JP4491464B2 - Aircraft identification and docking guidance system - Google Patents

Description

  The present invention relates to a system for detecting, identifying and guiding (tracking) the position of an object (target). In particular, the present invention detects and identifies aircraft position detection, identification and docking guidance systems, as well as the location of objects (targets) at an airfield, and makes the aircraft safe and efficient at such an airfield. The present invention relates to a ground traffic control method for docking.

  In recent years, both passenger and cargo have increased significantly, and other aircraft traffic has increased, including takeoff and landing and other aircraft ground traffic. There has also been a marked increase in the number of ground support vehicles required for cargo unloading, delivery services and maintenance and support during the operation of all aircraft. As a result of such a significant increase in ground traffic, more control over the identification and docking of aircraft at the airfield is required, and more safety is required.

Examples of prior art systems proposed for detecting aircraft presence and other traffic conditions at an airfield include US Pat. No. 4,995,102, European Patent 188757, and PCT Published Applications WO 93/13104 and WO 93/145416 There are systems disclosed in each specification.
US Patent US4,995,102 European patent EP188,757 WO93 / 13104 WO93 / 15416

  However, these conventional systems detect the presence of aircraft on the airfield, especially under bad weather conditions such as fog, snow, or hail, hail, sleet, etc. It was not satisfactory. Furthermore, none of the systems disclosed in prior publications has been able to identify or confirm the specific configuration of the approaching aircraft. Furthermore, conventional systems have failed to provide sufficient technology to track and guide an aircraft to a designated stop point or stop location, such as an airport loading gate, and dock. In addition, the conventional system cannot provide a technique that can sufficiently calibrate the measuring device at the loading gate.

  Accordingly, it has been a long-standing problem to provide a system that can safely and reliably detect aircraft and other ground vehicles at an airfield over a wide range of atmospheric conditions.

  In addition to detecting an object such as an aircraft, for example, an aircraft detected with a certain degree of certainty regardless of the dominant weather conditions at that time and the amount of traffic on the ground (mobile body). It has been considered for many years that effective identification of detected objects such as, and systems for identifying and confirming such objects are necessary.

  The need for a system that can accurately and efficiently track and guide incoming aircraft and other objects to an appropriate stopping point, such as an airport loading gate, has been considered for many years. It has not been. Furthermore, providing accurate and efficient calibration and adjustment techniques for such systems has also been a problem that needs to be solved for many years.

SUMMARY OF THE INVENTION To solve the above-mentioned problems, an object such as an aircraft is positioned accurately, safely, effectively and without waste in an airfield, and the identity of such object (・ A system and method that can properly identify and confirm the model, affiliation, flight number, etc.) are required. There is a further need for a system and method for tracking an object such as an aircraft and guiding docking, particularly in a real-time mode of operation. There is a further need for a system and method for calibrating such operating systems.

  Accordingly, it is a main object of the present invention to provide such a system and method. In this context, it is a special object of the present invention to provide a docking guidance system that not only confirms the identity of the aircraft in the airfield, but can also accurately detect its exact location. Another object of the present invention is to provide communication means between the system and a personal computer and other devices for one or more persons who control the docking and parking of an aircraft in an airfield. The method is to supply information via the display unit and monitor the overall operation.

  Another object is to ensure the safety of a digitally accurate docking control system and to construct such a control system in a very cost effective manner.

  Yet another object is to display aircraft docking information, including information about the distance to the approaching aircraft stop point for use by pilots, copilots or other people docking the aircraft. Is to do. An important purpose other than the above is to perform automatic comparisons and measurements to ensure that the positioning and approach direction of the aircraft of the type being docked does not deviate from the required proper path (line). A display (indicator) that is located in front of the aircraft and displays distance information about how far to the left or right from the appropriate centerline for docking and type identification of that type of aircraft ) To countdown, and feed back the information about the distance to the docking position in a form that can be seen with the naked eye.

  Yet another object is to provide a system for scanning the apron that not only provides direction to the pilot or copilot, but also allows the aircraft to be docked properly and safely. Another object is to provide a particularly sensitive system so that an accurate parking position can be set with very little tolerance.

  Further objectives are very flexible and the addition of new aircraft types and alternative or secondary parking stop locations and other information regarding the identification, guidance and docking of aircraft in the airfield, etc. It is to provide a system that can incorporate new operating parameters.

  The above and other objectives of the present invention are to project a light pulse, such as a laser pulse, from a mirror, for example, from a mirror, toward an incoming object located within the capture area of the airfield. This is accomplished by using a system and method that detects the presence of an object by collecting light pulses that reflect the presence of that object. Similarly, according to this technique, it is possible to detect an aircraft within the above-mentioned capture area and know the position of the aircraft.

  The present invention also provides a system for verifying the identity of a detected object, for example, information that can determine that a properly formed aircraft is approaching a docking facility and that the aircraft should be docked there. And a method. Such a verification system and method includes an apparatus and method for projecting a light pulse, such as a laser pulse, in an angular coordinate format onto an object and collecting the reflected pulses from the object on a detection device. In order to determine whether or not the detected shape matches the shape of a certain known object, the detection apparatus uses this reflected pulse as a contour or contour feature (corresponding to the known object shape). Profile).

  In addition, the present invention provides a system and method for tracking an incoming object, which projects a light pulse, such as a laser pulse, onto the incoming object and collects the light reflected from that object. In a method used to determine the position of the object relative to the virtual axis projected from the predetermined docking point and to determine the distance between the object and the predetermined point in order to determine the position of the object. is there.

  Thus, the present invention detects or captures an approaching aircraft and identifies or confirms the aircraft within a designated capture or control area, which is the basis for initiating an aircraft docking procedure. That's right.

  Thereafter, in accordance with the present invention, a display is provided that allows the identified aircraft to be docked into an appropriate docking area where passengers can unload cargo, etc.

  The present invention fulfills the above-mentioned functions without using a sensor that has been generally required so far and must be embedded in the apron of the docking area. This can greatly reduce the maintenance costs after installation as well as the time and associated costs required for installation. In addition, the present invention does not require the apron work, and in the case of the conventional device that has been used in the docking guidance system so far, the use of the airport docking area that was necessary in connection with the work is interrupted. It is possible to install this new system on an existing system without causing a situation.

  In a preferred embodiment of the system of the present invention, the pilot who moves the aircraft to the airport gate, for example, is mounted on the gate and determines the position of the aircraft relative to the point where he must start braking. A real-time display can be used. The display also displays the lateral position of the aircraft relative to a predetermined path (line) that the aircraft of that type should take in order to get the aircraft to the gate most quickly.

  The software employed in the system of the present invention preferably consists of four modules that perform the main computational work of the system and control the hardware. These modules include acquisition, identification, tracking and system calibration.

  In a preferred embodiment of the invention, a capture module is used to instruct the apparatus to project a light pulse to scan the area in front of the docking gate. That is, when using a mirror to reflect and project a pulse, such as a laser pulse, the acquisition module scans the area until the laser pulse detects an object entering the area. Continue to point the laser at. Once the laser pulse detects the object, the acquisition module calculates the distance and angular position of the object and sends a control signal to the tracking module.

  Once activated, the tracking module tracks incoming aircraft to the gate and generates information regarding the aircraft's lateral position and distance relative to a scheduled stopping point. With this information, the pilot can correct the course of the aircraft and brake at an accurate point so that the aircraft will stop at a scheduled docking position that is aligned with the gate. During this tracking period, the identification module first scans the detected object to determine whether its contour matches the expected type of aircraft reference contour. If the contours do not match, the system communicates it to the control tower and sends a signal to stop the docking action.

  Finally, the calibration module calibrates the distance and angle measurements so that the reading of a detection device such as a laser range finder correctly corresponds to the position and angle of the aircraft. This module works periodically during the operation of the acquisition module and the tracking module to ensure that the system continues to operate correctly.

  Hereinafter, the features and effects of the present invention will be clarified by describing the present invention in detail with reference to the drawings.

  Table I is a preferred embodiment of a table representing the horizontal reference contour (outline) employed to perform aircraft identification in the system of the present invention.

  Table II is a preferred embodiment of the comparison table employed in the system of the present invention for docking an aircraft effectively and efficiently.

  First, FIG. 1 to FIG. 10 and tables I and II will be referred to. The same reference numerals denote the same elements throughout the drawings and tables. Throughout the following detailed description, each numbered step shown in the illustrated flowchart is schematically indicated by an element number in parentheses after the associated description.

  Referring to FIG. 1, the system of the present invention, indicated generally by the reference numeral 10 in FIG. 1 and other drawings, detects a position by calculating an object, confirms the identification of the object, and Track the object. The object is preferably an aircraft 12. In operation, the control tower 14 determines that the aircraft is approaching the gate 16 for the system after landing the aircraft (airplane) 12, the expected (scheduled) aircraft type, Information on the type or type (for example, Boeing 747, Lockheed L1011) is notified. The system 10 then scans the area in front of the gate 16 until the position of the object identified as the aircraft 12 is determined. The system 10 then compares the contour (outline features, profile) of the aircraft 12 with a reference contour for the expected aircraft type. If the aircraft whose position has been determined does not match or match the expected contour, the system 10 sends information or signals to the control tower 14 and interrupts the docking function.

  If the object is an anticipated aircraft 12, the system 10 tracks the aircraft to the gate 16 by displaying the remaining distance to the proper stopping point and the lateral position of the aircraft in real time for the pilot. ·Induce. The lateral position 31 of the aircraft 12 is displayed on the display 18 so that the pilot can modify the position of the aircraft 12 to approach the gate 16 from the correct angle. Once the aircraft 12 reaches the stop point 53, this is displayed on the display 18 and the pilot stops the aircraft. With the system 10 of the present invention, it should be noted that once the aircraft 12 is stopped, the aircraft is accurately aligned with the gate 16 and the ground worker does not need to adjust the position of the gate 16. is there.

  Referring to FIG. 2, the system 10 comprises a laser range finder (LRF) 20, two mirrors 21, 22, a display 18, two stepping motors 24, 25, and a microprocessor 26. The LRF used here is commercially available from Laser Atlanta Corporation, which emits a laser pulse and is reflected from an object at a distance. The reflected wave of the pulse can be received and the distance to these objects can be calculated.

  The system 10 is configured by connecting a series of ports (terminals) of the LRF 20 and the microprocessor 26 with a connection line 28. The LRF 20 sends measurement data to the microprocessor 26 approximately every 1/400 second through this connection line 28. The hardware of system 10, generally designated by reference numeral 23, is controlled by a programmed microprocessor 26. In addition, the microprocessor 26 supplies data to the display 18. As an interface to the pilot, the unit of the display 18 is installed on the gate 16 and is approaching an aircraft 30 of the type that the system is guessing how far the aircraft is from its stopping position, Furthermore, the pilot is informed of the lateral position 31 of the aircraft. Using this display, the pilot can adjust the approach of the aircraft 12 to ensure that the aircraft can reach the gate 16 at the correct angle. If the display 18 is displaying the wrong type of aircraft 30, the pilot can stop approaching before the aircraft is damaged. If the system mistakenly controls a larger 747 aircraft as a 737 aircraft, it would cause enormous damage and damage, so this double check will ensure the safety of passengers, aircraft and airport equipment.

  In addition to the display 18, the microprocessor 26 processes the data from the LRF 20 and supplies the data to the stepper motors 21, 22 via the connection line 32 to control the direction of the laser 20. Step motors 24 and 25 are coupled to the mirrors 21 and 22 and move the mirrors in response to commands from the microprocessor 26. Thus, by controlling the stepper motors 24, 25, the microprocessor 26 can change the angle of the mirrors 21, 22 to aim the laser pulses from the LRF 20.

  Mirrors 21 and 22 aim the laser by reflecting the laser pulse out beyond the airport apron (tarmac). In the preferred embodiment, the LRF 20 does not move and the laser scan is performed by a mirror. One mirror 22 controls the horizontal angle of the laser, and the other mirror 21 controls the vertical angle. By energizing the stepper motors 24, 25, the microprocessor 26 controls the mirror angle and thereby the direction of the laser pulse.

  The system 10 continuously scans in the horizontal direction within an angle range of ± 10 degrees with an angular step of about 0.1 degrees. This 0.1 degree angle step is equivalent to 16 microsteps per step when using an Escape EDM-453 step motor. One angular step is performed for each response from the reading unit, ie approximately every 2.5 milliseconds. The vertical mirror 21 is controlled to perform vertical scanning between +20 degrees and −30 degrees at an angular step of about 0.1 degree at a rate of one step every 2.5 milliseconds (ms). The vertical mirror 21 is used for vertical scanning when the aircraft nose height is being determined and when the aircraft 12 is being identified. During the tracking mode, the vertical mirror 21 is continuously adjusted to maintain a horizontal scan that tracks the nose tip of the aircraft 12.

  Referring to FIG. 3, the system 10 divides the field in front of it into three parts in terms of distance. The farthest area about 50 meters away is the capture zone. The system 10 senses the aircraft nose in this capture area and determines approximate estimates of the lateral and longitudinal positions of the aircraft 12. Inside the capture area 50 is an identification area 51 in which the system 10 matches the outline of the aircraft 12 with the stored outline. The system 10 indicates the lateral position of the aircraft 12 in this area relative to a given line on the display 18. Finally, a display or tracking area 52 is provided closest to the LRF 20. In the display position or tracking area 52, the system 10 displays the lateral and vertical positions of the aircraft 12 relative to the correct stop position with the highest accuracy. The end of the display area or tracking area 52 is a stop point 53. At stop point 53 the aircraft is in the correct position at gate 16.

  The system 10 includes a database that includes reference contours for all types of aircraft that the system 10 may encounter in addition to hardware and software. The system 10 stores the contours of each type of aircraft in this database, such as horizontal and vertical contours showing the expected echo pattern for the aircraft type.

  Next, description will be made with reference to Table I. The system 10 maintains horizontal contours in the form of table I. Row 40 of Table I represents the angular steps, and column 41 represents the distance from the stop position for the aircraft type. In addition to the displayed row 40, Table I includes a row 42 that provides a vertical angle for the aircraft nose at each position from the LRF 20, a row 44 that provides a shape or form factor k for the contour, And a row 45 which gives the contour value number (number) for each contour distance. The main part 43 of Table I contains the expected distance for the aircraft type at each scan angle and the distance from the stop point 53.

  Theoretically, table I needs to include 50 angular steps and 50 distances to the stop position 53, ie a total of 50 × 50 = 2500 entries. However, since the contour does not expect a response from all angles at all distances, in fact table I generally contains much less values. A typical table is actually expected to contain between 500 and 1000 values. Known programming techniques can provide a method of maintaining a partially complete table without using as much memory as is necessary to store the entire table.

  The system 10 maintains a vertical profile for each type of aircraft in addition to a horizontal profile. This contour is the same as the horizontal contour, except that the row is graduated by vertical angular steps, and the column ticks contain a smaller number of stops from the horizontal contour. It is stored in the form. Since the vertical contour is used only to determine the identification of the aircraft 12 and its nose height within the specified range of the distance from the LRF 20 in the identification region 51, the number of vertical contour columns is small. It's okay. As a result, the vertical contour stores only expected echoes within that range without wasting storage space for values that are not needed.

  System 10 uses the hardware and database described above to locate, identify and track the position of the aircraft using the process described below.

  Next, a description will be given with reference to FIG. The software functioning on the microprocessor executes a main routine that includes calibration mode 60, capture mode 62 and docking mode 64 subroutines. The microprocessor first executes a calibration mode 60, then executes a capture mode 62, and then executes a docking mode 64. When the aircraft 12 is docked, execution of the program ends. Next, these modes will be described in detail below.

In order to ensure accuracy on the calibration mode system, the microprocessor 26 is configured to self-calibrate according to the procedure illustrated in FIG. 5 before acquiring the aircraft 12 and at various intervals during its tracking. It has been programmed. By calibrating the system 10, the correspondence between the stepper motors 24, 25 and the target direction can be reliably known. Also check the distance measurement capability of the LRF 20.

  Next, a description will be given with reference to FIG. System 10 uses a square plate 66 in a known position to perform calibration. The plate 66 is attached at the same height as the LRF 20 at a position 6 m away from the LRF 20.

To perform the calibration, the system first sets the angle (α, β) to (0,0) and directs the laser beam straight forward. The system then tilts the vertical mirror 22 so that the laser beam is directed toward the rear rear mirror or accessory mirror 68 and further directed from this mirror to the calibration plate 66 (100). Microprocessor 26 uses stepper motors 24 and 25 to move mirrors 21 and 22 until the center of calibration plate 66 is found. When microprocessor 26 finds the center of calibration plate 66, it stores the angle (α _cp , β _cp ) at that center point and compares it to the stored expected angle (102). Further, the system 10 compares the detected (notified) distance to the center of the plate 66 with the stored expected value (reference value) (102). If the detected value does not match or match the stored value, the microprocessor 26 modifies the calibration constant that determines the expected value (angle) until both angles match or match (104). 106). However, if the deviation between the detected value and the value stored in the device is excessive, an alarm (ALARM) is issued (108).

Acquisition Mode Initially, the air traffic control tower 14 communicates to the system 10 that the arrival of the airplane 12 is expected and the expected airplane type. With that signal, the software enters the acquisition mode 62 shown in FIG. In acquisition mode 62, microprocessor 26 uses stepper motors 24, 25 to direct the laser beam to horizontally scan acquisition area 50 for airplane 12. This horizontal scan is made at a vertical angle that corresponds to the height of the expected type of aircraft nose at the center of the capture zone 50.

Microprocessor 26 calculates the vertical angle of the laser pulse according to the following equation to determine the exact height of the scan.
β _f = arctan [(H−h) / l _f ]
Where H = the height of the LRF 20 from the ground, h = the expected nose height of the aircraft (l is a lowercase letter L), and l _f = the distance from the LRF 20 to the center of the capture area 50. From this equation, the vertical angle of the mirror 21 is obtained, and a search (search) is performed at the vertical angle, thereby enabling a search at the expected height of the aircraft 12 at the center position of the capture area 50. . As an alternative, the system 10 may store β _f values for different types of aircraft at a distance in a database. However, when using the stored β _f , the system 10 will capture the aircraft 12 only at a predetermined distance from the LRF 20, which limits the flexibility of the system 10. Become.

Microprocessor 26 uses this vertical angle with respect to capture area 50 to direct the laser to perform a horizontal scan with a pulse interval of about 0.1 degrees. The microprocessor 26 performs horizontal scanning by changing the horizontal angle α from the center line (center line) of the LRF 20 in a range between ± α _max set in the apparatus. Typically, α _max is set to 50. Α _{max at} this time corresponds to 5 degrees when a pulse of 0.1 degrees is used. That is, the scanning angle is 10 degrees.

When a laser pulse is emitted, an echo or reflected wave returns from an object present in the capture zone 50. The detection device of the LRF 20 captures the reflected pulse, calculates the distance to the object from the time difference between the transmission (sending) of the pulse and the reception (receiving) of the echo, and the distance value calculated for each echo Is sent to the microprocessor 26. The microprocessor 26 stores (70) the total number of echoes or hits for each sector of the capture area 50 in each separate register in the data store. Since pulses occur at 0.1 degree intervals, a maximum of 10 echoes are generated for each sector. The microprocessor 26 stores the total number of hits in the form of a variable represented by S _alpha. Here, α is a value of 1 to 10, and is a value in increments of 1 degree of the capture area 50 of 10 degrees.

  In addition to storing the number of hits per sector, the microprocessor 26 stores the distance from the position of the LRF 20 to the object in each hit or echo in a data storage device. To store the distance for each reflection, a storage medium of sufficient capacity to store up to 10 hits or 100 possible values for each capture area 50 once is required. In many cases, most of the entries are empty, so using well-known programming techniques can reduce this storage capacity that is fixedly allocated for these values to less than 100 registers. it can.

When data of one scanning is available, the microprocessor 26 calculates the echo total number S _T by summing the S _alpha at the scanning. Next, the microprocessor 26 calculates the maximum echo total number S _M in each of the three adjacent sectors (72). That is, S _M is the maximum value of the sum of (S _α−1 , S _α , S _{α + 1} ).

After calculating S _M and S _T , the microprocessor 26 determines whether the echo is returned from the incoming airplane 12. If S _M is less than or equal to 24, the microprocessor 26 returns to the beginning of the capture mode 62 as having not found the airplane 12. If the maximum value S _M of the total number of echoes is greater than 24 (74), the “possible to exist” plane 12 position is determined. If the position of "possibly present" airplane 12 has been determined, the microprocessor 26 3 adjacent with the sum of S _M / S _T value if greater than 0.5, or the maximum number of It is checked whether one sector contains at least half (half) of all echoes (total) received during the scanning period.

Is greater than S _M / S _T is 0.5, the microprocessor 26 calculates the location of the center of the echo (78, 82). The azimuth angle (angular position) of the center of the echo is calculated according to the following formula.
α _t = α _V + (S _{α + 1} −S _α-1 ) / (S _α-1 + S _α + S _{α + 1} )
Here, Sα is Sα given S _M , and α _V (a _v ) is an angular sector corresponding to Sα.

ここで、ｌ_aviは、セクタα_Vから返って来たエコーの元のパルスに対する測定値または対象物までの距離である。また、ｎは、各セクタにおける測定値の合計数である（７８、８２）。測定値の数は最大１０個なので、ｎは１０以下である。 The longitudinal position of the center of the echo (l _t , l is the lower case letter of L) is calculated according to the following formula:

Here, l _avi is a measured value for the original pulse of the echo returned from the sector α _V or a distance to the object. N is the total number of measured values in each sector (78, 82). Since the maximum number of measurement values is 10, n is 10 or less.

On the other hand, when S _M / S _T <0.5, the echo is considered to be caused by snow noise or other artifacts (unnecessary signals generated elsewhere) existing in a narrow range. If the cause of the echo is due to an aircraft in a narrow range, the aircraft is probably quite close to the centerline, and α _t is 0 (zero) instead of the above calculated value, l _It can be assumed that _t is the average distance obtained by the central three sectors (80). If the distance distribution or distance is excessive, the microprocessor 26 returns to the beginning of the capture mode 62 (81), assuming that the aircraft 12 was not found.

  After calculating the position of the aircraft 12, the system 10 switches to the docking mode 64.

Docking Mode The docking mode shown in FIG. 4 comprises three phases: a tracking phase 84, a height measurement phase 86 and an identification phase 88. In the tracking phase 84, the system 10 monitors the position of the incoming aircraft 12, and via the display 18, information about the axial location 31 (azimuth information) and the aircraft's position. The distance from the stop point 53 is provided to the pilot. System 10 begins tracking aircraft 12 by horizontal scanning.

Referring to FIG. 8, during the first (first) scan in the tracking phase 84, the microprocessor 26
(Α _t −α _p −10) and (α _t + α _p +10)
Instructs the LRF 20 to deliver laser pulses at a predetermined single angle step (step) α or preferably at intervals of 0.1 degrees (step). Where α _t is the azimuth angle of the echo center determined during the capture mode 62 and α _p is the maximum azimuth angle (angular position) in the current contour column containing the distance value. .

After the first scan,
(Α _t −α _p −10) and (α _s + α _p +10)
Each time an LFR value is received, the angle α is stepped back and forth by one step. Here, α _s is the azimuth (azimuth) determined during the previous scan.

During the tracking phase 84, the vertical angle β is set to the level required to track the identified aircraft 12 at the current distance from the LRF 20 obtained from the reference contour table I. Current contour column is the column representing a position closest to the smaller than and l _t l _t.

The microprocessor 26 uses the distance from the stop point 53 to find the vertical angle for the current distance of the aircraft on the contour table I. During the first scan, the distance l _t calculated in the acquisition mode 62 determines the appropriate column of the contour table I and thus its angle with respect to the aircraft 12. Microprocessor 26 uses β in the row of contour table I according to the current distance from stop point 53 for each subsequent scan (112).

The microprocessor 26 creates the comparison table II using the data obtained by scanning and the data on the horizontal contour table I. Referring to Table II, this comparison table II is a two-dimensional table, and each row shows a pulse number (number) or angle step number (number) i indicated by a scale (index) 91. Using this scale, you can access the following information represented by columns in each row of the table.
l _i 92: Measurement distance to the object at the angular step (l is a small letter of L).
l _ki 93: a measured value (= l _i −amount (s _m (total displacement amount in the latest scanning period)) − amount i × s _p (period of each step in the latest scanning) Mean displacement amount)); that is, l _i- (s _m -is _p ))
di 94: Distance between the generated contour and the reference contour (= r _ij (contour value for the corresponding angle in the contour distance represented by j) −l _ki ).
a _i 95: distance between the nose of the aircraft and the measuring device (= r _j50 (reference contour value at 0 (zero) degree) −d _i ).
a _c 96: estimated nose distance after each step (= a _m (nose distance at the end of the latest scan) −amount i × s _p ).
a _d : difference between the estimated nose distance and the measured nose distance (= the absolute value of (a _i −a _e )).
Note 97: Indicates an echo that may have been caused by an aircraft.

During the first scan in tracking phase 84, the system 10 uses a row of horizontal contour representing the position j of the closest aircraft to the value of l _t of and smaller than the value l _t. For each new scan, the selected contour train having a value closest to (a _m -s _m) and smaller than (a _m -s _m). Here, a _m is the distance to the aircraft 12 measured most recently, and s _m is the displacement of the aircraft in the latest scanning period. Further, the profile value is moved in the horizontal direction by α _s to compensate for the vertical position of the aircraft (112).

Further, the microprocessor 26 creates a distance distribution table (DDT, Distance Distribution Table) in each scanning period. This table includes the distribution of a _i values in the comparison table II. Accordingly, the DDT has an entry representing the number of occurrences of each value of a _i in the comparison table II in increments of 1 m in the range of 10-100 m.

System 10 uses the DDT after each scan, compute the average distance a _m to correct stopping point 53. Microprocessor 26 scans the data in the DDT to find the one with the largest sum of the values of two adjacent entries in the DDT. Next, the microprocessor 26 flags the Note 97 column in the comparison table II for each row that contains an entry for a _i corresponding to one of the two rows with the largest sum in the DDT. (114).

The system 10 then determines the lateral deviation or offset. The microprocessor 26 first sets the following values.
2d = α _max −α _min
Here, α _max and α _min are the maximum and minimum values of α for blocks of di values with consecutive flags in the comparison table II, respectively. Further, the microprocessor 26 performs the following calculation.
For the upper half of flagged d _{i in} the block Y ₁ = Σd _i
For the lower half of the flagged d _{i in} the block, Y ₂ = Σd _i
Using “Y ₁ ” and “Y ₂ ”, “a” (116) is calculated as follows.
a = k × (Y ₁ −Y ₂ ) / d ²
Here, k is a value given in the reference contour. If “a” exceeds a predetermined value, preferably 1, it is assumed that there is a lateral deviation approximately equal to “a”. Next, the l _i column of the comparison table II is moved by “a” steps, and the comparison table II is recalculated. This process continues until “a” is less than an empirically determined value, preferably 1. The total amount of movement α _{s in} the l _i columns is considered to be equal to the lateral deviation or offset (116). If the lateral offset is greater than a predetermined value, preferably 1, the contour is adjusted laterally (118, 120) before performing the next scan.

  After checking the lateral offset, the microprocessor 26 supplies the sum of the lateral adjustments of the contour. This sum corresponds to the lateral position 31 of the aircraft 12 on the display 18 (122).

Next, the microprocessor 26 calculates the distance a _m to aircraft nose according to the following equation.
a _m = Σ (flagged a _i ) / N
Here, N is the total number of flagged a _i . Microprocessor 26, based on a _m, the distance to the aircraft nose by subtracting the distance LRF20 to stopping point 53, calculates the distance from the aircraft 12 to the stop point 53. (124).

Microprocessor 26, after calculating the distance to the stopping point, calculates the average displacement s _m in the latest scanning period. The displacement in this latest scan is calculated by the following formula.
S _m = a _m-1 −a _m
Here, a _m−1 and a _m belong to the two most recent scans. S _m is set to 0 (zero) for the first (first) scan in the tracking phase 84.

Average displacement s _p in each step is calculated in the following equation.
S _p = S _m / P
Here, P is the total number of steps for the latest scanning cycle.

  The microprocessor 26 notifies the pilot of the distance to the stop point 53 by displaying on the displays 18 and 29. By displaying the distance to the stop positions 29, 53 after each scan, the pilot always receives constantly updated information regarding the distance from the stop position of the airplane 12 in real time.

  If the aircraft 12 is present in the display area 52, a lateral position 31 and a longitudinal position 29 are provided on the display 18 (126, 128). After the microprocessor 26 displays the position of the aircraft 12, the tracking phase ends.

  After completing the tracking phase, the microprocessor 26 divides the total number of flagged rows by the total number of measurements or echoes in the latest scan that the tracking did not fail (the aircraft was not lost). Confirm by checking that the value is greater than 0.5 (83). That is, if more than 50% of the echoes do not correspond to the reference contour, tracking fails. If tracking fails and the aircraft 12 is at a distance greater than 12 meters from the stop point, the system 10 returns to acquisition mode 62 (85). If tracking fails and the aircraft 12 is no more than 12 meters away from the stop point, the system 10 turns on the stop sign (display) to notify the pilot that the tracking has failed (85). 87).

  If the tracking has not failed, the microprocessor 26 determines whether the nose height has been determined (130). If the height has not yet been determined, the microprocessor 26 enters a height measurement phase 86. If the height has already been determined, the microprocessor 26 checks whether the aircraft has been identified (132).

  In the height measurement phase shown in FIG. 9, the microprocessor 26 instructs the LRF 20 to scan vertically to determine the height of the nose. The system uses the nose height to ensure a horizontal scan across the tip of the nose.

Microprocessor 26 sets β to a predetermined value β _max to check the height of the nose, then 0 once per received / reflected pulse until β reaches another predetermined value β _min. Decrease the steps at 1 degree intervals. β _min and β _max are set in the apparatus setting period, and are typically −20 degrees and 30 degrees, respectively. After β reaches β _min , the microprocessor 26 instructs the stepper motors 24, 25 to increase steps until β reaches β _max . This vertical scanning is performed by setting α to the azimuth α _s of the previous scanning.

  Microprocessor 26 uses the measured aircraft distance to select the column in the vertical contour table that is closest to the measured distance (140). The microprocessor 26 creates the comparison table II using the data obtained by scanning and the data on the vertical contour table. Referring to FIG. 4, the comparison table II is a two-dimensional table, and the pulse number (number) or angle step number (number) i indicated by the scale 91 is shown in each row. This scale can be used to access the following information shown in each column in each row of the table.

l _i 92: Measurement distance to the object at this angular step.
l _ki 93: measured value (= l _i −amount (S _m (total displacement amount in the latest scanning period)) − amount i × s _p (period of each step in the latest scanning) Average displacement amount)); that is, l _i- (S _m -i _sp )).
d _i 94: distance between the generated profile and the reference profile (contour value for the corresponding angle at the profile distance represented by _{= r ij (j) -l ki} ).
a _i 95: distance between the nose of the aircraft and the measuring device (= r _j50 (reference contour value at 0 (zero) degree) −d _i ).
a _c 96: estimated nose distance after each step (= a _m (nose distance at the end of the latest scan) −amount i × s _p ).
a _d : difference between the estimated nose distance and the measured nose distance (= the absolute value of (a _i −a _e )).
Note 97: Indicates an echo that may have been caused by the aircraft 12.

Further, the microprocessor 26 creates a distance distribution table (DDT) in each scanning period. This table includes the distribution of a _i values in the comparison table II. Accordingly, the DDT has an entry representing the number of occurrences of each value of α _i in the comparison table II in increments of 1 m in the range of 10 to 100 m.

System 10 calculates the average distance a _m to correct stopping point 53 by using DDT after each scan. Microprocessor 26 scans the data in the DDT to find the one with the largest sum of the values of two adjacent entries in the DDT. Microprocessor 26 then flags Note 97 in Comparison Table II for each row that contains an entry for a _i corresponding to one of the two rows with the largest sum in DDT ( 142).

Upon completion the calculation of exact average distance to the stopping point 53, the microprocessor 26 calculates the average displacement s _m of the most recent scan period. The displacement in the latest scanning period is calculated by the following formula.
_{s m = a m-1 -a} m
Here, a _m−1 and a _m belong to the two most recent scans. S _m is set to 0 (zero) for the first scan in tracking phase 84.

Average displacement s _p in each step is calculated by the following equation.
s _p = s _m / P
Here, P is the total number of steps for the latest scanning cycle (period).

The actual nose height calculation is obtained by adding the nominal nose height, ie, the predetermined height of the expected aircraft when empty, to the vertical deviation or height deviation. Accordingly, the system 10 first determines a vertical deviation or height deviation (144) to determine the height of the nose. The vertical deviation is calculated with the following settings:
2d = β _max −β _min
Here, β _max and β _min are the maximum and minimum β values for the _di values of the consecutive flagged blocks in the comparison table II, respectively. Further, the microprocessor 26 performs the following calculation.
For the upper half of flagged d _{i in} the block Y ₁ = Σd _i
For the lower half of the flagged d _{i in} the block, Y ₂ = Σd _i
Using “Y ₁ ” and “Y ₂ ”, “a” is calculated as follows.
a = k × (Y ₁ −Y ₂ ) / d ²
Here, k is a value given in the reference contour. If “a” exceeds a predetermined value, preferably 1, it is assumed that there is a vertical deviation approximately equal to “a”. Next, the column l _i is moved by “a” steps, the comparison table II is displayed again on the screen, and “a” is recalculated. This process continues until “a” is smaller than a predetermined value, preferably 1. It is considered that the total movement amount β _s of the l _i columns is equal to the deviation in the height direction (144). Next, the β _j value in the vertical comparison table II is adjusted to β _j + Δβ _j . Here, the height deviation Δβ _j is expressed by the following equation.
Δβ _j = β _s × (a _mβ + a _s ) / (a _j + a _s )
Here, a _mβ is an effective value a _m when β _s is calculated.

  After determining the height deviation, the microprocessor 26 checks whether the height deviation is greater than a predetermined value, preferably 1 (146). If the deviation is greater than the predetermined value, the microprocessor 26 adjusts the contour in the vertical direction corresponding to the offset (148). The microprocessor 26 stores the deviation from the nominal nose height as a vertical adjustment (150). The actual height of the aircraft is the nominal nose height plus the deviation. Upon completion of the height measurement phase 86, the microprocessor 26 returns to the tracking phase 84.

  If the microprocessor 26 has already determined the height of the nose, it skips the height measurement phase 86 and determines whether the aircraft 12 has been identified (130, 132). If the aircraft 12 has been identified, the microprocessor 26 checks whether the aircraft 12 has reached a stop point (134). If the stop point has been reached, the microprocessor 26 turns on the stop sign and the system 10 completes the docking mode 64 (136). If the aircraft 12 has not reached the stop point, the microprocessor 26 returns to the tracking phase 84 (134).

  If the aircraft 12 has not been identified, the microprocessor 26 checks whether the aircraft 12 is at a distance of 12 m or less from the stop point 53 (133). If the aircraft 12 is no more than 12 meters away from the stop point 53, the system 10 turns on the stop sign and notifies the pilot that identification has failed (135). After displaying the stop sign, the system 10 interrupts the docking function.

  If the aircraft is at a distance greater than 12 meters from the stop point 53, the microprocessor 26 enters the identification phase shown in FIG. 10 (133, 88). In the identification phase 88, the microprocessor 26 creates a comparison table II to reflect the results of another vertical scan and the contents of the contour table (152, 154). Since the previous scan provided enough data to determine the height but not enough to perform the identification, another vertical scan is performed in the identification phase 88. In fact, several scans need to be performed before a positive (successful) identification is made. Calculate the vertical offset (156), check if the offset is excessive (158), and adjust the contour corresponding to the offset vertically until the offset is less than a predetermined amount, preferably 1, (160) Later, the microprocessor 26 determines the average distance between the contour and the marked echo and the average distance between this average distance and the marked echo. Are calculated (162).

After the vertical scanning and horizontal scanning, and the average distance d _m between the measured contour and modified contour, calculating the deviation T from this average distance according to the following equation.
d _m = Σd _i / N
T = Σ | d _i −d _m | / N
If T is a predetermined value for both contours, preferably less than 5, and a sufficient number of echoes are received, aircraft 12 is determined to be the correct type (164). Whether a sufficient number of echoes have been received is determined according to the following equation:
N / size> 0.75
Here, N is the number of “accepted” echoes, and “size” is the maximum number of possible values. If the aircraft 12 is not the correct type, the microprocessor turns on the stop sign 136 and interrupts the docking mode 64. The microprocessor 26 ends the identification phase 88 and returns to the tracking phase 84.

  Although the present invention has been described above using specific embodiments, it is obvious to those skilled in the art that many modifications can be made without departing from the spirit of the invention and the scope of the claims. is there.

FIG. 1 is a diagram showing a system used in an airport. FIG. 2 is a block diagram showing the general configuration of the preferred system of the present invention. FIG. 3 is a plan view showing a detection area in front of a docking gate provided for detecting and identifying an approaching aircraft. FIG. 4 is a flow chart illustrating the main routine and docking mode of the system. FIG. 5 is a flowchart illustrating the calibration mode of the system. FIG. 6 is a diagram illustrating components in the calibration mode. FIG. 7 is a flowchart illustrating the acquisition mode of the system. FIG. 8 is a flowchart illustrating the tracking phase of the system. FIG. 9 is a flowchart illustrating the height measurement phase of the system. FIG. 10 is a flowchart illustrating the system identification phase.

Claims (4)

An optical pulse generating means for generating an optical pulse;
Means for projecting and scanning the pulse outwardly onto an incoming object and reflecting the pulse from the object;
Means for collecting light pulses reflected from the object;
Means for detecting a position of the object relative to a virtual axis extending from a predetermined point, detecting a distance between the object and the predetermined point, and enabling tracking of the position of the object;
Have
Based on the collected light pulses, a comparison table that reflects the information about the scan and includes a distribution of the detected distance, and generates a comparison table that is compared with a contour table representing a known shape;
Based on the contour table the distribution of the detected distance by calculating the difference in the distance between the object and the known contour for each reflected pulse, the object against each reflected pulse based on a difference between the distance Generate a distance distribution table that records the distribution of the distance from the nose to the measuring device,
Calculate the average distance of the object to the planned stop position based on the distance distribution ,
Using the average distance in tracking the object;
A system for tracking incoming objects. Calculated by averaging the distance of the said average distance to the stop position, until the two was recorded for an entry in the comparison table corresponding to the adjacent entry said stop position having a maximum total value of the distance distribution table The tracking system of claim 1.   The tracking system according to claim 1 or 2, wherein a distance from the object to a stop point, a type of the object, and a position of the object with respect to a center are displayed on a display.   The average stop distance is communicated to a computer mounted on an aircraft, and the computer is configured to stop the aircraft when the aircraft reaches the stop position. Described tracking system.

Images