Movement control device, mobile body device, movement control system, and movement control method

Abstract

A movement control device (10A) controls a mobile body device (1A) that associates sensor data with time information indicating the time at which sensor data was acquired and position information indicating the position at which sensor data was acquired. The movement control device is characterized by being provided with a movement restriction unit (19) that restricts the movement of the mobile body device (1A) on the basis of a time synchronization error indicating an error in the internal time of the mobile body device (1A) with respect to a reference time outside the mobile body device (1A).

Description

MOBILITY CONTROL DEVICE, MOBILE BODY DEVICE, MOBILITY CONTROL SYSTEM, AND MOBILITY CONTROL METHOD

[0001] The present disclosure relates to a mobility control device, a mobile device, a mobility control system, and a mobility control method for controlling the movement of a mobile device that acquires sensor data while moving.

[0002] In recent years, with the spread of IoT (Internet of Things) devices and the reduction in the cost of various sensor devices, a wide range of applications of sensor data acquired by various sensor devices has been considered. When using sensor data, information such as when and where the sensor data was acquired is often used. For this reason, devices that acquire sensor data usually manage the sensor data by adding time information and location information to it.

[0003] For example, Patent Document 1 discloses a technology in which a terminal having a sensor stores in a storage unit time information when sensor data is received and location information indicating the location where the sensor data was detected, in association with the sensor data.

[0004] Japanese Patent Application Laid-Open No. 2018-182436

[0005] However, with the above-described conventional technology, when aggregating sensor data acquired by multiple devices, if the internal time of each device differs from device to device, there is a problem in that the error in the time information and location information associated with the sensor data acquired by each device increases. It is possible to synchronize the internal time if the device acquiring the sensor data performs a time synchronization process to synchronize with an external reference time. However, if the device acquiring the sensor data is a mobile device that acquires sensor data while moving and associates the acquired sensor data with time information and location information, depending on the location of the mobile device, it may be impossible to achieve sufficient synchronization accuracy due to, for example, the influence of the wireless communication environment used during the synchronization process. In this case, an error occurs in the internal time of the mobile device relative to the reference time, and the error in the time information and location information associated with the sensor data increases.

[0006] The present disclosure has been made in consideration of the above, and aims to provide a mobile control device that can reduce errors in time information and position information associated with sensor data acquired by a mobile device that acquires sensor data while moving.

[0007] In order to solve the above-mentioned problems and achieve the objectives, the mobile control device of the present disclosure is a mobile control device that controls a mobile device and associates time information indicating the time when the sensor data was acquired and location information indicating the location where the sensor data was acquired with sensor data, and is characterized by having a movement restriction unit that restricts the movement of the mobile device based on a time synchronization error that indicates the error between the internal time of the mobile device and a reference time external to the mobile device.

[0008] According to the present disclosure, it is possible to obtain a mobile control device that can reduce errors in time information and position information associated with sensor data acquired by a mobile device that acquires sensor data while moving.

[0009] FIG. 1 is a diagram showing a functional configuration of a mobile body device equipped with a mobile control device according to a first embodiment. FIG. 2 is a flowchart for explaining a first example of the operation of the mobile body device according to the first embodiment. FIG. 3 is a flowchart for explaining a second example of the operation of the mobile body device according to the first embodiment. FIG. 4 is a diagram showing a functional configuration of a mobile control system according to a second embodiment.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A mobile control device, a mobile body device, a mobile control system, and a mobile control method according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0011] 1 is a diagram showing the functional configuration of a mobile device 1A equipped with a mobile control device 10 according to a first embodiment. The mobile device 1A is a device having a mobility function. The mobile device 1A includes a wireless antenna unit 11, a wireless communication unit 12, a storage unit 13, a position information acquisition unit 14, a sensing unit 15, a time synchronization unit 16, a time-space stamp unit 17, a synchronization error estimation unit 18, a movement restriction unit 19, and a movement control unit 20.

[0012] The mobile device 1A has a function of acquiring sensor data while moving and associating the sensor data with time information at which the sensor data was acquired and location information at which the sensor data was acquired. Hereinafter, associating the sensor data with time information and location information will be referred to as spatiotemporal data synchronization.

[0013] The wireless antenna unit 11 receives wireless signals transmitted from an external device and radiates wireless signals transmitted by the mobile device 1A into space toward the external device. The wireless communication unit 12 uses the wireless antenna unit 11 to perform wireless communication with the external device. For example, the wireless communication unit 12 can transmit spatiotemporal synchronized sensor data to an external server that aggregates sensor data from multiple devices. Furthermore, when the time synchronization unit 16 performs time synchronization processing based on communication with a time synchronization server, the wireless communication unit 12 performs packet data transmission processing and reception processing, and inputs and outputs packet data to and from the time synchronization unit 16. Furthermore, when the mobile device 1A is remotely controlled from an external device, the wireless communication unit 12 receives information related to the movement of the mobile device 1A, such as a travel route, from the external device and outputs the information to the storage unit 13.

[0014] The storage unit 13 has the function of storing various types of information. For example, the storage unit 13 stores sensor data synchronized with the spatiotemporal data output by the spatiotemporal stamp unit 17. The storage unit 13 may also store movement history information in which only time information and location information are associated, even when sensor data is not acquired. The storage unit 13 may also hold information related to the movement of the mobile body device 1A, such as the movement route of the mobile body device 1A. The information related to the movement of the mobile body device 1A may be information set in advance, or, when the mobile body device 1A is remotely operated from the outside, may be information input each time via the wireless communication unit 12. The storage unit 13 can output information related to the movement of the mobile body device 1A to the movement control unit 20.

[0015] The position information acquisition unit 14 measures the current position of the mobile body device 1A and outputs the positioning result as position information to the space-time stamp unit 17. The position information acquisition unit 14 may acquire an absolute position represented by latitude and longitude using a Global Positioning System (GPS) or a Global Navigation Satellite System (GNSS) as the position information, or may acquire a relative position from a reference mobile body or a base station antenna as the position information. In addition to information indicating the position, the position information acquisition unit 14 can also acquire attitude information of the mobile body device 1A as the position information. The attitude information can be obtained using, for example, an inertial measurement unit (IMU) or the like.

[0016] The sensing unit 15 includes sensor devices for sensing various types of information. The sensing unit 15 outputs sensor data acquired by the various sensor devices to the spatiotemporal stamp unit 17. The sensing unit 15 can acquire one or more types of sensor data. Examples of sensor devices included in the sensing unit 15 include, but are not limited to, a temperature sensor, a humidity sensor, an image sensor, an acceleration sensor, a gyro sensor, and an IMU. The sensing unit 15 also includes required accuracy information indicating the accuracy required for spatiotemporal data synchronization for each application associated with each sensor device, and can output one or more pieces of required accuracy information to the movement restriction unit 19.

[0017] The time synchronization unit 16 executes a time synchronization process to synchronize the internal time of the mobile device 1A with an arbitrary external time, thereby correcting the internal time of the mobile device 1A. The external time used for synchronization is referred to as the reference time. The time synchronization unit 16 outputs the corrected internal time to the time-space stamp unit 17, and outputs the time correction value and other results of the time synchronization process to the synchronization error estimation unit 18. Examples of time synchronization methods include a time synchronization method using GPS signals, GNSS signals, etc., and a time synchronization method via wireless communication with a time synchronization server. Examples of time synchronization methods via wireless communication with a time synchronization server include NTP (Network Time Protocol), PTP (Precision Time Protocol), Wi-Fi (registered trademark) CERTIFIED TimeSync, and Bluetooth (registered trademark) Current Time Service. In the time synchronization method via wireless communication with a time synchronization server, the time synchronization unit 16 inputs and outputs packet data to and from the wireless communication unit 12 to exchange communication packet data with the time synchronization server based on the respective protocols. Examples of the results of time synchronization processing include the time offset value, the round-trip time (RTT) if a time synchronization server is used, the deviation of the offset value statistically processed using past results, the estimated offset value, the maximum estimated error, etc., and these correspond to the log of Chrony, which is one of the implementations of NTP.

[0018] The space-time stamp unit 17 performs space-time data synchronization to associate the corrected time information output by the time synchronization unit 16 and the position information of the mobile device 1A output by the position information acquisition unit 14 with the sensor data output by the sensing unit 15, and outputs the sensor data associated with the time information and position information by performing space-time data synchronization to the storage unit 13.

[0019] The synchronization error estimation unit 18 estimates the time synchronization error of the internal time relative to the reference time based on the corrected time information output by the time synchronization unit 16 and the results of the time synchronization process, and outputs the estimation result to the movement restriction unit 19. For example, the synchronization error estimation unit 18 may estimate the deviation σ or 3σ of the offset estimate or correction value from the past N times as the current time synchronization error, or may estimate the maximum offset value from the past N times as the current time synchronization error. The synchronization error estimation unit 18 may also estimate the maximum estimated error obtained by software processing such as Chrony or ntpd as the current time synchronization error. The synchronization error estimation unit 18 may update the time synchronization error estimate each time the time synchronization unit 16 outputs the results of the time synchronization process, or may update the estimate only when the difference between the previous time synchronization error estimate and the current time synchronization error estimate exceeds a threshold.

[0020] The movement restriction unit 19 calculates movement restriction information, which is information that restricts the movement of the mobile body apparatus 1A, based on the synchronization error estimated value output by the synchronization error estimator 18 and one or more pieces of required accuracy information output by the sensing unit 15, and outputs the calculated movement restriction information to the movement control unit 20. The movement restriction information is expressed, for example, by at least one of an upper limit value of the displacement of the mobile body apparatus 1A, an upper limit value of the movement speed, and an upper limit value of the acceleration. For example, assuming that the time synchronization error estimated value Δt output by the synchronization error estimator 18 and the current movement speed v, the position error x due to the time synchronization error will be err is expressed by the following equation (1): For simplicity, an equation based on velocity will be exemplified assuming that the velocity is considered to be constant during Δt.

[0021]

[0022] That is, the movement limiting unit 19 limits the movement speed v in accordance with the time synchronization error Δt, thereby reducing the position error x err For example, if the required accuracy of the application is the distance x req If so, the upper limit of the travel speed is the limited travel speed v lim By satisfying the following formula (2), the position error x err is the distance x, which is the required accuracy of the application. req This makes it possible to synchronize the time information and the location information with an accuracy within the required error. In addition, when there are multiple applications with required accuracy, the moving speed limit v is set based on the strictest requirement. lim It is advisable to calculate

[0023]

[0024]

[0025] Although the above example shows a case where the movement of the mobile body apparatus 1A is limited by a certain upper limit speed to control the position error, the object to be limited may be acceleration or displacement. In the case of a variable speed, a similar limitation may be performed by a certain upper limit acceleration, or the displacement of the mobile body apparatus 1A may be directly limited so that the displacement satisfies Equation (3).

[0026] Furthermore, if the difference between the previous synchronization error estimate and the current synchronization error estimate exceeds a predetermined threshold, the movement limiting unit 19 interval It is also possible to restrict the movement of the mobile body device 1A by stopping the mobile body device 1A for a period of time t intervalThe time synchronization polling period can be determined based on at least one of the clock accuracy of the time source of the mobile device 1A and the elapsed time since the last synchronization time. Furthermore, when multiple pieces of position information or sensor data are acquired while the mobile device 1A is stationary, the average value of each piece of position information or sensor data can be used as the result. Furthermore, the movement restriction unit 19 may change the time synchronization polling period if the difference between the previous synchronization error estimate and the current synchronization error estimate exceeds a predetermined threshold. Here, the mobile device 1A is brought to a standstill when the change in the synchronization error estimate exceeds a threshold. However, the mobile device 1A may also be brought to a standstill when the synchronization error estimate exceeds a predetermined threshold. In this case, the threshold may be set based on required accuracy information required by the application.

[0027] The movement restriction unit 19 can also restrict the movement of the mobile body device 1A based on the current position information of the mobile body device 1A and a movement restriction history indicating the details of past restrictions on the movement of the mobile body device 1A. The movement restriction history is information that associates position information with the details of past restrictions on the movement of the mobile body device 1A. The movement restriction unit 19 extracts movement restriction history that matches the position information based on the current position information, and restricts the movement of the mobile body device 1A by applying the restriction details indicated in the movement restriction history. In this way, the movement restriction unit 19 can restrict the movement of the mobile body device 1A using the details of past movement restrictions on the current position.

[0028] The movement control unit 20 controls the movement of the moving body device 1A based on information relating to movement such as a movement route output by the storage unit 13 and movement restriction information output by the movement restriction unit 19 .

[0029] 2 is a flowchart for explaining a first example of the operation of the mobile body device 1A according to the first embodiment. FIG. 2 shows the operation when controlling movement based on required accuracy information and an estimated value of the current time synchronization accuracy.

[0030] The movement control unit 20 sets the required accuracy information based on one or more pieces of required accuracy information output by the sensing unit 15 (step S101). For example, if the sensing unit 15 outputs one piece of required accuracy information, the movement control unit 20 sets the one piece of required accuracy information output by the sensing unit 15, and if the sensing unit 15 outputs multiple pieces of required accuracy information, the movement control unit 20 determines the required accuracy information to set from the multiple pieces of required accuracy information.

[0031] The synchronization error estimating unit 18 estimates a time synchronization error indicating the current time synchronization accuracy (step S102). The synchronization error estimating unit 18 outputs the estimated value of the time synchronization error to the movement restricting unit 19.

[0032] The movement restriction unit 19 calculates movement restriction information based on the required accuracy information and the estimated value of the time synchronization error (step S103). The movement restriction information indicates the parameters to be restricted and their restriction values, for example, upper limits.

[0033] The movement control unit 20 controls the movement of the mobile device 1A based on the movement restriction information (step S104). The movement control unit 20 determines whether the movement is completed (step S105). If the movement is completed (step S105: Yes), the process of Fig. 2 ends. If the movement is not completed (step S105: No), the process repeats from step S102.

[0034] 3 is a flowchart for explaining a second example of the operation of the mobile device 1A according to the first embodiment. FIG. 3 illustrates the operation when restricting movement by referring to past history. Note that FIG. 1 does not illustrate the data flow when performing the operation shown in FIG. 3. For example, when performing the operation shown in FIG. 3, data actually flows from the location information acquisition unit 14 to the movement restriction unit 19 and from the storage unit 13 to the movement restriction unit 19.

[0035] The movement restriction unit 19 of the mobile body device 1A sets past movement restriction information as the movement restriction information to be currently used based on the current location information acquired by the location information acquisition unit 14 (step S201). Specifically, the storage unit 13 stores a movement restriction history indicating the details of past restrictions on the movement of the mobile body device 1A. The movement restriction history is information that associates location information with the details of past restrictions on the movement of the mobile body device 1A, i.e., past movement restriction information. The movement restriction unit 19 can extract movement restriction history with matching location information based on the current location information and set the past movement restriction information included in the movement restriction history as the current movement restriction information.

[0036] The movement control unit 20 controls the movement of the mobile device 1A based on the set movement restriction information (step S202). The movement control unit 20 determines whether the movement is completed (step S203). If the movement is completed (step S203: Yes), the process of Fig. 3 ends. If the movement is not completed (step S203: No), the process repeats from step S201.

[0037] As described above, according to the first embodiment, it is possible to provide a mobile control device 10A that controls a mobile device 1A that associates time information indicating the time when the sensor data was acquired with position information indicating the position where the sensor data was acquired. The mobile control device 10A is characterized by including a movement restriction unit 19 that restricts the movement of the mobile device 1A based on a time synchronization error that indicates the error between the internal time of the mobile device 1A and a reference time external to the mobile device 1A.

[0038] This makes it possible to reduce errors in the time information and position information associated with the sensor data acquired by the mobile device 1A that acquires sensor data while moving. Furthermore, compared to acquiring sensor data by moving at a uniform moving speed, by controlling the movement of the mobile device 1A in accordance with the time synchronization accuracy, it is possible to move swiftly when the time synchronization accuracy is good, thereby shortening the time required to collect spatiotemporal data-synchronized sensor data.

[0039] The movement restriction unit 19 may restrict the movement of the mobile body device 1A by controlling the movement speed of the mobile body device 1A, may restrict the movement of the mobile body device 1A by controlling the displacement of the mobile body device 1A, may restrict the movement of the mobile body device 1A by stopping the mobile body device 1A, or may restrict the movement of the mobile body device 1A by controlling the acceleration of the mobile body device 1A.

[0040] Furthermore, the movement restriction unit 19 can also restrict the movement of the mobile device 1A based on the current position information of the mobile device 1A and a movement restriction history indicating past restrictions on the movement of the mobile device 1A. When movement control is performed based on the past movement restriction history, it is not necessary to perform a movement restriction calculation process each time, and therefore it is possible to correctly associate position information and time information with sensor data of the mobile device 1A with lower power consumption, and it is possible to extend the movement distance of the mobile device 1A.

[0041] According to the first embodiment, a mobile device 1A including the above-described mobile control device 10A can also be provided. The mobile device 1A can further include a sensing unit 15 that acquires sensor data, a location information acquisition unit 14 that acquires location information, and a space-time stamping unit 17 that associates time information and location information with the sensor data. The mobile device 1A can also include a wireless communication unit 12 that transmits the sensor data associated with the time information and location information by the space-time stamping unit 17. The wireless communication unit 12 can transmit the sensor data associated with the time information and location information to, for example, an external server that collects sensor data.

[0042] Embodiment 2 In the first embodiment, a configuration was described in which the mobile body apparatus 1A itself is equipped with a mobile control device 10A that limits the movement of the mobile body apparatus 1A. In the second embodiment, a configuration will be described in which a mobile control device 10B external to the mobile body apparatus 1B controls the movement of the mobile body apparatus 1B.

[0043] FIG. 4 is a diagram showing the functional configuration of a mobility control system 100B according to the second embodiment. The mobility control system 100B includes mobile devices 1B-1 and 1B-2 that acquire sensor data while moving, a server device 3, and a fixed mobility control device 10B. Hereinafter, when there is no need to distinguish between the mobile devices 1B-1 and 1B-2, they will be simply referred to as mobile device 1B. Note that although two mobile devices 1B-1 and 1B-2 are illustrated here, there is no restriction on the number of mobile devices 1B included in the mobility control system 100B. Below, detailed descriptions of the same parts as in the first embodiment will be omitted, and differences from the first embodiment will be mainly described.

[0044] The mobile body device 1B includes a wireless antenna unit 11, a wireless communication unit 12, a storage unit 13, a position information acquisition unit 14, a sensing unit 15, a time synchronization unit 16, a time-space stamp unit 17, and a movement control unit 20. In other words, the mobile body device 1B has a configuration in which the synchronization error estimation unit 18 and the movement restriction unit 19 are omitted from the mobile body device 1A according to the first embodiment. Note that, in order to clarify that movement restriction is performed by a movement control device 10B external to the mobile body device 1B, a configuration in which the synchronization error estimation unit 18 and the movement restriction unit 19 are omitted is shown here, but the mobile body device 1B may also include the synchronization error estimation unit 18 and the movement restriction unit 19. In this case, the mobile body device 1B can switch to the same operation as in the first embodiment when there is no instruction from the movement control device 10B.

[0045] The server device 3 has a communication unit 31 and a sensor data storage unit 32. The mobile control device 10B has a communication unit 41, a time synchronization unit 42, and a mobile object management unit 43. The mobile object management unit 43 has a movement restriction unit 19B.

[0046] The time synchronization unit 16 outputs the result of the time synchronization process, such as a time correction value, to the wireless communication unit 12. The time synchronization method may be a time synchronization method using GPS / GNSS signals, or a time synchronization method via communication with a time synchronization server. When using a time synchronization method via communication with a time synchronization server, the time synchronization unit 16 may perform the time synchronization process using the time synchronization unit 42 of the mobile control device 10B as the time synchronization server, or may use another time synchronization server synchronized with UTC (Coordinated Universal Time).

[0047] The wireless communication unit 12 transmits the results of the time synchronization process and the time correction value output by the time synchronization unit 16 to the communication unit 41 of the mobile control device 10B via the network. The wireless communication unit 12 also receives movement restriction information from the communication unit 41 of the mobile control device 10B via the network and outputs the received movement restriction information to the storage unit 13. The wireless communication unit 12 may also receive movement information such as a movement route from the mobile control device 10B. When receiving movement information, the wireless communication unit 12 outputs the received movement information to the storage unit 13. When sensor data synchronized with the spatiotemporal data of the mobile body device 1B is aggregated in the server device 3 via the network, the wireless communication unit 12 acquires sensor data with a spatiotemporal stamp from the storage unit 13 and transmits the acquired sensor data to the communication unit 31 of the server device 3. The wireless communication unit 12 may also transmit current location information of the mobile body device 1B output by the storage unit 13 to the communication unit 41 of the mobile control device 10B via the network, as necessary.

[0048] The storage unit 13 holds movement information such as a preset movement route, or when movement information is received from the movement control device 10B, holds movement information such as movement restriction information and a movement route output by the wireless communication unit 12, and outputs it to the movement control unit 20. Furthermore, in order to transmit the sensor data synchronized with the time-space data to the server device 3, the storage unit 13 outputs the sensor data to the wireless communication unit 12. Furthermore, in order to notify the movement control device 10B of current position information, the storage unit 13 may output the current position information to the wireless communication unit 12.

[0049] The movement control unit 20 controls the movement of the mobile body apparatus 1B based on the movement restriction information and movement information output by the storage unit 13. Here, the movement restriction information output by the storage unit 13 is received from the mobile control device 10B, and the movement control unit 20 controls the mobile body apparatus 1B in accordance with instructions from the mobile control device 10B.

[0050] The mobile control device 10B manages the movements of the multiple mobile devices 1B based on the results of the time synchronization process and time correction values ​​received from the mobile devices 1B.

[0051] The time synchronization unit 42 of the mobile control device 10B synchronizes with a reference time such as UTC. The time synchronization unit 42 may also function as a time synchronization server for the mobile device 1B. In this case, the time synchronization unit 42 performs time synchronization server processing on the time synchronization protocol packet output by the communication unit 41 and outputs a response packet to the communication unit 41.

[0052] The movement restriction unit 19B of the mobile body management unit 43 generates movement restriction information for each mobile body device 1B based on the time synchronization processing results and time correction values ​​of each mobile body device 1B output by the communication unit 41, and outputs the generated movement restriction information to the communication unit 41. The method of generating the movement restriction information by the movement restriction unit 19B may be the same as that of the movement restriction unit 19 in embodiment 1, or may be determined based on the time synchronization processing results and position information of the multiple mobile body devices 1B and the future movement route of the mobile body device 1B. The mobile body management unit 43 may also determine the movement route of the mobile body device 1B based on the current position information of each mobile body device 1B and output the determined movement route to the communication unit 41. The mobile body management unit 43 may also determine the type of sensor that will acquire data in each mobile body device 1B and notify each mobile body device 1B of the determined sensor type.

[0053] The communication unit 41 transmits the movement restriction information of each mobile body device 1B output by the mobile body management unit 43 and the movement route information of each mobile body device 1B input as needed to the wireless communication unit 12 of each mobile body device 1B via the network. Furthermore, when there is a time synchronization protocol response packet output by the time synchronization unit 42, the communication unit 41 transmits the response packet to the wireless communication unit 12 of the corresponding mobile body device 1B.

[0054] The spatiotemporal data-synchronized sensor data of each mobile device 1B may be stored in the storage unit 13 of each mobile device 1B and aggregated by offline access and retrieval, or may be collected via a network. When collecting sensor data via a network, the communication unit 31 of the server device 3 receives the spatiotemporal data-synchronized sensor data from each mobile device 1B via the network and outputs the received sensor data to the sensor data storage unit 32.

[0055] The sensor data storage unit 32 aggregates and stores the sensor data synchronized with the spatiotemporal data generated by each mobile device 1B.

[0056] FIG. 5 is a flowchart for explaining an example of an operation in which the mobile control device 10B according to the second embodiment restricts the movement of the mobile body device 1B.

[0057] The communication unit 41 of the mobile control device 10B receives the results of the time synchronization process from each mobile body device 1B (step S301) and outputs the received results of the time synchronization process to the mobile body management unit 43. The mobile body management unit 43 stores the received results of the time synchronization process for each mobile body device 1B, for example, in an internal storage medium (step S302). For example, the results of the time synchronization process may be managed in association with the identifier of the mobile body device 1B. Furthermore, if the location information of the mobile body device 1B is also included, the mobile body management unit 43 stores the results of the time synchronization process in association with the location information.

[0058] The movement restriction unit 19B of the mobile management unit 43 determines and stores movement restriction information for each mobile device 1B based on the stored results of the time synchronization process (step S303). The movement restriction unit 19B may determine movement restriction information based on past movement restriction information in addition to the stored results of the time synchronization process. For example, if the difference between the results of a past time synchronization process acquired near the current location of the mobile device 1B and the results of the current time synchronization process is equal to or less than a threshold, the movement restriction unit 19B may use the movement restriction information previously used at that location as the current movement restriction information. The movement restriction unit 19B stores the determined movement restriction information in association with the location information, making it possible to refer to it in the same way next time and thereafter.

[0059] The movement restriction unit 19B transmits the determined movement restriction information to the corresponding mobile apparatus 1B (step S304).

[0060] 6 is a flowchart for explaining the operation of the mobile body device 1B according to the second embodiment. First, the time synchronization unit 16 performs a time synchronization process (step S401), acquires the result of the time synchronization process, and performs time correction as necessary. The mobile body device 1B transmits the result of the time synchronization process to the mobile control device 10B (step S402). Note that a correction value may be transmitted in addition to or instead of the result of the time synchronization process.

[0061] The mobile body device 1B receives movement restriction information from the mobile control device 10B (step S403). The movement control unit 20 controls the movement of the mobile body device 1B based on the movement restriction information received from the mobile control device 10B (step S404). The movement control unit 20 determines whether the movement has been completed (step S405). If the movement has been completed (step S405: Yes), the mobile body device 1B ends the processing of FIG. 6, and if the movement has not been completed (step S405: No), the mobile body device 1B repeats the processing from step S401.

[0062] As described above, the mobile body devices 1B-1 and 1B-2 according to the second embodiment can achieve the same effects as the mobile body device 1A according to the first embodiment. Furthermore, in the mobility control system 100B, the mobility control device 10B centrally manages the movement of the multiple mobile body devices 1B, such as the movement restrictions and movement routes, thereby reducing the processing load on the mobile body device 1B and enabling the collection of spatiotemporal synchronized sensor data for a desired area in a short period of time. Furthermore, by collecting spatiotemporal synchronized sensor data via a network, it becomes possible to aggregate the sensor data in real time. Furthermore, when the sensor data is aggregated by offline processing from the storage unit 13 of the mobile body device 1B after the mobile body device 1B returns, it becomes possible to reduce network traffic compared to when the sensor data is collected via a network.

[0063] In the second embodiment, the mobile control device 10B is a device different from the mobile body device 1B. Therefore, the mobile control device 10B has a communication unit 41 that receives the result of the time synchronization process from the mobile body device 1B to be controlled. The movement restriction unit 19B restricts the movement of the mobile body device 1B based on the time synchronization error according to the received result of the time synchronization process.

[0064] The communication unit 41 can also receive the results of the time synchronization process from multiple mobile devices 1B. The movement restriction unit 19B restricts the movement of the mobile device 1B based on the time synchronization error for each mobile device 1B. The movement control device 10B may also function as a time synchronization server for the mobile device 1B to be controlled.

[0065] Embodiment 3 In Embodiment 2, the mobile control device 10B is a fixed device. In Embodiment 3, the mobile control device 10C has a movement function and performs movement control while moving together with the mobile body device 1B.

[0066] 7 is a diagram showing the functional configuration of a mobile control system 100C according to the third embodiment. The mobile control system 100C includes mobile bodies 1B-1 and 1B-2, a server device 3, and a mobile control device 10C. Here, the mobile control device 10C controls the movement of two mobile bodies 1B-1 and 1B-2, but there is no restriction on the number of mobile bodies 1B. Also, while the diagram shows a configuration in which one mobile body is dedicated to the mobile control device 10C, the mobile control device 10C may also be configured to acquire sensor data in the same way as other mobile bodies.

[0067] In the following, detailed description of the same parts as in the second embodiment will be omitted, and the parts different from the second embodiment will be mainly described.

[0068] The mobile body devices 1B-1 and 1B-2 are the same as those in embodiment 2. The mobile control device 10C has a movement function and is a mobile body for movement control. The mobile control device 10C has a wireless communication unit 41C, a time synchronization unit 42, a mobile body management unit 43, a wireless antenna unit 44, a sensor data aggregation unit 45, and a movement control unit 46.

[0069] In addition to the same functions as those in the second embodiment, the mobile management unit 43 has functions such as a function to instruct the time synchronization method of the mobile body device 1B, and a function to manage at least one of the movement restriction information and movement route of the mobile control device 10C and output it to the movement control unit 46. For example, when sensing is performed using the mobile body devices 1B-1 and 1B-2 in an environment with a poor GPS / GNSS communication environment, such as inside a tunnel, the mobile control device 10C may control the movement of the mobile control device 10C so that the mobile control device 10C stops at a point where acquisition of position information and time synchronization by GPS / GNSS is possible with sufficient accuracy and stable wireless communication with the mobile body device 1B during sensing can be performed, and the mobile control device 10C may instruct the mobile body device 1B on a time synchronization method so as to synchronize the time with the mobile control device 10C. Furthermore, without being limited to the above example, the mobile control device 10C may control the movement of the mobile control device 10C so that the respective performance does not fall below a certain threshold value based on the signal strength of the wireless communication with the mobile body device 1B, the frame error rate, the results of the time synchronization processing of each mobile body device 1B, the time correction value, the round-trip delay time, etc. Furthermore, the mobile control device 10C may control the movement of the mobile control device 10C so that the time synchronization accuracy between the mobile control device 10C and GPS / GNSS and the positioning accuracy of the location information do not fall below a certain threshold value.

[0070] The movement control unit 46 controls the movement of the movement control device 10C based on at least one of the movement restriction information and the movement route output by the moving body management unit 43.

[0071] The sensor data aggregation unit 45 receives the spatiotemporal synchronized sensor data of the mobile devices 1B-1 and 1B-2 via wireless communication, generates aggregated sensor data, and transmits the aggregated data to the server device 3.

[0072] 8 is a flowchart for explaining an example of the operation of the mobile control device 10C according to the third embodiment. Steps S501 to S504 are the same as steps S301 to S304 in FIG.

[0073] The mobile object management unit 43 determines whether or not it is necessary to switch the time synchronization method of each mobile object 1B (step S505). If it is necessary to switch the time synchronization method (step S505: Yes), the mobile object management unit 43 transmits a time synchronization method instruction to the target mobile object 1B (step S506). If it is not necessary to switch the time synchronization method (step S505: No), the mobile object management unit 43 omits the processing of step S506. The mobile object management unit 43 may determine whether or not it is necessary to switch the time synchronization method based on a comparison result with a predetermined threshold using an index such as an offset value deviation, an estimated offset value, an RTT, or a maximum estimated error, or may instruct the mobile object 1B to switch the time synchronization method based on the current location of the mobile object 1B before the mobile object 1B starts sensing in a predetermined area.

[0074] Next, the movement control unit 46 determines whether movement of its own device, i.e., the mobile control device 10C, is necessary (step S507). The movement control unit 46 can determine whether movement of the mobile control device 10C is necessary using at least one of the position information of one or more mobile devices 1B, the result of the time synchronization process, and the result of the time synchronization process of the mobile control device 10C. If movement of the mobile control device 10C is necessary (step S507: Yes), the movement control unit 46 performs movement control to move the mobile control device 10C (step S508). If movement of the mobile control device 10C is not necessary (step S507: No), the movement control unit 46 omits the processing of step S508.

[0075] As described above, the mobile control system 100C according to the third embodiment can have the same functions as those of the first and second embodiments. Furthermore, in the mobile control system 100C, the mobile control device 10C has a movement function and controls the movement of external mobile devices 1B-1 and 1B-2 while moving. This allows the mobile control device 10C to move near the mobile devices 1B-1 and 1B-2. For example, the mobile control device 10C includes a mobile management unit 43 that instructs the mobile device 1B to use a time synchronization method based on the result of the time synchronization process, so that the mobile device 1B to be controlled uses a time synchronization method appropriate for the time synchronization accuracy. The mobile control device 10C also includes a mobile control unit 46 that controls the movement of the mobile control device 10C. The mobile control unit 46 controls the movement of the mobile control device 10C based on at least one of the result of the time synchronization process of the mobile control device 10C, the position information of the mobile device 1B to be controlled, and the result of the time synchronization process of the mobile device 1B to be controlled. The mobile control device 10C may also function as a time synchronization server for the mobile body device 1B. As a result, even in areas where the synchronization accuracy of time synchronization methods such as GPS / GNSS has been reduced, such as tunnels where spatiotemporal data synchronization has traditionally been difficult, the mobile control device 10C can perform time synchronization with some kind of time synchronization method with a required accuracy or higher, and if the mobile control device 10C can communicate wirelessly with the mobile body device 1B, the mobile control device 10C can function as a time synchronization server for the mobile body device 1B, thereby achieving the required accuracy or higher for the time synchronization accuracy of the mobile body device 1B. Therefore, even in areas such as tunnels, it becomes possible to acquire sensor data with spatiotemporal data synchronization with an accuracy higher than required.

[0076] The mobile control device 10C also includes a wireless communication unit 41C that receives sensor data associated with time information and position information from multiple mobile devices 1B, and a sensor data aggregation unit 45 that aggregates the sensor data received from the multiple mobile devices 1B. The wireless communication unit 41C also aggregates the sensor data aggregated by the sensor data aggregation unit 45 and transmits the aggregated data collectively to the server device 3. This reduces communication traffic overhead compared to when each mobile device 1B individually transmits sensor data to the server device 3, reduces network load, and enables sensor data to be acquired in real time.

[0077] Next, a hardware configuration for realizing the functions of the mobile body devices 1A, 1B-1, and 1B-2 and the mobile control devices 10A, 10B, and 10C according to the first to third embodiments of the present disclosure will be described. The functions of each unit of the mobile body devices 1A, 1B-1, and 1B-2 and the mobile control devices 10A, 10B, and 10C are realized by a processing circuit. These processing circuits may be realized by dedicated hardware or may be control circuits using a CPU (Central Processing Unit).

[0078] When the above processing circuits are realized by dedicated hardware, they are realized by a processing circuit 90 shown in Fig. 9. Fig. 9 is a diagram showing dedicated hardware for realizing the functions of the mobile body devices 1A, 1B-1, and 1B-2 and the mobile control devices 10A, 10B, and 10C according to the first to third embodiments. The processing circuit 90 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof.

[0079] When the processing circuit is realized by a control circuit using a CPU, the control circuit is, for example, a control circuit 91 having the configuration shown in FIG. 10 . FIG. 10 is a diagram showing the configuration of the control circuit 91 for realizing the functions of the mobile body devices 1A, 1B-1, and 1B-2 and the mobile control devices 10A, 10B, and 10C according to the first to third embodiments. As shown in FIG. 10 , the control circuit 91 includes a processor 92 and a memory 93. The processor 92 is a CPU, and is also referred to as a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, DSP (Digital Signal Processor), etc. The memory 93 is, for example, a non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), or EEPROM (registered trademark) (Electrically EPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, or a DVD (Digital Versatile Disk).

[0080] When the above processing circuit is realized by the control circuit 91, it is realized by the processor 92 reading and executing a program stored in the memory 93 and corresponding to the processing of each component. The memory 93 is also used as a temporary memory for each process executed by the processor 92. The program executed by the control circuit 91 may be provided in a state stored in a storage medium or via a communication path such as the Internet. Furthermore, some of the above functions may be implemented by dedicated hardware and some may be implemented using a program.

[0081] The configurations shown in the above embodiments are examples of the contents of the present disclosure, and may be combined with other known technologies, and parts of the configurations may be omitted or modified within the scope of the gist of the present disclosure.

[0082] Furthermore, the technology described in the above embodiments may be applied to a system such as a cyber-physical system (CPS) that aggregates various types of sensor data from real space and reproduces the real space in cyberspace using a computer. In a CPS, the real space can be reproduced more accurately by using sensor data synchronized with time-space data that accurately corresponds time information and location information indicating when and where the sensor data was acquired.

[0083] Various aspects of the present disclosure are summarized below as appendices.

[0084] (Supplementary Note 1) A mobile control device that controls a mobile device that associates time information indicating the time at which sensor data was acquired with position information indicating the position at which the sensor data was acquired, the mobile control device comprising: a movement limiting unit that limits movement of the mobile device based on a time synchronization error that indicates an error between an internal time of the mobile device and a reference time external to the mobile device. (Supplementary Note 2) The mobile control device according to Supplementary Note 1, wherein the movement limiting unit limits movement of the mobile device by controlling a movement speed of the mobile device. (Supplementary Note 3) The mobile control device according to Supplementary Note 1, wherein the movement limiting unit limits movement of the mobile device by controlling a displacement of the mobile device. (Supplementary Note 4) The mobile control device according to Supplementary Note 1, wherein the movement limiting unit limits movement of the mobile device by bringing the mobile device to a standstill. (Supplementary Note 5) The mobile control device according to Supplementary Note 1, wherein the movement limiting unit limits movement of the mobile device by controlling an acceleration of the mobile device. (Supplementary Note 6) The mobile control device of any one of Supplementary Notes 1 to 5, wherein the movement restriction unit restricts the movement of the mobile device based on current position information of the mobile device and a movement restriction history indicating details of past restrictions on movement of the mobile device. (Supplementary Note 7) The mobile control device of any one of Supplementary Notes 1 to 6, further comprising: a communication unit that receives a result of a time synchronization process from the mobile device to be controlled, wherein the movement restriction unit restricts the movement of the mobile device based on the time synchronization error corresponding to the received result of the time synchronization process. (Supplementary Note 8) The mobile control device of Supplementary Note 7, wherein the communication unit receives results of the time synchronization process from a plurality of the mobile devices, and the movement restriction unit restricts the movement of the mobile device based on the time synchronization error for each of the mobile devices. (Supplementary Note 9) The mobile control device of Supplementary Note 7 or 8, wherein the mobile control device functions as a time synchronization server for the mobile devices to be controlled.(Supplementary Note 10) The mobile control device according to any one of Supplementary Notes 7 to 9, further comprising: a mobile management unit that instructs the mobile device to be controlled to use a time synchronization method based on a result of the time synchronization processing. (Supplementary Note 11) The mobile control device according to any one of Supplementary Notes 7 to 10, having a movement function and controlling movement of the external mobile device while moving. (Supplementary Note 12) The mobile control device according to Supplementary Note 11, further comprising: a movement control unit that controls movement of the mobile control device based on at least one of a result of the time synchronization processing of the mobile control device, position information of the mobile device to be controlled, and a result of the time synchronization processing of the mobile device to be controlled. (Supplementary Note 13) The mobile control device according to Supplementary Note 11 or 12, further comprising: a sensor data aggregation unit that aggregates the sensor data received from the plurality of mobile devices, wherein the communication unit receives the sensor data associated with the time information and the position information from a plurality of the mobile devices. (Supplementary Note 14) The mobile control device according to Supplementary Note 13, wherein the communication unit collectively transmits the sensor data aggregated by the sensor data aggregation unit to a server device. (Supplementary Note 15) A mobile body device comprising the mobile control device according to any one of Supplements 1 to 6. (Supplementary Note 16) The mobile body device according to Supplementary Note 15, comprising: a sensing unit that acquires the sensor data; a location information acquisition unit that acquires the location information; and a space-time stamp unit that associates the time information and the location information with the sensor data. (Supplementary Note 17) The mobile body device according to Supplementary Note 16, further comprising: a wireless communication unit through which the space-time stamp unit transmits the sensor data associated with the time information and the location information.(Supplementary Note 18) A mobility control system comprising: a mobile device that associates time information indicating the time when sensor data was acquired and position information indicating the position where the sensor data was acquired with the sensor data; and a mobility control device that controls the mobile device, wherein the mobility control device comprises: a movement restriction unit that restricts the movement of the mobile device based on a time synchronization error that indicates an error between an internal time of the mobile device and a reference time external to the mobile device. (Supplementary Note 19) A mobility control method that controls a mobile device that associates time information indicating the time when sensor data was acquired and position information indicating the position where the sensor data was acquired with the sensor data, comprising: restricting the movement of the mobile device based on a time synchronization error that indicates an error between an internal time of the mobile device and a reference time external to the mobile device.

[0085] 1A, 1B, 1B-1, 1B-2 Mobile device, 3 Server device, 10A, 10B, 10C Mobile control device, 11, 44 Wireless antenna unit, 12, 41C Wireless communication unit, 13 Storage unit, 14 Location information acquisition unit, 15 Sensing unit, 16, 42 Time synchronization unit, 17 Space-time stamp unit, 18 Synchronization error estimation unit, 19, 19B Movement restriction unit, 20, 46 Movement control unit, 31, 41 Communication unit, 32 Sensor data storage unit, 43 Mobile management unit, 45 Sensor data aggregation unit, 90 Processing circuit, 91 Control circuit, 92 Processor, 93 Memory, 100B, 100C Mobile control system.

Claims

1. A mobile control device that controls a mobile device and associates time information indicating the time when sensor data was acquired with location information indicating the location where the sensor data was acquired, the mobile control device comprising: a movement restriction unit that restricts the movement of the mobile device based on a time synchronization error that indicates the error between the internal time of the mobile device and an external reference time of the mobile device.

2. The mobile control device according to claim 1, wherein the movement limiting unit limits the movement of the mobile device by controlling the movement speed of the mobile device.

3. The mobile control device according to claim 1, wherein the movement limiting unit limits the movement of the mobile device by controlling the displacement of the mobile device.

4. The mobile control device according to claim 1, wherein the movement limiting unit limits the movement of the mobile device by bringing the mobile device to a standstill.

5. The mobile control device according to claim 1, wherein the movement limiting unit limits the movement of the mobile device by controlling the acceleration of the mobile device.

6. A mobile control device as described in any one of claims 1 to 5, characterized in that the movement restriction unit restricts the movement of the mobile device based on current position information of the mobile device and a movement restriction history indicating past restrictions on the movement of the mobile device.

7. A mobile control device as described in any one of claims 1 to 6, further comprising a communication unit that receives the result of the time synchronization processing from the mobile device to be controlled, wherein the movement restriction unit restricts the movement of the mobile device based on the time synchronization error corresponding to the received result of the time synchronization processing.

8. The mobile control device described in claim 7, characterized in that the communication unit receives results of the time synchronization processing from multiple mobile devices, and the movement restriction unit restricts the movement of the mobile devices based on the time synchronization error for each mobile device.

9. The mobile control device according to claim 7 or 8, characterized in that it functions as a time synchronization server for the mobile device to be controlled.

10. A mobile control device according to any one of claims 7 to 9, characterized in that it comprises a mobile management unit that instructs the mobile device to be controlled on the time synchronization method to be used based on the result of the time synchronization processing.

11. A mobile control device according to any one of claims 7 to 10, characterized in that it has a mobile function and controls the movement of the external mobile device while moving.

12. A mobile control device as described in claim 11, further comprising a mobile control unit that controls the movement of the mobile control device based on at least one of the results of the time synchronization processing of the mobile control device, the position information of the mobile device to be controlled, and the results of the time synchronization processing of the mobile device to be controlled.

13. A mobile control device as described in claim 11 or 12, characterized in that the communication unit receives the sensor data associated with the time information and the location information from multiple mobile devices, and further comprises a sensor data aggregation unit that aggregates the sensor data received from multiple mobile devices.

14. The mobile control device according to claim 13, wherein the communication unit collectively transmits the sensor data aggregated by the sensor data aggregation unit to a server device.

15. A mobile device comprising the mobile control device according to any one of claims 1 to 6.

16. A mobile device as described in claim 15, characterized in that it comprises: a sensing unit that acquires the sensor data; a location information acquisition unit that acquires the location information; and a time-space stamp unit that associates the time information and the location information with the sensor data.

17. The mobile device according to claim 16, further comprising a wireless communication unit by which the space-time stamp unit transmits the sensor data in which the time information and the position information are associated.

18. A mobility control system comprising: a mobile device that associates time information indicating the time when sensor data was acquired with location information indicating the location where the sensor data was acquired; and a mobility control device that controls the mobile device, wherein the mobility control device comprises a movement restriction unit that restricts the movement of the mobile device based on a time synchronization error that indicates the error between the internal time of the mobile device and a reference time external to the mobile device.

19. A mobility control method for controlling a mobile device that associates sensor data with time information indicating the time at which sensor data was acquired and location information indicating the location at which the sensor data was acquired, the mobility control method comprising a step of restricting the movement of the mobile device based on a time synchronization error indicating the error between the internal time of the mobile device and a reference time external to the mobile device.

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