Patent Publication Number: US-2019187259-A1

Title: Measuring device, control device, control method, and program

Description:
TECHNICAL FIELD 
     The present invention relates to a measurement device, a control device, a control method, and a program. 
     BACKGROUND ART 
     A technology for detecting obstacles and the like by scanning the obstacles by emitting an electromagnetic wave have been developed. Patent Document 1 discloses a technology for detecting an obstacle or the like in which a device installed in an automobile or the like performs a scan within a target area by irradiating a laser beam. In addition, Patent Document 1 discloses a technology for changing a central axis in the horizontal direction of the scan area according to a steering angle of an automobile. 
     RELATED DOCUMENT 
     Patent Document 
     [Patent Document 1] Japanese Patent Application Publication No. 2006-258604 
     SUMMARY OF THE INVENTION 
     Technical Problem 
     In a measuring device that performs a scan using electromagnetic waves, sometimes it is desired to scan an object a desired distance away from the measuring device. A method of enabling the scan of the object positioned at a desired distance away from the measuring device includes a method of appropriately setting a scan range by calibrating the measuring device before operating the measuring device. However, even if the calibration is performed, sometimes it is not possible to scan the object positioned at a desired distance away from the measuring device due to an inaccurate calibration or a change in the posture of the measuring device after the calibration. 
     As the technology disclosed in Patent Document 1, even if the center axis of the scan area is changed in the horizontal direction, a distance between the object to be scanned and the measuring device cannot be the desired distance. 
     The present invention has been made in view of the above-described problems, and one of objects of the present invention is to provide a technology that makes it possible to scan the object a desired distance away with the electromagnetic wave. 
     Solution to Problem 
     The invention according to claim  1  provides (1) a measuring unit that performs a scan by emitting an electromagnetic wave and receiving the electromagnetic wave reflected by a reflection object and (2) a control unit that controls the measuring unit. The control unit determines a scan range in a second scan to be performed after a first scan based on a received signal of the measuring unit at the first scan by the measuring unit. 
     The invention according to claim  8  provides a control device that includes a control unit of the measuring device according to any one of claims  1  to  7 . 
     The invention according to claim  9  provides a control method for controlling a measuring device using a computer. The measuring device is caused to perform a scan by emitting an electromagnetic wave and receiving the electromagnetic wave reflected by a reflection object. In the control method, a scan range in a second scan to be performed after a first scan is determined based on a received signal of the measuring device in the first scan by the measuring device. 
     The invention according to claim  10  provides a program that causes a computer to execute the control method according to claim  9 . 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The object described above and other objects, features and advantages will become more apparent from the following description of the preferred embodiments and the accompanying drawings. 
         FIG. 1  is a block diagram illustrating a measuring device according to an embodiment 1. 
         FIG. 2  is a diagram illustrating a scan range of the measuring unit when seen in a front view. 
         FIG. 3  is a diagram illustrating an electromagnetic wave whose emission directions are different from each other in a height direction. 
         FIG. 4  is a diagram illustrating a scan range determined by a control unit. 
         FIG. 5  is a flowchart illustrating a processing flow executed by the measuring device according to the embodiment 1. 
         FIG. 6  is a diagram illustrating a hardware configuration of the control unit. 
         FIG. 7  is a diagram illustrating a hardware configuration of the measuring unit. 
         FIG. 8  is a diagram illustrating a hardware configuration of the measuring unit that emits light. 
         FIG. 9  is a diagram illustrating a measuring device installed in a moving object. 
         FIG. 10  is a diagram illustrating a trajectory of scan by the measuring unit when seen in a front view. 
         FIG. 11  is a diagram illustrating the scan range seen in a front view that is segmented by a unit of emitting the electromagnetic waves from a measuring device. 
         FIG. 12  is a diagram illustrating a scan range of the measuring unit in a height direction. 
         FIG. 13  is a diagram illustrating a result of scan by the measuring unit. 
         FIG. 14  is a diagram illustrating a result of scan by the measuring unit. 
         FIG. 15  is a diagram illustrating a result of measurement when there is a large obstacle at a position a predetermined distance away from the measuring device. 
         FIG. 16  is a flowchart illustrating a processing flow executed by the control unit according to an embodiment 4. 
         FIG. 17  is a diagram illustrating condition information in a table format. 
         FIG. 18  is a flowchart illustrating a processing flow executed by the control unit according to an embodiment 5. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, similar configuration elements are denoted by the same reference numerals, and the description thereof will not be repeated. 
       FIG. 1  is a block diagram illustrating a measuring device  200  according to an embodiment 1. In  FIG. 1 , each block represents not a configuration in a hardware unit but a configuration in a functional unit. The hardware configuration of the measuring device  200  will be described later with reference to  FIG. 6  to  FIG. 8 . 
     The measuring device  200  includes a measuring unit  202  and a control unit  204 . The measuring unit  202  scans the object by emitting an electromagnetic wave. Here, the measuring unit  202  scans the object while changing the emission direction of the electromagnetic wave in two dimensions of height direction and lateral direction. The height direction means substantially the height direction. In addition, the lateral direction means substantially the horizontal direction. 
       FIG. 2  is a diagram illustrating a scan range of the measuring unit  202  when seen in a front view. A scan range  224  represents the scan range of the measuring unit  202 . 
     The control unit  204  controls the measuring unit  202 . Specifically, the control unit  204  determines the scan range of the subsequent scan performed by the measuring unit  202  in terms of the height direction, based on the received signal of the measuring unit  202  (a signal representing the result of receiving the electromagnetic wave reflected from the object). 
     For example, in the scan performed by the measuring unit  202 , the control unit  204  determines an emission direction that satisfies a predetermined condition of the emission direction from the measuring unit  202  in terms of the height direction, based on an elapsed time from when the measuring unit  202  emits the electromagnetic wave to when the reflected wave of the electromagnetic wave is received by the measuring unit  202 . The predetermined condition is a condition that represents a fact that “an object positioned around a desired distance away from the measuring device  200  has been scanned”. Specific examples of the predetermined condition will be described in the embodiments described later. 
     Here, the distance to the object scanned by the measuring device  200  depends on the height direction of the emitted electromagnetic wave.  FIG. 3  is a diagram illustrating the electromagnetic wave whose emission directions are different from each other in the height direction. In a case of  FIG. 3( a ) , an object located at a distance closer to the measuring device  200  is scanned compared to a case of  FIG. 3( b ) . 
     The control unit  204  determines the scan range in the subsequent scan by the measuring unit  202  in the height direction based on the height direction of the emission direction that satisfies the predetermined condition. For example, the control unit  204  determines a new scan range  224  such that the height direction of the emission direction satisfying the predetermined condition becomes a center of the scan range  224  in the height direction. The subsequent scan by the measuring unit  202  is performed on the scan range determined in this way. 
       FIG. 4  is a diagram illustrating the scan range  224  determined by the control unit  204 .  FIG. 4( a )  represents a scan range  224 - 1  before the determination is performed by the control unit  204 . On the other hand,  FIG. 4( b )  represents a scan range  224 - 2  newly determined by the control unit  204 . A cross mark in  FIG. 4  represents the direction toward which the electromagnetic wave satisfying the predetermined condition is emitted. In the example in  FIG. 4 , the control unit  204  determines the new scan range  224 - 2  such that the height direction of the cross mark in the emission direction becomes a predetermined position in the height direction of the scan range. For example, in  FIG. 4( b ) , the control unit  204  determines the new scan range  224 - 2  such that the height direction of the cross mark in the emission direction becomes a center in the height direction of the scan range. 
     As illustrated in  FIG. 3 , the distance to the object scanned by the measuring device  200  depends on the height direction of the emitted electromagnetic wave (refer to  FIG. 3 ). According to the measuring device  200  in the present embodiment, the scan range  224  of the subsequent scan performed by the measuring unit  202  is determined based on the result of scan performed by the measuring unit  202 . More specifically, the scan range  224  is determined in terms of the height direction such that the direction toward the desired distance away from the measuring device  200  becomes a predetermined position (for example, the center) in the height direction of the scan range  224 . Therefore, an object positioned at a desired distance away from the measuring device  200  can be scanned by the measuring device  200 . 
     The measuring device  200  is installed in a moving object such as an automobile or a train. The measuring device  200  is used, for example, for detecting an obstacle on the flow line of such a moving object. In this case, it may be preferable to be able to detect the obstacle positioned at a desired distance away from the moving object. 
     As a method of enabling the scan of an object positioned around a desired distance away from the measuring device  200 , it is conceivable to calibrate the measuring device  200  before operating the measuring device  200 . However, it is sometimes not possible to scan the object positioned around a desired distance away even if the calibration is performed, since the calibration may be inaccurate, or the pose of the measuring device  200  may change due to vibration applied to the measuring device  200  during the operation. 
     According to the measuring device  200  in the present embodiment, the scan range  224  is automatically adjusted in terms of the height direction during the operation of the measuring device  200 . Therefore, even when the calibration is inaccurate, or the pose of the measuring device  200  changes due to vibration applied to the measuring device  200  during the operation, it is possible to automatically perform the adjustment such that the measuring device  200  can scan the object positioned around the desired distance away from the measuring device  200 . 
     Furthermore, according to the measuring device  200  in the present embodiment, even if the calibration of the measuring device  200  is not performed, it is possible to automatically adjust the scan range of the measuring device  200  so as to can scan the object positioned around the desired distance away from the measuring device  200 . Therefore, it is possible to omit the effort for calibrating the measuring device  200 . 
     Hereinafter, the measuring device  200  in the present embodiment will be described in detail. 
     &lt;Processing Flow&gt; 
       FIG. 5  is a flowchart illustrating a processing flow executed by the measuring device  200  according to the embodiment 1. The measuring unit  202  emits the electromagnetic wave and performs the scan of the object (S 102 ). The control unit  204  determines the scan range of the subsequent scan performed by the measuring unit  202  based on the received signal of measuring unit  202  due to the scan performed in S 102  (S 104 ). 
     &lt;Hardware Configuration Example of Measuring Device  200 &gt; 
     Each functional configuration unit of the measuring device  200  may be realized by hardware (for example, hard-wired electronic circuit, or the like) that realizes each functional configuration unit, or may be realized by a combination of hardware and software (for example, a combination of an electronic circuit and a program for controlling the circuit). Hereinafter, the case where each functional configuration unit of the measuring device  200  is realized by a combination of the hardware and the software will be further described. 
       FIG. 6  is a diagram illustrating a hardware configuration of the control unit  204 . An integrated circuit  100  is an integrated circuit realizing the control unit  204 . For example, the integrated circuit  100  is a SoC (System On Chip). 
     The integrated circuit  100  includes a bus  102 , a processor  104 , a memory  106 , a storage device  108 , an input/output interface  110 , and a network interface  112 . The bus  102  is a data transmission path through which the processor  104 , the memory  106 , the storage device  108 , the input/output interface  110 , and the network interface  112  mutually transmit and receive data. However, the method of connecting the processor  104  and the like to each other is not limited to the bus connection. The processor  104  is a processor realized by using a microprocessor or the like. The memory  106  is a memory realized by using RAM (Random Access Memory) or the like. The storage device  108  is a storage device realized by using ROM (Read Only Memory), a flash memory, or the like. 
     The input/output interface  110  is an interface for connecting the integrated circuit  100  to peripheral devices. In  FIG. 6 , an emitter driver circuit  30  is connected to the input/output interface  110 . The emitter driver circuit  30  will be described later. 
     The network interface  112  is an interface for connecting the integrated circuit  100  to a communication network. The communication network is, for example, a controller area network (CAN) communication network. The method for the network interface  112  to connect to the communication network may be a wireless connection or may be a wired connection. 
     The storage device  108  stores a program module for realizing the function of the control unit  204 . The processor  104  realizes the function of the control unit  204  by reading the program module out to the memory  106  and executing the program module. 
     The hardware configuration of the integrated circuit  100  is not limited to the configuration illustrated in  FIG. 6 . For example, the program module may be stored in the memory  106 . In this case, the integrated circuit  100  may not include the storage device  108 . 
     &lt;&lt;Hardware Configuration Example of Measuring Unit  202 &gt;&gt; 
       FIG. 7  is a diagram illustrating a hardware configuration of the measuring unit  202 . The measuring unit  202  includes an emitter  10 , an emitter driver circuit  30 , and a receiver  50 . The emitter  10  emits the electromagnetic wave used for the scan. Here, the emitter  10  is configured to be variable in terms of the emission direction, and is therefore possible to emit the electromagnetic wave in various directions. The emitter driver circuit  30  is a circuit for driving the emitter  10 . The receiver  50  receives a reflected wave of the electromagnetic wave emitted to the outside of the measuring device  200 . 
     The control unit  204  detects that the reflected wave is received by the receiver  50 . For example, the receiver  50  is configured to transmit a predetermined signal to the control unit  204  in response to the reception of the reflected wave. The control unit  204  detects that the reflected wave is received by the receiver  50  by receiving the predetermined signal. The received signal of the measuring unit  202  is, for example, the predetermined signal. 
     The electromagnetic wave emitted by the emitter  10  may be a light beam such as a laser beam or a radio wave such as Extremely high frequency wave. Hereinafter, the hardware configuration of the measuring unit  202  when the emitter  10  emits light will be described. The same configuration can be adopted for the measuring unit  202  when the emitter  10  emits the electromagnetic wave. 
       FIG. 8  is a diagram illustrating a hardware configuration of the measuring unit  202  that emits light. A light projector  12  and a light projector driver circuit  32  in  FIG. 8  are examples of the emitter  10  and the emitter driver circuit  30  in  FIG. 7 , respectively. The light projector  12  includes a light source  14  and a movable reflector  16 . The light projector driver circuit  32  includes a light source driver circuit  34  and a movable reflector driver circuit  36 . 
     The light source  14  is any light source that emits the light. The light source driver circuit  34  is a circuit that drives the light source  14  by controlling the supply of power to the light source  14 . The light emitted by the light source  14  is, for example, a laser beam. In this case, for example, the light source  14  is a semiconductor laser that emits the laser beam. 
     The movable reflector  16  reflects the light emitted from the light source  14 . The light reflected by the movable reflector  16  is emitted to the outside of the measuring device  200 . The movable reflector driver circuit  36  is a circuit for driving the movable reflector  16 . For example, the movable reflector  16  includes one mirror that is configured to be rotatable at least in two directions: the height direction and the lateral direction. This mirror is, for example, a micro electro mechanical system (MEMS) mirror. 
     The configuration of the movable reflector  16  is not limited to the configuration illustrated in  FIG. 8 . For example, the movable reflector  16  may include two mirrors whose axes of rotation intersect each other. 
     Furthermore in  FIG. 8 , the measuring unit  202  includes a light receiver  52 . The light receiver  52  is an example of the receiver  50  in  FIG. 7 . The light receiver  52  receives the reflected light of the light emitted to the outside of the measuring device  200 . For example, the light receiver  52  includes an avalanche photodiode (APD). 
     The configuration of the measuring unit  202  is not limited to the configurations illustrated in  FIG. 7  and  FIG. 8 . For example, in  FIG. 8 , the measuring unit  202  is configured to be able to emit the light in various directions by reflecting the light emitted from the light source  14  by the movable reflector  16 . However, the configuration for emitting the light in various directions is not limited to the configuration illustrated in  FIG. 8 . For example, the light source  14  itself may include a mechanism of rotating in the height direction and the lateral direction. In this case, the measuring unit  202  can emit the light in various directions by controlling the pose of the light source  14 . In addition in this case, the measuring unit  202  may not include the movable reflector  16  and the movable reflector driver circuit  36 . Furthermore in this case, the light source driver circuit  34  controls the pose of the light source  14  in addition to the light emission by the light source  14 . 
     The hardware for realizing the control unit  204  (refer to  FIG. 6 ) and the hardware for realizing the measuring unit  202  (refer to  FIG. 7  and  FIG. 8 ) may be packaged in the same housing or may be packaged in the separated housings. 
     &lt;Installation Example of Measuring Device  200 &gt; 
     The measuring device  200  is installed in a moving object such as an automobile or a train.  FIG. 9  is a diagram illustrating the measuring device  200  installed in a moving object  240 . In  FIG. 9 , the measuring device  200  is fixed on the top portion of the moving object  240 . In addition, the measuring device  200  is connected to the control device  244  through the CAN communication network  242 . The control device  244  is a control device that controls the moving object  240 . For example, the control device  244  is an electronic control unit (ECU). 
     Here, the control unit  204  may be realized as a part of the control device  244  that controls the moving object  240 . In this case, the program module for realizing the above-described control unit  204  is stored in the storage device included in the control device  244 . 
     The place where the measuring device  200  is installed is not limited to the top portion of the moving object  240 . For example, the measuring device  200  may be installed inside (for example, in a cabin) the moving object  240 . The measuring device  200  may also be installed on a non-moving object. 
     &lt;Scan by Measuring Unit  202 &gt; 
     The scan by the measuring unit  202  may be the scan performed in the lateral direction or may be the scan performed in the height direction.  FIG. 10  is a diagram illustrating a trajectory of scan by the measuring unit  202  when seen in a front view.  FIG. 10( a )  illustrates the scan performed in the lateral direction. In  FIG. 10( a ) , the scan in the lateral direction are sequentially performed for n lines (n is a natural number) whose height directions of the emission of the electromagnetic waves are different from each other. Specifically, a scan  220 - 1  to a scan  220 - n  are sequentially performed. Then, after the scan  220 - n  is performed, the scan  220 - 1  to the scan  220 - n  are sequentially performed again. 
     Hereinafter, it is represented as “line scan” to perform scan in a single line. In addition, it is collectively represented as “perform one cycle of scan” to perform the scan once for each of the n lines (for example, the scan  220 - 1  to the scan  220 - n  are performed once in  FIG. 10( a ) ). 
       FIG. 10( b )  illustrates the scan performed in the height direction. In terms of the scan in the height direction, the scan in the height direction is sequentially performed for n lines whose lateral directions of the emission of the electromagnetic waves are different from each other. Also in terms of the scan in the height direction, it is collectively represented as “perform one cycle of scan” to perform scan once for each of the n lines (for example, the scan  222 - 1  to the scan  222 - n  are performed once in  FIG. 10( b ) ). 
     The scan range of the measuring unit  202  represents a range scanned in one cycle of scan. In other words, the scan range of the measuring unit  202  is determined by a swing width of the electromagnetic wave emitted by the measuring device  200  in the height direction and a swing width in the lateral direction. 
     The measuring unit  202  emits the electromagnetic waves in a plurality of directions in one line scan by emitting the electromagnetic waves a plurality of times in one line scan.  FIG. 11  is a diagram illustrating the scan range  224  seen in a front view that is segmented by a unit of emitting the electromagnetic waves from the measuring device  200 . The measuring unit  202  emits each electromagnetic wave so as to pass through each grid illustrated in  FIG. 11 . For each emitted electromagnetic wave, the measuring device  200  measures time from the emission of the electromagnetic wave to the reception of the reflected wave by the measuring device  200 . Hereinafter, the directions of the electromagnetic waves emitted so as to pass through the i th  row and the j th  column (both i and j are positive integers) of the scan range  224  segmented in the grid shape is defined as “direction to i th  row and j th  column”. 
     &lt;Measurement by Measuring Device  200 &gt; 
     The control unit  204  measures an elapsed time from the emission of the electromagnetic wave from the emitter  10  to the reception of the reflected wave of the electromagnetic wave by the receiver  50 , and then stores the measured time in a storage device (for example, the storage device  108 ) in association with the emission direction. This elapsed time is, for example, represented by a value obtained by multiplying the number of clock signals, which is counted during the period from the emission of the electromagnetic wave from the emitter  10  to the reception of the reflected wave of the electromagnetic wave, by the clock frequency. In addition, for example, this elapsed time may be represented by the number of clock signals counted. 
     Embodiment 2 
     Similarly to the measuring device  200  in the embodiment 1, a measuring device  200  in an embodiment 2 is represented by, for example,  FIG. 1 . The function of the measuring device  200  in the embodiment 2 is the same as the function of the measuring device  200  in the embodiment 1 except for the points described below. 
     In the present embodiment, the measuring unit  202  performs a line scan in the lateral direction (refer to  FIG. 10( a ) ). The control unit  204  determines the scan range of the measuring unit  202  by determining the center of the scan range in the height direction (the center direction of the swing width in the height direction toward which the measuring device  200  emits the electromagnetic wave), regarding the measuring unit  202  performing such the line scan in lateral direction. 
       FIG. 12  is a diagram illustrating the scan range of the measuring unit  202  in the height direction. An upper-most direction  225  is a direction passing an upper-most position of the scan range  224  in the height direction. A center direction  226  is a direction passing through a center position of the scan range  224  in the height direction. A lowest direction  227  is a direction passing through a lowest position of the scan range  224  in the height direction. 
     In  FIG. 12( a ) , the angle formed by the center direction  226  and the Y axis is θ 1 . In addition, the swing width of the emission direction of the electromagnetic wave from the measuring device  200  is 2α. Therefore, the direction toward which the measuring device  200  emits the electromagnetic waves is in the range of θ 1 −α to θ 1 +α in terms of the height direction. 
     Here in the example in  FIG. 12 , it is assumed that the control unit  204  in the present embodiment determines to set the center direction of the scan range  224  in the height direction to θ 2 . Then, the scan range in the height direction of the subsequent scan is the range illustrated in  FIG. 12( b ) . Specifically, the direction toward which the measuring device  200  emits the electromagnetic wave becomes in the range of θ 2 −α to θ 2 +α in terms of the height direction. 
     The control unit  204  performs the determination of the scan range  224  based on results of a plurality of line scans among a plurality of line scans (for example, the scan  220 - 1  to the scan  220 - n  in  FIG. 10( b ) ) performed in the lateral direction. Hereinafter, the line scan used for the determination of the scan range  224  is represented as a target line scan. 
     The target line scans may be all the line scans in a certain one cycle or a part of line scans in a certain one cycle. Furthermore, all the target line scans may be included in one cycle, or all or a part of the target line scans may be included in different cycles. Information indicating which line scan is handled as a target line scan may be set in the control unit  204  in advance or may be stored in the storage device to which the control unit  204  can access. 
     The control unit  204  determines a result of measurement that satisfies a predetermined condition from the results of measurement in a plurality of target line scans. As described above, the predetermined condition is a condition representing a fact that “an object positioned around a desired distance away from the measuring device  200  is scanned”. The control unit  204  determines the scan range of the subsequent scan in the cycle after those cycles based on the determined results of measurement. 
     For example, the predetermined condition described above is a condition relating to the distance between the object scanned by the measuring device  200  and the measuring device  200  or a condition relating to the elapsed time measured by the measuring device  200 . Hereinafter, several methods for determining the scan range  224  using the conditions relating to each factor will be exemplified. 
     &lt;Determination Method 1&gt; 
     The control unit  204  performs the determination of the scan range  224  based on the result of measurement in which the distance between each object scanned in the plurality of target line scans and the measuring device  200  satisfies a predetermined condition. In order to do that, the control unit  204  calculates the distance between each object scanned and the measuring device  200  based on the result of measurement in the multiple target line scans. Then, the control unit  204  determines the scan range  224  based on the result of measurement in which the distance satisfies the predetermined condition. 
     To that end, firstly, the control unit  204  computes the distance between each object scanned by the measuring unit  202  and the measuring device  200 . The computation is performed using, for example, the following Equation (1). 
       [Equation 1] 
         D[m][i][j]=C*t[m][i][j]/ 2   (1)
 
     Here, D[m][i][j] represents the distance compute for the electromagnetic waves emitted in the direction to i th  row and j th  column in the m th  cycle. C represents a speed of the electromagnetic wave. t[m][i][j] represents the elapsed time measured for the electromagnetic wave emitted in the direction to i th  row and j th  column in the m th  cycle. However, when the elapsed time is represented by the number of clocks, what used for t[m][i][j] is a value obtained by multiplying the measurement time (the number of clocks) measured for the electromagnetic waves emitted in the direction to the i th  row and j th  column in the m th  cycle by the clock frequency. 
     The control unit  204  sets the predetermined distance or a predetermined range for the distance as the predetermined condition described above. Each of those will be described in detail below. 
     &lt;When Predetermined Distance is Used as Predetermined Condition&gt; 
     The control unit  204  determines a distance closest to the predetermined distance among the distances D[m][i][j] computed for the plurality of target line scans. The predetermined distance may be set in the control unit  204  in advance or may be stored in a storage device to which the control unit  204  can access. 
     Then, the control unit  204  sets the height direction of the emission direction in the scan from which the determined distance is obtained, as the center of the scan range  224  in the height direction at the subsequent scan. For example, suppose that the distance closest to the predetermined distance is D[2][3][4]. In this case, the control unit  204  sets the center of the scan range  224  in the height direction for the subsequent scans, to the height direction of the emission direction at the target line scan of the third row in the second cycle. 
     Here, it is assumed that, the distance closest to the predetermined distance is computed in each of two or more target line scans. The control unit  204  may determine the scan range  224  in the subsequent scan using (1) the height direction of the emission direction in one target line scan among two or more target line scans, or (2) a statistical value of the height directions of the emission direction in those two or more target line scans. 
     In the former case, for example, the control unit  204  counts the number of result of measurements in which the distance closest to the predetermined distance is computed, for each target line scan. Then, the control unit  204  determines the height direction of the emission direction in the target line scan having the largest number, as the center of the scan range  224  in the height direction in the subsequent scan. Note that, the above-described two or more target line scans may include only the line scan in the same cycle, or may include the line scan in different cycles. Hereinafter, details of the method will be described with condition to the drawings. 
       FIG. 13  is a diagram illustrating a result of scan by the measuring unit  202 . In  FIG. 13 , similar to  FIG. 11 , the scan range  224  is segmented in the grid shape. In the example in  FIG. 13 , the predetermined distance is 100 m. Cross marks are indicated in the emission direction corresponding to the electromagnetic wave whose distance from the measuring device  200  to the object is computed as 100 m. 
     In  FIG. 13 , in the distances computed for the target line scans in the fourth line, there are three 100 m points, which are the same as the predetermined distance. On the other hand, in the distance computed for the target line scans in the fifth row, there are six 100 m points, which are the same as the predetermined distance. Therefore, the control unit  204  sets the height direction of the emission direction in the target line scans of the fifth line, as the center of the height direction of the scan range  224  in the subsequent scan. 
     When statistical values of height direction of the emission direction for two or more target line scans are used, the control unit  204  sets the statistical value of the height direction of the emission direction in these target line scan, as the center of the height direction of the scan range  224  in the subsequent scan. For example in the case in  FIG. 13 , the control unit  204  computes an average of the height direction of the emission direction in the target line scan for the fourth row and the height direction of the emission direction in the target line scan for the fifth row, as the center of the height direction of the scan range  224  in the subsequent scan. At this time, the control unit  204  may determine the number of result of measurements for which the distance closest to the predetermined distance is computed for each target line scan, and may calculate a weighted average based on the number. For example in the case in  FIG. 13 , the control unit  204  assigns a weight of 3 to the height direction of the emission direction in the target line scan for the fourth row, assigns a weight of 6 to the height direction of the emission direction in the target line scan for the fifth row, and then, computes the weighted average. 
     When using the result of scan in a plurality of cycles, for example, the control unit  204  may operate as follows. Firstly, the control unit  204  determines a target line scan having the largest number of distances closest to the predetermined distance, for each cycle. The control unit  204  sets the statistical value of the height direction of the emission direction in each determined target line scan, as the center of the height direction of the scan range  224  in the subsequent scan. 
     For example, it is assumed that the scan range in the scan in the subsequent cycle is determined using the result of scans from the first cycle to the fifth cycle. In this case, it is assumed that the target line scans having the largest number of distances closest to the predetermined distance for each cycle are: the target line scan in the fifth line in the first cycle; the target line scan in the fourth line in the second cycle; the target line scan in the fifth line in the third cycle; the target line scan in the sixth line in the fourth cycle; and the target line scan in the fifth line in the fifth cycle. In this case, for example, the control unit  204  determines the height direction of the emission direction in the target line scan for the fifth row, which is the most frequent value, as the center of the height direction of the scan range  224  in the subsequent scan. In another example, the control unit  204  determines the average of the height direction of the emission direction in each determined target line scan, as the center of the height direction of the scan range  224  in the subsequent scan. 
     &lt;&lt;When Predetermined Range of Distance is Set as Predetermined Condition&gt;&gt; 
     The control unit  204  determines the scan range such that the distance to the object scanned by the measuring unit  202  becomes the distance included in the predetermined range. Therefore, the control unit  204  computes the distance D[m][i][j] for each of two or more target line scans using the above-described method. Further, the control unit  204  determines the distance included in the predetermined range from the calculated distance D[m][i][j]. Then, the control unit  204  sets the height direction of the emission direction in the target line scan from which the determined distance is obtained, as the center of the height direction of the scan range  224  in the subsequent scan. The predetermined range may be set in advance in the control unit  204  or may be stored in a storage device to which the control unit  204  can access. 
     Here, it is assumed that the distance included in the predetermined range is computed from the result of measurement for each of two or more target line scan. In this case, the control unit  204  determines the center of the height direction of the scan range  224  in the subsequent scan, based on the result of those two or more target line scans. This method is similar to the case in which, when the predetermined distance is used as the predetermined condition, the center of the height direction of the scan range  224  in the subsequent scan is determined based on the result of two or more target line scans for which the distance closest to the predetermined distance is computed. For example, the control unit  204  sets the height direction of the emission direction in the target line scan having the largest number of results of measurement in which the distance included in the predetermined range is computed, as the center of the height direction of the scan range  224  at the subsequent scan. 
     &lt;Determination Method 2&gt; 
     The control unit  204  performs the determination of the scan range  224  based on the result of measurement in which the elapsed times measured in a plurality of target line scans satisfies a predetermined condition. In this case, a predetermined time or a predetermined range of elapsed time is used as the predetermined condition. Each will be described below. 
     &lt;&lt;When Predetermined Time is Used as Predetermined Condition&gt;&gt; 
     By the same method as in the case where the predetermined distance is used as the predetermined condition in the determination method 1 described above, the control unit  204  performs the determination of the scan range  224  using the predetermined time as the predetermined condition. This predetermined time corresponds to time between when the electromagnetic wave is emitted to the object positioned at the predetermined distance from the measuring device  200  and when the reflected wave of the electromagnetic wave is received by the measuring device  200 . For example, the predetermined time tp can be computed using the predetermined distance dp and the speed C of the electromagnetic wave based on the following Equation (2). The predetermined time tp may be set in advance in the control unit  204  or may be stored in a storage device to which the control unit  204  can access. 
     
       
         
           
             
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   
                     ( 
                     2 
                     ) 
                   
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   tp 
                   = 
                   
                     
                       2 
                       * 
                       dp 
                     
                     C 
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     The control unit  204  performs the determination of the scan range  224  using the predetermined time tp. For example, the control unit  204  specifies the elapsed time closest to the predetermined time tp from the elapsed times t[m][i][j] measured for a plurality of target line scans. Then, the control unit  204  sets the height direction of the emission direction of the electromagnetic wave in the target line scan from which the determined elapsed time is obtained, as the center of the height direction of the scan range  224  in the subsequent scan. In addition, the method of determining the scan range when the elapsed time nearest to the predetermined time tp is measured for a plurality of target line scans is similar to the method of determining the scan range  224  when the distance closest to the predetermined distance is computed for a plurality of target line scans in the determination method 1. 
     &lt;&lt;When Predetermined Range of Elapsed Time is Used as Predetermined Condition&gt;&gt; 
     By the same method as in the case the predetermined range of the distance is used as the predetermined condition in the above determination method 1, the control unit  204  performs the determination of the scan range  224  using the predetermined range of elapsed time as the predetermined condition. The lower limit value of the predetermined range of the elapsed time can be computed based on the lower limit value of the predetermined range of the distance and Equation (2) described above. In addition, the upper limit value of the predetermined range of the elapsed time can be calculated based on the upper limit value of the predetermined range of the distance and Equation (2) described above. The predetermined range may be set in advance in the control unit  204  or may be stored in the storage unit that the control unit  204  can access. 
     For example, the control unit  204  determines the elapsed time included in the predetermined range of elapsed time, from the elapsed times t[m][i][j]. Then, the control unit  204  sets the height direction of the emission direction in the target line scan from which the determined elapsed time is obtained, as the center of the height direction of the scan range  224  in the subsequent scan. The method of determining the scan range when the elapsed time included in the predetermined range is measured for a plurality of target line scans is similar to the method of determining the scan range when the distance included in the predetermined range is computed for a plurality of target line scans in determination method 1. 
     &lt;Timing for Performing Determination of Scan Range  224 &gt; 
     The timing for the control unit  204  to perform the determination of the scan range  224  may be any timing. For example, the control unit  204  periodically performs the determination of the scan range  224 . In this way, it is possible to assure that the center of the height direction of scan range  224  is in the desired direction at a periodic timing. 
     In another example, the control unit  204  may perform the determination of the scan range  224  in response to the detection of vibration. For example, the detection of the vibration is performed using a vibration sensor. The vibration sensor may be provided inside the measuring device  200  or may be provided outside the measuring device  200 . In the latter case, for example, the vibration sensor is provided in the moving object  240 . In this case, if a vibration having a magnitude larger than a predetermined magnitude is detected by the moving object  240 , the measuring device  200  receives notification of the detection from the moving object. Then, the measuring device  200  performs the determination of the scan range  224  in response to the reception of the notification. In this way, the determination of the scan range  224  is performed at a timing at which there is a possibility that the pose of the measuring device  200  may change due to the vibration applied to the moving object  240  on which the measuring device  200  or the measuring device  200  is installed, and thus, the scan range  224  is adjusted. Therefore, even if the pose of the measuring device  200  changes due to the vibration, the center of the scan range  224  in the height direction can be kept in a desired direction. 
     &lt;Example of Hardware Configuration&gt; 
     Similar to the hardware configuration of the measuring device  200  in the embodiment 1, the hardware configuration of the measuring device  200  in the embodiment 2 is illustrated, for example, in  FIG. 6  to  FIG. 8 . In addition, in the present embodiment, a program for realizing the functions described in the present embodiment is further included in the program module stored in the storage device  108  described above. 
     According to the measuring device  200  in the present embodiment, the center of the scan range  224  in the height direction is determined based on the result of measurement and the predetermined condition in the scan in the lateral direction. In this way, even when the calibration is inaccurate, or the pose of the measuring device  200  is changed due to vibration applied to the measuring device  200  during the operation, it is possible to make the object around a desired distance away from the measuring device  200  be included in the scan range  224 . In addition, it is possible to omit the effort of calibrating the measuring device  200 . 
     Embodiment 3 
     A measuring device  200  in an embodiment 3 is represented by, for example,  FIG. 1 , similarly to the measuring device  200  in the embodiment 1 or in the embodiment 2. The function of the measuring device  200  in the embodiment 3 is the same as the function of the measuring device  200  in the embodiment 1 except the points described below. 
     In the present embodiment, the measuring unit  202  performs a line scan in the height direction (see  FIG. 10( b ) ). The control unit  204  determines the scan range of the measuring unit  202  by determining the center of the scan range  224  in the height direction (the center of the swing width of the emission direction of the emitter  10 ) for the measuring unit  202  performing the line scan in the height direction. 
     Here, the measuring unit  202  in the embodiment 2 performs the determination of the scan range using a plurality of results of line scans as described above. On the contrary, the measuring unit  202  in the present embodiment may perform the determination of the scan range based on a certain one result of line scan, or may perform the determination of the scan range based on a plurality of results of line scans. The reason thereof is as follows. 
     First, the distance between the object scanned by the measuring device  200  and the measuring device  200  depends on the height direction of the emitted electromagnetic wave, while less depending on the lateral direction of the electromagnetic wave. Therefore, in the line scan in the lateral direction, there is a high probability that the distance between each object scanned in the line scan and the measuring device  200  may be substantially the same. Therefore, in only one line scan, it is not highly possible to obtain the result of measurement of scanning the object positioned around a desired distance away from the measuring device  200 . Therefore, the measuring device  200  in the embodiment 2 uses the result of measurement for a plurality of line scans. 
     On the other hand, in the line scan in the height direction, each emission direction of the electromagnetic wave emitted in one line scan differs from each other in the height direction. Therefore, in the line scan in the height direction, there is a high probability that the distances between each object scanned in the line scan and the measuring device  200  are different from each other. Therefore, even in only one line scan, with a high probability, it is possible to obtain the result of measurement of scanning the object around a desired distance away from the measuring device  200 . Therefore, the measuring device  200  in the present embodiment can determine the scan range  224  based on one result of line scan. 
     The control unit  204  performs the determination of the scan range based on one or more results of line scans among a plurality of line scans (for example, the scan  222 - 1  to the scan  222 - n  in  FIG. 10( b ) ) performed in the height direction. As described above, the line scan used for determining the scan range is described as the target line scan. When a plurality of line scans are handled as the target line scan, all the target line scans may be included in one cycle, or all or a part of the target line scans may be included in different cycles. Information indicating which line scan is treated as a target line scan may be set in the control unit  204  in advance or may be stored in the storage device to which the control unit  204  can access. 
     In the present embodiment also, the control unit  204  determines the scan range  224  based on the various predetermined conditions (such as the predetermined distance, the predetermined range of distance, the predetermined time, the predetermined range of the elapsed time, and the like) described in the embodiment 2. Hereafter, details will be described below. 
     &lt;Determination Method 1&gt; 
     The control unit  204  calculates the distance from each object scanned in the target line scan to the measuring device  200 , respectively. Then, the control unit  204  determines the scan range  224  using the predetermined distance or the predetermined range of the distance as the predetermined condition. 
     &lt;&lt;When Predetermined Distance is Used as Predetermined Condition&gt;&gt; 
     The control unit  204  determines the distance closest to the predetermined distance from the plurality of distances D [m][i][j] computed in the target line scan. Then, the control unit  204  determines the height direction of the emission direction of the electromagnetic wave corresponding to the result of measurement for which the predetermined distance is computed as the center of the scan range  224  in the height direction in the subsequent scan. 
     For example, it is assumed that the distance closest to the predetermined distance among the computed distances is D[1][4][5]. In this case, the control unit  204  determines the height direction (the height direction of the fourth row) of the electromagnetic wave emitted in the direction of fourth row and fifth column as the center of the scan range  224  in the height direction in the subsequent scan. The method of computing the distance from the scanned object to the measuring device  200  is the same as that described in the embodiment 1. 
     Here, it is assumed that the distance closest to the predetermined distance is computed for two or more results of measurements. In this case, for example, the control unit  204  sets the statistical value of the height direction of the emission direction of the electromagnetic wave when each result of measurement is obtained, as the center of the scan range  224  in the height direction in the subsequent scan. 
       FIG. 14  is a diagram illustrating a result of scan by the measuring unit  202 . In  FIG. 14 , the scan range  224  segmented in a grid shape is illustrated. In  FIG. 14 , the scan range  224  is segmented in the grid shape as in  FIG. 11 . In the example in  FIG. 14 , the predetermined distance is 100 m. Cross marks are indicated in the grid corresponding to the emission direction of the electromagnetic wave whose distance from the measuring device  200  to the object is 100 m. 
     In  FIG. 14 , the grids where the cross mark is indicated are a grid of fourth row and fifth column and a grid of fifth row and sixth column. Therefore, the control unit  204  sets the statistic value (for example, average) of the height direction of the fourth row and the height direction of the fifth row, as the center of the scan range  224  in the height direction in the subsequent scan. 
     Here, the control unit  204  may exclude a part of target line scans from the calculation target of the statistical value when calculating the statistical value. As described above, the measuring device  200  is installed in the moving object  240 , for example. In this case, for example in the measuring device  200 , it is preferable that the center of the scan range  224  in the height direction is a direction toward the object positioned around the predetermined distance (for example, 100 m) away from the measuring device  200 . 
     At this time, if there is a large obstacle such as a building around the predetermined distance away from the measuring device  200 , in the result of measurement of the line scan which scans the obstacle, many results of measurements that calculate the distances that are the same as or close to the predetermined distance are included.  FIG. 15  is a diagram illustrating a result of measurement when there is a large obstacle around a position a predetermined distance away from the measuring device  200 . In  FIG. 15 , the predetermined distance is 100 m. Then, cross marks are indicated in the result of measurement in which the distance from the measuring device  200  is computed as 100 m. 
     The line scan  222 - 1  is scanning the road. In this case, the distances between each position of the road scanned by the line scan  222 - 1  and the measuring device  200  are different from each other. Therefore, in the line scan  222 - 1 , there is only one result of measurement in which the distance is computed as 100 m which is same as the predetermined distance. Accordingly, if the result of measurement of the line scan  222 - 1  is used, it is possible to appropriately determine the center of the scan range  224  in the height direction. 
     On the other hand, the line scan  222 - 2  is scanning the building  228 . The building  228  is standing at 100 m away from the measuring device  200 . Therefore, in the line scan  222 - 2 , there are many results of measurements in which the distance is calculated as 100 m which is the same as the predetermined distance. Therefore, if the result of measurement of the line scan  222 - 2  is used, there is a problem in that the center of the scan range  224  in the height direction of scan may not be appropriately determined. 
     Therefore, among the target line scans for which the measurement result where the distance closest to the predetermined distance is computed is obtained, the control unit  204  excludes the line scan, in which a lot of computation results where the distance closest to the predetermined distance is computed similar to the line scan  222 - 2  in  FIG. 15 , from targets of computing the above-mentioned statistical value. For example, from the target line scan for which the distance closest to the predetermined distance is computed, the control unit  204  extracts only a target line scan whose number of results of measurements in which that distance is computed is equal to or less than a predetermined number. Then, in this extracted target line scan, the control unit  204  computes a statistical value of the height direction of the emission direction of the electromagnetic wave corresponding to each result of measurement in which the distance closest to the predetermined distance is computed. In this way, even if there is a large obstacle at or near the predetermined distance away from the measuring device  200 , the scan range  224  of the measuring device  200  can appropriately be determined. 
     In addition, according to this method, like the result of measurement in which the large obstacle is scanned, it is possible to exclude the line scan which may cause the decrease of the accuracy of determination of the scan range  224  by the control unit  204  with a simple method. Therefore, the accuracy of determination of the scan range  224  by the control unit  204  can be increased with a simple method. 
     &lt;&lt;When Predetermined Range of Distance is Used as Predetermined Condition&gt;&gt; 
     The control unit  204  determines the scan range such that the distance to the object scanned by the measuring unit  202  becomes the distance included in the predetermined range. The control unit  204  calculates the distance D[m][i][j] for each of one or more target line scans using the method described above. Further, the control unit  204  determines the distance included in the predetermined range from the calculated distance D[m][i][j]. Then, the control unit  204  sets the height direction of the emission direction of the electromagnetic wave corresponding to the result of measurement from which the determined distance is obtained, as the center of the scan range  224  in the height direction in the subsequent scan. The predetermined range described above may be set in advance in the control unit  204  or may be stored in the storage device that the control unit  204  can access. 
     Here, it is assumed that the distance included in the predetermined range is computed for each of two or more results of measurements. In this case, the control unit  204  determines the center of the scan range  224  in the height direction in the subsequent scan based on these two or more results of measurements. For example, similar to the case of using the predetermined distance as the predetermined condition. The control unit  204  sets the statistical value of the height direction of the emission direction of the electromagnetic wave for which each result of measurement where the distance included in the predetermined range is computed is obtained, as the center of the scan range  224  in the height direction in the subsequent scan. 
     When calculating this statistical value, similarly to the case where the predetermined distance is used as the predetermined condition, a part of the target line scans may be excluded from the calculation target of the statistical value. Specifically, among the target line scan for which the result of measurement where the distance included in the predetermined range is computed is obtained, it excludes the line scan for which the large number of results of measurements where a distance included in the predetermined range is computed is obtained (for example, a predetermined number or more), from the calculation target of the statistical value described above. 
     &lt;Determination Method 2&gt; 
     Using the method similar to the case of using the predetermined distance and the predetermined range of the distance as the predetermined condition in the determination method 1 described above, the control unit  204  determines the scan range  224  using the predetermined range of the predetermined time and the elapsed time as the predetermined range. As described in the explanation relating to the embodiment 2, the predetermined time can be calculated from the predetermined distance based on Equation (2). In addition, as described in the explanation relating to the embodiment 2, the upper limit value and the lower limit value of the predetermined range of elapsed time can be calculated using the upper limit value and the lower limit value of the predetermined range of the distance and the Equation (2). 
     &lt;Timing for Performing Determination of Scan Range  224 &gt; 
     The timing for the control unit  204  in the present embodiment to perform the determination of the scan range  224  is similar to the timing for the control unit  204  in the embodiment 2 performs the determination of the control unit  204 . 
     &lt;Example of Hardware Configuration&gt; 
     Similar to the hardware configuration of the measuring device  200  in the embodiment 1, the hardware configuration of the measuring device  200  in the embodiment 3 is illustrated, for example, in  FIG. 6  to  FIG. 8 . In addition, in the present embodiment, a program for realizing the functions described in the present embodiment is further included in the program module stored in the storage device  108  described above. 
     According to the measuring device  200  in the present embodiment, the center of the scan range  224  in the height direction is determined based on the result of measurement and the predetermined condition in the scan in the lateral direction. In this way, similarly to the case of using the measuring device  200  in the embodiment 2, even when the calibration is inaccurate, or the pose of the measuring device  200  changes due to vibration applied to the measuring device  200  during the operation, it is possible to make the object around a desired distance away from the measuring device  200  be included in the scan range  224 . In addition, it is possible to omit the effort of calibrating the measuring device  200 . 
     As described above, according to the measuring device  200  in the present embodiment, the determination of the scan range  224  can be performed using the measurement result for one line scan. Accordingly, compared to the measuring device  200  in the embodiment 2, there are advantages that the time required for determining the scan range  224  can be shortened and the amount of computer resources required for determining the scan range  224  can be reduced. 
     Furthermore, as described above, according to the measuring device  200  of the present embodiment, it is possible to easily exclude the line scan that includes many results of measurements that satisfy the predetermined condition such as the line scan that scans the large obstacle, from the line scan used for determination of the scan range  224 . In this way, it is possible to easily increase the accuracy of the determination of the scan range  224  by the control unit  204 . 
     Embodiment 4 
     Similarly to the measuring device  200  in the embodiment 1 to embodiment 3, a measuring device  200  in an embodiment 4 is represented by, for example,  FIG. 1 . The function of the measuring device  200  in the embodiment 4 is the same as the functions of the measuring devices  200  in any of the embodiment 1 to embodiment 3 except the points described below. 
     The measuring device  200  in the embodiment 4 is provided in the moving object  240  (refer to  FIG. 9 ). In addition, the control unit  204  in the embodiment 4 acquires information (hereinafter, speed information) indicating the speed of the moving object. Then, if the speed of the moving object indicated by the speed information is equal to or higher than a predetermined speed, the control unit  204  performs the determination of the scan range  224 . On the other hand, if the speed of the moving object indicated by the speed information is equal to or higher than the predetermined speed, the control unit  204  does not determine the scan range  224 . 
     The method of acquiring the speed information control unit  204  may be any method. For example, the control unit  204  acquires the speed information generated by the control device  244  through the CAN communication network  242 . A well-known technique can be used for a method in which the control device of the moving object recognizes the speed of the moving object and a method in which the control device of the moving object transmits the information to other devices. In addition, a device for measuring the speed of the moving object  240  may be provided inside the measuring device  200 . In this case, the measuring device  200  obtains the speed information from that device. 
     &lt;Processing Flow&gt; 
       FIG. 16  is a flowchart illustrating a processing flow executed by the control unit  204  according to the embodiment 4. The processing performed in S 102  and S 104  in  FIG. 16  is the same as the processing performed in S 102  and S 104  in  FIG. 5 . 
     In S 202 , the control unit  204  acquires the speed information. If the speed of the moving object indicated by the speed information is equal to or higher than the predetermined speed (S 204 : YES), the control unit  204  executes S 104 . On the other hand, if the speed of the moving object indicated by the speed information is lower than the predetermined speed (S 204 : NO), the processing in  FIG. 16  ends. 
     The control unit  204  may or may not perform the determination whether or not the speed indicated in the speed information is equal to or higher than the predetermined speed at the timing when the above-described scan range  224  is performed (the periodic timing or the timing at which the vibration is detected). In the latter case, for example, the control unit  204  performs the determination of whether or not the speed indicated in the speed information is equal to or higher than the predetermined speed once, and then, performs processes based on a result of the determination until the next determination is be performed. Specifically, if it is determined that the speed indicated in the speed information is equal to or higher than the predetermined speed, the control unit  204  determines the scan range  224  one or more times until the next determination is performed. Similarly, if it is determined that the speed indicated in the speed information is equal to or higher than the predetermined speed, the control unit  204  does not perform the determination of the scan range  224  until the next determination is performed. 
     If the speed of the moving object  240  is relatively slow, it is considered that large vibration is hardly applied to the moving object  240 . Therefore, if the calibration of the measuring device  200  is accurately performed, even if adjustment of the scan range  224  is not performed when the speed of the moving object  240  is slow, it can be said to be highly possible that the object positioned around a desired distance away from the measuring device  200  is scanned by the measuring device  200 . 
     Therefore, according to the present embodiment, the determination of the scan range  224  is performed when the speed of the moving object  240  is equal to or higher than the predetermined value. In this way, the frequency of performing the determination of the scan range  224  is reduced, and thus, the consumption of computer resources of the control unit  204  can be reduced. If it is considered that the necessity of adjustment of the scan range  224  is high (if the speed of the moving object  240  is equal to or higher than the predetermined value), the object positioned around a desired distance away from the measuring device  200  can be scanned by the measuring device  200  since the determination of the scan range  224  is performed. 
     Note that, assuming a case where the calibration of the measuring device  200  is not performed or the calibration of the measuring device  200  is inaccurate, the determination of the scan range  224  may be performed regardless of the speed of the moving object  240  at least once after startup. For example, after the startup of the control unit  204 , the scan range  224  is determined regardless of the speed of the moving object  240  the predetermined number of times or more or during a period equal to or more than a predetermined time. Thereafter, the control unit  204  performs the determination of the scan range  224  when the speed of the moving object  240  is equal to or higher than the predetermined value. In this way, even if the calibration of the measuring device  200  is not performed or the calibration of the measuring device  200  is inaccurate, at an early stage after the startup, the object positioned around a desired distance away from the measuring device  200  can be scanned by the measuring device  200 . 
     &lt;Example of Hardware Configuration&gt; 
     Similar to the hardware configuration of the measuring device  200  in the embodiment 1, the hardware configuration of the measuring device  200  in the embodiment 4 is illustrated, for example, in  FIG. 6  to  FIG. 8 . In addition, in the present embodiment, a program for realizing the functions described in the present embodiment is further included in the program module stored in the storage device  108  described above. 
     Embodiment 5 
     Similarly to the measuring device  200  in the embodiment 1 to embodiment 4, a measuring device  200  in an embodiment 5 is represented by, for example,  FIG. 1 . The function of the measuring device  200  in the embodiment 5 is the same as the functions of the measuring devices  200  in any of the embodiment 1 to embodiment 4 except the points described below. 
     The measuring device  200  in the present embodiment is provided in the moving object  240  similarly to the measuring device  200  in the embodiment 4. In addition, the control unit  204  in the embodiment 5 acquires the speed information similarly to the control unit  204  in the embodiment 4. Then, the control unit  204  determines a predetermined condition for determining the scan range  224  based on the speed of the moving object  240 . The predetermined condition is the predetermined distance, the predetermined range of the distance, the predetermined time, or the predetermined range of the elapsed time described in the description relating to the embodiment 2 and embodiment 3, for example. 
     The predetermined condition is determined in association with the speed of the moving object  240 . More specifically, the predetermined condition is defined such that the object to be scanned becomes farther away from the measuring device  200  as the speed of the moving object  240  becomes higher. This is because the moving object  240  moves longer distance in a short time as the speed of the moving object  240  becomes higher, and it is preferable to set the measuring device  200  to scan the object farther away. 
     For example, if the predetermined condition is the predetermined distance or the predetermined time, these values become larger as the speed of the moving object  240  increases. In another example, if the predetermined condition is the distance or the predetermined range of elapsed time, the lower limit and the upper limit of these predetermined ranges become larger as the speed of the moving object  240  increases. 
     Information indicating the association between the predetermined reference and the speed of the moving object is referred to as reference information.  FIG. 17  is a diagram illustrating the condition information in a table format. The table illustrated in  FIG. 17  is referred to as condition information  300 . The condition information  300  includes a speed  302  and a condition  304 . The speed  302  indicates the range of speed. The condition  304  indicates a predetermined condition in association with the range of speed indicated in the speed  302 . In  FIG. 17 , the condition  304  indicates the predetermined distance. For example, the record in the second line of the condition information  300  indicates that a predetermined condition “predetermined distance=a2[m]” is associated with the speed of the moving object  240  “higher than v1 and equal to or lower than v2”. 
     The condition information is not limited to selectively determine the predetermined condition according to the speed of the moving object as illustrated in  FIG. 17 . For example, the condition information may be an equation for computing the predetermined condition from the speed of the moving object  240 . In this case, for example, the condition information is defined as a function with the speed of the moving object  240  as an argument and the predetermined condition as a return value. 
     The condition information may be set in advance in the control unit  204  or may be stored in the storage device to which the control unit  204  can access. 
     &lt;Processing Flow&gt; 
       FIG. 18  is a flowchart illustrating a processing flow executed by the measuring device  200  according to the embodiment 5. The processing items performed in S 102 , S 104 , and S 202  in  FIG. 18  are the same as the processing items performed in S 102 , S 104 , and S 202  in  FIG. 17 . In S 302 , the control unit  204  determines the predetermined condition based on the speed of the moving object  240  indicated in the speed information. 
     The higher the speed of the moving object  240  is, the longer distance the moving object  240  travels in a short time. Therefore, the higher the speed of the moving object  240  is, it is preferable that the farther objects are scanned by the measuring device  200 . 
     Therefore, in the measuring device  200  in the present embodiment, the predetermined condition in determining the scan range  224  is determined according to the speed of the moving object  240 . In this way, it is possible to scan the object at an appropriate distance according to the speed of the moving object  240 . 
     &lt;Example of Hardware Configuration&gt; 
     Similar to the hardware configuration of the measuring device  200  in the embodiment 1, the hardware configuration of the measuring device  200  in the embodiment 5 is illustrated, for example, in  FIG. 6  to  FIG. 8 . In addition, in the present embodiment, a program for realizing the functions described in the present embodiment is further included in the program module stored in the storage device  108  described above. 
     Embodiment 6 
     A measuring device  200  in the present embodiment is represented by, for example,  FIG. 1 , similarly to the measuring device  200  in the embodiment 1. The function of the measuring device  200  in the embodiment 6 is the same as the function of the measuring device  200  in any of the embodiment 1 to embodiment 5 except the points described below. 
     In each embodiment described above, the control unit  204  determines the scan range in the subsequent scan in the height direction by the measuring unit  202  based on the height direction of the emission direction that satisfies the predetermined condition. In addition, “predetermined condition” is a condition representing that “an object positioned at a desired distance away from the measuring device  200  is scanned”. In addition, for example, the predetermined condition is a condition such as “the computed distance to the object is the predetermined distance (distance range)” or “it is the predetermined time between when the electromagnetic wave is emitted to a certain object and when the reflected electromagnetic wave reflected by the object is received by the measuring device  200 ”. 
     However, there is a case where the pose of the measuring device  200  (that is, the scan range of the measuring device) greatly changes (greatly deviates from the initial posture). Such change is caused, for example, by the vibration of a vehicle such the automobile on which the measuring device  200  is disposed. When such change occurs, at the timing of determining the scan range in the height direction in the subsequent scan by the measuring unit  202  as described above, there is a possibility that the signal received by the measuring unit  202  may not satisfy the predetermined condition described above. More specifically, any of the grids illustrated in  FIG. 11  may not satisfy the predetermined condition. For example, as illustrated in  FIG. 13 , in a case where a cross mark is indicated in a grid whose distance calculated for the target line operation is the same as the predetermined distance, there may occur a situation where there is no grid in which the cross mark is indicated. 
     Further specifically, when the pose of the measuring device  200  (that is, the emission range of the electromagnetic wave by the measuring device  200 ) largely changes upward, the distance computed for the target line scan can become a value longer than 100 m. Conversely, when the pose of the measuring device  200  changes largely downward, the distance computed for the target line scan may become a value shorter than 100 m in either case. 
     As described above, when the change occurs in the pose of the measuring device  200 , it becomes difficult to appropriately scan and measure the surroundings of the desired distance range (a position 100 m away from the measuring device  200  in the example above). 
     Therefore, in the measuring device  200  in the present embodiment, if the signal received by the measuring unit  202  does not satisfy the condition described above, the control unit  204  controls the measuring unit  202  such that the scan range of the measuring unit  202  (that is, the emission range of the electromagnetic wave emitted by the measuring unit  202 ) becomes upward or downward. In other words, if any of the emission directions of the electromagnetic wave in the scan range of the measuring unit  202  does not satisfy the predetermined condition, the control unit  204  moves the scan range of the measuring unit  202  upward or downward by a predetermined amount. 
     For example, at the timing to determine the scan range in the height direction in the subsequent scan by the measuring unit  202 , it is assumed that any of the distances computed for the target line scan becomes below the predetermined condition (for example, when the predetermined distance is set as 100 m, all are shorter than 100 m). In this case, the control unit  204  controls the measuring unit  202  such that the scan range of the measuring unit  202  becomes upward by a predetermined angle. That is, the control unit  204  starts the scan with a condition as a state in which the emitter  10  (the movable reflector  16 ) is tilted upward by a predetermined angle. 
     Then, the control unit  204  repeats the control until the signal received by the measuring unit  202  satisfies the condition described above (until any of the distances computed for the target line scan becomes satisfy the predetermined condition). That is, the scan range of the measuring unit  202  is shifted upward by a predetermined angle until the predetermined condition is satisfied. 
     Similarly, at the timing to determine the scan range in the height direction in the subsequent scan by the measuring unit  202 , it is assumed that any of the distances computed for the target line scan exceeds the predetermined condition (for example, when the predetermined distance is set as 100 m, all are longer than 100 m). In this case, the control unit  204  controls the measuring unit  202  such that the scan range of the measuring unit  202  becomes downward by a predetermined angle. That is, the control unit  204  starts the scan with a condition as a state in which the emitter  10  (the movable reflector  16 ) is tilted downward by a predetermined angle. Then, the control unit  204  repeats the control until the signal received by the measuring unit  202  satisfies the condition described above (until any of the distances computed for the target line scan becomes satisfy the predetermined condition). That is, the scan range of the measuring unit  202  is shifted downward by a predetermined angle until the predetermined condition is satisfied. 
     By performing such control, even if a situation occurs in which the pose of the measuring device  100  changes largely, it becomes possible to determine the height direction of the emission direction that satisfies the predetermined condition, and thus, it is possible to determine the scan range in the height direction in the subsequent scan by the measuring unit  202  based on the determined height direction. In this way, under various environments, the measuring device  200  can scan an object the predetermined distance away with the electromagnetic waves. 
     &lt;Example of Hardware Configuration&gt; 
     Similar to the hardware configuration of the measuring device  200  in the embodiment 1, the hardware configuration of the measuring device  200  in the embodiment 6 is illustrated, for example, in  FIG. 6  to  FIG. 8 . In addition, in the present embodiment, a program for realizing the functions described in the present embodiment is further included in the program module stored in the storage device  108  described above. 
     As described above, the embodiments of the present invention are described with reference to the drawings. However, these are examples of the present invention, and a combination of the above embodiments or various configurations other than the configurations described above may be adopted. 
     This application claims priority based on Japanese Patent Application No. 2016-169960 filed on Aug. 31, 2016, the disclosure of which is incorporated herein in its entirety.