Traditional Chinese medicine low-temperature belt type drying control system and control method

Abstract

The invention relates to the technical field of traditional Chinese medicine drying process automatic control, and discloses a traditional Chinese medicine low-temperature belt type drying control system and method. A closed-loop control strategy integrating multi-point moisture sampling, trend analysis, target and fluctuation control, temperature feedforward, belt speed feedback, vacuum collaboration, stability criterion freezing and tail detection archiving is provided. A plurality of sampling points are arranged along the conveying belt, moisture is monitored in real time, and time sequence differential analysis is combined, so that static moisture content deviation is captured, the drying rate and trend are sensed dynamically, and multi-channel coordinated adjustment of temperature, belt speed and vacuum is achieved. The system is provided with a safety boundary and a minimum resolution, and it is guaranteed that control operation can be executed and is accurate. The stable interval criterion effectively avoids frequent invalid adjustment, and the tail multi-point detection and whole-course data archiving provide a solid basis for quality tracing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automatic control of traditional Chinese medicine drying process, in particular to a low-temperature belt drying control system and method for traditional Chinese medicine. BACKGROUND

[0002] Traditional Chinese medicinal materials and their tonifying preparations are highly sensitive to temperature, vacuum degree and time during the drying process. Slight improper operation may cause loss of volatile components, degradation of polysaccharide / saponin activity, or excessive residual moisture leading to mold growth and storage risks. Low-temperature belt drying equipment has become one of the main drying methods for valuable traditional Chinese medicines due to its continuous operation, strong controllability and gentle heating of materials. This type of equipment usually operates under vacuum conditions. Wet materials are evenly distributed on the conveying belt by the material distribution device. The materials move along the belt and obtain heat through conduction and radiation between the heating plate and the conveying belt. The internal moisture of the materials is evaporated and removed by the vacuum pump. When the materials reach the discharge end, the cutting device removes them, and the finished products are obtained after crushing. This process involves heat transfer, mass transfer and phase equilibrium changes, and is a typical complex process industrial control object with multiple variables, strong coupling, nonlinearity and time delay.

[0003] Existing production practices generally rely on empirical setting or conventional modular combined control (such as fixed temperature rising curve combined with segmented setting of belt speed and vacuum degree), and some use proportional-integral-derivative adjustment, fuzzy rules or predictive control based on mechanism / experience model. However, for the quality target of valuable traditional Chinese medicines that "the average final moisture content and the within-batch standard deviation are simultaneously constrained", these methods still have common bottlenecks: first, the lag. Online measurement of moisture content usually relies on infrared or near-infrared methods. The signal needs to be sampled and estimated to reflect the actual moisture change, resulting in a lag in the response of the adjustment action to the "trend", which is prone to overshoot or under-drying. Second, coupling is difficult to solve. The heating plate temperature, the conveying belt speed and the vacuum volume flow all affect the evaporation driving force and the residence time. Traditional single-loop or weakly coupled strategies cannot balance the average moisture and spatial uniformity. Third, the parameters depend on experience. A large number of methods require manual tuning of gains, weights and safety factors, which have poor parameter portability, insufficient batch consistency, and difficulty in forming deterministic traceable basis. Fourth, spatial non-uniformity. The thickness of the material, the difference in heat exchange at the edge and the local accumulation can cause the moisture content on the belt surface to be dispersed. The conventional adjustment driven by "global mean error" cannot directly suppress the standard deviation, resulting in excessive fluctuations in the final inspection. Fifth, boundary and implementability. Under strict equipment constraints (temperature, belt speed, vacuum upper and lower limits and minimum step), control laws containing indeterminate weights or requiring complex model support will increase the implementation difficulty and verification cost.

[0004] To this end, this case aims to propose a low-temperature belt drying control system and control method for traditional Chinese medicine. A sampling network is formed along the conveyor belt to continuously obtain the speed and trend information of the material moisture content change. Based on this, the feedforward of heating temperature, feedback of belt speed, and coordinated adjustment of vacuum extraction are incorporated into the same control cycle for unified decision-making. When the average moisture content and spatial fluctuation enter the stable range at the same time, the control quantity is frozen. Finally, an independent detection point is set at the tail end before discharging to make a "full-point compliance" judgment, and the parameters and results of the entire process are archived. Summary of the Invention

[0005] The present invention provides a control system and a control method for low-temperature belt drying of traditional Chinese medicine, which facilitate solving the problems mentioned in the above background technology.

[0006] The present invention provides the following technical solution: a low-temperature belt drying control method for traditional Chinese medicine, comprising: S1. Set up multiple moisture sampling points along the conveying direction of the conveyor belt of the belt drying device, uniquely number each sampling point, configure a moisture detection unit and set a fixed sampling period, record initial moisture content data, and establish the allowable setting range and minimum adjustment resolution for temperature, conveyor belt speed, and vacuum volume flow rate; S2. Based on the continuous sampling sequence, calculate the first-order and second-order time series differences of water content over time, obtain the local trend of each sampling point and the average trend of the entire field, and set the effective range and boundary conditions for trend calculation; S3. Determine the drying target moisture content and allowable fluctuation index, and obtain the current average moisture content and spatial dispersion of the entire field according to the sampling period; S4. Under the preset temperature reference and step size conditions, obtain the temperature feedforward increment according to the trend estimation result, update the heating plate temperature setting value, and apply upper and lower bound projections to the updated result; S5. Calculate the feedback adjustment amount of the conveyor belt speed based on the deviation between the current moisture content and the target and the available speed dynamic range, update the belt speed set value, and perform upper and lower bound projection; S6. Referring to the evaporation rate representation within the moving time window, obtain the coordinated adjustment amount of the vacuum pumping volume flow rate, update the vacuum set value and perform upper and lower bound projection; S7. When the average moisture content is close to the target and the spatial fluctuation is within the threshold and remains stable for a continuous period of time, the control state is determined to be stable, and the set values ​​of the heating plate temperature, conveyor belt speed, and exhaust volume flow rate are frozen; S8. Set up detection points at the end of the conveyor belt to detect the moisture content at each point. When all the preset completion conditions are met, the drying is considered complete and the cutting is triggered. At the same time, the entire record of the drying cycle, moisture content distribution and various control parameters is archived.

[0007] Optionally, the moisture sampling points are set along the conveying direction of the conveying belt of the belt drying device, each sampling point is uniquely numbered, a moisture detection unit is configured and a fixed sampling period is set, initial moisture content data is recorded, and an allowed setting range and minimum adjustment resolution of temperature, conveying belt speed, and vacuum pump volumetric flow rate are established, specifically including: obtaining the length and width of the belt conveying system of the drying machine, respectively denoted as and ; using a distributing device to uniformly distribute the wet material on the conveying belt; setting the moisture sampling points at equal intervals along the length direction of the conveying belt , numbered as ; wherein, is the interval of adjacent moisture sampling points along the length direction of the belt; is the serial number of the moisture sampling point; is the total number of moisture sampling points, ; installing an infrared moisture detection unit at each number , setting the sampling period as , and recording the moisture content as ; wherein, is the moisture sensing sampling period; is the moisture content at time at the first sampling point; is the discrete sampling time index; is the discrete sampling time index; is the discrete time index; each sampling is bounded: ; calculating the discrete time index ; wherein, is the system start time; recording all initial moisture data at the initial time ; obtaining the minimum resolution of the sensor, denoted as ; obtaining the minimum resolution of the temperature control, denoted as ; obtaining the minimum resolution of the vacuum pump volumetric flow rate, denoted as ; setting the lower and upper limits of the heating plate temperature as and , respectively; setting the lower and upper limits of the conveying belt speed as and , respectively; setting the lower and upper limits of the vacuum pump volumetric flow rate as and .

[0008] Optionally, the first and second time series differences of the water content with time are calculated based on the continuous sampling sequence to obtain local trends of each sampling point and average trends of the whole field, and effective intervals and boundary conditions of the trend calculation are set, specifically including: The first time difference function of the water content is constructed: ; wherein, is the first time difference of the water content at the point at time ; When , set ; The backward second time difference function is constructed; wherein, is the second time difference of the water content at the point at time ; When , set ; The second difference average value of the whole field at time is calculated ; The lower bound of the second difference calculation is set to .

[0009] Optionally, the drying target water content and the allowable fluctuation index are determined, and the current average water content of the whole field and the spatial dispersion are obtained according to the sampling period, specifically including: The target water content of traditional Chinese medicine drying is obtained, denoted as ; The allowable standard deviation of the water content is set to ; The average water content of the whole field at time is calculated ; The spatial standard deviation at time is calculated .

[0010] Optionally, the temperature feedforward increment is obtained according to the trend estimation result under the preset temperature reference and step size condition, the heating plate temperature set value is updated, and the upper and lower boundary projections are applied to the updated result, specifically including: setting the temperature control reference temperature ; The temperature adjustment step size is set to ; The reference evaporation acceleration reference is denoted as : ; Bind the initial temperature as ; Construct the feedforward temperature adjustment function: ; wherein, is the temperature feedforward increment at time ; Update the hot plate temperature in real time: ; wherein, is the hot plate temperature setting at time ; Implement the limit projection .

[0011] Optionally, the feedback adjustment amount of the conveying belt speed is calculated according to the deviation of the current moisture content from the target and the available speed dynamic range, the belt speed setting value is updated, and the upper and lower limit projections are performed, specifically including: Set the initial reference speed of the conveying belt ; Obtain the moisture error scale ; Obtain the available dynamic range of the belt speed ; Get the feedback adjustment coefficient of the belt speed ; Set the moisture content deviation at time ; ; Bind the initial belt speed as ; wherein, is the belt speed setting at time ; Construct the feedback speed regulation function: ; Implement the limit projection: .

[0012] Optionally, the collaborative adjustment amount of the vacuum air extraction volume flow is obtained by referring to the evaporation rate representation within the moving time window, the vacuum setting value is updated, and the upper and lower limit projections are performed, specifically including: For , calculate the first-order derivative average of the moisture: ; wherein, is the first-order difference full-field average at time ; When , let ; Set the initial vacuum volume flow reference ; Set the vacuum volume flow adjustment step ; Set the reference window length ; Computing reference evaporation rate benchmark ; wherein, is a temporary time index for computing ; and binding initial values; constructing a suction adjustment function: ; wherein, is a vacuum volume flow rate increment at time ; suction volume flow rate is updated as: ; wherein, is a vacuum volume flow rate setting at time ; implementing limit projection: .

[0013] Optionally, when the average moisture content approaches the target and the spatial fluctuation is within the threshold and remains stable within a continuous period, it is determined that the control state is stable, and the setting values of the heating plate temperature, the conveying belt speed, and the suction volume flow rate are frozen, specifically including: setting an allowable threshold of moisture content error ; If and , it is determined that the control is stable, and the control parameters are frozen: , , ; If or , the control parameters are not frozen, and the calculation and update of steps S2 to S6 are continued.

[0014] Optionally, a detection point is set at the tail of the conveying belt, the moisture content at each point is detected, and when all of them meet the preset completion condition, it is determined that the drying is completed and the cutting is triggered, and the drying cycle, moisture content distribution, and whole-process record of each control parameter are archived, specifically including: a detection point is set at the tail of the conveying belt , numbered ; wherein, is the total number of tail detection points, and ; is the tail detection point serial number; When all tail points meet , it is determined that the drying is completed, and the cutting mechanism is started; wherein, is the moisture content of the tail point at time ; the minimum time index at which all tail points meet the standard for the first time is obtained : ; Get the actual time when the judgment is completed ; Record and archive the following data: Total drying cycle time ; Final moisture content distribution ;Control parameter whole process sequence ;in, is the discrete completion index, ; If there is any Dissatisfied , then continue to perform the calculation and update of steps S2 to S6 until all satisfy Filing in cuttings.

[0015] A system for implementing the traditional Chinese medicine low-temperature belt drying control method, comprising: The conveyor belt assembly is used to carry the Chinese medicine material and move along the belt conveyor system; Multiple infrared moisture detection units are distributed on the surface of the conveyor belt to collect the moisture content of each sampling point in real time; The heating plate assembly is installed under the conveyor belt to provide a controllable heat source to the material; A vacuum extraction module is communicated with the drying chamber and is used to provide an adjustable extraction volume flow rate; The operation drive module is used to control the running speed of the conveyor belt.

[0016] The present invention has the following beneficial effects: By placing multiple moisture sampling points at equal intervals along the entire length of the conveyor belt and assigning each sampling point a unique number, comprehensive coverage and high-resolution monitoring of the entire material spreading area is achieved. Automatic data collection and normalization improve data reliability and representativeness. Unlike existing technologies that often rely on single-point or manual sampling, this solution implements simultaneous multi-point online detection and intelligent numbering management, improving spatial distribution information and data quality. This not only improves the monitoring accuracy of the material drying process, allowing for the timely detection and correction of localized dryness or wetness, but also provides a solid data foundation for subsequent trend analysis and dynamic adjustment, effectively resolving issues such as control lag and large intra-batch fluctuations caused by sparse measurement points in traditional processes.

[0017] The application introduces first-order and second-order time difference analysis in the drying process data processing, dynamically captures the rate of moisture change and its acceleration trend. Unlike the traditional end-point detection or average moisture criterion, this method can timely discover the change inflection point of dehydration rate through real-time calculation of local trend and global average trend, providing early warning and quantitative basis for subsequent temperature, speed and other regulation. By setting the effective interval and boundary conditions of trend calculation, the interference of abnormal values is effectively suppressed. This technical means not only enhances the forward-looking and anti-interference ability of the control algorithm, but also improves the fine level of regulation, breaking through the existing process quality instability problem caused by regulation lag and lack of dynamic trend analysis.

[0018] The target moisture content and spatial standard deviation are used as double criteria for the drying process, emphasizing both the compliance rate of the end point and the strict control of spatial uniformity. The system automatically calculates the average moisture content and standard deviation of the whole field, and uses them as inputs of the feedback loop to achieve precise control and batch consistency guarantee. Compared with the traditional method of determining the drying end point only by average value or experience, this scheme effectively prevents local drying unevenness or local under-drying by setting a fluctuation threshold. This provides data support for the production of high-value, composition-sensitive traditional Chinese medicinal materials, effectively improves product consistency and safety, and helps the industry move towards standardized and traceable production mode.

[0019] Unlike traditional passive feedback or manual temperature adjustment, the application proposes a temperature feedforward regulation mechanism based on moisture change trend. The system predicts future moisture content change based on real-time second-order difference results, actively adjusts the heating temperature, and prevents temperature over-limiting through upper and lower boundary projection. This mechanism reduces the impact of feedback lag, making temperature regulation more intelligent and efficient. Compared with existing technologies that mainly rely on fixed programs or single-point error feedback, feedforward regulation can suppress mutations and fluctuations in the drying process in advance, ensuring that the composition of medicinal materials is not damaged by high temperature, and avoiding energy waste. It is a key innovation to improve drying flexibility and efficiency.

[0020] The application dynamically calculates and adjusts the conveying belt speed based on the deviation between the target moisture content and the real-time measured moisture content, achieving fine control of the residence time of materials in the heating zone. Compared with the traditional fixed belt speed or manual periodic adjustment method, automatic feedback regulation can flexibly adapt to actual fluctuations in raw material moisture, material thickness and other factors, improving the adaptability of the drying process and the stability of the production line. This mechanism helps to prevent over-drying or local under-drying caused by improper belt speed, while also improving the utilization rate of production capacity, providing support for continuous industrial production.

[0021] The scheme proposes to take the vacuum pumping volume flow rate as an independent and dynamically controllable third control variable, to adjust the pumping intensity in accordance with the evaporation rate and moisture content change, and to construct a ternary control system coupling heat and mass transfer. Unlike the traditional method of simply relying on heating or belt speed adjustment, the coordinated adjustment of vacuum can better control the humidity and pressure in the cavity, improve the drying uniformity and process response speed. This method reduces the moisture regain and condensation phenomenon caused by insufficient pumping, or the surface cracking and dust escape of medicinal materials caused by excessive pumping, effectively prolongs the service life of the equipment, and ensures the integrity and safety of the quality of medicinal materials.

[0022] The application innovatively proposes a "double threshold" criterion (both the average moisture content and the spatial standard deviation meet the standard) as the basis for control stability, and introduces a control parameter freezing mechanism. Once the system reaches the set stable interval, the heating temperature, belt speed and vacuum setting are actively frozen to prevent mechanical wear and control fluctuations caused by frequent adjustments. This strategy reduces unnecessary changes in equipment operation, improves production rhythm and product consistency, and is an effective measure to ensure process stability and equipment life. Compared with the previous continuous adjustment and frequent fluctuation process, it reflects a higher level of automation and intelligent management capability.

[0023] The scheme sets up multiple detection points at the tail of the conveying belt, takes "all points in the tail meet the standard" as the drying end point criterion, and archives all key parameters during the entire drying cycle. This not only ensures the moisture consistency of the finished product batch, but also provides detailed data for post-quality traceability and process optimization. Compared with the traditional "look at the surface" or mainly sampling determination method, this method realizes the data management of the whole process, is the core link of promoting the intelligentization and standardization of traditional Chinese medicine drying production, and effectively improves the product quality assurance and production management level. BRIEF DESCRIPTION OF DRAWINGS Figure 1 The flowchart of the application is shown. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0025] Embodiment, refer to Figure 1 A low-temperature belt drying control method for traditional Chinese medicine, comprising: S1. Set up multiple moisture sampling points along the conveying direction of the conveyor belt of the belt drying device, uniquely number each sampling point, configure a moisture detection unit and set a fixed sampling period, record initial moisture content data, and establish the allowable setting range and minimum adjustment resolution for temperature, conveyor belt speed, and vacuum volume flow rate; S2. Based on the continuous sampling sequence, calculate the first-order and second-order time series differences of water content over time, obtain the local trend of each sampling point and the average trend of the entire field, and set the effective range and boundary conditions for trend calculation; S3. Determine the drying target moisture content and allowable fluctuation index, and obtain the current average moisture content and spatial dispersion of the entire field according to the sampling period; S4. Under the preset temperature reference and step size conditions, obtain the temperature feedforward increment according to the trend estimation result, update the heating plate temperature setting value, and apply upper and lower bound projections to the updated result; S5. Calculate the feedback adjustment amount of the conveyor belt speed based on the deviation between the current moisture content and the target and the available speed dynamic range, update the belt speed set value, and perform upper and lower bound projection; S6. Referring to the evaporation rate representation within the moving time window, obtain the coordinated adjustment amount of the vacuum pumping volume flow rate, update the vacuum set value and perform upper and lower bound projection; S7. When the average moisture content is close to the target and the spatial fluctuation is within the threshold and remains stable for a continuous period of time, the control state is determined to be stable, and the set values ​​of the heating plate temperature, conveyor belt speed, and exhaust volume flow rate are frozen; S8. Set up detection points at the end of the conveyor belt to detect the moisture content at each point. When all the preset completion conditions are met, the drying is considered complete and the cutting is triggered. At the same time, the entire record of the drying cycle, moisture content distribution and various control parameters is archived.

[0026] A low-temperature belt drying control method for traditional Chinese medicine (TCM) has been proposed. It integrates eight key steps: multi-point moisture sampling, time-series trend analysis, target and fluctuation control, temperature feedforward, belt speed feedback, vacuum coordination, stability criterion freezing, and tail detection and full-process archiving. This integrated sensing, analysis, and multivariable coordinated control into a closed-loop process overcomes the drawbacks of previous practices that relied on manual experience to set a single temperature or time, resulting in delayed adjustment responses, large batch fluctuations, and untraceable quality. By numbering, collecting, and recording real-time moisture data at multiple points along the belt conveyor, the spatial distribution of moisture is clearly visualized, reducing the risk of local anomalies going undetected. The introduction of a trend function enables the system to not only detect static deviations but also dynamically control the acceleration and deceleration of the drying process, thereby achieving proactive compensation. Multi-channel control—preemptive temperature adjustment, belt speed feedback correction, and vacuum rate synchronization—couples energy input, material retention, and mass transfer, improving drying efficiency and uniformity. A stable freezing strategy reduces frequent and ineffective adjustments within the target range, avoiding overshoot or fluctuations caused by system inertia. Multi-point inspection at the end of the process and data archiving provide a solid basis for finished product quality assessment and process traceability. Overall, this solution replaces the traditional manual decision-making and single-point spot checks with a fully digitized and intelligent process. This not only improves batch consistency but also reduces energy consumption, moisture regain, and over-drying risks.

[0027] The method comprises setting a plurality of moisture sampling points along the conveying direction of the conveyor belt of the belt drying device, uniquely numbering each sampling point, configuring a moisture detection unit and setting a fixed sampling period, recording initial moisture content data, and establishing an allowable setting range and minimum adjustment resolution for temperature, conveyor belt speed, and vacuum volume flow rate, specifically including: Get the length and width of the dryer belt conveyor system, which are respectively and ; Clarify the geometric dimensions of the conveyor belt to provide boundary conditions and geometric references for the subsequent determination of the number of sampling points, spacing, and material residence time, ensuring that the material distribution and sampling cover the entire heated area; Use a spreading device to evenly distribute the wet material on the conveyor belt; At equal intervals along the length of the conveyor belt Set up moisture sampling points and number them ;in, is the distance between adjacent moisture sampling points along the strip length; is the serial number of the moisture sampling point; is the total number of moisture sampling points, ; Determine the “point density” in a calculable way to ensure spatial resolution and control sensing costs; The integerization ensures that the on-site layout is feasible and strictly matches the belt length; In each number An infrared moisture detection unit is installed at each location, and the sampling period is set to , record the moisture content as ;in, is the moisture sensing sampling period; For the moment In the Moisture content at the sampling point; For the discrete sampling moments; is the discrete time index; Each sampling is bounded: ; form a time-consistent discrete data stream and use Clamping eliminates out-of-bounds and bad pixels, improving data reliability and providing a unified sampling benchmark for subsequent differential calculations; Calculating discrete-time index ;in, The system startup time; At the initial moment Record all initial moisture data ; Get the minimum resolution of the sensor, recorded as ; Get the minimum resolution of temperature control, recorded as ; Get the minimum resolution of the vacuum pump volume flow, denoted as ; Set the lower and upper limits of the heating plate temperature to and ; The upper and lower limits constitute a "safety fence" for the temperature channel. On the one hand, it provides an anchor point for the midpoint initialization of the temperature feedforward channel, so that the system is located in the middle of the controlled interval at startup, reducing excessive temperature rise or insufficient heating in the starting stage; on the other hand, it restricts the set value after each temperature update, ensuring that the feedforward increment does not exceed the medicinal material tolerance range and equipment limits, thereby avoiding risks such as effective component thermal degradation, surface hardening, or seal overheating, while also avoiding insufficient evaporation driving force and abnormally long drying time due to excessively low temperature. The fence also helps audit the control trajectory: even if there is an abnormal data point, the projection can forcibly pull the temperature back into the permitted interval. If the upper limit is too high, it is easy to touch the thermal stability threshold of sensitive medicinal materials during feedforward adjustment, causing the loss of aroma components or color deterioration; if the lower limit is too low, it will significantly weaken the evaporation in the early stage, leading to a larger moisture distribution on the belt, requiring more intense vacuum and belt speed adjustments, and increasing overall fluctuations. If the interval between the upper and lower limits is too narrow, the control action is frequent and the upper limit is reached, and the feedforward benefit is reduced, resulting in "passive edge running" of the system; if the interval is too wide, although it is flexible, it is easy to induce unnecessary large thermal shock, and the consistency of the finished product batch decreases. The thermal sensitivity of medicinal materials (such as the stable temperature range of volatile oil, steroidal saponin, and polysaccharide), the low-temperature positioning of the target process, the temperature resistance level of the conveyor belt and sealing material, the uniformity of the heating plate temperature field, and the "highest available temperature without visible quality deterioration" and "the lowest effective temperature that can maintain stable evaporation" determined by small-scale testing should be considered. Also, the long-term running upper limit of the equipment manufacturer, the temperature control resolution, and the overall effect after coupling with vacuum and belt speed should be considered. First, determine the temperature point at which quality deterioration occurs through small-scale sample testing, and set the upper limit to a safe margin below this point in industrialization; then find the lowest temperature that can maintain stable evaporation under the given vacuum and moderate belt speed, and use it as the lower limit; maintain a sufficient adjustable window between the two to allow the feedforward to function. For extremely sensitive varieties, the upper limit is recommended to be more conservative, and the lower limit is moderately raised and compensated by the vacuum channel to drive the power. For heat-resistant root materials, the window can be widened to exchange for rhythm and energy efficiency.

[0028] The lower and upper limits of the belt speed are set as and , respectively. These upper and lower limits define the minimum and maximum residence time of the material in the drying zone and serve as hard constraints for the feedback loop, mapping average moisture content deviations into "time corrections." On the one hand, they provide a midpoint as the starting speed, reducing the risk of material pile-up or underdrying at the start. On the other hand, they constrain the results of each speed update, preventing excessive belt speeds due to momentary errors, which could lead to over-drying or excessive belt speeds, resulting in material discharge before the target moisture content is reached. This directly protects the finished product from meeting standards and maintaining a stable production line cycle. If the upper limit is too high, the material residence time will be too short, resulting in frequent substandard material at the end-of-line inspection point and increased standard deviation. If the lower limit is too low, the material will remain on the hot surface for too long, increasing the probability of localized overdrying, crusting, and darkening. This can also cause accumulation upstream, impacting continuity. If the speed window is too narrow, the feedback adjustment space is insufficient, resulting in frequent system capping and a prolonged target-reaching time. If the window is too wide, large errors can lead to significant speed fluctuations, increased mechanical impact and energy consumption, and higher requirements for material distribution uniformity. The belt length, effective length of the heating zone, thickness of a single layer of material, loading per unit area, target production capacity, and the stable speed range and minimum step of the mechanical system must be considered. This should be based on the "shortest dwell time to stably meet target temperature and vacuum" and "maximum dwell time without causing quality degradation or production congestion" measured in pilot or pilot tests, while also considering the wear resistance of the strip material and the risk of the guide system running off track at low speeds. Using "full-point compliance at the end" as a hard constraint, initially fix the temperature and vacuum at midpoint and gradually increase the belt speed to find the highest speed that just meets the target. This will serve as the upper limit for the reference. The belt speed is then gradually reduced, observing for signs of adverse effects such as color, aroma, or brittleness, as well as upstream congestion, with the lowest speed that avoids abnormalities serving as the lower limit. For conditions with large fluctuations in material thickness, it is recommended to moderately narrow the speed window to reduce fluctuations. For conditions prioritizing production capacity, the upper limit can be moderately increased, but this requires simultaneous strengthening of tail-end monitoring and coordinated vacuum channel extraction capabilities.

[0029] Set the lower and upper limits of the vacuum pump volume flow rate to and ; These upper and lower limits define the effective range of vapor removal capacity and serve as the third "handle" for coupling the mass transfer side with temperature and belt speed. They provide a steady-state basis for midpoint extraction at startup and project the settings after each update, preventing insufficient extraction from causing moisture stagnation and rewetting within the chamber. They also prevent excessive extraction from entraining fines, causing surface overcooling, and placing unnecessary strain on the sealing system. Appropriate upper and lower limits also suppress pressure fluctuations and reduce drying rate fluctuations caused by vacuum fluctuations. If the upper limit is too high, the evaporative cooling effect will be too strong on the surface, leading to rapid surface drying, hindered internal diffusion, slower convergence in the rear section, and the risk of entrainment of fines, increased filter burden, and wear. If the lower limit is too low, moisture removal will not be timely, leading to increased local saturation within the chamber, rewetting, condensation, or high water content at the end, and increasing the standard deviation. If the window is too narrow, there will be insufficient room for coordinated adjustment and frequent capping. If the window is too wide, excessive extraction may increase energy consumption and mechanical fatigue, and poor coordination with temperature feedforward. It is necessary to comprehensively consider the pump type and nominal pumping speed, chamber volume and leakage level, the tolerance of the condensation and dust removal unit, the powder entrainment threshold, product sensitivity, and the steady-state vacuum level that is desired to be maintained. Reference should also be made to the terminal moisture distribution and rehumidification probability of typical batches at different pumping intensities, as well as the impact of the pumping speed on the temperature trajectory during the startup phase. The minimum step and control response time of the equipment will also affect the reasonable setting of the upper and lower limits. Under the conditions of fixed temperature and midpoint speed, gradually increase the pumping intensity, monitor the terminal moisture distribution, signs of rehumidification, and dust carryover, find the threshold of "just beginning to escape fine powder or obvious surface shrinkage", and set the upper limit within a safety margin below it; then gradually reduce the pumping, observe the points where condensation and terminal moisture appear, and use the range above it as the lower limit; at the same time, leave redundancy based on the capacity of the filtration and condensation units. For light-weight flaky or easily powdered medicinal materials, the upper limit should be more conservative and dust removal should be strengthened or baffles should be installed; for thick-layered materials or batches with high initial moisture, the lower limit can be moderately increased to avoid increased saturation in the cavity; Solidify the initial state and minimum adjustable granularity, clarify the safety boundaries, ensure that the denominators of all subsequent formulas are positive and the projections are bounded, and avoid numerical singularities and device over-limits.

[0030] By understanding the length and width of the dryer's belt conveyor system, the number and spacing of sampling points are optimally determined, ensuring data collection covers the entire heated area and avoiding quality risks caused by "blind spots" in certain areas. The material distribution device ensures even distribution of wet material across the belt surface, reducing localized accumulation or blank areas, directly improving subsequent drying uniformity. All sampling points are equipped with infrared moisture detection units and strictly numbered, with a fixed sampling cycle ensuring data consistency and traceability. Furthermore, the sampling process is bounded and bad point clamping is implemented, improving the validity and anti-interference capabilities of the collected data. Preset resolutions for sensors, temperature control, and vacuum pumps, as well as upper and lower limits for all executed quantities, establish hardware safety boundaries and the foundation for sensitivity adjustment. These details collectively address existing issues such as sparse sampling, arbitrary point distribution, and unclear parameter boundaries, which can lead to control failures and inconsistent quality batches. Through scientific data collection and parameter initialization, all subsequent adjustment steps have a unified engineering foundation and ensure quality assurance.

[0031] Based on the continuous sampling sequence, the first-order and second-order time series differences of water content over time are calculated to obtain the local trend of each sampling point and the average trend of the entire field, and the effective range and boundary conditions of the trend calculation are set, specifically including: Construct the first-order time difference function of moisture: ;in, For the Point at time The first-order time difference of moisture; when When setting ; Provides the "moisture change rate" observation value to judge the speed of the dehydration process and provide a rate benchmark for vacuum linkage and convergence criteria; Constructing the backward second-order time difference function ;in, For the Point at time Second-order time difference of moisture; when When setting ; Capturing the "curvature / acceleration" of the moisture curve allows for early identification of acceleration or deceleration trends in drying rates, providing a quantitative basis for feedforward heat increases and decreases, and reducing lag. Calculation time The second-order difference of the full-field average ; Smooth local noise and individual anomalies into a global trend, which is used as the only "global situation variable" in the feedforward channel to improve the robustness of the adjustment direction; set the positive lower bound of the second-order difference calculation to ; Provide a unified positive lower bound for all denominators involving reference acceleration to avoid numerical instability; this lower bound is directly linked to the sensor resolution and sampling period and is measurable and calculable.

[0032] The focus is on calculating moisture time-series trends based on continuous sampling sequences. This involves constructing first-order and second-order time difference functions to extract the local dehydration speed and acceleration at each sampling point, capturing the changing trend of moisture across the entire belt surface. This approach addresses the problem of traditional methods relying solely on single-point measurements or static moisture data feedback, which are unable to determine the "fast or slow change" trend in the process, leading to delayed or excessive adjustments. By calculating the trend quantity, the system can predict in advance whether the drying process has reached a "bottleneck" or "overshoot," providing a quantitative basis for the advanced and coordinated adjustment of temperature, belt speed, and vacuum. The setting of trend intervals and boundary conditions effectively filters out measurement noise and extreme anomalies, improving the robustness of the overall adjustment. Compared to drying control modes that rely on experience or single data, this step not only improves the sensitivity and foresight of control, but also provides a data basis for subsequent adaptive adjustments and fault warnings, helping to reduce the misjudgment rate and improve the stability of the drying process.

[0033] The determination of the drying target moisture content and the allowable fluctuation index, and obtaining the current average moisture content and spatial dispersion of the entire field according to the sampling period, specifically include: Get the target moisture content of Chinese medicine drying, recorded as ; Used as the central value of feedback error calculation and termination criterion to unify the finished product moisture target; Set the moisture content to allowable standard deviation ; Set hard constraints on spatial uniformity to ensure consistent quality within batches of precious tonic Chinese medicines; Calculation time Average moisture content of the entire field ; Provides the "system output" scalar of the feedback loop, directly related to Contrast generation error; Calculation time The spatial standard deviation ; Quantify the drying uniformity as a parallel threshold for freezing and release to prevent local over-drying / residual moisture.

[0034] A dual criterion of drying target moisture content and allowable fluctuation index is proposed, and the average moisture content and spatial standard deviation of the entire field are calculated in real time through the sampling period. This dual threshold mechanism solves the problem that the traditional process only focuses on the average moisture content and does not pay attention to the uniformity within the batch. The standard deviation serves as a hard constraint on spatial uniformity, so that the system not only pursues overall compliance during adjustment, but also prevents local over-drying or residual moisture. The combined effect of the dual indicators can effectively reduce the risk of intra-batch differences and local non-conformities, and improve the consistency of finished products. The real-time calculation of the entire field mean and standard deviation provides a quantitative basis for the freezing strategy and the tail compliance criterion. Compared with the traditional solution of only judging the quality of the finished product by endpoint sampling, this control method can detect local anomalies in advance and make timely adjustments, reduce the rework rate, and improve the overall production line efficiency and quality assurance capabilities.

[0035] The method of obtaining a temperature feedforward increment based on a trend estimation result under the preset temperature reference and step size conditions, updating the set value of the heating plate temperature, and applying upper and lower bound projections to the updated result specifically includes: Set the temperature control reference temperature ; Set the temperature adjustment step ; The reference evaporation acceleration is denoted as : ; The minimum temperature step that the device can distinguish and the average second-order difference that can be measured during the startup phase are used as the deterministic coefficient; When , the “sample term” on the right side of the above formula is not available yet, so Provide an effective lower bound to ensure computability. And further clarify: season ;when And according to the above formula, we can get After that, it is regarded as a constant and fixed in subsequent calculations. change; Bind the initial temperature to ; Initialize the thermal level at the midpoint of the safety range and define the reference scale with the device's minimum step and observable value to ensure a smooth start and traceable parameters. Construct a feedforward temperature regulation function: ;in, For the moment The temperature feedforward increment is linearly mapped to the temperature increase / decrease, which can realize the advance compensation of the upcoming moisture change trend and reduce the overshoot caused by feedback lag. Update the heating plate temperature in real time: ;in, For the moment The heating plate temperature setting; the feedforward correction is superimposed in a discrete integral manner to form a temperature trajectory in a continuous period to ensure a smooth transition of the execution amount; Implementing Bounds Projection ; Force the temperature setting to be within the equipment's permitted range to avoid thermal overload or insufficient heating.

[0036] The specific implementation of the temperature feedforward adjustment strategy is elaborated in detail. Taking the temperature benchmark and step size as the starting point, the temperature feedforward increment is obtained according to the trend estimation result, the heating plate temperature is updated in real time, and it is kept in the safe range through projection. This method is trend-driven rather than relying solely on deviation feedback, so that the temperature adjustment has advanced characteristics, which can prevent lag and overshoot problems in the drying process. The real-time temperature adjustment trajectory is smooth and controllable, avoiding the thermal overload, local carbonization or energy waste caused by traditional constant temperature or extensive manual adjustment. Boundary projection further ensures the safety of equipment and materials, and eliminates extreme situations of overheating or insufficient heating. Compared with the simple "heating-keeping-cooling" mode of the previous drying line, this method better adapts to changes between batches, material properties or external environment in a dynamic and feedforward manner, thereby improving energy utilization and product quality stability.

[0037] The method of calculating the feedback adjustment amount of the conveyor belt speed based on the deviation between the current moisture content and the target and the available speed dynamic range, updating the belt speed set value and performing upper and lower bound projection specifically includes: Set the initial base speed of the conveyor belt ; Get the water content error scale ; Get the available dynamic range of the belt speed ; Get the belt speed feedback adjustment coefficient ; Set the moment Moisture content deviation ; Bind the initial speed to ;in, For the moment Belt speed setting; Compare the system output with the target to generate a scalar error, and use the velocity midpoint as the initial value to avoid the extreme impact of the initial state bias on the dwell time; Construct feedback speed control function: Use the first-order relationship of "error-speed" to adjust the material residence time: if the water content is high, the speed will be reduced and delayed, and if the water content is low, the throughput will be accelerated. The control is intuitive and feasible. Implement bounds projection: ; Prevent belt speed from exceeding the limit, causing material piling / scattering or excessive delay, and ensure mechanical safety and smooth production line operation.

[0038] The feedback regulation focuses on the belt speed, realizing the real-time adaptation of material residence time and drying demand. Through the parameters such as belt speed reference, deviation scale and dynamic range, the belt speed adjustment amount is calculated in real time, so that the speed is automatically reduced when the water content is too high, and the speed is increased when the water content is too low. The limit projection prevents mechanical failure or system congestion caused by excessive adjustment. This scheme breaks through the problems of batch fluctuation and low pass rate caused by the traditional "constant belt speed" process, and realizes adaptive correction with end-point pass as a hard constraint. Its advantages are that it can dynamically respond to actual production disturbances such as raw material fluctuations, environmental changes and uneven material thickness, reduces the "local under-drying or over-drying" phenomenon, and improves the production line rhythm and batch stability. It is more flexible and intelligent than the traditional scheme, and does not require frequent manual intervention, reducing the operation and maintenance burden.

[0039] The reference evaporation rate representation in the moving time window is obtained, and the cooperative adjustment amount of the vacuum air exhaust volume flow is obtained, and the vacuum set value is updated and the upper and lower limit projection is performed, which specifically includes: For , the first-order derivative average value of moisture is calculated: ; wherein, is the first-order difference full-field average at time ; When , let ; Extract the full-field dehydration rate indicator to reflect the matching degree of evaporation and exhaust, and provide a unified input for cooperative adjustment of the vacuum side; Set the initial vacuum volume flow reference ; Set the vacuum volume flow adjustment step ; Set the reference window length ; Calculate the reference evaporation rate reference ; wherein, is a temporary time index for calculating ; And bind the initial value ; Construct the air exhaust adjustment function: ; wherein, is the vacuum volume flow increment at time ; Take the average rate as the proportional input to generate an air exhaust increment consistent with the minimum step of the device, avoiding steam retention caused by insufficient exhaust or material surface rapid cooling caused by excessive exhaust; The air exhaust volume flow is updated to: ; wherein, is the time The vacuum volume flow rate setting is discretely accumulated to form a third execution channel in parallel with the feedforward-feedback, so that the heat and mass transfer coupling can be coordinated; Implement bounds projection: ; Ensure that the vacuum pump operating point is in the safe efficiency zone to prevent excessive vacuuming or insufficient suction.

[0040] For the coordinated regulation of vacuum extraction volume flow, the vacuum set value is dynamically updated by comprehensively considering parameters such as the first-order difference mean of moisture in the entire field, the evaporation rate window, and the step size. Through coordinated heat and mass transfer, the problem that simple temperature or speed regulation cannot match the evaporation characteristics of materials at different stages is solved. This coordinated mechanism can not only suppress the surface drying, fine powder escape, and energy waste caused by water vapor retention or excessive extraction in local cavities, but also ensure drying uniformity and energy saving. Compared with traditional "constant extraction" or manual adjustment, this coordinated mechanism improves the steady-state and adaptive capabilities of the system, and helps maintain optimal extraction efficiency and product consistency under complex working conditions.

[0041] When the average moisture content is close to the target and the spatial fluctuation is within the threshold and remains stable for a continuous period of time, the control state is determined to be stable, and the set values ​​of the heating plate temperature, the conveyor belt speed, and the exhaust volume flow rate are frozen, specifically including: Set the water tolerance threshold ; If satisfied and , the control is determined to be stable and the control parameters are frozen: , , ; Using sensor resolution as the achievable accuracy, a "double threshold" judgment criterion is established to ensure that both the average target and uniformity are achieved, avoiding the situation where only the average value is used to mask local deviations. The execution volume is locked within the target range to suppress mechanical wear and quality fluctuations caused by back-and-forth adjustments, maintaining stable discharge. like or , the control parameters are not frozen, and the calculation and update of steps S2 to S6 are continued.

[0042] It is clearly stipulated that the conditions for controlling freezing are that the average moisture content is close to the target and the spatial fluctuation is within the threshold. Only when these "double thresholds" are met at the same time will the temperature, belt speed and vacuum set values ​​be frozen. This strategy solves the problems of repeated adjustments, equipment wear and batch quality fluctuations caused by traditional compliance judgment based on only a single parameter or without time stability constraints. The freezing criterion can also effectively suppress over-adjustment caused by system inertia, reducing energy consumption and mechanical loss. Under conditions where existing drying lines are prone to "over-adjustment" or "repeated fluctuations in critical points", this stable freezing strategy improves the reliability and production efficiency of the system, while providing a stable quality foundation for subsequent cutting and release.

[0043] The detection points are set at the tail of the conveyor belt to detect the moisture content at each point. When all the preset completion conditions are met, the drying is determined to be complete and the cutting is triggered. At the same time, the full record of the drying cycle, moisture content distribution and various control parameters is archived, specifically including: At the tail of the conveyor belt Test points, numbered ;in, is the total number of tail detection points, and ; The number of the tail inspection point; the judgment position is anchored at the "last section" before cutting, and the actual moisture before offline is used as the finished product judgment criterion to avoid the middle section being qualified but the tail section being not dry before the material is discharged; When all tail points satisfy , it is determined that the drying is completed and the cutting mechanism is started; wherein, For the tail Point at the moment of moisture; Get the minimum time index that first meets the tail full point requirement : ; Get the actual time when the judgment is completed ; The earliest moment when all tail points meet the standards is taken as the drying completion time, and a strict and executable cutting time is given to avoid under-drying or over-drying. Record and archive the following data: Total drying cycle time ; Final moisture content distribution ;Control parameter whole process sequence ;in, is the discrete completion index, Traceable data for the entire curing process: total duration, finished product moisture distribution and control trajectory, which can be used for batch comparison, deviation analysis and verification of final moisture standard deviation ; If there is any Dissatisfied , then continue to perform the calculation and update of steps S2 to S6 until all satisfy Archiving during cutting; ensuring that convergence can continue in the event of actual disturbance or local anomaly, until all points at the tail meet the finished product standards, and then executing cutting to ensure the consistency of the finished product.

[0044] The proposal is to implement multi-point inspection at the tail of the conveyor belt. Material cutting and release will only be carried out after all inspection points meet the standards, and the full cycle parameters will be archived. Meeting the standards at all points at the tail ensures the consistency of the final product and avoids the potential batch instability risk of "qualified in the middle but not dry at the tail." Archiving parameters throughout the entire process provides a data foundation for batch comparison, quality traceability, anomaly analysis, and continuous improvement. Compared to traditional processes that rely solely on single-point spot checks at the endpoint or manual decision-making, this mechanism enhances the scientific nature and traceability of quality assurance, and can better adapt to compliance and modern digital management requirements.

[0045] This embodiment also provides a system for controlling a low-temperature belt drying method for traditional Chinese medicine, comprising: The conveyor belt assembly is used to carry the Chinese medicine material and move along the belt conveyor system; Multiple infrared moisture detection units are distributed on the surface of the conveyor belt to collect the moisture content of each sampling point in real time; The heating plate assembly is installed under the conveyor belt to provide a controllable heat source to the material; A vacuum extraction module is communicated with the drying chamber and is used to provide an adjustable extraction volume flow rate; The operation drive module is used to control the running speed of the conveyor belt.

[0046] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for controlling low-temperature belt drying of traditional Chinese medicine, characterized in that: include: S1. Set up multiple moisture sampling points along the conveying direction of the conveyor belt of the belt drying device, uniquely number each sampling point, configure a moisture detection unit and set a fixed sampling period, record initial moisture content data, and establish the allowable setting range and minimum adjustment resolution for temperature, conveyor belt speed, and vacuum volume flow rate; S2. Based on the continuous sampling sequence, calculate the first-order and second-order time series differences of water content over time, obtain the local trend of each sampling point and the average trend of the entire field, and set the effective range and boundary conditions for trend calculation; S3. Determine the drying target moisture content and allowable fluctuation index, and obtain the current average moisture content and spatial dispersion of the entire field according to the sampling period; S4. Under the preset temperature reference and step size conditions, obtain the temperature feedforward increment according to the trend estimation result, update the heating plate temperature setting value, and apply upper and lower bound projections to the updated result; S5. Calculate the feedback adjustment amount of the conveyor belt speed based on the deviation between the current moisture content and the target and the available speed dynamic range, update the belt speed set value, and perform upper and lower bound projection; S6. Referring to the evaporation rate representation within the moving time window, obtain the coordinated adjustment amount of the vacuum pumping volume flow rate, update the vacuum set value and perform upper and lower bound projection; S7. When the average moisture content is close to the target and the spatial fluctuation is within the threshold and remains stable for a continuous period of time, the control state is determined to be stable, and the set values ​​of the heating plate temperature, conveyor belt speed, and exhaust volume flow rate are frozen; S8. Set up detection points at the end of the conveyor belt to detect the moisture content at each point. When all the preset completion conditions are met, the drying is considered complete and the cutting is triggered. At the same time, the entire record of the drying cycle, moisture content distribution and various control parameters is archived.

2. A method for controlling low-temperature belt drying of traditional Chinese medicine according to claim 1, characterized in that: The method comprises setting a plurality of moisture sampling points along the conveying direction of the conveyor belt of the belt drying device, uniquely numbering each sampling point, configuring a moisture detection unit and setting a fixed sampling period, recording initial moisture content data, and establishing an allowable setting range and minimum adjustment resolution for temperature, conveyor belt speed, and vacuum volume flow rate, specifically including: Get the length and width of the dryer belt conveyor system, which are respectively and ; Use a spreading device to evenly distribute the wet material on the conveyor belt; At equal intervals along the length of the conveyor belt Set up moisture sampling points and number them ;in, is the distance between adjacent moisture sampling points along the strip length; is the serial number of the moisture sampling point; is the total number of moisture sampling points, ; In each number An infrared moisture detection unit is installed at each location, and the sampling period is set to , record the moisture content as ;in, is the moisture sensing sampling period; For the moment In the Moisture content at the sampling point; For the discrete sampling moments; is the discrete time index; Each sampling is bounded: ; Calculating discrete-time index ;in, The system startup time; At the initial moment Record all initial moisture data ; Get the minimum resolution of the sensor, recorded as ; Get the minimum resolution of temperature control, recorded as ; Get the minimum resolution of the vacuum pump volume flow, denoted as ; Set the lower and upper limits of the heating plate temperature to and ; Set the lower and upper limits of the conveyor belt speed respectively and ; Set the lower and upper limits of the vacuum pump volume flow rate to and .

3. A method for controlling low-temperature belt drying of traditional Chinese medicine according to claim 2, characterized in that: Based on the continuous sampling sequence, the first-order and second-order time series differences of water content over time are calculated to obtain the local trend of each sampling point and the average trend of the entire field, and the effective range and boundary conditions of the trend calculation are set, specifically including: Construct the first-order time difference function of moisture: ;in, For the Point at time The first-order time difference of moisture; when When setting ; Constructing the backward second-order time difference function ;in, For the Point at time The second-order time difference of moisture; when When setting ; Calculation time The second-order difference of the full-field average ; Set the positive lower bound of the second-order difference calculation to .

4. A method for controlling low-temperature belt drying of traditional Chinese medicine according to claim 3, characterized in that: The determination of the drying target moisture content and the allowable fluctuation index, and obtaining the current average moisture content and spatial dispersion of the entire field according to the sampling period, specifically include: Get the target moisture content of Chinese medicine drying, recorded as ; Set the moisture content to allowable standard deviation ; Calculation time Average moisture content of the entire field ; Calculation time The spatial standard deviation .

5. A method for controlling low-temperature belt drying of traditional Chinese medicine according to claim 4, characterized in that: The method of obtaining a temperature feedforward increment based on a trend estimation result under the preset temperature reference and step size conditions, updating the set value of the heating plate temperature, and applying upper and lower bound projections to the updated result specifically includes: Set the temperature control reference temperature ; Set the temperature adjustment step ; The reference evaporation acceleration is denoted as : ； Bind the initial temperature to ; Construct a feedforward temperature regulation function: ;in, For the moment The temperature feed-forward increment; Update the heating plate temperature in real time: ;in, For the moment Heating plate temperature setting; Implementing Bounds Projection .

6. A method for controlling low-temperature belt drying of traditional Chinese medicine according to claim 5, characterized in that: The method of calculating the feedback adjustment amount of the conveyor belt speed based on the deviation between the current moisture content and the target and the available speed dynamic range, updating the belt speed set value and performing upper and lower bound projection specifically includes: Set the initial base speed of the conveyor belt ; Get the water content error scale ; Get the available dynamic range of the belt speed ; Get the belt speed feedback adjustment coefficient ; Set the moment Moisture content deviation ; Bind the initial speed to ;in, For the moment Belt speed setting; Construct feedback speed control function: ; Implement bounds projection: .

7. A method for controlling low-temperature belt drying of traditional Chinese medicine according to claim 6, characterized in that: The reference evaporation rate characterization within the moving time window, obtaining the coordinated adjustment amount of the vacuum pumping volume flow, updating the vacuum set value and performing the upper and lower bound projection specifically includes: for , calculate the average first-order derivative of moisture: ;in, For the moment The first-order difference of the full-field average; when season ; Setting the initial vacuum volume flow rate reference ; Setting the vacuum volume flow rate adjustment step ; Set the reference window length ; Calculate reference evaporation rate benchmark ;in, To calculate Temporary time index of ; And bind the initial value ; Construct the pumping adjustment function: ;in, For the moment The vacuum volume flow increment; The extraction volume flow rate is updated as: ;in, For the moment Vacuum volume flow setting; Implement bounds projection: .

8. A method for controlling low-temperature belt drying of traditional Chinese medicine according to claim 7, characterized in that: When the average moisture content is close to the target and the spatial fluctuation is within the threshold and remains stable for a continuous period of time, the control state is determined to be stable, and the set values ​​of the heating plate temperature, the conveyor belt speed, and the exhaust volume flow rate are frozen, specifically including: Set the water tolerance threshold ; If satisfied and , the control is determined to be stable and the control parameters are frozen: ， ， ； like or , the control parameters are not frozen, and the calculation and update of steps S2 to S6 are continued.

9. A method for controlling low-temperature belt drying of traditional Chinese medicine according to claim 8, characterized in that: The detection points are set at the tail of the conveyor belt to detect the moisture content at each point. When all the preset completion conditions are met, the drying is determined to be complete and the cutting is triggered. At the same time, the full record of the drying cycle, moisture content distribution and various control parameters is archived, specifically including: At the tail of the conveyor belt Test points, numbered ;in, is the total number of tail detection points, and ; is the tail detection point number; When all tail points satisfy , it is determined that the drying is completed and the cutting mechanism is started; wherein, For the tail Point at the moment of moisture; Get the minimum time index that first meets the tail full point requirement : ； Get the actual time when the judgment is completed ; Record and archive the following data: Total drying cycle time ; Final moisture content distribution ;Control parameter whole process sequence ;in, is the discrete completion index, ; If there is any Dissatisfied , then continue to perform the calculation and update of steps S2 to S6 until all satisfy Filing in cuttings.

10. A system using the low-temperature belt drying control method for traditional Chinese medicine according to claim 9, characterized in that: include: The conveyor belt assembly is used to carry the Chinese medicine material and move along the belt conveyor system; Multiple infrared moisture detection units are distributed on the surface of the conveyor belt to collect the moisture content of each sampling point in real time; The heating plate assembly is installed under the conveyor belt to provide a controllable heat source to the material; A vacuum extraction module is communicated with the drying chamber and is used to provide an adjustable extraction volume flow rate; The operation drive module is used to control the running speed of the conveyor belt.

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