A lightweight slurry material extrusion device and its control method

Abstract

This invention provides a lightweight extrusion device for slurry-like materials and its control method. The device includes a servo motor, a screw, a piston, a barrel, a front cover of the barrel, a rear cover of the barrel, and a discharge port. The servo motor drives the screw, which in turn drives the piston to extrude the slurry. The barrel has a detachable structure for quick assembly and maintenance. The system is equipped with motor sensors, pressure sensors, and discharge port flow rate monitoring sensors to construct a multi-state closed-loop control mechanism. Combined with a feedforward-feedback composite control algorithm, it achieves precise management of the entire process of startup, operation, and shutdown. This device has a simple structure and is lightweight, making it suitable for aerial platforms such as drones. It features high control precision, stable material output, adaptive adjustment, and safety protection functions, and is applicable to the 3D printing of various slurry-like materials such as clay, pulp, and low-viscosity cement slurry.

Description

Technical Field

[0001] This invention relates to the technical field of printing slurry materials, and more particularly to a lightweight slurry material extrusion device and its control method. Background Technology

[0002] In current 3D printing technology, the extrusion of slurry materials such as clay mainly employs either pneumatic or electric extrusion methods. Pneumatic extrusion devices typically use an air compressor to pressurize the rear of the barrel through an air pipe, pushing a piston forward to extrude the slurry. Electric extrusion devices, on the other hand, use a motor located at the rear of the barrel to drive a screw forward, pushing the piston to achieve extrusion. These traditional extrusion devices are widely used in terrestrial 3D printing equipment, but they generally suffer from large size, heavy weight, and complex structure, making them unsuitable for installation on aerial platforms such as drones.

[0003] Furthermore, the control system of this type of device is complex, making it difficult to achieve high-precision material discharge control. Due to the characteristics of mud-like materials, such as large fluctuations in humidity, viscosity, and density, if a rotating screw feeding device is not installed at the nozzle end, problems such as unstable material discharge, slow start-up response, and dripping are likely to occur, thus limiting its promotion in application scenarios such as aerial additive manufacturing, which have high requirements for lightweighting and precise control.

[0004] Traditional open-loop control faces three major challenges in mud extrusion: asynchronous start-up, lag in speed response, and dripping during stop. Summary of the Invention

[0005] The purpose of this invention is to provide a mud-based material extrusion device and its control method suitable for aerial 3D printing (drone-mounted) with features such as lightweight, simple structure, stable output, and high control precision.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A lightweight slurry material extrusion device includes an extrusion mechanism, a sensor unit, and an intelligent control system;

[0008] The extrusion mechanism includes a screw, a flange nut, a servo motor, a rear cover of the barrel, a piston, a barrel, a front cover of the barrel, and a discharge port. The screw is connected to the output shaft of the servo motor via the flange nut, and the servo motor drives the screw to move linearly. One end of the screw passes through the rear cover of the barrel and is connected to a push block. The push block drives the piston to reciprocate within the barrel, extruding the slurry. The front cover of the barrel is installed at the front end of the barrel, and a discharge port is located at the center of the front cover, communicating with the interior of the barrel for outputting slurry.

[0009] The sensor unit includes a motor sensor, a pressure sensor, and a discharge port flow rate monitoring sensor;

[0010] The motor sensor is installed on the servo motor and is used to collect the motor speed, position and direction, calculate the position of the screw or piston and calculate the amount of remaining mud.

[0011] The pressure sensor is installed on the front cover of the barrel and is used to detect the extrusion pressure;

[0012] The discharge port flow rate monitoring sensor is installed on the discharge pipe connected to the discharge port and is used to detect the actual extrusion speed.

[0013] The external control system is used to send the desired extrusion speed, start and stop commands to the mud extrusion control system, and to receive the waiting, preparation and error status signals output by the signal monitoring module.

[0014] The mud extrusion control system includes a signal monitoring module and a motor control module;

[0015] The signal monitoring module is connected to the sensor unit and is used to collect and preprocess the speed, torque, and position signals of the servo motor and the actual flow rate signal at the discharge port, calculate the amount of remaining mud in real time, and determine the operating status.

[0016] The motor control module is connected to the servo motor and is used to execute the feedforward-feedback composite control algorithm and the stop-pullback algorithm according to the instructions of the external control system and the feedback of the signal monitoring module, generate motor drive commands, and realize closed-loop control of the extrusion process.

[0017] Preferably, the intelligent control system adopts a multi-state management mechanism, including a waiting extrusion state, a ready state, a printing state, a stopped state, and an error reporting state; each state is triggered according to sensor signals.

[0018] Preferably, in the waiting-for-extrusion state: upon receiving a start command from an external control system to send to the mud extrusion control system, the servo motor rotates at a preset initial speed and continuously monitors the discharge outlet flow rate measured by the discharge outlet flow rate monitoring sensor to prevent the print head from moving prematurely before material is discharged.

[0019] The ready state: When the actual flow rate continuously exceeds the threshold, the servo motor speed is maintained and a signal that the mud is ready is sent to the external control system to achieve synchronous start-up;

[0020] The printing state: When the main system enters the printing process, a feedforward-feedback composite control algorithm is executed to dynamically adjust the motor speed according to the deviation between the expected extrusion speed and the actual speed, thereby reducing response lag and eliminating steady-state error;

[0021] The stopped state: When a stop command is received, the required amount of backflow is calculated based on the pressure value measured by the pressure sensor and the flow rate feedback. The screw is driven to move in the opposite direction to release the pressure of the mud in the barrel, so that the mud at the outlet stops immediately, thereby avoiding mud accumulation and leakage at the outlet.

[0022] The error reporting status is as follows: when the motor torque exceeds the preset threshold, an emergency retraction operation is immediately performed to prevent damage to the device due to material blockage or overload.

[0023] Preferably, the printing state employs a feedforward-feedback composite control algorithm, and its target rotational speed is given by the following formula:

[0024]

[0025] Feedforward control terms:

[0026]

[0027] in, For the desired extrusion speed, The screw pitch is... This refers to the motor-screw transmission ratio. For adaptive coefficients, To accelerate the compensation coefficient, For the desired acceleration;

[0028] Feedback control items:

[0029]

[0030] in, It is a proportional-integral-derivative controller. For the desired extrusion speed, The actual velocity measured by the flow rate monitoring sensor at the discharge port.

[0031] Preferably, the adaptive coefficient is related to the volume ratio of the remaining mud, which is calculated by the following formula:

[0032]

[0033] in, This represents the volume ratio of the remaining mud. For the remaining volume, This represents the initial filling volume of the barrel;

[0034]

[0035] Accumulate position information for the motor sensor. The reduction ratio, The diameter of the screw. The screw pitch is... Let be the cross-sectional area of ​​the screw.

[0036] Preferably, the execution of the stop state is based on a composite stop algorithm of pressure sensing and flow rate feedback, including feedforward retracement amount and feedback retracement amount;

[0037] The feedforward pullback amount:

[0038]

[0039] in, This is the pressure pullback coefficient. The real-time pressure captured by the pressure sensor. This is a material level adaptive function;

[0040] The feedback pullback amount:

[0041]

[0042] in, For speed feedback gain, For actual speed measurement, For speed integral feedback gain, The time integral of the extrusion speed;

[0043] The motor control module according to Generate reverse drive commands to quickly stop extrusion and prevent dripping.

[0044] Preferably, the material level adaptive function adopts one of the following two types:

[0045] Linear functions: ;

[0046] in, This is a material level adaptive function. This represents the volume ratio of the remaining mud. It is a linear proportionality coefficient. The linear bias coefficient;

[0047] Nonlinear functions: ;

[0048] in, This is a material level adaptive function. These are nonlinear coefficients. This is the second offset of the remaining volume ratio relative to the full-load state, ensuring that the correction amount is always positive.

[0049] The present invention also provides a control method for a lightweight slurry material extrusion device, comprising the following steps:

[0050] Step S1: The external control system sends the desired extrusion speed and start / stop commands;

[0051] Step S2: The servo motor drives the screw to move linearly under the monitoring of the motor sensor. The screw drives the piston to move along the axial direction of the barrel through the push block, thereby pressurizing and extruding the mud. The mud is discharged through the front cover of the barrel and the discharge port.

[0052] Step S3: The signal monitoring module collects data from the motor sensor, pressure sensor, and discharge outlet flow rate monitoring sensor in real time, and calculates the remaining mud volume and the actual discharge speed.

[0053] Step S4: The motor control module determines its operating status based on the acquired signals.

[0054] While waiting for extrusion, the drive screw moves at an initial speed until a stable flow rate is detected;

[0055] In the ready state: when the actual flow rate continues to exceed the threshold, the rotation speed of the servo motor (3) is maintained and a mud material ready signal is sent to the external control system to achieve synchronous start-up;

[0056] During printing, a feedforward-feedback composite control algorithm is executed to adjust the speed of the servo motor based on the deviation between the desired speed and the actual speed, thereby achieving precise control of the output amount.

[0057] In the stopped state, the required amount of backflow is calculated by combining the pressure sensor and flow rate feedback, and the screw is driven to move in the opposite direction to release the pressure inside the barrel and prevent leakage from the outlet.

[0058] In an error state, if the pressure or torque exceeds the threshold, the screw will be immediately driven to reverse and retract rapidly to protect the device.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] High control precision and stable output: This invention constructs an innovative multi-state closed-loop control system and introduces a feedforward-feedback composite control algorithm to achieve real-time adjustment of the mud discharge speed. It effectively solves the problems of asynchronous start-up, speed lag and dripping during extrusion in traditional open-loop control, thereby significantly improving printing quality and ensuring output stability.

[0061] Simple structure and lightweight: By eliminating the traditional end-rotating feeding structure and adopting a lightweight and modular design, this invention simplifies the overall structure and significantly reduces the weight, making it particularly suitable for load applications on aerial platforms such as drones and robotic arms.

[0062] High degree of collaboration and intelligence: This invention achieves intelligent linkage control of the entire printing process by setting status signals (READY / WAITING, etc.) and collaborating with the main printing system. At the same time, it combines predictive (feedforward), adaptive (parameter self-adaptation) and feedback control capabilities to ensure high precision and high synchronization of the printing process.

[0063] High reliability and safety: By introducing a torque-based real-time monitoring and protection mechanism, this invention enables emergency back-pull function in case of overload or material blockage, thereby significantly improving the safety and reliability of the device.

[0064] Easy to carry and maintain: Through modular and miniaturized structural design, this invention achieves portability and easy maintenance of the device, facilitating quick disassembly, material replacement and cleaning.

[0065] High adaptability: By considering the compressibility, viscoelasticity and dynamic changes in residual material of slurry materials in the control algorithm, this invention achieves adaptive extrusion control for various slurry materials such as clay, pulp, and low-viscosity cement slurry, ensuring stable application results under different working conditions.

[0066] In summary, this invention, through innovative structural simplification and lightweight design, combined with a multi-state closed-loop control system and a feedforward-feedback composite control algorithm, achieves high-precision, stable, and intelligent control of slurry materials during the extrusion process. It not only effectively solves the problems of asynchronous start-up, lag in speed response, and dripping during stop that exist in traditional open-loop control, but also has the advantages of safety, reliability, strong adaptability, portability, and ease of maintenance. Attached Figure Description

[0067] Figure 1 A three-dimensional structural schematic diagram of a lightweight slurry material extrusion device provided for an embodiment of the present invention;

[0068] Figure 2 An exploded view of a lightweight slurry material extrusion device provided as an embodiment of the present invention. Figure 1 ;

[0069] Figure 3 An exploded view of a lightweight slurry material extrusion device provided as an embodiment of the present invention. Figure 2 ;

[0070] Figure 4 An exploded view of a lightweight slurry material extrusion device provided as an embodiment of the present invention. Figure 3 ;

[0071] Figure 5 A cross-sectional view of a lightweight slurry material extrusion device provided for an embodiment of the present invention;

[0072] Figure 6 A schematic diagram showing the location of the sensing unit in a lightweight slurry material extrusion device provided for an embodiment of the present invention;

[0073] Figure 7 This is a schematic diagram illustrating the workflow of a control method for a lightweight slurry material extrusion device provided as an embodiment of the present invention.

[0074] The serial numbers in the diagram are as follows:

[0075] 1. Screw; 1-1. Push block; 2. Flange nut; 3. Servo motor; 4. Rear cover of barrel; 5. Piston; 6. Barrel; 7. Front cover of barrel; 8. Discharge port; 9. Motor sensor; 10. Pressure sensor; 11. Discharge port flow rate monitoring sensor. Detailed Implementation

[0076] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0077] like Figures 1 to 5 As shown, this embodiment provides a lightweight mud-like material extrusion device, which includes an extrusion mechanism, a sensor unit, and an intelligent control system.

[0078] The screw 1 has a diameter of 8mm, a pitch of 2mm, and is made of stainless steel. It is mounted on the output shaft of the servo motor 3 via the flange nut 2, and the servo motor 3 drives the screw 1 to move. One end of the screw 1 passes through the rear cover 4 of the barrel and is connected to the push block 1-1.

[0079] Servo motor 3, whose output shaft is connected to screw 1, drives screw 1 to perform linear motion. In this embodiment, servo motor 3 has a rated voltage of 24V, a rated current of 2.3A, a rated torque of 1.3Nm, a maximum torque of 2.7Nm, and an adjustable speed range. It connects to a computer control system via the CAN protocol to achieve precise control.

[0080] The barrel rear cover 4 is detachably connected to the rear end of the barrel 6 and provides support and sealing for the screw 1.

[0081] Piston 5 is disposed inside the barrel 6, with one side inserted into push block 1-1 and the other side tapered and positioned near the barrel front cover 7. Push block 1-1 is used to link piston 5 to move axially along the barrel 6, pushing the printing material. In this embodiment, piston 5 is made of high-performance nylon material and is magnetically connected to push block 1-1 at the end of screw 1. An O-ring seal is installed between piston 5 and the inner wall of barrel 6 to prevent leakage.

[0082] The material cylinder 6 is used to fill the printing material (clay, ceramic clay); the front cover 7 of the material cylinder is detachably connected to the front end of the material cylinder 6, and the discharge port 8 is connected to the shaft on the outside of the front cover 7 and communicates with the material cylinder 6 for outputting the extruded printing material. The discharge port 8 is equipped with a 10mm diameter standard pneumatic connector that is threaded to the front cover 7.

[0083] Furthermore, in this embodiment, the material is photosensitive resin (made by 3D printing), with a volume of 1000ml, a square cross-section (side length 80mm), and a length of 200mm. Its non-circular inner cavity can effectively prevent the piston 5 from rotating.

[0084] Furthermore, the rear cover 4 and front cover 7 of the material cylinder 6, which are connected to both ends respectively, are connected by a snap-on connection, which can be quickly opened without tools, facilitating the replacement of mud and cleaning. The snap-on connection to the drone uses an external hook, making disassembly and installation easy.

[0085] The servo motor 3 drives the piston 5 to move forward in a straight line through the screw 1, thereby achieving stable extrusion of the slurry in the barrel 6.

[0086] This embodiment simplifies the overall structure of the mud-pushing device by eliminating the complex rotating feeding screw structure at the discharge port 8 in the prior art, significantly reducing weight and facilitating drone mounting, thus achieving overall lightweighting.

[0087] Furthermore, all major components of the device in this embodiment (barrel 6, servo motor 3, screw 1, etc.) adopt a modular design, which facilitates quick disassembly, replacement and maintenance.

[0088] A sealed connection is achieved by using an O-ring seal between piston 5 and barrel 6; the discharge port 8 uses a standard pneumatic connector, which facilitates the connection of various print heads and enables the matching of multiple drones.

[0089] like Figure 6 As shown, the sensor unit includes a motor sensor 9, a pressure sensor 10, and a discharge outlet flow rate monitoring sensor 11.

[0090] Motor sensor 9 is installed on the output shaft of servo motor 3 to collect the position of screw 1 and calculate the amount of remaining mud.

[0091] Pressure sensor 10 is installed on the front cover 7 of the barrel and is used to detect extrusion pressure.

[0092] The discharge port flow rate monitoring sensor 11 is installed on the discharge pipe connected to the discharge port 8 and is used to detect the actual extrusion speed.

[0093] The intelligent control system is based on an embedded microcontroller (such as the STM32F4 series), equipped with a motor driver, signal conditioning circuit and communication interface (such as CAN), and runs the multi-state management mechanism described in this embodiment. The intelligent control system includes an external control system and a mud extrusion control system.

[0094] The external control system provides a human-machine interface, plans printing tasks, and sends instructions to the extrusion system at frequency a, including the desired extrusion speed, start and stop instructions, and receives waiting, ready and error status signals output by the signal monitoring module.

[0095] The mud extrusion control system includes a signal monitoring module and a motor control module.

[0096] The signal monitoring module is connected to the sensor unit to collect and preprocess the speed, torque, and position signals of the servo motor 3 and the actual flow rate signal at the discharge port, calculate the amount of remaining mud in real time, and determine the operating status.

[0097] The motor control module is connected to the servo motor 3 and includes a state machine and all control algorithms. It performs decision calculations and transmits execution instructions to the servo motor 3. Based on the instructions from the external control system and the feedback from the signal monitoring module, it executes the feedforward-feedback composite control algorithm and the stop-and-pullback algorithm to generate motor drive instructions and realize closed-loop control of the extrusion process.

[0098] Furthermore, in this embodiment, the intelligent control system adopts a multi-state management mechanism, including waiting to extrude, ready state, printing, stop, and error reporting state; each state is triggered according to sensor signals, and synchronous start-up, stable operation, precise stop, and abnormal protection are achieved through different control logics.

[0099] Waiting for extrusion (WAITING): When the external control system sends a start command to the mud extrusion control system, the servo motor 3 rotates at a preset initial speed and continuously monitors the discharge outlet flow rate measured by the discharge outlet flow rate monitoring sensor 11 to prevent the print head from moving prematurely before material is discharged.

[0100] Ready state: When the actual flow rate continues to exceed the threshold, the speed of servo motor 3 is maintained and a signal that the mud is ready is sent to the external control system to achieve synchronous start-up;

[0101] Printing: When the main system enters the printing process, a feedforward-feedback composite control algorithm is executed to dynamically adjust the motor speed according to the deviation between the desired extrusion speed and the actual speed. The feedforward control greatly reduces the response delay during speed change, and the feedback control eliminates steady-state error.

[0102] Stopping: A composite clay extrusion stopping algorithm based on pressure sensing and flow rate feedback. Upon receiving a stop command, the algorithm calculates the required retraction amount based on the pressure value measured by pressure sensor 10 and flow rate feedback. This drives screw 1 to reverse, releasing the pressure of the clay in barrel 6, causing the clay at outlet 8 to stop immediately, thus preventing clay accumulation and dripping at outlet 8. The core objective of the stopping algorithm is not to smoothly decelerate the motor to zero, but to rapidly release the elastic potential energy stored in the compressed clay through an active and precisely calculated reverse action (retraction) at the moment the command is issued, thereby immediately stopping the flow of clay at the outlet and forming a clean, clear break. This solution aims to solve the dripping problem of the extruder after a stop command is issued. Its core idea is to combine the speed of feedforward control with the precision of feedback control to form an efficient "predictive-corrective" dual-loop control strategy.

[0103] Error status (ERROR): When the motor torque exceeds the preset threshold, an emergency retraction operation is immediately performed to prevent damage to the device due to material blockage or overload.

[0104] During operation: The operator sets the printing task and desired speed on the intelligent control system. After the main system sends the Start command, the extrusion system enters the Waiting state, and the motor starts at a compensated speed to quickly discharge the sludge. When the actual flow rate is monitored... Once the target is met, the system enters the READY state and notifies the main system. The main system begins moving the printhead, and the extrusion system enters the PRINTING state, executing feedforward-feedback composite control to precisely maintain the extrusion speed. When the printed segment ends, the main system sends a Stop command, and the extrusion system enters the STOPPING state, executing a precise retraction algorithm to immediately cut off the material. Throughout the process, torque is continuously monitored; exceeding the limit triggers an ERROR protection mechanism.

[0105] The intelligent control system provided in this embodiment is an intelligent adaptive closed-loop control system that works in deep collaboration with the main printing system. Its core objective is to solve the three major problems faced by traditional open-loop control in clay extrusion: asynchronous startup, lagging speed response, and dripping during shutdown. We achieve precise control throughout the entire lifecycle, from extrusion startup and stable operation to shutdown, through a "feedforward-feedback" composite control algorithm and a multi-state management mechanism.

[0106] The printing process employs a feedforward-feedback composite control algorithm, and its target rotational speed is given by the following formula:

[0107]

[0108] Feedforward control terms:

[0109]

[0110] The desired extrusion speed;

[0111] The screw pitch;

[0112] This refers to the motor-screw transmission ratio;

[0113] This is an adaptive coefficient, related to the amount of remaining mud. The less mud there is, the slightly higher the coefficient becomes, in order to compensate for changes in system stiffness.

[0114] To accelerate the compensation coefficient, it was tuned experimentally to be positive during acceleration and negative during deceleration.

[0115] The desired acceleration is calculated as follows:

[0116]

[0117] in, For the latest expected extrusion rate, The expected extrusion speed in the previous moment, The time interval between two commands is calculated to form the system's predictive function, enabling the servo motor 3 to adjust its output in advance when the desired speed command changes, thereby significantly reducing response lag and improving the continuity and stability of the printing process.

[0118] Feedback control items:

[0119]

[0120] in, It is a proportional-integral-derivative controller, based on the speed error. Fine-tuning is performed to eliminate steady-state errors and ensure long-term accuracy.

[0121] The desired extrusion speed;

[0122] The actual velocity measured by the discharge port flow rate monitoring sensor 11 is the basis of closed-loop control.

[0123] The adaptive coefficient is related to the proportion of remaining clay volume, which is calculated by the following formula:

[0124]

[0125] in, The remaining mud volume ratio is a value that varies from 1.0 (full) to 0.0 (empty).

[0126] The volume of the remaining mud is calculated using motor sensor 9;

[0127] This is the initial filling volume of barrel 6;

[0128]

[0129] The position information is accumulated by motor sensor 9. The reduction ratio, The diameter of the screw. The screw pitch is... Let be the cross-sectional area of ​​the screw.

[0130] Through the above calculations, the system can know the amount of remaining mud in the barrel in real time, thereby achieving adaptive control of the extrusion process.

[0131] The stopped state executes a composite stopping algorithm based on pressure sensing and flow rate feedback, including feedforward retracement amount and feedback retracement amount;

[0132] Feedforward pullback:

[0133]

[0134] in, This is the pressure backflow coefficient, expressed in mm / MPa, and needs to be calibrated experimentally.

[0135] The real-time pressure captured by pressure sensor 10 is the pressure sensor reading captured at the moment the stop command is issued;

[0136] This is a material level adaptive function used to adjust the back-pushing force based on the amount of remaining mud.

[0137] Feedback on pullback amount:

[0138]

[0139] in, The velocity feedback gain is expressed in mm / (mm / s).

[0140] This is the actual measured speed;

[0141] This is the velocity integral feedback gain, measured in mm / (mm·s), used to eliminate steady-state errors and ensure that the flow velocity eventually reaches zero.

[0142] The time integral of the extrusion speed;

[0143] Motor control module according to Generate reverse drive commands to quickly stop extrusion and prevent dripping.

[0144] The material level adaptive function adopts one of the following two types:

[0145] Linear functions: ;

[0146] in, This is a material level adaptive function. This represents the volume ratio of the remaining mud. It is a linear proportionality coefficient. The linear bias coefficient needs to be optimized and determined through multiple stop experiments at different initial material levels.

[0147] Nonlinear functions: ;

[0148] in, This is a material level adaptive function. These are nonlinear coefficients. This is the second offset of the remaining volume ratio relative to the full-load state, ensuring that the correction amount is always positive.

[0149] , and The optimal solution needs to be determined through multiple stop experiments at different initial material levels.

[0150] This embodiment also provides a control method for a lightweight slurry material extrusion device, including the following steps:

[0151] First, external command input:

[0152] The external control system sets thresholds (desired extrusion speed and start / stop command), sends the desired extrusion speed and start / stop command to the signal monitoring module, and performs coordinated control based on the feedback status (READY, WAITING, ERROR).

[0153] Then, servo-driven and extrusion execution is performed:

[0154] Servo motor 3 drives screw 1 to move linearly under the monitoring of motor sensor 9. The front end of screw 1 drives piston 5 to move axially along barrel 6 through push block 1-1, thereby realizing the pressure extrusion of mud. Mud is discharged through barrel front cover 7 and discharge port 8, realizing quantitative continuous feeding.

[0155] Next, signal acquisition and data calculation are performed, such as... Figure 7 As shown:

[0156] The signal monitoring module receives and collects data from the following sensors in real time:

[0157] Motor sensor 9: Detects changes in motor torque and load;

[0158] Pressure sensor 10: Monitors the pressure data inside the barrel;

[0159] Discharge outlet flow rate monitoring sensor 11: Monitors data on the actual discharge flow rate;

[0160] Based on the above real-time data, the volume of remaining clay and the actual discharge rate are calculated, and it is determined whether there is any abnormality in the current state.

[0161] When the motor torque or pressure is detected to exceed the preset threshold, the module sends an error signal to the external control system.

[0162] When the actual flow rate is stable and exceeds the threshold, the module sends a READY signal to the external control system.

[0163] When the actual flow rate is lower than the threshold, the module sends a waiting signal to the external control system.

[0164] Subsequently, operational status identification and motor control:

[0165] The motor control module executes the corresponding control algorithm based on the status signals transmitted by the signal monitoring module.

[0166] In the waiting state (WAITING), the drive screw 1 moves slowly at the initial speed until a stable flow rate is detected;

[0167] In the READY state, when the actual flow rate continuously exceeds the threshold, the motor control module maintains the speed of the servo motor 3 and sends a "slurry ready signal" to the external control system to achieve synchronous start-up;

[0168] In the printing state, the printing state control algorithm (feedforward-feedback composite control algorithm) is executed. Based on the deviation between the expected speed and the actual speed, motor control commands are generated to adjust the speed of servo motor 3, so as to achieve precise control of the output amount.

[0169] In the stop state, the termination state control algorithm (a composite clay extrusion stop algorithm based on pressure sensing and flow rate feedback) is executed. The required amount of retraction is calculated by combining the pressure sensor 10 and the flow rate feedback, and a motor control command is generated to drive the screw 1 to move in the opposite direction, release the pressure in the barrel 6, and prevent the discharge port 8 from dripping.

[0170] In an error state (ERROR), when the pressure or torque exceeds the threshold, the screw 1 is immediately driven to reverse and retract rapidly to prevent mechanical damage and interrupt the extrusion process to protect the device.

[0171] Finally, the motor control module feeds back the operating status and execution commands to the signal monitoring module and the external control system in real time, forming a closed-loop control process of signal monitoring → control execution → feedback correction, thereby realizing the intelligent and stable operation of the extrusion system.

[0172] This embodiment achieves high-precision, stable, and intelligent control of slurry materials during the extrusion process through innovative structural simplification and lightweight design, combined with a multi-state closed-loop control system and a feedforward-feedback composite control algorithm. It not only effectively solves the problems of asynchronous start-up, lag in speed response, and dripping during stop that exist in traditional open-loop control, but also has the advantages of safety, reliability, strong adaptability, portability, and ease of maintenance. It is particularly suitable for application in aerial additive manufacturing fields such as drones and robotic arms, where weight and control precision are critical.

[0173] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0174] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0175] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A lightweight extrusion device for slurry-like materials, characterized in that, Includes extrusion mechanism, sensor unit and intelligent control system; The extrusion mechanism includes a screw (1), a flange nut (2), a servo motor (3), a barrel rear cover (4), a piston (5), a barrel (6), a barrel front cover (7), and a discharge port (8). The screw (1) is connected to the output shaft of the servo motor (3) via the flange nut (2). The servo motor (3) drives the screw (1) to move linearly. One end of the screw (1) passes through the rear cover (4) of the material cylinder and is connected to the push block (1-1). The push block (1-1) drives the piston (5) to reciprocate inside the material cylinder (6) to squeeze out the mud. The front cover (7) of the material cylinder is installed at the front end of the material cylinder (6). The front cover (7) of the material cylinder has a discharge port (8) at the center of the shaft, which is connected to the inside of the material cylinder (6) for outputting mud. The sensor unit includes a motor sensor (9), a pressure sensor (10), and a discharge port flow rate monitoring sensor (11). The motor sensor (9) is installed on the servo motor (3) to collect the motor speed, position and direction, calculate the position of the screw or piston and calculate the amount of remaining mud. The pressure sensor (10) is installed on the front cover (7) of the barrel and is used to detect the extrusion pressure; The outlet flow rate monitoring sensor (11) is installed on the outlet pipe connected to the outlet (8) and is used to detect the actual extrusion speed. The intelligent control system includes an external control system and a mud extrusion control system; The external control system is used to send the desired extrusion speed, start and stop commands to the mud extrusion control system, and to receive the waiting, preparation and error status signals output by the signal monitoring module. The mud extrusion control system includes a signal monitoring module and a motor control module; The signal monitoring module is connected to the sensor unit and is used to collect and preprocess the speed, torque, position signals of the servo motor (3) and the actual flow rate signal of the discharge port, calculate the amount of remaining mud in real time, and determine the operating status. The motor control module is connected to the servo motor (3) and is used to execute the feedforward-feedback composite control algorithm and the stop-pullback algorithm according to the instructions of the external control system and the feedback of the signal monitoring module, generate motor drive instructions, and realize closed-loop control of the extrusion process; The intelligent control system adopts a multi-state management mechanism, including waiting to extrude, ready, printing, stopped, and error reporting states; each state is triggered according to sensor signals. The waiting-to-extrusion state: When the external control system sends a start command to the mud extrusion control system, the servo motor (3) rotates at a preset initial speed and continuously monitors the discharge port flow rate measured by the discharge port flow rate monitoring sensor (11) to prevent the print head from moving prematurely before discharge. The ready state: when the actual flow rate continues to exceed the threshold, the rotation speed of the servo motor (3) is maintained and a signal that the mud is ready is sent to the external control system to achieve synchronous start-up; The printing state: When the main system enters the printing process, a feedforward-feedback composite control algorithm is executed to dynamically adjust the motor speed according to the deviation between the expected extrusion speed and the actual speed, thereby reducing response lag and eliminating steady-state error; The stop state: When a stop command is received, the required amount of back-pulling is calculated based on the pressure value measured by the pressure sensor (10) and the flow rate feedback. The screw (1) is driven to move in the opposite direction to release the pressure of the mud in the barrel (6), so that the mud in the outlet (8) stops immediately, thereby avoiding mud accumulation and leakage at the outlet (8). The error reporting status is as follows: when the motor torque exceeds the preset threshold, an emergency retraction operation is immediately performed to prevent damage to the device due to material blockage or overload. The printing state employs a feedforward-feedback composite control algorithm, and its target rotational speed is given by the following formula: ， Feedforward control terms: ； in, For the desired extrusion speed, The screw pitch is... This refers to the motor-screw transmission ratio. For adaptive coefficients, To accelerate the compensation coefficient, For the desired acceleration; Feedback control items: , in, It is a proportional-integral-derivative controller. For the desired extrusion speed, The actual velocity is measured by the discharge port flow rate monitoring sensor (11).

2. The lightweight slurry material extrusion device according to claim 1, characterized in that, The adaptive coefficient is related to the volume ratio of the remaining mud, which is calculated by the following formula: ， in, This represents the volume ratio of the remaining mud. For the remaining volume, This represents the initial filling volume of the barrel; ， The position information is accumulated by the motor sensor (9). For the reduction ratio, The diameter of the screw. The screw pitch is... Let be the cross-sectional area of ​​the screw.

3. The lightweight slurry material extrusion device according to claim 2, characterized in that, The execution of the stop state is based on a composite stop algorithm of pressure sensing and flow rate feedback, including feedforward retracement amount and feedback retracement amount; The feedforward pullback amount: , in, This is the pressure pullback coefficient. The pressure sensor (10) captures the real-time pressure. This is a material level adaptive function; The feedback pullback amount: , in, For speed feedback gain, For actual speed measurement, For speed integral feedback gain, The time integral of the extrusion speed; The motor control module according to Generate reverse drive commands to quickly stop extrusion and prevent dripping.

4. The lightweight slurry material extrusion device according to claim 3, characterized in that, The material level adaptive function adopts one of the following two types: Linear functions: ; in, This is a material level adaptive function. This represents the volume ratio of the remaining mud. It is a linear proportionality coefficient. The linear bias coefficient; Nonlinear functions: ; in, This is a material level adaptive function. These are nonlinear coefficients. This is the second offset of the remaining volume ratio relative to the full-load state, ensuring that the correction amount is always positive.

5. A control method for a lightweight slurry material extrusion apparatus according to claim 4, comprising the following steps: Step S1: The external control system sends the desired extrusion speed and start / stop commands; Step S2: The servo motor (3) drives the screw (1) to move linearly under the monitoring of the motor sensor (9). The screw (1) drives the piston (5) to move axially along the barrel (6) through the push block (1-1), thereby pressurizing and extruding the mud. The mud is discharged through the barrel front cover (7) and the discharge port (8). Step S3: The signal monitoring module collects data from the motor sensor (9), pressure sensor (10) and discharge port flow rate monitoring sensor (11) in real time, and calculates the remaining mud volume and the actual discharge speed. Step S4: The motor control module determines its operating status based on the acquired signals. While waiting for extrusion, the drive screw (1) moves at an initial speed until a stable flow rate is detected; In the ready state: when the actual flow rate continues to exceed the threshold, the rotation speed of the servo motor (3) is maintained and a mud material ready signal is sent to the external control system to achieve synchronous start-up; In the printing state, the feedforward-feedback composite control algorithm is executed to adjust the speed of the servo motor (3) according to the deviation between the expected speed and the actual speed, so as to achieve precise control of the output amount; In the stopped state, the required amount of backflow is calculated by combining the pressure sensor (10) and flow rate feedback, and the screw (1) is driven to move in the opposite direction to release the pressure inside the barrel (6) and prevent leakage from the outlet (8); In the error state, when the pressure or torque exceeds the threshold, the screw (1) is immediately driven to reverse and quickly retract to protect the device.

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