JP4801929B2 - SENSOR DEVICE HAVING WIRELESS DATA TRANSMISSION FUNCTION, METHOD OF OPERATING THE SENSOR DEVICE, SENSOR SYSTEM COMPRISING THE SENSOR DEVICE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable acquiring detection data with high time precision while reducing power consumption in a sensor device having the radio transmission function of detection data. <P>SOLUTION: A sensor device 10 is provided with a sensor element 21, a CPU 24, a data acquiring part 22, a memory 28, a radio communication part 30 and a highly precise measuring part 26. The CPU 24 acquires a current time by a highly precise measuring part 26 (a), and decides whether or not the current time is approaching a target time based on the current time (b), and when the current time is not approaching the target time, the CPU 24 is set in a sleep mode, and after the lapse of a predetermined sleep time, the CPU 24 is switched to an active mode, and the processing (a) to (c) is repeated, and when the current time is approaching the target time, the current time is acquired by the highly precise measuring part 26, and detection data by the sensor element 21 are acquired when the target time comes, and the detection data are transmitted by the radio communication part 30. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to a sensor device, and more particularly to a sensor device having a function of wirelessly transmitting data detected by a sensor. The present invention also relates to a method of operating such a sensor device and a sensor system including a plurality of such sensor devices.

2. Description of the Related Art Conventionally, as disclosed in Non-Patent Document 1, for example, a sensor device that includes a sensor element such as an acceleration sensor and has a function of outputting detection data from the sensor element to the outside by wireless transmission is known. This sensor device includes an AD converter that converts a detection signal from a sensor element into a digital value, a wireless transmission unit that wirelessly transmits data converted into a digital value, a CPU that controls the entire device, and the like. According to such a sensor device having a wireless transmission function, even when a large number of sensor devices are arranged, it is not necessary to provide wiring for data output in each sensor device. There are merits such as.
Jason Hill et al, "System Architecture Directions for Networked Sensors", [online], [March 23, 2005 search], Internet <URL: http://www.tinyos.net/papers/tos.pdf#search = 'Jason% 20Hill% 20System% 20architecture'

  In the case of a sensor device capable of wireless data transmission as described above, if power is supplied from the outside such as a commercial power supply, power supply wiring is required, and the above-described advantages of wireless communication are diminished. It is assumed that a battery is used. Therefore, it is necessary to save power in the sensor device in order to suppress battery consumption.

  As a technique for reducing the power consumption of the sensor device, it is conceivable to use a sleep mode of a CPU provided in the sensor device. The CPU sleep mode is an operation mode in which power consumption is extremely low and only the timer function can be executed.

  As a first method using the sleep mode, when the timer function operating in the sleep mode detects that the preset data collection time has been reached, the sleep mode is changed to the active mode (the mode in which the CPU operates normally). ), A process of collecting data from the sensor element and performing wireless transmission is executed, and after this process is completed, a method of switching to the sleep mode again can be considered.

  However, since the timer built in the CPU has poor time accuracy, it is necessary to switch from the sleep mode to the active mode at a timing with a considerable margin with respect to the data collection time. For this reason, the time during which the CPU operates in the active mode becomes longer than necessary, and the power consumption increases accordingly.

  Further, as a second technique, a method of waiting for a data collection command from the outside and collecting sensor data in response to the command can be considered. In this method, the timer function is used to switch the CPU to the active mode every time the timer expires and measure the electric field strength. If the electric field strength does not exceed the threshold, the CPU switches to the sleep mode again. On the other hand, if the electric field strength exceeds the threshold, the radio wave content is analyzed, and if the content is the command, data is collected from the sensor and transmitted wirelessly.

  In this method, it is necessary to switch from the sleep mode to the active mode at regular time intervals in order to check whether a command is transmitted. For this reason, if the time interval is short, switching to the active mode is frequently performed, resulting in an increase in power consumption. On the other hand, if the time interval is increased in order to reduce power consumption, command transmission must be continued for a long time so that the sensor device can receive commands reliably. The power consumption of the entire system cannot be achieved.

  The present invention has been made in view of the above points, and an object of the present invention is to enable detection data to be collected with high time accuracy while keeping power consumption low in a sensor device having a detection data wireless transmission function. To do.

In order to achieve the above object, the present invention is a sensor device having a function of wirelessly transmitting detection data,
A sensor element;
A control unit configured by a CPU operable in an active mode for performing a normal operation and a sleep mode capable of executing only a timer function;
A data collection unit for collecting the output of the sensor element as detection data;
A wireless communication unit for wirelessly transmitting the collected detection data;
A clock unit for supplying current time information to the control unit,
The controller is
In the active mode of the CPU,
(A) a process of acquiring the current time from the clock unit;
(B) a process of determining whether or not the acquired target time is close to the specified target time;
(C) the processing of the (b), when the said is determined not to be close to the target time, switch the CPU into the sleep mode, in the processing of pre-Symbol (b), close to the target time after it is determined to be, the process of the current time acquired from the clock unit is the collected detection data by the data collecting section Once at the target time, and transmits the detected data collected by the wireless communication unit Run ,
When a predetermined sleep time elapses in the sleep mode of the CPU, the CPU is switched to the active mode, and then the processes (a) to (c) are repeated.

  According to the present invention, each time the sleep time elapses, the CPU is switched from the sleep mode to the active mode to acquire the current time from the clock unit. If the target time is not close, the CPU is switched to the sleep mode and the target time is close. If so, the detection data is collected when the current time reaches the target time. Therefore, most of the time until the detection data is collected, while the CPU is operated in the sleep mode with low power consumption, Detection data can be collected with high time accuracy based on the accurate current time acquired from the section.

In the present invention, the control unit may determine the target from the acquired current time when it is determined in the process of (c) that the process of (b) is not close to the target time. A time difference until the time may be calculated, and the predetermined sleep time may be set to a smaller value as the time difference is smaller. In this way, the sleep time becomes shorter as the target time is approached, so that the target time can be prevented from being reached during operation in the sleep mode. In this case, by setting a value obtained by multiplying the time difference by a constant smaller than 1 as the sleep time, it is possible to more reliably prevent the target time from being reached during the operation in the sleep mode.

The present invention is also a sensor device having a detection data wireless transmission function,
A sensor element;
A control unit configured by a CPU operable in an active mode for performing a normal operation and a sleep mode capable of executing only a timer function;
A data collection unit for collecting the output of the sensor element as detection data;
A wireless communication unit for wirelessly transmitting the collected detection data;
A clock unit for supplying current time information to the control unit,
The CPU can operate at a plurality of clock frequencies having different speeds in the active mode ,
The controller is
Operating the CPU at the lowest clock frequency in the active mode ;
(A ′) a process of acquiring the current time from the clock unit;
(B ′) a process of determining whether or not the time difference from the acquired current time to the specified target time is close to the target time based on whether or not a time difference from the acquired current time is equal to or less than a predetermined lower limit value;
(C ′) If it is determined in the process (b ′) that the target time is not close, the CPU is switched to the sleep mode, and the target time is determined in the process (b ′). And the operation clock of the CPU is not the fastest clock frequency, the operation clock of the CPU in the active mode is switched to a higher clock frequency and the processing (b ′ ) To set the value of the predetermined lower limit value to a value smaller than the current value, and repeat the processes (a ′) to (c ′),
When the operation clock of the CPU is the fastest clock frequency, the current time acquired from the clock unit after the determination of being close to the target time in the process (b ′) is the target time. the detected data by the data collecting section taken Once turned, the detection data collected you and to execute a process of transmitting by the radio communication unit.

  In this way, when the time to the target time is long, the time accuracy of the timer function in the sleep mode is poor, but the CPU is operated with a low-speed clock that consumes less power. Therefore, the power can be further reduced without sacrificing the time accuracy of data detection.

In the present invention, the control unit may add the data collection time to the detection data and transmit the detection data by the wireless communication unit when performing the process of transmitting the detection data by the wireless communication unit. Good. In this way, it is possible to match the time axes of the detection data collected from the plurality of sensor devices based on the collection time added to the detection data, and high-accuracy synchronization can be obtained.

  The sensor device of the present invention further includes a memory accessible by the CPU, the detection data collected by the data collection unit is stored in the memory, and the detection data stored in the memory is stored in the wireless communication unit. May be transmitted wirelessly.

  In this case, the control unit may cause the wireless communication unit to transmit the detection data each time the detection data is stored in the memory, and whether or not data transmission by the wireless communication unit is possible. If the transmission is possible, the detection data stored in the memory may be transmitted by the wireless communication unit in a first-in first-out (FIFO) system. In the latter case, data collection is continued even when data transmission is impossible, and data stored in the memory can be transmitted when data transmission becomes possible.

  The memory stores an operation control table in which a time at which the sensor device should collect detection data from the sensor element is set, and the control unit stores the time recorded in the operation control table. The target time may be set.

  The data sampling unit may AD-convert an output signal of the sensor element and supply the detection data to the CPU, and the CPU may write the detection data into the memory. Alternatively, the data sampling may be performed. The unit may AD-convert the output signal of the sensor element and collect it as the detection data, and the AD-converted detection data may be stored in the memory by a DMA function.

  In the present invention, the sensor device operates in a data detection mode in which detection data from the sensor element is transmitted and a data transfer mode in which detection data transmitted from another sensor device is transferred to another sensor device. It may be possible. In this way, when a plurality of sensor devices are networked, the sensor device can function as a data relay device.

In this case, the memory stores an operation control table in which designation of whether the sensor device should operate in the data detection mode or the data transfer mode and the operation time is set. The control unit executes the processes (a) to ( c ) when the data detection mode is designated with the operation time stored in the operation control table as the target time, and the data transfer mode is If specified, in the process of (d), instead of collecting and transmitting detection data, the wireless communication unit receives detection data from another sensor device and receives the detection data. It may be transferred to a designated destination.

  Thus, in the sensor system configured to include a plurality of sensor devices operable in the data detection mode and the data transfer mode, the plurality of sensor devices are divided into a plurality of clusters, and each cluster includes the same cluster. A cluster head having a function of transferring detection data transmitted from the sensor device in the cluster is provided, and the detection data by each sensor device belonging to each cluster is transmitted via other sensor devices in the same cluster or directly The data may be transmitted to the cluster head of the same cluster and transferred to a predetermined processing apparatus via the cluster head.

  Moreover, the sensor apparatus of this invention is good also as providing a battery as a power supply, and is good also as a battery being a rechargeable battery or a fuel cell in that case.

The present invention also provides a control unit including a sensor element, a CPU operable in an active mode for performing normal operation and a sleep mode capable of executing only a timer function, and an output of the sensor element is collected as detection data. An operation method of a sensor device having a wireless data transmission function, comprising: a data collection unit; a wireless communication unit that wirelessly transmits the collected detection data; and a clock unit that supplies current time information to the control unit. ,
The controller is in the active mode of the CPU,
(A) obtaining a current time from the clock unit;
(B) determining whether or not the vehicle has approached the designated target time based on the acquired current time;
(C) In step (b), when the it is determined not to be close to the target time, switch the CPU into the sleep mode, before Symbol step (b), in proximity to the target time Collecting the detection data by the data collection unit when the current time acquired from the clock unit becomes the target time after being determined to be, and transmitting the collected detection data by the wireless communication unit. Run ,
When a predetermined sleep time elapses in the sleep mode of the CPU, the CPU is switched to the active mode, and then the processes of steps (a) to (c) are repeated .

  ADVANTAGE OF THE INVENTION According to this invention, in the sensor apparatus which has the wireless transmission function of detection data, it becomes possible to extract | collect detection data with high time precision, restraining power consumption low.

  Hereinafter, a sensor device according to an embodiment of the present invention will be described in detail. In the present embodiment, the sensor device of the present invention transmits an operation mode (hereinafter referred to as a data detection mode) in which detection data from the sensor is transmitted wirelessly, and data transmitted from another sensor device is transmitted to another sensor device, etc. It is assumed that it can operate in a mode for transferring data (hereinafter referred to as a data transfer mode).

  FIG. 1 is an overall configuration diagram illustrating an example of a system configured by forming a plurality of sensor devices 10 of this embodiment into a network. In the example shown in the figure, a plurality of sensor devices 10 are clustered into clusters A, B, C, etc., and a cluster head 1 (1A, 1B, 1C,...) Is provided for each cluster. The cluster head 1 has a function of detecting data transmitted from the sensor device 10 and other cluster heads 1. That is, the sensor device 10 does not have the data detection mode, and operates only in the data transfer mode.

  The sensor device 10 belonging to each cluster wirelessly transmits the detection data to the corresponding cluster head 1 via another sensor device 10 belonging to the same cluster or directly. The cluster head 1 transmits the detection data transmitted from each sensor device 10 in the cluster to the gateway 3 connected to the processing computer 2 via another cluster head 1 or directly. For example, in FIG. 1, the detection data by the sensor device 10a belonging to the cluster B is transferred to the cluster head 1B via the sensor device 10b, and further transferred to the gateway 3 via any one of the cluster heads 1C to 1E. Captured from the gateway 3 into the processing computer 2.

  Each sensor device 10 and each cluster head 1 is given a unique identification ID, and the data transmission path from each sensor device 10 to the gateway 3 is an operation control table (for each sensor device 10 and each cluster head 1). Set to be described later).

  FIG. 2 is a block diagram of the sensor device 10 according to the present embodiment. As shown in the figure, the sensor device 10 includes a detection unit 20, a data collection unit 22, a CPU 24, a high-precision clock unit 26, a memory 28, a wireless communication unit 30, a low-speed clock generation unit 32, a high-speed clock generation unit 34, and a battery. 36.

  The detection unit 20 is configured by one or a plurality of sensor elements 21. The sensor element 21 is a sensor element that detects a physical quantity that changes continuously, such as acceleration, and outputs an analog signal corresponding to the physical quantity to the data collection unit 22.

  The data collection unit 22 appropriately amplifies the analog signal output from each sensor element 21 of the detection unit 20 and converts it into digital data, and collects this digital data as detection data. The collected detection data is stored in the memory 28 by the CPU 24 or by the DMA function.

  The wireless communication unit 30 wirelessly transmits the detection data stored in the memory 28 to a designated transmission destination in response to a command from the CPU 24.

  The CPU 24 controls each unit of the sensor device 10 and performs control such as reading of detection data from the data collection unit 22, transmission of detection data by the wireless communication unit 30, and data transfer from other sensor devices 10. Note that the CPU 24 can operate in an active mode in which normal operation is performed and a sleep mode in which only the timer function is effective and which operates at extremely low power.

  The high-precision timepiece unit 26 is configured by a high-precision timepiece such as a radio wave timepiece, GPS, or quartz timepiece, and supplies current time information to the CPU 24.

  The low-speed clock generator 32 and the high-speed clock generator 34 generate an operation clock for the CPU 24. Which clock of the low-speed clock generator 32 and the high-speed clock generator 34 is operated by the CPU 24 can be set by the CPU 24 executing a clock selection command.

  The battery 36 supplies power to each part of the sensor device 10. Typically, a rechargeable battery is used, but a fuel cell may be used. The battery may be a built-in battery or an external battery.

  FIG. 3 is an example of the operation control table 50 for setting the operation of the sensor device 10. The operation control table 50 is stored in the memory 28, and the contents can be set by the user through an appropriate user interface.

  As shown in FIG. 3, the operation control table 50 stores the operation time and operation content of each operation to be performed by the sensor device 10. Specifically, the operation control table 50 includes an operation time column 52, an operation designation column 54, a transmission source column 56, a transmission destination column 58, and a detection operation detail column 60. In the operation time column 52, a time at which the sensor device 10 should start operation is set, and in the operation designation column 54, the operation classification of the sensor device 10 (operation in any one of the data detection mode and the data transfer mode described above is performed). Is set). In the transmission source column 56, when the data transfer mode is set in the operation designation column 54, the ID of the sensor device 10 or the gateway 1 that is the transmission source of the data to be transferred is set. On the other hand, in the transmission destination column 58, the ID of the sensor device 10 or the gateway 1 that is the transmission destination of data is set. In the detection operation detail column 60, details of the detection operation in the detection function are set. For example, among the plurality of sensor elements 21 included in the detection unit 20, designation of a sensor from which data is to be collected, sampling frequency, and data byte Number etc. are set.

  In the example of FIG. 3, the detection data from the sensors # 1, # 2, and # 3 is collected at 11:55:00 in the data detection mode and transmitted to the sensor device 10 or the cluster head 1 with ID = 1123, The data transmitted from the sensor device 10 with ID = 1048 in the data transfer mode at 11:56:30 is set to be transferred to the sensor device 10 with ID = 1123 or the cluster head 1.

  Each operation to be performed by the sensor device 10 set in the operation control table 50 is hereinafter referred to as an operation job. That is, in the example of FIG. 3, an operation job in the data detection mode to be executed at 11:55:00 and an operation job in the data transfer mode to be executed at 11:56:30 are set.

  Hereinafter, processing executed by the CPU 24 of the sensor device 10 in the present embodiment will be described. As described above, the CPU 24 can operate in the active mode and the sleep mode. In this embodiment, the CPU 24 uses the sleep mode in which the power consumption of the CPU 24 is small and suppresses power consumption, and is provided from the high-precision clock unit 26. Detection data can be collected with high time accuracy based on the highly accurate time information. The CPU 24 sets the sleep time in the active mode and executes the instruction to shift to the sleep mode, thereby switching to the sleep mode. During the sleep mode, the CPU 24 counts the time by the timer function, and the set sleep time is set. After the elapse of time, the sleep mode can be switched to the active mode.

  4 and 5 are flowcharts showing the flow of a processing routine executed by the CPU 24 in the present embodiment. This processing routine is started when the CPU 24 is switched from the sleep mode to the active mode in S100 of FIG. As can be seen from the following description, when switching to the active mode in S100, the CPU 24 operates with a low-speed clock. Note that the flowcharts shown in FIGS. 4 and 5 show processing when the sensor device 10 executes an operation job in the sensor detection mode.

  In S100 shown in FIG. 4, when the CPU 24 switches to the active mode, first, in S102, the current time Tc is read from the high precision clock unit 26. Next, in S104, a time difference ΔT = To−Tc between the operation time of the operation job to be executed next (hereinafter referred to as target time To) and the current time Tc is calculated. Then, in S106, it is determined whether or not the time difference ΔT is equal to or smaller than a predetermined lower limit value TL corresponding to the low-speed clock mode.

  If ΔT ≦ TL is not established in S106, it is determined that the target time To is not approached, and the sleep time Ts is calculated by Ts = ΔT × C (where C is a constant smaller than 1) in S108. . In S110, the sleep time Ts is set, the CPU 24 is switched to the sleep mode, and the sleep timer starts counting up. Thereafter, the sleep mode is maintained until the sleep time Ts elapses in S112, and when the sleep time Ts elapses, the mode is switched to the active mode in S100 and the process returns to S102.

  On the other hand, if ΔT ≦ TL is established in S106, it is determined that the target time To has been approached, and the operation clock of the CPU 24 is switched to the high-speed clock of the high-speed clock generation unit 34 in S120. In step S122, the current time Tc is read from the high-precision clock unit 26. In step S124, a time difference ΔT between the target time To and the current time Tc is calculated. In step S126, the time difference ΔT is equal to or less than a predetermined lower limit TH corresponding to the high-speed clock. It is determined whether or not. Note that the value of the lower limit value TH is set to a value smaller than the lower limit value TL for the low-speed clock.

  If ΔT ≦ TH is not satisfied in S126, it is determined that the target time To is not approached, and similarly to S108 to S112, the sleep time Ts = ΔT × C is calculated in S128, and the sleep time Ts in S130. Is set and the CPU 24 is switched to the sleep mode. When the sleep time Ts elapses in S132, the CPU 24 switches to the active mode in S134, and then returns to S122.

  On the other hand, when ΔT ≦ TH is established in S126, it is determined that the target time To has been approached, and in S140 of FIG. 5, the current time Tc is read from the high-precision clock unit 26, and in S142, the target time To and the current time are read. A time difference ΔT = To−Tc with respect to Tc is calculated, and it is determined whether or not the time difference ΔT has become 0 or less in S144. As a result, if ΔT ≦ 0 is not established, the process returns to S140. On the other hand, if ΔT ≦ 0 holds, the target time To has been reached. In this case, in S146, the detection data of the sensor element 21 (if the sensor number is specified in the detection operation detail column 60 of the operation control table 50, corresponding to the sensor element 21) is fetched from the data collection unit 22. Stored in the memory 28. At this time, the current time Tc is stored as the data collection time Ta along with the detection data. Next, in S 148, the detection data stored in the memory 28 is wirelessly transmitted by the wireless communication unit 30 to the sensor device 10 or the cluster head 1 having the ID set in the transmission destination column 58 of the operation control table 50. Details of this transmission operation will be described later.

  In S150, it is determined whether or not the detection data transmission in S148 has been performed normally. Specifically, each sensor device 10 and each cluster head 1 is configured to return a reception confirmation signal when receiving data addressed to itself, and whether or not this reception confirmation signal has been returned in S150. Based on the above, it is determined whether or not the data transmission is normally performed. As a result, if data transmission is normally performed, the process proceeds to S160. On the other hand, if the data transmission is not normally performed, the data is retransmitted until the predetermined number of times is reached in S152, and the current routine is terminated when the data transmission is normally performed. If data transmission is not performed normally even after a predetermined number of retransmissions, appropriate error processing such as error display is performed in S154, and the process proceeds to S160. However, as will be described later, if transmission is not successful even after a predetermined number of re-transmissions in S152, the collected detection data is held in the memory 28, and when the data transmission becomes possible, the held detection data May be transmitted in a batch.

  In S160, the operation job to be executed next is read from the operation control table 50, and the operation time is set as a new target time To. In S162, the current time Tc is acquired from the high-precision clock unit 26. In S164, the time difference To-Tc is calculated. In S166, the operation clock of the CPU 24 is switched to the low-speed clock, and the process returns to S108 in FIG. As a result, the CPU 24 is switched to the sleep mode, and thereafter, the same processing as described above is performed for the next operation job.

  4 and 5 show the processing when the sensor device 10 executes the operation job in the data detection mode. However, for the operation job in the data transfer mode, instead of the detection data capturing processing in S146. In addition, the data may be received from the transmission source specified in the transmission source column 56 of the operation control table 50, and the data may be transmitted to the transfer destination in S148.

  Here, the detection data transmission processing in S148 will be described. FIG. 6 is a diagram illustrating a configuration of data transmitted by the wireless communication unit 30 of the sensor device 10 in the present embodiment. As shown in the figure, the data is composed of a data main body portion 60 in which data detected by the detection portion 20 is stored and a header portion 70. The header unit 70 includes an ID (sender ID) 72 of the sensor device 10 that has transmitted the data, an ID (detector ID) 74 of the sensor device 10 that has detected the detection data stored in the data body unit 60, and detection data. Detection time 76.

  When the sensor device 10 operates in the data detection mode, when transmitting detection data in S148 of FIG. 5, the detection data captured in S146 is stored in the data body 60, and the detection time Ta is stored as the detection time 76. The wireless communication unit 30 transmits data stored with its own ID as the sender ID 72 and the detector ID 74. Further, when the sensor device 10 operates in the data transfer mode, the sender ID 72 of the data received from the other sensor devices 10 is rewritten to its own ID and transmitted.

  According to the routines shown in FIGS. 4 and 5, first, the CPU 24 is operated with a low-speed clock, and switching to the sleep mode is performed until the time difference between the target time and the current time is equal to or lower than the lower limit value TL (yes in S106). (S110) and switching to the active mode after the sleep time Ts has elapsed (S114) are repeated. At that time, the sleep time Ts is set to a value obtained by multiplying the time difference ΔT between the target time and the current time by a predetermined value C smaller than 1 (S108), so that the sleep time Ts becomes gradually shorter as the target time To approaches. Become.

  When the time difference ΔT is less than or equal to the lower limit value TL, the CPU 24 is switched to the high speed clock (S120), and switching to the sleep mode is performed (S130) until the time difference ΔT becomes the lower limit value TH0 or less corresponding to the high speed clock (S130). ) And switching to the active mode after the sleep time Ts has elapsed (S134). Then, when the time difference ΔT becomes equal to or lower than the lower limit value TH, the current time is acquired from the high-accuracy clock unit 26 as the always active mode, and when the target time To is reached, the detection data is captured and transmitted. Do.

  As described above, in the present embodiment, when the time to the target time To is long, the CPU 24 is basically operated in the sleep mode, and sometimes the active mode is switched to the high-precision current time from the high-precision clock unit 26. And the time difference ΔT with respect to the target time is determined. For this reason, most of the time until the target time To is reached, the CPU 24 operates in the sleep mode in which the power consumption is extremely low, so that the power consumption of the sensor device 10 can be kept small.

  In addition, as described above, by setting the sleep time Ts to be shorter as it approaches the target time To, the target time To is reached during the operation in the sleep mode while ensuring the operation time in the sleep mode as long as possible. It is possible to reliably collect data at the target time To.

  Further, while the time to the target time To is long (while the time difference ΔT is larger than the lower limit TL), there is no problem even if the sleep time count accuracy is low, so by operating with a low speed clock with low power consumption, Further power saving can be achieved. When the time difference ΔT falls below the lower limit value TL, the clock is switched to a high-speed clock, and when the time difference ΔT falls below the lower limit value TH, the active clock mode is always set to obtain a high precision time from the high precision clock unit 26. The detection data can be read by accurately detecting that the target time To has been reached while suppressing power consumption as much as possible.

  In the above embodiment, the CPU 24 operates at two clock speeds of the low speed clock and the high speed clock. However, if the time difference ΔT is determined to be equal to or lower than the lower limit value in S126 without switching the clock, It is also possible to immediately proceed to the processing after S140. On the other hand, the CPU 24 may operate at a clock speed of three or more stages. In this case, the routine shown in FIGS. 4 and 5 is started from the lowest clock speed, and the first stage when the time difference ΔT falls below the lower limit value. Switching to a high-speed clock, and when the time difference ΔT is less than or equal to the lower limit value with the fastest clock, the processing after S140 in FIG. 5 may be executed.

  As described above, according to the present embodiment, it is possible to collect data detected by the detection unit 20 at a highly accurate timing with respect to the target time To, while saving power of the sensor device 10. And since the duration of the battery 36 also becomes long because the power consumption of the sensor device 10 becomes small, when using a battery that cannot be charged as the battery 36, the replacement frequency of the battery can be suppressed. When used, the charging frequency can be suppressed, and when the fuel cell is used, the replenishment frequency of the fuel can be suppressed. Thus, the entire system can be operated efficiently.

  In particular, in the case of a signal whose detection target changes rapidly and continuously like an acceleration sensor, it is necessary to collect a large amount of data at a high sampling frequency in order to reproduce the waveform. Since it takes a long time and power consumption increases accordingly, there is a great demand for power saving. Therefore, the sensor device of the present invention is extremely effective in the case of a sensor that detects a physical quantity that changes continuously at high speed, such as an acceleration sensor.

  Further, since each sensor device 10 can collect detection data with high time accuracy, even when a plurality of sensor devices 10 are provided as shown in FIG. 1, these sensor devices 10 can be operated in synchronization with each other. it can. Even when the sensor devices 10 cannot be completely synchronized, the high-accuracy time acquired by the high-precision clock unit 26 in each sensor device 10 is detected as detection time 76 as shown in FIG. Therefore, after the computer 2 reads data from the plurality of sensor devices 10, it is possible to obtain highly accurate synchronism by aligning the time axes of the data.

  Further, as shown in FIG. 1, a plurality of sensor devices 10 are divided into clusters, the sensor devices 10 in each cluster 1 are operated at the same timing, and the sensor devices 10 in other clusters that do not need to be operated simultaneously are Can be paused. That is, since only the sensor devices 10 belonging to the necessary clusters can be activated in the active mode and the other sensor devices 10 can be maintained in the sleep mode, the power consumption of the entire system can be suppressed.

  Further, each sensor device 10 has a function of operating in the data detection mode and the data transfer mode, and the operation mode and the operation time can be individually set for each operation job. It is possible to transmit to the computer 12 by activating only the minimum necessary sensor device 10 and cluster head 1. For example, in FIG. 1, if the detection data of the sensor device 10a is transmitted through the route of the sensor device 10b → the cluster head 1B → the cluster head 1D → the gateway 3, the sensor device 10b, the cluster head 1B, If only the cluster head 1D is activated in the active mode, the detection data of the sensor device 10a can be transmitted to the computer 2 via the gateway 3, and the other sensor devices 10 and the like may remain in the sleep mode. Overall power consumption can be reduced. Specifically, the operation job of each device is set so that the sensor device 10a operates in the data detection mode, the sensor device 10b, the cluster head 1B, and the cluster head 1D operate in the data transfer mode, and the other devices are suspended. State.

  In this case, since data transmission takes time, it is possible to further reduce power consumption by setting the operation time of each device by shifting the time in consideration of the data transmission time. For example, in the above example, the operation times of the sensor device 10b, the cluster head 1B, and the cluster head 1E are sequentially delayed by a predetermined time according to the data transfer time with respect to the operation time of the sensor device 10a in the data detection mode. . Thereby, the sensor device 10b, the cluster head 1B, and the cluster head 1E can be set to the sleep mode until just before the timing at which the data transfer operation is required. That is, in this embodiment, since the sensor device 10 and the cluster head 1 can be operated based on the high-precision time information by the high-precision clock unit 26, the operation time of each sensor device 10 and the cluster head 1 is transmitted as data. It can be set in detail in consideration of the time, and thereby further power saving can be achieved.

  In the above description, the sensor device 10 transmits the detection data every time it collects the detection data (hereinafter, such a transmission method is referred to as occasional transmission). (Hereinafter, such a transmission method is referred to as batch transmission).

  FIG. 7 is a diagram illustrating the timing of each operation of data collection, memory access, and data transmission for occasional transmission and batch transmission. As shown in (a) in the figure, the transmission operation is performed every time the detection data is collected and written in the memory in the occasional transmission. However, in the collective transmission, the data is held in the memory 28 as shown in the figure (b). Since the detected data for a plurality of times are transmitted at once, the number of transmissions is reduced. In the data transmission, in addition to the data having the configuration shown in FIG. Therefore, in the case of batch transmission, the amount of such accompanying packets is reduced compared to the case of transmission at any time, and the total transmission time can be shortened. As a result, the power consumption can be further suppressed. An effect is obtained.

  According to the batch transmission described above, the following effects can also be obtained. In the case of the configuration divided into clusters as shown in FIG. 1, according to batch transmission, it is possible to collect detection data for a plurality of times in another cluster while collecting detection data repeatedly in one cluster. is there. For example, in FIG. 1, it is assumed that the detection data in the cluster A is set to be transmitted via the cluster head 1B of the cluster B. In this case, since the cluster head 1B is occupied while the cluster B is transmitting data, the detection data of the cluster A cannot be transmitted. However, according to batch transmission, data is being transmitted in the cluster B. Each sensor device 10 of the cluster A holds the detection data in the memory 28, and when the cluster head 1B is released after the data transmission of the cluster B is completed, the detection data held in the memory 28 is collectively collected. Can be sent. In this way, by performing batch transmission, it is possible to set the collection time of detection data freely and accurately in each cluster without being affected by the operation state of other clusters.

  FIG. 8 shows an example of a data storage method in the memory 28 for realizing the batch transmission described above. In the example shown in the figure, the memory 28 is configured as a FIFO (First In First Out) memory, and the collected detection data D1, D2, D3,... Dn are sequentially stored in the memory 28, and data transmission becomes possible. At the same timing, the detection data stored in advance is transmitted sequentially.

  Note that the CPU 24 may control whether to perform transmission at any time or to perform batch transmission according to the situation at that time. Specifically, first, the CPU 24 determines whether or not data transmission by the wireless communication unit 30 is possible. This determination can be made, for example, based on whether or not dummy data is transmitted to the data transmission destination and a reception confirmation signal is returned. As a result, if data transmission is possible, detection data is transmitted (as needed). On the other hand, if data transmission is impossible, the detection data is sequentially stored in the memory 28 as shown in FIG. When the data transmission becomes possible, the data stored in the memory 28 is transmitted (batch transmission) by the FIFO method. That is, in the flowchart of FIG. 5, if normal transmission is not possible even if a predetermined number of retransmissions are attempted in S152, error detection is not performed in S154, but the detected data is held in the memory 28, and data transmission becomes possible. Then, batch transmission can be realized by transmitting the stored data in batch.

  Note that when a radio clock or GPS is used as the high-precision clock unit 26, accurate time can always be detected without calibration, but depending on the installation environment of the sensor device 10, radio wave clocks and GPS radio waves can be received. In some cases, a quartz watch must be used. In that case, at an appropriate timing, time information for time calibration is supplied to each sensor device 10 from the outside, and using the data transfer function of the sensor device 10, a time calibration command is transmitted to all the sensor devices all at once, In response to the time calibration command, each sensor device 10 may calibrate its own quartz clock based on time information supplied from the outside.

1 is an overall configuration diagram illustrating an example of a system configured by forming a plurality of sensor devices according to an embodiment of the present invention into a network. It is a block block diagram of the sensor apparatus 10 concerning this embodiment. It is an example of the operation control table 50 for setting operation | movement of the sensor apparatus of this embodiment. It is a flowchart (the 1) which shows the flow of the processing routine which CPU which a sensor apparatus provides in this embodiment performs. It is a flowchart (the 2) which shows the flow of the processing routine which CPU which a sensor apparatus provides in this embodiment performs. It is a figure which shows the structure of the data transmitted from a sensor apparatus in this embodiment. It is a time chart which shows the operation timing of a sensor apparatus in this embodiment about the case of transmission at any time and collective transmission. It is a figure which shows an example of the data storage method to the memory for implement | achieving collective transmission.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Sensor apparatus 20 Detection part 21 Sensor element 22 Data collection part 24 CPU 26 High precision clock part 28 Memory 30 Wireless communication part 32 Low speed clock generation part 34 High speed clock generation part 36 Battery 50 Operation control table 52 Operation time column 54 Operation specification column 56 Transmission source column 58 Transmission destination column 60 Detailed detection operation column

Claims (17)

A sensor device having a function of wirelessly transmitting detection data,
A sensor element;
A control unit configured by a CPU operable in an active mode for performing a normal operation and a sleep mode capable of executing only a timer function;
A data collection unit for collecting the output of the sensor element as detection data;
A wireless communication unit for wirelessly transmitting the collected detection data;
A clock unit for supplying current time information to the control unit,
The controller is
In the active mode of the CPU,
(A) a process of acquiring the current time from the clock unit;
(B) a process of determining whether or not the acquired target time is close to the specified target time;
(C) the processing of the (b), when the said is determined not to be close to the target time, switch the CPU into the sleep mode, in the processing of pre-Symbol (b), close to the target time after it is determined to be, the process of the current time acquired from the clock unit is the collected detection data by the data collecting section Once at the target time, and transmits the detected data collected by the wireless communication unit Run ,
A sensor device characterized by repeating the processes (a) to (c) after switching the CPU to the active mode when a predetermined sleep time elapses in the sleep mode of the CPU . In the process of (c), the control unit calculates a time difference from the acquired current time to the target time when it is determined in the process of (b) that it is not close to the target time. The sensor device according to claim 1, wherein the predetermined sleep time is set to a smaller value as the time difference is smaller. Wherein, prior Symbol sensor device according to claim 2, characterized in that a value obtained by multiplying a constant smaller than 1 on the time difference as the predetermined sleep time. A sensor device having a function of wirelessly transmitting detection data,
A sensor element;
A control unit configured by a CPU operable in an active mode for performing a normal operation and a sleep mode capable of executing only a timer function;
A data collection unit for collecting the output of the sensor element as detection data;
A wireless communication unit for wirelessly transmitting the collected detection data;
A clock unit for supplying current time information to the control unit,
The CPU can operate at a plurality of clock frequencies having different speeds in the active mode ,
The controller is
Operating the CPU at the lowest clock frequency in the active mode ;
(A ′) a process of acquiring the current time from the clock unit;
(B ′) a process of determining whether or not the time difference from the acquired current time to the specified target time is close to the target time based on whether or not a time difference from the acquired current time is equal to or less than a predetermined lower limit value;
(C ′) If it is determined in the process (b ′) that the target time is not close, the CPU is switched to the sleep mode, and the target time is determined in the process (b ′). And the operation clock of the CPU is not the fastest clock frequency, the operation clock of the CPU in the active mode is switched to a higher clock frequency and the processing (b ′ ) To set the value of the predetermined lower limit value to a value smaller than the current value, and repeat the processes (a ′) to (c ′),
When the operation clock of the CPU is the fastest clock frequency, the current time acquired from the clock unit after the determination of being close to the target time in the process (b ′) is the target time. the data collecting section by collected detection data, characteristics and to Rousset capacitors apparatus to perform a process of transmitting the detected data collected by the wireless communication unit When turned. The control unit, when performing a process of transmitting the detection data by the wireless communication unit , adds a data collection time to the detection data and transmits the detection data by the wireless communication unit. 4. The sensor device according to claim 1. A memory accessible by the CPU;
The detection data collected by the data collection unit is stored in the memory,
The wireless communication unit sensor device according to any one of claims 1-3, characterized in that wirelessly transmits the detection data stored in the memory.   The sensor device according to claim 6, wherein the control unit transmits the detection data by the wireless communication unit every time the detection data is stored in the memory.   The control unit determines whether or not data transmission by the wireless communication unit is possible. If transmission is possible, the control unit transmits the detection data stored in the memory by the first-in first-out method. The sensor device according to claim 6.   The memory stores an operation control table in which a time at which the sensor device should collect detection data from the sensor element is set, and the control unit uses the time recorded in the operation control table as the target time. The sensor device according to any one of claims 6 to 8, wherein:   The data collection unit performs AD conversion on an output signal of the sensor element and supplies the detection data to the CPU as the detection data, and the CPU writes the detection data into the memory. The sensor device according to any one of the preceding claims.   10. The data sampling unit AD-converts an output signal of the sensor element into the detection data, and the AD-converted detection data is stored in the memory by a DMA function. The sensor device according to any one of the preceding claims.   The sensor device is operable in a data detection mode for transmitting detection data from the sensor element and a data transfer mode for transferring detection data transmitted from another sensor device to another sensor device. The sensor device according to any one of claims 1 to 5. The sensor device is operable in a data detection mode for transmitting detection data from the sensor element and a data transfer mode for transferring detection data transmitted from another sensor device to another sensor device,
The memory stores an operation control table in which designation of whether the sensor device should operate in the data detection mode or the data transfer mode and the operation time is set. When the data detection mode is specified with the operation time stored in the operation control table as the target time, the processes (a) to ( c ) are executed, and the data transfer mode is specified. In the case of (c), in place of collecting and transmitting detection data, the wireless communication unit receives detection data from another sensor device and designates the detection data. It transfers to a transmission destination, The sensor apparatus in any one of Claims 6-11 characterized by the above-mentioned.   The sensor device according to claim 1, further comprising a battery as a power source.   The sensor device according to claim 14, wherein the battery is a rechargeable battery or a fuel cell. A sensor element;
A control unit composed of a CPU operable in an active mode for performing normal operation and a sleep mode capable of executing only a timer function;
A data collection unit for collecting the output of the sensor element as detection data;
A wireless communication unit for wirelessly transmitting the collected detection data;
An operation method of a sensor device having a wireless data transmission function, comprising: a clock unit that supplies current time information to the control unit;
The controller is in the active mode of the CPU,
(A) obtaining a current time from the clock unit;
(B) determining whether or not the vehicle has approached the designated target time based on the acquired current time;
(C) In step (b), when the it is determined not to be close to the target time, switch the CPU into the sleep mode, before Symbol step (b), in proximity to the target time Collecting the detection data by the data collection unit when the current time acquired from the clock unit becomes the target time after being determined to be, and transmitting the collected detection data by the wireless communication unit. Run ,
A method of operating a sensor device, comprising: repeating the processing of steps (a) to (c) after switching the CPU to the active mode when a predetermined sleep time elapses in the sleep mode of the CPU . A sensor system comprising a plurality of sensor devices according to claim 12 or 13,
The plurality of sensor devices are divided into a plurality of clusters,
Each cluster is provided with a cluster head having a function of transferring detection data transmitted from sensor devices in the same cluster,
Data detected by each sensor device belonging to each cluster is transmitted to another cluster device in the same cluster or directly to the cluster head of the same cluster, and transferred to a predetermined processing device via this cluster head. A sensor system.