Communication system and remote control terminal device

Abstract

To solve the problem of a shortage of the number of communication pairs of a control in a radio control by a remote controller, in addition, a cost and a work period because a radio engineer has to go to the site for performing an inspection of a radio frequency band before and after installation, determines a frequency and an installation location, and adjusts an antenna.SOLUTION: In a communication system 1 of the present invention, a communication pair 10 (P1 to P10) can share a communication channel #1. Since there is 16 communication channels, a pair of 160 communication channels can be used at the same location. A remote control terminal device 10 contained in each of the communication pairs P1 to P10 intermittently (0.8 ms) and periodically (20 ms) transmits a signal. Since a collision of the signal is avoided by a signal transmission for applying an off-set of the random number to a predetermined period, the signal is transmitted to a control device in a constant ratio while generating the signal collision between the communication pairs 10. The pair of 160 which is four times as compared with a conventional art can be used, and an adjustment by an engineer is not required.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a communication system and a remote control terminal device. [Background technology]

[0002] In recent years, wireless communication technologies such as wireless LANs (Local Area Networks) have rapidly become widespread (see, for example, Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-222608 A [Patent Document 2] JP 2009-182644 A [Patent Document 3] JP 2012-147324 A [Patent Document 4] JP 2020-129733 A Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, in factories and the like, it has been common to remotely control equipment such as cranes using remote controllers (hereinafter, remote controls), and communication for this remote control has been realized mainly by wired communication, which is considered to be highly reliable, because safety is emphasized. Ensuring safety is especially important in control involving power. Since wireless communication has the advantage of eliminating the need for communication lines and power lines connecting the equipment and the remote control, it is conceivable to replace wired communication with wireless communication for remote control of equipment in factories and the like. When changing remote control using a remote control from wired to wireless, ensuring safety is considered the most important. It is necessary to satisfy the requirement that a rapid response can be reliably executed when an abnormality occurs, and in order to achieve this, it is necessary to ensure that communication for remote control can be performed reliably, so it is considered best to assign a dedicated communication channel (specific frequency band) to each pair of a remote control and the equipment to be operated, and to occupy the communication channel for communication for remote control of the equipment. On the other hand, in the method of assigning a dedicated communication channel to each pair of remote control and target device, the conventional specified low power wireless communication method (wireless equipment with 400MHz band occupied frequency bandwidth of 8.5kHz or less) has 46 communication channels, so the upper limit is 46 devices in the system, and the conventional specified low power wireless communication method (wireless equipment with 1200MHz band occupied frequency bandwidth of 16kHz or less) has 40 communication channels, so the upper limit is 40 devices in the system. Since the number of channels is limited, there is a concern of a shortage of communication channels. Not only this, but there is a safety risk of malfunction due to interference with the same frequency or adjacent channels with other communications, or spurious interference, which will further lead to a shortage of communication channels. Furthermore, in order to prevent interference and disturbances that threaten safety, radio engineers must go to the site to investigate available radio frequency bands, determine the number of devices that can be installed, determine the installation locations, adjust antennas, etc. With conventional specific low-power wireless communication methods, if a channel is already in use, that channel cannot be used, and even if it is not the same channel, if an adjacent channel is in use first, interference will occur, making on-site investigations essential.The amount of work required for this, including investigating any problems that arise after installation, cannot be ignored.

[0005] The present invention aims to ensure safety in wireless communication control and achieve rapid system operation, thereby providing a technology that enables rapid response to the occurrence of abnormalities, prevents system malfunctions due to interference with other communications, and eliminates the need for engineers to make on-site adjustments during installation, thereby achieving wireless communication that allows remote operation of equipment using a remote controller without monopolizing the communication channel. [Means for solving the problem]

[0006] A communication system according to a first aspect of the present disclosure includes: The system includes N pairs of remote control terminal devices and control devices (N is an integer of 1 or more), Each of the plurality of remote control terminal devices a wireless communication unit that transmits data to a control device paired with the device itself by wireless communication on a predetermined communication channel; The wireless communication device is characterized by having a control unit that adjusts the timing of execution of the wireless communication by the wireless communication unit by adding an offset corresponding to a random number to a timing determined according to a predetermined period.

[0007] A more preferred communication system according to a second aspect is the communication system according to the first aspect, The wireless communication unit included in each of the plurality of remote control terminal devices is performing intermittent periodic transmission (hereinafter referred to as burst transmission) on the communication channel over a predetermined period of time; It is characterized by:

[0008] A further preferred communication system according to a third aspect is the communication system according to the second aspect, When the N control devices detect interference or obstruction in wireless communication with a remote control terminal device paired with the own device, the N control devices transmit a change instruction to the remote control terminal device paired with the own device to instruct the change of the communication channel; the control unit included in each of the N remote control terminal devices changes the communication channel used for transmitting data to the control device paired with the respective remote control terminal devices in response to the change instruction; The present invention may be characterized in that:

[0009] A further preferred communication system according to a fourth aspect is the communication system according to the third aspect, When the N control devices detect interference or disturbance in a communication channel used for wireless communication with a remote control terminal device paired with the control device, the N control devices determine a communication channel that is less susceptible to interference or disturbance by searching for the presence or absence of interference or disturbance for each of a plurality of communication channels different from the communication channel, and transmit a change instruction to the remote control terminal paired with the control device to instruct the control device to change to the determined communication channel. The present invention may be characterized in that:

[0010] A further preferred communication system according to a fifth aspect is the communication system according to the fourth aspect, The control device that has transmitted the change instruction returns a response when it receives data from a remote control terminal paired with the control device through wireless communication on the communication channel that has been instructed to change the communication channel; completing the change of the communication channel when the remote control terminal that has changed the communication channel and transmitted the data in response to the change instruction receives the response; The present invention may be characterized in that:

[0011] A further preferred communication system according to a sixth aspect is the fifth communication system, When the control device that transmitted the change instruction fails to receive data a predetermined number of times from the remote control terminal device paired with the control device itself through wireless communication of the communication channel instructed to be changed, or fails to receive data from the remote control terminal device paired with the control device itself within a predetermined time period after the transmission of the change instruction, the control device returns to the original communication channel and repeats the process of transmitting the communication channel change instruction again a predetermined number of times, and when the communication channel change is not successful even after repeating the process a predetermined number of times, the control device returns to the original communication channel or searches the multiple communication channels again and transmits the change instruction to a different communication channel. The present invention may be characterized in that:

[0012] In addition, a preferred seventh aspect of the present invention provides a communication system according to the second aspect of the present invention, When the N control devices detect interference or disturbance in a communication channel used for wireless communication with a remote control terminal device paired with the own device, the N control devices transmit a change instruction to the remote control terminal device paired with the own device to instruct the change of the communication channel; the control unit included in each of the N remote control terminal devices changes the communication channel used for transmitting data to the control device paired with the respective remote control terminal devices in response to the change instruction; It is characterized by:

[0013] A more preferable communication system according to an eighth aspect is the communication system according to any one of the first to seventh aspects, Each of the N remote control terminal devices is a remote controller for remotely controlling N different operation target devices, and each of the N control devices is included in each of the N operation target devices, Each of the N control devices transmits a response in response to an instruction received from a maintenance terminal that performs remote maintenance of the operation target devices including the control device to a remote control terminal device that is paired with the control device; the control unit in each of the N remote control terminal devices executes a process in response to the response received via the wireless communication unit. The present invention may be characterized in that:

[0014] The remote control terminal device of the present disclosure is a wireless communication unit that transmits data to a control device paired with the device itself by wireless communication on a predetermined communication channel; The wireless communication device further includes a control unit that adjusts a timing of execution of the wireless communication by the wireless communication unit by adding an offset according to a random number to a timing determined according to a predetermined cycle. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram illustrating a configuration example of a communication system 1 according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram showing an example of communication channel allocation in the communication system 1. As shown in FIG. [Diagram 3] FIG. 3 is a diagram showing an example of the configuration of the remote control terminal device 10. As shown in FIG. [Figure 4] FIG. 4 is a diagram showing an example of a format of a communication message transmitted from the remote control terminal device 10 to the control device 20. As shown in FIG. [Diagram 5] FIG. 5 is a diagram for explaining burst transmission executed by the remote control terminal device 10. As shown in FIG. [Figure 6] FIG. 6 is a diagram showing an example of an execution period of burst transmission by the remote control terminal device 10. As shown in FIG. [Figure 7] FIG. 7 is a graph showing the relationship between the transmission interval T2 (ms) and the time (ms) at which the call loss rate standard is cleared. [Figure 8] FIG. 8 is a flow chart showing the flow of processes after burst transmission that the control unit 110 of the remote control terminal device 10 executes in accordance with a control program. [Figure 9] FIG. 9 is a flowchart showing an example of the operation of the control device 20 when disturbance or interference is detected in a communication channel used for wireless communication with the remote control terminal device 10. In FIG. [Figure 10] FIG. 10 is a diagram showing actual measurement values ​​of the D / U ratio and the call loss rate between terminals when collision occurs over the air in the communication system 1. In FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that numerical values ​​and the like in the embodiments are merely examples and are not intended to limit the present disclosure.

[0017] <1. Embodiment> FIG. 1 is a diagram illustrating a configuration example of a communication system 1 according to an embodiment of the present disclosure. As illustrated in FIG. 1, the communication system 1 includes M communication pairs, namely, communication pair P(1) to communication pair P(M) (M is an integer equal to or greater than 1, and M=160 in this embodiment). A communication pair refers to a pair of a remote control terminal device and a control device that perform wireless communication according to a predetermined wireless communication standard such as the IEEE802.15 series. In this embodiment, the IEEE802.15.4 MAC, which is one of the specific low-power wireless communication standards, is adopted as the wireless communication standard. In the previous method of allocating a dedicated communication channel for each pair of remote control and device to be operated, the specified low-power wireless communication method (wireless equipment in the 400 MHz band with an occupied frequency bandwidth of 8.5 kHz or less) has 46 communication channels, meaning that the upper limit for the system is 46 devices, while the conventional specified low-power wireless communication method (wireless equipment in the 1200 MHz band with an occupied frequency bandwidth of 16 kHz or less) has 40 communication channels, meaning that the upper limit for the system is 40 devices.In contrast, with this method, 160 devices can operate in the system without a controlling parent unit, and the system is also resistant to interference, so the ratio of the number of devices accommodated is more effective than the numerical ratio.

[0018] The communication pair P(1) includes a control device 20 and a plurality of remote control terminal devices, such as a remote control terminal device 10A, a remote control terminal device 10B, a remote control terminal device 10C, and a remote control terminal device 10D. FIG. 1 illustrates a case in which the communication pair P(1) includes two remote control terminal devices. As shown in FIG. 1, the communication pair P(1) in this embodiment includes a remote control terminal device 10A and a control device 20, and the remote control terminal device 10B and the remote control terminal device 10C are stored as spares in case of a failure of the remote control terminal device 10A, or are installed as multi-operation devices. In the following, when it is not necessary to distinguish between the remote control terminal device 10A and the remote control terminal device 10B, each of the remote control terminal devices 10A, 10B, and 10C is referred to as a "remote control terminal device 10." 1, each of the communication pairs P(2) to P(M) includes one remote control terminal device 10 and one control device 20 that is paired with the remote control terminal device 10. The remote control terminal device 10 and the control device 20 included in one communication pair form one PAN (Personal Area Network).

[0019] The control device 20 is a communication module provided in an operation target device such as a crane or a shutter installed in a factory or indoors. The remote control terminal device 10 is a remote controller for remotely operating the device in which the control device 20 is provided by performing wireless communication according to a predetermined wireless communication standard with the control device 20 forming a communication pair. Hereinafter, the device including the control device 20 is referred to as an "operation target device". The control device 20 waits for a command transmitted from the remote control terminal device 10 and drives the operation target device according to the received command. In this embodiment, data may be transmitted from the control device 20 to the remote control terminal device 10. Specifically, an instruction and a response to change the communication frequency for the purpose of avoiding interference, and a response to an instruction from a maintenance terminal are transmitted from the control device 20 to the remote control terminal device 10.

[0020] In the communication system 1, K (K is an integer equal to or greater than 1, K=16 in this embodiment) communication channels defined in the wireless communication standard described above are available. FIG. 2 is a diagram showing an example of communication channel allocation in this embodiment. As shown in FIG. 2, in this embodiment, communication channels #1 to #16 are available, and N (N is an integer equal to or greater than 1 and equal to or less than M, N=10 in this embodiment) communication pairs are allocated to one communication channel, and the communication channel is shared by these N communication pairs. Hereinafter, the number of communication pairs sharing one communication channel is referred to as the "number of shared pairs." The number of shared pairs in this embodiment is N.

[0021] Specifically, as shown in Fig. 2, communication pairs P(1) to P(10) are assigned to communication channel #1. Although detailed illustration is omitted in Fig. 2, communication pairs P(11) to P(20) are assigned to communication channel #2, communication pairs P(21) to P(30) are assigned to communication channel #3, communication pairs P(31) to P(40) are assigned to communication channel #4, communication pairs P(41) to P(50) are assigned to communication channel #5, communication pairs P(51) to P(60) are assigned to communication channel #6, and communication pairs P(61) to P(70) are assigned to communication channel #7. Communication pair P(71) to P(80) are assigned to communication channel #8, communication pair P(81) to P(90) to communication channel #9, communication pair P(91) to P(100) to communication channel #10, communication pair P(101) to P(110) to communication channel #11, communication pair P(111) to P(120) to communication channel #12, communication pair P(121) to P(130) to communication channel #13, communication pair P(131) to P(140) to communication channel #14, communication pair P(141) to P(150) to communication channel #15, and communication pair P(151) to P(160) to communication channel #16.

[0022] When a first communication pair and a second communication pair share a single communication channel, if the data transmission timing of the first communication pair and the data transmission timing of the second communication pair overlap, the respective communications may be successful, but may fail due to collision of the respective communication waves. In other words, when a first communication pair and a second communication pair share a single communication channel, the communications of each communication pair are not always successful. For this reason, when remotely controlling a target device by wireless communication, it has been conventionally considered best to assign a dedicated communication channel to each communication pair and have the communication pair occupy the communication channel. This is because collision of communication waves does not occur if a dedicated communication channel is assigned to each communication pair and the communication pair occupies the communication channel.

[0023] In contrast, in this embodiment, by devising a transmission method for the remote control terminal device 10, it is possible to realize remote control of a target device by wireless communication without allocating a dedicated communication channel for each communication pair (i.e., without occupying a communication channel for the communication pair), and without impeding safety assurance and rapid response when an abnormality occurs. The following mainly describes the remote control terminal device 10, which prominently exhibits the features of the present disclosure.

[0024] Fig. 3 is a diagram showing a configuration example of the remote control terminal device 10. As shown in Fig. 3, the remote control terminal device 10 includes a control unit 110, an operation unit 120, a notification unit 130, a wireless communication unit 140, and a storage unit 150. Although detailed illustration is omitted in Fig. 3, the remote control terminal device 10 also includes a power supply unit that supplies operating power to each of the control unit 110, the operation unit 120, the notification unit 130, the wireless communication unit 140, and the storage unit 150. Specific examples of the power supply unit include a storage battery such as an alkaline dry battery or a secondary nickel-metal hydride battery.

[0025] The control unit 110 is, for example, a CPU (Central Processing Unit). The control unit 110 functions as a control center of the remote control terminal device 10 by operating according to a control program PR stored in the storage unit 150. Details of the processing executed by the control unit 110 according to the control program PR will be made clear later.

[0026] The operation unit 120 includes, for example, a plurality of operators. A user of the remote control terminal device 10 (a technology responsible for remotely operating the operation target device) performs various inputs for remotely operating the operation target device by operating a plurality of operators included in the operation unit 120. The operation unit 120 outputs operation content data indicating the content of the operation input by the user to the control unit 110. As a result, the user's operation content is transmitted to the control unit 110. The notification unit 130 includes, for example, a plurality of LEDs (Light Emitting Diodes) each having a different light emitting color, and causes these plurality of LEDs to emit light under the control of the control unit 110. In this embodiment, the state of the remote control terminal device 10 is notified to the user by a combination of the LEDs to be emitted among the plurality of LEDs. The notification unit 130 may include a display device that displays characters or images, such as a liquid crystal display, in addition to the plurality of LEDs or instead of the plurality of LEDs. When the notification unit 130 includes a display device, a touch sensor may be used as the operation unit 120, and the touch sensor and the display device may form a so-called touch panel.

[0027] The wireless communication unit 140 is, for example, a wireless communication transceiver, and transmits a communication message conforming to, for example, IEEE802.154 MAC to the control device 20 wirelessly. Fig. 4 is a diagram showing an example of a format of a communication message in this embodiment. As shown in Fig. 4, this communication message has a header and a payload following the header. Note that the communication message conforming to IEEE802.154 MAC includes a preamble preceding the header, but the preamble is omitted from Fig. 4.

[0028] As shown in FIG. 4, the header includes a sequence number, a PAN-ID, a destination address, and a source address. The sequence number is a serial number in the range of 0x00 to 0xFF that is counted up every time a communication message is transmitted. The PAN-ID is identification information that uniquely indicates the PAN (in other words, a communication pair) to which the remote control terminal device 10 that is the source of the communication message belongs, and this allows the uniqueness to be maintained and the communication pair to be formed without confusion. The uniqueness is maintained by writing the PAN-ID to the storage unit 150 when the remote control terminal device 10 is shipped from the factory, or by writing the PAN-ID from the outside using a physical switch or data. The destination address is the communication address of the control device 20 that is the destination of the communication message, and the source address is the communication address of the remote control terminal device 10 that is the source of the communication message. In addition to the PAN-ID, the destination address and the source address further maintain the uniqueness of the communication pair, and allow the communication pair to be formed without confusion. Note that any format is acceptable as long as it indicates the communication pair number, the source address, and the destination address.

[0029] As shown in Fig. 4, the payload includes the message Ver and the preliminary information. The message Ver is information indicating the version of the communication message, and the control device 20 can change the interpretation of the command information and the preliminary information depending on the value of the message Ver. In this embodiment, the preliminary information is unused, but it is considered to be used to transmit information regarding the communication channel or the remaining battery level of the remote control terminal device 10 to the control device 20. For example, by transmitting the remaining battery level of the remote control terminal device 10 to the control device 20, it becomes possible to cause the control device 20 to execute a notification regarding battery replacement, etc. of the remote control terminal device 10.

[0030] The wireless communication unit 140 is provided with data representing a communication message from the control unit 110, and the wireless communication unit 140 transmits the data by superimposing the data on a carrier wave of a communication channel assigned to the remote control terminal device 10. Various superimposing methods are covered by the patent. In the example of this embodiment, either the FM modulation method or the spread spectrum method may be used, but the spread spectrum method, which is resistant to demodulation during collisions, is used. When the control device 20 receives a communication message via a communication channel assigned to the control device, the control device 20 reads the PAN-ID and destination address from the header of the communication message, and if the former matches the PAN-ID of the PAN to which the control device belongs and the latter matches the communication address of the control device, the control device 20 receives the communication message as a communication message addressed to the control device, and performs drive control of the target device according to the command written in the command information of the payload of the message.

[0031] The storage unit 150 includes a non-volatile storage unit 152 and a volatile storage unit 154. The non-volatile storage unit 142 is, for example, a flash ROM (Read Only Memory). The non-volatile storage unit 152 stores a control program PR and a random number table TBL. The random number table TBL stores a random number sequence in which a plurality of real numbers are arranged. Although not shown in detail in FIG. 3, the non-volatile storage unit 152 stores a PAN-ID, a communication address assigned to the device itself, and a communication address assigned to the control device 20 that forms a communication pair with the device itself. The volatile storage unit 154 is, for example, a RAM (Random Access Memory). The volatile storage unit 154 is used by the control unit 110 as a work area when executing the control program PR.

[0032] When the remote control terminal device 10 is powered on, the control unit 110 reads the control program PR from the non-volatile storage unit 152 to the volatile storage unit 154 and starts executing the control program PR. The control unit 110 operating according to the control program PR performs burst transmission, which is a communication message including a command for instructing a controlled device such as a crane to operate, over a predetermined command transmission time T1, preferably intermittently at a fixed cycle, to a communication channel, and thereafter, until the next command is input, repeats burst transmission of the communication message while adjusting the execution timing by adding an offset according to a random number to a timing determined according to a predetermined cycle (hereinafter, basic cycle T2). The random number is converted so that the offset is 0 on average, and positive and negative values ​​are also converted. Note that during the period from the completion of burst transmission to the start of processing of the next burst transmission (the period of T2 + offset time - T1 - T3 in FIG. 6), the control unit 110 operates in a power saving mode (sleep mode) to reduce power consumption. Assuming that the device wakes up from sleep mode at time t1, during the period consisting of processing time T3 from time t1 to the start of command transmission and command transmission time T1, control unit 110 performs processing necessary for a wireless communication device equipped with a control unit, such as processing operation content data, detecting and processing device status and faults.

[0033] FIG. 5 is a diagram showing an example of burst transmission executed by the remote control terminal device 10, and FIG. 6 is a diagram showing an example of the execution period of burst transmission by the remote control terminal device 10. In this embodiment, the command transmission time T1 is 0.8 milliseconds, and the basic period T2 is 20 milliseconds. The processing time T3 until the start is 0.2 milliseconds, and the control unit enters the sleep mode after executing the necessary processing during the total of 1 millisecond of T3 and T1. In addition, the offset in this embodiment may be a value within the range of -19 milliseconds to 19 milliseconds, for example, and may take a value within the range of -2 milliseconds to 2 milliseconds when emphasizing the stability of the monitoring period of 20 millisecond intervals, or may take a value within the range of -19 milliseconds to 19 milliseconds when emphasizing the avoidance of collisions and the randomness. In addition, the offset value may take a value in units of 1 millisecond, which is a continuous analog numerical value, a multiple of the period of T1, or in units of 0.5 milliseconds, which is half of that. These are determined based on the importance of the requirements required for the system to which the offset is applied, such as the probability of collision avoidance, the stability of the period, and the price of the device. In this embodiment, the timing of burst transmission is not preset for each of the N remote control terminal devices 10 sharing one communication channel, but rather, the Aloha method is adopted in which each remote control terminal device 10 immediately executes burst transmission in response to a user's operation (in other words, burst transmission is executed randomly). Strictly speaking, the communication system 1 according to an embodiment of the present disclosure employs a method in which the ACK transmission function of the receiving control device is deleted from the Aloha method. Note that, as a mode in which the execution timing of burst transmission in each remote control terminal device 10 is preset, there is a slotted Aloha method, which is a time division method in which slots obtained by equally dividing a basic period into N are assigned one by one to each of the N remote control terminal devices 10, and the remote control terminal device 10 executes burst transmission in the slot assigned to itself. The slotted Aloha method reduces the collision probability by half compared to the Aloha method, making it possible to avoid collisions, but the remote control terminal device 10 needs a function to read the slot period timing. The slot period timing can be adjusted when the power is turned on or after it is turned on.When performed after startup, the slot synchronization time is adjusted by detecting signals of other different communication pairs on the communication channel to which the device belongs. When there are multiple pairs, the slot synchronization time is adjusted to the slot cycle timing of the communication pair with the strongest radio wave strength. When performed after startup, sleep is stopped periodically in units of a few seconds, a few minutes, or a few hours, and a search is performed to adjust the slot cycle timing. Alternatively, this is realized by a function in which the control device 20 transmits a slot timing signal of 1 millisecond or a frame timing signal of 20 milliseconds every regular period, such as 1 second, in this embodiment, and the remote control terminal device 10 searches and adjusts the slot cycle timing.

[0034] In this embodiment, the control unit 110 reads a random number from the random number table TBL and generates an offset value from this random number. When the offset value is set in units of 1 millisecond, which is a multiple of the period of T1, and is set in the range of -4 milliseconds to 4 milliseconds, the random number is divided by 9 and 4 is subtracted from the remainder to generate offset values ​​of -4, -3, -2, -1, 0, 1, 2, 3, and 4. The random numbers may be read from the random number sequence stored in the random number table TBL in a manner that reads them out one by one in sequence from the beginning of the random number sequence, or may be read out from a read position (address) that is converted by performing a predetermined calculation based on the current time.

[0035] In this embodiment, the random numbers stored in the random number table TBL are used, but the offset may be generated using pseudo-random numbers generated according to a known pseudo-random number generation algorithm instead of the random numbers. In other words, the random numbers in this disclosure include pseudo-random numbers generated according to a pseudo-random number generation algorithm. Specific examples of the pseudo-random number generation algorithm include a linear congruential generation algorithm and a Mersenne Twister generation algorithm. In the aspect of generating an offset using pseudo-random numbers, a device identifier unique to each remote control terminal device 10, such as a serial number such as a product number assigned by the manufacturer of the remote control terminal device 10, may be used as a seed in the pseudo-random number generation algorithm, or may be used as data from which the seed is generated.

[0036] The reason for adjusting the execution timing of burst transmission by adding an offset according to a random number is as follows: As described above, in the example of this embodiment, IEEE802, 15.4 MAC is adopted as the wireless communication standard for the communication pairs, and the distance at which the remote control terminal device 10 and the control device 20 can perform wireless communication without interference in IEEE802, 15.4 MAC is assumed to be L. Then, assume that the control device 20 of communication pair P(2) is placed within a circle of radius L centered on the control device 20 of communication pair P(1), and that each of the remote control terminal devices 10 of communication pair P(1) and communication pair P(2) is located within the circle.

[0037] In this situation, for example, at a certain time t0, the execution timing of burst transmission in communication pair P(1) and the execution timing of burst transmission in communication pair P(2) overlap, and wireless communication between the two fails due to collision of communication radio waves. In communication pair P(1), burst transmission is executed again at a timing adjusted by adding an offset to the timing 20 milliseconds after time t0 according to the random number R1 read from the random number table TBL of the remote control terminal device 10 included in communication pair P(1). Meanwhile, in communication pair P(2), burst transmission is executed again at a timing adjusted by adding an offset to the timing 20 milliseconds after time t0 according to the random number R2 read from the random number table TBL of the remote control terminal device 10 included in communication pair P(2).

[0038] The contents stored in the random number table of the remote control terminal device 10 included in the communication pair P(1) are different from the contents stored in the random number table TBL of the remote control terminal device 10 included in the communication pair P(2), and the random number R1 at time t0 is different from the random number R2. Therefore, the next burst transmission in the communication pair P(1) and the next burst transmission in the communication pair P(2) are executed at timings based on different random number generation values, and it is possible to prevent both from failing again with a probability of 7 / 9 (Aloha method). Even if there is another collision with a probability of 2 / 9, the next random number will result in a success rate of 1-(2 / 9) 2Two consecutive collisions are avoided with a probability of T2 = 77 / 81. To make the calculation easier to understand, we will assume T2 = 20 ms, T1 = 0.8 ms, and a completely random transmission ALOHA system, and consider the probability when two communication pairs are in a position where they interfere. We will make the strict assumption that a call will be lost if the transmission times of the communication pairs overlap even slightly.

[0039] The probability that one communication pair will lose a call due to another communication pair per transmission, P 11 , and the probability of two consecutive call losses P 12 are as follows, respectively. P 11 =1.6ms / 20ms=0.08=8%. P 12 =(P 11 ) 2 =0.64%.

[0040] As a worst case scenario, consider a situation where there are 10 communication pairs on one communication channel. The probability that one communication pair will be lost per transmission due to the other 9 communication pairs is P 91 , and the probability of two consecutive call losses P 92 are as follows, respectively. P 91 =1-(1-P 11 ) 9 ≒0.528=53%. P 92 =(P 91 ) 2 =28%.

[0041] Since transmissions are made every 20 milliseconds, the probability of six consecutive call losses, or the probability of not being able to connect for 100 milliseconds, is P 96 , the probability of 11 consecutive call losses, i.e., the probability of not being able to connect for 200 milliseconds, P 911 , the probability of 21 consecutive call losses, i.e., the probability of not being able to connect for 400 milliseconds, P 921 , and the probability of 26 consecutive call losses, i.e., the probability of not being able to connect for 500 milliseconds, P 926 are as follows, respectively. P 96 =(P 91 ) 6≒0.0216=2.2%. P 911 =(P 91 ) 11 =0.08%. P 921 =(P 91 ) 21 =1.5ppm. P 926 =(P 926 ) 11 =0.06ppm. These can be interpreted as the probability of a signal delay due to a collision. In other words, the probability of a signal being delayed by 500 milliseconds or more is 0.06 ppm.

[0042] The above calculations are based on the worst case scenario. In reality, however, 10 communication pairs on the same communication channel will interfere with each other when 160 communication pairs are concentrated within a radius of L. If L = 50 m, the interference will be 49(7 2 )m 2 This is the density where there is one communication pair of remote control terminal devices on the same channel. This does not include the calculation of collision avoidance due to the difference in wireless reception level caused by the difference in distance, so in reality the installation density is even higher. 11 = 8%, but when using a spread spectrum method that complies with IEEE802.15.4 MAC, the actual value is P 11 = 2%. 91 =16.6%. Probability of not being able to connect for 100 ms P 96 = 21 ppm, probability of not being able to connect for 140 ms P 98 = 0.6 ppm. 11 The probability of not being able to connect for 140 ms when the time is 2% is 0.6 ppm. 11 This is lower than the 1.5 ppm probability of not being able to connect for 400 ms when the rate is 8%, and is a significantly better value.

[0043] P 11 = 2%, P 96 =(P 91 ) 6 = 21 ppm, so the probability of a signal delay of 100 ms or more is 21 ppm, and P 911 =(P91 ) 11 = 0.0027 ppm, the probability of a signal delay of 200 milliseconds or more is 0.0027 ppm, which is a level of delay that will not cause any problems in practical operation in terms of safety and immediacy.

[0044] If the system requirements for the application require a shorter delay time, the ALOHA system can be changed to the Slotted ALOHA system, resulting in a reduction in P 11 This reduces the delay time by half, resulting in a significant reduction in the delay time. 11 =2% to P 11 = 1%, so P 96 is reduced from 21 ppm to 0.4 ppm. The probability of 21 ppm is reduced from 100 ms to 68 ms. The time to 0.1% call loss is reduced from 57 ms to 36 ms.

[0045] There are various methods to reduce delay time. Examples (1) to (7) are shown below. (1) Physical measures such as reducing the number of units and (2) increasing the physical distance between communication pairs are effective. Other measures include (3) creating a unique optimal protocol that removes unnecessary information elements and shortens the wireless signal output time T1. Other methods include (4) setting T2 = 20 milliseconds for only 1 second from the point of change when the button is pressed or released, and setting T2 = 100 milliseconds when there is no change. (5) In the case of an important signal that requests the operation of the power while the button is pressed, there is also a method in which T2 = 20 milliseconds for only 1 second from the point of change when the button is pressed and released, and setting T2 = 200 milliseconds when there is no change after the button is released. (6) Although it is expensive because both the remote control terminal device and the control device have wireless transmission and reception functions, there is also a method in which, when a change occurs when the button is pressed or released, a continuous transmission is made at intervals of, for example, T2 = 20 milliseconds, and when the control device receives the signal, it returns an ACK signal, and when the remote control terminal device receives it, it stops transmitting from the remote control control device. From the viewpoint of ensuring safety, it is also possible to turn off the power when the signal is interrupted for 500 ms or more. In this embodiment, T2 is set to 20 milliseconds. However, in terms of reducing the collision probability and minimizing the transmission delay time, this is not the optimal value due to the number of communication pairs that may collide. For this reason, there is a method (7) of optimizing T2.

[0046] We will explain how to determine the optimal value of T2 to shorten the delay time. For example, if we define the time when the call loss rate becomes 0.1% as t0.1%, then we obtain the following function. Assume that N communication pairs in the Aloha system cause interference. t0.1%=T2*[-3 / log{1-(1-2*T1 / T2) N-1}-1]

[0047] When it is desired to determine the shortest time, T1, N, and the call loss rate are fixed, and T2 is varied to determine the time. In this embodiment, an example is given in which N≦10, T1=0.8 ms, and T2=20 ms. When N=3, the shortest time for the call loss rate to be 0.01% is 64.1 ms, and the condition is T2=7.7 ms. When T2=20 ms, the shortest time increases to 78.3 ms. When N=3, the shortest time for a call blocking rate of 1% is 27.6 ms, and this is the condition for T2=10.5 ms. When T2=20 ms, the shortest time increases to 29.2 ms. When N=10, the shortest time for a call blocking rate of 0.1% is 189.59 ms, and the condition is T2=28.5 ms. When T2=20 ms, the shortest time increases to 196.2 ms. FIG. 7 shows a graph of T2=transmission interval (ms) vs. clear time (ms) based on the call loss rate. In Fig. 7, the horizontal axis corresponds to the transmission interval (ms) which is T2, and the vertical axis corresponds to the time (ms) to clear the call loss rate criterion. Curves G1, G2, and G3 in Fig. 7 show the relationship between the transmission interval (ms) and the clear time (ms) of the call loss rate criterion when N=5, T1=0.8 ms, and the call loss rate=1%, 0.1%, and 0.01%, respectively. Curves G4, G5, and G6 in Fig. 7 show the relationship between the transmission interval (ms) and the clear time (ms) of the call loss rate criterion when N=10, T1=0.8 ms, and the call loss rate=1%, 0.1%, and 0.01%, respectively. Curves G7, G8, and G9 in FIG. 7 show the relationship between the transmission interval (ms) and the clearing time (ms) based on the call loss rate when N=3, T1=0.8 ms, and call loss rates=1%, 0.1%, and 0.01%, respectively.

[0048] In the case of the slotted aloha system, the formula is as follows: t'0.1%=T2*[-3 / log{1-(1-T1 / T2) N-1}-1]

[0049] In this embodiment, the offset value is set in units of 1 millisecond, which is a multiple of the T1 cycle, and is set in 9 steps of ±4 milliseconds. The recollision probability is 21%. If it is set in 17 steps of ±8 milliseconds, the fixed periodicity is lost, collisions with multiple cycles occur and complexity increases, but the recollision probability decreases to 12%. If fixed periodicity is important, a setting of 3 steps of ±1 millisecond is better, but the recollision probability increases to 56%.

[0050] For the above reasons, there is a method (8) of changing the width of the offset value. A method of changing the width of the offset value to shorten the delay time will be described. In this embodiment, the offset value is set in units of 1 millisecond, which is a multiple of the period of T1, in the ALOHA method, and is set in the range of -4 milliseconds to 4 milliseconds. In this case, the probability that two communication pairs using the same channel will collide again after colliding once is calculated to be 2 / 9. A detailed calculation gives 1 / 9*2 / 9*8+1 / 9*2 / 9*1=17 / 81=0.210<0.222=2 / 9, and the call loss rate is a little smaller. In this example, the range is ±4 milliseconds, but in the case of ±u milliseconds, the collision probability is (4u+1) / (2u+1) 2 However, T2 is 20 milliseconds and u<7. When u is 7 or more, the calculation formula changes because the calculation of collisions during multiple cycles is included. When u=7~9, the collision probability is (4u+1) / (2u+1) 2 +{6*(u-6)*(3u-19)+1} / 2 / (2u+1) 3 It is. When u=1, the probability of a recollision after a collision is 0.556 When u=2, the probability of a recollision is 0.360 When u=3, the probability of a recollision is 0.265 When u=4, the probability of a recollision is 0.210 When u=5, the probability of a recollision is 0.174 The probability of a recollision when u=6 is 0.148 The probability of a recollision when u=7 is 0.131 The probability of a recollision when u=8 is 0.120 The probability of a recollision when u=9 is 0.113 When u=10, the probability of a recollision is 0.107 For a call that occurs completely randomly, 1 / 20 of the time, the probability is 2 / 20 = 0.100. By changing the offset value as described above, it is possible to reduce the probability of re-collision, the call loss rate, and the delay time. On the other hand, the fixed periodicity tends to be lost.

[0051] The above describes the method for reducing the delay time. On the other hand, if the system requires an increased number of devices to be accommodated, the same measures as for reducing the delay time should be taken. A similar study should be carried out and the system should be changed.

[0052] The above is the configuration of the remote control terminal device 10.

[0053] Next, the operation of the remote control terminal device 10 will be described.

[0054] When a button operation for remotely controlling a controlled device (for example, a crane) is performed on the operation unit 120, the control unit 110 operating according to the control program PR burst transmits a communication message including a command corresponding to the operation (hereinafter, a first command) to the control device 20, and after the burst transmission is completed, executes the control method shown in Fig. 8. As shown in Fig. 8, this control method includes the processes of steps SA110 to SA150. The process contents of each process of steps SA110 to SA150 are as follows.

[0055] In step SA110, the control unit 110 acquires a random number by referring to the random number table TBL of the own device. When the process of step SA110 is executed again, the control unit 110 reads the random number from a read position different from that in the previous execution of step SA110.

[0056] In step SA120 following step SA110, control unit 110 converts the random number acquired in step SA110 into an offset, for example, in the range of -4 to 4, adds a time T2 corresponding to the period to the offset, and sets the value obtained by subtracting T1 and T3 as the sleep time.

[0057] Next, when control unit 110 receives a burst transmission completion notification from wireless communication unit 140 (step SA130), it executes a sleep for the sleep time set in step SA120 (step SA140). Then, after the sleep time has elapsed, control unit 110 executes a start-up process (step SA150).

[0058] In the burst transmission after the flowchart in Figure 8 is completed, the control unit 110 checks the input value of the button state on the operation unit 120, and if there is no change in the button operation, it simply burst transmits the same communication message as last time.If there is a change in the button operation and the input value has changed, it simply resets the communication message in accordance with the operation on the operation unit 120 and performs burst transmission.

[0059] In addition, when the control device 20 judges that it is better to change the communication channel due to the reason that an interference wave or a jamming wave is detected in a predetermined communication channel, the control device 20 executes the operation shown in the flowchart of FIG. 9. When an interference wave or a jamming wave is detected in a predetermined communication channel, the control device 20 searches the communication channels #1 to #16 as shown in FIG. 9 and determines a communication channel that is less susceptible to interference or jamming as a new communication channel (step SB110). Next, the control device 20 transmits an instruction to change the communication channel to the communication channel to the remote control terminal device 10 (step SB120). When the control unit 110 of the remote control terminal device 10 receives an instruction to change the communication channel, that is, an instruction to change the communication frequency, from the control device 20 paired with the control device 20, the control unit 110 changes the communication channel according to the instruction and executes a burst using the new communication channel. The control device 20 waits for reception of data to be burst-transmitted in the new communication channel (step SB130), and when data is received in the new communication channel (step SB130: Yes), it transmits a response to the new communication channel (step SB140). The change of the communication channel is completed when the remote control terminal device 10 receives the response. If the control device 20 does not receive data even after a predetermined time has elapsed since the control device 20 transmitted the change instruction, the determination result of step SB130 is "No," and in the operation example shown in Fig. 9, the control device 20 executes the process from step SB110 onward again.

[0060] Alternatively, after changing the remote control terminal device 10 to the maintenance mode, a signal instructing the control device 20 to change from a predetermined communication channel to a different communication channel may be sent by operating a button or by setting from a maintenance terminal. When the control device 20 receives the signal, it returns a response signal, and then the control device 20 and the remote control terminal device 10 change to the communication channel, and the remote control terminal device 10 transmits a burst signal and returns a response, completing the change. The remote control terminal device 10 may be a dedicated maintenance-use remote control terminal device. In addition, in the maintenance mode of the remote control terminal device 10, a function may be provided to search the communication channels #1 to #16 and display the degree of influence of interference or disturbance, or to transmit the degree of influence to the control device 20 or the maintenance terminal. If the control device 20 does not receive a response signal from the remote control terminal device 10 a fixed number of times or after waiting a specified time from the transmission of the change instruction, the control device 20 may return to the original channel and repeat the process of transmitting the change instruction again a fixed number of times. If the channel change is unsuccessful even after repeating this process a predetermined number of times, the algorithm may return to the original channel, or search communication channels #1 to #16 again and issue an instruction to change to a different channel.

[0061] In addition, in the maintenance mode, the remote control terminal device dedicated to maintenance, or the maintenance terminal may indicate to the control device an identifier indicating that the backup information is FF, or that the source address is FF, etc., indicating that the signal is a maintenance signal. When a destination address is specified, only the control device of that address processes the maintenance signal, and when the destination address is FF, all control terminals determine that the identifier is a maintenance instruction, and all terminals receive the maintenance signal. When an operation target device including the control device 20 receives an instruction from a maintenance terminal that performs remote maintenance of the operation target device, executes processing according to the instruction, and returns a response to the maintenance terminal, the control device 20 transmits the response to the remote control terminal device 10 that is paired with the device itself. When the control unit 110 in the remote control terminal device 10 that receives the response receives the response, it executes processing according to the response, such as stopping the burst transmission that is being executed at that time.

[0062] Specifically, the effects of this embodiment are as follows. 10 is a diagram showing actual measurement values ​​of the D / U ratio and call loss rate between terminals when collision occurs over the air in the communication system 1. As described above, in the communication system 1 according to an embodiment of the present disclosure, the calculated probability of collision between two communication pairs under strict preconditions that a call is always lost when the transmission times of the communication pairs overlap even slightly, in an Aloha system with T2=20 ms, T1=0.8 ms, and completely random transmission, is P 11 = 1.6 ms / 20 ms = 0.08 = 8%. Comparing the actual measurements with the calculations, the call loss rate when the D / U ratio between terminals is -3 dB or less is 7.2%, which is close to the calculated value.

[0063] The D / U ratio indicates the radio wave strength from the paired remote control terminal device 10 / the radio wave strength from the unpaired remote control terminal device 10 in the received radio wave level received by the control device 20. A D / U ratio of -3 dB between terminals indicates that the radio wave strength from the unpaired remote control terminal device 10 is 3 dB higher than the radio wave strength from the paired remote control terminal device 10, and indicates that when the distance from the control device 20 to the paired remote control terminal device 10 is 3 m, the unpaired remote control terminal device 10 is 2.1 m (√2) away from the control device 20.

[0064] Generally, when radio waves collide in wireless communication, if the D / U ratio is 8dB or more, the signal can be regenerated. In reality, the impact becomes significant when the D / U ratio is 6dB or less, and when it is 3dB or less, there is a complete collision, the signal cannot be regenerated, and a call loss rate based on the collision calculation occurs.

[0065] The communication system 1 according to an embodiment of the present disclosure uses small packets that limit the amount of data to 0.8 milliseconds even including a preamble, and is resistant to collisions due to the effect of using a spread spectrum method, etc. When the D / U ratio is 3 dB or more, the call loss rate upon collision is 27% of the calculation, and even at 0 dB, the call loss rate upon collision is small at about 40% of the calculation, and when collision occurs at -3 dB or less, it is 90%, close to the calculated value.

[0066] As described above, according to this embodiment, it is possible to realize remote control of the target device by a remote controller through wireless communication without occupying a communication channel and without impeding safety assurance and prompt response when an abnormality occurs. In addition, in this embodiment, even if N communication pairs sharing one communication channel exist within a circle of radius L, which is the effective range of wireless communication, there is no impediment to safety assurance and prompt response when an abnormality occurs. Therefore, it is not necessary to visit the factory to carry out investigation, measurement, and setting work such as to prevent the same communication channel from being assigned to adjacent target devices in accordance with the arrangement of each target device in the factory, and the introduction cost of the communication system 1 can be reduced compared to the embodiment requiring such work.

[0067] Specifically, 10 communication pairs (P1 to P10) can share the communication channel #1. Since there are 16 communication channels, 160 pairs can be used in the same place. The remote control terminal device 10 included in each of the communication pairs P1 to P10 transmits signals intermittently (0.8 milliseconds) and periodically (20 milliseconds). Signal collisions are avoided by transmitting signals with a random offset at a predetermined period, so although signal collisions occur between the 10 pairs, the signals are transmitted to the control device with a certain probability. The collision probability and call loss rate, which are determined by the number of accommodated vehicles and the distance between the communication pairs, are further converted into a function of the control delay time. Since the method allows the mixing of 10 pairs even on the same channel, 160 pairs, about four times the number of pairs that were previously available, can be used, and no adjustments by radio engineers are required. It can be operated simply by installing equipment that is randomly set in the factory. The number of pairs and the period used here are just examples, and it is possible to accommodate even more communication pairs. This method can be optimized to meet requirements such as control delay time constraints, number of devices accommodated, and cost requirements by adjusting the transmission cycle time (T2) and the width of the transmission timing offset value.In addition, this method can be optimized to meet requirements by selecting between Aloha and Slotted Aloha methods, whether or not to respond from control devices, and whether or not to have a channel change function.

[0068] <2. Transformation> The above description of the embodiment is for the purpose of explaining the present disclosure, and should not be interpreted as limiting the invention described in the claims or narrowing the scope. In addition, the configurations of the various parts of the present disclosure are not limited to the above embodiment, and various modifications are possible within the technical scope described in the claims.

[0069] (1) In the above embodiment, the device to be operated is a crane installed in a factory, but it may be a hoist, winch, or chain block. It may also be a fire shutter whose opening and closing is controlled by a remote control, control of a pump for medical use, control of agricultural equipment, control of an air conditioner, a mobile cart, or a robot. The control includes not only start and stop, but also speed control, selection switch control, emergency stop control, etc. In addition, it may be control of a personal computer, display, television, lighting system, etc., with or without power.

[0070] (2) In the above embodiment, the contents stored in the random number table TBL in each of the N communication pairs sharing one communication channel are different from each other, but it is not necessarily required that the contents stored in these N random number tables TBL are different from each other, and more than one of them (including N) may be the same. If the N random number tables TBL include the same ones, no particular problem will occur if the read position is adjusted for each remote control terminal device 10 based on the device identifier. In other words, the communication system disclosed herein includes N pairs (N is an integer of 1 or more) of remote control terminal devices and control devices, and each of the multiple remote control terminal devices has a wireless communication unit that transmits data to the control device paired with the device by wireless communication on a predetermined communication channel, and a control unit that adjusts the execution timing of the wireless communication by the wireless communication unit by adding an offset corresponding to a random number to a timing determined according to a predetermined period, and further, the multiple remote control terminal devices are given identification information for uniquely identifying each of them, and the control unit included in each of the multiple remote control terminal devices may generate the random number based on the identification information of the device.

[0071] (3) The present disclosure may be defined as a program (the control program PR in the above embodiment) that causes a general computer such as a CPU to execute the control method shown in Fig. 8, and the program may be manufactured or provided as a standalone program. Specific examples of how the program may be provided include a program written to a computer-readable recording medium such as an SD memory card and distributed, or a program downloaded via a telecommunications line such as the Internet.

[0072] (4) The remote control terminal device 10 transmits bursts in communication with the control device 20, and when communication with the control device 20 is not possible, if a predetermined condition such as the passage of a certain period of time is satisfied, the control device 20 can stop the operation of some or all of the controlled devices, for example, stop motor control. In addition, the remote control terminal device 10 has wireless communication (bidirectional) in communication with the control device 20, and the control device 20 can stop the operation of some or all of the controlled devices, for example, stop motor control, through that communication.

[0073] (5) The communication system 1 of the present invention can adjust the transmission cycle time (T2) to optimize the system to meet the requirements of call loss rate, control delay time, number of devices accommodated, and cost. It can also adjust the width of the offset value of the transmission timing to optimize the system to meet the requirements. It can also adjust and optimize the transmission cycle time (T2) when control changes, when control does not change, or when idle.

[0074] (6) In addition, it is possible to select between Aloha and Slotted Aloha methods, whether to have a response from the control device, and functions such as channel changing and interference search, allowing the optimization of functionality, performance, and investment costs.

[0075] (7) The communication system 1 of the present invention can provide a highly safe method and system by having a function of automatically turning off the power of the control equipment or raising an alarm when the signal from the remote control device is lost for a certain period of time or when interference waves are detected for a certain period of time or longer.

[0076] (8) Furthermore, the communication system 1 of the present invention can provide a highly secure method and system by configuring it to automatically or manually change channels when it detects a signal interruption or interference from a remote control device for a certain period of time or more. It can also be equipped with a maintenance mode to forcibly execute investigations and instructions for safe operation. [Explanation of symbols]

[0077] 1. Communication systems 10, 10A, 10B, 10C, 10D... Remote control terminal device 20...Control device 110...Control unit 120...Operation unit 130…Notification department 140...Wireless communication unit 150...Storage section 152...Non-volatile memory unit 154...Volatile memory unit

Claims

1. The system includes N pairs of remote control terminal devices and control devices (N is an integer of 1 or more), Each of the N remote control terminal devices a wireless communication unit that transmits data to a control device paired with the device itself by wireless communication on a predetermined communication channel; A control unit that adjusts a timing of execution of the wireless communication by the wireless communication unit by adding an offset corresponding to a random number to a timing determined according to a predetermined cycle. A communication system comprising:

2. The wireless communication unit included in each of the N remote control terminal devices is transmitting intermittent periodic bursts over said communication channel for a predetermined period of time; 2. The communication system according to claim 1 .

3. When the N control devices detect interference or disturbance in a communication channel used for wireless communication with a remote control terminal device paired with the control device, the N control devices transmit a change instruction to the remote control terminal device paired with the control device to instruct the control device to change the communication channel; the control unit included in each of the N remote control terminal devices changes the communication channel used for transmitting data to the control device paired with the respective remote control terminal devices in response to the change instruction; The communication system according to claim 1 .

4. When the N control devices detect interference or disturbance in a communication channel used for wireless communication with a remote control terminal device paired with the device itself, the N control devices determine a communication channel that is less susceptible to interference or disturbance by searching for the presence or absence of interference or disturbance in each of a plurality of communication channels different from the communication channel, and transmit a change instruction to the remote control terminal paired with the device itself to instruct the device to change to the determined communication channel. The communication system according to claim 3.

5. The control device that has transmitted the change instruction returns a response when it receives data from a remote control terminal paired with the control device through wireless communication on the communication channel that has been instructed to change the communication channel; completing the change of the communication channel when the remote control terminal that has changed the communication channel and transmitted the data in response to the change instruction receives the response; 5. The communication system according to claim 4.

6. When the control device that transmitted the change instruction fails to receive data a predetermined number of times from the remote control terminal device paired with the control device itself through wireless communication of the communication channel instructed to be changed, or fails to receive data from the remote control terminal device paired with the control device itself within a predetermined time period after the transmission of the change instruction, the control device returns to the original communication channel and repeats the process of transmitting the communication channel change instruction again a predetermined number of times, and when the communication channel change is not successful even after repeating the process a predetermined number of times, the control device returns to the original communication channel or searches the multiple communication channels again and transmits the change instruction to a different communication channel.

6. The communication system according to claim 5.

7. When the N control devices detect interference or disturbance in a communication channel used for wireless communication with a remote control terminal device paired with the control device, the N control devices transmit a change instruction to the remote control terminal device paired with the control device to instruct the control device to change the communication channel; the control unit included in each of the N remote control terminal devices changes the communication channel used for transmitting data to the control device paired with the respective remote control terminal devices in response to the change instruction; The communication system according to claim 2 .

8. Each of the N remote control terminal devices is a remote controller for remotely controlling N different operation target devices, while each of the N control devices is included in each of the N operation target devices; Each of the N control devices transmits a response in response to an instruction received from a maintenance terminal that performs remote maintenance of the operation target devices including the control device to a remote control terminal device that is paired with the control device; the control unit in each of the N remote control terminal devices executes a process in response to the response received via the wireless communication unit. A communication system according to any one of claims 1 to 7.

9. a wireless communication unit that transmits data to a control device paired with the device itself by wireless communication on a predetermined communication channel; a control unit that adjusts a timing of execution of the wireless communication by the wireless communication unit by adding an offset corresponding to a random number to a timing determined according to a predetermined cycle; A remote control terminal device comprising:

Images