A robotic arm based on a spatial orthogonal worm gear composite transmission architecture

Abstract

This invention discloses a robotic arm based on a spatial orthogonal worm gear composite transmission architecture for a handheld intelligent vascular puncture system, comprising: a puncture arm mechanism (1) for receiving instructions from the control system, accurately and smoothly converting the rotational motion of the motor into linear puncture needle advance and retraction motion, and providing real-time feedback on puncture depth; including a drive device and a puncture system architecture; a puncture arm angle adjustment mechanism (2) for accurately and stably adjusting and locking the attitude angle of the puncture arm in space based on at least two degrees of freedom of pitch and yaw angle; wherein the puncture arm angle adjustment mechanism (2) adopts a small-volume, high-power-density hollow cup motor, combined with a precision planetary reducer and a self-locking spatial orthogonal worm gear composite transmission architecture; a needle clamp (3) made of medical polycarbonate PC-MR material injection molding and a needle guide (4) made of medical polyethylene resin G232BT (Q281) material injection molding and a continuous stability guarantee system for the puncture mechanism (5).

Description

Technical Field

[0001] This invention relates to the field of medical device optimization technology, and in particular to a robotic arm based on a spatial orthogonal worm gear composite transmission architecture. Background Technology

[0002] Establishing vascular access promptly is crucial for trauma care, ensuring the timely infusion of emergency medications, analgesics, and fluids. While peripheral intravenous catheters play a key role in fluid resuscitation, central venous catheters not only provide stable and reliable vascular access but also enable large-volume fluid resuscitation and facilitate invasive endovascular treatments. Whether at the scene of the injury, during medical transport, in the emergency room, or at a military frontline surgical base, the ability to establish vascular access promptly directly determines the timing of emergency care. For cases with the longest transport times, timely establishment of central venous access often yields the greatest results. However, such procedures typically require experienced medical personnel.

[0003] In a hospital setting, intensive care physicians are typically far from the scene of the injury. Major obstacles to establishing central venous access on-site include a lack of advanced ultrasound image interpretation skills and insufficient proficiency in image-guided venous catheter insertion. Healthcare workers with weak foundational venous access techniques are unable to establish central venous access effectively in pre-hospital emergency settings.

[0004] Establishing central venous access is more challenging than peripheral venous access because the vessels are located deeper, making direct observation and manual palpation difficult. Major arterial structures are often adjacent to the target vein, increasing the risk of accidental arterial injury. Despite these risks and procedural complexities, over three million central venous catheters are inserted annually in China. While ultrasound-guided central venous catheterization has significant value, it is rarely performed in pre-hospital emergency settings due to the extensive training and practice required for both ultrasound image interpretation and catheter insertion. Standard Serdinger technique catheter insertion involves several steps: ① puncture of the target vessel, ② placement of a coaxial guidewire, ③ needle removal, ④ repeated dilation of the puncture site as needed, ⑤ catheter insertion via the guidewire, and ⑥ guidewire removal. The initial puncture is the most skill-intensive and prone to failure step. Furthermore, successful guidewire insertion and needle withdrawal almost guarantee the success of subsequent steps and eliminate the risk of needle injury.

[0005] Vascular puncture is a fundamental procedure in clinical and emergency care, but its success rate is highly dependent on the operator's experience. This is especially true in patients who are obese, have low blood pressure, or suffer from arteriosclerosis, as their blood vessels are often hidden, collapsed, or highly mobile, increasing the failure rate. In extreme conditions such as in the field, on the battlefield, or at night, where lighting, space, and personnel are limited, traditional manual procedures cannot guarantee both timeliness and safety.

[0006] Currently, the field of vascular puncture robots is still in its developmental stage both domestically and internationally. Most systems focus on peripheral vascular operations (such as blood collection), and their technical forms are mostly "image recognition + manual execution" or "semi-automatic assistance" modes, with the overall level of intelligence still in its early stages. In the high-risk, deep, and more precise path requirements of central venous puncture, no clinical products have yet achieved a closed-loop control system that truly integrates "image recognition + path planning + intelligent puncture." A lightweight, portable, intelligent, and integrated vascular puncture system remains a global void.

[0007] Furthermore, as the most important structural component of the system, the design of the robotic arm mechanism cannot significantly improve the success rate, timeliness, and safety. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides the following technical solution: a robotic arm based on a spatial orthogonal worm gear composite transmission architecture, which significantly improves the success rate, efficiency, and safety of traditional robotic arms.

[0009] This invention provides a robotic arm based on a spatial orthogonal worm gear composite transmission architecture for use in a handheld intelligent vascular puncture system, comprising:

[0010] The puncture arm mechanism (1) includes a linear rectangular multi-faceted auxiliary guide rail (11), a double-headed rectangular lead screw (12), an integrated slider lead screw nut (13), a precision planetary reducer (14), and a hollow cup motor (15). It is used to receive instructions from the control system, accurately and smoothly convert the rotational motion of the motor into the linear puncture needle advance and retraction motion, and provide real-time feedback on the puncture depth. The puncture arm mechanism (1) includes a drive device and a puncture system architecture. The drive device is composed of a small-volume, high-power-density hollow cup motor, a planetary reducer, and a double-headed rectangular lead screw. The puncture system architecture is composed of an integrated slider lead screw nut and a linear rectangular multi-faceted auxiliary guide rail (11). The puncture system architecture is a transmission and guidance architecture, used to convert the rotational motion of the double-headed rectangular lead screw into linear motion and bear all radial forces and torques generated during the puncture process, ensuring the accuracy and stability of the motion trajectory.

[0011] The puncture arm angle adjustment mechanism (2) is used to precisely and stably adjust and lock the attitude angle of the puncture arm in space based on at least two degrees of freedom: pitch angle and yaw angle; wherein, the puncture arm angle adjustment mechanism (2) adopts a small volume high power density hollow cup motor, combined with a composite transmission architecture of precision planetary reducer and self-locking spatial orthogonal worm gear;

[0012] The needle clamp (3) includes the needle clamp body (31), which is injection molded from medical polycarbonate PC-MR material;

[0013] The guide needle (4) includes the guide needle body (41), which is formed by injection molding using medical polyethylene resin G232BT(Q281); wherein, the material identification of G232BT(Q281) includes the enterprise's custom grade and the corresponding national standard performance level.

[0014] The continuous stability assurance system (5) for the puncture mechanism uses an image acquisition device to acquire real-time motion images of the puncture arm mechanism, and realizes visual jitter state recognition and quantification based on a first algorithm; and realizes motion smooth control and risk warning based on fifth-order polynomial interpolation based on a second algorithm; wherein the visual jitter state recognition and quantification includes: identifying the jitter state based on the analysis of the real-time motion images and accurately quantifying the jitter amplitude; wherein the motion smooth control and risk warning based on fifth-order polynomial interpolation includes: planning the acceleration curve through the fifth-order polynomial interpolation algorithm to realize smooth control of the motion process, and establishing a risk warning mechanism, correcting and calibrating the motion position in real time through the position command closed-loop control system to ensure that the puncture mechanism reaches the target position; and timely avoiding operational risks caused by jitter through the feedforward and feedback PID composite algorithm.

[0015] Preferably, in the drive device, the hollow cup motor is a brushless DC hollow cup motor, and the planetary reducer is a precision micro planetary gear reducer used for torque amplification and speed reduction. The planetary reducer and the hollow cup motor are directly connected through a standard flange interface to form a compact "motor + reducer" module. The planetary reducer is directly fixed to the front end cover of the hollow cup motor through a stop and screws. The input shaft of the planetary reducer is connected to the motor shaft of the hollow cup motor through a set screw or knurled fit. The double-ended rectangular lead screw is a precision-ground double-ended rectangular threaded lead screw used for motion conversion. The output shaft of the planetary reducer has a connecting hole machined inside. The input end of the double-ended rectangular lead screw is machined into a smooth shaft or a shaft with a keyway, and is rigidly connected to the output shaft of the planetary reducer through a high-precision set screw or a flexible coupling. The shoulder of the double-ended rectangular lead screw is positioned by the inner ring of the bearing at the output end of the planetary reducer.

[0016] Preferably, in the puncture system architecture, the integrated slider screw nut serves as a motion actuator, consisting of an integrated slider and a screw nut. The integrated slider is a cuboid or cubic metal block. A threaded hole precisely matching the double-headed rectangular screw is machined at the center of the integrated slider, serving as the screw nut. A slider groove or mounting hole that mates with the linear rectangular multi-faceted auxiliary guide rail (11) is machined on the bottom or side of the integrated slider. The linear rectangular multi-faceted auxiliary guide rail (11) of the puncture system architecture is a square linear sliding guide rail or a double prism guide rail, used as a guiding system that forms surface contact with the guiding and load-bearing mechanism.

[0017] Preferably, the linear rectangular multi-faceted guide rail (11) includes a guide rail and a guide rail groove corresponding to the slider groove; the guide rail is fixed parallel to the body or base of the piercing mechanism to provide a precise linear reference; the guide rail groove includes a rectangular groove machined on the integral slider to precisely match the guide rail, the rectangular groove is a multi-faceted pair in the form of surface contact, and the integral slider is set on the two guide rails through the multi-faceted pair.

[0018] Preferably, the design process of the puncture arm mechanism (1) includes:

[0019] (1) Based on engineering principles, a 3D model of the puncture mechanism was created using SolidWorks to demonstrate the model's geometric dimensions, manufacturability, and functional requirements.

[0020] (2) Static simulation is performed using ANSYS to predict the strength and stability of the structure;

[0021] (3) Utilizing the principle of converting the continuity of mechanical motion into the discreteness of electrical signals, an incremental magnetic encoder is used to monitor the puncture depth based on reading the number of rotations and angle of the motor; wherein, the incremental magnetic encoder is installed at the tail end of the hollow cup motor opposite to the reducer; the hollow cup motor, the planetary reducer, the double-headed rectangular threaded screw and the incremental magnetic encoder form a coaxial series relationship.

[0022] Preferably, in the spatial orthogonal worm gear, the worm shaft and the worm wheel shaft are intersected at a 90-degree angle in three-dimensional space and are not in the same plane; for the degree of freedom adjustment of the yaw angle, the horizontal angle adjustment is achieved by adjusting the yaw axis; for the degree of freedom adjustment of the pitch angle, the vertical pitch angle adjustment is achieved by adjusting the pitch axis, thereby positioning the end of the puncture arm to any desired angle in space by controlling the coordinated movement of the two motors;

[0023] The precision planetary reducer is a miniature low-backlash planetary gear reducer used for primary speed reduction and torque amplification. It is directly integrated with the motor via a standard flange to form a compact "motor-reducer integrated module", thereby performing primary speed reduction and torque amplification between the motor and the worm gear pair.

[0024] Preferably, the self-locking spatial orthogonal worm gear is the core transmission and self-locking functional component, comprising:

[0025] A single-start worm gear, one end of which is connected to the output shaft of the precision planetary reducer via a flexible coupling or a precision set screw;

[0026] The split worm gear has an involute or ZA-type tooth profile that is precisely matched with the single-headed worm.

[0027] The self-locking condition is to establish a spatial orthogonal worm gear self-locking critical angle based on the Coulomb friction model. The critical condition for self-locking is that the lead angle γ of the worm is less than or equal to the equivalent friction angle ρ of the worm gear pair. The formula for calculating the lead angle γ is shown in equation (1).

[0028] γ = arctan(lead / (π*worm pitch circle diameter)) = arctan(module*number of heads / pitch circle diameter) (1);

[0029] The formula for calculating the equivalent friction angle ρ is shown in equation (2):

[0030] ρ=arctan(μ) (2;

[0031] Where μ is the coefficient of friction, which is determined by material pairing and lubrication conditions.

[0032] Preferably, the design process of the puncture arm angle adjustment mechanism (2) includes:

[0033] (1) Based on engineering principles, a 3D model of the angle adjustment mechanism was created using SolidWorks to demonstrate the model's geometric dimensions, manufacturability, and functional requirements; including: detailed modeling of all parts; interference and clearance checks to ensure appropriate worm gear meshing clearance and no collisions among all moving parts; quality property analysis to optimize weight distribution and ensure hand-held balance; and design of bearing housings, using miniature deep groove ball bearings to support the worm and worm gear shaft to ensure smooth rotation and rigidity; all parts include: bracket, bearing housing, and housing;

[0034] (2) Static simulation is performed using ANSYS to predict the strength and stability of the structure; a self-locking critical angle of the spatial orthogonal worm gear is calculated based on the Coulomb friction model to construct stable and reliable self-locking conditions and ensure self-locking performance; in this embodiment, static simulation is used to simulate the torque experienced by the puncture arm when it is at the maximum lever arm position, and to verify whether the stress and deformation of the worm gear root, worm shaft and support are within the safe range under the maximum working load; the static simulation process includes:

[0035] A. Material Assignment: Assigning correct material properties to each component;

[0036] B. Constraints and Loads: With the mounting surface of the fixed base, apply a torque ≥0.3 N·m to the output end of the worm gear;

[0037] C. Results analysis, including using stress cloud diagrams to check whether the maximum equivalent stress is lower than the material's yield strength, with a safety factor generally required to be greater than 1.5; and using deformation cloud diagrams to check the maximum deformation, ensuring that it is much smaller than the accuracy requirements for angle adjustment.

[0038] (3) An incremental magnetic encoder is used to monitor the angular position and perform repeatability positioning accuracy testing; the incremental magnetic encoder is usually installed at the non-output end of the motor tail and is used to measure the rotation angle of the motor; the encoder reads the angular displacement of the motor shaft;

[0039] (4) A miniature mechanical position detection sensor is used to perform zeroing after each angle adjustment to avoid the accumulation of cumulative errors, thereby achieving the functions of absolute position reference and cumulative error elimination. The miniature mechanical position detection sensor includes: miniature limit switch, Hall sensor or photoelectric sensor; the zeroing process includes: after the system starts or completes an angle adjustment, the controller will drive the puncture arm to move slowly towards a preset mechanical origin; when the origin sensor in that direction is triggered, the motor stops immediately; the controller will force the encoder count value at this time to be set to the absolute zero position coordinate.

[0040] Preferably, the vision-based jitter state recognition and quantification based on the first algorithm includes:

[0041] S1, Marker Detection and Tracking, is used to accurately find the center coordinates of pre-defined markers in each frame of the image, including:

[0042] Setting the ROI (Region of Interest) includes: manually or automatically setting a region containing marker points in the first frame;

[0043] Image preprocessing includes: grayscale conversion, Gaussian filtering, and contrast enhancement of the image within the ROI to improve the signal-to-noise ratio;

[0044] Feature extraction is performed: a sub-pixel-level corner detection algorithm or template matching algorithm is used to calculate the image coordinates of the center of the marker point, where t is the current timestamp;

[0045] S2, Motion Data Transformation and Filtering, is used to convert image coordinate sequences into physical world displacement sequences and separate useful signals from noise, including:

[0046] Camera calibration includes: calibrating the camera using a calibration plate to obtain intrinsic and extrinsic parameters; and converting the image coordinates of the marked points into their actual displacements in a two-dimensional measurement plane through perspective transformation.

[0047] Data filtering includes: smoothing using a low-pass digital filter;

[0048] S3, jitter feature extraction and quantization, is used to extract key indicators characterizing the degree of jitter from smoothed displacement data, including:

[0049] Generating the ideal trajectory includes: generating a theoretically ideal displacement-time curve based on motion control commands, which is a sloping line for uniform puncture and a planned curve given by the controller for variable speed motion;

[0050] The calculation of jitter error includes: calculating the difference between the actual displacement and the ideal displacement to obtain the jitter error e(t). The e(t) sequence is the direct manifestation of jitter.

[0051] Calculate quantitative indicators, including:

[0052] Calculate the jitter amplitude: directly calculate the peak value or root mean square value of the error sequence e(t);

[0053] Calculate the jitter frequency: Perform a fast Fourier transform on the error sequence e(t) to convert the time-domain signal to the frequency domain, and analyze the spectrum to obtain the main frequency components of the jitter;

[0054] Calculate jitter acceleration: Perform second-order numerical differentiation on the displacement data to calculate the acceleration and analyze its changes. Sudden changes in acceleration are the direct cause of jitter and impact force.

[0055] Preferably, the motion smoothing control and risk warning based on fifth-order polynomial interpolation using the second algorithm includes:

[0056] S1, performs fifth-order polynomial interpolation, including:

[0057] (1) Setting boundary conditions: For a motion segment from time t=0 to t=T, six boundary conditions need to be met, as follows:

[0058] s(0) = 0 (starting position)

[0059] s(T) = S (target position)

[0060] v(0) = v0 (initial velocity)

[0061] v(T) = vT (final velocity)

[0062] a(0) = a0 (Initial acceleration)

[0063] a(T) = aT (final acceleration)

[0064] To ensure a smooth start and end, let v0 = vT = 0; a0 = aT = 0.

[0065] (2) Construct a fifth-degree polynomial:

[0066] The displacement equation is set as: s(t) = a0 + a1*t + a2*t 2 +a3*t 3 +a4*t 4 +a5*t 5 ;

[0067] Differentiating these values ​​yields the velocity v(t) and acceleration a(t); substituting the six boundary conditions into the system of equations, we can solve for the six unique coefficients a0 to a5.

[0068] S2, generating real-time trajectory, including: in each control cycle, the controller calculates the desired position s(t) corresponding to the current time t according to the calculated polynomial coefficients, and sends it as an instruction to the motor driver;

[0069] S3, based on adaptive smoothing control combined with jitter feedback, includes:

[0070] (1) When the jitter amplitude is detected to exceed the threshold, the planned motion time T is actively extended;

[0071] (2) Implement frequency-based suppression, including: if FFT analysis finds that jitter occurs continuously at a certain frequency, add a notch filter for that frequency to the pre-filter of the motion planner to weaken the excitation of that frequency in advance at the instruction level.

[0072] The robotic arm provided by this invention has the following beneficial effects:

[0073] 1. In the piercing arm mechanism (1), the integrated slider screw nut is not a separate nut part, but rather integrates the functions of the screw nut and the slider into a single metal block. The beneficial effects include:

[0074] (1) Eliminate assembly errors: Traditional split design (nuts are manufactured separately and then installed on the slider) will introduce concentricity and parallelism errors. The integrated design ensures that the thread center line of the nut is absolutely parallel to the sliding direction of the guide rail, fundamentally avoiding "stiffness" and additional wear.

[0075] (2) High rigidity: The structure is compact and the overall rigidity is much higher than that of the split structure.

[0076] (3) Reduced size and weight: The number of parts and connectors has been reduced, which meets the requirements for miniaturization of medical devices.

[0077] 2. The puncture arm angle adjustment mechanism is a highly sophisticated mechatronic design that not only meets the stringent requirements of precision and stability in vascular puncture surgery, but its built-in safety self-locking feature also ensures the safety of the surgical procedure. This embodies the core principles of medical device design, specifically reflected in:

[0078] (1) Power and transmission chain: The hollow cup motor provides power, the planetary reducer provides initial speed increase, and the self-locking spatial orthogonal worm gear pair serves as the core transmission, achieving a huge total reduction ratio, extremely high output torque and absolutely reliable mechanical self-locking.

[0079] (2) Structural layout: The spatially orthogonal composite transmission architecture makes the structure extremely compact and perfectly suited to the miniaturization requirements of handheld devices.

[0080] (3) Control and accuracy: The incremental magnetic encoder provides extremely high angular resolution, while the mechanical origin sensor periodically eliminates accumulated errors, together ensuring long-term repeatability positioning accuracy.

[0081] (4) Engineering verification: Using tools such as SolidWorks and ANSYS, the geometric dimensions, manufacturability, structural strength and stiffness were fully simulated and verified during the design phase to ensure the reliability and performance of the product.

[0082] 3. The continuous stability assurance system for the puncture mechanism is a highly intelligent closed-loop control system. It accurately senses mechanical vibrations through machine vision, quantifies them into specific parameters through signal processing, and then uses an advanced motion planning algorithm—five-order polynomial interpolation—to generate smooth, shock-free motion commands from the source. Finally, a multi-level risk warning mechanism ensures that the system can proactively intervene in abnormal situations to guarantee safety. This algorithm process elevates the traditional "open-loop execution" to a fully closed-loop intelligent control system encompassing "perception-decision-execution-safety," fully demonstrating the high precision and high reliability of this vascular puncture robot system. Attached Figure Description

[0083] Figure 1 This is a cross-sectional view of the robotic arm described in this invention.

[0084] Figure 2 This is a front view of the structure of the robotic arm described in this invention;

[0085] Figure 3 This is a left view of the structure of the robotic arm described in this invention;

[0086] Figure 4 This is a three-dimensional structural diagram of the robotic arm described in this invention;

[0087] Figure 5 This is a schematic diagram of the puncture arm mechanism described in this invention;

[0088] Figure 6 This is a schematic diagram of the linear rectangular multi-faceted sub-guide rail structure described in this invention;

[0089] Figure 7 This is a schematic diagram of the puncture arm angle adjustment mechanism described in this invention;

[0090] Figure 8 This is a schematic diagram of the sidewall guide structure described in this invention;

[0091] Figure 9 (a) and Figure 9 (b) is a schematic diagram of the needle clamp structure of the present invention and a schematic diagram of the structural components assembled thereon;

[0092] Figure 10 (a) and Figure 10 (b) is a schematic diagram of the guide needle structure of the present invention and a schematic diagram of the structural components assembled thereon;

[0093] Figure 11 This is a schematic diagram of the working principle of the position command closed-loop control system described in this invention;

[0094] Figure 12 This is a flowchart of the feedforward and feedback PID composite algorithm described in this invention. Detailed Implementation

[0095] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0096] like Figure 1-4 As shown, this embodiment provides a robotic arm based on a spatial orthogonal worm gear composite transmission architecture for a handheld intelligent vascular puncture system, comprising:

[0097] like Figure 5 The puncture arm mechanism 1 shown includes, as follows: Figure 6The linear rectangular multi-faceted auxiliary guide rail 11, double-headed rectangular lead screw 12, integrated slider lead screw nut 13, precision planetary reducer 14, and hollow cup motor 15 shown are used to receive instructions from the control system, accurately and smoothly convert the rotational motion of the motor into linear puncture needle advance and retraction motion, and provide real-time feedback on puncture depth. Its design goals are high precision, high rigidity, no backlash, low friction, miniaturization, and lightweight; the puncture arm mechanism (1) includes a drive device and a puncture system architecture; wherein, the drive device is composed of a small-volume, high-power-density hollow cup motor, a planetary reducer, and a double-headed rectangular lead screw (pitch 1.2mm); the puncture system architecture is composed of an integrated slider lead screw nut and a linear rectangular multi-faceted auxiliary guide rail 11.

[0098] In a preferred embodiment, the drive device is the power source and motion conversion core of the entire puncture mechanism, and its composition and working process are as follows:

[0099] 1. The aforementioned small-volume, high-power-density hollow core motor, used as a power source, is a brushless DC hollow core motor. This is the preferred choice for high-end precision medical devices. Compared with traditional iron-core motors, hollow core motors have the following absolute advantages:

[0100] (1) High power density: The rotor has no iron core, eliminating iron losses (eddy current losses and hysteresis losses), and the efficiency can reach more than 90%. Under the same volume, it can output more power, which is very suitable for handheld devices with extremely strict space requirements.

[0101] (2) Low inertia and fast response: The rotor has very low inertia and a very fast response speed for starting and stopping, which can achieve precise instantaneous control, which is crucial for puncture operations that require rapid positioning and emergency stopping.

[0102] (3) No cogging effect: The operation is extremely stable with small torque fluctuations, avoiding the "jerkiness" that may occur during low-speed puncture and ensuring smooth movement.

[0103] (4) Hollow structure: The hollow design of the motor can provide a path for subsequent possible cables (such as sensor lines, optical fibers that may be integrated in the future, etc.) and optimize the internal wiring.

[0104] Example of specific parameters:

[0105] Outer diameter: usually in the range of 10mm-20mm, for example, a motor with a diameter of 15mm is selected.

[0106] Length: Approximately 30mm-50mm.

[0107] Rated voltage: 12V or 24VDC, in compliance with medical device safety standards.

[0108] Rated torque: Calculated based on the load, it needs to overcome the friction of the lead screw and nut pair and the tissue resistance encountered by the puncture needle. Expected to be in the range of 5-10 mNm.

[0109] Rated speed: Typically high, reaching 8000-10000 RPM. High speed combined with a reducer is necessary to obtain large output torque.

[0110] Control method: Equipped with a high-performance servo drive, using the FOC (Field Oriented Control) algorithm to achieve precise torque, speed and position control.

[0111] 2. The planetary reducer is used for torque amplification and speed reduction, and adopts a precision micro planetary gear reducer. Due to its compact structure, high rigidity, low backlash, and high transmission efficiency, and the coaxial input and output shafts, the planetary reducer is directly connected to the hollow cup motor to form a compact "motor + reducer" module.

[0112] Functions of planetary gear reducers:

[0113] (1) Increase torque: Convert the high speed and low torque of the motor into low speed and high torque to meet the high torque output required for puncture.

[0114] (2) Improve controllability: reduce the value of load inertia reflected on the motor shaft, making the system easier to control and more stable.

[0115] Examples of specific parameters (matching the motor):

[0116] Reduction ratio: Calculated based on the puncture speed and required thrust. For example, select a reduction ratio of 10:1 or 15:1.

[0117] Calculation example: If the motor's rated speed is 10000 RPM, after a 10:1 reduction ratio, the output speed is 1000 RPM. For a leadscrew with a pitch of 1.2 mm, the theoretical puncture speed is 1000 rpm * 1.2 mm / r = 1200 mm / min = 20 mm / s. This speed is suitable for a controllable puncture operation.

[0118] Backlash: Select a low backlash model, typically less than 1 arc minute, to ensure positioning accuracy during forward and reverse rotation and avoid retrace error.

[0119] Installation method: It is directly fixed to the front cover of the hollow cup motor by means of a stop and screws. The input shaft of the reducer is connected to the motor shaft by set screws or knurling.

[0120] 3. Double-ended rectangular lead screw (1.2mm pitch), used for motion conversion, employing a precision-ground double-ended rectangular threaded lead screw. Compared to common ball screws and trapezoidal lead screws, the advantages of rectangular lead screws in this application include:

[0121] (1) Self-locking property: The lead angle of the rectangular thread is small. When the lead angle is less than the friction angle, it has good self-locking performance. This means that after the motor is powered off, the position of the puncture needle can be reliably locked and will not move backward due to external forces (such as tissue rebound force). This is a key guarantee for surgical safety. Thus, the goal of "building stable and reliable self-locking conditions" is achieved.

[0122] (2) High rigidity: The thread profile is rectangular, with a large contact area, strong load-bearing capacity, high rigidity, and small deformation when subjected to puncture force.

[0123] (3) Simple structure and controllable cost: Although its efficiency is lower than that of ball screw, its performance is sufficient and more economical for puncture motion with short stroke and low speed.

[0124] The innovation of the "dual-head" design lies in:

[0125] (1) Increase lead: Double-ended thread means that for every revolution of the lead screw, the nut advances a distance of two thread pitches. While maintaining the same thread pitch (1.2mm), the lead becomes 2.4mm. This can increase the piercing speed without increasing the lead screw speed, or reduce the motor speed and run more smoothly while maintaining the same piercing speed requirement.

[0126] (2) Improved balance: The double-ended thread makes the nut more symmetrically stressed and the movement more stable.

[0127] Specific parameters include:

[0128] Nominal diameter: Depending on the load and stiffness requirements, 6mm or 8mm may be selected.

[0129] Pitch: Specifically 1.2mm. This is a fine thread, which is beneficial for achieving high-precision control (for every 1° rotation of the motor, the nut moves only 2.4mm / 360°≈0.0067mm) and self-locking.

[0130] Material: Usually stainless steel (such as SUS440C or SUS304), which has high hardness, wear resistance and corrosion resistance, meeting the requirements of medical devices.

[0131] Manufacturing process: Precision grinding rather than rolling is used to ensure the accuracy of the threads and the surface finish.

[0132] 4. The connection method of the three:

[0133] (1) Motor and reducer: connected through a standard flange interface to form an integrated module.

[0134] (2) Reducer and lead screw: The output shaft of the planetary reducer has a connecting hole machined inside. The input end of the double-ended rectangular lead screw is machined into a smooth shaft or a shaft with a keyway, and is rigidly connected to the output shaft of the reducer through a high-precision set screw or a flexible coupling. To ensure coaxiality, the lead screw shoulder is positioned by the inner ring of the bearing at the output end of the reducer.

[0135] As a preferred embodiment, the puncture system architecture is a transmission and guidance architecture, which is used to convert the rotational motion of the lead screw into pure linear motion and bear all radial forces and torques generated during the puncture process, ensuring the accuracy and stability of the motion trajectory.

[0136] The puncture system architecture uses an integrated slider screw nut as a motion actuator. The integrated slider is a cuboid or cubic metal block (such as aluminum alloy or copper alloy). The center of the integrated slider is machined with a threaded hole that precisely matches the double-ended rectangular screw as the screw nut. The bottom or side of the integrated slider is machined with a groove or mounting hole that mates with a linear guide rail.

[0137] The linear rectangular multi-faceted sub-guide rail 11 of the puncture system architecture serves as a guide and load-bearing mechanism, which is either a square linear sliding guide rail or a double prism guide rail, thereby forming a surface contact guide system.

[0138] The linear rectangular multi-faceted guide rail 11 includes corresponding grooves on the guide rail and the slider; the guide rail consists of two precision-ground rectangular steel bars with rectangular cross-sections, fixed parallel to each other on the body or base of the piercing mechanism to provide a precise linear reference; the groove includes a rectangular slot machined on the integrated slider to precisely match the two rectangular guide rails, the rectangular slot being a multi-faceted pair in the form of V-shaped, rectangular, or other surface contact, and the integrated slider is mounted on the two guide rails through the multi-faceted pair.

[0139] In this embodiment, the working mode and advantages of using the linear rectangular multi-faceted sub-guide rail 11 are as follows:

[0140] (1) High rigidity and high stability: The surface contact support method can withstand radial forces and overturning moments from all directions. During the puncture process, the needle tip may generate lateral forces when it encounters tissues of different densities. This guide rail can greatly suppress shaking and swaying.

[0141] (2) No shaking: Through the pre-tightening design, the gap between the slider and the guide rail can be completely eliminated, achieving smooth movement with zero shaking.

[0142] (3) Self-cleaning ability: Compared with ball bearing guides, sliding guides are less likely to be stuck by dust or tissue debris, and dust covers can be designed when necessary.

[0143] In this embodiment, a double-headed rectangular lead screw rotates, driving an integrated slider to move along the lead screw axis. The rectangular groove on the integrated slider precisely engages with two parallel rectangular guide rails fixed to the base, constraining the slider to perform only purely linear motion along the guide rails, preventing rotation or lateral movement. The puncture needle holder is mounted on this integrated slider. Therefore, the precise linear motion of the slider is directly converted into the linear advance and retreat of the puncture needle.

[0144] As a preferred embodiment, the design process of the puncture arm mechanism 1 includes:

[0145] (1) Based on engineering principles, a 3D model of the puncture mechanism was created using SolidWorks to demonstrate the model's geometric dimensions, manufacturability, and functional requirements.

[0146] (2) Static simulation is performed using ANSYS to predict the strength and stability of the structure;

[0147] (3) Utilizing the principle of converting the continuity of mechanical motion into discrete electrical signals, an incremental magnetic encoder is used for puncture depth monitoring; wherein, the incremental magnetic encoder is installed at the tail end of the hollow cup motor opposite to the reducer; the motor, reducer, lead screw, and encoder form a coaxial series connection; the incremental encoder reads the number of rotations and angle of the motor. Since the entire transmission chain is rigid (fixed reduction ratio, fixed lead screw lead), there is a strict linear relationship between the rotation angle of the motor and the linear displacement of the nut. The depth calculation is: puncture depth = (number of encoder pulses / number of pulses per revolution) * reduction ratio * lead screw lead:

[0148] For example, in this embodiment, the encoder has 1000 lines (4000 pulses per revolution), a reduction ratio of 10:1, and a lead screw of 2.4mm. Therefore, the displacement resolution corresponding to each pulse is (2.4mm / 10) / 4000 = 0.00006mm = 0.06µm, which is an extremely high theoretical resolution.

[0149] Compared to optical encoders, magnetic encoders are more resistant to vibration and contamination, and are smaller in size, making them more suitable for use in medical devices that may come into contact with bodily fluids or other harsh environments. Incremental encoders cannot record the absolute position after a power outage, requiring the system to be "zeroed" each time it is powered on. Over long-term operation, pulse counting errors may accumulate due to interference. Therefore, a miniature sensor, such as a microswitch or photoelectric proximity sensor, is placed at the travel limit of the puncture mechanism (usually the zero point). This miniature, mechanical position detection sensor resets the encoder's initial position after each puncture, preventing the accumulation of errors.

[0150] Workflow:

[0151] Before each surgery begins or after the puncture needle is withdrawn, the system initiates a "zeroing" procedure.

[0152] The motor drives the slider to move slowly toward the zero point;

[0153] When the slider touches the micro switch or blocks the light beam of the photoelectric sensor, the sensor sends a signal;

[0154] Upon receiving this signal, the controller resets the encoder's count value to a preset zero point value, thereby eliminating any accumulated errors and ensuring that each puncture begins from a precise absolute reference point.

[0155] The robotic arm also includes, for example, Figure 7 The puncture arm angle adjustment mechanism 2 shown includes a first spatial orthogonal worm gear 21, a second spatial orthogonal worm wheel 22, a worm wheel and worm gear housing 23, a planetary reducer 24 for the puncture arm angle adjustment mechanism, a hollow cup motor 25 for the puncture arm angle adjustment mechanism, and as shown in the figure. Figure 8 The sidewall guide structure 26 is shown.

[0156] In this embodiment, the overall scheme of the puncture arm angle adjustment mechanism 2 adopts a small-volume, high-power-density hollow cup motor, combined with a precision planetary reducer and a self-locking spatial orthogonal worm gear composite transmission architecture.

[0157] In this embodiment, the core function of the puncture arm angle adjustment mechanism is to precisely and stably adjust and lock the puncture arm's attitude angle in space. For delicate procedures like vascular puncture, at least two degrees of freedom adjustment are typically required: pitch and yaw. The embodiment of this invention employs a self-locking spatial orthogonal worm gear composite transmission architecture, integrating advantages such as high reduction ratio, high rigidity, compact size, and absolute self-locking.

[0158] 1. Overall layout and working principle of the composite transmission architecture

[0159] "Spatial orthogonal worm gear" means that the worm shaft and worm wheel shaft are intersected at a 90-degree angle in three-dimensional space and are not in the same plane. This is a very compact layout. For adjustments of two degrees of freedom, two such transmission mechanisms are usually used in series.

[0160] A typical two-degree-of-freedom (pitch + yaw) architecture layout:

[0161] (1) First stage (yaw axis adjustment):

[0162] Motor unit A (hollow cup motor + planetary reducer) is fixed on the main base of the equipment, with its output shaft placed horizontally. Motor unit A drives a worm gear A to rotate. Worm gear A meshes with a worm wheel A. The rotation axis of worm wheel A (i.e., the yaw axis) is spatially orthogonal to worm gear A, in a perpendicular direction. The hub of worm wheel A is fixed to a U-shaped bracket or turntable. When motor unit A is working, it drives the entire U-shaped bracket (and all subsequent components mounted on it) to rotate around the vertical axis (yaw axis), achieving horizontal angle adjustment.

[0163] (2) Second stage (pitch axis adjustment):

[0164] Motor unit B (hollow cup motor + planetary reducer) is mounted on one side plate of the aforementioned U-shaped bracket. Motor unit B drives a worm gear B to rotate. The axis of worm gear B is perpendicular to the side plate of the U-shaped bracket. Worm gear B meshes with a worm wheel B. The rotation axis (i.e., pitch axis) of worm wheel B is spatially orthogonal to worm gear B, and its axial direction is parallel to the opening direction of the U-shaped bracket. The hub of worm wheel B is fixedly connected to the fixed base of the puncture arm. When motor unit B is working, it drives the puncture arm to rotate around the pitch axis, achieving vertical pitch angle adjustment. By controlling the coordinated movement of the two motors, the end of the puncture arm can be positioned at any desired angle in space.

[0165] In a preferred embodiment, the small-volume, high-power-density hollow cup motor is used as a power source and is a brushless DC hollow cup servo motor.

[0166] The advantages of choosing a small-volume, high-power-density hollow cup motor include:

[0167] (1) High power density: Provides sufficient torque for angle adjustment while maintaining a very small size and weight, avoiding excessive strain on the wrist.

[0168] (2) Precise control: Its excellent controllability enables it to make minute angular steps and achieve fine adjustments.

[0169] (3) Stability: No tooth groove effect, smooth movement, avoiding jitter when adjusting the angle.

[0170] Specific parameters (for angle adjustment, torque requirement is lower than that of the puncture mechanism): Outer diameter: 10mm-12mm; Length: 20mm-30mm; Rated voltage: 12V DC; Rated no-load speed: 15000-20000 RPM; Rated torque: 3-5mNm; Peak torque: 10-15mNm.

[0171] As a preferred embodiment, the precision planetary reducer is a miniature low-backlash planetary gear reducer used for primary speed reduction and torque amplification. It is directly integrated with the motor via a standard flange to form a compact "motor-reducer integrated module", thereby performing primary speed reduction and torque amplification between the motor and the worm gear pair, reducing the input speed of the worm, increasing the output torque, and improving the control resolution and stability of the system.

[0172] Specific parameter examples (matching the motor): Reduction ratio: Select a higher reduction ratio, such as 19:1 or 26:1. This is because angle adjustment does not require very high speeds, but does require greater output torque and resolution. Backlash: ≤1 arc minute. Low backlash is crucial for angular positioning accuracy.

[0173] In a preferred embodiment, the self-locking spatial orthogonal worm gear serves as the core transmission and self-locking functional component, comprising:

[0174] (1) Worm: A single-start worm is used. This is the key to achieving the self-locking function. The lead angle of a single-start worm is small, making it easy to meet the self-locking condition (lead angle < friction angle). High-hardness and high-wear-resistance materials are used, such as stainless steel (e.g., 17-4PH), and the surface may be nitrided or quenched to increase hardness and wear resistance. Precision grinding ensures tooth profile accuracy and surface finish to reduce friction and noise. One end of the worm is connected to the output shaft of the planetary reducer via a flexible coupling or precision set screw. Using a flexible coupling can compensate for minor coaxiality errors.

[0175] (2) Worm Gear: A split structure is adopted. The rim is made of wear-resistant and friction-reducing materials, such as bronze (e.g., QAl9-4) or engineering plastics (e.g., POM polyoxymethylene), and the hub is made of steel or aluminum alloy. This ensures the friction performance of the meshing surface while reducing weight and cost. The involute or ZA type tooth profile is precisely matched with the worm. In this embodiment, the module is relatively small (e.g., 0.3-0.5), meshing with a single-start worm, thereby obtaining a huge reduction ratio. The reduction ratio calculation formula is: i = number of worm gear teeth / number of worm threads. If the number of worm gear teeth is 50 and the number of worm threads is 1, the reduction ratio is as high as 50:1.

[0176] (3) Engineering implementation and calculation of "self-locking":

[0177] Self-locking condition: "Establishing a self-locking critical angle for spatial orthogonal worm gears based on the Coulomb friction model" is a standard procedure in engineering design. The critical condition for self-locking is that the lead angle γ of the worm is less than or equal to the equivalent friction angle ρ of the worm gear pair.

[0178] The formula for calculating the lead angle γ is shown below:

[0179] γ = arctan(lead / (π*worm pitch circle diameter)) = arctan(module*number of heads / pitch circle diameter).

[0180] Equivalent friction angle ρ: ρ=arctan(μ), where μ is the friction coefficient, which depends on the material pairing (e.g., steel to bronze μ≈0.05-0.1) and lubrication conditions.

[0181] Design Validation: Engineers will calculate to ensure that γ < ρ. For example, designing a worm gear with γ = 3.5° and ρ estimated at 5° satisfies the self-locking condition. This means that it is impossible to drive the worm gear in reverse from the worm wheel side (efficiency less than 50%). Therefore, once the motor stops rotating, the angle of the puncture arm will be reliably locked by the worm gear pair and will not change due to gravity or external forces, which is an important guarantee for surgical safety.

[0182] (4) The structural advantage of “spatial orthogonal”: This layout allows the motor and reducer to be “hidden” inside or on the side of the bracket, which greatly saves space and makes the entire joint structure very compact, meeting the ergonomic requirements of handheld devices.

[0183] As a preferred embodiment, the design process of the puncture arm angle adjustment mechanism (2) includes:

[0184] (1) Based on engineering principles, a 3D model of the angle adjustment mechanism was created using SolidWorks to demonstrate the model's geometric dimensions, manufacturability, and functional requirements. This included: detailed modeling of all parts (bracket, bearing housing, and housing); interference and clearance checks to ensure proper worm gear meshing clearance and no collisions among moving parts; quality property analysis to optimize weight distribution and ensure hand-held balance; and design of bearing housings, using miniature deep groove ball bearings to support the worm and worm gear shaft to ensure smooth rotation and rigidity.

[0185] (2) Static simulation (load ≥ 0.3 N·m) is performed using ANSYS to predict the strength and stability of the structure; a spatial orthogonal worm gear self-locking critical angle is calculated based on the Coulomb friction model to construct stable and reliable self-locking conditions and ensure self-locking performance; in this embodiment, static simulation is used to verify whether the stress and deformation of key components (such as worm gear tooth root, worm shaft, and bracket) are within the safe range under the maximum working load (simulating the torque received by the puncture arm when it is at the maximum lever arm position). The static simulation process includes: A. Material assignment: assigning correct material properties (such as the elastic modulus and yield strength of aluminum alloy) to each component; B. Constraints and loads: fixing the mounting surface of the base and applying a torque ≥ 0.3 N·m at the output end of the worm gear; C. Result analysis, including using stress cloud diagrams to check whether the maximum equivalent stress is lower than the yield strength of the material, and the safety factor is generally required to be greater than 1.5; using deformation cloud diagrams to check the maximum deformation to ensure that it is much smaller than the accuracy requirements of angle adjustment (such as micrometer level), as excessive deformation will affect the transmission accuracy and meshing state.

[0186] (3) An incremental magnetic encoder is used to monitor the angular position and perform repeatability testing.

[0187] In this embodiment, the incremental magnetic encoder is typically installed at the tail end of the motor (not the output end) to measure the motor's rotation angle; the encoder reads the angular displacement of the motor shaft. The total reduction ratio of the system is obtained by multiplying the planetary reducer reduction ratio (e.g., 19:1) and the worm gear reduction ratio (e.g., 50:1), resulting in a total reduction ratio as high as 950:1. Assuming the encoder has 1000 lines (generating 4000 pulses per revolution), then for every degree the motor rotates, the output end (worm gear) rotates only 1° / 950≈0.00105° (i.e., 3.78 arcseconds). The output end angle resolution corresponding to each pulse is 360° / (950*4000)=0.0000947°≈0.34 arcseconds. This is an extremely high theoretical resolution, providing a foundation for achieving ultra-precise angle adjustment. The reasons for choosing a magnetic encoder include: strong anti-interference capability, insensitivity to environmental requirements (e.g., dust, slight oil contamination), long lifespan, and suitability for medical equipment.

[0188] (4) A miniature mechanical position sensor is used to zero the position after each angle adjustment, avoiding the accumulation of cumulative errors and thus achieving the functions of absolute position reference and cumulative error elimination. Furthermore, since incremental encoders cannot provide absolute position information upon power-up, and long-term operation may result in pulse loss (albeit minimal) leading to error accumulation, an origin sensor is set at the mechanical travel limit of each rotational degree of freedom (yaw and pitch axes). Miniature mechanical position sensors include: miniature limit switches (mechanical contact type, low cost, reliable); or Hall effect sensors (non-contact type, detecting magnets mounted on the rotating shaft, extremely long lifespan); or photoelectric sensors (through-beam or reflective type, high accuracy). The "zeroing" process includes: after the system starts or completes an angle adjustment, the controller drives the puncture arm to move slowly towards a preset mechanical origin (such as 0 degrees pitch or 0 degrees yaw); when the origin sensor in that direction is triggered, the motor stops immediately; the controller forces the encoder's count value to be set to the absolute "zero" coordinate; this operation clears all possible accumulated errors and ensures that each angle adjustment starts from a known, precise absolute reference.

[0189] Also includes, for example Figure 9 (a) and Figure 9 (b) shows the needle clamp 3 and its assembly structure. The needle clamp 3 includes a needle clamp body 31, which is made of medical polycarbonate PC-MR material and is injection molded.

[0190] Also includes, for example Figure 10 (a) and Figure 10(b) shows the needle guide 4 and its assembly structure. The needle guide 4 includes a needle guide body 41, which is made of medical polyethylene resin G232BT(Q281) and formed by injection molding. The material identification of G232BT(Q281) includes the enterprise's custom grade and the corresponding national standard performance level.

[0191] Based on engineering principles, 3D models of the needle clamp and needle guide were created using SolidWorks to demonstrate the model's geometric dimensions, injection molding performance, and functional requirements. Static simulations were performed using ANSYS to predict the structure's strength and stability.

[0192] A continuous stability assurance system for the puncture mechanism 5; the core objective of this system is to detect, suppress, and even eliminate any shaking or vibration that may occur during the operation of the puncture mechanism. This shaking may originate from uneven motor movement, gaps in the transmission mechanism, or external interference. In this embodiment, to ensure the continuous stability of the puncture mechanism's operation, an image acquisition device can be used to acquire real-time motion images of the puncture arm mechanism, and a first algorithm is used to achieve vision-based shaking state recognition and quantification; and a second algorithm is used to achieve motion smoothing control and risk warning based on quintic polynomial interpolation; wherein the vision-based shaking state recognition and quantification includes: identifying the shaking state based on the analysis of the real-time motion images and accurately quantifying the shaking amplitude; the motion smoothing control and risk warning based on quintic polynomial interpolation includes: planning the acceleration curve through the quintic polynomial interpolation algorithm to achieve smooth control of the motion process, while establishing a risk warning mechanism, through... Figure 11 The position command closed-loop control system, as shown in the diagram, corrects and calibrates the movement position in real time to ensure that the puncture mechanism reaches the target position; through... Figure 12 The feedforward and feedback PID composite algorithm shown can effectively avoid operational risks caused by jitter.

[0193] As a preferred embodiment, the workflow of the puncture mechanism continuous stability assurance system (5) can be clearly divided into two main stages: visual-based jitter state recognition and quantification, and motion smoothing control and risk warning based on fifth-order polynomial interpolation. The corresponding first algorithm and second algorithm are as follows:

[0194] (I) First Algorithm: Jitter State Recognition and Quantization Based on Image Acquisition

[0195] This is a process of non-contact, high-precision motion analysis using computer vision.

[0196] 1. Image acquisition equipment configuration:

[0197] (1) Hardware selection: A high-speed miniature CMOS image sensor is adopted. Key selection parameters include:

[0198] Frame rate: At least 200 fps (frames per second). A high frame rate is a prerequisite for capturing high-frequency jitter. Assuming the jitter frequency is between 10-50Hz, according to the sampling theorem (Nyquist frequency), the frame rate needs to be at least 100fps, and 200fps or higher can provide more accurate waveform reconstruction.

[0199] Resolution: 1280x720 or higher. High resolution helps achieve sub-pixel positioning accuracy.

[0200] Global shutter: superior to rolling shutter. Global shutter ensures that the entire image is exposed at the same moment, avoiding distortion when shooting fast-moving objects.

[0201] Installation location: Secure it to the device base, ensuring it is stationary relative to the motion platform of the puncture arm. Aim the lens at the component to be tested on the puncture arm mechanism, such as the integrated slider or a specially designed high-contrast marker.

[0202] 2. Jitter State Recognition and Quantization Algorithm Flow:

[0203] (1) Step 1: Marker detection and tracking, used to accurately find the center coordinates of pre-marked markers in each frame of the image. The algorithm flow includes:

[0204] (A) ROI (Region of Interest) setting: In the first frame, manually or automatically set a region containing marker points to reduce the amount of computation in subsequent processing.

[0205] (B) Image preprocessing: The image within the ROI is converted to grayscale, Gaussian filtered (denoising), and contrast enhanced to improve the signal-to-noise ratio.

[0206] (C) Feature Extraction: Subpixel-level corner detection algorithms (such as cv::cornerSubPix in OpenCV) or template matching algorithms are used to calculate the image coordinates (u_t, v_t) of the center of the marker point, where t is the current timestamp. Subpixel algorithms can improve the positioning accuracy to one-tenth or even one-hundredth of a pixel.

[0207] (2) Step Two: Motion Data Conversion and Filtering, used to convert the image coordinate sequence into a physical displacement sequence and separate the useful signal from the noise. The algorithm flow includes:

[0208] (A) Camera Calibration: The camera is calibrated beforehand using a calibration board to obtain intrinsic parameters (focal length, principal point) and extrinsic parameters (position relative to the puncture arm). Through perspective transformation, the image coordinates (u_t, v_t) of the marker point are converted into actual displacements (x_t, y_t) (unit: mm) in the two-dimensional measurement plane. This is a simplified model, assuming that the marker point mainly moves within the two-dimensional plane.

[0209] (B) Data Filtering: The raw displacement data contains high-frequency electronic noise. A low-pass digital filter (such as a Butterworth or Kalman filter) is used for smoothing. The filter's cutoff frequency needs to be set higher than the expected normal motion frequency but lower than the jitter frequency to ensure that the true jitter signal is preserved while filtering out noise.

[0210] (3) Step 3: Jitter feature extraction and quantization, used to extract key indicators representing the degree of jitter from the smoothed displacement data. The algorithm flow includes:

[0211] (A) Ideal trajectory generation: Based on the motion control command, a theoretically ideal displacement-time curve s_ideal(t) is generated. For uniform puncture, this is a slanted line; for variable speed motion, it is a planned curve given by the controller.

[0212] (B) Jitter Error Calculation: Calculate the difference between the actual displacement s_actual(t) and the ideal displacement s_ideal(t) to obtain the jitter error e(t) = s_actual(t) - s_ideal(t). The e(t) sequence is the direct manifestation of jitter.

[0213] (C) Calculation of quantitative indicators:

[0214] Jitter amplitude: Directly calculate the peak value or root mean square (RMS) of the error sequence e(t). The RMS value better reflects the overall energy level of the jitter. RMS = sqrt((1 / N)*Σ[e(t)]) 2 ]).

[0215] Jitter frequency: Performing a Fast Fourier Transform (FFT) on the error sequence e(t) converts the time-domain signal to the frequency domain. Analyzing the spectrum can identify the main frequency components of the jitter. This is crucial for diagnosing jitter sources (such as the resonant frequency of a specific motor).

[0216] Jitter Acceleration: Perform a second numerical differential on the displacement data s_actual(t) (calculate acceleration) and analyze its changes. Sudden changes in acceleration are the direct cause of jitter and impact forces.

[0217] At this point, the system has completed the "precise quantification" of jitter, transforming the indescribable "unstable feeling" into specific and measurable numerical indicators (such as "jitter RMS value is 15 micrometers, main frequency is 25Hz").

[0218] (II) Second Algorithm: Fifth-order Polynomial Interpolation Smoothing Control and Risk Warning

[0219] The core of this stage is to use the quantization results from the first stage to optimize the motor's motion commands through advanced motion planning algorithms, thereby suppressing jitter at its source.

[0220] 1. Quintic Spline Algorithm: Traditional motion control methods, such as trapezoidal velocity curves or S-curves, exhibit abrupt changes in acceleration at the start and end points (i.e., the jerk acceleration is infinite). This sudden change in acceleration impacts the mechanical system and is a major cause of vibration. Quintic spline interpolation is used to plan the displacement curve from the start to the end point. Its extreme smoothness is achieved because it can simultaneously constrain displacement, velocity, acceleration, and jerk acceleration. The algorithm flow includes:

[0221] (1) Setting boundary conditions: For a motion segment from time t=0 to t=T, six boundary conditions need to be satisfied, which requires a fifth-degree polynomial:

[0222] s(0) = 0 (starting position)

[0223] s(T) = S (target position)

[0224] v(0) = v0 (initial velocity)

[0225] v(T) = vT (final velocity)

[0226] a(0) = a0 (Initial acceleration)

[0227] a(T) = aT (final acceleration)

[0228] Typically, to ensure a smooth start and end, we set v0=vT=0 and a0=aT=0.

[0229] (2) Construct a fifth-degree polynomial:

[0230] The displacement equation is set as: s(t) = a0 + a1*t + a2*t 2 +a3*t 3 +a4*t 4 +a5*t 5 ;

[0231] Differentiating these equations yields the velocity v(t) and acceleration a(t); substituting the six boundary conditions into the system of equations, we can solve for the six unique coefficients a0 to a5.

[0232] 2. Real-time trajectory generation: In each control cycle (e.g., 1ms), the controller calculates the desired position s(t) corresponding to the current time t based on the calculated polynomial coefficients, and sends it as a command to the motor driver. Since the acceleration a(t) is a continuously changing cubic curve and the jerk j(t) is a continuously changing quadratic curve, rigid impact is completely eliminated, resulting in extremely smooth motion.

[0233] 3. Combination with jitter feedback – Adaptive smoothing control:

[0234] The system does not always use a fixed fifth-order polynomial curve. It adaptively adjusts based on the jitter identified in the first stage:

[0235] (1) When the jitter amplitude is detected to exceed the threshold, the system will actively extend the planned motion time T. Because for the same displacement S, the longer the time T, the smaller the maximum acceleration and velocity required, and the smoother the motion will be. This is equivalent to providing the system with more "relaxed" conditions to complete the action, effectively suppressing jitter.

[0236] (2) Frequency-based suppression: If FFT analysis finds that jitter occurs continuously at a certain frequency (e.g., 25Hz), a notch filter for that frequency can be added to the pre-filter of the motion planner to weaken the excitation at that frequency in advance at the instruction level.

[0237] 4. Risk warning mechanism: This is an independent decision-making layer based on safety thresholds, including:

[0238] (1) Threshold setting: Set multiple levels of security thresholds. For example:

[0239] Warning threshold (yellow): Jitter RMS > 20μm. The system logs the message and displays a notification in the UI, but does not shut down.

[0240] Danger threshold (red): Jitter RMS > 50 μm or a sudden and sharp increase in the peak displacement error. This indicates possible mechanical jamming or severe interference.

[0241] (2) Implementing early warning actions, including:

[0242] Real-time alarm: Visual and audible warnings are displayed on the device's screen or indicator lights to alert the operator;

[0243] Automatic deceleration or pause: The system automatically switches to a more conservative (slower) fifth-order polynomial trajectory, or directly initiates a smooth emergency stop (also using a fifth-order polynomial planning stop curve to avoid sudden stop impact).

[0244] Puncture prohibition: In extreme cases, the system will lock the motor, prohibit the puncture action from continuing, and prompt that equipment maintenance is required, thereby "timely avoiding operational risks caused by vibration".

[0245] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. A machine arm based on a spatially orthogonal worm and gear composite transmission architecture, characterized by, A handheld intelligent vascular puncture system comprises: A puncture arm mechanism (1) comprising a linear rectangular multi-surface guide rail (11), a double-head rectangular lead screw (12), an integrated slider screw nut (13), a precision planetary reducer (14), and a hollow cup motor (15), which is used to receive instructions from a control system, accurately and smoothly convert the rotary motion of the motor into linear puncture needle advancing and retracting motion, and feedback the puncture depth in real time; the puncture arm mechanism (1) comprises a driving device and a puncture system architecture; wherein the driving device is composed of a small-volume high-power-density hollow cup motor, a planetary reducer, and a double-head rectangular lead screw; the puncture system architecture is composed of an integrated slider screw nut and a linear rectangular multi-surface guide rail (11), which is a transmission and guide architecture for converting the rotary motion of the double-head rectangular lead screw into linear motion and bearing all radial forces and moments generated during the puncture process, ensuring the accuracy and stability of the motion trajectory; A puncture arm angle adjustment mechanism (2) comprising a first spatial orthogonal worm (21), a second spatial orthogonal worm wheel (22), a worm and worm wheel housing (23), a puncture arm angle adjustment mechanism planetary reducer (24), a puncture arm angle adjustment mechanism hollow cup motor (25), and a side wall guide structure (26), which is used to accurately and stably adjust and lock the attitude angle of the puncture arm in space based on the adjustment of at least two degrees of freedom of the pitch angle and the yaw angle; wherein the puncture arm angle adjustment mechanism (2) adopts a small-volume high-power-density hollow cup motor, a precision planetary reducer, and a self-locking spatial orthogonal worm and worm wheel composite transmission architecture; A needle holder (3) comprising a needle holder main body (31) made of medical polycarbonate PC-MR material and injection molded; A needle guide (4) comprising a needle guide main body (41) made of medical polyethylene resin G232BT(Q281) material and injection molded; A puncture mechanism continuous stability guarantee system (5) that uses image acquisition equipment to collect real-time motion images of the puncture arm mechanism, and realizes visual-based jitter state recognition and quantification based on a first algorithm; and realizes motion smoothing control and risk warning based on a quintic polynomial interpolation based on a second algorithm; wherein the visual-based jitter state recognition and quantification includes identifying the jitter state based on analysis of the real-time motion images and accurately quantifying the jitter amplitude; wherein the motion smoothing control and risk warning based on the quintic polynomial interpolation includes planning an acceleration curve through a quintic polynomial interpolation algorithm to achieve smooth control of the motion process, while establishing a risk warning mechanism to real-time correct and calibrate the motion position through a position instruction closed-loop control system to ensure that the puncture mechanism reaches the target position; and avoiding operation risks caused by jitter in time through a feedforward and feedback PID composite algorithm.

2. A machine arm based on spatial orthogonal worm and wheel composite transmission architecture according to claim 1, characterized in that, The hollow cup motor is a brushless direct current hollow cup motor, and the planetary reducer is a precise miniature planetary gear reducer, which is used for increasing torque and reducing speed. The planetary reducer is directly connected with the hollow cup motor through a standard flange interface to form a compact "motor + reducer" module. The planetary reducer is directly fixed with the front end cover of the hollow cup motor through a stop and a screw. The input shaft of the planetary reducer is connected with the motor shaft of the hollow cup motor through a tight screw or an embossing cooperation. The double-headed rectangular lead screw is a precisely ground double-headed rectangular threaded lead screw, which is used for motion conversion. The output shaft of the planetary reducer is internally processed with a connecting hole. The input end of the double-headed rectangular lead screw is processed into a light shaft or a shaft with a key groove, and is rigidly connected with the output shaft of the planetary reducer through a high-precision jack or an elastic coupling. The shaft shoulder of the double-headed rectangular lead screw is positioned by the inner ring of the bearing of the output end of the planetary reducer.

3. A machine arm based on spatial orthogonal worm and wheel composite transmission architecture according to claim 2, characterized in that, In the puncture system architecture, the integrated slider lead screw nut serves as a motion executor and is composed of an integrated slider and a lead screw nut. The integrated slider is a cuboid or cubic metal block. A threaded hole precisely matched with the double-headed rectangular lead screw is processed in the center of the integrated slider as the lead screw nut. A slider slot or a mounting hole matched with the linear rectangular multi-surface pair guide rail (11) is processed on the bottom or side surface of the integrated slider. The linear rectangular multi-surface pair guide rail (11) of the puncture system architecture is a square linear sliding guide rail or a double-prism guide rail, which is used as a guide and force bearing mechanism to form a surface contact guide system.

4. A machine arm based on spatial orthogonal worm and wheel composite transmission architecture according to claim 3, characterized in that, The linear rectangular multi-surface pair guide rail (11) includes a guide rail and a guide rail slot corresponding to the slider slot. The guide rail is fixed on the body or base of the puncture mechanism in parallel, which provides an accurate linear reference. The guide rail slot includes a rectangular slot precisely matched with the guide rail and processed on the integrated slider. The rectangular slot is a multi-surface pair in surface contact form. The integrated slider is arranged on the two guide rails through the multi-surface pair.

5. A machine arm based on spatial orthogonal worm and wheel composite transmission architecture according to claim 4, characterized in that, The design process of the puncture arm mechanism (1) includes: (1) According to the engineering principle, the 3D model of the puncture mechanism is established by solidworks, and the model geometry, manufacturability and functional requirements are demonstrated. (2) The statics simulation is performed by ANSYS to predict the strength and stability performance of the structure. (3) The incremental magnetic encoder is used to monitor the puncture depth based on reading the number of rotation and angle of the motor by using the principle of converting the continuity of mechanical motion into the discreteness of electrical signals. The incremental magnetic encoder is installed at the tail of the hollow cup motor opposite to the reducer. The hollow cup motor, the planetary reducer, the double-headed rectangular threaded lead screw and the incremental magnetic encoder form a coaxial series connection.

6. A machine arm based on spatial orthogonal worm and wheel composite transmission architecture according to claim 5, characterized in that, The worm shaft and the worm wheel shaft of the space orthogonal worm wheel and worm are staggered at 90 degrees in three-dimensional space and are not in the same plane; for the freedom adjustment of the yaw angle, the horizontal angle adjustment is realized by adjusting the yaw shaft; for the freedom adjustment of the pitch angle, the vertical pitch angle adjustment is realized by adjusting the pitch shaft, so that the end of the puncture arm is positioned at any required angle in space by controlling the coordinated movement of the two motors; The precise planetary reducer is a micro low-backlash planetary gear reducer, which is used for primary reduction and torque increase, and directly constitutes a compact "motor reducer integrated module" with the motor through a standard flange, so that the primary reduction and torque increase are performed between the motor and the worm wheel and worm pair.

7. A machine arm based on spatial orthogonal worm and wheel composite transmission architecture according to claim 6, characterized in that, The self-locking space orthogonal worm wheel and worm is a core transmission and self-locking function component, which comprises: A single-head worm, one end of which is connected to the output shaft of the precise planetary reducer through a flexible coupling or a precise jackscrew; A split worm wheel, which has an involute or ZA type tooth profile accurately matched with the single-head worm; The self-locking condition is to calculate the self-locking critical angle of the space orthogonal worm wheel and worm based on the Coulomb friction model, and the critical condition of self-locking is that the lead angle γ of the worm is less than or equal to the equivalent friction angle ρ of the worm wheel and worm pair; wherein the calculation formula of the lead angle γ is as shown in formula (1): γ = arctan (lead / (π * worm division circle diameter)) = arctan (modulus * number of heads / division circle diameter) (1); The calculation formula of the equivalent friction angle ρ is as shown in formula (2): ρ = arctan (μ) (2); Wherein μ is the friction coefficient, which is determined by the material pairing and lubrication condition.

8. A machine arm based on spatial orthogonal worm and wheel composite transmission architecture according to claim 7, characterized in that, The design process of the puncture arm angle adjustment mechanism (2) includes: (1) According to the engineering principle, the 3D model of the angle adjustment mechanism is modeled through solidworks, and the model geometry, manufacturability and functional requirements are demonstrated; including: all parts are modeled in detail; interference and gap check is carried out to ensure that the meshing gap of the worm wheel and worm is appropriate, and all moving parts have no collision; quality attribute analysis is carried out to optimize the weight distribution and ensure the hand balance feeling; and the bearing seat is designed, and the micro deep groove ball bearing is selected to support the worm and worm wheel shaft to ensure smooth rotation and rigidity; all parts include: bracket, bearing seat and shell; (2) Statics simulation is carried out through ANSYS to predict the strength and stability of the structure; the self-locking critical angle of the space orthogonal worm wheel and worm is calculated based on the Coulomb friction model, and the stable and reliable self-locking condition is constructed to ensure the self-locking performance; in this embodiment, statics simulation is used to simulate the torque received by the puncture arm when it is in the maximum force arm position, and to verify whether the stress and deformation of the worm wheel root, worm shaft and bracket are within the safety range under the maximum working load; the process of statics simulation includes: A. Material assignment: assign correct material properties to each component; B. Constraints and loads: fix the base mounting surface and apply a ≥0.3 N·m torque to the output end of the worm wheel. C. Result analysis, including checking whether the maximum equivalent stress is lower than the yield strength of the material by using stress contour, and the safety factor is generally required to be greater than 1.5; checking the maximum deformation by using deformation contour to ensure that it is much smaller than the accuracy requirement of angle adjustment; (3) An incremental magnetic encoder is used to monitor the angle position and perform repeated positioning accuracy test; the incremental magnetic encoder is usually installed at the non-output end of the tail of the motor and is used to measure the rotation angle of the motor; the encoder reads the angular displacement of the motor shaft; (4) A micro-mechanical position detection sensor is used to perform zeroing after each angle adjustment to avoid the accumulation of accumulated errors, thereby achieving the functions of absolute position reference and accumulated error elimination; the micro-mechanical position detection sensor includes a micro-limit switch, a Hall sensor or a photoelectric sensor; the zeroing process includes: after the system starts or completes an angle adjustment, the controller drives the puncture arm to slowly move in a certain preset mechanical origin direction; when the origin sensor in this direction is triggered, the motor immediately stops; the controller forcibly sets the encoder count value at this time as the absolute zero coordinate.

9. A machine arm based on spatial orthogonal worm and wheel composite transmission architecture according to claim 8, characterized in that, The vision-based jitter state recognition and quantification based on the first algorithm comprises: S1, marker detection and tracking, which is used to accurately find the center coordinates of the marker in each frame of image, including: Setting ROI (region of interest) setting, including: manually or automatically setting a region containing the marker in the first frame; Preprocessing the image, including: grayscale, Gaussian filtering and contrast enhancement of the image in the ROI to improve the signal-to-noise ratio; Feature extraction: using a sub-pixel level corner detection algorithm or a template matching algorithm to calculate the image coordinates of the marker center, where t is the current timestamp; S2, motion data conversion and filtering, which is used to convert the image coordinate sequence into a physical world displacement sequence and separate the useful signal and noise, including: Camera calibration, including: calibrating the camera through a calibration board to obtain the intrinsic and extrinsic parameters; converting the image coordinates of the marker into the actual displacement in the two-dimensional measurement plane through perspective transformation; Data filtering, including: smoothing by using a low-pass digital filter; S3, jitter feature extraction and quantification, which is used to extract key indicators representing the degree of jitter from the smoothed displacement data, including: Generating an ideal trajectory, including: generating a theoretical ideal displacement-time curve according to the motion control instruction, which is a diagonal line for uniform puncture and a planning curve given by the controller for variable speed motion; Calculating the jitter error, including: calculating the difference between the actual displacement and the ideal displacement to obtain the jitter error e(t), and the e(t) sequence is a direct manifestation of the jitter; Calculating the quantification index, including: Calculating the jitter amplitude: directly calculating the peak value or root mean square value of the error sequence e(t); Calculating the jitter frequency: performing fast Fourier transform on the error sequence e(t) to convert the time domain signal to the frequency domain, and analyzing the frequency spectrum to obtain the main frequency component of the jitter; Calculate the jerk acceleration: the displacement data is twice the numerical differential calculation of acceleration, and its change is analyzed, where the sudden acceleration change is the direct cause of the generation of the jitter and impact force.

10. A machine arm based on spatial orthogonal worm and wheel composite transmission architecture according to claim 9, characterized in that, The motion smoothing control and risk early warning based on the second algorithm includes: S1, performing quintic polynomial interpolation, including: (1) Set boundary conditions: for a motion segment from time t=0 to t=T, 6 boundary conditions need to be met, as follows: s(0) = 0 (starting position) s(T) = S (target position) v(0) = v0 (starting speed) v(T) = vT (end speed) a(0) = a0 (starting acceleration) a(T) = aT (end acceleration) In order to smooth the start and end, v0=vT=0; a0=aT=0; (2) Construct a quintic polynomial: The displacement equation is set as: s(t) = a0 + a1 *t + a2 *t 2 +a3 *t 3 +a4 *t 4 +a5 *t 5 ; Derive the velocity v(t) and acceleration a(t); Substitute the 6 boundary conditions into the equation set to solve the unique 6 coefficients a0 to a5; S2, generate real-time trajectory, including: the controller calculates the expected position s(t) corresponding to the current time t according to the calculated polynomial coefficients at each control period, and sends it to the motor driver as an instruction; S3, adaptive smoothing control based on the combination of jitter feedback, including: (1) When the jitter amplitude is identified to exceed the threshold, the planned motion time T is actively extended; (2) Implement frequency-based suppression, including: if FFT analysis finds that the jitter persists at a certain frequency, add a notch filter for that frequency in the pre-filter of the motion planner to weaken the excitation of that frequency in the instruction level in advance.

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