Organ perfusion temperature control method and system based on cascade control

Abstract

The application relates to the technical field of organ perfusion temperature control, and discloses an organ perfusion temperature control method and system based on cascade control, which comprises the following steps: obtaining the outlet water temperature, return water temperature and pipeline flow by using an outer loop control circuit, and obtaining the water tank internal temperature and liquid level by using an inner loop control circuit; reconstructing the control parameters of the inner loop control circuit based on the liquid level; calculating an actual feedforward temperature compensation amount based on the outlet water temperature, return water temperature and pipeline flow; calculating a basic target temperature based on the outlet water temperature and a preset outlet water temperature; generating a final target temperature of the inner loop control circuit based on the actual feedforward temperature compensation amount and the basic target temperature; calculating a basic power based on the final target temperature and the inner loop reconstruction control parameters; and generating a basic power adjustment instruction based on the basic power and outputting the basic power adjustment instruction to a driving circuit to drive the power of the adjustment semiconductor refrigerating sheet. The application improves the precision and stability of organ perfusion temperature control.

Description

Technical Field

[0001] This invention relates to the field of organ perfusion temperature control technology, and more specifically, to an organ perfusion temperature control method and system based on cascade control. Background Technology

[0002] Organ perfusion is a key technology that involves injecting perfusion fluid into the vascular system of an isolated organ to maintain its viability and prolong its preservation time. Its effectiveness directly depends on the precise control of the perfusion environment. Temperature control is a core challenge—the preservation fluid must be maintained at a low temperature to reduce organ metabolism and ischemic damage, simulating an organ's "dormant" state to minimize ischemic injury and create conditions conducive to transplantation. Some mechanical perfusion methods also require dynamically adapting to restorative temperatures to support organ function maintenance; temperature control failure will directly lead to organ damage, thus becoming a crucial step in ensuring perfusion quality.

[0003] Current organ perfusion temperature control systems suffer from a double hysteresis problem in their heat transfer pathways. First, the heat capacity of the medium is affected by its volume, leading to a slow response to heating or cooling. Second, the flow of the medium in the pipeline is unstable due to real-time flow rate changes, creating an additional time delay. These two types of hysteresis overlap and change dynamically, making it difficult for traditional control strategies to address simultaneously—single-loop regulation is prone to overshoot or insufficient response, resulting in low system temperature control accuracy and poor stability, severely impacting the quality of organ perfusion. Summary of the Invention

[0004] In view of this, the present invention provides an organ perfusion temperature control method and system based on cascade control to solve the problems of low accuracy and poor stability of organ perfusion temperature control.

[0005] In a first aspect, the present invention provides an organ perfusion temperature control method based on cascade control. This method is applied to an organ perfusion device, which includes an organ chamber, a heat exchange water tank, an oxygenator, and a semiconductor refrigeration chip. The organ chamber is used to preserve organs, the heat exchange water tank is used to store water, and indirect heat exchange is performed between the water and the perfusion fluid in the organ chamber through water circulation to control the temperature of the perfusion fluid. The oxygenator is used for gas exchange, and the semiconductor refrigeration chip is used to regulate the temperature of the medium in the heat exchange water tank. The method includes: using an outer loop control loop to obtain the outlet temperature of the heat exchange water tank, the return water temperature of the heat exchange water tank, and the pipeline flow rate between the temperature-changing zones of the heat exchange water tank and the oxygenator; and using an inner loop control loop to obtain... The system calculates the internal temperature and liquid level of the heat exchange water tank; reconstructs the control parameters of the inner loop control circuit based on the liquid level to obtain the reconstructed inner loop control parameters; updates the controller parameters in the inner loop control circuit based on the reconstructed inner loop control parameters; calculates the actual feedforward temperature compensation based on the outlet temperature, return water temperature, and pipeline flow rate; calculates the basic target temperature based on the outlet temperature and the preset outlet temperature; generates the final target temperature of the inner loop control circuit based on the actual feedforward temperature compensation and the basic target temperature; calculates the basic power based on the final target temperature and the reconstructed inner loop control parameters; and generates a basic power adjustment command based on the basic power and outputs it to the drive circuit to drive and adjust the power of the semiconductor cooling chip.

[0006] In one optional implementation, the control parameters of the inner loop control circuit are reconstructed based on the liquid level to obtain the inner loop reconstructed control parameters, including: calculating the heat capacity proportional factor based on the liquid level and the rated full-load liquid level; and reconstructing the control parameters of the inner loop control circuit based on the heat capacity proportional factor and a preset dynamic mapping function to obtain the inner loop reconstructed control parameters, wherein the control parameters include proportional, integral gain and differential damping.

[0007] In one optional implementation, the preset dynamic mapping function is a nonlinear parameter adjustment function based on the heat capacity scaling factor, and its mathematical form is: , in, For the inner ring reconstruction ratio, Indicates time, To reconstruct the integral gain of the inner loop, For the inner loop, reconstruct the differential damping. This is the proportional reference parameter under full load liquid level. The integral gain reference parameter is the value at full load liquid level. These are the differential damping reference parameters at full load liquid level. This is the heat capacity scaling factor. This is a proportional adjustment function. This is the integral gain adjustment function. This is the differential damping adjustment function.

[0008] In one alternative implementation, the scaling function Integral gain adjustment function and differential damping adjustment function According to the heat capacity ratio factor The range in which it is located is determined, including: based on the heat capacity scaling factor. And the range where the heat capacity scaling factor threshold is located; if the heat capacity scaling factor If the value is greater than or equal to the high heat capacity scaling factor threshold, it is determined to be a high liquid level zone, and a benchmark mapping strategy is used to obtain the scaling adjustment function. Integral gain adjustment function and differential damping adjustment function If the heat capacity ratio factor If the liquid level is greater than the low heat capacity proportionality factor threshold but less than the high heat capacity proportionality factor threshold, it is determined to be in the middle liquid level zone, and a smooth nonlinear adjustment strategy is used to obtain the proportional adjustment function. Integral gain adjustment function and differential damping adjustment function If the heat capacity ratio factor If the value is less than or equal to the low heat capacity scaling factor threshold, it is determined to be a low liquid level zone, and a strong suppression strategy is used to obtain the scaling adjustment function. Integral gain adjustment function and differential damping adjustment function .

[0009] In one optional implementation, the actual feedforward temperature compensation is calculated based on the outlet temperature, return water temperature, and pipeline flow rate, including: calculating the transient heat load based on the outlet temperature, return water temperature, pipeline flow rate, specific heat capacity, and fluid density; calculating the ideal feedforward temperature compensation based on the transient heat load and a preset basic feedforward conversion coefficient; generating the current liquid level weight based on the liquid level and a preset weighting function; and calculating the actual feedforward temperature compensation based on the ideal feedforward temperature compensation and the current liquid level weight.

[0010] In one optional implementation, a preset weighting function takes a heat capacity ratio factor and a liquid level change rate as input parameters. The heat capacity ratio factor is calculated from the liquid level and the rated full-load liquid level, and the liquid level change rate is the rate of change of the heat capacity ratio factor over time.

[0011] The present invention provides an organ perfusion temperature control method based on cascade control, which further includes: acquiring the perfusion fluid temperature, and determining whether the perfusion fluid temperature meets the standard based on the absolute value of the difference between the perfusion fluid temperature and the final target temperature and a preset deviation range: if the absolute value of the difference between the perfusion fluid temperature and the final target temperature is less than or equal to the preset deviation range, the perfusion fluid temperature is determined to meet the standard; if the absolute value of the difference between the perfusion fluid temperature and the final target temperature is greater than the preset deviation range, the perfusion fluid temperature is determined to not meet the standard.

[0012] In one optional implementation, when it is determined that the injection fluid temperature has not met the target, it is determined whether the difference between the injection fluid temperature and the final target temperature is less than or equal to a small deviation threshold; if the difference between the injection fluid temperature and the final target temperature is less than or equal to the small deviation threshold, the differential damping in the inner loop reconfiguration control parameters is adjusted; if the difference between the injection fluid temperature and the final target temperature is greater than the small deviation threshold, it is determined whether the difference between the injection fluid temperature and the final target temperature is greater than zero; if the difference between the injection fluid temperature and the final target temperature is greater than zero, the actual feedforward temperature compensation is reduced; if the difference between the injection fluid temperature and the final target temperature is less than zero, the actual feedforward temperature compensation is increased.

[0013] In one optional implementation, the base power is calculated based on the final target temperature and the inner loop reconfiguration control parameters, including: calculating the difference between the final target temperature and the internal temperature of the water tank to obtain the temperature deviation; and calculating the power based on the inner loop reconfiguration control parameters and the temperature deviation to obtain the base power.

[0014] In a second aspect, the present invention provides an organ perfusion temperature control system based on cascade control, comprising: an organ perfusion device and a main control unit, wherein the organ perfusion device is used to control the temperature of the perfusion fluid through heat exchange, and the main control unit is used to execute the organ perfusion temperature control method based on cascade control described in the first aspect or any corresponding embodiment thereof.

[0015] The organ perfusion temperature control method based on cascade control provided in this invention first utilizes a dual-closed-loop cascade control architecture constructed in the main control unit. The outer loop control loop uses the outlet temperature as the controlled variable, sets a long sampling period to match the pipeline transmission time delay, and obtains the outlet temperature, return water temperature, and pipeline flow rate. The inner loop control loop uses the internal temperature of the water tank as the controlled variable, sets a short sampling period to respond to the transient changes of the thermoelectric cooler, and obtains the internal temperature and liquid level of the water tank. By constructing a control framework with coordinated main and auxiliary loops, asymmetric sampling is used to achieve preliminary physical isolation of internal and external thermal disturbances, laying the foundation for subsequent precise temperature control. Next, the parameters of the inner loop PID controller are dynamically reconstructed based on the real-time liquid level to obtain inner loop reconstructed control parameters adapted to the current medium storage (heat capacity), thereby mitigating the problem of heat capacity changes (capacity lag) caused by liquid level fluctuations. This allows the inner loop control loop to respond more accurately to the transient thermodynamic changes of the thermoelectric cooler and reduces response lag. The reconstructed control parameters of the inner loop are written into the inner loop PID controller, replacing the original fixed parameters. This allows the inner loop controller to match the dynamic changes in the water tank's heat capacity in real time, ensuring that the internal temperature of the water tank quickly and stably follows the target value, guaranteeing precise temperature control. Next, based on the outlet temperature, return water temperature, and pipeline flow rate, the actual feedforward temperature compensation is calculated. This feedforward mechanism proactively offsets external thermal shocks such as organ access, preventing significant deviations in the outlet temperature and protecting small heat capacity systems from damage due to excessive compensation, thus improving disturbance rejection foresight. Then, the outer loop PID controller compares the actual outlet temperature with the user-preset temperature, calculates the deviation, and outputs the basic target temperature. This initially balances the impact of pipeline transmission time lag, providing a stable basic temperature control direction for the inner loop control loop. The actual feedforward temperature compensation is then added as an bias term to the basic target temperature to generate the final target temperature of the inner loop control loop. This integrates feedforward disturbance rejection and basic temperature control requirements, allowing the inner loop target to more accurately adapt to dynamic environmental changes. Then, the inner-loop PID controller calculates the base power driving the thermoelectric cooler based on the deviation between the final target temperature and the actual temperature of the water tank, combined with the inner-loop reconstructed control parameters. This allows for rapid response to transient changes in the thermoelectric cooler, suppressing oscillation overshoot caused by liquid level fluctuations, and improving the accuracy of inner-loop temperature control. Finally, the base power is converted into an adjustment command output to the drive circuit, driving the thermoelectric cooler to output power and achieve precise temperature regulation of the heat exchange water tank, ensuring stable organ perfusion fluid temperature and supporting organ viability maintenance. This method constructs a dedicated controller structure for long-lag water circuit systems in medical perfusion. Flow feedforward addresses the spatial propagation lag of external disturbances, while a liquid level-linked PID controller addresses the physical thermal capacity lag in the execution stage. The combination of these two approaches with dual-closed-loop cascade control perfectly decouples the originally highly nonlinear and strongly coupled variable-parameter temperature control system, greatly improving the temperature stability and organ safety of medical equipment under complex operating conditions. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic flowchart of an organ perfusion temperature control method based on cascade control according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the organ perfusion temperature control system based on cascade control according to an embodiment of the present invention; Figure 3 This is a schematic diagram of another organ perfusion temperature control system based on cascade control according to an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0019] According to embodiments of the present invention, an organ perfusion temperature control system based on cascade control is provided, such as... Figure 2As shown, the system includes an organ perfusion device and a main control unit. The organ perfusion device is used to control the temperature of the perfusion fluid through heat exchange. The organ perfusion device includes: an organ compartment 1, a heat exchange water tank 2, a level sensor 3, a flow sensor 4, a first temperature sensor 5, a second temperature sensor 6, a third temperature sensor 7, a semiconductor cooling chip 8, a drive circuit 9, and an oxygenator 10. The organ compartment 1 is used to preserve organs, and the heat exchange water tank 2 is used to store water. Water circulates and indirectly exchanges heat with the perfusion fluid in the organ compartment 1 to control the perfusion fluid temperature. The level sensor 3 measures the level of the water in the heat exchange water tank 2, and the flow sensor 4 measures the flow rate in the pipeline between the heat exchange water tank 2 and the temperature-changing zone of the oxygenator 10. The system includes a first temperature sensor 5 located inside the heat exchange water tank 2 to measure the internal temperature, a second temperature sensor 6 located at the outlet pipe of the heat exchange water tank 2 to measure the outlet temperature, a third temperature sensor 7 located at the return pipe of the heat exchange water tank 2 to measure the return water temperature, a semiconductor cooling chip 8 to regulate the water temperature in the heat exchange water tank 2, a drive circuit 9 to drive and adjust the power of the semiconductor cooling chip 8 according to the basic power adjustment command output by the main control unit 11 to achieve injection fluid temperature control, and an oxygenator 10 for gas exchange.

[0020] The main control unit 11 is used to perform, for example Figure 1 The organ perfusion temperature control method based on cascade control generates basic power adjustment commands.

[0021] According to an embodiment of the present invention, an embodiment of an organ perfusion temperature control method based on cascade control is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0022] This embodiment provides an organ perfusion temperature control method based on cascade control, which can be used in the aforementioned mobile terminals, such as mobile phones and tablets. Figure 1 This is a flowchart of an organ perfusion temperature control method based on cascade control according to an embodiment of the present invention, as shown below. Figure 1 As shown, the process includes the following steps: Step S101: Use the outer loop control loop to obtain the outlet temperature of the heat exchange water tank, the return water temperature of the heat exchange water tank, and the pipeline flow rate between the heat exchange water tank and the temperature change zone of the oxygenator. Use the inner loop control loop to obtain the internal temperature of the heat exchange water tank and the liquid level of the heat exchange water tank.

[0023] In this embodiment, the main control unit establishes two cascaded control loops with asymmetric sampling periods: an outer loop control loop and an inner loop control loop. The outer loop control loop (main loop) uses the outlet temperature as the controlled variable and sets a relatively long sampling period (e.g., the sampling period of the main loop). To match the time delay of water flow in the pipeline, the outlet temperature, return water temperature, and pipeline flow rate are obtained. Inner loop control loop (secondary loop): The internal temperature of the water tank is the controlled variable, and a shorter sampling period is set (e.g., the secondary loop sampling period). It can quickly respond to transient thermodynamic changes in the semiconductor cooling chip 8 by acquiring the internal temperature and liquid level of the water tank.

[0024] Step S102: Based on the liquid level, the control parameters of the inner loop control circuit are reconstructed to obtain the reconstructed inner loop control parameters.

[0025] In this embodiment, the control parameters of the inner loop PID controller (Proportional-Integral-Derivative) are dynamically reconstructed based on the liquid level: Since fluctuations in the water tank level will change the medium storage (heat capacity), thus affecting the heating / cooling response characteristics, it is necessary to adjust the control parameters of the inner loop PID controller according to the real-time liquid level value and preset rules to obtain inner loop reconstructed control parameters that are adapted to the current heat capacity. This allows the inner loop control loop to respond more accurately to the transient thermodynamic changes of the semiconductor refrigeration chip 8, alleviating the slow response problem caused by capacity hysteresis.

[0026] Step S103: Update the controller parameters in the inner loop control loop based on the inner loop reconfiguration control parameters.

[0027] In this embodiment, the inner loop reconstruction control parameters obtained from liquid level reconstruction are directly written into the inner loop PID controller of the inner loop control loop, replacing its original fixed parameters. This enables the inner loop controller to match the dynamic changes in the water tank's heat capacity in real time, thereby quickly and stably ensuring that the internal temperature of the water tank continuously follows the target value changes, alleviating the slow response caused by capacity lag, and ensuring precise and controllable temperature.

[0028] Step S104: Calculate the actual feedforward temperature compensation based on the outlet temperature, return water temperature, and pipeline flow rate.

[0029] This embodiment calculates the actual feedforward temperature compensation based on the outlet temperature, return water temperature, and pipeline flow rate. By proactively offsetting external thermal shocks, it avoids significant deviations in the outlet temperature and prevents damage to small heat capacities due to excessive compensation, thereby improving the anti-interference foresight.

[0030] Step S105: Calculate the basic target temperature based on the outlet temperature and the preset outlet temperature.

[0031] This embodiment uses the outer loop control loop as its core, and collects the actual outlet temperature through a relatively long sampling period (matching the pipeline transmission time delay), comparing it with the user-preset target temperature. In comparison, after the outer loop PID controller calculates the deviation, it outputs a basic inner loop target temperature setpoint (i.e., the basic target temperature). This is used to initially balance the effects of pipeline delay and provide a stable basic temperature control direction for the inner loop.

[0032] Step S106: Generate the final target temperature of the inner loop control loop based on the actual feedforward temperature compensation amount and the basic target temperature.

[0033] In this embodiment, the actual feedforward temperature compensation obtained in step S104 is directly superimposed on the basic target temperature as a temperature bias term to form the final target temperature that the inner loop control loop needs to track. By integrating feedforward disturbance rejection and basic temperature control requirements, the inner loop target can more accurately adapt to dynamic environmental changes.

[0034] Step S107: Calculate the base power based on the final target temperature and the inner loop reconfiguration control parameters.

[0035] This embodiment uses an inner-loop control loop as a foundation. Based on the PID control parameters reconstructed from the final target temperature and liquid level (adapted to the current heat capacity), it calculates the basic power command to drive the thermoelectric cooler 8. This allows the inner-loop control loop to respond quickly to transient thermodynamic changes in the thermoelectric cooler 8, suppressing oscillations and overshoot caused by liquid level fluctuations, and improving temperature control accuracy.

[0036] Step S108: Generate a basic power adjustment command based on the basic power and output it to the drive circuit to drive and adjust the power of the semiconductor cooling chip.

[0037] In this embodiment, the base power calculated in step S107 is converted into a specific adjustment command and output to the drive circuit to control the power output of the semiconductor cooling chip 8. The effect is to ultimately achieve precise adjustment of the heat exchange water tank temperature, ensure stable organ perfusion fluid temperature, and support the maintenance of organ viability.

[0038] The organ perfusion temperature control method based on cascade control provided in this embodiment first utilizes a dual-closed-loop cascade control architecture built in the main control unit. The outer loop control loop uses the outlet temperature as the controlled variable, sets a long sampling period to match the pipeline transmission time delay, and obtains the outlet temperature, return water temperature, and pipeline flow rate. The inner loop control loop uses the internal temperature of the water tank as the controlled variable, sets a short sampling period to respond to the transient changes of the thermoelectric cooler, and obtains the internal temperature and liquid level of the water tank. By constructing a control framework with coordinated main and auxiliary loops, asymmetric sampling is used to achieve preliminary physical isolation of internal and external thermal disturbances, laying the foundation for subsequent precise temperature control. Next, the parameters of the inner loop PID controller are dynamically reconstructed based on the real-time liquid level to obtain inner loop reconstructed control parameters adapted to the current medium storage (heat capacity), thereby mitigating the problem of heat capacity changes (capacity lag) caused by liquid level fluctuations. This allows the inner loop control loop to respond more accurately to the transient thermodynamic changes of the thermoelectric cooler and reduces response lag. The reconstructed control parameters of the inner loop are written into the inner loop PID controller, replacing the original fixed parameters. This allows the inner loop controller to match the dynamic changes in the water tank's heat capacity in real time, ensuring that the internal temperature of the water tank quickly and stably follows the target value, guaranteeing precise temperature control. Next, based on the outlet temperature, return water temperature, and pipeline flow rate, the actual feedforward temperature compensation is calculated. This feedforward mechanism proactively offsets external thermal shocks such as organ access, preventing significant deviations in the outlet temperature and protecting small heat capacity systems from damage due to excessive compensation, thus improving disturbance rejection foresight. Then, the outer loop PID controller compares the actual outlet temperature with the user-preset temperature, calculates the deviation, and outputs the basic target temperature. This initially balances the impact of pipeline transmission time lag, providing a stable basic temperature control direction for the inner loop control loop. The actual feedforward temperature compensation is then added as an bias term to the basic target temperature to generate the final target temperature of the inner loop control loop. This integrates feedforward disturbance rejection and basic temperature control requirements, allowing the inner loop target to more accurately adapt to dynamic environmental changes. Then, the inner-loop PID controller calculates the base power driving the thermoelectric cooler based on the deviation between the final target temperature and the actual temperature of the water tank, combined with the inner-loop reconstructed control parameters. This allows for rapid response to transient changes in the thermoelectric cooler, suppressing oscillation overshoot caused by liquid level fluctuations, and improving the accuracy of inner-loop temperature control. Finally, the base power is converted into an adjustment command output to the drive circuit, driving the thermoelectric cooler to output power and achieve precise temperature regulation of the heat exchange water tank, ensuring stable organ perfusion fluid temperature and supporting organ viability maintenance. This method constructs a dedicated controller structure for long-lag water circuit systems in medical perfusion. Flow feedforward addresses the spatial propagation lag of external disturbances, while a liquid level-linked PID controller addresses the physical thermal capacity lag in the execution stage. The combination of these two approaches with dual-closed-loop cascade control perfectly decouples the originally highly nonlinear and strongly coupled variable-parameter temperature control system, greatly improving the temperature stability and organ safety of medical equipment under complex operating conditions.

[0039] In some optional implementations, the process of reconstructing the control parameters of the inner loop control circuit based on the liquid level in step S102 to obtain the reconstructed inner loop control parameters mainly includes: Step S1021: Calculate the heat capacity ratio factor based on the liquid level and the rated full-load liquid level.

[0040] In this embodiment, the liquid level is collected in real time by the liquid level sensor 3. Compare it with the rated full-load liquid level Comparison, using formulas Calculate the heat capacity scaling factor This factor dynamically reflects the ratio between the current medium stock (heat capacity) and the full-load state, providing a quantitative basis for the adaptive adjustment of subsequent control parameters.

[0041] Step S1022: Based on the heat capacity proportional factor and the preset dynamic mapping function, the control parameters of the inner loop control loop are reconstructed to obtain the inner loop reconstructed control parameters, which include proportional, integral gain and differential damping.

[0042] This embodiment is based on the heat capacity ratio factor. With a preset dynamic mapping function, the proportional, integral, and derivative damping of the inner loop PID controller are reconstructed online: based on the reference parameters under full-load liquid level, the gain is automatically adjusted through the mapping function (for example, reducing the proportional and integral gain and increasing the derivative damping when the liquid level decreases) to obtain the inner loop reconstructed control parameters that are adapted to the current heat capacity, thereby suppressing temperature jumps and oscillation overshoot under low water volume conditions and improving the response accuracy of the inner loop to variable heat capacity.

[0043] This embodiment dynamically quantifies the ratio between the current medium volume and the full-load heat capacity by real-time acquisition of liquid level and calculation of the heat capacity proportional factor. Then, based on the heat capacity proportional factor and a preset mapping function, the proportional, integral gain, and differential damping of the inner-loop PID controller are reconstructed online to obtain inner-loop reconstructed control parameters adapted to the current heat capacity. This achieves adaptive adjustment of the inner-loop control parameters according to liquid level fluctuations (heat capacity changes), effectively suppressing temperature jumps and oscillation overshoot under low water volume conditions, significantly improving the inner-loop response accuracy to changing heat capacity, alleviating the problem of slow temperature control caused by capacity lag, and ensuring stable and controllable water tank temperature.

[0044] In some optional implementations, the preset dynamic mapping function in step S1022 above is a nonlinear parameter adjustment function based on the heat capacity scaling factor, and its mathematical form is: , in, For the inner ring reconstruction ratio, Indicates time, To reconstruct the integral gain of the inner loop, For the inner loop, reconstruct the differential damping. This is the proportional reference parameter under full load liquid level. The integral gain reference parameter is the value at full load liquid level. These are the differential damping reference parameters at full load liquid level. This is the heat capacity scaling factor. This is a proportional adjustment function. This is the integral gain adjustment function. This is the differential damping adjustment function.

[0045] This embodiment dynamically correlates the proportional, integral, and derivative gains of the inner-loop PID controller with the current heat capacity state by pre-setting a nonlinear parameter adjustment function based on the heat capacity proportional factor. This allows the inner-loop control parameters to adaptively adjust with liquid level fluctuations (heat capacity changes), effectively suppressing temperature jumps and oscillation overshoot, significantly improving the inner-loop response accuracy to changing heat capacity, alleviating temperature control lag caused by capacity hysteresis, and ensuring stable and controllable temperature of the heat exchange water tank.

[0046] In some optional implementations, the scaling function in the aforementioned preset dynamic mapping function... Integral gain adjustment function and differential damping adjustment function According to the heat capacity ratio factor Determined by the range it falls within, including: Step 1, based on the heat capacity ratio factor And the range where the heat capacity scaling factor threshold is located; if the heat capacity scaling factor Greater than or equal to the high heat capacity scaling factor threshold Then proceed to step two; if the heat capacity ratio factor Greater than the low heat capacity scaling factor threshold And less than the high heat capacity scaling factor threshold Then proceed to step three; if the heat capacity ratio factor Less than or equal to the low heat capacity scaling factor threshold Then proceed to step four; where the high heat capacity scaling factor threshold is... and low heat capacity scaling factor threshold The value is based on the rated design parameters (such as pipeline volume and rated working liquid level) and is obtained through experimental calibration and optimization. It is used to divide the characteristic range of different heat capacity states.

[0047] Step two: Identify the area as a high liquid level zone and use a benchmark mapping strategy to obtain the proportional adjustment function. Integral gain adjustment function and differential damping adjustment function .

[0048] This embodiment is... At this time, the liquid level in heat exchange tank 2 is in the high liquid level zone, indicating sufficient heat capacity and strong anti-interference ability. A reference mapping strategy can be adopted, for example... , , This avoids redundant adjustments and maintains the response speed and accuracy of the full-load baseline PID.

[0049] Step 3: Determine the liquid level as medium and use a smooth nonlinear adjustment strategy to obtain the proportional adjustment function. Integral gain adjustment function and differential damping adjustment function .

[0050] This embodiment is... At this point, the liquid level in heat exchange tank 2 is in the middle level zone, indicating that the heat capacity is moderate. A balance needs to be struck between response speed and stability. This can be achieved using a quadratic nonlinear mapping, such as a parabolic adjustment, to make the parameters follow the changes in temperature. Reduce smoothness transition. For example, the scaling function is obtained using the following formula. Integral gain adjustment function and differential damping adjustment function : , in, This is the proportional attenuation factor. This is the integral gain attenuation coefficient. These are the differential damping enhancement coefficients. All three coefficients are preset constants and can be calibrated experimentally. For example... , , .

[0051] Step four: Identify the area as a low liquid level zone and use a strong suppression strategy to obtain the proportional adjustment function. Integral gain adjustment function and differential damping adjustment function .

[0052] This embodiment is... At this point, the liquid level in heat exchange tank 2 is in the low-level zone, indicating that the heat capacity is too small and it is sensitive to power changes. Forced safety derating is required to prioritize suppressing overshoot and thermal breakdown. For example, the proportional adjustment function is obtained using the following formula. Integral gain adjustment function and differential damping adjustment function : , in, This is the proportional limiting coefficient. This is the integral gain limiting factor. These are the differential damping enhancement coefficients. All three coefficients are preset constants and can be calibrated experimentally. For example... , , .

[0053] This embodiment uses a preset dynamic mapping function to adjust the PID control parameters according to the range of the heat capacity proportional factor (high, medium, and low liquid level zones): in the high liquid level zone, a reference mapping is used to maintain full-load accuracy; in the medium liquid level zone, a smooth nonlinear transition is used to balance the response and stability; and in the low liquid level zone, a strong suppression strategy is used to prevent overshoot and thermal breakdown. Overall, the inner-loop parameters dynamically adapt to the heat capacity, effectively suppressing oscillations and temperature jumps under varying liquid levels, significantly improving temperature control accuracy and system safety, and ensuring stable organ perfusion temperature.

[0054] In some optional implementations, the process of calculating the actual feedforward temperature compensation based on the outlet temperature, return water temperature, and pipeline flow rate in step S104 mainly includes: Step S1041: Calculate the transient heat load based on the outlet temperature, return water temperature, pipeline flow rate, specific heat capacity, and fluid density.

[0055] This embodiment is based on the outlet temperature. Return water temperature Pipeline flow Specific heat capacity and fluid density Calculate the transient heat load. For example, the transient heat load is calculated using the following formula. : , in, The temperature difference between the inlet and outlet water reflects the intensity of the heat load. Calculating transient heat load can quantify the dynamic energy of external thermal shocks such as organ access, providing a physical basis for feedforward compensation.

[0056] Step S1042: Calculate the ideal feedforward temperature compensation based on the transient heat load and the preset basic feedforward conversion coefficient.

[0057] For example, the ideal feedforward temperature compensation is calculated using the following formula. :

[0058] , in, These are the preset basic feedforward conversion coefficients.

[0059] This embodiment generates an ideal feedforward temperature compensation by multiplying the transient heat load by a preset basic feedforward conversion coefficient. This is achieved by using a feedforward mechanism to proactively offset external thermal disturbances and by utilizing fluid dynamics data to overcome pipeline transmission delays, thus preventing significant deviations in outlet temperature.

[0060] Step S1043: Generate the current liquid level weight based on the liquid level and a preset weight function.

[0061] This embodiment is based on liquid level. The current liquid level weight is generated by a preset weighting function. This allows for dynamic adaptation to the heat capacity status (liquid level) of the heat exchange water tank 2, preventing damage to small heat capacity systems due to excessive feedforward.

[0062] Step S1044: Calculate the actual feedforward temperature compensation based on the ideal feedforward temperature compensation and the current liquid level weight.

[0063] For example, the actual feedforward temperature compensation is calculated using the following formula. : , Among them, the current liquid level weight The higher the liquid level, the closer the weight is to 1; the lower the liquid level, the lower the weight is.

[0064] Due to its nonlinear characteristics, this embodiment does not directly use the ideal feedforward temperature compensation amount. Instead, it multiplies the ideal feedforward temperature compensation amount by the current liquid level weight to calculate the actual feedforward temperature compensation amount, which is used to suppress the feedforward intensity at low liquid levels, prevent thermal breakdown, and ensure system safety while resisting disturbances.

[0065] This embodiment calculates transient heat load by collecting outlet water temperature, return water temperature, and pipeline flow rate, combined with specific heat capacity and density. An ideal feedforward compensation is generated using a conversion coefficient, and its intensity is dynamically adjusted based on liquid level weights to ultimately obtain the actual feedforward temperature compensation. This embodiment proactively offsets external thermal shocks such as organ access, overcomes pipeline transmission delays, and prevents excessive feedforward at low liquid levels from causing thermal breakdown. This improves system immunity while ensuring system safety and maintaining stable and controllable heat exchange tank temperature.

[0066] In some optional implementations, the preset weighting function in step S1043 above takes the heat capacity ratio factor and the liquid level change rate as input parameters. The heat capacity ratio factor is calculated from the liquid level and the rated full-load liquid level, and the liquid level change rate is the rate of change of the heat capacity ratio factor over time.

[0067] In this embodiment, the preset weighting function takes the heat capacity ratio factor and the liquid level change rate as input parameters. For example, the setting rules for the preset weighting function are as follows: when At this time, the liquid level in heat exchange water tank 2 is in the high liquid level zone. At this time, the heat capacity is sufficient, and the current liquid level weight can be taken as the maximum value, for example, the weight is 1, to fully retain the ideal feedforward compensation amount and make full use of the anti-interference ability of the large heat capacity.

[0068] when At this time, the liquid level in heat exchange tank 2 is in the middle level zone, and the heat capacity is at a moderate level. The preset weighting function is determined by the heat capacity proportional factor and the liquid level change rate. The liquid level change rate is the rate at which the heat capacity proportional factor changes with time, calculated using a differential algorithm. Therefore, the current liquid level weight decreases as the liquid level decreases (the lower the liquid level, the smaller the basic weight). Simultaneously, as the liquid level changes faster (whether rising or falling), the weight is further weakened to balance response speed and stability, avoiding oscillations caused by dynamic disturbances.

[0069] when In the heat exchange tank 2, the liquid level is in the low liquid level zone. At this time, the heat capacity is low. The preset weight function adopts a strong suppression strategy: actively reducing the intensity of the feedforward and setting a minimum weight (e.g., not lower than 0.1) to prevent runaway. If the liquid level is slightly higher than the extremely low threshold, the weight is adjusted slightly with the liquid level but strictly limited to avoid temperature jumps, overshoots or even thermal breakdowns caused by excessive feedforward in small heat capacity systems, ensuring that system safety is still the core in low liquid level conditions.

[0070] This embodiment addresses the shortcomings of traditional liquid level judgment methods, such as susceptibility to water surface fluctuations and the inability to reflect thermodynamic inertia while only considering geometric height, by introducing a heat capacity ratio factor to transform the physical liquid level into a normalized heat capacity index. This not only filters out sensor noise and avoids misjudgments but also accurately quantifies the actual heat absorption or dissipation capacity of the current water volume. Based on the heat capacity ratio factor and the rate of change of liquid level, the liquid level is divided into high, medium, and low zones: the high liquid level zone retains the maximum weight for full feedforward compensation, fully utilizing the large heat capacity to resist interference; the medium liquid level zone dynamically weakens the weight as the liquid level decreases and changes rapidly, balancing response and stability; the low liquid level zone employs a strong suppression strategy with a minimum weight to prevent excessive compensation from causing temperature jumps or thermal breakdown. Overall, the feedforward intensity is adaptively adjusted according to the heat capacity state, effectively improving temperature control accuracy and safety.

[0071] In some optional embodiments, the organ perfusion temperature control method based on cascade control provided by the present invention further includes: Step S109: Obtain the temperature of the infusion fluid. Determine whether the temperature of the infusion fluid meets the standard based on the absolute value of the difference between the infusion fluid temperature and the final target temperature and a preset deviation range. If the absolute value of the difference between the infusion fluid temperature and the final target temperature is less than or equal to the preset deviation range, proceed to step S110; if the absolute value of the difference between the infusion fluid temperature and the final target temperature is greater than the preset deviation range, proceed to step S111. In this embodiment, the temperature of the infusion fluid is acquired by a fourth temperature sensor, such as... Figure 3As shown, the fourth temperature sensor 12 is installed in the perfusion fluid circulation pipeline between the organ compartment 1 and the oxygenator 10 to collect the perfusion fluid temperature. Step S109 requires calculating the absolute value of the difference between the perfusion fluid temperature and the final target temperature of the inner loop control loop obtained in step S106, and judging whether the adjusted perfusion fluid temperature meets the target based on the preset deviation range, so as to monitor the degree of deviation between the perfusion fluid temperature and the target in real time and provide a quantitative basis for subsequent judgment and adjustment.

[0072] Step S110: Determine that the temperature of the infusion fluid meets the standard.

[0073] When the absolute value of the difference between the perfusion fluid temperature and the final target temperature is less than or equal to the preset deviation range, the perfusion fluid temperature is determined to meet the standard, that is, the current temperature is confirmed to be stable within the allowable range, meeting the safety requirements of organ perfusion, and no additional adjustment is required to maintain the current power of the semiconductor cooling chip 8.

[0074] Step S111: Determine that the temperature of the infusion fluid does not meet the standard.

[0075] When the absolute value of the difference between the injection fluid temperature and the final target temperature is greater than the preset deviation range, it is determined that the temperature has not met the standard. The injection fluid temperature can be adjusted in time to push the temperature back to the target value, ensuring that the injection fluid temperature is accurate and controllable.

[0076] This embodiment achieves precise and stable control of organ perfusion fluid temperature by adjusting the power of the semiconductor cooling chip to achieve the final target temperature of the inner loop control circuit, and then combining this with real-time determination of the perfusion fluid temperature, effectively ensuring organ viability and perfusion safety.

[0077] In some optional embodiments, when step S111 determines that the infusion fluid temperature has not met the standard, the method further includes: Step S112: Determine whether the difference between the infusion fluid temperature and the final target temperature is less than or equal to the small deviation threshold. If the difference between the infusion fluid temperature and the final target temperature is less than or equal to the small deviation threshold, proceed to step S113; if the difference between the infusion fluid temperature and the final target temperature is greater than the small deviation threshold, proceed to step S114.

[0078] In this embodiment, when the temperature of the infusion fluid is determined to be below the target, the deviation between the temperature of the infusion fluid and the final target temperature is recorded for further adjustment.

[0079] Step S113: Adjust the differential damping in the inner loop reconfiguration control parameters.

[0080] When the difference between the injection fluid temperature and the final target temperature is less than or equal to the small deviation threshold, it indicates that the current temperature deviation is very small and small deviation correction can be performed. This is achieved by adjusting the differential damping coefficient in the inner loop reconstruction control parameters, for example, by increasing the differential damping, to enhance the rapid suppression of the inner loop temperature deviation and indirectly correct the injection fluid temperature.

[0081] Step S114: Determine whether the difference between the infusion fluid temperature and the final target temperature is greater than zero. If the difference between the infusion fluid temperature and the final target temperature is greater than zero, proceed to step S115; if the difference between the infusion fluid temperature and the final target temperature is less than zero, proceed to step S116.

[0082] In this embodiment, when the difference between the temperature of the injection fluid and the final target temperature is greater than the small deviation threshold, it indicates that the current temperature deviation is large, and a large deviation correction is performed. The deviation direction is recorded: a positive deviation indicates that the injection fluid is overheated, and a negative deviation indicates that the injection fluid is undercooled.

[0083] Step S115: Reduce the actual feedforward temperature compensation amount.

[0084] When the difference between the injection fluid temperature and the final target temperature is greater than zero, it indicates that the injection fluid is overheated, and the actual feedforward temperature compensation needs to be reduced, for example, by reducing the preset basic feedforward conversion coefficient. The specific reduction ratio can be calibrated based on organ perfusion scenario experiments, and then the ideal feedforward temperature compensation amount and the actual feedforward temperature compensation amount can be recalculated to temporarily lower the final target temperature of the inner loop control loop.

[0085] Step S116: Increase the actual feedforward temperature compensation amount.

[0086] When the difference between the injection fluid temperature and the final target temperature is less than zero, it indicates that the injection fluid is too cold, and the actual feedforward temperature compensation needs to be increased, for example, by increasing the preset basic feedforward conversion coefficient. The specific increase ratio can be calibrated based on organ perfusion scenario experiments, and then the ideal feedforward temperature compensation amount and the actual feedforward temperature compensation amount can be recalculated to temporarily increase the final target temperature of the inner loop control loop.

[0087] At this time, a short-term calibration of the outer loop control loop can also be triggered, that is, shorten the outer loop data sampling period, reacquire the outlet temperature, the return water temperature of the heat exchange water tank, and the pipeline flow between the temperature change zone of the heat exchange water tank and the oxygenator, and after correction, re-execute steps S104-S109 until the injection fluid temperature reaches the standard.

[0088] This embodiment improves temperature control accuracy through tiered correction when the target is not met: for small deviations, the inner loop differential damping is adjusted to enhance suppression; for large deviations, the feedforward compensation is adjusted according to overheating / overcooling; simultaneously, a short-term calibration of the outer loop (shortening the data resampling cycle) is triggered to dynamically correct the target. Overall, it achieves precise deviation positioning and rapid response, ensuring efficient achievement of perfusion fluid temperature targets and enhancing the stability of organ perfusion temperature control and organ perfusion safety.

[0089] In some optional implementations, the process of calculating the base power based on the final target temperature and the inner loop reconfiguration control parameters in step S107 mainly includes: Step S1071: Calculate the temperature deviation based on the difference between the final target temperature and the internal temperature of the water tank.

[0090] This embodiment calculates the difference between the final target temperature of the inner ring and the actual temperature inside the water tank to obtain the temperature control deviation.

[0091] Step S1072: Calculate the power based on the inner loop reconfiguration control parameters and temperature deviation to obtain the base power.

[0092] This embodiment combines the temperature deviation with the PID parameters of the liquid level adaptive reconstruction, and synthesizes the basic power through PID calculation.

[0093] For example, the base power is calculated using the following formula. : , in, For temperature deviation, For the accumulation of deviation, This represents the previous cycle deviation, which can be initialized to 0 when there is no previous cycle deviation.

[0094] This embodiment calculates the temperature deviation in real time and combines it with the PID parameters that are adaptive to the liquid level. The inner loop quickly generates a precise base power, effectively responds to transient changes in the semiconductor cooling chip, suppresses oscillation overshoot caused by liquid level fluctuations, and significantly improves the accuracy and stability of temperature control in the heat exchange water tank.

[0095] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0096] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for controlling organ perfusion temperature based on cascade control, characterized in that, An organ perfusion device is used, comprising an organ chamber, a heat exchange water tank, an oxygenator, and a semiconductor refrigeration chip. The organ chamber is used to preserve organs, the heat exchange water tank is used to store water, and the water is circulated to indirectly exchange heat with the perfusion fluid in the organ chamber to control the temperature of the perfusion fluid. The oxygenator is used to perform gas exchange, and the semiconductor refrigeration chip is used to regulate the temperature of the medium in the heat exchange water tank. The method includes: The outlet temperature of the heat exchange water tank, the return water temperature of the heat exchange water tank, and the pipeline flow rate between the heat exchange water tank and the temperature change zone of the oxygenator are obtained using the outer loop control loop. The internal temperature of the heat exchange water tank and the liquid level of the heat exchange water tank are obtained using the inner loop control loop. Calculate the heat capacity proportional factor based on the liquid level and the rated full-load liquid level; reconstruct the control parameters of the inner loop control loop based on the heat capacity proportional factor and the preset dynamic mapping function to obtain the inner loop reconstructed control parameters, which include proportional, integral gain and differential damping. The controller parameters in the inner loop control loop are updated based on the inner loop reconfiguration control parameters. The actual feedforward temperature compensation is calculated based on the outlet temperature, the return water temperature, and the pipeline flow rate. The base target temperature is calculated based on the outlet temperature and the preset outlet temperature. The final target temperature of the inner loop control loop is generated based on the actual feedforward temperature compensation and the basic target temperature. The base power is calculated based on the final target temperature and the inner loop reconfiguration control parameters; Based on the aforementioned base power, a base power adjustment command is generated and output to the drive circuit to drive and adjust the power of the semiconductor cooling chip. The preset dynamic mapping function is a nonlinear parameter adjustment function based on the heat capacity scaling factor, and its mathematical form is: ， in, For the inner ring reconstruction ratio, Indicates time, To reconstruct the integral gain of the inner loop, For the inner loop, reconstruct the differential damping. This is the proportional reference parameter under full load liquid level. The integral gain reference parameter is the value at full load liquid level. These are the differential damping reference parameters at full load liquid level. This is the heat capacity scaling factor. This is a proportional adjustment function. This is the integral gain adjustment function. This is the differential damping adjustment function.

2. The method according to claim 1, characterized in that, The proportional adjustment function The integral gain adjustment function and the differential damping adjustment function According to the heat capacity ratio factor Determined by the range it falls within, including: Based on the heat capacity ratio factor The range in which the threshold for the heat capacity proportionality factor is determined; If the heat capacity ratio factor If the value is greater than or equal to the high heat capacity scaling factor threshold, it is determined to be a high liquid level zone, and the scaling adjustment function is obtained using a benchmark mapping strategy. The integral gain adjustment function and the differential damping adjustment function ; If the heat capacity ratio factor If the value is greater than the low heat capacity proportionality factor threshold but less than the high heat capacity proportionality factor threshold, it is determined to be in the middle liquid level zone, and the proportional adjustment function is obtained by using a smooth nonlinear adjustment strategy. The integral gain adjustment function and the differential damping adjustment function ; If the heat capacity ratio factor If the value is less than or equal to the low heat capacity scaling factor threshold, it is determined to be a low liquid level zone, and a strong suppression strategy is used to obtain the scaling adjustment function. The integral gain adjustment function and the differential damping adjustment function .

3. The method according to claim 1, characterized in that, The calculation of the actual feedforward temperature compensation based on the outlet temperature, the return water temperature, and the pipeline flow rate includes: The transient heat load is calculated based on the outlet temperature, the return water temperature, the pipeline flow rate, the specific heat capacity, and the fluid density. The ideal feedforward temperature compensation is calculated based on the transient heat load and the preset basic feedforward conversion coefficient. The current liquid level weight is generated based on the liquid level and a preset weighting function; The actual feedforward temperature compensation is calculated based on the ideal feedforward temperature compensation and the current liquid level weight.

4. The method according to claim 3, characterized in that, The preset weighting function takes the heat capacity ratio factor and the liquid level change rate as input parameters. The heat capacity ratio factor is calculated from the liquid level and the rated full-load liquid level, and the liquid level change rate is the rate of change of the heat capacity ratio factor over time.

5. The method according to claim 1, characterized in that, Also includes: The temperature of the infusion fluid is obtained, and the absolute value of the difference between the infusion fluid temperature and the final target temperature, along with a preset deviation range, is used to determine whether the infusion fluid temperature meets the standard. If the absolute value of the difference between the infusion fluid temperature and the final target temperature is less than or equal to a preset deviation range, then the infusion fluid temperature is determined to meet the standard. If the absolute value of the difference between the temperature of the infusion fluid and the final target temperature is greater than the preset deviation range, it is determined that the temperature of the infusion fluid has not met the standard.

6. The method according to claim 5, characterized in that, When it is determined that the temperature of the infusion fluid does not meet the standard, it is determined whether the difference between the temperature of the infusion fluid and the final target temperature is less than or equal to the small deviation threshold. If the difference between the infusion fluid temperature and the final target temperature is less than or equal to the small deviation threshold, then the differential damping in the inner loop reconstruction control parameters is adjusted. If the difference between the temperature of the infusion fluid and the final target temperature is greater than the small deviation threshold, then it is determined whether the difference between the temperature of the infusion fluid and the final target temperature is greater than zero. If the difference between the infusion fluid temperature and the final target temperature is greater than zero, then the actual feedforward temperature compensation amount is reduced. If the difference between the infusion fluid temperature and the final target temperature is less than zero, then the actual feedforward temperature compensation amount is increased.

7. The method according to claim 1, characterized in that, The calculation of the base power based on the final target temperature and the inner loop reconfiguration control parameters includes: The temperature deviation is obtained by calculating the difference between the final target temperature and the internal temperature of the water tank. The power is calculated based on the inner loop reconfiguration control parameters and the temperature deviation to obtain the base power.

8. An organ perfusion temperature control system based on cascade control, characterized in that, include: An organ perfusion device and a main control unit; wherein the organ perfusion device is used to control the temperature of the perfusion fluid through heat exchange, and the main control unit is used to execute the organ perfusion temperature control method based on cascade control as described in any one of claims 1-7.

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