Drive and step feedback system for memory wire motor of insulin pump

Abstract

The present application belongs to the field of medical instrument control, and particularly relates to a driving and stepping feedback system of a memory metal wire motor for an insulin pump. The system is aimed at solving the problems of shape memory alloy driving hysteresis and low precision of drug delivery, and comprises a microcontroller, a driving control circuit, a dynamic parameter sampling branch, a physical limit feedback component and an adaptive logic module. The microcontroller drives the alloy wire in stages; the dynamic parameter sampling branch utilizes resistance change to determine deformation to form a first feedback loop; the physical limit feedback component confirms displacement to form a second feedback loop. The adaptive logic module fuses and judges the double-loop signals and executes error correction compensation. The present application overcomes the non-linear deformation deviation through double closed-loop feedback, improves the precision of drug delivery, and realizes mechanism jamming early warning, system miniaturization and silent operation.

Description

Technical Field

[0001] This invention belongs to the field of medical device control, specifically relating to a drive and stepping feedback system for a memory metal wire motor used in insulin pumps. Background Technology

[0002] With the continuous evolution of modern clinical medical technology, micro-dose delivery systems are playing an increasingly crucial role in the treatment of metabolic diseases. These sophisticated devices place extremely stringent requirements on the integration of the drive system and the accuracy of infusion, aiming to ensure that extremely small doses of drugs can be delivered continuously and stably to the body's physiological feedback system.

[0003] In the pursuit of extremely high power-to-weight ratio and quiet operation, shape memory alloys, with their unique phase change driving mechanism, have become a core alternative to traditional electromagnetic motors. The basic principle lies in using a controllable current to excite a microscopic phase change within the material, causing the alloy to undergo macroscopic deformation at a specific temperature threshold, thereby driving a micro-mechanical actuator in a drug delivery device to complete a quantitative physical step.

[0004] However, due to the inherent hysteresis characteristics of shape memory alloys and the complex environmental heat exchange process, the energy input of the drive system and the displacement output of the end mechanism exhibit extremely strong nonlinear coupling, making it difficult for a single control model to accurately capture the actual physical state of the alloy wire. This uncertainty is further exacerbated by performance fatigue caused by long-term material use and the influence of external resistance fluctuations, leading to a severe mismatch between drive commands and physical displacement.

[0005] When the drive system cannot verify in real time whether the piston mechanism has truly crossed the preset mechanical stroke, any step loss caused by blockage of the mechanism or insufficient material deformation will lead to a deviation of the drug delivery dose from the preset value. The resulting infusion error will accumulate and form a huge safety risk in micro-dose scenarios, directly threatening the clinical reliability of medical devices and becoming a technical bottleneck restricting the realization of high-precision closed-loop control of intelligent micro-pumps. Summary of the Invention

[0006] The present invention aims to provide a drive and stepping feedback system for a shape memory metal wire motor for an insulin pump, which aims to solve the problems of severe hysteresis, obvious nonlinear deformation characteristics, low drug delivery accuracy and infusion safety risks caused by open-loop control in existing shape memory alloy drive schemes.

[0007] The present invention provides a drive and step feedback system for a memory metal wire motor for an insulin pump, comprising: a microcontroller unit, a drive control circuit, a dynamic parameter sampling branch, a physical limit feedback component, and an adaptive logic control module.

[0008] The microcontroller unit generates a drive control signal with a frequency range of 20 kHz to 50 kHz and outputs this signal to the drive control circuit to drive the shape memory alloy wire through the current-thermal effect. The drive control circuit includes a power stage composed of low-on-resistance power MOSFETs, which receives the drive control signal and provides a controlled current to the shape memory alloy wire. The driving process is divided into three stages: a preheating stage, where the shape memory alloy wire reaches the phase transformation critical temperature by rapidly increasing the current; a triggering stage, where the shape memory alloy wire shrinks from martensite to austenite by precisely controlling the pulse width; and a sustaining stage, where the physical deformation of the shape memory alloy wire is maintained in a low-power mode.

[0009] Furthermore, the dynamic parameter sampling branch is connected in series in the drive control circuit loop, and it includes a high-precision sampling resistor and a filter capacitor connected in parallel with the sampling resistor. The microcontroller unit acquires the voltage and current data across the shape memory alloy wire in real time through its built-in high-speed analog-to-digital converter, and calculates the real-time resistance value of the shape memory alloy wire based on the voltage-to-current ratio. This dynamic parameter sampling branch constitutes the first feedback loop, which utilizes the physical characteristic that the resistance value of the shape memory alloy wire decreases linearly during the shrinkage phase transition process, and determines the percentage of physical deformation of the shape memory alloy wire by monitoring the slope and magnitude of the resistance value decrease.

[0010] Furthermore, a physical limit feedback component is located at the end of the motion path of the push rod mechanism, and it includes a miniature physical touch sensor. When the shape memory alloy wire retracts and drives the pawl mechanism to complete one preset length of physical step movement, the miniature physical touch sensor is pressed and generates a level transition signal. This physical limit feedback component constitutes a second feedback loop, used to provide a physical confirmation signal that the mechanical displacement has been truly completed.

[0011] In one embodiment of the present invention, an adaptive logic control module is integrated into a microcontroller unit for logically fusing and determining the resistance characteristic signal provided by the first feedback loop and the level transition signal provided by the second feedback loop. The system has a preset time threshold of 500 milliseconds. If the system detects that the resistance decrease characteristic of the shape memory alloy wire meets the preset contraction threshold, but does not receive a level transition signal from the micro-physical touch sensor within 500 milliseconds, the adaptive logic control module determines that the current state is either mechanical blockage or insufficient stroke due to fatigue of the shape memory alloy wire.

[0012] Furthermore, the adaptive logic control module includes error correction and compensation logic. After determining that the travel is insufficient, the system automatically increases the voltage, current, or power parameters of the drive control signal for the next drive sequence, with the increase set to 3% of the current reference value, to improve the drive power. If the physical limit feedback component still fails to trigger a valid level transition signal after the system performs three consecutive compensation operations, the microcontroller unit stops the drive output and outputs a mechanical blockage error command to the external terminal.

[0013] In one embodiment of the present invention, the microcontroller unit acquires ambient temperature data through an ambient temperature sensor during the initialization phase, and dynamically sets the reference values ​​of voltage, current, or power parameters of the initial drive control signal according to an ambient temperature compensation algorithm. The sampling resistor in the drive control circuit is set to an accuracy level of ±0.1% to ensure that the capture of changes in the resistance of the shape memory alloy wire during dynamic sampling reaches the milliohm level.

[0014] Furthermore, the system's power stage circuit employs gallium nitride power switches to ensure that the temperature rise of the drive board itself remains within 1 degree Celsius under high-current heating conditions, thereby preventing the heat generated by the drive circuit itself from interfering with the ambient temperature detection of the shape memory alloy wire. Through the coordinated operation of dual closed-loop models, the system controls the accuracy error of a single drug delivery step within ±2%.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are as follows: This invention fundamentally overcomes the nonlinear deformation deviation of shape memory alloy wires during insulin infusion caused by hysteresis and environmental temperature drift during the process by constructing a dual closed-loop feedback system based on dynamic resistance characteristics and physical displacement signals, achieving extremely high-precision drug delivery on the order of 0.05 to 0.1 units. This invention eliminates the bulky permanent magnet, coil, and encoder structures found in traditional drive devices, utilizing the dual driving and sensing properties of shape memory alloy wires to significantly reduce the system's physical size and achieve completely silent operation. Simultaneously, by introducing a compensation algorithm that uses both resistance characteristics and physical limits for dual verification, the system can identify and warn of fault states such as mechanical blockage, shape memory alloy wire breakage, or material fatigue in real time, greatly improving the safety and reliability of Level 2 medical devices and ensuring consistent insulin pump infusion under complex environments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall technical architecture of the drive and step feedback system for the memory metal wire motor for insulin pumps proposed in this invention. Figure 2 This is a schematic diagram of the core principle framework of the dual closed-loop feedback control based on the dynamic characteristics of resistance and the physical displacement signal in this invention. Figure 3This is a logical flow diagram of the three-stage division of the shape memory alloy wire driving process in this invention; Figure 4 This is a schematic diagram of the multi-level interaction relationship and data flow between the microcontroller unit, the drive control circuit and the dual feedback loop in this invention; Figure 5 This is a schematic diagram of the physical limit feedback component; The markings in the accompanying drawings include: protection resistor 10, first contact 20, claw 30, second contact 40, and shape memory alloy wire 50. Detailed Implementation

[0017] The following detailed description illustrates the specific implementation method: The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] In the accompanying drawings, the size of constituent elements, the thickness of layers, or areas may sometimes be exaggerated for clarity. Therefore, any implementation of this disclosure is not necessarily limited to the dimensions shown in the drawings, and the shapes and sizes of the components in the drawings do not reflect true proportions. Furthermore, the drawings schematically illustrate ideal examples, and any implementation of this disclosure is not limited to the shapes or values ​​shown in the drawings.

[0019] Reference Figure 1 , Figure 1 This is a schematic diagram of the overall technical architecture of the drive and stepping feedback system for the memory metal wire motor used in insulin pumps proposed in this invention. Figure 1 As shown, the system includes: a microcontroller unit, a drive control circuit, a dynamic parameter sampling branch, a physical limit feedback component, and an adaptive logic control module.

[0020] In this embodiment, the microcontroller unit acts as the control center of the system, outputting the drive control signal to the drive control circuit via GPIO pins. Upon receiving the drive control signal, the drive control circuit converts electrical energy into a controlled current flowing through the shape memory alloy wire (achieving controlled current switching and power control). Under the influence of the current's thermal effect, the shape memory alloy wire undergoes atomic lattice structure reorganization, resulting in physical deformation that drives the insulin pump's push rod mechanism to perform the infusion action.

[0021] Reference Figure 3 , Figure 3This is a logical flowchart illustrating the three-stage division of the shape memory alloy wire driving process in this invention. In this embodiment, the microcontroller unit performs a refined timing breakdown of the driving process, specifically dividing it into the following three physical states: The first stage is the preheating stage. In this stage, the microcontroller unit outputs a drive control signal, which drives the control circuit to inject a large current into the shape memory alloy wire. By utilizing the Joule heating effect, the internal temperature of the shape memory alloy wire rapidly rises to the phase transition critical temperature (As point) within a short period of time. This process aims to shorten the system's response delay and establish a preliminary physical state for subsequent deformation actions.

[0022] The second stage is the triggering stage. When the system detects that the shape memory alloy wire has reached the preset physical state, the microcontroller unit controls the amount of heat energy input per unit time through the drive control signal, inducing the shape memory alloy wire to complete the phase transformation from martensite to austenite. During this process, the shape memory alloy wire contracts along its length axis, pulling the pawl mechanism to complete the preset stroke.

[0023] The third stage is the sustaining stage. After the mechanical action is completed, the microcontroller unit switches to a low-power mode and outputs a sustaining current. The heat generated by this current reaches a dynamic thermal equilibrium with the ambient heat dissipation, allowing the shape memory alloy wire to maintain its physical contraction deformation in the austenitic state, ensuring the positional stability of the push rod mechanism during the injection interval.

[0024] Reference Figure 2 and Figure 4 , Figure 2 This is a schematic diagram illustrating the core principle framework of the dual closed-loop feedback control based on the dynamic characteristics of resistance and the physical displacement signal in this invention. In this embodiment, the system constructs a multi-level interactive monitoring system consisting of a first feedback loop and a second feedback loop.

[0025] The first feedback loop is implemented by a dynamic parameter sampling branch. This branch is connected in series in the power loop of the drive control circuit and internally includes a high-precision sampling resistor and a low-pass filter capacitor connected in parallel with the sampling resistor. The accuracy of the sampling resistor is set to ±0.1%. The microcontroller unit uses a built-in high-speed analog-to-digital converter (ADC) to acquire, in real time, the voltage drop across the shape memory alloy wire and the current flowing through the sampling resistor at a sampling frequency of at least 10kHz.

[0026] In this embodiment, the microcontroller unit calculates the transient resistance value of the shape memory alloy wire in real time according to Ohm's law (R=U / I). As the shape memory alloy wire shrinks towards austenite, the change in its physical geometry causes a linear decrease in resistance. The microcontroller unit determines the percentage of physical deformation of the shape memory alloy wire by monitoring the slope (dR / dt) and cumulative decrease in resistance. This resistance feedback mechanism enables non-contact real-time monitoring of the microscopic phase transformation process of the alloy wire, forming the first layer of accuracy assurance for the system.

[0027] The second feedback loop is implemented by a physical limit feedback component. This component is located at the end of the motion path of the push rod mechanism, and its core element is a miniature physical touch sensor (i.e., the first contact 20). When the shape memory alloy wire retracts, causing the claw mechanism to complete a full physical step (e.g., corresponding to 0.05 or 0.1 units of insulin dispensing), the push rod or linkage mechanism physically touches the miniature physical touch sensor, causing its contact to close. At this time, the sensor generates a definite level transition signal and sends it back to the interrupt capture pin of the microcontroller unit. This signal serves as a "final steady-state confirmation" of the actual completion of the mechanical displacement, eliminating false alarms that may occur due to the hysteresis effect of the shape memory alloy wire.

[0028] The specific structure of the physical limit feedback component in this embodiment is as follows: Figure 5 As shown, the device includes: a protective resistor 10, a first contact 20, a second contact 40, and a claw 30. One end of the protective resistor 10 is connected to a power supply Vdd, and the other end is connected to the first contact 20 (which is the aforementioned miniature physical touch sensor, functioning to connect to the second contact 40 when in contact with the claw 30). The claw 30 is hinged to the second contact 40, and one end of the second contact 40 is grounded. The pins of the microcontroller unit are connected to the first contact 20. One end of the shape memory alloy wire 50 is fixed to one end of the claw 40, and the other end of the shape memory alloy wire 50 is connected to and fixed to the output of the drive control circuit. After the shape memory alloy wire 50 is energized, it forms a circuit by grounding through the second contact 40 and begins to contract. During the contraction process, the other end of the claw 30 rotates under the contraction deformation of the shape memory alloy wire 50, and after completing the stepping action, it connects to the first contact 20, causing the voltage of the power supply Vdd to be pulled down at the first contact 20. The microcontroller unit completes the acquisition of the signal indicating that this action has been completed. This method is simple and reliable. The second contact 40 cooperates with the first contact 20 and the claw 30 to complete the acquisition of the claw 30's action completion. The claw 30 cooperates with the shape memory alloy wire 50 to not only form the power supply circuit for the shape memory alloy wire 50, but also enable the shape memory alloy wire 50 to drive the claw 30 to move.

[0029] In one embodiment, this application also provides an adaptive logic control module integrated into the firmware layer of the microcontroller unit. The adaptive logic control module is responsible for timing logic fusion of the resistance characteristic signal of the first feedback loop and the level transition signal of the second feedback loop. The system has a preset time threshold constant of 500 milliseconds. After a complete drive command is issued, if the microcontroller unit determines through the first feedback loop that the resistance decrease characteristic of the shape memory alloy wire meets the preset contraction threshold (indicating a phase transition has occurred), but within the following 500 milliseconds, the capture register of the microcontroller unit does not receive a level transition signal from the physical limit feedback component, the adaptive logic control module automatically determines the current physical condition as abnormal; if the capture register of the microcontroller unit receives a level transition signal from the physical limit feedback component, it is in a normal state. This abnormal state specifically points to mechanical blockage caused by foreign objects outside the mechanism, or insufficient effective stroke due to material fatigue caused by multiple cycles of the alloy wire.

[0030] In this embodiment, the adaptive logic control module includes error correction and compensation logic after brute-force disassembly. Once insufficient travel is determined, the system will not immediately report a fault, but will automatically activate the enhanced drive mode. In the next drive sequence, the microcontroller unit will increase the reference value of the voltage, current, or power parameters of the drive control signal by 3%. This small, step-by-step increase in power level attempts to overcome instantaneous mechanical resistance. If the physical limit feedback component still fails to trigger a valid level transition signal after three consecutive compensation operations (cumulative increase of 9%), the microcontroller unit will forcibly stop all power output according to the safety redundancy principle and output a mechanical blockage error command to an external terminal (such as a mobile app or pump display), while simultaneously locking the infusion program.

[0031] In one implementation, this application further enhances the environmental stability of the system through extreme hardware-level optimization. The power stage circuit in the drive control circuit uses gallium nitride (GaN) power switches. Compared to traditional silicon-based MOSFETs, GaN switches have extremely low inter-electrode capacitance and conduction losses, and generate very little waste heat under conditions of frequent high-current switching.

[0032] This extremely low thermal radiation design ensures that the ambient temperature data acquired by the microcontroller unit during the initialization phase via the ambient temperature sensor is highly accurate, avoiding thermal drift interference caused by the heat generated by the drive circuit itself on the ambient temperature compensation algorithm. Based on the acquired ambient temperature, the microcontroller unit dynamically calculates and sets the reference values ​​for the voltage, current, or power parameters of the initial drive control signal. For example, in low-temperature environments (such as a 4-degree Celsius refrigeration environment), the system automatically increases the initial reference value of the preheating stage to counteract the intense heat exchange between the alloy wire and the environment, reducing the accuracy error of single-dose administration steps under different extreme environments.

[0033] Thus, this application, through the dual closed-loop synergy of dynamic resistance characteristics and physical displacement signals, not only achieves high-precision compensation for the nonlinear characteristics of shape memory alloy wires, but also constructs an extremely rigorous medical drug delivery safety closed loop through multi-level feedback confirmation and automatic error correction mechanisms. While eliminating the bulky electromagnetic drive structure and achieving completely silent operation, the system ensures highly consistent insulin infusion, providing solid engineering support for the reliability of long-term wearable medical devices.

[0034] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus, or computer program products. Therefore, embodiments of this application can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects.

[0035] While preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Finally, it should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0036] The above are merely embodiments of the present invention. The invention is not limited to the fields covered by these embodiments. Commonly known structures and characteristics in the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are able to access all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A drive and step feedback system for a memory metal wire motor used in an insulin pump, characterized in that, include: The microcontroller unit is used to output drive control signals; A drive control circuit, connected to the microcontroller unit, is used to receive the drive control signal and provide a controlled current to the shape memory alloy wire; A dynamic parameter sampling branch, connected in series in the drive control circuit, is used to collect the real-time resistance value of the shape memory alloy wire and form the first feedback loop; The physical limit feedback component is located at the end of the motion path of the push rod mechanism. It is used to provide a mechanical displacement confirmation signal through the generated level transition signal and to form a second feedback loop. An adaptive logic control module, integrated in the microcontroller unit, is used to perform logical fusion judgment on the resistance characteristic signal provided by the first feedback loop and the level transition signal provided by the second feedback loop, and adjust the drive control signal according to the judgment result.

2. The driving and stepping feedback system for the shape memory wire motor of the insulin pump according to claim 1, characterized in that, The drive control signal output by the microcontroller unit is used to control the voltage, current and power parameters of the output current of the drive control circuit.

3. The driving and stepping feedback system for the shape memory wire motor of the insulin pump according to claim 1, characterized in that, The drive control circuit divides the working stage into a preheating stage, a triggering stage, and a sustaining stage during the drive process. The microcontroller unit controls the parameters of the drive control signal so that the drive control circuit increases the current in the preheating stage to make the shape memory alloy wire reach the phase transition critical temperature, induces the shape memory alloy wire to produce shrinkage deformation in the triggering stage, and sustains the physical deformation in a low-power mode in the sustaining stage.

4. The driving and stepping feedback system for the shape memory wire motor of the insulin pump according to claim 1, characterized in that, The dynamic parameter sampling branch includes a sampling resistor and a filter capacitor connected in parallel with the sampling resistor; the microcontroller unit acquires the voltage and current data at both ends of the shape memory alloy wire through a built-in analog-to-digital converter, and calculates the real-time resistance value based on the ratio of voltage to current.

5. The drive and stepping feedback system for the shape memory wire motor of the insulin pump according to claim 4, characterized in that, The accuracy class of the sampling resistor is ±0.1%; the first feedback loop determines the percentage of physical deformation of the shape memory alloy wire by monitoring the slope and magnitude of the decrease in the real-time resistance value.

6. The drive and stepping feedback system for the shape memory wire motor of the insulin pump according to claim 1, characterized in that, The physical limit feedback component includes a miniature physical touch sensor; when the shape memory alloy ribbon drives the claw mechanism to complete one stepping action, the miniature physical touch sensor is pressed and generates the level transition signal.

7. The driving and stepping feedback system for the shape memory wire motor of the insulin pump according to claim 1, characterized in that, The adaptive logic control module has a preset time threshold of 500 milliseconds. If the adaptive logic control module detects that the resistance characteristic signal meets the preset contraction threshold, but does not receive the level transition signal within 500 milliseconds, it determines that the current state is a mechanism blockage or insufficient stroke.

8. The drive and stepping feedback system for the shape memory wire motor of the insulin pump according to claim 7, characterized in that, The adaptive logic control module includes error correction and compensation logic, which is used to increase the voltage, current, or power parameters of the drive control signal of the next drive sequence after determining that the travel is insufficient, with the increase being 3% of the current reference value.

9. The driving and stepping feedback system for the shape memory wire motor of the insulin pump according to claim 8, characterized in that, If the physical limit feedback component still fails to trigger the level transition signal after the system performs three consecutive compensation operations, the microcontroller unit stops driving the output and outputs a mechanical blockage error command to the external terminal.

10. The driving and stepping feedback system for the shape memory wire motor of the insulin pump according to claim 1, characterized in that, It also includes an ambient temperature sensor, and the microcontroller unit dynamically sets the reference value of the start drive control signal based on the ambient temperature data obtained by the ambient temperature sensor; the drive control circuit uses a gallium nitride power switch or a duct to control the temperature rise of the drive circuit itself to within 1 degree Celsius.

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