A multi-parameter closed-loop automatic control system for low-temperature extraction of fruit juice

Abstract

This invention relates to the field of fruit processing control technology, and discloses a multi-parameter closed-loop automatic control system for low-temperature fruit juice extraction equipment, including a logic controller, a servo motor, a temperature detector, a micro-flow meter, and a proportional valve. This invention calculates the impedance index by extracting real-time torque and smoothed flow rate, and calculates the heat potential by combining real-time rotational speed. It uses a two-dimensional judgment matrix to compare thresholds to identify dual anomalies: material densification and thermal runaway accumulation. In a high-risk state, an asynchronous shielding action is initiated to cut off the link between the proportional valve and the real-time temperature feedback. An integral operation is performed on the historical heat potential to generate an integral value and output a compensation command. After the servo motor micro-retracts, a low-speed detection command is output, combined with permeability to determine the patency of the juice drainage channel. Before resuming the temperature closed-loop algorithm after the heat conduction hysteresis cycle ends, the initial integral bias parameter is used to cover historical values, ensuring a smooth transition of the output value.

Description

Technical Field

[0001] This invention relates to the field of fruit processing control technology, specifically to a multi-parameter closed-loop automatic control system for low-temperature extraction equipment of fruit juice. Background Technology

[0002] Existing low-temperature fruit juice extraction equipment relies on external sensors to collect single-dimensional physical quantities to control the production process. When the material inside the extraction chamber becomes dense and accumulates, causing the main shaft's operating resistance to rise and mechanical friction to generate heat and cause runaway, it is difficult to accurately grasp the true physical state inside the equipment by relying on a single external sensor, and thus cannot trigger the system's shutdown protection action in a timely manner.

[0003] Due to the physical time delay in heat transfer caused by the metal structure of the equipment, the temperature rise data collected by the external temperature detector exhibits a lag. This leads to distorted and delayed temperature feedback data received by the closed-loop control logic, causing a lag in the adjustment of the refrigerant injection volume. Consequently, the cooling pipes experience alternating oscillations between hot and cold media. During the recovery phase after shutdown and unclogging, excessively high transient mechanical power causes the internal materials to be subjected to a sudden and forceful push, resulting in renewed physical densification and accumulation. Furthermore, the lack of anti-sudden change calculations for historical values ​​in the integral accumulation register during the closed-loop control link switching process leads to abrupt changes in the output control values, preventing a smooth transition of the closed-loop control state.

[0004] Therefore, this invention proposes a multi-parameter closed-loop automatic control system for low-temperature fruit juice extraction equipment to address the shortcomings of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a multi-parameter closed-loop automatic control system for low-temperature fruit juice extraction equipment. This system solves the problems of: a single external sensor being unable to accurately identify the true physical state inside the equipment, resulting in the inability to trigger shutdown protection in a timely manner; distorted and delayed temperature feedback data causing alternating oscillations of hot and cold media in the cooling pipes; excessive transient mechanical power during the recovery phase causing secondary densification and accumulation of materials; and the failure to process historical values ​​of the integral accumulation register during control link switching, leading to sudden changes in output control values.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a multi-parameter closed-loop automatic control system for a low-temperature fruit juice extraction device, including a logic controller, a servo motor, a temperature detector, a micro-flow meter, and a proportional valve. The logic controller is communicatively connected to the servo motor, the temperature detector, the micro-flow meter, and the proportional valve. The servo motor has a torque feedback channel and a speed feedback channel. The temperature detector is installed on the outer wall of the extraction chamber, the micro-flow meter is installed inside the juice outlet pipe, and the proportional valve is installed inside the cooling jacket medium inlet pipe.

[0007] The logic controller sets a fixed scan cycle and synchronously reads the real-time torque and speed output by the servo motor, the raw flow rate output by the micro-flow meter, and the real-time temperature output by the temperature detector within the scan cycle. The logic controller sends a reference feed command to the servo motor and synchronously runs a temperature closed-loop algorithm, adjusting the opening of the proportional valve based on the difference between the real-time temperature and the target temperature.

[0008] The logic controller performs a sliding window averaging operation on the raw flow rate to generate a smoothed flow rate. It extracts the real-time torque and smoothed flow rate to calculate the impedance index, and extracts the real-time torque and real-time speed to calculate the heat potential. The logic controller presets a two-dimensional decision matrix and maps the impedance index and heat potential into the two-dimensional decision matrix.

[0009] When both the impedance index and the heat potential exceed the heat potential threshold, the logic controller determines that the low-temperature fruit juice extraction equipment has entered a high-risk state. The logic controller interrupts the reference feed command and temperature closed-loop algorithm execution link, outputs a micro-retraction command to the servo motor to control it to reverse, and synchronously initiates an asynchronous shielding action to disconnect the proportional valve from the real-time temperature correlation link. The logic controller extracts all historical heat potential values ​​within a preset integration time range recorded in the historical data buffer block, performs discrete-time integral accumulation algebraic operations to generate an integral heat potential value. The logic controller outputs a compensation command to the proportional valve according to the integral heat potential value, and the proportional valve opening remains at the position corresponding to the compensation command.

[0010] After the servo motor completes the micro-retraction command execution, the logic controller outputs a penetration detection command to the servo motor to control it to perform a low-speed forward rotation, calculating the penetration rate based on the smoothed flow rate change value. When the penetration rate value is greater than zero and exceeds the penetration threshold, the logic controller generates a logic true signal. Receiving the logic true signal terminates the penetration detection command and resumes the baseline feed command output action.

[0011] When the duration of the asynchronous shielding action is equal to the thermal inertia delay constant, the logic controller resumes the operation of the temperature closed-loop algorithm.

[0012] The impedance index, correlated with the algebraic ratio of the servo motor output driving force to the juice discharge flow rate, reflects the degree of material compaction. The thermal potential, transcending the heat conduction time delay, directly feeds forward to map the severity of instantaneous internal heating. The impedance threshold, related to the rated material compression resistance constant that the equipment's mechanical transmission mechanism can withstand, and the thermal threshold, related to the critical heat dissipation constant corresponding to the heat exchange capacity of the proportional valve and cooling jacket. The high-risk state zone in the two-dimensional judgment matrix represents a dual abnormality of simultaneous material compaction and uncontrolled internal thermal energy accumulation.

[0013] The micro-retraction command drives the servo motor rotor to move the internal pressing components away from the material extrusion contact surface, performing a reverse retraction action to break up the dense structure of the material accumulation. The asynchronous shielding action forcibly blocks distorted temperature rise feedback data within the heat conduction lag period from entering the closed-loop link, preventing the temperature closed-loop algorithm from erroneously receiving distorted temperature rise feedback data and causing subsequent excessive cooling signals, which could lead to abnormal internal cooling oscillations.

[0014] The integral value of the heat potential represents the total amount of additional mechanical frictional heat energy accumulated and absorbed within the material during the densification stage. A proportional valve at a fixed opening injects a constant flow of refrigerant into the cooling jacket medium inlet pipe to neutralize the additional mechanical frictional heat energy accumulated in the earlier stage.

[0015] The low-speed detection feed command generates a detection speed setting value that limits the transient mechanical power output of the servo motor, preventing the internal material from being physically densified and agglomerated again due to sudden strong pushing. The juice permeability characterizes the physical unblocking and recovery status of the internal material drainage channels after the servo motor performs a micro-retraction action. When the permeability value is greater than zero and simultaneously greater than the permeability threshold, it is confirmed that the internal material permeability has recovered to the acceptable limit for allowing the equipment to resume normal operation.

[0016] When the asynchronous shielding action duration is greater than or equal to the thermal inertia delay constant, the logic controller determines that the physical heat conduction hysteresis period has ended. The logic controller integrates the target control opening value, the proportional multiplication operation value, and the differential difference operation value, performs inverse algebraic operations to generate an initial integral bias parameter, writes this initial integral bias parameter into the frozen integral accumulation register within the temperature closed-loop algorithm, and overwrites the historical value. The digital adjustment output value smoothly transitions from a fixed value in the feedforward compensation state to a dynamically adjusted value based on deviation feedback, achieving seamless handover of the temperature control link.

[0017] This invention provides a multi-parameter closed-loop automatic control system for low-temperature fruit juice extraction equipment, which has the following beneficial effects: 1. This invention extracts the real-time torque of the servo motor and the smoothed flow rate of the micro-flowmeter to calculate the impedance index, and extracts the real-time torque and real-time speed to calculate the heat potential. The impedance index and heat potential are mapped into a preset two-dimensional judgment matrix for threshold comparison. By utilizing multi-parameter fusion judgment logic, it accurately identifies the dual abnormal conditions of material densification and uncontrolled accumulation of mechanical frictional heat energy inside the equipment, overcoming the deficiency of relying on a single external sensor to accurately grasp the true physical state inside the equipment, and promptly triggering system shutdown protection actions.

[0018] 2. This invention forcibly disconnects the proportional valve from the external real-time temperature feedback link by initiating an asynchronous shielding action under high-risk conditions. Simultaneously, it performs an integral accumulation calculation on the historical heat potential to generate an integral value of the heat potential, outputs a compensation command to the proportional valve to maintain a fixed opening, and injects a constant refrigerant. This prevents the temperature closed-loop algorithm from receiving distorted temperature rise data within the physical lag period of heat conduction, thus avoiding excessive cooling output. It utilizes the total accumulated heat energy obtained from feedforward calculations to neutralize internal mechanical friction heat, preventing the alternating oscillation of hot and cold media in the cooling pipeline.

[0019] 3. This invention outputs a low-speed detection command after the servo motor's micro-distance retraction ends, and combines this with the permeability to determine the unobstructed state of the material drainage channel, preventing secondary accumulation. Before resuming the temperature closed-loop algorithm after the physical heat conduction lag period ends, it generates an initial integral bias parameter by comprehensively considering the target control opening value, the proportional multiplication operation value, and the differential difference operation value. This initial integral bias parameter is written into the integral accumulation register to overwrite historical values. This eliminates abrupt changes in output values ​​during control link switching, ensuring a smooth transition of the digital quantity adjustment output value from a fixed feedforward value to a dynamically adjusted deviation feedback value. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the connection of the multi-parameter closed-loop automatic control system of the low-temperature fruit juice extraction equipment of the present invention.

[0021] Figure 2 This is a flowchart illustrating the steps of the multi-parameter closed-loop automatic control method for the low-temperature fruit juice extraction equipment of the present invention.

[0022] Figure 3 This is a flowchart of the sub-steps of step S100 of the present invention.

[0023] Figure 4 This is a flowchart of the sub-steps of step S200 of the present invention.

[0024] Figure 5 This is a flowchart of the sub-steps of step S300 of the present invention.

[0025] Figure 6 This is a flowchart of the sub-steps of step S400 of the present invention.

[0026] Figure 7 This is a flowchart of the sub-steps of step S500 of the present invention.

[0027] Figure 8 This is a comparison chart showing the anti-hysteresis temperature control effect in the low-temperature extraction process of fruit juice according to the present invention. Detailed Implementation

[0028] The technical solutions in 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] See Figure 1 This invention provides a multi-parameter closed-loop automatic control system for a low-temperature fruit juice extraction device, including a logic controller, a servo motor, a temperature detector, a micro-flow meter, and a proportional valve. The logic controller is communicatively connected to the servo motor, the temperature detector, the micro-flow meter, and the proportional valve. The servo motor has a torque feedback channel and a speed feedback channel. The temperature detector is installed on the outer wall of the extraction chamber, the micro-flow meter is installed inside the juice outlet pipe, and the proportional valve is installed inside the cooling jacket medium inlet pipe.

[0030] The logic controller sets a fixed scanning cycle and synchronously reads the underlying sensor data within the scanning cycle. The underlying sensor data is divided into the real-time torque and real-time speed output by the servo motor, the raw flow rate output by the micro-flow meter, and the real-time temperature output by the temperature detector. The logic controller sends a reference feed command to the servo motor and synchronously runs the temperature closed-loop algorithm. The logic controller adjusts the opening of the proportional valve according to the difference between the real-time temperature and the target temperature.

[0031] The logic controller performs a sliding window averaging operation on the original flow rate to generate a smoothed flow rate. The logic controller extracts the real-time torque and the smoothed flow rate to calculate the impedance index. The logic controller also extracts the real-time torque and the real-time speed to calculate the heat potential. The impedance index reflects the density of the material packing, and the heat potential reflects the rate at which the system's mechanical energy is converted into heat energy.

[0032] The logic controller presets a two-dimensional judgment matrix and maps the impedance index and the heat potential into the two-dimensional judgment matrix. When the impedance index is greater than the impedance threshold and the heat potential is greater than the heat threshold, the logic controller determines that the device has entered a high-risk state. The logic controller suspends the reference feed command and the temperature closed-loop algorithm. The logic controller outputs a micro-retraction command to the servo motor. The logic controller synchronously executes an asynchronous shielding action and cuts off the feedback link between the proportional valve and the real-time temperature. The logic controller outputs a compensation command to the proportional valve based on the integral value of the heat potential. The opening of the proportional valve is maintained at the position corresponding to the compensation command.

[0033] After the servo motor completes the micro-retraction command, the logic controller outputs a penetration detection command. The servo motor receives the penetration detection command and executes a low-speed forward rotation. The logic controller calculates the permeability based on the smooth flow rate change. When the permeability value exceeds zero and becomes positive, and exceeds the penetration threshold, the logic controller generates a logic true signal. The logic true signal triggers the logic controller to terminate the penetration detection command and resume the baseline feed command output. When the proportional valve opening duration reaches the thermal inertia delay constant value, the logic controller stops the asynchronous shielding action and resumes the normal operation state of the temperature closed-loop algorithm.

[0034] The logic controller defines the determination result that the permeability value is greater than zero and greater than the permeability threshold as the feed recovery condition, and the determination result that the asynchronous shielding action duration reaches the thermal inertia delay constant value as the temperature closed-loop recovery condition. The feed recovery condition is used to trigger the baseline feed command recovery action, and the temperature closed-loop recovery condition is used to trigger the temperature closed-loop algorithm recovery action.

[0035] See Figure 2 Based on the above-mentioned multi-parameter closed-loop automatic control system for low-temperature fruit juice extraction equipment, this invention also provides a multi-parameter closed-loop automatic control method for low-temperature fruit juice extraction equipment, comprising the following steps: S100, the logic controller synchronously reads the real-time torque, real-time speed, original flow rate and real-time temperature within the set scan cycle. The logic controller outputs the reference feed command to the servo motor. The logic controller calculates the temperature closed-loop algorithm based on the real-time temperature and controls the proportional valve to operate. S200, the logic controller performs a sliding window averaging operation on the original flow to generate a smooth flow. The logic controller uses real-time torque and smooth flow to calculate the impedance index. The logic controller uses real-time torque and real-time speed to calculate the heat potential. S300, the logic controller imports the impedance index and the heat potential into the two-dimensional judgment matrix to perform a numerical comparison. When the impedance index is greater than the impedance threshold and the heat potential is greater than the heat threshold, the logic controller determines that the low-temperature fruit juice extraction equipment has entered a high-risk state. S400, the logic controller interrupts the reference feed command and the temperature closed-loop algorithm operation link, the logic controller outputs a micro-retraction command to the servo motor to control the servo motor to perform a reverse action, the logic controller synchronously starts an asynchronous shielding action to cut off the link between the proportional valve and the real-time temperature, and the logic controller outputs a compensation command to the proportional valve according to the integral value of the heat potential. After the S500 servo motor completes the micro-retraction command execution action, the logic controller outputs a penetration detection command to the servo motor to control the servo motor to perform a low-speed forward rotation action. The logic controller calculates the penetration rate according to the smooth flow change value. When the penetration rate value is greater than 0 and exceeds the penetration threshold, the logic controller generates a logic true signal. The logic controller receives the logic true signal to terminate the penetration detection command and resume the baseline feed command output action. When the asynchronous shielding action maintenance time is equal to the thermal inertia delay constant value, the logic controller resumes the temperature closed-loop algorithm operation state. In step S500, the feed recovery condition includes a permeability value greater than 0 and greater than the permeation threshold, and the temperature closed-loop recovery condition includes an asynchronous shielding action duration reaching the thermal inertia delay constant value. When the feed recovery condition is met, the logic controller terminates the permeation detection command and resumes the baseline feed command output action; when the temperature closed-loop recovery condition is met, it stops the asynchronous shielding action and resumes the temperature closed-loop algorithm running state.

[0036] The following section provides a detailed description of the specific technical aspects of control flow.

[0037] See Figure 3 Step S100 includes the following sub-steps: S101, the logic controller sends a motion status read message to the servo motor. The servo motor's internal drive module receives and parses the motion status read message. The servo motor's internal drive module packages the current loop data and speed loop data recorded in its internal registers to generate a feedback message. The servo motor's internal drive module transmits the feedback message to the logic controller. The logic controller parses the feedback message to extract the real-time torque and real-time speed. The logic controller stores the real-time torque and real-time speed in a specified address in its internal memory.

[0038] S102, the rotation of gears inside the micro-flowmeter causes periodic changes in the magnetic field of the magnetic sensing element, thereby continuously outputting high-frequency pulse signals. A high-speed counting module is integrated within the logic controller. This module connects to the signal output terminal of the micro-flowmeter to receive the high-frequency pulse signals. The logic controller accumulates the number of high-frequency pulse signals within an absolute time period. The logic controller then calculates the original flow rate by multiplying the number of high-frequency pulse signals by the inherent volume equivalent constant of the micro-flowmeter.

[0039] For information on how high-speed counting modules capture pulse signal edges and calculate frequencies, those skilled in the art can consult the hardware manual for automated equipment.

[0040] S103, the temperature detector probe senses changes in heat on the outer wall of the extraction chamber and outputs a standard analog current signal. The logic controller integrates an analog-to-digital converter module. This module connects to the temperature detector's signal output to receive the standard analog current signal. The module performs analog-to-digital conversion and outputs a digital value. The logic controller performs a linear scaling transformation on the digital value based on preset upper and lower limits to generate the real-time temperature.

[0041] For analog-to-digital conversion operations performed by analog-to-analog conversion modules, those skilled in the art can refer to the industrial controller hardware architecture design specifications.

[0042] After the logic controller completes the execution of steps S101, S102 and S103, the internal memory of the logic controller synchronously updates the real-time torque, real-time speed, raw flow and real-time temperature values, in preparation for executing the subsequent closed-loop calculation process.

[0043] S104, the logic controller reads the preset base speed setting value from its internal storage area. This base speed setting value corresponds to the target operating speed of the servo motor spindle, which is associated with the equipment's normal production output. The logic controller writes the base speed setting value into the communication lower-level register, generating an industrial field communication message. The logic controller then sends a reference feed command carrying the industrial field communication message to the servo motor via the communication link.

[0044] S105, the servo motor communication interface receives the reference feed command. The servo motor's internal drive unit parses the industrial field communication message to extract the basic speed setting value. Based on the basic speed setting value, the servo motor's internal drive unit executes a low-level kinematic closed-loop algorithm to calculate the action and outputs the stator drive current. The stator drive current drives the servo motor rotor to rotate continuously along the positive coordinate system. The servo motor rotor drives the internal pressing components of the equipment to perform conventional positive extrusion and pushing actions through a mechanical transmission mechanism.

[0045] For those skilled in the art, the internal drive unit of a servo motor can refer to the standard AC servo system design manual for calculating the action and outputting the stator drive current by performing the underlying kinematic closed-loop algorithm.

[0046] S106, the logic controller reads the updated real-time temperature from the internal storage area. The logic controller also reads the preset target temperature from the internal storage area. The logic controller performs a subtraction operation to calculate the difference between the real-time temperature and the target temperature. The logic controller imports this difference into the temperature closed-loop algorithm function block. Within the temperature closed-loop algorithm function block, the logic controller performs proportional multiplication, integral accumulation, and differential difference calculations in parallel. Finally, the logic controller sums the results of these operations to generate a digital adjustment output value.

[0047] The S107 logic controller integrates a digital-to-analog converter (DAC). The logic controller uses this DAC to convert the digital output value into a standard current signal. This standard current signal is then transmitted to the proportional valve's signal receiver via a hard-wired connection. The proportional valve's internal positioning mechanism receives the standard current signal and drives the valve core mechanism. This valve core mechanism changes the valve's internal flow area, thereby regulating the flow rate of the refrigerant entering the cooling jacket's inlet pipe.

[0048] For information on the parallel execution of proportional multiplication, integral accumulation, and differential difference operations within the temperature closed-loop algorithm functional block, those skilled in the art can consult the Process Control Engineering Handbook.

[0049] See Figure 4 Step S200 includes the following sub-steps: In S201, the logic controller allocates a contiguous register address space in internal memory to construct a data queue. The logic controller sets a fixed storage length for the data queue and defines the total number of sampling points. Within each scan cycle, the logic controller acquires the raw traffic data synchronously updated at the underlying level. The logic controller writes the raw traffic data to the head position of the data queue. The logic controller synchronously executes a data shift instruction to discard the oldest historical traffic data stored at the tail position of the data queue. The data queue executes a first-in, first-out (FIFO) logic to maintain a constant data volume.

[0050] S202, the logic controller reads all traffic data elements stored internally in the data queue. The logic controller performs an algebraic summation operation on all read traffic data elements to generate a total traffic value. The logic controller divides the total traffic value by the total number of sampling points and performs an arithmetic average to calculate the smoothed traffic. The logic controller writes the smoothed traffic to a designated internal variable address for subsequent feedforward feature extraction steps.

[0051] The formula for smoothing flow rate is: ; In the formula, Q s Represents smoothed flow rate; N represents the total number of sampling points; Q ri This represents the i-th raw traffic stored inside the data queue; i represents the data queue storage address index number.

[0052] For information on how a logic controller allocates a continuous register address space in its internal memory and executes data shift instructions to construct first-in-first-out (FIFO) operating logic, those skilled in the art can refer to the Programmable Controller Underlying Storage and Pointer Operation Guide.

[0053] S203, the logic controller defines a fixed-length time window in its internal memory. The logic controller records the real-time torque and smoothed flow rate at the start of the time window. Simultaneously, the logic controller records the real-time torque and smoothed flow rate at the end of the time window. The logic controller performs subtraction algebra to calculate the difference between the real-time torque at the end and start of the time window, generating the torque change. The logic controller also performs subtraction algebra, subtracting the smoothed flow rate at the end of the time window from the smoothed flow rate at the start of the time window, to generate the smoothed flow rate change representing the degree of flow resistance attenuation.

[0054] In S204, the logic controller adds the smoothed flow rate change to a minimum constant to generate the denominator value. This minimum constant prevents hardware malfunctions caused by a zero denominator in algebraic division. The logic controller then divides the torque change by the denominator value to calculate the impedance index. The impedance index is correlated with the algebraic ratio between the servo motor's output drive force and the juice discharge flow rate. As the material density increases, the servo motor's real-time torque rises, and the smoothed juice discharge flow rate stagnates. The impedance index value increases monotonically in sync with the material density.

[0055] ; In the formula, Represents the impedance index; Represents the change in torque; ε represents the smoothed flow rate change; ε represents the minimum constant.

[0056] For information on how logic controllers allocate fixed-length time windows in their internal memory and perform subtraction and division algebraic operations, those skilled in the art can consult the programmable controller low-level instruction execution manual.

[0057] S205: Within a scan cycle, the logic controller synchronously reads the updated real-time torque and speed from the internal memory address. The logic controller calls the internal multiplication function block, importing the real-time torque and speed as input parameters. The logic controller performs a product algebra operation on the real-time torque and speed. The logic controller generates a thermal potential from the output value of the product algebra operation. Simultaneously, the logic controller allocates a contiguous address space in the internal memory to construct a historical data buffer block. The logic controller stores the currently generated thermal potential in a preset internal address register and uses first-in-first-out shift logic to continuously push the thermal potential into the historical data buffer block for subsequent integration and accumulation logic calls.

[0058] In S206, the servo motor rotates to overcome the frictional resistance of the materials inside the equipment, generating heat. This frictional heat is related to the servo motor's output mechanical power. The mechanical power is proportional to the product of the real-time torque and the real-time rotational speed. There is a time lag in the heat energy's conduction through the metal structure to the external temperature sensor. The thermal potential overcomes this time delay and directly feeds forward to map the severity of instantaneous internal heating.

[0059] ; In the formula, MHP represents the thermal potential; Tq c Represents real-time torque; ω c This represents the real-time rotational speed.

[0060] For those skilled in the art, the instructions for calling the internal multiplication function block of a logic controller to perform product algebra operations can be found in the Programmable Logic Controller Basic Programming Guide.

[0061] See Figure 5 Step S300 includes the following sub-steps: In S301, the logic controller allocates a two-dimensional array storage space in its internal memory to construct a two-dimensional decision matrix. The logic controller extracts the impedance index and defines it as the horizontal axis parameter of the two-dimensional decision matrix. The logic controller also extracts the thermal potential and defines it as the vertical axis parameter of the two-dimensional decision matrix. The real-time changes in the impedance index and thermal potential values ​​dynamically shift the coordinates within the two-dimensional decision matrix.

[0062] S302, the logic controller reads the impedance threshold and heating threshold recorded in the internal non-volatile memory. The impedance threshold is related to the rated material compression resistance constant that the mechanical transmission mechanism of the equipment can withstand. The heating threshold is related to the critical heat dissipation constant corresponding to the heat exchange capacity of the proportional valve and cooling jacket. The logic controller uses the impedance threshold to set vertical boundary reference values ​​within the two-dimensional decision matrix. The logic controller uses the heating threshold to set horizontal boundary reference values ​​within the two-dimensional decision matrix.

[0063] S303, the vertical and horizontal boundary reference values ​​divide the two-dimensional decision matrix into four independent state logic quadrants. The logic controller defines the state logic quadrant corresponding to a horizontal axis parameter greater than the impedance threshold and a vertical axis parameter greater than the heating threshold as a high-risk state protection zone. The high-risk state protection zone represents a dual abnormal situation in the fruit juice low-temperature extraction equipment where material densification and internal thermal runaway accumulation occur simultaneously.

[0064] For information on how logic controllers allocate a two-dimensional array storage space in their internal memory and read from their internal non-volatile memory areas, those skilled in the art can refer to the Industrial Logic Controller Programming Instruction Specification.

[0065] S304: The logic controller calls its internal comparison instruction function block to perform a numerical comparison operation. The logic controller imports the impedance index and impedance threshold into the numerical comparison operation pin. When the impedance index is greater than the impedance threshold, the first Boolean register inside the logic controller is set to true. Simultaneously, the logic controller imports the thermal potential and thermal threshold into the numerical comparison operation pin. When the thermal potential is greater than the thermal threshold, the second Boolean register inside the logic controller is set to true.

[0066] S305, the logic controller calls the internal logical AND operation function block. The logic controller reads the status values ​​of the first Boolean register and the second Boolean register. The logic controller performs logical AND algebraic calculations on the status values ​​of the first and second Boolean registers. When the status values ​​of the first and second Boolean registers are simultaneously true, the logic controller's internal third Boolean register outputs a true status signal.

[0067] S306, the true state signal output from the third Boolean register maps the trigger condition of the high-risk zone within the two-dimensional decision matrix. The true state signal from the third Boolean register triggers a transition in the system state machine. The internal system status flag of the logic controller transitions from the normal operating state to the high-risk state. The logic controller generates a high-risk status flag signal, triggering subsequent interrupt and protection action execution mechanisms.

[0068] The logic formula for determining a high-risk state is:

[0069] In the formula, Represents the value of the high-risk status flag; Represents the impedance index; Represents the impedance threshold; MHP represents the logical AND operator; MHP represents the thermal potential. th This represents the thermal threshold.

[0070] For those skilled in the art, the function of calling the internal comparison instruction block and the logical AND operation block to perform algebraic calculations by the logic controller can be found in the programming manual for automated control systems.

[0071] See Figure 6 Step S400 includes the following sub-steps: S401: The logic controller captures an internally generated high-risk status flag signal and triggers the highest-priority system interrupt routine. The logic controller forcibly resets the feed instruction execution register value of the corresponding underlying output channel in the internal memory area, while retaining the parameter record of the base speed setting value. The logic controller generates an offline enable message and transmits it to the servo motor via the communication link. The servo motor's internal drive unit parses the offline enable message and immediately outputs a reverse braking current. Under the action of the reverse braking current, the servo motor rotor performs an emergency stop braking action. The logic controller completes the underlying execution link interrupt action for the reference feed instruction.

[0072] S402, the logic controller reads the preset retraction angle constant and retraction speed constant from its internal non-volatile storage area. The retraction angle constant is associated with the target displacement value of the servo motor rotor's reverse rotation corresponding to breaking the dense structure of the material buildup. The logic controller packages and encapsulates the retraction angle constant and retraction speed constant to generate a position control communication message. The logic controller sends a micro-retraction command carrying the position control communication message to the servo motor to control the servo motor to perform a reverse action.

[0073] S403: The servo motor's internal drive unit analyzes the micro-retraction command to extract the retraction angle constant and retraction speed constant. Based on the retraction speed constant, the servo motor's internal drive unit generates a reverse rotation drive current. The servo motor rotor drives the internal pressing component to disengage from the material extrusion contact surface, performing a reverse retraction action. The servo motor's internal encoder continuously accumulates the number of reverse rotation pulses. When the angular displacement corresponding to the number of reverse rotation pulses equals the value of the retraction angle constant, the servo motor's internal drive unit cuts off the reverse rotation drive current. The servo motor rotor stops rotating, completing the micro-retraction command execution.

[0074] For information on the logic controller triggering the highest priority system interrupt procedure and the servo motor's internal drive unit outputting reverse braking current, those skilled in the art can refer to the Emergency Response Design Manual for Industrial Motion Control Systems.

[0075] S404: The logic controller triggers an internal interrupt event when generating the offline enable message synchronization. The logic controller invokes internal system instructions to interrupt the temperature closed-loop algorithm's execution chain. The logic controller stops executing the proportional multiplication, integral accumulation, and differential difference operations within the temperature closed-loop algorithm. The logic controller synchronously freezes the historical values ​​of the integral accumulation register and the differential difference register within the temperature closed-loop algorithm. The temperature closed-loop algorithm pauses refreshing the digital adjustment output value.

[0076] S405: The logic controller initiates an asynchronous shielding action to disconnect the proportional valve from the real-time temperature linkage. The logic controller allocates an asynchronous shielding action status bitmask in its internal memory. When the asynchronous shielding action is triggered, the logic controller sets the asynchronous shielding action status bitmask value to 1. The logic controller extracts the historical real-time temperature value from the control cycle preceding the shielding action trigger as a safety latch reference. The logic controller uses the asynchronous shielding action status bitmask to perform a weighted mask algebra operation on the updated real-time temperature value and the historical real-time temperature value to calculate the temperature closed-loop algorithm input parameters. The logic controller maps the temperature closed-loop algorithm input parameters to the temperature closed-loop algorithm feedback input pin.

[0077] The relevant data masking algebraic operation formula is: ; In the formula, T in T represents the input parameter of the temperature closed-loop algorithm. real Represents the real-time temperature updated at the underlying level; M shield Represents the asynchronous masking action status bitmask; T last This represents the historical real-time temperature value of the control cycle preceding the asynchronous shielding action.

[0078] In the S406 low-temperature fruit juice extraction equipment, internal mechanical friction generates heat, which is then transferred to the external temperature sensor location with a physical heat conduction time delay. Although the equipment stops generating heat during the micro-retraction phase, the real-time temperature of the outer wall continues to rise due to the delayed heat conduction. The status bitmask prevents distorted temperature rise feedback data within the heat conduction lag period from entering the closed-loop circuit through algebraic operations. The logic controller prevents the temperature closed-loop algorithm from incorrectly receiving distorted temperature rise feedback data, which could lead to excessive cooling signals and internal cooling oscillations. An internal high-speed timer in the logic controller starts a timing task to accumulate the asynchronous masking action duration.

[0079] For information on how a logic controller can call internal system instructions to stop the internal multiplication and accumulation operations of the closed-loop algorithm and freeze the historical values ​​of the registers, those skilled in the art can consult the industrial programmable controller underlying instruction manual.

[0080] S407: The logic controller allocates a historical data buffer block in its internal memory to continuously cache historical pyrogenic potential values ​​generated at the underlying level. The logic controller stops updating the historical data buffer block at the moment a high-risk status flag signal is generated. The logic controller retrieves all historical pyrogenic potential values ​​within a preset integration time range recorded in the historical data buffer block. The logic controller performs discrete-time integration and accumulation algebraic operations on all historical pyrogenic potential values ​​to generate an integral pyrogenic potential value. The integral pyrogenic potential value represents the total amount of additional mechanical frictional heat energy accumulated and absorbed internally by the low-temperature fruit juice extraction equipment during the material densification stage.

[0081] The formula for discrete-time integral accumulation algebraic operations is: ; In the formula, I MHP MHP represents the integral value of the thermal potential. k This represents the k-th historical thermal potential value within the historical data buffer block. M represents the absolute time period span constant; M represents the total number of historical data sampling points corresponding to the preset integration time length.

[0082] S408: The logic controller reads a pre-set feedforward compensation mapping table from its internal non-volatile memory. This table records discrete node data corresponding to multiple sets of integral values ​​of the heating potential and the target control opening of the proportional valve. The logic controller imports the integral value of the heating potential as an index parameter into the feedforward compensation mapping table to perform table lookup and linear interpolation algebra operations. Based on the target control opening value of the proportional valve output from the linear interpolation algebra operations, the logic controller generates a digital compensation command.

[0083] In S409, the internal digital-to-analog converter (DAC) of the logic controller converts the digital compensation command into a standard current signal of corresponding strength. The internal control mechanism of the proportional valve receives the standard current signal and drives the valve to the opening position corresponding to the compensation command. During the asynchronous shielding operation, the logic controller forcibly locks the value of the underlying data register bound to the designated output channel of the DAC. The logic controller stops writing new data to the designated output channel of the DAC. During the asynchronous shielding operation, the proportional valve does not respond to external feedback changes and maintains a fixed opening. In the fixed opening state, the proportional valve injects a constant flow of refrigerant into the cooling jacket medium inlet pipe to neutralize the additional mechanical friction heat energy accumulated previously.

[0084] For those skilled in the art, the following are guidelines for developing industrial data processing algorithms: logic controllers can perform discrete-time integral accumulation algebraic operations, as well as table lookup and linear interpolation algebraic operations.

[0085] See Figure 7Step S500 includes the following sub-steps: S501: The logic controller continuously monitors the internal status word messages periodically fed back by the servo motor via the communication link. The logic controller parses the internal status word messages to extract the position completion flag signal. When the position completion flag signal is in a valid true state, the logic controller determines that the physical execution of the servo motor's micro-retraction action has ended. The logic controller resets the internally generated high-risk status flag signal. The logic controller's internal system status flag transitions from the high-risk state to the penetration detection state.

[0086] S502: The logic controller reads the base speed setting value and the speed reduction attenuation coefficient recorded in the internal storage area. The speed reduction attenuation coefficient is a preset proportional constant greater than zero and less than one. The logic controller calls the internal multiplication instruction function block to perform a multiplicative algebraic operation on the base speed setting value and the speed reduction attenuation coefficient. The logic controller outputs the result of the multiplicative algebraic operation to generate the detection speed setting value. The detection speed setting value limits the transient mechanical power output of the servo motor to prevent the internal material from being physically densified and agglomerated again due to sudden strong pushing.

[0087] The algebraic formula for detecting rotational speed is: ; In the formula, N detect N represents the set value of the detection rotation speed; base Table base speed setting value; K attenuation This represents the deceleration coefficient.

[0088] In the S503, the logic controller writes the probe speed setpoint into a designated low-level communication register and encapsulates it to generate an industrial field communication message containing control instructions. The logic controller sends a low-speed probe feed command carrying the industrial field communication message to the servo motor. The servo motor's internal communication interface receives this command and transmits the message data to the internal drive unit. The servo motor's internal drive unit parses the low-speed probe feed command to extract the probe speed setpoint. The servo motor's internal drive unit calls its internal speed control loop to generate a positive stator drive current. The positive stator drive current drives the servo motor rotor to rotate at a constant speed in the forward direction according to the probe speed setpoint. The servo motor rotor, through a mechanical transmission mechanism, drives the internal pressing component to slowly approach and secondary push the loose material inside.

[0089] For information on the logic controller's continuous monitoring of the servo motor's internal status word messages and the servo motor's internal drive unit's invocation of the internal speed control loop to generate drive current, those skilled in the art can refer to the Industrial Motion Control Bus Communication Protocol Specification.

[0090] In the S504, the logic controller continuously calls the updated smoothed flow from a preset internal variable address within its internal operating cycle. The logic controller allocates two adjacent data registers in its internal memory to cache the real-time smoothed flow of the current control cycle and the historical smoothed flow of the previous control cycle, respectively. The logic controller performs a subtraction algebraic operation to calculate the difference between the real-time and historical smoothed flow values. The logic controller reads the control cycle time interval constant recorded by its internal hardware timer. The logic controller divides the numerical difference by the control cycle time interval constant to generate the differential flow value.

[0091] The formula for discrete difference operation is: ; In the formula, D Q Represents the differential value of the flow rate; Represents real-time smoothed traffic; Represents historical smoothed flow; This represents the control cycle time interval constant.

[0092] S505, the differential flow rate value is equivalent to the juice permeability of the material inside the low-temperature fruit juice extraction equipment. Juice permeability characterizes the physical unblocking and restoration of the internal material drainage channels after the servo motor performs a micro-retraction action. When the dense structure of the material is broken and the internal pores reopen, under the secondary slow pushing action of the low-speed detection feed command, the internal juice accelerates through the material layer and is discharged to the outside, resulting in a positive increasing trend in the differential flow rate value.

[0093] S506, the logic controller reads the permeation threshold recorded in its internal non-volatile memory. The permeation threshold is associated with the critical discharge rate constant required for the equipment to return to normal juice extraction. The logic controller calls its internal comparison instruction function block and imports the flow rate differential value and the permeation threshold into the comparison operation pin. The logic controller first performs a positive value determination operation on the flow rate differential value, which crosses zero, and then performs a comparison operation on the flow rate differential value and the permeation threshold. When the flow rate differential value is greater than zero and simultaneously greater than the permeation threshold, the logic controller's internal status determination register is set, outputting a true status signal. The true status signal confirms that the internal material permeability has recovered to the acceptable limit for the equipment to resume normal operation.

[0094] For information on how the logic controller calls its internal hardware timer to record the time interval constant and performs discrete difference operations, those skilled in the art can refer to the Fundamentals of Digital Signal Processing and Control.

[0095] The S507 logic controller's internal hardware interrupt service routine captures the true status signal output from the status determination register. This true status signal maps to the patency of the drainage channel within the low-temperature fruit juice extraction equipment. The logic controller responds to the true status signal and transitions its internal system status flag from the permeation detection state to the normal operating state. The logic controller retrieves the base speed setting value from its storage area. It writes this value to the communication lower-level register, generating an industrial field communication message. The logic controller then sends a reference feed command carrying the industrial field communication message to the servo motor via the field communication bus. The servo motor's internal drive unit parses the reference feed command and generates the corresponding stator drive current. The servo motor rotor resumes operation at the base speed setting value and performs the normal material pressing action.

[0096] In the S508, when the system state transitions to the normal operating state synchronization, the logic controller only removes intervention from the servo motor feed link. To avoid timing cross-interference between the feedforward state and the closed-loop state, the logic controller maintains the asynchronous shielding action state bit mask in the set state. The logic controller continuously blocks real-time temperature feedback from external temperature detectors from entering the control loop and keeps the temperature closed-loop algorithm running link in a suspended and disconnected state.

[0097] S509: The logic controller maintains a mandatory lockout command for the designated output channel of the internal digital-to-analog converter module. The logic controller continues to write digital compensation commands to the designated output channel. The proportional valve maintains a fixed opening and continues to inject a constant flow of refrigerant based on the integral value of the thermal potential, waiting for the physical end of the internal thermal inertia delay period.

[0098] In S510, the logic controller continuously monitors the asynchronous shielding action duration generated by the internal high-speed timer during the asynchronous shielding action. The logic controller reads the preset thermal inertia delay constant from its internal non-volatile memory. This thermal inertia delay constant is associated with the inherent physical time lag period of heat transfer within the internal metal structure of the fruit juice low-temperature extraction equipment. The logic controller calls its internal comparison function block to compare the asynchronous shielding action duration with the thermal inertia delay constant. When the asynchronous shielding action duration is greater than or equal to the thermal inertia delay constant, the logic controller determines that the physical heat conduction lag period has ended, and the real-time temperature collected by the external temperature sensor restores its true reflection of the internal thermal state. The logic controller internally generates a timing overflow flag signal as a backup trigger condition for restoring closed-loop control.

[0099] In S511, the logic controller responds to a timed overflow flag signal to trigger a seamless restart of the closed-loop algorithm. To avoid sudden changes in output control values ​​caused by directly switching from the feedforward open-loop state to the temperature closed-loop algorithm, the logic controller performs a non-disruptive switching calculation. Before fully activating the temperature closed-loop algorithm's execution link, the logic controller reads the target control opening value currently latched by the proportional valve. The logic controller extracts the newly generated proportional multiplication and differential difference values ​​based on the current real-time temperature from the temperature closed-loop algorithm. The logic controller combines the target control opening value, proportional multiplication value, and differential difference value to perform a reverse algebraic operation to generate the initial integral bias parameter. The logic controller forcibly writes the initial integral bias parameter into the frozen integral accumulator register inside the temperature closed-loop algorithm, overwriting its historical values.

[0100] The formula for reverse assignment initialization algebraic operations is: ; In the formula, I init V represents the initial integration bias parameter; hold P represents the target control opening value of the proportional valve in its current latched state. cal The numerical value of the proportional multiplication operation is based on the current real-time temperature, representing the temperature closed-loop algorithm. cal The numerical value represents the differential difference calculated based on the current real-time temperature using the temperature closed-loop algorithm; K i This represents the integral gain constant.

[0101] In S512, the logic controller resets the asynchronous masking status bit mask value allocated in the internal memory to zero and cancels the forced locking instruction for the specified output channel of the internal digital-to-analog converter module. After completing the value overwrite operation of the integral accumulation register, the logic controller fully reactivates the temperature closed-loop algorithm. The temperature closed-loop algorithm re-enters the periodic loop operation mode based on the initial integral bias parameter and the real-time temperature feedback from the external temperature detector. The digital quantity adjustment output value smoothly transitions from a fixed value in the feedforward compensation state to a dynamic adjustment value based on deviation feedback. The internal digital-to-analog converter module converts the smoothly transitioned digital quantity adjustment output value into a standard current signal. The proportional valve receives the standard current signal and adjusts the refrigerant injection flow rate according to the closed-loop operation result. The temperature control link of the fruit juice low-temperature extraction equipment completes seamless handover, preventing the physical phenomenon of alternating hot and cold medium oscillation in the internal pipeline.

[0102] For information on how the logic controller calls the internal comparison function block to perform numerical comparison and performs reverse assignment to the integral saturation register to prevent integral saturation, those skilled in the art can refer to the Industrial Process Control and Algorithm Regulator Design Manual.

[0103] Specific application examples: Taking a low-temperature apple juice extraction production line as an example, due to the difference in pectin content between batches of apple materials, material accumulation and densification can easily occur inside the extraction chamber, leading to mechanical overload and frictional thermal runaway. This embodiment demonstrates the multi-parameter closed-loop automatic control process of the system of the present invention when encountering this sudden situation: Routine operation phase and feature extraction (corresponding to S100-S200): The logic controller performs a scan according to an absolute time period. The current preset base speed setting in the internal storage area is 1500 rpm. In step S203, the logic controller defines a fixed-length time window in the internal memory. The smoothed flow rate at the start of the time window is recorded as 52 mL / s, and the smoothed flow rate at the end of the time window is recorded as 42 mL / s; the real-time torque at the start of the time window is recorded as 10 N·m, and the real-time torque at the end of the time window is recorded as 25 N·m. The real-time speed of the servo motor is maintained at 150 rad / s.

[0104] The logic controller performs subtraction algebraic operations: The torque change is 25-10=15N·m.

[0105] The smoothed flow rate change is 52−42=10mL / s.

[0106] Matrix mapping and state transitions (corresponding to S200-S300): Substitute into the impedance exponent calculation formula (introducing a preset minimum constant) ): ; Substitute the real-time torque and real-time speed into the formula for calculating the thermal potential: ; The logic controller reads the two-dimensional decision matrix. The preset impedance threshold is 1.20, and the heat threshold is 3000W. Substituting these values ​​into the high-risk state logic decision formula: ; Because the impedance index is greater than the impedance threshold and the thermal potential is greater than the thermal threshold, the state values ​​of the first and second Boolean registers inside the logic controller are simultaneously in the true state. The logic controller performs logical and algebraic calculations, and the internal third Boolean register outputs a true state signal. The true state signal triggers a transition in the system state machine, and the system flag changes from the normal operating state to the high-risk state. The logic controller generates a high-risk state flag signal.

[0107] Asynchronous shielding and feedforward compensation (corresponding to step S400): The logic controller captures the high-risk status flag signal generated internally and triggers the highest priority system interrupt program, interrupting the reference feed command and outputting a micro-retraction command to the servo motor. Synchronously, it initiates an asynchronous shielding action to disconnect the proportional valve from the real-time temperature linkage, setting the asynchronous shielding action status bitmask to 1.

[0108] At this point, due to heat conduction, the external sensor data spikes. Substituting this into the relevant data masking algebraic calculation formula (assuming the current underlying real-time temperature T is updated), real The temperature rose to 25°C, while the historical real-time temperature value T from the control cycle prior to the shielding action was triggered. last (for a safe temperature of 20℃): ; The input parameters of the temperature closed-loop algorithm are forcibly and securely locked at 20°C.

[0109] Simultaneously, the logic controller extracts all values ​​from the historical data buffer block and, based on the absolute time period span constant (set to 0.1s), performs discrete-time integral accumulation algebraic operations to generate a thermal potential integral value of 7500J. The logic controller imports this value into the feedforward compensation mapping table to perform table lookup and linear interpolation algebraic operations. Based on the output value, it generates a digital compensation command, forcing the internal digital-to-analog conversion module to output the corresponding standard current signal, keeping the proportional valve opening at the position corresponding to the compensation command (set to a fixed 60% opening), thus neutralizing the additional mechanical friction heat energy accumulated in the early stage.

[0110] Penetration detection and undisturbed recovery (corresponding step S500): After the servo motor completes the micro-retraction command execution, the logic controller reads the preset speed reduction attenuation coefficient as 0.2. Substituting this into the algebraic calculation formula for the detected speed: ; The logic controller generates a penetration detection command containing the detection speed setting value to control the servo motor to perform a low-speed forward rotation.

[0111] As the material drainage channel is physically cleared, the logic controller allocates adjacent data registers, reads the real-time smoothed flow rate of the current control cycle as 45 mL / s, the historical smoothed flow rate of the previous control cycle as 40 mL / s, and reads the control cycle time interval constant recorded by the hardware timer as 0.1 s. Substituting these values ​​into the discrete difference calculation formula: ; When the differential value of the flow rate is D Q It crosses zero, becomes positive, and exceeds the preset permeation threshold (set at 15 mL / s). 2When the condition is met, the internal status determination register of the logic controller is set to output a logic true signal. The logic controller responds to the logic true signal to terminate the penetration probe command and resume the output of the reference feed command.

[0112] When the logic controller determines that the duration of the accumulated asynchronous shielding action is equal to the thermal inertia delay constant (set to 30s), it triggers the closed-loop algorithm to seamlessly restart the logic.

[0113] Substitute the values ​​into the formula for initializing algebraic operations using reverse assignment and perform reverse algebraic operations: Assuming the target control opening value of the proportional valve is currently in latched state at 60%, the newly calculated proportional multiplication value based on the real-time temperature obtained from external restoration of the true mapping is 15%, the differential difference value is 1.2%, and the integral gain constant is 0.24: ; The logic controller forcibly writes the initial integral bias parameter value of 182.5% into the frozen integral accumulation register inside the temperature closed-loop algorithm, overwriting its historical value. Subsequently, the asynchronous masking action status bit mask value is reset to zero, and the logic controller resumes the normal operation state of the temperature closed-loop algorithm, achieving a smooth transition.

[0114] The experimental verification and effect comparison are as follows: See Figure 8 , Figure 8 The results demonstrate that the system of the present invention utilizes multi-parameter mapping to implement asynchronous shielding and feedforward compensation, which can eliminate control oscillations caused by physical thermal hysteresis and improve the safety and accuracy of closed-loop control of low-temperature extraction temperature.

[0115] To verify the robustness of the system in handling material densification and heating, the conventional PID feedback control method (control group) and the multi-parameter closed-loop automatic control method of this invention (experimental group) were run on a low-temperature apple juice extraction device with the same hardware platform. Material accumulation was induced by forcibly injecting high-viscosity pectin into the chamber (triggered at the 10-second mark of the experiment), and the real-time temperature change trajectory of the outer wall of the extraction chamber was recorded.

[0116] Control group (traditional PID control): When material densification occurs, due to the inherent physical time lag in heat transfer from the metal structure (heat conduction lag of approximately 30 seconds), the traditional PID algorithm fails to capture internal heat generation in the early stages and does not output any cooling regulation. However, when the lag heat is finally transferred to the external temperature detector (around the 40th second), the PID receives overshoot feedback, causing a surge in the integral accumulator register value, even leading to saturation. The sudden change in the system output control value causes fluctuations in the refrigerant injection flow rate, triggering an alternating oscillation of hot and cold media in the internal piping, with the temperature peak exceeding 28°C.

[0117] Experimental Group (Controlled by this invention): The logic controller entered a high-risk state at the 10th second through a dual-parameter mapping feedforward of impedance index and thermal potential. The system immediately initiated asynchronous shielding to forcibly block distorted temperature rise feedback data. Simultaneously, it implemented feedforward proportional opening compensation based on the integral value of the thermal potential, directly neutralizing the extra heat energy, and the temperature peak was stably suppressed at 22℃. When the thermal inertia delay constant was exhausted, the logic controller performed reverse assignment initialization algebraic operations, overcoming the integral saturation problem. The temperature closed-loop link completed a seamless handover, and the temperature curve smoothly returned to the target temperature without any abnormal system cooling oscillations.

Claims

1. A multi-parameter closed-loop automatic control system for low-temperature extraction of fruit juice, characterized in that, This includes a logic controller that connects servo motors, temperature detectors, micro-flow meters, and proportional valves. The logic controller is configured as follows: Read real-time torque, real-time speed, raw flow rate, and real-time temperature; output a reference feed command; and run a temperature closed-loop algorithm to control the proportional valve. A sliding window averaging operation is performed on the original flow rate to generate a smooth flow rate. The real-time torque and the smooth flow rate are extracted to calculate the impedance index. The real-time torque and the real-time rotational speed are extracted to calculate the heat potential. When the impedance index is greater than the preset impedance threshold and the heat potential is greater than the preset heat potential, the reference feed command and the temperature closed-loop algorithm are suspended, a micro-retraction command is output, an asynchronous shielding action is initiated and the asynchronous shielding action duration is accumulated, an accumulation algebra operation is performed on the heat potential to generate an integral value of the heat potential, and a compensation command is output to the proportional valve based on the integral value of the heat potential. The permeability is calculated based on the smooth flow rate change value. When the permeability exceeds the preset permeability threshold, the baseline feed command is restored. When the duration of the asynchronous shielding action reaches the preset thermal inertia delay constant value, the temperature closed-loop algorithm is restored.

2. The multi-parameter closed-loop automatic control system for low-temperature fruit juice extraction equipment according to claim 1, characterized in that, The logic controller integrates a high-speed counting module. The high-speed counting module receives the high-frequency pulse signal output by the micro-flow meter. The logic controller accumulates the number of high-frequency pulse signals and performs a multiplication operation on the number of high-frequency pulse signals and the inherent volume equivalent constant of the micro-flow meter to generate the original flow rate.

3. The multi-parameter closed-loop automatic control system for low-temperature fruit juice extraction equipment according to claim 1, characterized in that, The logic controller constructs a data queue, defines the total number of sampling points, writes the raw traffic to the head position of the data queue, and synchronously discards the earliest historical traffic data stored at the tail position of the data queue. The logic controller performs an algebraic summation operation on all traffic data elements stored in the data queue to generate a total traffic value, and performs an arithmetic average operation on the total traffic value and the total number of sampling points to generate the smoothed traffic.

4. The multi-parameter closed-loop automatic control system for low-temperature fruit juice extraction equipment according to claim 1, characterized in that, The logic controller defines a fixed-length time window, calculates the real-time torque difference between the end position and the beginning position of the time window to generate the torque change, subtracts the smoothed flow rate from the smoothed flow rate at the end position of the time window to generate the smoothed flow rate change, and combines the torque change with the smoothed flow rate change to generate the impedance index; the logic controller performs a product algebra operation on the real-time torque and the real-time speed to generate the heat potential.

5. The multi-parameter closed-loop automatic control system for low-temperature fruit juice extraction equipment according to claim 1, characterized in that, The logic controller constructs a two-dimensional decision matrix, defining the impedance index as the horizontal axis parameter of the two-dimensional decision matrix and the thermal potential as the vertical axis parameter of the two-dimensional decision matrix. The logic controller calls the internal comparison instruction function block to perform a numerical comparison action. When the horizontal axis coordinate parameter is greater than the impedance threshold and the vertical axis coordinate parameter is greater than the heating threshold, the logic controller generates a high-risk status flag signal, triggering the suspension of the reference feed instruction and the temperature closed-loop algorithm.

6. The multi-parameter closed-loop automatic control system for low-temperature fruit juice extraction equipment according to claim 5, characterized in that, The logic controller captures the high-risk status flag signal, generates an offline enable message, transmits it to the servo motor to trigger the output of reverse braking current to perform an emergency stop braking action, and then sends a position control communication message containing a retraction angle constant and a retraction speed constant as the micro retraction command to control the servo motor to perform a reverse action. The logic controller extracts all historical thermal potential values ​​within a preset integration time range, and performs discrete-time integral accumulation algebraic operations on all historical thermal potential values ​​to generate the thermal potential integral value.

7. The multi-parameter closed-loop automatic control system for low-temperature fruit juice extraction equipment according to claim 1, characterized in that, The logic controller reads and records a feedforward compensation mapping table that shows the corresponding node data between multiple sets of integral values ​​of thermal potential and the target control opening of the proportional valve. The logic controller imports the integral value of the heat potential into the feedforward compensation mapping table to perform table lookup and linear interpolation algebra operations. Based on the proportional valve target control opening value output by the linear interpolation algebra operation, it generates a digital compensation command, converts the digital compensation command into a standard current signal, and drives the proportional valve to the corresponding opening position.

8. The multi-parameter closed-loop automatic control system for low-temperature fruit juice extraction equipment according to claim 1, characterized in that, The specific steps of initiating the asynchronous masking action include: The logic controller allocates an asynchronous shielding action status bitmask, extracts the historical real-time temperature value of the control cycle before the shielding action is triggered as a safety latching reference, and performs a weighted mask algebra operation on the updated real-time temperature and the historical real-time temperature value using the asynchronous shielding action status bitmask to obtain the temperature closed-loop algorithm input parameters. The temperature closed-loop algorithm input parameters are then mapped to the feedback input pin of the temperature closed-loop algorithm to forcibly block distorted temperature rise feedback data from entering the closed-loop link.

9. The multi-parameter closed-loop automatic control system for low-temperature fruit juice extraction equipment according to claim 1, characterized in that, After the logic controller determines that the servo motor's micro-retraction action has ended, it sends a low-speed detection feed command to the servo motor to control the servo motor to rotate in the forward direction at a constant speed according to the detection speed. The logic controller performs a subtraction algebra operation to calculate the difference between the real-time smoothed flow rate of the current control cycle and the historical smoothed flow rate of the previous control cycle. The difference is then combined with the control cycle time interval constant to perform a discrete difference operation to generate a flow rate differential value, which is mapped to the penetration rate.

10. The multi-parameter closed-loop automatic control system for low-temperature fruit juice extraction equipment according to claim 1, characterized in that, When the duration of the asynchronous shielding action reaches the value of the thermal inertia delay constant, the logic controller performs a disturbance-free switching calculation action; the logic controller extracts the target control opening value of the proportional valve currently in the latched state, the proportional multiplication operation value and the differential difference operation value newly generated by the temperature closed-loop algorithm, performs reverse assignment initialization algebra operation to generate an initial integral bias parameter, forcibly writes the initial integral bias parameter into the frozen integral accumulation register, and then reactivates the temperature closed-loop algorithm.

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