to be moved is β1°. 
     Then, the control section  26  reads the tillable range θ of the planar antenna  14  and the history of the tilt angle of the planar antenna  14  from the storage section  27  (S 14 ). Here, the antenna angle of α1° stored last time and the number of times of the beam axis adjustment of 0 are read as the history of the tilt angle. 
     Next, the control section  26  checks whether or not the antenna angle exceeds the tiltable range θ if the planar antenna  14  is moved by the planned tilt angle of β1°. In other words, the control section  26  determines whether the sum of the history of the tilt angle of the planar antenna  14  and the planned tilt angle β1° is within the tiltable range θ of the planar antenna  14  or beyond the tiltable range θ of the planar antenna  14 . As a specific operation, a possible tilt angle is calculated by subtracting the history of the tilt angle from the tiltable range θ (S 16 ). In consideration of the stopping accuracy of the planar antenna  14  by the antenna moving section  18 , (α+nδ)° is derived as the history of the tilt angle of the planar antenna  14 . Here, n is the number of times of the past beam axis adjustment, δ is an error caused by overrunning of the planar antenna  14 . Accordingly, [θ−(α+nδ)]° is derived as the possible tilt angle. 
     The control section  26  then checks whether or not the planned tilt angle β1° exceeds the possible tilt angle. That is, it is checked whether or not θ−(α1+nδ)&gt;β1 is satisfied (S 18 ). As shown in  FIG. 7B , even if the planar antenna  14  is moved by the planned tilt angle β1°, the planar antenna  14  is in the tiltable range θ, and thus the determination result in the procedure S 18  is YES. In this way, it is determined that the sum of the history (α1+nδ) and the planned tilt angle β1° is within the tiltable range θ. Accordingly, the control section  26  controls the antenna moving section  18  to move the planar antenna  14  by the angle β1° to adjust the antenna angle to the reference antenna angle (S 20 ) in order to direct the beam axis toward the reference direction. The control section  26  then stores the history of the tilt angle of the planar antenna  14  (S 22 ). That is, the control section  26  stores the value of (α1β1)° in the storage section  27  and increments the number of times of the beam axis adjustment by 1. In this manner, the first-time beam axis adjustment is executed. 
     Next, the beam axis readjustment of the radar device  10  will be described with reference to  FIGS. 7C and 9 . This beam axis readjustment is performed, for example, in the checking and repair process for the vehicle  1  after the first-time beam axis adjustment, in a state where the vehicle  1  is placed on the horizontal plane. 
     In  FIG. 7C , the tilt angle of the housing  11  with respect to the gravity direction is changed into γ° (&gt;α2°). This is due to the vibration from the road surface during traveling or contact or collision with other vehicles and the like. When the tilt angle of the housing  11  is γ°, the antenna angle is also γ°, since the first-time beam axis adjustment has been performed when installing the radar device  10  in the vehicle  1 . 
     In this state, a control signal which instructs the beam axis readjustment is input to the control section  26  (S 10 ). In response to the control signal, the control section  26  acquires the antenna angle γ° detected by the antenna angle detecting section  16  (S 12 ). Here, a planned tilt angle by which the planar antenna  14  is to be moved is γ°. 
     Then, the control section  26  reads the tiltable range θ of the planar antenna  14  and the history of tilt angle of the planar antenna  14  is read from the storage section  27  (S 14 ). Here, the value of (α1+β1)° and the number of times of beam axis adjustment (i.e. 1) are read as the history of the tilt angle. 
     Next, the control section  26  calculates the possible tilt angle (S 16 ) and checks whether or not the planned tilt angle γ° exceeds the possible tilt angle (S 18 ). That is, it is checked whether or not θ−(α1+β1+nδ)&gt;γ is satisfied. In this way, it is determined whether the sum of the history (α1+β1+nδ) and the planned angle γ° is within the tiltable range θ or beyond the tiltable range θ. 
     If the determination result in the procedure S 18  is YES, the control section  26  controls the antenna moving section to move the planar antenna  14  by the angle γ° to adjust the antenna angle to the reference antenna angle (S 20 ) and stores, the value of (α1+β1+γ)° in the storage section  27  and increment the number of times of the beam axis adjustment by 1 (S 22 ). In this manner, the beam axis readjustment is executed. In addition, even when the beam axis readjustment is executed again and again, the same procedures as above are executed if the planar antenna  14  can be moved within the tiltable range θ. In each case, the history of the tilt angle of the planar antenna  14  is updated and stored in the storage section  27 . 
     In  FIG. 7C , however, the antenna angle exceeds the tiltable range θ if the planar antenna  14  is moved by the planned tilt angle of γ°. In other words, it is determined that the sum of the history of tilt angle (α1+β1+nδ) and the planned tilt angle γ° is beyond the tiltable range θ. Accordingly, in this case, the determination result in the procedure S 18  is NO. Accordingly, the control section  26  ends the processing of the beam axis readjustment and the antenna moving section does not move the planar antenna  14  by the planned tilt angle γ°. In this way, it is possible to prevent a situation where the planar antenna  14  comes in contact with the inner wall of the housing  11  and cannot return to the original state. Preferably, before ending the processing, a warning message is output to the display unit  110  (S 24 ). In this situation, it is likely that the tilt angle of the housing  11  is significantly changed because a fixture that attaches the housing  11  to the vehicle  1  may have a problem or a vehicle body of the vehicle  1  may be deformed. Thus, by displaying the warning massage on the display unit  110 , it is possible to encourage the driver or the worker to perform the adjustment of the fixture of the housing  11  or the maintenance of the vehicle body. 
       FIG. 10  is a flow chart illustrating the operation procedures of the beam axis readjustment in a preferable embodiment. In  FIG. 10 , procedures  19   a ,  19   b , and  19   c  are added between the procedures S 18  and  520  in the flow chart shown in  FIG. 9 . Even if it is determined that the planned tilt angle is smaller than the possible tilt angle (YES in S 18 ), when the planned tilt angle exceeds a predetermined threshold value (YES in S 19   a ), the control section  26  outputs a warning message (S 19   b ). With this configuration, the defect of the vehicle body of the vehicle  1  can be detected early, it is possible to encourage the driver or the worker to perform the maintenance of the vehicle  1 . In this case, however, if an instruction to continue the movement of the planar antenna  14  is input (YES in S 19   c ), the beam axis adjustment is executed (S 20 ). Since the beam axis adjustment can be executed as described above, the beam axis adjustment can be completed while warning of the possibility of a problem in the vehicle body. As a result, user convenience can be improved. 
     In addition, the threshold value may change with the number of times of the beam axis adjustment. That is, the threshold value may be set to a relatively large value when installing the radar device  10  in the vehicle  1 , so that the tilt angle of the housing  11  occurring by manual operation can be covered. Moreover, the threshold value may also be set to a smaller value than the original value at the time of the beam axis readjustment, so that it can be checked whether or not the planned tilt angle is in the fine adjustment range in the beam axis readjustment and it is possible to quickly detect that a problem has occurred in the fixture of the housing  11  or the vehicle body if the planned tilt angle is not in the fine adjustment range. 
     The antenna angle detecting section may be realized by providing a sensor which detects the tilt angle of the housing  11  with respect to the gravity direction instead of providing the antenna angle detecting section  16  which detects the tilt angle of the planar antenna  14  with respect to the gravity direction (the antenna angle). In this instance, the control section  26  can calculate the antenna angle on the basis of the history of tilt angle of the planar antenna  14  and the tilt angle of the housing  11  detected by the sensor. 
     The detection procedure of the antenna angle in this case will be described with reference to  FIGS. 7A to 7C . In  FIG. 7A , since the housing  11  is placed on the horizontal plane, the tilt angle of the housing  11  is 0°. Accordingly, the designed initial value α1° (preferably, 0°) is detected as the antenna angle. In  FIG. 7B , since the tilt angle of the housing  11  is α2°, (α2+α1)° is detected as the antenna angle. In  FIG. 7C , since the tilt angle of the housing  11  is γ°, (γ−β1)° is detected as the antenna angle. Also in this modification, it is possible to avoid the situation where the antenna angle cannot be adjusted at the time of the beam axis adjustment. 
     In the above explanation, the planar antenna  14  is tiltably provided with respect to the housing  11  through the tilting shaft  15 . The attachment structure of planar antenna  14  to the housing  11  is not limited thereto. For example, one end of the planar antenna  14 , which is to be attached to the housing  11  may be bent such that the planar antenna  14  can be tiltably provided with respect to the housing  11  without using the tilting shaft. 
     Moreover, in the above explanation, the case is shown in which the tilt angle of the housing  11  continuously changes in the forward direction and accordingly, the planar antenna  14  is moved forward. However, the above explanation may also be applied to the case in which the tilt angle of the housing  11  continuously changes backward and accordingly, the planar antenna  14  is moved backward. Moreover, for example, even in the case where the housing  11  is inclined forward and is then inclined backward or in the opposite case, the possible tilt angle can be calculated by subtracting the sum of the history of tilt angle stored in the storage section  27  from the tiltable range as described above. 
     As described above, according to the first embodiment, it is possible to avoid the situation where the planar antenna cannot be moved at the time of the beam axis adjustment. As a result, it is possible to improve the working efficiency at the time of the beam axis adjustment and to improve the user convenience without enlarging the housing of the radar device. 
     Second Embodiment 
     1. System Configuration 
       FIG. 11  is a perspective view illustrating a radar device  102  which performs an antenna adjustment. The radar device  102  has a housing  112  and an antenna  114  provided in the housing  112 . The housing  112  is fixed to a vehicle body by a fixing bolt  113 . Moreover, in the second embodiment, it is assumed that the beam axis direction of the antenna  114  is parallel to the horizontal plane f 1  when the antenna surface of the antenna  114  is perpendicular to the horizontal plane g 1  in a state where the radar device  102  is located in parallel with the horizontal plane g 1 . In addition, the following explanation will be given assuming the case, in which the beam axis direction is parallel to the horizontal plane f 1  in such a state where the radar device  102  is located in parallel with the horizontal plane g 1 , as the target angle of the antenna  114  at which a reflected wave from an object can have a reflection intensity equal to or larger than a fixed value. 
     The antenna  114  is comprised of a planar antenna, such as a patch antenna or an array antenna with antenna elements arrayed on the front surface. The antenna  114  forms a beam axis direction in the perpendicular direction (parallel to the horizontal plane) of the antenna  114  through a radome  115  so that a transmission wave is transmitted and a reflected wave from an object is received. In addition, the antenna  114  may adjust the antenna angle so that the reflected wave on the object of the transmission wave is received with predetermined reflection intensity. Details of the adjustment of the antenna angle will be described later. 
       FIG. 12  is a schematic view illustrating the radar device  102  installed on the vehicle  101 . In the second embodiment, the radar device  102  is installed on the vehicle  101  in a state of being inclined by an angle of θ 1  from the horizontal plane g 1  due to the skill of a worker or the installation space of the radar device  102  which changes with the type of the vehicle  101  in which the radar device  102  is installed. Therefore, the antenna angle also corresponds to a beam axis b 2  which is a beam axis direction with a tilt angle of the antenna inclined by θ 1  from a beam axis b 1  that is a beam axis direction parallel to the horizontal plane. 
     As a result of the tilt angle of the antenna, the angle of the antenna  114  does not become a beam axis direction in which the reflection intensity equal to or larger than a fixed value can be obtained for the object. In addition, the reflection intensity equal to or larger than the fixed value referred to herein means a reflection intensity with which the distance, the relative velocity, and the angle of an object existing in the detection range of the radar device  102  can be detected. 
     Next, the configuration in which the angle of the antenna  114  is adjusted from the antenna angle before adjustment to the target angle will be described.  FIG. 13  is a cross-sectional view illustrating an internal structure of the radar device  102  taken along a line III-III shown in  FIG. 11 .  FIG. 14  is a block diagram illustrating a configuration of the radar device  102 . 
     One end of the antenna  114  is connected to the housing  112  through a tilting shaft  122  so as to be able to tilt, and the other end of the antenna  114  is connected to a sliding shaft  118   c  through a pin  120  so as to be rotatable. An adjustment section  118  which changes the angle of an antenna is configured to include a motor  118   a , a deceleration mechanism  118   b  which decelerates the rotating speed of the motor  118   a  at the predetermined rate and converts the rotational motion into reciprocating driving of the sliding shaft  118   c , and the sliding shaft  118   c.    
     When the adjustment section  118  drives the sliding shaft  118   c  to reciprocate as shown by arrow D 2 , the end of the antenna  114  tilts around the tilting shaft  122  as shown by arrow D 1  according to the reciprocation of the sliding shaft  118   c . As a result, the antenna angle changes such that the angle adjustment is performed. 
     An antenna angle detecting section  126  which detects the angle of the antenna  114  is provided on the back surface of the antenna  114 . Examples of the antenna angle detecting section  126  include a tilt sensor and a yaw rate sensor. In addition, a transmission and reception circuit  124 , which generates a transmission signal of a transmission wave output from the antenna  114  and supplies the transmission signal to the antenna element and which processes the received signal from the antenna element, is provided on the back surface of the antenna  114 . 
     In addition, a control section  116  that controls the radar device  102  and that includes a motor driver and a microcomputer, which includes a CPU (Central Processing Unit)  116   a  that performs object detection processing, a ROM (Read Only Memory)  116   b  that stores data required for the CPU  116   a  to perform the object detection processing, and a RAM (Random Access Memory)  116   c  that temporarily stores the data when performing the object detection processing, is provided in the housing  112 . The control section  116  instructs the adjustment section  118  to drive the motor and determines the amount of driving. 
     The amount of driving is determined on the basis of the angle difference between the target angle and the antenna angle before adjustment after the CPU  116   a  reads the target angle of the antenna  114  stored beforehand in the ROM  116   b  and detects the antenna angle before adjustment input from the antenna angle detecting section  126 . 
     The control section  116  controls the operation of the transmission and reception circuit  124  in the object detection processing and detects the information, such as the position, the relative velocity, and the angle of the object, on the basis of the transmission and reception signals of the antenna  114  processed by the transmission and reception circuit  124 . Then, the control section  116  transmits the detected object information to a vehicle control device  130  which is electrically connected with the control section  116 . 
     Moreover, in the angle adjustment of an antenna, the control section  116  detects the antenna angle before adjustment using the antenna angle detecting section  126  and reads the target angle from the memory  116   b  in the control section  116 . In addition, from the information of the antenna angle before adjustment and the target angle, the control section  116  calculates the antenna estimation angle for every time which is a criterion for determining whether or not planned adjustment from the antenna angle before adjustment to the target angle is performed. In addition, the control section  116  detects an error between the antenna estimation angle, which is an adjustment estimation value, and an antenna angle for every time while adjustment from the antenna angle before adjustment to the target angle is being performed. 
     Moreover, in the angle adjustment of the antenna  114 , the control section  116  detects the antenna angle before adjustment using the antenna angle detecting section  126  and reads the target angle from the ROM  116   b  in the control section  116 . In addition, from the information of the antenna angle before adjustment and the target angle, the control section  116  calculates an adjustment completion estimation time which is a criterion for determining whether or not the adjustment to the target angle is performed as planned. In addition, the control section  116  detects an error between the adjustment completion estimation time, which is an adjustment estimation value, and an adjustment completion time from the antenna angle before adjustment to the target angle. 
     Moreover, when the allowable error range set beforehand is exceeded in the antenna angle adjustment, the control section  16  notifies the user that an angle adjustment error has occurred by operating a warning device provided inside or outside the radar device  102  and also transmits to the adjustment section  118  a signal for stopping the angle adjustment of the antenna  114 . 
     The vehicle control device  130  is electrically connected to the control section  116  and makes instructions to execute various kinds of vehicle control, such as a brake operation or an accelerator operation, for various vehicle apparatuses. The vehicle control device  130  is communicably connected with a test terminal  140 , such as a personal computer. 
     The test terminal  140  transmits an instruction for starting antenna angle adjustment to the control section  116  of the radar device  102  through the vehicle control device  130  at the time of antenna angle adjustment or serves as a display device which displays a situation of the antenna angle adjustment for the user. In addition, the test terminal  140  may perform the error detection processing of the antenna angle or the like for every time while adjustment from the antenna angle before adjustment to the target angle is being performed or the processing of detecting the error between the adjustment completion estimation time, which is the adjustment estimation value, and the adjustment completion time from the antenna angle before adjustment to the target angle, which is performed when the control section  116  performs antenna angle adjustment. 
     2. Error Detection in Antenna Angle Adjustment 
     Next, specific processing of detecting an error in angle adjustment will be described.  FIG. 15  is an explanatory diagram showing a state where an angle error occurs at the time of antenna angle adjustment. For example,  FIG. 15  is a graph showing that an adjustment error has occurred in the antenna angle due to having opened and closed the door of the vehicle  101  by the worker at the time of angle adjustment of the antenna  114 .  FIG. 16  is an explanatory diagram showing a state where an adjustment time error occurs at the time of antenna angle adjustment. For example,  FIG. 16  is a graph showing that an adjustment error occurs in the antenna angle due to contact with a vehicle, such as getting on and off the vehicle by a worker, at the time of angle adjustment of the antenna  114 . In each of the graphs, the vertical axis indicates an angle and the horizontal axis indicates a time. 
     In the processing of performing angle adjustment of the antenna  114 , an antenna angle θa before adjustment which is a current angle of the antenna  114  is detected by the antenna angle detecting section  126 . Then, a target angle θb is read from the ROM  116   b  of the control section  116  and is set as an antenna estimation angle, which is an adjustment estimation value for every predetermined time that changes from the antenna angle θa before adjustment to the target angle θb, as shown in  FIG. 15 . The antenna estimation angle is a criterion for determining whether or not planned adjustment to the target angle is performed. Moreover, as shown in  FIG. 15 , an allowable error range, which is the range of an error that can be allowed from the antenna estimation angle, is set so that the angle adjustment of the antenna  114  is stopped or the user is notified by alarm when the allowable error range is exceeded. 
     In addition, the allowable error range which is the range of an error that can be allowed is also set for the adjustment completion estimation time of estimation time at which the adjustment from the antenna angle θa before adjustment to the target angle θb is completed, as shown in  FIG. 16 . In addition, the CPU  116   a  of the control section  116  calculates the adjustment completion estimation time on the basis of the information regarding the adjustment angle of the antenna and the adjustment speed of the antenna angle. The adjustment completion estimation time is also a criterion for determining whether or not planned adjustment to the target angle is performed so that the angle adjustment of the antenna  114  is stopped or the user is notified by alarm when the allowable error range is exceeded. 
     The following explanation will be given by setting the antenna estimation angle as the adjustment estimation value in  FIG. 15  and the adjustment completion estimation time as the adjustment estimation value in  FIG. 16 . In  FIG. 15 , adjustment starts from the antenna angle θa before adjustment, and an error between the antenna estimation angle and an antenna angle θc of the measurement value that the antenna angle detecting section  126  detects every predetermined time (for example, every 10 msec) is calculated. Specifically, there is no error between the antenna angle θc and the antenna estimation angle from time t 1  to t 3  of the graph, and an error which exceeds the allowable error range is detected at time t 4 . Therefore, at the point of time when the error exceeding the allowable error range has occurred, the angle adjustment is stopped or an alarm indicating that an error has occurred in the adjustment to the target angle of the antenna  114  is generated. As a result, since a malfunction of the radar device  102  can be prevented in advance, safe vehicle control can be provided for the user who uses the vehicle  101 . For example, in the case where antenna angle adjustment is performed at a vehicle factory, a dealer, or the like, it is possible to prevent erroneous angle adjustment occurring when vibration, which is caused by opening and closing of the vehicle door by a worker at the time of antenna angle adjustment after attaching a radar device to the vehicle, is given to the vehicle. 
     In addition, the adjustment work may not be stopped or an alarm may not be generated just because the allowable error range is exceeded by onetime detection, but antenna adjustment may be stopped or an alarm may be generated by determining that an error has occurred in adjustment to the target angle of the antenna  114  when the antenna angle detecting section  126  detects the antenna angle θc at a timing corresponding to each of the plurality of points of time t 1  to t 6  and an error between the angle transition estimation value and the angle detected at each point of time is equal to or larger than a predetermined value and the error is calculated a plural number of times. For example, since the number of detections, in which the error exceeds the allowable error range, among six detections from time t 1  to t 6  is calculated as a plural number of times of t 4  and t 6  in  FIG. 15 , an alarm is generated or the angle adjustment is stopped. 
     In  FIG. 16 , adjustment starts from the antenna angle θa before adjustment, and an adjustment completion estimation time ty until it becomes the target angle θb is calculated beforehand. Moreover, it is assumed that adjustment to the target angle θb has been completed if an adjustment completion time tx when the antenna angle θa before adjustment becomes the target angle θb is equal to the adjustment completion estimation time ty or is in the allowable error range. 
     Moreover, in the present embodiment, if the adjustment completion time tx is not equal to the adjustment completion estimation time ty and is not in the allowable error range, an alarm is generated or the adjustment work is stopped since an error has occurred in the adjustment to the target angle of the antenna  114 . As a result, since a malfunction of the radar device  102  can be prevented in advance, safe vehicle control can be provided for the user who uses the vehicle  101 . For example, in the case where antenna angle adjustment is performed at a vehicle factory, a dealer, or the like, it is possible to prevent erroneous angle adjustment occurring when vibration caused by contact with a vehicle, such as getting on and off the vehicle by a worker, at the time of antenna angle adjustment after attaching a radar device to the vehicle, is given to the vehicle. 
     3. Operation of First Antenna Angle Adjustment 
     Next, an operation of error detection in the first antenna angle adjustment will be described with reference to the processing flow chart in  FIG. 17 . When performing error detection in antenna angle adjustment, the test terminal  140  is connected to the vehicle control device  130  and a power supply of the radar device  102  is turned on to start the adjustment operation (step S 101 ). 
     As the information required to perform the adjustment, the target angle θb of the antenna  114  that makes a beam axis direction, in which the reflection intensity equal to or larger than a fixed value can be obtained from an object, is read from the ROM  116   b  (step S 102 ). 
     Then, the antenna angle θa before adjustment is measured by the antenna angle detecting section  126  (step S 103 ), and the antenna estimation angle which estimates a change from the antenna angle θa before adjustment to the target angle θb is calculated as an adjustment estimation value (step S 104 ). In addition, an allowable error range of a predetermined angle range is set according to the calculation result of the antenna estimation angle. 
     Then, the adjustment completion estimation time ty, which is a time taken for the adjustment from the antenna angle θa before adjustment to the target angle θb, is calculated (step S 105 ). Then, angle adjustment of the antenna  114  from the antenna angle θa before adjustment to the target angle θb is started (step S 106 ). Then, counting of the adjustment time is started simultaneously with the start of the adjustment (step S 107 ), and the angle θc of the antenna under adjustment at each time is measured to detect the measurement value according to the angle variation of the antenna (step S 108 ). 
     The antenna angle θc at each time is compared with an estimated angle θx at each time. If the antenna angle θc is equal to the estimated angle θx or is in the allowable error range (Yes in step S 109 ), it is determined whether or not the antenna angle θc at each time is equal to the target angle θb or is in the allowable error range (step S 110 ). 
     In addition, after comparing the antenna angle θc at each time with the estimated angle θx at each time, if the antenna angle θc is not equal to the estimated angle θx and is not in the allowable error range (No in step S 109 ), an alarm is output to the worker in a vehicle factory, a dealer, or the like (step S 112 ) and then the antenna angle adjustment is stopped (step S 113 ). 
     If the antenna angle θc at each time is not within the range of the target angle θb (No in step S 110 ) in the processing of step S 110 , the counting of the adjustment time is continuously executed (step S 107 ) and the processing of measuring the antenna angle θc at each time (step S 108 ) is continued. In addition, if the antenna angle θc at each time is equal to the target angle θb or is in the error detection range (Yes in step S 110 ), the adjustment of the antenna  114  is ended and it is determined whether or not the adjustment completion estimation time ty estimated beforehand is equal to the adjustment completion time tx or is in the allowable error range (step S 111 ). 
     Then, if the adjustment completion estimation time ty is equal to the adjustment completion time tx or is in the allowable error range (Yes in step S 111 ), the antenna angle adjustment is stopped (step S 113 ). In addition, if the adjustment completion estimation time ty is not equal to the adjustment completion time tx and is not in the allowable error range (No in step S 111 ), an alarm is output to the worker in the vehicle factory, the dealer, or the like (step  5112 ) and then the antenna angle adjustment is stopped (step S 113 ). 
     Thus, by performing angle adjustment of an antenna while detecting the error between the adjustment estimation value of the antenna angle and the measurement value according to the angle variation of the antenna, it is possible to prevent erroneous angle adjustment caused by the factors occurring during the angle adjustment. As a result, accurate angle adjustment to the target angle can be performed. For example, in the case where antenna angle adjustment is performed in a vehicle factory, a dealer, or the like, it is possible to prevent erroneous angle adjustment occurring when vibration caused by contact with a vehicle, such as opening and closing of a vehicle door or getting on and off the vehicle by a worker, at the time of antenna angle adjustment after attaching a radar device to the vehicle, is given to the vehicle. In addition, since a malfunction of the radar device can be prevented in advance, safe vehicle control can be provided for the user who uses the vehicle  101 . 
     In the first antenna angle adjustment processing described until now, processing of performing the error detection in any cases of the state, in which the angle error occurs at the time of antenna angle adjustment as shown in  FIG. 15 , and the state, in which the adjustment time error occurs at the time of antenna angle adjustment as shown in  FIG. 16 , has been described. Apart from this, it is possible to detect an error when an angle error occurs in the midst of antenna angle adjustment, or it is possible to detect an error when an adjustment time error occurs in the midst of antenna angle adjustment. These processing options will be described below as second antenna angle adjustment processing and third antenna angle adjustment processing. 
     4. Operation of Second Antenna Angle Adjustment 
     The second antenna angle adjustment shown in  FIG. 18  is to detect an error when an angle error occurs at the time of antenna angle adjustment. When performing error detection in antenna angle adjustment, the test terminal  140  is connected to the vehicle control device  130  and a power supply of the radar device  102  is turned on to start the adjustment operation (step S 201 ). 
     As the information required to perform the adjustment, the target angle θb of the antenna  114  that makes a beam axis direction, in which the reflection intensity equal to or larger than a fixed value can be obtained from an object, is read from the ROM  116   b  (step S 202 ). 
     Then, the antenna angle θa before adjustment is measured by the antenna angle detecting section  126  (step S 203 ), and the antenna estimation angle which estimates a change from the antenna angle θa before adjustment to the target angle θb is calculated as an adjustment estimation value (step S 204 ). In addition, an allowable error range of a predetermined angle range is set according to the calculation result of the antenna estimation angle. 
     Then, angle adjustment of the antenna  114  from the antenna angle θa before adjustment to the target angle θb is started (step S 205 ). Then, the angle θc of the antenna  114  under adjustment at each time is measured (step S 206 ). 
     The antenna angle θc at each time is compared with the estimated angle θx at each time. If the antenna angle θc of the antenna under adjustment is equal to the estimated angle θx or is in the allowable error range (Yes in step S 207 ), it is determined whether or not the antenna angle θc at each time is equal to the target angle θb or is in the allowable error range (step S 208 ). 
     In addition, after comparing the antenna angle θc at each time with the estimated angle θx at each time, if the antenna angle θc is not equal to the estimated angle θx and is not in the allowable error range (No in step S 207 ), an alarm is output to the worker in a vehicle factory, a dealer, or the like (step S 209 ) and then the antenna angle adjustment is stopped (step S 210 ). 
     If the antenna angle θc at each time is not within the range of the target angle θb (No in step S 208 ) in processing of step S 208 , the processing of measuring the antenna angle θc at each time (step S 206 ) is continued. In addition, if the antenna angle θc at each time is equal to the target angle θb or is in the allowable error range (Yes in step S 208 ), the angle adjustment of the antenna  114  is stopped (step S 210 ). 
     Thus, by performing angle adjustment of an antenna while detecting the error between the estimated angle of the antenna and the antenna angle, it is possible to finely check the antenna angle for every time during the angle adjustment. As a result, since it is possible to prevent erroneous angle adjustment caused by the factors occurring during the angle adjustment, accurate angle adjustment to the target angle can be performed. For example, in the case where antenna angle adjustment is performed at a vehicle factory, a dealer, or the like, it is possible to prevent erroneous angle adjustment occurring when vibration, which is caused by opening and closing of the vehicle door by a worker at the time of antenna angle adjustment after attaching a radar device to the vehicle, is given to the vehicle. 
     5. Operation of Third Antenna Angle Adjustment 
     The third antenna angle adjustment shown in  FIG. 19  is to detect an error when a time error occurs at the time of antenna angle adjustment. The test terminal  140  is connected to the vehicle control device  130  and a power supply of the radar device  102  is turned on to start the adjustment operation (step S 301 ). 
     As the information required to perform the adjustment, the target angle θb of the antenna  114  that makes a beam axis direction, in which the reflection intensity equal to or larger than a fixed value can be obtained from an object, is read from the ROM  116   b  (step S 302 ). 
     Then, the antenna angle θa before adjustment is measured by the antenna angle detecting section  126  (step S 303 ), and the antenna estimation angle which estimates a change from the antenna angle θa before adjustment to the target angle θb is calculated as an adjustment estimation value (step S 304 ). In addition, an allowable error range of a predetermined angle range is set according to the calculation result of the antenna estimation angle. 
     Then, the adjustment completion estimation time ty, which is a time taken for the adjustment from the antenna angle θa before adjustment to the target angle θb, is calculated (step S 305 ). Then, angle adjustment of the antenna  114  from the antenna angle θa before adjustment to the target angle θb is started (step S 306 ). Then, counting of the adjustment time is started simultaneously with the start of the adjustment (step S 307 ), and the angle θc at each time is measured to detect the measurement value according to the angle variation of the antenna (step S 308 ). 
     Then, it is determined whether or not the angle θc at each time is equal to the target angle θb or is in the allowable error range (step S 309 ). If the antenna angle θc at each time is not within the range of the target angle θb (No in step S 309 ) in the processing, the counting of the adjustment time is continuously executed (step S 307 ) and the processing of measuring the antenna angle θc under adjustment (step S 308 ) is continued. In addition, if the antenna angle θc at each time is equal to the target angle θb or is in the error detection range (Yes in step S 309 ), the adjustment of the antenna  114  is ended and it is determined whether or not the adjustment completion estimation time ty estimated beforehand is equal to the adjustment completion time tx or is in the allowable error range (step S 310 ). 
     If the adjustment completion estimation time ty is equal to the adjustment completion time tx or is in the allowable error range (Yes in step S 310 ), the antenna angle adjustment is stopped (step S 312 ). In addition, if the adjustment completion estimation time ty is not equal to the adjustment completion time tx and is not in the allowable error range (No in step S 310 ), an alarm is output to the worker in the vehicle factory, the dealer, or the like (step S 311 ) and then the antenna angle adjustment is stopped (step S 312 ). 
     Thus, by detecting the error between the time from the start of antenna angle adjustment to the completion and the adjustment completion estimation time, it is possible to prevent erroneous angle adjustment caused by the adjustment time difference. As a result, accurate angle adjustment to the target angle can be performed. For example, in the case where antenna angle adjustment is performed at a vehicle factory, a dealer, or the like, it is possible to prevent erroneous angle adjustment occurring when vibration caused by contact with a vehicle, such as getting on and off the vehicle by a worker, at the time of antenna angle adjustment after attaching a radar device to the vehicle, is given to the vehicle.