JP2014037993A - Positioning device, positioning method, and positioning program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a positioning device capable of performing positioning with high speed and high precision even in an environment in which assist information cannot be obtained because of being outside a communication zone.SOLUTION: In a portable phone incorporating a positioning device, an assist information request part 105 requests an assist server for assist information on a moving-to-predicted position prior to arriving at the aforementioned position. The acquired assist information is stored in an assist information storage part 142. In a case where communication with the assist server is not possible when starting processing of positioning, a positioning processing part 108 performs the positioning using the assist information stored in the assist information storage part 142.

Description

  The present invention relates to a positioning device, a positioning method, and a positioning program, and more particularly, to a positioning device, a positioning method, and a positioning program that perform positioning using a GPS (Global Positioning System) satellite signal.

  As a positioning method using a GPS satellite, an A-GPS (Assisted-GPS) method is known. In this method, assist information (assist data) is acquired from an assist server on the network at the time of positioning to speed up satellite acquisition and shorten the positioning time. Further, by giving an initial position at the time of positioning, the positioning time can be further shortened.

  The assist information (assist data) is information used to calculate the position of the GPS satellite from the positioning position. Specifically, the assist information is orbit information of GPS satellites, and includes satellite time information, ephemeris, almanac, navigation data, ionospheric correction data, and the like.

  JP 2008-241719 A (hereinafter referred to as Patent Document 1) stores an acquired ephemeris and its acquisition time if the ephemeris can be acquired at the time of position measurement for the purpose of steadily shortening the position measurement time. After that, the elapsed time after the acquisition of the ephemeris is calculated every 1 minute, and the expiration date of the ephemeris is given to the user by generating an alarm sound every 2 minutes from the time when it has passed 2 hours. A positioning device that prompts a user to perform measurement operations continuously for 30 seconds or more in a place where the reception environment of radio waves is good before it is cut off is disclosed.

  Japanese Patent Laid-Open No. 2002-221562 (hereinafter referred to as Patent Document 2) stores at least eastern Japan and western Japan as representative position information for the purpose of promptly performing GPS positioning, and uses any one of these representative position information as GPS positioning. A GPS position detection device that performs GPS positioning using any representative position information selected and set as effective approximate position information is disclosed.

  Japanese Patent Laid-Open No. 2001-109764 (hereinafter referred to as Patent Document 3) uses the current location such as longitude / latitude information of a travel destination location based on travel schedule information for the purpose of acquiring the current location in a short time. By providing an information providing system that provides a travel data package in which valid data is associated with a schedule and stored in advance via the Internet, the travel data package distributed is stored in a portable terminal, and then traveled. The travel destination discloses a system that can determine the current location in a short time because the longitude and latitude information of the scheduled location of the schedule is known in advance.

  Japanese Patent Laid-Open No. 2000-275319 (hereinafter referred to as Patent Document 4) discloses that a GPS server receives navigation messages and received data received at a DGPS base station at regular intervals for the purpose of determining the current position in a very short time. The navigation message is corrected by collecting the data and calculating the position of the GPS satellite and stored, and the GPS receiver accesses the GPS server by communication when starting positioning to correct the optimal GPS satellite. A positioning system is disclosed in which a GPS receiver receives a received navigation message and obtains corrected ephemeris data included therein, so that the GPS receiver performs positioning based on the corrected ephemeris data.

  To receive assist information, the receiver needs to be connected to the network. Therefore, when the receiver is included in a terminal such as a mobile phone, assist information cannot be acquired if the terminal is out of the communication range by the network.

  Normally, when the network is out of communication range, a terminal equipped with a receiver performs autonomous positioning (Autonomous positioning) using only GPS satellite signals without using assist information. That is, when assist information cannot be obtained because a terminal equipped with a receiver goes out of communication range, for example, position information can be obtained by performing autonomous positioning.

JP 2008-241719 A JP 2002-221562 A JP 2001-109764 A JP 2000-275319 A

  However, in autonomous positioning, satellite supplementation takes time from several tens of seconds to several minutes, and it takes time to acquire position information.

  In addition, depending on the system, there is a problem in that the positioning accuracy may be lower in the autonomous positioning than in the positioning using the assist information.

  The present invention has been made in view of such problems, and even in an environment where assist information cannot be acquired from the network due to a terminal equipped with a receiver being out of communication range, etc., at high speed and high accuracy. Proposed positioning device, positioning method, and positioning program.

  In order to achieve the above object, according to one aspect of the present invention, the positioning device is a positioning device that uses a GPS signal, and provides a sensor for detecting the movement status of the positioning device and assist information. A first communication means for communicating with the assist server, a second communication means for communicating with the GPS satellite, and a memory for storing the assist information acquired from the assist server via the first communication means An assist information acquisition means for receiving a sensor signal input from the sensor and acquiring assist information from the assist server via the first communication means, and a GPS satellite via the second communication means. Positioning means for performing positioning processing using the acquired GPS signal. The assist information acquisition means acquires the assist information of the predicted movement position of the positioning device obtained from the sensor signal from the assist server prior to reaching the predicted movement position, and stores it in the memory. If the first communication means cannot communicate with the assist server at the start, the positioning process is performed using the assist information stored in the memory.

  Preferably, the positioning device further includes position calculation means for calculating a current position from the sensor signal and position information obtained by the positioning process by the positioning means, and the positioning means performs the first communication at the start of the positioning process. Assist information stored in the memory when the means cannot communicate with the assist server and the current position calculated by the position calculating means is included in the effective range of the assist information stored in the memory The positioning process is performed using.

  Preferably, the assist information acquisition unit specifies the predicted movement position at a time interval corresponding to the moving speed of the positioning device obtained from the sensor signal, and acquires assist information on the predicted movement position from the assist server.

  More preferably, the assist information acquisition unit specifies the movement predicted position according to the movement speed.

  More preferably, the assist information acquisition means specifies a position that is a predetermined distance away from the periphery of the positioning device as the predicted movement position when the movement speed is lower than a predetermined threshold value, and the movement speed is the threshold. In the case of a high speed larger than the value, a position separated by a predetermined distance in the movement direction is specified as the movement predicted position.

  According to another aspect of the present invention, the positioning method is a positioning method using a GPS signal in the positioning device, and the step of acquiring assist information from the assist server and storing it in the memory before the start of the positioning process. And a step of executing the positioning process using the assist information stored in the memory when communication with the assist server cannot be performed at the time of starting the positioning process, and the step of acquiring the assist information and storing it in the memory The assist information of the predicted movement position of the positioning device is acquired from the assist server before the predicted movement position is reached and stored in the memory.

  According to still another aspect of the present invention, the positioning program is a program for causing the positioning device to execute a positioning process using a GPS signal, and obtains assist information from the assist server and stores the memory before the start of the positioning process. To obtain the assist information by causing the positioning device to execute the steps of storing in the location and executing the positioning processing using the assist information stored in the memory when communication with the assist server cannot be performed at the time of starting the positioning processing. Then, in the step of storing in the memory, the assist information of the predicted movement position of the positioning device is acquired from the assist server before reaching the predicted movement position and stored in the memory.

  According to the present invention, positioning can be performed at high speed and with high accuracy even in an environment where assist information cannot be obtained from an assist server via a network because a terminal equipped with a receiver is out of a communication range.

It is a block diagram which shows the specific example of the apparatus structure of the portable terminal carrying the positioning apparatus concerning embodiment. It is a figure for demonstrating the assist information acquisition process in case a portable terminal is moving at a slow speed. It is a figure for demonstrating the assist information acquisition process in case the portable terminal is moving at high speed. It is a block diagram which shows the specific example of a function structure of a portable terminal. It is a flowchart showing the flow of the assist information acquisition process in a portable terminal. It is a flowchart showing the flow of the positioning process in a portable terminal.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, these descriptions will not be repeated.

<Device configuration>
FIG. 1 is a block diagram showing a specific example of the device configuration of a mobile terminal 100 equipped with a positioning device according to the present embodiment. In the example of FIG. 1, the mobile terminal 100 is assumed to be a mobile phone. However, the mobile terminal 100 is not limited to a mobile phone, and has a sensor to be described later, receives a function for connecting to a network, and a GPS signal. Any device may be used as long as it has a function of calculating information. For example, it may be a small notebook PC (Personal Computer), a document browsing device, a digital camera, a game machine, a pedometer, or the like.

  Referring to FIG. 1, mobile terminal 100 has a control unit 10 having a CPU (Central Processing Unit) for controlling the entire apparatus, an antenna, and performs wireless communication with a base station or the like to perform network communication. A wireless unit 11, an operation unit 12 having numeric keys and operation buttons, a display unit 13, a memory 14 such as a ROM (Read Only Memory) and a RAM (Random Access Memory), an antenna, and a GPS A GPS signal receiving unit 15 for receiving a GPS signal by communicating with a satellite and a sensor 16 are included.

  The sensor 16 is a sensor for detecting the movement status of the mobile terminal 100 itself, and corresponds to, for example, any one of an acceleration sensor, a speed sensor, and a direction sensor, or a combination of two or more thereof.

<Overview of operation>
The mobile terminal 100 equipped with the positioning device performs a process of obtaining assist information by performing network communication (assist information acquisition process) and a process of obtaining own position information (positioning process).

(1) Assist information acquisition process At the start of the assist information acquisition process, the mobile terminal 100 receives a GPS signal and measures the current location. After that, while tracking the position of the device using the sensor 16 and periodically communicating with the assist server at time intervals according to the moving speed, the assist information of the position corresponding to the moving speed is acquired from the assist server. Are sequentially stored in the memory 14. That is, the portable terminal 100 switches the method of acquiring assist information between when moving at a slow speed such as walking (for example, about 10 km / h) and when moving at a higher speed than that speed.

  FIG. 2 and FIG. 3 are diagrams for explaining the assist information acquisition process, each of which is an assist information acquisition process when moving at a low speed and an assist information acquisition process when moving at a high speed. FIG.

  Referring to FIG. 2, when mobile terminal 100 moves or stops at a slow speed within a speed V1 (for example, 10 km / h) representing a walking speed, mobile terminal 100 is mobile (V ≦ V1: low speed movement). The terminal 100 performs network communication with the assist server at a predetermined time T1 interval to acquire assist information of a position at a predetermined distance L around the current point from the cyst server.

  The reason why the position of the assist information is around the current point is that the moving direction is difficult to determine when moving at a low speed such as walking. As shown in the figure, there are four directions of the current location as shown in the figure.

  The distance L is set to about 10 Km in view of the effective range of the assist information having a radius of about 10 Km around the point where the positioning is performed. The time T1 is a time during which the moving distance (= moving speed V × time T1) of the mobile terminal 100 is within the effective range of the assist information (radius is about 10 km), and may be about 30 minutes, for example.

  Referring to FIG. 3, when mobile terminal 100 is moving at a speed where moving speed V is higher than speed V1 representing the walking speed (V> V1: high-speed movement), mobile terminal 100 is defined in advance. By performing network communication with the assist server at the time T2 interval, the assist information of the position L distance ahead in the current moving direction from the current point is acquired from the cyst server. The distance L is about the effective range of the assist information, but may be the same as or different from the distance L during low-speed movement.

  The reason why the position of the assist information is set at a distance L in the current movement direction from the current point is that the movement direction is difficult to change during high-speed movement. By acquiring the assist information of the position in one direction, the amount of communication can be suppressed without reducing accuracy.

  The time T2 is a time during which the moving distance (= moving speed V × time T2) of the mobile terminal 100 is within the effective range of the assist information (radius of about 10 km). For example, when the moving speed V is 100 km / h, the time T2 6 minutes. When the moving speed V is 50 km / h, the time T is 12 minutes.

  The portable terminal 100 can acquire from the cyst server in advance the assist information at a position that is likely to move by executing the above-described assist information acquisition process.

  Note that when the assist information is acquired, the mobile terminal 100 deletes the assist information acquired last time and stores new assist information (overwrites it). Thereby, it is possible to prevent the memory capacity from being compressed.

(2) Positioning process When the mobile terminal 100 can communicate with the assist server over the network, the mobile terminal 100 acquires assist information on the current location from an assist server (not shown) on the network, and uses the assist information to determine the position of the GPS satellite. After specifying, a positioning process is performed using a GPS signal. This positioning processing method is a method called an A-GPS (Assisted-GPS) system.

  On the other hand, when the network communication with the assist server is not possible because the network communication is out of service, the positioning process is performed using the stored assist information. This positioning process is also a normal method called A-GPS method, although the stored assist information is used.

  Note that the mobile terminal 100 predicts the moving position by switching the assist information acquisition process according to the moving speed as described above, and the assist server at the predicted position before reaching the position. And obtained and stored in the memory 14. Then, by defining the time interval and the predicted position to be acquired as described above, that is, four directions at the time of low speed movement, each distance shorter than the effective range of the assist information is set as the predicted position, and in the movement direction at high speed movement. By acquiring the next assist information at a time interval that is earlier than the distance of the effective range as a predicted position at a position that is shorter than the effective range of the assist information, the mobile terminal 100 can perform as predicted. When the movement is continued, the assist information whose current position is within the effective range is always stored in the memory 14. Therefore, as described above, when network communication with the assist server is not possible, the positioning process may be performed by the A-GPS method using the stored assist information.

  However, when the moving direction of the mobile terminal 100 is suddenly changed or the moving speed is suddenly changed, the current position at the time of performing the positioning process is acquired from the assist server immediately before and stored. There is also the possibility of leaving the effective range of information.

  Therefore, the mobile terminal 100 compares the position of the mobile terminal 100 being tracked using the sensor 16 with the position of the assist information stored in the memory 14 by the assist information acquisition process, and the current location is stored. The positioning process may be performed by the A-GPS method using the stored assist information when the assist information is within the effective range (the radius is about 10 km). By doing in this way, positioning accuracy can be improved.

  When assist information whose current position is in the effective range is not stored, the mobile terminal 100 performs autonomous positioning (Autonomous positioning) using only GPS satellite signals without using assist information.

  By performing the positioning process as described above, even if the mobile terminal 100 is out of the network communication range and cannot perform network communication with the assist server, as a result of the assist information acquisition process, the stored assist information If it is within the effective range, the positioning process can be performed using the assist information, so that positioning can be performed at high speed and with high accuracy.

<Functional configuration>
FIG. 4 is a block diagram illustrating a specific example of a functional configuration of the mobile terminal 100 for performing the above operation. Each function in FIG. 4 is mainly formed in the CPU when a CPU (not shown) included in the control unit 10 of the mobile terminal 100 reads and executes a program stored in the memory 14. However, at least a part may be realized by the hardware configuration shown in FIG.

  Referring to FIG. 4, the memory 14 stores a current position storage unit 141 that is a storage area for storing a current position obtained by tracking the movement of itself using the sensor 16, and the assist information acquisition process. And an assist information storage unit 142 that is a storage area for storing assist information obtained by performing the above.

  Further, referring to FIG. 4, the control unit 10 includes a sensor signal input unit 101 for receiving an input of a sensor signal from the sensor 16 such as an acceleration sensor or a speed sensor, and the sensor signal and its own calculated immediately before. A position calculation unit 102 for calculating the current position using the current seat position, a movement speed calculation unit 103 for calculating its own movement speed based on the sensor signal, and a movement speed that is high or low in advance. A threshold value (for example, 10 km / h or the like) for determining whether or not the moving speed is stored, the moving speed determining unit 104 for determining whether the moving speed is high speed or low speed, and its own moving speed An assist information requesting unit 105 for requesting assist information (not shown) to an assist server (not shown) via the wireless unit 11 in a method (time interval T1, T2, position) according to Assist information input unit 106 for accepting input of assist information from the bus via wireless unit 11, positioning method (A- Positioning method determining unit 107 for determining GPS method / A-GPS method / autonomous positioning using stored assist information) and positioning process for executing the positioning process with a positioning method according to the determination result Part 108.

  Among these functions, the sensor signal input unit 101 and the position calculation unit 102 correspond to a position specifying function for calculating the current position of the sensor signal input unit 101, the movement speed calculation unit 103, the movement speed determination unit 104, The assist information request unit 105 and the assist information input unit 106 correspond to an assist information acquisition function for acquiring assist information of the predicted movement position from the assist server. The positioning method determination unit 107 and the positioning processing unit 108 are connected to the assist server. This corresponds to a positioning processing function for executing positioning processing when network communication between the two is impossible.

<Operation flow>
FIGS. 5 and 6 are flowcharts showing the flow of assist information acquisition processing and positioning processing in the mobile terminal 100, respectively. The processing shown in the flowcharts of FIG. 5 and FIG. 6 is realized by causing the CPU included in the control unit 10 to read out and execute a program stored in the memory 14 to exhibit each function of FIG. The

  The assist information acquisition process of FIG. 5 is started at a timing when the mobile terminal 100 is activated as an example. As another example, it may be a timing at which the user instructs the start of the assist information acquisition process (automatic acquisition of assist information is enabled), a timing at which a GPS signal is received, or the like.

  Referring to FIG. 5, when the process starts, control unit 10 executes an initialization process (step S101). The initialization process corresponds to, for example, a process of deleting assist information stored in the previous assist information acquisition process from the memory 14.

  Next, the control unit 10 receives a GPS signal from a GPS satellite and acquires position information of the current location (step S103).

  Next, the control unit 10 receives an input of a sensor signal from the sensor 16 (step S105), calculates the current position from the current position previously calculated and stored, or the first acquired position information, and stores the memory in the memory. 14 (step S107).

  Further, the control unit 10 calculates a moving speed from the sensor signal (step S109), and the moving speed is a speed (high speed) faster than a speed V1 (for example, 10 km / h) representing the walking speed or within the speed V1. It is determined whether the speed is slow (low speed) (step S111).

  When the moving speed is low (NO in step S111), the control unit 10 requests the assist server for assist information at each position separated by a distance L that is predetermined in four directions from the current position. Then, assist information of these positions is acquired and stored (step S113). The saving here is overwriting saving to the previously saved assist information. When the predetermined time T1 has elapsed (YES in step S115), the control unit 10 returns the process to step S105 and repeats the subsequent processes. Thereby, when the moving speed is low, the control unit 10 acquires assist information of positions separated by distance L in each of the four directions of the current position at time T1 intervals, and sequentially stores the stored assist information. Update.

  When the moving speed is high (YES in step S111), the control unit 10 requests the assist server for assist information at a position separated by a predetermined distance L in advance in the moving direction obtained from the sensor signal. The assist information at that position is acquired and stored (step S117). The storage here is also overwriting the assist information stored earlier. When the predetermined time T2 has elapsed (YES in step S119), the control unit 10 returns the process to step S105 and repeats the subsequent processes. Thereby, when the moving speed is high, the control unit 10 acquires assist information of positions separated by a distance L in the traveling direction of the current position at time T2 intervals, and sequentially updates the stored assist information. To do.

  Referring to FIG. 6, when control unit 10 detects that a request to perform a positioning process is performed on portable terminal 100 (YES in step S <b> 201), control unit 10 determines whether network communication is possible at that time. Is determined (step S203).

  If communication is not possible due to out of network communication range or the like (YES in step S203), the control unit 10 reads the current position stored from the memory 14 (step S205), and sets the position as an effective range. It is determined whether or not assist information to be stored is stored in the memory 14 (step S207).

  When assist information whose effective range is the current position is stored in the memory 14 (YES in step S207), the control unit 10 performs a positioning process using the assist information (step S209). The positioning process here is a process based on a normal method called an A-GPS method.

  In addition, when it is not out of the network communication range (NO in step S203), the control unit 10 can perform a normal A-GPS positioning process (step S211).

  If the assist information having the current position as the effective range is not stored (NO in step S207), the control unit 10 performs autonomous positioning using only the GPS satellite signal without using the assist information ( Step S213).

<Effect of Embodiment>
The portable terminal 100 performs positioning processing by acquiring the assist information of the position predicted according to the movement status of the mobile terminal 100 from the assist server in advance by performing the above-described processing. It is possible to increase the possibility of storing assist information whose effective range is the position at the time. By storing the assist information whose effective range is the position at the time of positioning, the portable terminal 100 stores the assist information stored even when the mobile terminal 100 is out of the network area and cannot communicate with the assist server. Can be used to perform A-GPS positioning processing. Therefore, positioning can be performed with high speed and high accuracy compared to autonomous positioning when the network is out of the network area and cannot communicate with the assist server.

  Further, it is possible to provide a program for causing the control unit 10 of the positioning device to execute the above-described processing. Such a program is recorded on a computer-readable recording medium such as a flexible disk attached to the computer, a CD-ROM (Compact Disk-Read Only Memory), a ROM, a RAM, and a memory card, and provided as a program product. You can also. Alternatively, the program can be provided by being recorded on a recording medium such as a hard disk built in the computer. A program can also be provided by downloading via a network.

  The program according to the present invention is a program module that is provided as a part of a computer operating system (OS) and calls necessary modules in a predetermined arrangement at a predetermined timing to execute processing. Also good. In that case, the program itself does not include the module, and the process is executed in cooperation with the OS. A program that does not include such a module can also be included in the program according to the present invention.

  The program according to the present invention may be provided by being incorporated in a part of another program. Even in this case, the program itself does not include the module included in the other program, and the process is executed in cooperation with the other program. Such a program incorporated in another program can also be included in the program according to the present invention.

  The provided program product is installed in a program storage unit such as a hard disk and executed. The program product includes the program itself and a recording medium on which the program is recorded.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 10 Control part, 11 Wireless part, 12 Operation part, 13 Display part, 14 Memory, 15 Signal receiving part, 16 Sensor, 100 Portable terminal, 101 Sensor signal input part, 102 Position calculation part, 103 Movement speed calculation part, 104 Movement Speed determination unit, 105 assist information request unit, 106 assist information input unit, 107 positioning method determination unit, 108 positioning processing unit, 141 current position storage unit, 142 assist information storage unit.

Claims (7)

A positioning device that performs positioning using a GPS (Global Positioning System) signal,
A sensor for detecting the movement status of the positioning device;
A first communication means for communicating with an assist server that provides assist information;
A second communication means for communicating with a GPS satellite;
A memory for storing assist information acquired from the assist server via the first communication means;
Assist information acquisition means for receiving a sensor signal input from the sensor and performing processing for acquiring the assist information from the assist server via the first communication means;
Positioning means for performing positioning processing using GPS signals acquired from the GPS satellites via the second communication means,
The assist information acquisition means acquires the assist information of the predicted movement position of the positioning device obtained from the sensor signal from the assist server before it reaches the predicted movement position, and stores it in the memory.
The positioning device performs positioning processing using assist information stored in the memory when the first communication means cannot communicate with the assist server at the start of positioning processing. A position calculation means for calculating a current position from the sensor signal and the position information obtained by the positioning process in the positioning means;
The positioning means calculates the position calculation means within the effective range of the assist information stored in the memory when the first communication means cannot communicate with the assist server at the start of positioning processing. The positioning device according to claim 1, wherein when the current position is included, the positioning process is performed using assist information stored in the memory.   The said assist information acquisition means specifies the said movement prediction position in the time interval according to the moving speed of the said positioning device obtained from the said sensor signal, The assist information of the said movement prediction position is acquired from the said assist server. The positioning device according to 1 or 2.   The positioning device according to claim 3, wherein the assist information acquisition unit specifies the movement predicted position according to the movement speed.   The assist information acquisition means specifies a position that is a predetermined distance away from the periphery of the positioning device as the predicted movement position when the moving speed is lower than a predetermined threshold value, and the moving speed is The positioning device according to claim 4, wherein a position separated by a predetermined distance in the moving direction is specified as the predicted movement position when the speed is higher than a threshold value. A positioning method using a GPS signal in a positioning device,
Before starting the positioning process, obtaining assist information from the assist server and storing it in the memory;
When the positioning process cannot be performed at the start of the positioning server, the positioning process is performed using the assist information stored in the memory, and
In the step of acquiring the assist information and storing it in the memory, the assist information of the predicted movement position of the positioning device is acquired from the assist server before reaching the predicted movement position and stored in the memory. Positioning method. A program for causing a positioning device to execute a positioning process using a GPS signal,
Before starting the positioning process, obtaining assist information from the assist server and storing it in the memory;
If the positioning server cannot communicate with the assist server at the start of the positioning process, the positioning apparatus is caused to execute the positioning process using the assist information stored in the memory,
In the step of acquiring the assist information and storing it in the memory, the assist information of the predicted movement position of the positioning device is acquired from the assist server before reaching the predicted movement position and stored in the memory. Positioning program.

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