Intelligent Temperature Control Method and Device for Foot Bath Bucket Based on Multimodal Sensing

Abstract

This invention relates to the field of intelligent temperature control technology for foot bath tubs, specifically, to an intelligent temperature control method and device for foot bath tubs based on multimodal sensing. It includes the following steps: collecting initial foot skin surface temperature of the user, water temperature, pressure signal, ambient temperature, and water level data within the foot bath tub; calculating the temperature difference based on the initial foot skin surface temperature and water temperature; determining whether the user is in the foot-in and foot-out state through pressure signal and water level changes; and calculating the total system heat demand power of the foot bath tub by combining ambient temperature, water level data, and temperature difference; and dynamically generating temperature control commands based on the temperature difference, foot-in and foot-out state, and the corrected total system heat demand power. This invention, by integrating multimodal sensing data such as a flexible temperature sensor array, pressure distribution array, water level, and ambient temperature, enables the system to not only accurately obtain the initial temperature difference between the user's foot skin and the water, but also to combine contact effectiveness analysis and a dynamic weighted algorithm.

Description

Technical Field

[0001] This invention relates to the field of intelligent temperature control technology for foot bath tubs, and more specifically, to an intelligent temperature control method and device for foot bath tubs based on multimodal sensing. Background Technology

[0002] With the popularization of healthy living concepts, smart foot baths have been widely used as home health and wellness devices. However, existing foot bath temperature control technology still has many shortcomings, making it difficult to meet users' comprehensive needs for comfort, safety, and energy efficiency. Traditional foot baths typically rely on a single water temperature sensor for feedback control, employing a simple "set-heat-maintain" logic, ignoring the fact that the actual perceived temperature of the human body is affected by multiple factors such as the initial skin temperature of the feet, the state of immersion in water, ambient temperature, and water volume. For example, if a user's feet are cold when they enter the water, even if the water temperature has reached the set value, it will still feel too cold; and if the system continues to heat after the feet are removed, it not only wastes energy but may also cause the water temperature to be too high for the next use, posing a risk of burns. In addition, existing devices generally lack the ability to intelligently recognize the user's foot entry and exit behavior, failing to dynamically determine the usage status, resulting in problems such as delayed heating response, high ineffective energy consumption, and rigid control strategies. Meanwhile, traditional methods fail to consider the impact of water level changes on the water's heat capacity and heat dissipation area, and also fail to incorporate the human body as a dynamic heat load into the system's thermal balance model. This leads to inaccurate heat demand estimations and is prone to phenomena such as slow heating, temperature overshoot, or large fluctuations. In summary, existing technologies, due to their single sensing dimension, static control logic, and lack of comprehensive understanding of the interaction between "human-water-environment," struggle to achieve precise, comfortable, and energy-efficient intelligent temperature control. Therefore, this paper provides an intelligent temperature control method and device for foot bath tubs based on multimodal sensing. Summary of the Invention

[0003] The purpose of this invention is to provide a smart temperature control method and device for foot bath tubs based on multimodal perception, so as to solve the problems mentioned in the background art, such as inaccurate temperature control, poor comfort, high energy consumption and safety hazards caused by the single perception dimension, lack of user status recognition and dynamic thermal demand modeling of traditional foot bath tubs.

[0004] To achieve the above objectives, the present invention aims to provide an intelligent temperature control method for foot bath tubs based on multimodal sensing, comprising:

[0005] S1. Collect the user's initial foot skin surface temperature, water temperature, pressure signal, ambient temperature and water level data in the foot bath tub;

[0006] S2. By measuring pressure signals and water level changes, determine whether the user is in the foot-in and foot-out state. Calculate the temperature difference based on the user's initial foot skin surface temperature and water temperature, and combine the ambient temperature, water level data, and temperature difference to calculate the total system heat demand power of the foot bath tub.

[0007] In the process of calculating the total heat demand power of the system, the total heat demand power of the system is corrected by combining the water level height with the geometric structural parameters of the foot bath tub.

[0008] S3. Based on the temperature difference, the status of the input and output pins, and the corrected total system heat demand power, dynamically generate temperature control commands;

[0009] S4. Adjust the water temperature in the foot bath tub in real time based on temperature control commands.

[0010] As a further improvement to this technical solution, step S2, which calculates the temperature difference based on the user's initial foot skin surface temperature and the water temperature, includes the following steps:

[0011] S2.1. The initial skin surface temperature of the user's feet and the water temperature are preprocessed, and the effectiveness of the contact surface between the user's feet and the sensor is analyzed and dynamically weighted to generate an effective initial skin surface temperature of the user's feet. The initial skin surface temperature of the user's feet is collected using a flexible temperature sensor array.

[0012] S2.2, Preset the highest temperature threshold that the human body can withstand;

[0013] S2.3. Based on the initial foot skin surface temperature of the effective user and the water temperature, calculate the difference between the water temperature and the initial foot skin surface temperature of the effective user to obtain the initial temperature difference sequence.

[0014] As a further improvement to this technical solution, in step S2.1, the effectiveness analysis and dynamic weighting of the contact surface between the foot and the sensor are performed, including the following steps:

[0015] The area covered by the flexible temperature sensor array is logically divided into N independent sensing units;

[0016] Data from each sensing unit is processed in parallel. For a single sensing unit... Synchronously read its temperature value and its corresponding pressure value and the sensing unit Perform a validity assessment;

[0017] If the sensing unit If a contact unit is valid, it is marked as a valid contact unit. The temperature readings of all marked valid contact units are then compiled, and the pressure value of each valid unit is used as the basis for the calculation. Calculate its weight;

[0018] Based on weight Calculate the effective surface temperature of the foot skin.

[0019] As a further improvement to this technical solution, in step S2, determining whether the user is in the foot-in or foot-out state based on pressure signals and water level changes includes the following steps:

[0020] S2.4 Preprocess the pressure signal and water level data;

[0021] S2.5 Record the pressure baseline and water level baseline when the tank is empty;

[0022] S2.6 Calculate the change in pressure relative to the baseline and the change in water level relative to the baseline, and simultaneously calculate the rate of change of pressure and water level within the time window T;

[0023] S2.7 When the combined changes in pressure and water level relative to the baseline satisfy the initial threshold conditions for the inlet and outlet, a continuous trigger is activated. The thermal inertia verification window is set up, and the water temperature at the trigger moment is recorded.

[0024] S2.8. Collect water temperature sequence within the thermal inertia verification window, perform thermodynamic consistency verification on the preliminary threshold conditions, and output user ingress and egress action status signals.

[0025] As a further improvement to this technical solution, in S2.8, thermodynamic consistency verification is performed on the preliminary threshold condition, specifically as follows:

[0026] Calculate the slope of the change in water temperature within the thermal inertia verification window. ;

[0027] For the initial threshold condition that preliminarily determines a foot to be exited, if the slope The slope of the positive threshold for the exit judgment is greater than the threshold slope. If the user state is determined to be a foot action event, then the user state is determined to be a non-foot action event.

[0028] For the initial threshold condition that preliminarily determines a foothold, if the slope The slope of the negative threshold for the footer determination is less than the threshold slope. If the user state is determined to be a footstep action event, then the user state is determined to be a non-footstep action event.

[0029] As a further improvement to this technical solution, step S2, which combines ambient temperature, water level data, and temperature difference to calculate the total system heat demand power of the foot bath tub, includes the following steps:

[0030] S2.9 Preprocess the ambient temperature and water level data;

[0031] S2.10. Based on the water level and the geometric parameters of the foot bath tub, the surface area and effective heat capacity of the water body are corrected to reflect the actual impact of water level changes on heat loss.

[0032] S2.11. Calculate the ambient heat loss power using a comprehensive model based on Newton's law of cooling;

[0033] S2.12 Calculate the user's heat load power based on the temperature difference between the user's initial foot skin surface temperature and the water temperature;

[0034] S2.13. Combine the environmental heat loss power and the user heat load power to generate the total system heat demand power.

[0035] As a further improvement to this technical solution, in step S2.10, the surface area and effective heat capacity of the water are corrected based on the water level and the geometric parameters of the foot bath tub, including the following steps:

[0036] Real-time acquisition of current water level and collection of geometric parameters of foot bath tub;

[0037] The corrected water surface area is calculated based on the convective radiation area between the water surface and the air, and the conduction area between the barrel wall below the water level and the environment.

[0038] The corrected effective heat capacity is calculated based on the current water level.

[0039] As a further improvement to this technical solution, step S3, dynamically generating temperature control commands, includes the following steps:

[0040] S3.1. The highest temperature threshold that the human body can withstand, the foot entry and exit action states, and the system heat loss power are uniformly time-aligned and feature-fused to form a set of input parameters.

[0041] S3.2 Compare the current water temperature with the preset maximum temperature threshold a that the human body can withstand;

[0042] S3.3. Constrain control commands based on the input and output pin states;

[0043] S3.4. Based on the current water temperature difference and the total heat demand of the system, and combined with the corrected effective heat capacity, generate a dynamic heating power command, and implement anti-scalding mode and safety threshold control.

[0044] As a further improvement to this technical solution, step S4 involves real-time adjustment of the water temperature in the foot bath tub based on temperature control commands, including the following steps:

[0045] S4.1 The temperature control command is sent to the heating execution unit in real time, and the power of the heater is adjusted using the temperature control command;

[0046] S4.2 After the temperature control command is completed, the current water temperature is re-acquired, and the ambient temperature, pressure signal and water level data are collected simultaneously. The newly acquired water temperature is compared with the target water temperature, the new temperature difference error is calculated, and the temperature of the water in the foot bath bucket is adjusted in real time in combination with the foot inlet and outlet status and the total heat demand power of the system.

[0047] On the other hand, the present invention provides a smart temperature control device for a foot bath tub based on multimodal perception, including a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor executes the computer program to implement the above-mentioned smart temperature control method for a foot bath tub based on multimodal perception.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] 1. In this invention, by integrating multimodal sensing data such as flexible temperature sensor arrays, pressure distribution arrays, water level, and ambient temperature, the system can not only accurately obtain the initial temperature difference between the user's foot skin and the water, but also realistically reproduce the user's perceived temperature by combining contact effectiveness analysis and dynamic weighting algorithms. Based on this, using a foot-in / foot-out state recognition mechanism and thermodynamic consistency verification, the system accurately determines the user's behavioral intent and dynamically calculates the total system heat demand power, including environmental heat loss and human body heat load. Combined with an improved PID control strategy and safety protection logic (such as anti-scalding mode and overheating rate protection), the system achieves adaptive adjustment of heating power, quickly responding to temperature differences while avoiding overheating or scalding risks, thus providing a stable, comfortable, and safe foot bath experience in different usage scenarios.

[0050] 2. In this invention, by real-time correction of the water surface area and effective heat capacity related to the water level, and based on this, accurately modeling the environmental heat loss power, the system can dynamically adjust the heating strategy according to the actual water volume, avoiding the energy waste caused by traditional constant power heating. Specifically, after detecting the user's foot leaving the water, the system automatically switches to energy optimization mode, compensating only for environmental heat loss and significantly reducing ineffective energy consumption; while when the foot re-enters the water, it actively enhances compensatory heating, shortening the waiting time for temperature rise. This closed-loop energy control mechanism based on multi-source sensing and state recognition not only improves energy utilization efficiency but also reduces frequent heater start-ups and overload operations, helping to extend the service life of heating elements and control systems, achieving a dual improvement in green environmental protection and equipment durability. Attached Figure Description

[0051] Figure 1 This is a flowchart of the overall method of the present invention. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0053] Example 1: Please refer to Figure 1 As shown, this embodiment provides a smart temperature control method for foot bath tubs based on multimodal sensing, including the following steps:

[0054] S1. Collect the user's initial foot skin surface temperature in the foot bath tub (collect temperature distribution data of the foot area through a high-resolution flexible temperature sensor array, not just a single point; here only the instantaneous skin temperature of the user's feet after entering the water is collected to obtain the initial temperature of the user's foot skin after entering the water), water temperature (collected through a waterproof temperature sensor (such as RTD, thermocouple or digital temperature sensor)), pressure signal (collected through a pressure distribution array corresponding to the temperature array), ambient temperature (ambient temperature is collected through an air temperature sensor), and water level data (water level data is collected through a liquid level sensor or an ultrasonic / pressure water level sensor).

[0055] S2. By measuring pressure signals and water level changes, determine whether the user is in the foot-in and foot-out state. Calculate the temperature difference based on the user's initial foot skin surface temperature and water temperature, and combine the ambient temperature, water level data, and temperature difference to calculate the total system heat demand power of the foot bath tub.

[0056] In the process of calculating the total heat demand power of the system, the total heat demand power of the system is corrected by combining the water level height with the geometric structural parameters of the foot bath tub.

[0057] In this embodiment, the temperature difference is calculated based on the user's initial foot skin surface temperature and the water temperature, including the following steps:

[0058] S2.1. Preprocess the collected initial user foot skin surface temperature and water temperature (synchronize the collected initial user foot skin surface temperature signal and water temperature signal in time, and smooth the sampled data by moving average or Kalman filtering to remove occasional noise and outliers and obtain a reliable temperature sequence), and perform validity analysis and dynamic weighting on the contact surface between the user's foot and the sensor to generate a valid initial user foot skin surface temperature. The initial user foot skin surface temperature is collected using a flexible temperature sensor array. This step is only performed once after the foot is determined to be valid.

[0059] Furthermore, an effectiveness analysis and dynamic weighting of the contact surface between the foot and the sensor are performed, including the following steps:

[0060] The area covered by the flexible temperature sensor array is logically divided into N independent sensing units;

[0061] Data from each sensing unit is processed in parallel. For a single sensing unit... Synchronously read its temperature value and its corresponding pressure value and the sensing unit Perform a validity assessment, if Greater than the preset pressure threshold, and If the temperature is within a preset reasonable skin temperature range (e.g., 25℃-42℃) and there is a significant temperature difference between the skin temperature and the water temperature, then the sensing unit is considered to be... For an effective contact unit, if Too low or If there is an anomaly (close to water temperature or ambient temperature), the sensing unit is identified as abnormal. This is an invalid contact unit (possibly not in contact or with poor contact);

[0062] If the sensing unit If a contact unit is valid, it is marked as a valid contact unit. The temperature readings of all marked valid contact units are then compiled, and the pressure value of each valid unit is used as the basis for the calculation. Calculate its weight : In the formula, The total number of effective contact units represents the total number of contact units. Higher pressure indicates tighter contact, more reliable temperature measurement, and a higher weighting. For the first Pressure value of each effective contact unit For the indices of all valid contact elements used for summation, The index of the valid contact unit whose weight is currently being calculated;

[0063] Based on weight Calculate the effective surface temperature of the foot skin : .

[0064] S2.2, Preset the highest temperature threshold that the human body can withstand, a.

[0065] S2.3. Based on the initial foot skin surface temperature of the effective user and the water temperature, calculate the difference between the water temperature and the initial foot skin surface temperature of the effective user to obtain the initial temperature difference sequence, i.e., the temperature difference. The temperature difference here is only used to calculate the total heat demand of the foot bath system. If the temperature difference is too large, it means that the user may feel uncomfortable (the water is too cold or too hot). Step S3 can adjust the power more aggressively to quickly reduce the temperature difference and improve comfort. However, the ultimate goal is still to reach the target water temperature. If the water temperature has reached the target water temperature but the temperature difference is still large, it may mean that the sensor is faulty or the user has just put their feet in. The system can determine whether to continue high-power heating based on this.

[0066] Furthermore, by analyzing pressure signals and water level changes, it is determined whether the user is in the foot-in or foot-out state, including the following steps:

[0067] S2.4 Preprocess the pressure signal and water level data, including time synchronization, filtering, baseline and calibration (maintain short-term baselines for pressure and water level in real time (such as the median of the last 60 seconds) for adaptive thresholding and drift compensation).

[0068] S2.5 Record the pressure baseline and water level baseline when the tank is empty.

[0069] S2.6 Calculate the change in pressure relative to the baseline and the change in water level relative to the baseline, and simultaneously calculate the rate of change of pressure and water level within a short time window T.

[0070] S2.7 When the combined changes in pressure and water level relative to the baseline satisfy the preliminary threshold conditions for both the ingress and egress points (when the system monitors significant changes in both pressure and water level relative to the baseline in real time, if the change in pressure relative to the baseline increases and the water level rises simultaneously, exceeding the ingress threshold condition, it is initially determined to be a user ingress point; conversely, if the change in pressure relative to the baseline decreases and the water level falls simultaneously, exceeding the egress threshold condition, it is initially determined to be a user egress point. This determination serves as the trigger condition for proceeding to subsequent thermal inertia verification), a continuous... A thermal inertia verification window (e.g., 30 seconds) is established, and the water temperature at the trigger moment is recorded. This triggers a continuous... The thermal inertia verification window (e.g., 30s) refers to the system not making a final judgment immediately after detecting that the initial conditions for user entry or exit are met. Instead, it opens a verification period of fixed duration (e.g., 30 seconds) during which water temperature data is continuously collected at a high frequency to observe whether the temperature change trend (heating or cooling) is consistent with the physical thermal effect of entry or exit.

[0071] S2.8. High-frequency acquisition of water temperature sequence within the thermal inertia verification window, thermodynamic consistency verification of preliminary threshold conditions, and output of user ingress and egress action status signals.

[0072] Among them, thermodynamic consistency verification of the preliminary threshold conditions is a specific issue concerning how to accurately distinguish between real user foot-entry / foot-exit actions and interference signals (such as slight user touch of the bucket wall, water level fluctuations, or other false positive signals caused by non-foot intervention) in application scenarios of the intelligent temperature control method for foot bath buckets based on multimodal perception. This verification step monitors the slope of water temperature change after triggering the initial threshold. Utilizing the thermodynamic characteristics of rapid temperature drop upon foot entry and slow temperature recovery upon foot exit, it performs secondary confirmation of the action event. This avoids misjudgment leading to malfunctions in the control system (such as overheating upon foot entry or stopping heating upon foot exit), improving the reliability of status recognition. This method overcomes the limitations of traditional single-sensor (such as relying solely on water level or pressure switches) judgments, which are susceptible to interference, through cross-verification of multimodal signals (pressure, water level) and thermodynamic behavior (water temperature change inertia). This significantly improves the accuracy and robustness of action status recognition. Simultaneously, this verification mechanism allows for high sensitivity in the initial threshold setting (accepting false positives), and further eliminates false alarms through thermal inertia verification. This ensures the system's potential for rapid response to user actions while avoiding energy waste or decreased comfort due to false triggering, achieving a balance between response speed and accuracy.

[0073] Thermodynamic consistency verification of the initial threshold conditions is performed, specifically as follows:

[0074] Calculate the slope of the change in water temperature within the thermal inertia verification window. ;

[0075] For the initial threshold condition that preliminarily determines a foot to be exited, if the slope The slope of the positive threshold for the exit judgment is greater than the threshold slope. hour( value ratio Because the water temperature recovery is achieved through heating by the heater or natural recovery, the process is relatively slow. It can be set to 0.03~0.08°C / s (i.e., a slope greater than +0.05°C / s is considered valid). If the user state is determined to be a foot action event (i.e., a valid foot action), it is used to control the state output. Otherwise, the user state is determined to be a non-foot action event, and the current control state is not changed.

[0076] For the initial threshold condition that preliminarily determines a foothold, if the slope The slope of the negative threshold for the footer determination is less than the threshold slope. hour( Experiments show that the water temperature drop rate when the user steps in is usually above -0.2°C / s. Therefore, the threshold can be set to 0.1~0.15°C / s (i.e., a slope less than -0.1°C / s is considered valid). This will determine the user's state as a step-in action event (i.e., a valid step-in) and be used to control the state output. Otherwise, the user's state will be determined as a non-step-in action event (e.g., the user just touched the bucket wall), and the current control state will not be changed.

[0077] Furthermore, the total heat demand power of the foot bath tub system is calculated by combining ambient temperature, water level data, and temperature difference, including the following steps:

[0078] S2.9 Preprocess the ambient temperature and water level data (i.e., perform time synchronization and filtering on various types of data to ensure data stability and reliability).

[0079] S2.10. Based on the water level and the geometric parameters of the foot bath tub, the surface area and effective heat capacity of the water body are corrected to reflect the actual impact of water level changes on heat loss and ensure that the impact of water level changes on heat loss is taken into account.

[0080] The correction of water surface area and effective heat capacity addresses the inaccuracy of the thermodynamic model caused by dynamic changes in water volume within the foot bath tub. Traditional temperature control methods typically treat the foot bath tub as a system with fixed parameters (such as fixed water volume and fixed heat dissipation area). However, in actual use, the water level frequently changes due to user foot entry / exit, evaporation, or water addition. These water level changes directly alter the total heat capacity of the water (different energy required to heat to the same temperature) and the heat exchange surface area with the external environment (different heat dissipation rates). If this change is ignored, the system's calculated heat demand power will deviate significantly from reality, leading to inaccurate temperature control, overshoot or lag in response, and energy waste. This method dynamically integrates water level sensor data and tub geometric parameters to accurately calculate the effective heat capacity and heat dissipation surface area of ​​the current water in real time. This allows the heat demand power model to adapt to water level changes, fundamentally improving the system's temperature control accuracy, response speed, and energy efficiency under different water volumes. It represents a leap from "fixed model, coarse control" to "dynamic model, precise compensation."

[0081] Based on the water level and the geometric parameters of the foot bath tub, the water surface area and effective heat capacity are adjusted, including the following steps:

[0082] The current water level height is obtained in real time via a liquid level sensor or a flow / water level measurement module. ( (and collect the geometric parameters of the foot bath tub, including the bottom radius) The shape of the bucket (approximately cylindrical in this embodiment) is used to calculate the surface area and volume of the water.

[0083] The corrected water surface area is calculated based on the convective radiation area between the water surface and the air, and the conduction area between the barrel wall below the water level and the environment.

[0084] The corrected effective heat capacity is calculated based on the current water level.

[0085] In this embodiment, the bottom of the foot bath tub is approximately cylindrical, with a height of [missing information]. , radius is The current water level is ( The density of the water is Specific heat capacity is .

[0086] Corrected water surface area (Including the convective radiation area between the water surface and the air, and the conductive area between the barrel wall below the water level and the environment):

[0087] ;

[0088] In the formula, For water surface area, This refers to the area of ​​the barrel wall below the water level.

[0089] Corrected effective heat capacity for:

[0090] ;

[0091] Among them, the corrected effective heat capacity It can be used to estimate the rate of temperature rise / fall in water, providing a basis for the generation of temperature control commands and closed-loop regulation, thereby ensuring that water temperature changes conform to thermal inertia characteristics;

[0092] According to the above formula, as the water level height is... As the conditions change, the surface area and effective heat capacity of the water body will be dynamically adjusted.

[0093] S2.11 Calculate the ambient heat loss power using a comprehensive model based on Newton's law of cooling. (Heat power lost to the environment through the barrel walls and water surface):

[0094] ;

[0095] In the formula, The comprehensive environmental thermal conductivity coefficient (unit: W / (m²·℃)) reflects the efficiency of heat transfer between water bodies and the environment, including factors such as conduction, convection, and radiation. Its empirical value range is approximately 1.5~10 W / (m²·℃). The current water temperature (unit: °C). The ambient temperature (unit: °C) refers to the temperature of the environment in which the foot bath tub is located. For time.

[0096] S2.12 Calculate the user's heat load power based on the temperature difference between the user's initial foot skin surface temperature and the water temperature: In the formula, The local heat transfer coefficient (unit: W / ℃) between the user's feet and the water body is calculated by comprehensively considering the contact area between the skin and the water body, thermal conductivity, and local thermal resistance. This coefficient is used to convert temperature difference into heat power. For a typical adult foot immersion area of ​​approximately 0.02~0.03 m², considering the range of convective heat transfer coefficients between the skin and water (natural convection is approximately 200~600 W / (m²·℃)), this equivalent coefficient... The typical value range is approximately 4~18 W / ℃. The user's foot contact status signal (dimensionless, usually 0 or 1, or a continuous value of 0 to 1 to indicate the degree of contact, i.e., a floating-point number to represent the degree of contact or the proportion of effective area) is used to determine whether the user's foot is actually in contact with the water: 0: no contact or foot out state, the user's heat load power is 0; 1: effective foot contact state, the user's heat load power is calculated based on the temperature difference and heat transfer coefficient, if it is a continuous value, it indicates the tightness of contact or the proportion of effective area.

[0097] S2.13. Combine the environmental heat loss power and the user heat load power to generate the total system heat demand power. : .

[0098] S3. Based on the temperature difference, the status of the input and output pins, and the corrected total system heat demand power, dynamically generate temperature control commands.

[0099] In this embodiment, dynamically generating temperature control commands includes the following steps:

[0100] S3.1 The maximum tolerable temperature threshold 'a' for the human body, the foot entry and exit action states, and the system's heat loss power are uniformly time-aligned and feature-fused to form the set of input parameters required for temperature control decisions; the target water temperature desired by the user is then set. This value can be set by the user through the interactive interface, or it can be automatically determined by the system according to preset modes (such as sleep aid mode or cold-dispelling mode).

[0101] S3.2. Compare the current water temperature with the preset maximum temperature threshold a that the human body can withstand (e.g., 42℃). If the water temperature is greater than or equal to the maximum temperature threshold a that the human body can withstand, immediately activate the cooling or power-off protection.

[0102] S3.3. Constrain control commands based on inlet and outlet states. When an inlet state is detected, the system prioritizes increasing the water temperature adjustment response speed, allowing the heating power limit to be increased to a higher range (e.g., 90% of the maximum power), and adjusts the power according to the user's heat load. Enhanced compensatory heating; when a lead-out state is detected, the system reduces the upper limit of heating power and enters energy consumption optimization mode, only compensating for power lost due to ambient heat. To avoid unnecessary energy consumption; when in a steady state (no foot insertion or removal), maintain power based on total heat demand. Steady-state regulation.

[0103] S3.4. Based on the current water temperature difference and the total heat demand of the system, and combined with the corrected effective heat capacity, generate a dynamic heating power command, and implement anti-scalding mode and safety threshold control.

[0104] Among them, dynamic heating power command for:

[0105] ;

[0106] In the formula, This represents the current temperature difference error (unit: °C). This represents the difference between the real-time water temperature and the target water temperature. A positive difference indicates that the water temperature is lower than the target temperature and heating is required; a negative difference indicates that the water temperature is higher than the target temperature and heating power needs to be reduced or stopped. This is a proportionality coefficient (dimensionless or in units of W / ℃), used to directly calculate the proportional power correction based on the current temperature difference error. It has a fast response but may have steady-state errors. This is the integral coefficient (unit: W / (°C·s)), used to accumulate the sum of past temperature difference errors, compensate for long-term deviations, and eliminate steady-state errors. The differential coefficient (unit: W·s / ℃) is used to predict the trend of temperature difference changes, adjust the power according to the rate of temperature change, improve the system response speed, and suppress overshoot. This is the integral term, which accumulates historical temperature difference errors to adjust for long-term system deviations. The rate of change of temperature (unit: °C / s) reflects the trend of water temperature change and is used for differential adjustment of power.

[0107] In the above formula, the formula parameters ( , , Based on the current effective heat capacity Adaptive adjustment: when water level Lower (effective heat capacity) When the system is small, its inertia is low, and the water temperature changes rapidly; therefore, the proportional coefficient should be reduced. and integral coefficient And increase the differential coefficient When the water level Higher (heat capacity) When the system is large, the system inertia is high and the water temperature changes slowly, so the proportional coefficient should be increased. and integral coefficient This is to accelerate the system's response speed and overcome the lag caused by large inertia.

[0108] The anti-scalding mode and safety threshold control are as follows:

[0109] When the temperature difference between the water and the user's initial foot skin temperature exceeds a safety threshold (e.g., 6°C), the system activates anti-scalding mode, automatically limiting the power output limit (e.g., not exceeding 50% of the maximum power) and shortening the heating time per cycle. Simultaneously, it calculates the water temperature rise rate under unit heating power using the current corrected effective heat capacity, thereby calculating the maximum safe heating time allowed without exceeding the target water temperature or the user's perceived safety threshold (e.g., 42°C). If heating beyond this time is anticipated to cause the water temperature to exceed the safety limit, the system automatically shortens the heating time or reduces the heating power. When the water temperature is detected to exceed the human-tolerable threshold 'a' (e.g., 42°C), an emergency power reduction command is immediately generated. If the water temperature rises too quickly (the slope exceeds the upper limit threshold d, for example, 0.3℃ / s), the over-temperature rate protection is triggered, and the heating power is dynamically reduced by 30%~70%.

[0110] The calculated power command is converted into segmented temperature control commands, including: heating power: setting the target power output percentage of the heater; heating duration: estimating the required heating time window based on the temperature difference and thermal inertia, and executing it in segments to avoid continuous full-power operation for a long time; dynamic mode switching: switching to pulse intermittent heating mode when the water temperature approaches the target value to reduce overshoot.

[0111] S4. Adjust the water temperature in the foot bath tub in real time based on temperature control commands.

[0112] In this embodiment, the real-time control of the water temperature in the foot bath tub includes the following steps:

[0113] S4.1 The temperature control command is sent to the heating execution unit in real time. The power of the heater is adjusted using the temperature control command. Specifically, the target power output is achieved through PWM duty cycle adjustment or graded power switching, and heating continues for the duration set by the command. For commands in normal mode, the heater outputs the calculated power. In anti-scalding mode, the heating power is limited to the safe upper limit, and pulsed time-sharing heating is used to avoid excessive temperature rise. If the system detects an emergency power reduction command, the heating output is immediately cut off, and the system enters a cooling or power-off protection state.

[0114] S4.2 After the temperature control command is completed, the current water temperature is re-acquired, and the ambient temperature, pressure signal, and water level data are collected simultaneously. The collected temperature sequence is filtered to eliminate instantaneous noise and obtain a smoothed, reliable water temperature. The newly acquired water temperature is compared with the target water temperature to calculate the new temperature difference error. Combined with the foot inlet and outlet status and the total system heat demand, the water temperature in the foot bath tub is adjusted in real time. Specifically, the newly acquired water temperature is compared with the preset target water temperature of 40℃ to calculate the new temperature difference error. At the same time, combined with the current user foot inlet or outlet status signal and the total system heat demand, it is determined whether the water temperature has reached the target water temperature. If the temperature difference error is within the allowable range (e.g., ±0.2℃) and the user foot inlet status is valid, the target water temperature is determined to be reached and the heating power is maintained or finely adjusted. If the temperature difference exceeds the allowable range or the user status changes, a new heating control command is dynamically generated based on the magnitude and direction of the temperature difference error and the total system heat demand, realizing closed-loop regulation of the water temperature towards the target point.

[0115] Example 2: This example provides a smart temperature control device for a foot bath tub based on multimodal perception, including a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor executes the computer program to implement the above-mentioned smart temperature control method for a foot bath tub based on multimodal perception.

[0116] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for intelligent temperature control of a foot bath tub based on multimodal sensing, characterized in that, Includes the following steps: S1. Collect the user's initial foot skin surface temperature, water temperature, pressure signal, ambient temperature and water level data in the foot bath tub; S2. By measuring pressure signals and water level changes, determine whether the user is in the foot-in and foot-out state. Calculate the temperature difference based on the user's initial foot skin surface temperature and water temperature, and combine the ambient temperature, water level data, and temperature difference to calculate the total system heat demand power of the foot bath tub. In the process of calculating the total heat demand power of the system, the total heat demand power of the system is corrected by combining the water level height with the geometric structural parameters of the foot bath tub. S3. Based on the temperature difference, the status of the input and output pins, and the corrected total system heat demand power, dynamically generate temperature control commands; S4. Adjust the water temperature in the foot bath tub in real time based on temperature control commands.

2. The intelligent temperature control method for foot bath tub based on multimodal sensing according to claim 1, characterized in that: In step S2, the temperature difference is calculated based on the user's initial foot skin surface temperature and the water temperature, including the following steps: S2.

1. The initial skin surface temperature of the user's feet and the water temperature are preprocessed, and the effectiveness of the contact surface between the user's feet and the sensor is analyzed and dynamically weighted to generate an effective initial skin surface temperature of the user's feet. The initial skin surface temperature of the user's feet is collected using a flexible temperature sensor array. S2.2, Preset the highest temperature threshold that the human body can withstand; S2.

3. Based on the initial foot skin surface temperature of the effective user and the water temperature, calculate the difference between the water temperature and the initial foot skin surface temperature of the effective user to obtain the initial temperature difference sequence.

3. The intelligent temperature control method for foot bath tub based on multimodal sensing according to claim 2, characterized in that: In step S2.1, the effectiveness analysis and dynamic weighting of the contact surface between the foot and the sensor are performed, including the following steps: The area covered by the flexible temperature sensor array is logically divided into N independent sensing units; Data from each sensing unit is processed in parallel. For a single sensing unit... Synchronously read its temperature value and its corresponding pressure value and the sensing unit Perform a validity assessment; If the sensing unit If a contact unit is valid, it is marked as a valid contact unit. The temperature readings of all marked valid contact units are then compiled, and the pressure value of each valid unit is used as the basis for the calculation. Calculate its weight ; Based on weight Calculate the effective surface temperature of the foot skin.

4. The intelligent temperature control method for foot bath tubs based on multimodal sensing according to claim 2, characterized in that: In step S2, the determination of whether the user is in the foot-in or foot-out state is based on pressure signals and water level changes, including the following steps: S2.4 Preprocess the pressure signal and water level data; S2.5 Record the pressure baseline and water level baseline when the tank is empty; S2.6 Calculate the change in pressure relative to the baseline and the change in water level relative to the baseline, and simultaneously calculate the rate of change of pressure and water level within the time window T; S2.7 When the combined changes in pressure and water level relative to the baseline satisfy the initial threshold conditions for the inlet and outlet, a continuous trigger is activated. The thermal inertia verification window is set up, and the water temperature at the trigger moment is recorded. S2.

8. Collect water temperature sequence within the thermal inertia verification window, perform thermodynamic consistency verification on the preliminary threshold conditions, and output user ingress and egress action status signals.

5. The intelligent temperature control method for foot bath tub based on multimodal sensing according to claim 4, characterized in that: In S2.8, the thermodynamic consistency verification of the preliminary threshold condition is performed, specifically as follows: Calculate the slope of water temperature change within the thermal inertia verification window. ; For the initial threshold condition that preliminarily determines a foot to be exited, if the slope The slope of the positive threshold for the exit judgment is greater than the threshold slope. If the user state is determined to be a foot action event, then the user state is determined to be a non-foot action event. For the initial threshold condition that preliminarily determines a foothold, if the slope The slope of the negative threshold for the ingress determination is less than the threshold slope. If the user state is determined to be a footstep action event, then the user state is determined to be a non-footstep action event.

6. The intelligent temperature control method for a foot bath tub based on multimodal sensing according to claim 4, characterized in that: In step S2, the total heat demand power of the foot bath tub system is calculated by combining ambient temperature, water level data, and temperature difference, including the following steps: S2.9 Preprocess the ambient temperature and water level data; S2.

10. Based on the water level and the geometric parameters of the foot bath tub, the surface area and effective heat capacity of the water body are corrected to reflect the actual impact of water level changes on heat loss. S2.

11. Calculate the ambient heat loss power using a comprehensive model based on Newton's law of cooling; S2.12 Calculate the user's heat load power based on the temperature difference between the user's initial foot skin surface temperature and the water temperature; S2.

13. Combine the environmental heat loss power and the user heat load power to generate the total system heat demand power.

7. The intelligent temperature control method for foot bath tub based on multimodal sensing according to claim 6, characterized in that: In step S2.10, the surface area and effective heat capacity of the water body are corrected based on the water level and the geometric parameters of the foot bath tub, including the following steps: Real-time acquisition of current water level and collection of geometric parameters of foot bath tub; The corrected water surface area is calculated based on the convective radiation area between the water surface and the air, and the conduction area between the barrel wall below the water level and the environment. The corrected effective heat capacity is calculated based on the current water level.

8. The intelligent temperature control method for foot bath tub based on multimodal sensing according to claim 2, characterized in that: In step S3, the dynamic generation of temperature control commands includes the following steps: S3.

1. The highest temperature threshold that the human body can withstand, the foot entry and exit action states, and the system heat loss power are uniformly time-aligned and feature-fused to form a set of input parameters. S3.2 Compare the current water temperature with the preset maximum temperature threshold a that the human body can withstand; S3.

3. Constrain control commands based on the input and output pin states; S3.

4. Based on the current water temperature difference and the total heat demand of the system, and combined with the corrected effective heat capacity, generate a dynamic heating power command, and implement anti-scalding mode and safety threshold control.

9. The intelligent temperature control method for foot bath tub based on multimodal sensing according to claim 1, characterized in that: In step S4, the water temperature in the foot bath tub is adjusted in real time based on temperature control commands, including the following steps: S4.1 The temperature control command is sent to the heating execution unit in real time, and the power of the heater is adjusted using the temperature control command; S4.2 After the temperature control command is completed, the current water temperature is re-acquired, and the ambient temperature, pressure signal and water level data are collected simultaneously. The newly acquired water temperature is compared with the target water temperature, the new temperature difference error is calculated, and the temperature of the water in the foot bath bucket is adjusted in real time in combination with the foot inlet and outlet status and the total heat demand power of the system.

10. A smart temperature control device for a foot bath tub based on multimodal sensing, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: The processor executes a computer program to implement the intelligent temperature control method for foot bath tubs based on multimodal perception as described in any one of claims 1-9.

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