Multi-device system without networking function and clock calibration method thereof

Abstract

The invention discloses a multi-device system without a networking function and a clock calibration method thereof. The clock calibration method of the multi-device system without the networking function comprises the following steps: when a device initiates a clock calibration request, each device obtains a value of a factor parameter which has an influence on a clock; calculating the environment weight of the equipment clock according to the value of the factor parameter and the corresponding weight; each device calculates the time accuracy of the device according to the environment weight and the historical calibration weight of the clock of the device, and sends the time of the device and the time accuracy to other devices in the system; and each device calculates the average time according to the time and the time accuracy of all the devices, judges whether the own time is deviated from the average time or not, and if so, adjusts the own time to the average time. According to the invention, through the statistics of the time and the time accuracy of each device in the system, the time of other devices is automatically calibrated by using relatively accurate time, so that the cost of manual calibration is reduced.

Description

Technical Field

[0001] This invention relates to the technical field of clock calibration, and more particularly to a clock calibration method for a multi-device system without network connectivity. Background Technology

[0002] While many existing devices are network-enabled, and network-enabled terminals generally use network time for synchronization, enabling high-precision time calibration, some devices are resource-constrained and lack network capabilities. For example, temperature controllers and control panels installed in various spaces in modern building control systems are small in size and numerous, and their functional expansion is limited due to cost, size, and other factors, thus they lack network functionality. In addition, some non-networked smart door locks or window locks are also similar resource-constrained devices.

[0003] These resource-constrained devices have relatively simple functions and limited processing power. They typically use low-cost, low-power microcontrollers with low clock speeds and limited memory (RAM / Flash). They cannot run complex network protocol stacks (such as TCP / IP) and lack network interfaces. However, these devices are usually directly user-facing, needing to display the time and execute user-defined timed tasks. They have high requirements for absolute time accuracy and consistency across multiple devices. However, their built-in clock modules (such as RTC circuits) usually rely on crystal oscillators. Crystal oscillators are susceptible to factors such as temperature changes, aging, and power supply fluctuations, causing clock drift, which necessitates frequent time calibration for these devices.

[0004] Taking environmental control in modern buildings as an example, there are numerous temperature controllers and corresponding control panels, many of which lack network connectivity. However, clock displays and timer functions have become fundamental and crucial user interaction features. Accurate time display directly impacts the user's reliance on timed tasks (such as timed on / off, sleep mode, energy-saving control, etc.).

[0005] Current technologies typically employ manual calibration for these devices. However, for applications with numerous devices, such as buildings with hundreds of control panels, even if some control panels have local communication connections, manual calibration of each group of control panels on-site by maintenance personnel is extremely time-consuming, labor-intensive, and costly. Moreover, clock drift is a persistent issue, making frequent and repeated manual calibrations prohibitively expensive for maintenance personnel.

[0006] Therefore, how to provide a multi-device system without network connectivity that can reduce manual maintenance and its clock calibration method is a technical problem to be solved. Summary of the Invention

[0007] To address the technical problem that time calibration in existing multi-device systems without network connectivity requires manual intervention, this invention proposes a multi-device system without network connectivity and its clock calibration method.

[0008] The clock calibration method for a multi-device system without network connectivity proposed in this invention includes:

[0009] When a device initiates a clock calibration request, each device obtains the values ​​of factor parameters that affect the clock.

[0010] Calculate the environmental weight of the device clock based on the values ​​of the factor parameters and their corresponding weights;

[0011] Each device calculates its time accuracy based on its clock's environmental weight and historical calibration weight, and sends its own time and time accuracy to other devices in the system;

[0012] Each device calculates the average time based on the time of all devices and the time accuracy, and determines whether its own time deviates from the average time. If so, it adjusts its own time to the average time.

[0013] Furthermore, the factor parameters include at least one of the following: ambient temperature, ambient humidity, equipment vibration status, equipment electromagnetic interference status, and equipment component aging status.

[0014] Furthermore, when the multi-device system is a refrigeration system, the vibration state of the equipment includes at least one of the following: shutdown, only fan on, only compressor on, and both fan and compressor on.

[0015] Furthermore, the environmental weight of the device is calculated using the following method:

[0016] Multiply the weight corresponding to the factor parameter and the proportion of the factor parameter to obtain the weight ratio of each factor parameter of the device;

[0017] The environmental weight is obtained by summing the weight ratios of all the factor parameters of a device.

[0018] Furthermore, at the start of the initial automatic calibration of the multi-device system, any one of the devices initiates a clock calibration request according to a preset transmission interval.

[0019] Furthermore, after each clock calibration, the device adjusts the sending interval of the next clock calibration request based on the deviation between its own time and the average time, according to the sending interval of the previous clock calibration request, and starts timing from zero.

[0020] Furthermore, the historical calibration weights of the device are calculated using the following method:

[0021] The theoretical calibration deviation is calculated using the formula △t'=△t2*△ta' / △t1, where △ta' is the deviation during the last calibration, △t1 is the sending interval of the last clock calibration request, and △t2 is the sending interval of the current clock calibration request.

[0022] The corresponding historical calibration weight is determined based on the value of the theoretical calibration deviation.

[0023] Furthermore, the time accuracy of the device is calculated by multiplying its environmental weight by its historical calibration weight.

[0024] Furthermore, when the time accuracy of a device exceeding a preset ratio threshold falls below a preset accuracy, the user is prompted to manually calibrate the time, and the system broadcasts this to other devices to synchronize their device time.

[0025] The multi-device system proposed in this invention includes devices connected via a bus. Each device includes a control module and a clock module. The control module calibrates the time of its clock module using any of the clock calibration methods for multi-device systems without network connectivity described in the above technical solutions.

[0026] This invention facilitates the exchange of time information through local communication between devices in a network-free multi-device system. It dynamically evaluates the time accuracy weight by combining the device's environment with historical calibration data, and calculates the global calibration time using a "weighted averaging" algorithm. This avoids reliance on a single time source and can also filter out devices with abnormal times. The weighted filtering mechanism ensures overall calibration accuracy. When the time reliability of most devices is 0, a user intervention prompt is triggered to achieve rapid synchronization across the entire network after manual calibration. This ensures the time accuracy of all devices in the system while significantly reducing the cost of manual calibration. Attached Figure Description

[0027] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0028] Figure 1 This is a main flowchart of an embodiment of the present invention.

[0029] Figure 2 This is a structural block diagram of a device according to an embodiment of the present invention.

[0030] Figure 3 This is a schematic diagram of the weighting of ambient temperature according to an embodiment of the present invention.

[0031] Figure 4 This is a schematic diagram of the weighting of environmental humidity according to an embodiment of the present invention.

[0032] Figure 5 This is a schematic diagram of the weight division corresponding to the vibration state in an embodiment of the present invention.

[0033] Figure 6 This is a schematic diagram of the weight division corresponding to the electromagnetic interference state according to an embodiment of the present invention.

[0034] Figure 7 This is a schematic diagram of the weight division corresponding to the cumulative running time in an embodiment of the present invention.

[0035] Figure 8 This is a schematic diagram of the proportional coefficient division corresponding to the factor parameters in an embodiment of the present invention.

[0036] Figure 9 This is a schematic diagram of the weighting of historical calibration deviations according to an embodiment of the present invention.

[0037] Figure 10 This is a schematic diagram of time information acquired by a device according to an embodiment of the present invention.

[0038] Figure 11 This is a flowchart of an embodiment of the present invention. Detailed Implementation

[0039] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] Therefore, a feature pointed out in this specification is used to describe one feature of one embodiment of the invention, and does not imply that every embodiment of the invention must have the described feature. Furthermore, it should be noted that this specification describes many features. Although certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0041] This invention addresses resource-constrained multi-device systems and proposes various embodiments of clock calibration methods for multi-device systems without network connectivity in order to reduce manual calibration operations.

[0042] In a basic embodiment, such as Figure 1 As shown, the clock calibration method for a multi-device system without network connectivity according to the present invention includes the following main steps.

[0043] When a device initiates a clock calibration request, each device obtains the values ​​of factor parameters that affect the clock.

[0044] Calculate the environmental weight of the device clock based on the values ​​of the factor parameters and their corresponding weights;

[0045] Each device calculates its time accuracy based on its clock's environmental weight and historical calibration weight, and sends its own time and time accuracy to other devices in the system;

[0046] Each device calculates the average time based on the time of all devices and the time accuracy, and determines whether its own time deviates from the average time. If so, it adjusts its own time to the average time.

[0047] In the above embodiments, each device acquires the values ​​of factor parameters that affect the clock. These values ​​can be real-time values ​​or all collected values ​​of factor parameters from the last calibration to the current calibration. All collected values ​​can be filtered and their average value can be selected to comprehensively consider the values ​​of influencing factors over a period of time.

[0048] Different devices operate in different environments, resulting in different factors affecting their clocks. For example, in environments with high humidity, humidity significantly impacts the clock, making it a key factor. Conversely, in environments with high electromagnetic interference, electromagnetic interference significantly impacts the clock, making it a key factor. Therefore, the influencing factors for each device may differ. In some embodiments, the influencing factors for all devices can be set to be the same; for example, all devices may have influencing factors including temperature, humidity, and electromagnetic interference. However, given the different environments in which devices operate, the weight of electromagnetic interference, which has a significant impact due to humidity, can be set relatively high, while the weights of other less influential factors can be set extremely low, having little or no impact on the environmental weights of the device clocks. This simplifies the control logic while ensuring that the environmental weights for different devices are determined based on their specific environments.

[0049] The aforementioned historical calibration weights are primarily determined by the deviation between the device's time and the average time during one or more previous calibration processes. A larger deviation indicates that the device's clock is more susceptible to environmental influences, thus the historical calibration weights should be relatively smaller to prevent the device's clock from having a decisive impact on the system's average time.

[0050] Based on the above technical solution, this invention realizes automatic clock calibration for multi-system devices without network connectivity. By setting environmental weights and historical calibration weights, the time of each device is considered. The time of devices with relatively accurate clock modules is taken as the main consideration, while the time of devices with relatively inaccurate clock modules is reduced in weight to avoid affecting the average time. The final calculated average time is a relatively accurate time that can be used for automatic calibration of devices within the system, avoiding the trouble and cost of manual calibration.

[0051] In one embodiment, the factor parameters include at least one of the following: ambient temperature, ambient humidity, equipment vibration status, equipment electromagnetic interference status, and equipment component aging status. Depending on the environment, some systems may include only one of the listed factor parameters, while others may include multiple listed parameters. Still others may include other factor parameters in addition to the listed parameters, depending on their specific environment. Even newly added factor parameters can be used to perform relatively accurate automatic time calibration using the concept of this invention.

[0052] When the multi-device system is a refrigeration system, the equipment vibration state includes at least one of the following: shut down, fan only on, compressor only on, and both fan and compressor on.

[0053] It should be noted that the equipment vibration status does not refer to the equipment itself containing a compressor or fan, but rather to the equipment being in a refrigeration system. The refrigeration system contains vibrating components such as compressors and fans. These vibrating components can affect the time of equipment that requires clock calibration, and therefore need to be taken into account.

[0054] In other multi-device systems, the vibration state of the equipment can be determined based on the specific vibrating components in the system, such as the vibration state of the equipment when it is turned off or when the motor is turned on.

[0055] By taking the vibration components within the system into account, the clock's factor parameters can be considered more comprehensively.

[0056] In one embodiment, the environmental weight of the device is calculated using the following method.

[0057] Since each device has a different impact on the clock due to its factor parameters, a percentage or scaling factor can be set for each device. These can all be called scaling parameters.

[0058] Multiply the weight corresponding to the factor parameter and the proportion of the factor parameter to obtain the weight ratio of each factor parameter of the device;

[0059] The environmental weight is obtained by summing the weight ratios of all the factor parameters of a device.

[0060] In this embodiment, a proportional parameter is set for each factor parameter, which allows all device factor parameters to be set to the same value. By simply setting the proportional parameter, the influence of the factor parameter on the environmental weight can be adjusted according to the actual situation of the device. This makes the concept of the present invention logically simpler and more flexible when implemented using computer language.

[0061] In one embodiment, at the start of the initial automatic calibration in a multi-device system, any one of the devices initiates a clock calibration request according to a preset transmission interval.

[0062] For example, when there is no historical data on environmental weights, any device can initiate a clock calibration request at a preset sending interval, such as every 30 minutes. The initial automatic calibration start date can be within the first month, the first calibration, or any other period after the start date; the user can define the specific timing. This method is relatively flexible and allows for timely calibration even when historical environmental weight data is lacking.

[0063] In one embodiment, after each clock calibration, the device adjusts the transmission interval for the next clock calibration request based on the deviation between its own time and the average time, and starts timing from zero. The larger the deviation, the greater the adjustment in shortening the transmission interval.

[0064] For example, if a device's time deviates significantly from the average time, the interval between its next clock calibration request needs to be shortened, for instance, to 20 minutes. Other devices, whose times are within the average, can continue using a 30-minute interval. Since the sending intervals are inconsistent, the next time calibration will be based on the shortest interval. To further illustrate with this example, after one time calibration (20 minutes later), the deviation of each device's time from the average time is assessed. If a device with a 20-minute interval still has a significant deviation, its interval can be further reduced. Other devices, whose times are within the average, can maintain a 30-minute interval. At this point, the timer for the next calibration is reset to zero for all devices. This forces inaccurate devices to proactively initiate time calibration to obtain more accurate time, while devices with more accurate clocks generally do not. This allows devices with inaccurate time to calibrate their time promptly based on their specific circumstances.

[0065] In one embodiment, the historical calibration weights of the device are calculated using the following method.

[0066] The theoretical calibration deviation is calculated using the formula △t'=△t2*△ta' / △t1, where △ta' is the deviation during the last calibration, △t1 is the sending interval of the last clock calibration request, and △t2 is the sending interval of the current clock calibration request.

[0067] The corresponding historical calibration weight is determined based on the value of the theoretical calibration deviation.

[0068] For example, a relatively accurate clock device has a deviation of 0 from its last calibration time, so its theoretical calibration deviation is 0, and its historical calibration weight can be set to a maximum value. Conversely, a relatively inaccurate device has a deviation of 20 seconds from its last calibration time. If the last clock calibration request was sent at an interval of 10 minutes and the current clock calibration request is sent at an interval of 8 minutes, then the theoretical calibration deviation Δt' = 20 * 10 / 8 = 25, which is a relatively large value. Therefore, its historical calibration weight can be set relatively low, for example, to 0, which means that the device's clock accuracy is low, so that the specific time value of its clock has no or almost no impact on the average time.

[0069] In other embodiments, the theoretical calibration deviation can also be calculated using the number of times the device is calibrated. However, compared to the previous embodiment, this embodiment can obtain a more accurate theoretical calibration deviation for the device with the least accurate time, while it is difficult to obtain a relatively accurate theoretical calibration deviation for other devices. It is only applicable to certain situations.

[0070] In one embodiment, the time accuracy of the device is calculated by multiplying the device’s environmental weights by its historical calibration weights.

[0071] When the time accuracy of a device is calculated by multiplying the device's environmental weight by its historical calibration weight, it can be ensured that the time of an inaccurate device has no impact on the average time.

[0072] It should be noted that the time accuracy is calculated by multiplying the environmental weight and the historical calibration weight of the equipment. This includes both the time accuracy being equal to the environmental weight multiplied by the historical calibration weight, and further variations based on the environmental weight multiplied by the historical calibration weight, such as multiplying the environmental weight by the historical calibration weight and then multiplying by or adding a correction factor. All of these are calculated by multiplying the equipment's environmental weight and the historical calibration weight.

[0073] During a calibration process, if the time accuracy of a device that exceeds a preset percentage threshold falls below a preset accuracy, the user will be prompted to manually calibrate the time, and the system will broadcast this to other devices to synchronize their device time.

[0074] For example, if more than half of the devices have a time accuracy of 0, the system prompts the user to manually calibrate the time and broadcasts this to other devices for system time synchronization. Specific preset percentage thresholds and preset accuracy can be set according to actual needs. This prevents the system's self-calibration from accumulating errors over time. Therefore, appropriately introducing manual calibration can reduce the continued accumulation of clock errors across system devices. Furthermore, since the system can perform automatic calibration within a certain period, it also reduces the workload for human operators.

[0075] The various non-parallel embodiments of the present invention can be flexibly combined by those skilled in the art to form technical solutions suitable for corresponding scenarios, thereby solving the problem of automatic clock calibration in multi-device systems without network connectivity.

[0076] This invention also protects a multi-device system comprising devices connected via a bus, each device including a control module and a clock module, wherein the control module of each device calibrates the time of its clock module using the clock calibration method for a multi-device system without network connectivity described above.

[0077] The inventive concept of the present invention will now be described in detail with reference to the accompanying drawings and a preferred embodiment.

[0078] The multi-device system of the present invention includes various devices connected by a bus. Each device has no network connectivity, but it can form a local area network system on its own. The devices can communicate with each other to achieve time information sharing and collaborative calibration, thereby improving the overall time accuracy of the system.

[0079] Figure 2 A general structural block diagram of the device is shown.

[0080] Each device is equipped with an independent real-time clock (RTC) module, a microcontroller, a communication module with a communication interface (such as RS-485, CAN bus, or HBS bus), an environmental acquisition module with environmental sensors (temperature and humidity sensors, vibration sensors, etc.), a user interaction module, and a storage module. Each device is assigned a unique device ID in the local area network and has a "time synchronization enable bit" set. Users can enable or disable the automatic calibration function by setting this time synchronization enable bit. Of course, the time synchronization enable bit can also be left unset, in which case all devices will participate in automatic calibration.

[0081] When the time synchronization enable bit is present, after the device's time synchronization enable bit is turned on, the device initially sends a "time calibration request" to the communication bus at a preset period (e.g., every 30 minutes). Since all devices have the same preset period in the initial stage, only one device needs to actively send a time calibration request. After receiving the time calibration request, the other devices send back their current time and time accuracy information. Multiple terminal devices do not depend on a master-slave relationship; they are independent and equal, and achieve time information exchange and collaborative calibration through the communication network.

[0082] A comprehensive evaluation is conducted based on the temperature, humidity, vibration, electromagnetic interference, and cumulative operating time of the equipment's environment. Time accuracy is introduced to indicate the reliability of the equipment's current time.

[0083] In this embodiment, the device's factor parameters include ambient temperature, ambient humidity, device vibration status, device electromagnetic interference status, and device component aging status.

[0084] Regarding ambient temperature and humidity, the equipment collects the temperature and humidity data of its surroundings and, combined with the temperature and humidity characteristic curve of the crystal oscillator, determines the deviation coefficient of the equipment under the ambient temperature and humidity, and then assigns weight levels, such as... Figure 3 , Figure 4 As shown, Figure 3 The weight level X1 corresponding to different ambient temperature ranges is shown. Figure 4 The graph shows the weight level X2 corresponding to different environmental humidity ranges. It can be seen from the graph that excessively high or low temperatures and humidity significantly affect the crystal oscillator of the device, resulting in a lower environmental weight value.

[0085] Regarding the vibration status of the equipment, the vibration and / or noise generated by the system can be tested and evaluated before leaving the factory, and the vibration status can be evaluated based on the equipment's operating status.

[0086] The system in this embodiment takes a refrigeration system as an example. See Figure 5 , Figure 5 The diagram illustrates several equipment vibration states of the refrigeration system, including system shutdown, system with only the fan on, system with only the compressor on, and system with both the fan and compressor on.

[0087] The vibration is smallest when the machine is off, so it has a larger weight. When both the fan and compressor are on, the vibration is the largest, so the weight X3 is smaller.

[0088] Regarding the electromagnetic interference status of equipment, the electromagnetic interference intensity of the corresponding components of the system can be evaluated by testing before leaving the factory, and the interference level can be classified according to the type of the corresponding components in the system (such as fixed frequency / variable frequency) and the operating status (such as power off / power on).

[0089] like Figure 6As shown in the figure, several electromagnetic interference states of the equipment are divided into three categories: off, on (fixed frequency), and on (variable frequency). The electromagnetic interference is the least when the equipment is off, so the weight X4 is larger.

[0090] For the aging status of equipment components, the equipment can record its cumulative operating time t. Aging weights are then assigned based on the corresponding time intervals.

[0091] like Figure 7 As shown, Figure 7 The cumulative running time is divided into four intervals. The shorter the cumulative running time, the greater the weight multiplied by 5.

[0092] The above-mentioned factor parameters take into account various factors in the environment of the refrigeration system that may affect the crystal oscillator. However, different systems and devices operate in different environments; therefore, the proportions of these factor parameters may vary. For example... Figure 8 As shown, Figure 8 The diagram shows the proportional coefficients for each factor parameter of the refrigeration system. Taking the calculation of the environmental weight of one device as an example, the environmental weight of a device can be obtained by multiplying the weights Xi of each dimension by the proportional coefficient αi.

[0093] In addition to the environmental weight of the equipment, the historical calibration weight of the equipment is also important. The equipment records the previous calibration deviation △ta' and transmission interval △t1. Combined with the transmission interval △t2 of the current calibration, the theoretical calibration deviation △t' = △t2*△ta' / △t1 is calculated. The weight level is divided based on the specific value of the theoretical calibration deviation.

[0094] See Figure 9 , Figure 9 This shows that when the deviation is too large or too small, it will lead to a lower weight level, thereby reducing the impact of the corresponding device's time anomaly on the average time.

[0095] Finally, by combining environmental weights and historical calibration weights, the time accuracy is calculated using the formula TD = W. env *W history , where W history This refers to the weight level value corresponding to the historical calibration weight in Figure 9.

[0096] like Figure 11 As shown, when a device initiates a clock calibration request, each device calculates its time accuracy and obtains its own time to send to other devices. Each device can collect the time information of all devices, namely the current time and time accuracy.

[0097] See Figure 10 , Figure 10This illustration shows information collected by each device from all devices in one embodiment. Based on this device information, a formula can be used to... Calculate the average time.

[0098] The time of each device (local time) compared with the average time T arg If a deviation exists, the time will be calibrated to the average time T. arg Simultaneously, based on the time of each calibration and the average time T... arg The deviation is adjusted by setting a preset calibration request interval; the larger the deviation, the shorter the preset calibration request interval.

[0099] Multiple devices exchange time information (including time and time accuracy "TD value") through a communication network. The devices are independent and equal, without relying on a master-slave relationship. By using environmental weights and historical calibration weights, the impact of the environment on time reliability is weakened, some devices with abnormal time are eliminated, and the overall calibration accuracy is guaranteed.

[0100] Once calibration is complete, a calibration completion flag is sent to notify other devices that calibration has been completed. When all devices have completed calibration, this round of automatic time calibration is complete.

[0101] If the time accuracy of more than half of the devices in the system is 0%, a "Time Anomaly" prompt will be triggered, reminding the user to manually calibrate the time via pop-ups, time flashing, or other means. When a device successfully calibrates its time manually, it immediately sends its calibrated time and sets a manual calibration flag. Upon receiving the flag, other devices immediately synchronize their calibrated times. This ensures that even devices located in corners or on balconies can calibrate their times promptly, preventing excessive clock deviations due to user forgetfulness and ensuring accurate timekeeping for the user, thus improving the user experience. Through clock synchronization, users only need to calibrate one device, and the others will automatically calibrate, eliminating the need for individual settings and enhancing the user experience.

[0102] This invention achieves high-precision, decentralized clock calibration by dynamically evaluating time accuracy weights based on device environment and historical calibration data through inter-device communication and time information exchange, employing a "weighted average method" to avoid the risks of relying on a single time source. It constructs a distributed collaborative calibration network where each device is independent and equal; even if some devices experience time anomalies, the overall calibration accuracy is guaranteed through a weighted filtering mechanism. The system dynamically adjusts the calibration request interval based on calibration deviations, improving system response efficiency. Finally, it optimizes the user experience by synchronizing abnormal status prompts with manual calibration, achieving "one manual calibration, automatic synchronization across the entire network."

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A clock calibration method for a multi-device system without network connectivity, characterized in that, include: When a device initiates a clock calibration request, each device obtains the values ​​of factor parameters that affect the clock. Calculate the environmental weight of the device clock based on the values ​​of the factor parameters and their corresponding weights; Each device calculates its time accuracy based on its clock's environmental weight and historical calibration weight, and sends its own time and time accuracy to other devices in the system; Each device calculates the average time based on the time of all devices and the time accuracy, and determines whether its own time deviates from the average time. If so, it adjusts its own time to the average time.

2. The clock calibration method for a multi-device system without network connectivity as described in claim 1, characterized in that, The factor parameters include at least one of the following: ambient temperature, ambient humidity, equipment vibration status, equipment electromagnetic interference status, and equipment component aging status.

3. The clock calibration method for a multi-device system without network connectivity as described in claim 2, characterized in that, When the multi-device system is a refrigeration system, the vibration state of the equipment includes at least one of the following: shutdown, only fan on, only compressor on, and both fan and compressor on.

4. The clock calibration method for a multi-device system without network connectivity as described in claim 1, characterized in that, The environmental weight of the device is calculated using the following method: Multiply the weight corresponding to the factor parameter and the proportion of the factor parameter to obtain the weight ratio of each factor parameter of the device; The environmental weight is obtained by summing the weight ratios of all the factor parameters of a device.

5. The clock calibration method for a multi-device system without network connectivity as described in claim 1, characterized in that, When the initial automatic calibration begins in the multi-device system, any one of the devices initiates a clock calibration request according to a preset transmission interval.

6. The clock calibration method for a multi-device system without network connectivity as described in claim 5, characterized in that, After each clock calibration, the device adjusts the sending interval of the next clock calibration request based on the deviation between its own time and the average time, according to the sending interval of the previous clock calibration request, and starts timing from zero.

7. The clock calibration method for a multi-device system without network connectivity as described in claim 6, characterized in that, The historical calibration weight of the device is calculated using the following method: the theoretical calibration deviation is calculated according to the formula △t'=△t2*△ta' / △t1, where △ta' is the deviation at the last calibration, △t1 is the sending interval of the last clock calibration request, and △t2 is the sending interval of the current clock calibration request. The corresponding historical calibration weight is determined based on the value of the theoretical calibration deviation.

8. The clock calibration method for a multi-device system without network connectivity as described in claim 1, characterized in that, The time accuracy of the device is calculated by multiplying its environmental weight by its historical calibration weight.

9. The clock calibration method for a multi-device system without network connectivity as described in claim 1, characterized in that, If the time accuracy of a device that exceeds a preset percentage threshold is lower than the preset accuracy, the user will be prompted to manually calibrate the time, and the system will broadcast this to other devices to synchronize their device time.

10. A multi-device system comprising devices connected via a bus, each device including a control module and a clock module, characterized in that, The control module uses the clock calibration method for a multi-device system without network connectivity as described in any one of claims 1 to 9 to calibrate the time of its clock module.

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