Automatic cardio-pulmonary resuscitation device and method

Abstract

The invention belongs to the technical field of medical first-aid equipment, and discloses an automatic cardio-pulmonary resuscitation device and method.Intelligent pressing control is achieved by integrating an outer sleeve, a driving assembly, a transmission assembly, a pressing assembly, a monitoring unit and a controller; the controller controls the driving assembly to drive the pressing assembly to move downwards according to the depth and dynamically adjusts the output torque of the driving assembly based on the estimated value of the contact force or the load torque, so that the contact force is stabilized in a preset near-zero force window, namely, the lower limit ensures that contact is not disengaged, and the upper limit limits the residual compression force. By adopting the device, the contradiction of the traditional device is effectively solved, the rebound resistance is eliminated to realize near-zero residual force, the smooth backflow of venous blood is ensured, meanwhile, the separation and re-collision of the pressing head and the chest wall are avoided, the rib fracture risk is reduced, and the equipment stability and the cardio-pulmonary resuscitation effect are improved.

Description

Technical Field

[0001] This invention belongs to the field of medical emergency equipment technology, and particularly relates to an automatic cardiopulmonary resuscitation device and method. Background Technology

[0002] Cardiac arrest is one of the leading causes of death worldwide. According to cardiopulmonary resuscitation guidelines, high-quality chest compressions not only need to meet the prescribed compression depth (50-60 mm) and compression rate (100-120 compressions / min), but also emphasize that the chest must be allowed to fully recoil between compressions. The negative pressure generated by the full recoil of the chest can effectively promote venous blood return to the heart, thereby ensuring cardiac output and coronary perfusion pressure at the next compression, buying time for further treatment of the patient and improving the success rate of resuscitation.

[0003] Currently, automated cardiopulmonary resuscitation (CPR) machines are widely used in the emergency treatment of cardiac arrest patients. However, they have significant technical deficiencies in achieving the crucial requirement of full chest recoil, which mainly manifests as a pair of irreconcilable contradictions. On the one hand, there is a dependency effect. Many traditional electric compression machines (such as crank-connecting rod type or devices using high reduction ratio gearboxes) cannot timely withdraw the force applied to the chest during the recoil phase due to the weight of the compression components themselves, the huge static friction of the transmission mechanism, or irreversible mechanical structures. This results in the compression head continuously compressing the chest, and even if the residual pressure is only a few kilograms, it will significantly increase intrathoracic pressure, hinder venous blood return, and greatly reduce the effectiveness of CPR. On the other hand, there is a risk of disengagement and re-impact. To eliminate the aforementioned leaning effect, some devices employ pneumatic or forced-lift designs for rapid forced retraction. However, when the retraction speed exceeds the natural rebound speed of the patient's chest, the compression head will separate from the chest wall, i.e., disengage. During the next compression cycle, the compression head, which is in an accelerated state, will violently impact the stationary or slowly moving chest wall. This high impact force can easily cause rib fractures in the patient and will also cause vibrations in the device's control system, affecting the device's operational stability.

[0004] It is evident that existing automated cardiopulmonary resuscitation (APR) machines cannot simultaneously address the leaning effect during the rebound phase and the risk of dislodgement and re-impact. They cannot achieve both eliminating rebound resistance to achieve near-zero residual force and avoid leaning, and closely following chest wall movements to avoid dislodgement and impact. Summary of the Invention

[0005] This invention provides an automatic cardiopulmonary resuscitation device and method. The device can solve the problem that existing automatic cardiopulmonary resuscitation machines cannot simultaneously solve the leaning effect and the risk of dislodgement-re-impact during the rebound phase. It can both eliminate rebound resistance to achieve near-zero residual force and avoid leaning, and closely follow the chest wall to follow the movement of the rib cage to avoid dislodgement and impact.

[0006] To achieve the above objectives, the present invention employs the following technical content: An automated cardiopulmonary resuscitation device includes: an outer sleeve; A drive assembly is provided on one side of the outer sleeve, and a transmission assembly is connected to the output end of the drive assembly. The outer sleeve has a cavity, and a pressing component capable of pressing along the pressing axis is inserted into the cavity; The transmission component is connected to the pressing component via a reversible drive mechanism; The monitoring unit is used to collect the compression depth of the compression component and the contact force between the compression component and the patient's chest. The controller, connected to both the drive assembly and the monitoring unit, controls the drive assembly to move the compression assembly downwards based on the compression depth collected by the monitoring unit; and controls the output torque of the drive assembly based on the estimated contact force or load torque collected by the monitoring unit, so that the contact force between the compression assembly and the patient's chest remains within a preset near-zero force window, enabling the compression assembly to actively follow the chest recoil; wherein, the near-zero force window is defined as the contact force... ;in, A force threshold greater than or equal to zero is used to ensure that the compression component remains in contact with the chest cavity and does not slip out; The upper limit threshold of the force is less than the preset pressure value, which is used to limit the residual pressure force of the compression component on the chest.

[0007] Furthermore, the drive assembly includes a servo motor fixed to one side of the outer sleeve; The transmission assembly includes a synchronous belt, a first synchronous pulley, and a second synchronous pulley; The first synchronous pulley is connected to the second synchronous pulley via a synchronous belt; The output shaft of the servo motor is connected to the first synchronous pulley; The second synchronous pulley is connected to the reversible drive mechanism.

[0008] Furthermore, the reversible drive mechanism includes a ball screw; The pressing assembly includes a connected inner sleeve and a pressing head; One end of the ball screw is connected to the second synchronous pulley, and the other end is connected to the inner sleeve through the screw nut; The inner sleeve and the pressing head can move along the pressing axis within the cavity of the outer sleeve.

[0009] Furthermore, a gravity compensation component is also provided inside the outer sleeve cavity to counteract the gravity of the pressing component and the reversible drive transmission mechanism; The gravity compensation component includes a spring; the spring is coaxially sleeved on the ball screw; one end of the spring is fixed to the top or middle fixing ring of the outer sleeve, and the other end is fixed to the inner sleeve, used to provide an upward elastic force in the event of power failure or when the servo motor has no torque output, so that the pressing component can automatically retract to the upper stop point or remain in a hovering state; the elastic force satisfy:

[0010] In the formula, The total weight of the pressing component and the reversible drive mechanism; This is the equivalent static friction force of the system when it is stationary or at low speed.

[0011] Furthermore, the monitoring unit includes a position sensor and a force sensor; The position sensor is connected to the outer sleeve; The outer wall of the inner sleeve is provided with protrusions. When the inner sleeve is displaced along the pressing axis, the protrusions come into contact with the position sensor so that the position sensor can collect the pressing depth of the pressing component. The force sensor is located at the connection between the inner sleeve and the pressing head or integrated inside the pressing head, and can collect the contact force between the pressing component and the patient's chest. The monitoring unit also includes travel limit and safety detection elements.

[0012] Furthermore, the travel limit and safety detection elements are located near the upper and lower dead points of the inner sleeve, including limit switches, proximity switches, or Hall sensors, to detect whether the pressing component has reached the safe travel boundary, and to issue an alarm or stop the drive in abnormal situations.

[0013] A control method for an automated cardiopulmonary resuscitation (CPR) device, based on the aforementioned automated CPR device, includes: S1: Press Downward Control: The controller controls the drive component to drive the pressing component downward along a preset speed trajectory, using a position or speed closed-loop control mode, until the target pressing depth is reached; S2: Phase switching detection: Real-time monitoring of changes in pressing depth and / or contact force. When the lower stop point is reached or the phase switching condition is met, the system switches to the rebound follow control mode. S3: Rebound Follow-up Control: The controller adopts force closed-loop control, impedance control or admittance control strategies; S4: Real-time adjustment: In step S3, the actual contact force between the compression component and the chest is obtained in real time. Or equivalent load torque; S5: The controller adjusts the torque of the drive assembly based on the actual contact force. like Greater than the upper limit of the near-zero force window The control drive components increase the upward auxiliary torque to eliminate the reliance on the thorax; like Less than the lower limit of the near-zero force window The control drive components reduce the upward torque or apply a downward following torque to track the thoracic rebound and prevent slippage. S6: Cycle determination: When the pressing component rebounds with the chest cavity to the upper stop point or reaches the preset rebound time, proceed to step S1 of the next cycle.

[0014] Further, in step S3, the output torque command of the drive component... Including friction feedforward compensation and force feedback adjustment terms, the specific control law formula is as follows:

[0015] In the formula, Based on the current rebound speed The system dynamic friction feedforward compensation is used to counteract the dynamic friction resistance of the mechanical transmission system. For gravity compensation residuals, it is used to compensate for the trace amounts of gravity that are not completely offset by the gravity compensation components; , These are the proportional and differential gains for force control, respectively; The target contact force is set within a near-zero force window; This is the measured contact force.

[0016] Furthermore, the control method further includes: The specific steps for friction model identification and correction are as follows: During the device's power-on self-test or idle phase, the pressing component is driven to run under no-load, and the current value of the servo motor at different speeds is recorded to construct a speed-friction torque curve. The drive component uses a servo motor. During actual pressing, the friction feedforward compensation is updated online based on the integral or mean of the force error. The parameters are adjusted to accommodate the drift in frictional characteristics caused by device wear or temperature changes.

[0017] Furthermore, the control method further includes: The specific steps of the thoracic wall compliance adaptation process are as follows: During the compression process in step S1, force-displacement data is recorded, and the current chest stiffness coefficient of the patient is calculated based on the force-displacement data. Based on the thoracic stiffness coefficient, the control parameters of the rebound following control in step S3 are adaptively adjusted to improve the sensitivity of the device's following response.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention provides an automated cardiopulmonary resuscitation (CPR) device that integrates an outer sleeve, a drive assembly, a transmission assembly, a compression assembly, a monitoring unit, and a controller to achieve intelligent compression control. The monitoring unit collects compression depth and the contact force between the compression assembly and the chest wall in real time. The controller controls the drive assembly to move the compression assembly downwards based on the compression depth and dynamically adjusts the output torque of the drive assembly based on the estimated contact force or load torque, stabilizing the contact force within a preset near-zero force window. This means the lower limit ensures contact is not lost and the upper limit restricts residual pressure. In this device, the controller actively follows the chest wall during the rebound phase through torque adjustment: when the contact force approaches the upper limit, the output torque is reduced to alleviate pressure and prevent leaning; when it approaches the lower limit, the torque is increased to maintain a light touch and prevent loss of contact, thus precisely matching the natural rebound speed of the chest wall. This device effectively solves the contradictions of traditional devices, eliminating rebound resistance to achieve near-zero residual force, ensuring smooth venous blood return, and preventing separation of the compression head from the chest wall and re-impact, reducing the risk of rib fractures and improving device stability and CPR effectiveness.

[0019] This invention also provides a control method for an automated cardiopulmonary resuscitation (CPR) device. Based on the aforementioned CPR device, the compression assembly is first driven downward along a preset trajectory to the target depth using position or velocity closed-loop control. Upon detecting the lower stop point or phase switching condition, it immediately switches to force closed-loop, impedance, or admittance control mode. By monitoring the contact force or equivalent load torque in real time, the output torque of the drive assembly is dynamically adjusted—when the contact force exceeds the upper limit of the near-zero window, an upward auxiliary torque is increased to eliminate leaning pressure; when it falls below the lower limit, the upward torque is reduced or a downward following torque is applied to track chest movement and prevent dislodgement, until the chest rebounds to the upper stop point, at which point the next cycle is restarted. In this method, dynamic balance is constructed using real-time force feedback: through active bidirectional adjustment of torque (upward unloading / downward compliant following), the compression head always conforms to the natural rebound trajectory of the chest with near-zero residual force. This method avoids the shortcomings of traditional devices, eliminating residual pressure during the rebound phase to ensure venous return, and avoiding the risk of dislodgement and re-impact through dynamic following, significantly reducing the probability of rib fractures and improving device stability and resuscitation effectiveness. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall appearance of an automatic cardiopulmonary resuscitation device provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of an automated cardiopulmonary resuscitation device provided in an embodiment of the present invention; Figure 3 This is a schematic cross-sectional view of an automated cardiopulmonary resuscitation device provided in an embodiment of the present invention; Figure 4A control principle block diagram of an automatic cardiopulmonary resuscitation device provided in an embodiment of the present invention; Figure 5 The timing waveform diagram of position, contact force and motor torque for a single pressing cycle is provided for an embodiment of the present invention; Figure 6 This is a schematic diagram of the anti-loosening and anti-leaning state machine logic based on the contact force window during the rebound stage, provided in an embodiment of the present invention.

[0021] Figure label: 1. Servo motor; 2. Fixing plate; 3. Synchronous belt; 4. First synchronous pulley; 5. Second synchronous pulley; 6. Bushing; 7. Bearing; 8. Outer sleeve; 9. Spring; 10. Ball screw; 11. Inner sleeve; 12. Pressing head; 13. Limit block; 14. Inner liner; 15. Position sensor. Detailed Implementation

[0022] To make the technical problems solved by the present invention, the technical solutions, and the beneficial effects clearer, the following specific embodiments provide a further detailed description of the present invention. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.

[0023] 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, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] As mentioned in the background section, existing automated cardiopulmonary resuscitation (APR) machines have significant technical deficiencies in achieving "full rebound," mainly manifested in a contradiction: (1) "Resistance" effect: Many traditional electric chest compression machines (such as crank-connecting rod type or devices using high reduction ratio gearboxes) cannot withdraw force in time during the rebound phase due to the weight of the compression components themselves, the huge static friction of the transmission mechanism, or irreversible mechanical structures (such as trapezoidal lead screws), resulting in the compression head continuously compressing the chest cavity. This residual pressure (even if it is only a few kilograms) will significantly increase intrathoracic pressure, hinder venous return, and reduce the resuscitation effect.

[0027] (2) Risk of “Vacuum-Re-impact”: To eliminate leaning, some devices (such as pneumatic or forced-lift types) employ a rapid, forced retraction method. If the retraction speed exceeds the natural rebound speed of the patient's chest (especially for elderly patients or those with poor chest compliance), the compression head will separate from the chest wall (vacuum). During the next cycle, the accelerating compression head will violently impact the stationary or slowly moving chest wall. This high impact force can easily cause rib fractures and oscillations in the control system.

[0028] To solve the above problems, such as Figure 1 As shown, this embodiment provides an automatic cardiopulmonary resuscitation device. This device can eliminate rebound resistance to achieve near-zero residual force, without leaning, and can closely follow the chest wall to avoid dislodgement and impact.

[0029] For example, this embodiment provides an automatic cardiopulmonary resuscitation device, including: an outer sleeve 8; a drive assembly is disposed on one side of the outer sleeve 8, and a transmission assembly is connected to the output end of the drive assembly; a cavity is opened inside the outer sleeve 8, and a compression assembly capable of moving along the compression axis is inserted in the cavity; the transmission assembly is connected to the compression assembly through a reversible drive transmission mechanism; it also includes a monitoring unit for collecting the compression depth of the compression assembly and the contact force between the compression assembly and the patient's chest; a controller, connected to the drive assembly and the monitoring unit respectively, for controlling the drive assembly to drive the compression assembly downward according to the compression depth collected by the monitoring unit; and controlling the output torque of the drive assembly according to the contact force or load torque estimated value collected by the monitoring unit, so that the contact force between the compression assembly and the patient's chest is maintained within a preset near-zero force window, realizing the active following of the chest rebound of the compression assembly; wherein, the near-zero force window is defined as the contact force F∈ ;in, A force threshold greater than or equal to zero is used to ensure that the compression component remains in contact with the chest cavity and does not slip out; The upper limit threshold of the force is less than the preset pressure value, which is used to limit the residual pressure force of the compression component on the chest.

[0030] The testing machine provided in this embodiment will be further described in detail below with reference to the accompanying drawings: like Figure 2 and Figure 3As shown, this embodiment provides an automated cardiopulmonary resuscitation (CPR) device, including a frame assembly, a compression assembly, a drive assembly, a reversible drive mechanism, a monitoring unit, a controller, and a gravity compensation assembly. All components are integrated and arranged along the compression axis (Z-axis) to form a linear reciprocating compression actuator with high reversible drive characteristics and passive gravity compensation capability; the specific structure is as follows: 1. Rack assembly: The rack assembly includes an outer sleeve 8, preferably an integral frame or box-type structure, wherein: The outer sleeve 8 is a hollow cylindrical or polygonal cylindrical structure, used to provide coaxial support and guiding reference for the internal reversible drive transmission mechanism and pressing assembly. The axis of the outer sleeve 8 is the pressing axis Z-axis, and through rigid connection with the upper motor fixing plate 2 and the lower support structure, it forms an overall stable mechanical frame.

[0031] The fixing plate 2 is fixedly installed on the upper end or above the outer sleeve 8, and is used to install the servo motor 1, the second synchronous pulley 5, and the support components at the upper end of the ball screw 10. The fixing plate 2 is preferably made of aluminum alloy or steel plate to ensure sufficient rigidity and dimensional accuracy.

[0032] Bearing housing and support structure: A bearing housing is provided at the top or middle of the outer sleeve 8, and the bearing 7 provides radial and axial support to the ball screw 10, ensuring that the screw has good coaxiality and low vibration characteristics during high-speed reciprocating motion.

[0033] The frame assembly 8 serves as the mounting base, rigid support, and guide housing, enabling the linear drive assembly and the pressing assembly to move along the Z-axis while ensuring high precision.

[0034] 2. Press component: The pressing assembly mainly includes an inner sleeve 11 and a pressing head 12, and is connected to a reversible drive mechanism (preferably a ball screw 10) via a screw nut to achieve precise reciprocating motion along the Z-axis.

[0035] The inner sleeve 11 is a hollow sleeve-shaped component, with its outer surface mating with the inner liner 14. A lead screw nut is fixed inside the cavity. The lead screw nut and the ball screw 10 form a rolling pair, converting the rotational motion generated by the motor drive into the linear motion of the pressing assembly. The lower end of the inner sleeve 11 is rigidly or semi-rigidly connected to the pressing head 12, and its external dimensions correspond to those of the outer sleeve 8 and the inner liner 14 to provide sufficient guiding accuracy and smooth movement during reciprocating motion.

[0036] The compression head 12 is located at the lower end of the inner sleeve 11 and is the working end that directly contacts the patient's sternum / thoracic cage. The compression head 12 can be designed as a disc, an arc surface, or a non-planar structure that conforms to the anatomical curvature of the sternum. Its contact surface is preferably covered with a flexible cushioning material to disperse local stress and reduce the risk of rib fracture.

[0037] Force sensors, such as strain gauge sensors or piezoelectric sensors, can be integrated inside the pressing head 12 or at the connection with the inner sleeve 11 to measure the contact force between the pressing head and the chest cavity in real time during the pressing process, providing basic data for near-zero force control during the rebound phase.

[0038] It also includes guiding and anti-rotation mechanisms: To prevent the inner sleeve 11 from losing its pure linear motion characteristics due to rotation with the ball screw 10, a guide anti-rotation structure is provided between the outer sleeve 8 and the inner sleeve 11. The implementation method can be as follows: The first method uses an inner liner 14 as a radial guide, while a longitudinal keyway is provided on the outer circumference of the inner sleeve 11 to cooperate with the inner key or slider on the outer sleeve 8; or The second method involves adding a longitudinal guide strip to the outer wall of the inner sleeve 11, which fits into the guide groove on the inner wall of the outer sleeve 8.

[0039] The above method ensures that the inner sleeve 11 does not rotate during linear reciprocating motion in the Z-axis direction, thus improving the stability of the pressing motion.

[0040] For example, the end of the outer sleeve 8 is also provided with a limiting mechanism, specifically: a limiting block 13 or a limiting ring is provided at both ends of the movement stroke of the inner sleeve 11. When the inner sleeve 11 approaches the design stroke boundary, it contacts the corresponding limiting structure to prevent the pressing head 12 from exceeding the safe stroke range and avoid excessive pressure on the patient's chest or mechanical damage to the device body.

[0041] The limit mechanism can also be linked with a travel switch or proximity sensor to send an alarm signal to the controller when there is a tendency for the travel to exceed the limit, thus achieving dual mechanical and electrical safety protection.

[0042] 3. Drive assembly and reversible drive transmission mechanism: The drive assembly includes a servo motor 1; the drive assembly is connected to the reversible drive transmission mechanism through a conventional assembly; the conventional assembly adopts a synchronous belt drive mechanism; the reversible drive transmission mechanism adopts a ball screw 10; together they form a power transmission chain of "motor - pulley - screw - screw nut - pressing assembly".

[0043] For example, the servo motor 1 is fixed to the lower side of the mounting plate 2 via a mounting flange, and its output shaft is rigidly connected to the first synchronous pulley 4. A low cogging torque, high bandwidth servo motor is preferably used to reduce speed fluctuations and improve the resolution of small torque adjustments, ensuring good controllability and dynamic performance during the force control phase from a hardware perspective.

[0044] The first synchronous pulley 4 on the motor output shaft is connected to the second synchronous pulley 5 via the synchronous belt 3, completing the first-stage reduction or constant speed transmission from the motor output end to the ball screw 10.

[0045] In this embodiment, the synchronous belt transmission ratio is preferably between 1:1 and 3:1, more preferably a low reduction ratio range of 1:1 to 2:1. This range can significantly reduce frictional losses and rigid self-locking effects in the transmission chain while ensuring that the pressing stroke and speed meet CPR specifications. The synchronous belt 3 can adopt a steel wire rope core or a high-strength fiber reinforced structure to reduce the degradation of transmission stiffness and backlash.

[0046] Compared with the traditional structure that uses multi-stage planetary reducers or worm gear reducers, this embodiment greatly improves the energy return efficiency during axial reverse drive by using a single-stage synchronous belt low reduction or constant speed transmission. This allows the force applied to the pressing head 12 by the thoracic cavity during rebound to be more directly "pushed back" to the motor rotor, achieving high reverse drive motion.

[0047] The specific design of the reversible drive mechanism is as follows: In this embodiment, the reversible drive mechanism preferably uses a ball screw 10. The upper end of the ball screw 10 is mounted via a bearing 7 and supported by a bushing 6 or a bearing seat, and its upper end is rigidly connected to the second synchronous pulley 5. The lead of the ball screw 10 is designed to be 8mm to 20mm, preferably a large lead range of 10mm to 16mm.

[0048] The technical effects brought about by the large lead design adopted in this embodiment include: First, the number of motor rotations required per unit linear stroke is reduced, thereby lowering the reduction ratio requirement and the total friction in the transmission system; Second, when the chest rebounds upward and drives the pressing component upward, the reverse driving force corresponding to the linear motion can be efficiently converted into the screw rotation torque through the low-friction ball joint, and reverse-drive the motor rotor to rotate, thus achieving high reverse drive characteristics. Third, compared with trapezoidal lead screws or small lead ball screws, large lead ball screws without self-locking structure have almost no self-locking capability. When the servo motor 1 outputs extremely low torque or no torque during the rebound phase, the pressing component can freely retract under the drive of external force chest rebound and spring 9 tension.

[0049] The lead screw nut is installed inside the inner sleeve 11 and is fixed in the inner cavity of the inner sleeve 11 by threads, pins, or pressure plates to ensure that it does not shift or rotate under Z-axis force. The lead screw nut and the ball screw 10 are in rolling contact, which has a low coefficient of friction and low backlash, which is beneficial for precise control of the pressing depth and sensitive response to the reverse driving force when the chest rebounds.

[0050] To further reduce friction and noise, a preloaded ball nut structure can be selected. The ball filler preload eliminates backlash, making the transmission smoother and without obvious dead zones.

[0051] The drive assembly in this embodiment avoids using self-locking or high-friction components, such as worm gears, self-locking trapezoidal screws, and rack and pinion high-speed reduction gearboxes. Instead, it achieves the following effects through a simple two-stage transmission of "low-speed synchronous belt + large-lead ball screw": During the downward pressing phase: the motor is in an active driving state, and the output torque is transmitted to the pressing head 12 through a low-friction transmission chain, so as to achieve precise control of pressing depth and speed; During the natural rebound phase of the thoracic cavity: the pressing head 12 is driven by the upward force of the thoracic cavity and the tension of the spring 9, which drives the inner sleeve 11 to move upward, thereby driving the lead screw nut, ball screw 10 and motor rotor to rotate in the opposite direction; since there is no obvious self-locking element in the transmission chain, the reverse driving resistance is extremely small, and the motor only needs to output a small compensation torque to achieve near-zero residual force following under the control algorithm.

[0052] This creates the physical conditions for subsequent force / resistance control with "low damping and high transparency" at the mechanical level, fundamentally weakening the formation mechanism of the dependency effect.

[0053] 4. Guiding and friction control structure: To further ensure smooth movement and reduce friction, this embodiment includes an inner liner 14 and related mating structures between the pressing assembly and the frame assembly. The inner liner 14 is disposed between the outer sleeve 8 and the inner sleeve 11, and can be made of self-lubricating materials such as POM, PTFE, or engineering plastics with added lubricating fillers. The inner and outer surfaces of the inner liner 14 form a sliding fit or a micro-clear gap fit with the inner sleeve 11 and the outer sleeve 8, respectively.

[0054] By optimizing the fit tolerances and surface roughness, the frictional resistance of the inner sleeve 11 during Z-axis movement is significantly reduced, while maintaining sufficient guiding stiffness to prevent significant swaying or deflection. This structural design directly reduces the static friction (f_static) and dynamic friction of the system, which helps the spring 9 to balance the weight of the component with a smaller elastic force.

[0055] Regarding friction and clearance control: During the design and assembly process, by selecting high-precision bearings 7, precision ball screws 10, and low-friction inner liners 14, the equivalent frictional torque in the overall transmission chain is kept within a predictable and compensable range. Combined with friction feedforward compensation in the subsequent control algorithm, the overall system performance can be adjusted to an approximately "frictionless" state, thereby achieving extremely high mechanical transparency and following sensitivity during the rebound phase.

[0056] 5. Gravity compensation components and their arrangement: The gravity compensation component is used to physically counteract the weight of the pressing component and some of the transmission components, thereby preventing the pressing component from exerting additional pressure on the chest due to its own weight during the rebound phase.

[0057] like Figure 3 As shown, the gravity compensation component is preferably a long-stroke pre-tensioned spring 9. The spring 9 is coaxially sleeved outside the ball screw 10 and the inner sleeve 11, located in the annular cavity (i.e., the cavity of the outer sleeve 8) formed between the outer sleeve 8 and the inner sleeve 11.

[0058] One end of the spring 9 is fixed to the top or middle fixing ring of the outer sleeve 8, and the other end is fixed to the inner sleeve 11 through a connecting ring or hook structure, so that the length of the spring changes accordingly when the pressing assembly moves up and down along the Z-axis, thereby providing an upward elastic force.

[0059] For example, the spring stiffness k and preload x0 are specifically calculated and experimentally calibrated so that within the effective CPR pressing stroke range, such as 0-60mm, the upward pulling force applied by spring 9 to the pressing assembly is... Always satisfy:

[0060] in: The total weight of the pressing assembly, including the inner sleeve 11, pressing head 12, lead screw nut, and some connecting parts, is [to be specified]. This is the equivalent static friction force of the system when it is stationary or at low speed.

[0061] The above design ensures that when the motor is powered off or the output torque is zero, the upward elastic force provided by the spring 9 is sufficient to overcome the weight of the pressing assembly and the main static friction force, so that the pressing head 12 has a natural tendency to float up or remain suspended, without exerting additional pressure on the patient's chest due to gravity.

[0062] Safe operating status: Under normal operating conditions, servo motor 1 only needs to output a small amount of fine-tuning torque during the rebound phase to compensate for the nonlinear residual of spring 9, dynamic friction, and system inertia. In the event of a power outage, control system failure, or emergency stop, the servo motor stops working, but spring 9 continues to provide upward pulling force, automatically raising the pressing component to the upper dead center or near the upper dead center position. This prevents the weight of the device from continuously acting on the patient's chest, improving the system's safety and fault robustness.

[0063] 6. Design of the monitoring unit: The monitoring unit includes a position sensor 15, a force sensor, and a travel limit and safety detection element, wherein: The position sensor 15 is used to monitor the absolute position of the pressing component relative to the frame, i.e., the pressing depth, in real time. In this embodiment, the position sensor 15 adopts a split installation structure, taking a wire encoder or linear displacement sensor as an example: the outer wall of the inner sleeve 11 is provided with protrusions. When the inner sleeve 11 is displaced along the pressing axis, the protrusions make contact with the position sensor 15 to press, so that the position sensor 15 can collect the pressing depth of the pressing component.

[0064] Fixed end body: Rigidly mounted on the lower surface of the fixed plate 2 or the outer wall of the outer sleeve 8. As shown in the figure, the sensor body is located next to the servo motor 1 and remains relatively stationary with the frame assembly, not moving with the pressing head.

[0065] The moving end measuring rod or pull wire extends downward parallel to the Z-axis and is rigidly connected to the upper end face or side wall of the inner sleeve 11.

[0066] Working principle: When the servo motor 1 drives the inner sleeve 11 to press down or rebound upward along the Z-axis, the inner sleeve 11 causes the moving end of the sensor to displace relative to the fixed end, and the sensor outputs a real-time electrical signal corresponding to the pressing depth. This installation method ensures that the sensor can directly measure the actual displacement of the inner sleeve 11, i.e., the pressing head 12, relative to the stationary frame, avoiding measurement errors caused by transmission gaps.

[0067] In this embodiment, the force sensor can be arranged at the connection between the compression head 12 and the inner sleeve 11, or directly integrated into the internal structure of the compression head 12. Its output signal represents the instantaneous contact force between the compression head and the patient's chest, providing basic data for force control and impedance control during the rebound phase.

[0068] In mechanical design, the following can be adopted: The first method involves attaching thin-film strain gauges to a metallic elastomer to form a force sensing unit for stress signals in response to minute displacements. The second type is a piezoelectric force sensing element, which measures changes in pressure.

[0069] Meanwhile, the sensing element is protected by a protective housing and a sealing structure to prevent it from being corroded by contaminated liquids or cleaning agents in clinical use environments.

[0070] In this embodiment, the travel limit and safety detection elements are specifically arranged as follows: The travel limit and safety detection elements can be limit switches, proximity switches or Hall sensors, which are installed near the upper and lower dead points of the inner sleeve 11 to detect whether the pressing component has reached the safe travel boundary and to issue an alarm or stop the drive in abnormal situations.

[0071] 7. Controller: The controller is connected to both the drive assembly and the monitoring unit. It controls the drive assembly to move the compression assembly downwards based on the compression depth collected by the monitoring unit. It also controls the output torque of the drive assembly based on the estimated contact force or load torque collected by the monitoring unit, ensuring that the contact force between the compression assembly and the patient's chest remains within a preset near-zero force window, allowing the compression assembly to actively follow the chest's rebound. The near-zero force window is defined as the contact force... ;in, A force threshold greater than or equal to zero is used to ensure that the compression component remains in contact with the chest cavity and does not slip out; The upper limit threshold of the force is less than the preset pressure value, which is used to limit the residual pressure force of the compression component on the chest.

[0072] Therefore, this embodiment provides an automated cardiopulmonary resuscitation device. Through the above-described mechanical structure design and arrangement, the device achieves the following key technical effects at the hardware level, providing a foundation for the implementation of subsequent control strategies: First, high reverse drive capability and low friction transmission chain: The combination of synchronous belt low reduction ratio transmission and large lead ball screw makes the transmission system almost free of self-locking characteristics when moving in the axial direction. The upward lifting force of the chest cavity rebound can easily reverse and drive the pressing component and motor rotor to rotate. At the same time, the use of self-lubricating inner liner 14 and precision bearing 7 further reduces static and dynamic friction, laying the foundation for "mechanical transparency" from a mechanical construction perspective.

[0073] Second, passive gravity compensation and failure safety: The long-stroke pre-tensioned spring 9 provides physical gravity compensation by offering an upward pulling force greater than or equal to the weight of the pressing assembly throughout the entire pressing stroke. Even in the event of control system or motor failure, the pressing head 12 will not exert continuous pressure on the patient's chest due to the device's own weight, but will tend to float upward or retract, improving the device's safety and reliability under extreme conditions.

[0074] Third, high-precision guidance and anti-rotation design: Under the constraint of the outer sleeve 8 and the inner liner 14, the inner sleeve 11 makes a single-degree-of-freedom linear motion along the Z-axis. With the necessary anti-rotation keyway or guide bar structure, it avoids positional displacement and torsional vibration caused by rotation, ensuring that the pressing head 12 is always facing the sternum in a preset posture, reducing the risk of displacement pressing.

[0075] Fourth, creating physical conditions for near-zero residual force control: Since the influence of gravity of the mechanical system itself is offset by spring 9, the friction force is reduced to a compensable range through structural optimization, and high reverse drive is achieved through ball screw and synchronous belt. The control system only needs a small motor torque adjustment during the rebound phase to keep the pressing head 12 within a near-zero residual force window of 0-5N during the chest cavity rebound process, achieving the ideal following state of "neither leaning on nor falling off".

[0076] It should be further noted that although this embodiment describes in detail the use of a "servo motor + synchronous belt + ball screw" as the drive component, this is only a preferred embodiment of the present invention. Those skilled in the art should understand that any drive mechanism with controllable drive capability and allowing reverse transmission can be applied to this invention. For example, in another embodiment, the drive component can be replaced with a linear motor or voice coil motor to directly drive the pressing component to reciprocate, without the need for an intermediate rotary-linear conversion mechanism. Linear motors naturally possess low friction and high response characteristics, and can also be used in conjunction with the control algorithm of this invention to achieve a "near-zero force following" effect; therefore, both fall within the protection scope of this invention.

[0077] Furthermore, in this embodiment, the gravity compensation component not only reduces the motor load but also provides a power failure safety function. When the device experiences an unexpected power outage or malfunction, the motor loses its self-locking torque. Under the pulling force of the gravity compensation component (such as a spring), the pressing component automatically retracts to the upper frame, thereby immediately relieving pressure on the patient's chest and ensuring medical safety.

[0078] Based on the above-mentioned automated cardiopulmonary resuscitation (CPR) device, this embodiment also provides a control method for the automated CPR device, the specific steps of which are as follows: S1: Press Downward Control: The controller controls the drive component to drive the pressing component downward along a preset speed trajectory, using a position or speed closed-loop control mode, until the target pressing depth is reached; S2: Phase switching detection: Real-time monitoring of changes in pressing depth and / or contact force. When the lower stop point is reached or the phase switching condition is met, the system switches to the rebound follow control mode. S3: Rebound Follow-up Control: The controller adopts force closed-loop control, impedance control or admittance control strategies; S4: Real-time adjustment: In step S3, the actual contact force between the compression component and the chest is obtained in real time. Or equivalent load torque; S5: The controller adjusts the torque of the drive assembly based on the actual contact force. like Greater than the upper limit of the near-zero force window The control drive components increase the upward auxiliary torque to eliminate the reliance on the thorax; like Less than the lower limit of the near-zero force window The control drive components reduce the upward torque or apply a downward following torque to track the thoracic rebound and prevent slippage. S6: Cycle determination: When the pressing component rebounds with the chest cavity to the upper stop point or reaches the preset rebound time, proceed to step S1 of the next cycle.

[0079] Among them, the output torque command of the drive component Including friction feedforward compensation and force feedback adjustment terms, the specific control law formula is as follows:

[0080] In the formula, Based on the current rebound speed The system dynamic friction feedforward compensation is used to counteract the dynamic friction resistance of the mechanical transmission system. For gravity compensation residuals, it is used to compensate for the trace amounts of gravity that are not completely offset by the gravity compensation components; , These are the proportional and differential gains for force control, respectively; The target contact force is set within a near-zero force window; This is the measured contact force.

[0081] The specific steps for friction model identification and correction are as follows: During the device's power-on self-test or idle phase, the pressing component is driven to run under no-load conditions, and the current value of servo motor 1 at different speeds is recorded to construct a speed-friction torque curve. The drive component is a servo motor 1. During actual pressing, the friction feedforward compensation is updated online based on the integral or mean of the force error. The parameters are adjusted to accommodate the drift in frictional characteristics caused by device wear or temperature changes.

[0082] In addition, this control method also includes a thoracic compliance adaptive process, the specific steps of which are as follows: During the compression process in step S1, force-displacement data is recorded, and the current chest stiffness coefficient of the patient is calculated based on the force-displacement data. Based on the thoracic stiffness coefficient, the control parameters of the rebound following control in step S3 are adaptively adjusted to improve the sensitivity of the device's following response.

[0083] Combination Figures 4 to 6 The dual-loop switching and force / impedance control strategy in the control method provided in this embodiment will be described in detail below: The controller executes the following control loop: 1. The downward pressure phase is dominated by position: like Figure 5 As shown, in At the bottom dead center, the controller operates a high-bandwidth position / velocity closed-loop PID control. The input is a pre-planned S-shaped velocity curve trajectory, driving servo motor 1 to rotate, which in turn drives the inner sleeve 11 to descend rapidly. The goal at this stage is to accurately reach a depth of 50-60mm, with smooth acceleration at the moment of bottoming out to reduce impact on the sternum.

[0084] 2. Lower dead center switching: When the position sensor 15 detects that the set depth has been reached, and the force sensor detects that the reaction force has reached its peak and begins to decrease, or when the motor current shows a reverse trend, the controller triggers a phase switch, disconnects the position loop, and connects the rebound following control loop.

[0085] 3. Force / resistance dominance during the upward rebound phase: At this point, the control objective is no longer "returning to the position Z=0", but "maintaining contact force". ".

[0086] like Figure 6 As shown, the controller executes the following control law:

[0087] Dynamic friction feedforward: Based on the friction model identified by the system, and according to the current rebound speed... A torque is pre-output to counteract the resistance of the transmission system. This makes the system exhibit extremely low damping characteristics, as if there were no friction.

[0088] Force feedback: Set it to 2N within the 0-5N window.

[0089] Detailed explanation of the logic: Anti-leaning scenario: If the patient's chest recoils slowly or stops recoiling, and the compression head attempts to press against the chest wall due to inertia, the sensor detects... .at this time When the value is negative, the motor outputs a reverse upward torque, actively lifting the pressing head until the force returns to 2N.

[0090] Anti-dislodgement scenario: If the patient's chest recoils extremely quickly, such as in a young patient, and the chest wall tends to detach from the compression head, the sensor detects... Or close to 0. At this point When the value is positive, the motor outputs a positive downward torque, accelerating the downward movement of the pressing head to "catch up" with the chest wall until contact is maintained.

[0091] 4. System Identification and Adaptation: This device automatically performs a full no-load run during each power-on self-test. The controller records the motor current at different speeds, fits the system's inherent Coulomb and viscous friction coefficients, and generates... The curve. In actual treatment, the controller will also fine-tune the parameters of this curve online based on the long-term integral value of the force error to adapt to the drift of frictional characteristics caused by temperature changes or mechanical wear, ensuring the accuracy of control.

[0092] Through the deep integration of the above-mentioned mechanical structure and control algorithm, the present invention achieves the effect of the compression head "floating" on the chest wall during the rebound phase, perfectly solving the long-standing contradiction between "leaning" and "loosening" in cardiopulmonary resuscitation.

[0093] The control method provided in this embodiment also includes an adaptive friction learning process, as detailed below: The device performs a "system identification" during each power-on self-test or idle period. It drives the pressing head 12 under no-load conditions, records the current values ​​at different speeds, and fits the inherent friction curves of the transmission system bearing 7, ball screw 10, and inner liner 14. In actual pressing, this curve acts as a feedforward term, greatly reducing the burden on the PID feedback loop and improving the system's response speed and transparency.

[0094] Through the deep integration of the above-mentioned mechanical structure and control algorithm, the present invention achieves the effect of the compression head "floating" on the chest wall during the rebound phase, perfectly solving the long-standing contradiction between "leaning" and "loosening" in cardiopulmonary resuscitation.

[0095] In summary, the present invention provides an automated cardiopulmonary resuscitation device and method, which has the following advantages compared with existing automated cardiopulmonary resuscitation devices: First, near-zero residual force following: the combination of physical gravity compensation and algorithmic friction compensation completely eliminates the "leaning" phenomenon and ensures venous return.

[0096] Secondly, it provides safety and impact protection: by maintaining a weak positive contact force through closed-loop force control, it eliminates the phenomenon of slippage and avoids secondary impacts that could damage the patient's bones.

[0097] Third, high safety and robustness: even if the electronic system fails, the passive compensation of the mechanical spring can prevent the pressure head from pressing on the patient; the high reverse drive design allows medical staff to take over manually in an emergency.

[0098] Fourth, intelligent adaptive: It can automatically adjust the following strategy according to the different patients' chest wall stiffness, and has a wide range of applications.

[0099] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. An automatic cardiopulmonary resuscitation device, characterized in that, include: Outerwear (8); A drive assembly is provided on one side of the outer sleeve (8), and the output end of the drive assembly is connected to a transmission assembly; The outer sleeve (8) has a cavity, and a pressing component that can press along the pressing axis is inserted in the cavity; The transmission component is connected to the pressing component via a reversible drive mechanism; The monitoring unit is used to collect the compression depth of the compression component and the contact force between the compression component and the patient's chest. The controller is connected to the drive component and the monitoring unit respectively, and is used to control the drive component to drive the pressing component downward according to the pressing depth collected by the monitoring unit; The output torque of the drive component is controlled based on the estimated contact force or load torque collected by the monitoring unit, so that the contact force between the compression component and the patient's chest remains within a preset near-zero force window, enabling the compression component to actively follow the chest recoil; wherein, the near-zero force window is defined as the contact force... ;in, A force threshold greater than or equal to zero is used to ensure that the compression component remains in contact with the chest cavity and does not slip out; The upper limit threshold of the force is less than the preset pressure value, which is used to limit the residual pressure force of the compression component on the chest.

2. The automatic cardiopulmonary resuscitation device according to claim 1, characterized in that, The drive assembly includes a servo motor (1) fixed to one side of the outer sleeve (8); The transmission assembly includes a synchronous belt (3), a first synchronous pulley (4), and a second synchronous pulley (5); The first synchronous pulley (4) is connected to the second synchronous pulley (5) via a synchronous belt (3); The output shaft of the servo motor (1) is connected to the first synchronous pulley (4); The second synchronous pulley (5) is connected to the reversible drive mechanism.

3. An automatic cardiopulmonary resuscitation device according to claim 2, characterized in that, The reversible drive mechanism includes a ball screw (10). The pressing assembly includes a connected inner sleeve (11) and a pressing head (12). One end of the ball screw (10) is connected to the second synchronous pulley (5), and the other end is connected to the inner sleeve (11) through the screw nut; The inner sleeve (11) and the pressing head (12) can move along the pressing axis within the cavity of the outer sleeve (8).

4. An automatic cardiopulmonary resuscitation device according to claim 3, characterized in that, The outer sleeve (8) cavity is also provided with a gravity compensation component to counteract the gravity of the pressing component and the reversible drive transmission mechanism; The gravity compensation component includes a spring (9); the spring (9) is coaxially sleeved on the ball screw (10); one end of the spring (9) is fixed to the top or middle fixing ring of the outer sleeve (8), and the other end is fixed to the inner sleeve (11), which is used to provide an upward elastic force in the event of power failure or when the servo motor has no torque output, so that the pressing component can automatically retract to the upper stop point or remain in a suspended state; the elastic force satisfy: In the formula, The total weight of the pressing component and the reversible drive mechanism; It is the equivalent static friction force of the system when it is at rest or at low speed.

5. An automatic cardiopulmonary resuscitation device according to claim 3, characterized in that, The monitoring unit includes a position sensor (15) and a force sensor; The position sensor (15) is connected to the outer sleeve (8); The inner sleeve (11) has protrusions on its outer wall. When the inner sleeve (11) moves along the pressing axis, the protrusions come into contact with the position sensor (15) so that the position sensor (15) can collect the pressing depth of the pressing component. The force sensor is located at the connection between the inner sleeve (11) and the pressing head (12) or integrated inside the pressing head (12), and can collect the contact force between the pressing component and the patient's chest. The monitoring unit also includes travel limit and safety detection elements.

6. An automatic cardiopulmonary resuscitation device according to claim 5, characterized in that, The travel limit and safety detection elements are located near the upper and lower dead points of the inner sleeve (11), including a travel switch, a proximity switch or a Hall sensor, to detect whether the pressing component has reached the safe travel boundary, and to issue an alarm or stop driving in abnormal situations.

7. A control method for an automated cardiopulmonary resuscitation (CPR) device, based on the automated CPR device according to any one of claims 1-6, characterized in that, include: S1: Press Downward Control: The controller controls the drive component to drive the pressing component downward along a preset speed trajectory, using a position or speed closed-loop control mode, until the target pressing depth is reached; S2: Phase switching detection: Real-time monitoring of changes in pressing depth and / or contact force. When the lower stop point is reached or the phase switching condition is met, the system switches to the rebound follow control mode. S3: Rebound Follow-up Control: The controller adopts force closed-loop control, impedance control or admittance control strategies; S4: Real-time adjustment: In step S3, the actual contact force between the compression component and the chest is obtained in real time. Or equivalent load torque; S5: The controller adjusts the torque of the drive assembly based on the actual contact force. like Greater than the upper limit of the near-zero force window The control drive components increase the upward auxiliary torque to eliminate the reliance on the thorax; like Less than the lower limit of the near-zero force window The control drive components reduce the upward torque or apply a downward following torque to track the thoracic rebound and prevent slippage. S6: Cycle determination: When the pressing component rebounds with the chest cavity to the upper stop point or reaches the preset rebound time, proceed to step S1 of the next cycle.

8. The control method for an automatic cardiopulmonary resuscitation device according to claim 7, characterized in that, In step S3, the output torque command of the drive component Including friction feedforward compensation and force feedback adjustment terms, the specific control law formula is as follows: In the formula, Based on the current rebound speed The system dynamic friction feedforward compensation is used to counteract the dynamic friction resistance of the mechanical transmission system. For gravity compensation residuals, it is used to compensate for the trace amounts of gravity that are not completely offset by the gravity compensation components; , These are the proportional and differential gains for force control, respectively; The target contact force is set within a near-zero force window; This is the measured contact force.

9. The control method for an automatic cardiopulmonary resuscitation device according to claim 8, characterized in that, The control method further includes: The specific steps for friction model identification and correction are as follows: During the device's power-on self-test or idle phase, the pressing component is driven to run unloaded, and the current value of the servo motor (1) at different speeds is recorded to construct a speed-friction torque curve. The drive component is a servo motor (1). During actual pressing, the friction feedforward compensation is updated online based on the integral or mean of the force error. The parameters are adjusted to accommodate the drift in frictional characteristics caused by device wear or temperature changes.

10. The control method for an automatic cardiopulmonary resuscitation device according to claim 8, characterized in that, The control method further includes: The specific steps of the thoracic wall compliance adaptation process are as follows: During the compression process in step S1, force-displacement data is recorded, and the current chest stiffness coefficient of the patient is calculated based on the force-displacement data. Based on the thoracic stiffness coefficient, the control parameters of the rebound following control in step S3 are adaptively adjusted to improve the sensitivity of the device's following response.

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