Dual-wheel milling micro-feeding servo control system and method

Abstract

This application discloses a dual-wheel milling micron-level feed servo control system and method, belonging to the field of engineering machinery technology. It includes a sensing unit, an analysis unit, a decision-making unit, and an execution unit connected in sequence via communication. This invention constructs a three-level progressive feed control mechanism for the milling head by connecting independent micro-feed modules in series between the lifting cylinder and the intermediate pulley. This not only effectively reduces the inherent residual errors caused by hydraulic oil compressibility, servo valve hysteresis, oil temperature drift, and cylinder creep, but also retains the advantages of heavy-duty and long-stroke hydraulic systems, enabling the overall system feed accuracy to reach the micron level, meeting the stringent construction requirements for the flatness of ultra-deep underground continuous walls. Through the sensing and analysis units, it can accurately capture the elastic rebound and high-frequency vibration of a single cutting tooth cutting into the rock, and also eliminate the problem of uneven chip thickness at its source, avoiding uneven wear of the milling wheel and extending the service life of the milling wheel cutter.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery technology, and in particular to a dual-wheel milling micron-level feed servo control system and method. Background Technology

[0002] Twin-wheel trenching machines are core equipment in the field of underground foundation engineering construction. They are widely used in various major foundation projects such as seepage prevention walls in water conservancy and hydropower strata, ultra-deep diaphragm walls, and large deep foundation pit support. The stability and precision of their milling feed directly determine the verticality of the trench, the integrity of the wall, and the overall construction quality. As underground engineering continues to expand into deeper and more complex strata, the construction of ultra-deep diaphragm walls and hard rock strata places stringent requirements on the feed control precision of twin-wheel trenching machines, ranging from millimeter-level to micrometer-level. Existing hydraulic feed control methods are no longer sufficient to meet the precision construction needs of extreme projects.

[0003] Currently, the feed control technology of twin-wheel milling machines has undergone two generations of development. The first generation adopted a feed method of direct traction by a single winch. During operation, the winch needed to run under heavy load continuously to provide cutting and lifting force, resulting in severe equipment wear, low control accuracy, and inability to achieve stable micro-feed. Based on this, the applicant disclosed a micro-feed device for twin-wheel milling and its usage method in patent publication number CN106245698A. This device constructs a two-stage feed structure of winch (coarse adjustment) and lifting cylinder (fine adjustment) by adding a lifting cylinder and an intermediate pulley inside the hollow mast. This effectively reduces the heavy-load working time of the winch and improves the convenience of feed adjustment to a certain extent. It has been initially applied in conventional stratum construction. The second generation is a dual-wheel milling micro-feed hydraulic control system further developed by the applicant. Through elastic deformation feedforward compensation, automatic shock-free mode switching and formation adaptive control, it can effectively solve the problems of false feed caused by the elastic deformation of the wire rope, low efficiency of manual switching and poor formation adaptability. At the same time, the second-generation feed control technology can improve the feed control accuracy of the dual-wheel milling to the millimeter level, which basically meets the construction requirements of conventional ultra-deep underground continuous walls.

[0004] However, the aforementioned dual-wheel milling micro-feed hydraulic control system still has insurmountable technical defects when facing the construction of the bottom of ultra-deep anti-seepage walls at the level of hundreds of meters and the cutting of hard soil layers, making it difficult to achieve stable micron-level feed.

[0005] Firstly, there is the problem of residual errors caused by the inherent characteristics of hydraulic systems, which cannot be completely eliminated. Specifically, hydraulic systems have inherent precision bottlenecks that cannot be avoided. For example, the compressibility of hydraulic oil, the hysteresis error of servo proportional valves, viscosity drift caused by oil temperature changes, and the creeping phenomenon of lifting cylinders at low speeds all contribute to micron-level feed deviations. The combined effect of these factors limits the actual feed accuracy of existing hydraulic systems to only 0.1mm, meaning the feed control accuracy can only be improved to the millimeter level. Therefore, it is difficult to meet the stringent construction requirements of micron-level flatness for ultra-deep underground continuous walls. Especially during continuous construction, sub-millimeter-level errors accumulate with the milling depth, ultimately leading to insufficient trench flatness or excessive verticality errors, affecting construction quality.

[0006] Secondly, existing feed control technologies are only suitable for macroscopic geological conditions and cannot respond to micron-level dynamic fluctuations during single-tooth cutting. Specifically, existing dual-wheel milling micro-feed hydraulic control systems employ macroscopic control logic at the geological level, resulting in long control cycles. They can only identify and adjust feed parameters for a relatively large range of geological characteristic changes. However, during hard rock cutting, the moment a single tooth of the milling wheel cuts into the rock, it generates elastic rebound and high-frequency vibration. This process is extremely short-lived, making it difficult for existing hydraulic systems to capture and compensate for it. This can easily lead to significant differences in the actual chip thickness of each tooth on the same milling wheel, causing uneven wear of the milling wheel. At the same time, the microscopic vibration of the tooth is directly imprinted on the trench wall, resulting in insufficient flatness of the trench wall surface and causing poor fit and increased sealing gaps during subsequent diaphragm wall splicing. This reduces the impermeability and long-term durability of the diaphragm wall. Summary of the Invention

[0007] The main objective of this invention is to overcome the shortcomings of existing technologies and provide a dual-wheel milling micron-level feed servo control system that can effectively reduce residual errors in hydraulic systems, respond in real time to micron-level dynamic fluctuations during single-tooth cutting, achieve stable micron-level feed control of the milling wheel, and improve grooving quality and tool life. This invention also provides a dual-wheel milling micron-level feed servo control method.

[0008] To achieve the above objectives, the present invention provides a micron-level feed servo control system for dual-wheel milling, which is applied to the micro-feed device of dual-wheel milling. The micro-feed device of dual-wheel milling includes a milling head, a lifting cylinder, a winch, a wire rope and an intermediate pulley, and includes a sensing unit, an analysis unit, a decision-making unit and an execution unit that are connected in sequence.

[0009] The sensing unit is configured to collect the actual displacement of the milling head, the torque fluctuation and temperature drift data of the single tooth cutting of the milling wheel, and generate a multi-source dataset;

[0010] The analysis unit includes an adjustment module and a compensation module. The adjustment module is used to output the single-tooth level elastic rebound compensation amount, and the adjustment module has built-in stiffness identification logic and single-tooth adjustment logic. The compensation module is used to output the residual deformation compensation amount of the wire rope and the wear compensation amount of the milling wheel tooth tip, and the compensation module has built-in layered compensation logic and tooth tip prediction logic.

[0011] The decision-making unit includes a collaborative control module for generating three-level feed collaborative control commands. The collaborative control module has built-in normal collaborative logic, switching collaborative logic, and abnormal collaborative logic.

[0012] The execution unit includes a micro-feed module and a status feedback module; the micro-feed module is connected in series between the piston rod of the lifting cylinder and the intermediate pulley and is used to perform displacement compensation; the status feedback module is used to collect execution status data and feed it back to the decision unit to form closed-loop control.

[0013] Preferably, in the stiffness identification logic, the formula for calculating contact stiffness is: .

[0014] Preferably, the single-tooth adjustment logic is configured to adjust based on the identified contact stiffness. Predict the elastic rebound amount when the next cutting tooth enters. 10ms before the next cutting tooth enters, the micro-feed module is driven to extend by the corresponding length in advance to counteract elastic rebound and ensure that the actual chip thickness is consistent with the theoretical value.

[0015] Preferably, in the layered compensation logic, the total elastic deformation of the wire rope is decomposed into three independent parts, and the calculation formula is as follows: .

[0016] Preferably, the compensation module also incorporates an equivalent elastic modulus identification logic, which is configured to inject a step displacement excitation into the micro-feed module when the lifting cylinder supports the weight of the milling head, the winch releases the main load, and the wire rope maintains a slight pretension. Simultaneously, the tension change of the wire rope is collected. Calculate the equivalent elastic modulus of the current wire rope. The equivalent elastic modulus of the steel wire rope The calculation formula is: .

[0017] Preferably, in the tooth tip prediction logic, the formula for calculating the cumulative wear is: .

[0018] Preferably, the normal collaborative logic is configured such that the lifting cylinder is responsible for millimeter-level macro-feed and bears the main cutting load, and the micro-feed module is responsible for micrometer-level dynamic correction; the switching collaborative logic is configured such that when the lifting cylinder reaches a preset threshold of its maximum stroke to start the mode switching process, the micro-feed module maintains its current output unchanged, and automatically resets to the midpoint of the stroke after the lifting cylinder has finished switching, and the moving speed during the reset process is synchronized with the lifting cylinder feed speed.

[0019] Preferably, the abnormal coordination logic is configured such that when the milling wheel torque exceeds the micron-level retraction threshold of the rated torque, the micro-feed module performs a micron-level retraction of 5μm-10μm; if the torque continues to rise and exceeds the millimeter-level retraction threshold of the rated torque, then the lifting cylinder performs a millimeter-level retraction.

[0020] Preferably, the sensing unit includes a strain ring, a displacement detection module, and a temperature compensation module. The strain ring is sleeved on the spindle end of the milling wheel. The displacement detection module is used to detect the actual micron-level displacement of the milling head and feed it back to the decision unit. The temperature compensation module is used to collect temperature data to compensate for the error caused by hydraulic oil viscosity drift and thermal expansion and contraction of the mechanical structure.

[0021] A dual-wheel milling micron-level feed servo control method, employing the dual-wheel milling micron-level feed servo control system as described above, specifically includes the following steps:

[0022] S1: After the original hydraulic system completes sensor self-test, communication link detection and actuator calibration, the decision unit drives the micro-feed module to perform full-stroke reciprocating motion, generates command displacement-actual displacement calibration curve, and performs zero-point calibration on the sensing unit to eliminate installation errors and temperature drift. After the self-test is completed, it enters standby mode.

[0023] S2: The original controller controls the winch and lifting cylinder to complete the coarse positioning of the milling head. The milling wheel cuts into the formation at low speed. The original controller identifies the macroscopic formation type. The analysis unit synchronously collects the initial torque data and establishes the benchmark value of the stiffness identification logic.

[0024] S3: During normal milling operations, the sensing unit collects single-tooth micro-torque, milling wheel head displacement and temperature data in real time and transmits them to the analysis unit; the analysis unit performs single-tooth adjustment, layer compensation and tooth tip prediction in real time, and outputs the total compensation amount to the decision unit; the decision unit generates collaborative control commands to drive the micro-feed module to perform micron-level displacement correction, and the status feedback module feeds back the actual execution status to form micron-level closed-loop control;

[0025] S4: When the lifting cylinder reaches the preset threshold of its maximum stroke, the collaborative control module performs a shock-free mode switch, and the micro-feed module maintains its current output. After the switch is completed, the micro-feed module automatically resets to the midpoint of the stroke at a speed synchronized with the feeding speed of the lifting cylinder, preparing for the next round of micro-feed compensation.

[0026] S5: Every hour of construction, a modulus identification is performed once to update the layered compensation model parameters under the condition that the lifting cylinder supports the weight of the milling head, the winch releases the main load, and the wire rope is kept under slight tension. Every 8 hours of construction, a system zero-point calibration is automatically performed to eliminate drift errors caused by long-term operation and maintain micron-level feed accuracy.

[0027] Beneficial effects:

[0028] 1. The dual-wheel milling micron-level feed servo control system of this invention constructs a three-level progressive feed control mechanism for the milling head by connecting independent micro-feed modules in series between the lifting cylinder and the intermediate pulley. This not only effectively reduces the inherent residual errors caused by hydraulic oil compressibility, servo valve hysteresis, oil temperature drift and cylinder creep, but also retains the advantages of heavy load and long stroke of the hydraulic system, so that the overall feed accuracy of the system reaches the micron level, meeting the stringent construction requirements for the flatness of ultra-deep underground continuous walls.

[0029] 2. The dual-wheel milling micron-level feed servo control system of this invention collects single-tooth cutting torque data at a high sampling rate through the sensing unit, and combines the single-tooth stiffness identification and pre-compensation logic of the analysis unit, thereby refining the control granularity from the stratigraphic level to the single-tooth level. It can not only accurately capture the elastic rebound and high-frequency vibration of a single cutting tooth when it cuts into the rock, but also eliminate the problem of uneven chip thickness from the root, avoid uneven wear of the milling wheel, and significantly improve the flatness of the groove wall.

[0030] 3. The dual-wheel milling micron-level feed servo control system of this invention decomposes the total elastic deformation into three independent components and identifies the equivalent elastic modulus online through the wire rope layered compensation logic built into the compensation module. This solves the problem of inaccurate compensation caused by the assumption of a constant elastic modulus in the prior art. It can not only significantly improve the accuracy of wire rope elastic deformation compensation, but also effectively avoid the continuous accumulation of sub-millimeter residual deformation with the construction depth and reduce the risk of exceeding the standard of trench verticality error.

[0031] 4. The dual-wheel milling micron-level feed servo control system of the present invention can predict the cumulative wear of the tooth tip in real time based on the cutting parameters and perform feedforward compensation through the tooth tip prediction logic built into the compensation module. This can solve the problem of cumulative error of micron-level wear of tooth tips during hard rock cutting. It can not only ensure that the cutting depth of each tooth is consistent, but also avoid the wear error from continuously amplifying with the milling depth, thus ensuring the overall flatness of the bottom of the groove.

[0032] 5. The dual-wheel milling micron-level feed servo control system of the present invention can achieve shock-free coordinated operation of the three-level feed system through the three types of cooperative logic and state feedback closed-loop control built into the cooperative control module. It can not only maintain the feed accuracy without interruption during mode switching, but also maximize the continuity of construction while preventing drill jamming through the graded back-off mechanism, thereby further improving the control stability and reliability of the system. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a flowchart of the steps of a dual-wheel milling micron-level feed servo control method according to an embodiment of the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0038] In the description of this application, it should be noted that the use of terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" to indicate orientation or positional relationships is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships commonly used when the product is in use. These terms are used solely for the convenience of describing this application and for 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 application. Furthermore, the use of terms such as "first" and "second" in the description of this application is only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0039] Furthermore, the use of terms such as "horizontal" and "vertical" in the description of this application does not imply that the component is required to be absolutely horizontal or suspended, but rather that it may be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but rather that it may be slightly tilted.

[0040] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0041] Example 1:

[0042] This invention proposes a dual-wheel milling micron-level feed servo control system.

[0043] In one embodiment of the present invention, the dual-wheel milling micron-level feed servo control system is applied to the micro-feed device of the dual-wheel milling machine. The micro-feed device of the dual-wheel milling machine includes a milling head, a lifting cylinder, a winch, a wire rope and an intermediate pulley, and includes a sensing unit, an analysis unit, a decision-making unit and an execution unit that are connected in sequence.

[0044] The sensing unit is configured to collect data on the actual displacement of the milling head, torque fluctuations during single-tooth cutting of the milling wheel, and temperature drift, and generate multi-source datasets.

[0045] The analysis unit includes an adjustment module and a compensation module. The adjustment module is used to output the single-tooth level elastic rebound compensation amount, and the adjustment module has built-in stiffness identification logic and single-tooth adjustment logic. The compensation module is used to output the residual deformation compensation amount of the wire rope and the wear compensation amount of the milling wheel tooth tip, and the compensation module has built-in layered compensation logic and tooth tip prediction logic.

[0046] The decision-making unit includes a collaborative control module for generating three-level feed collaborative control commands. The collaborative control module has built-in normal collaborative logic, switching collaborative logic, and abnormal collaborative logic.

[0047] The execution unit includes a micro-feed module and a status feedback module; the micro-feed module is connected in series between the piston rod of the lifting cylinder and the intermediate pulley and is used to perform displacement compensation; the status feedback module is used to collect execution status data and feed it back to the decision unit to form closed-loop control.

[0048] It should be noted that the micro-feed device for the dual-wheel milling machine in this embodiment can be the micro-feed device for the dual-wheel milling machine disclosed in the applicant's patent with publication number CN106245698A. This micro-feed device for the dual-wheel milling machine uses a hollow mast as the basic carrier. A crane is set at the top of the mast. The crane is equipped with guide pulleys and transition pulleys. A lifting cylinder is set in the cavity inside the mast. An intermediate pulley is set at the power output end of the lifting cylinder. One end of the wire rope is connected to the winch. The other end extends from the winch and passes through the guide pulley, intermediate pulley and transition pulley in sequence to suspend the milling head. Thus, the extension and retraction of the lifting cylinder can drive the intermediate pulley to move up and down. Together with the winch's winding and unwinding action, the milling head can be fed and milled on the stratum. The present invention provides a dual-wheel milling micron-level feed servo control system. Without altering the original hydraulic system hardware structure and core control logic, it upgrades the original two-stage hydraulic feed control to a three-stage progressive feed control by adding an independent micron-level control link. This solves the technical problems in the prior art of eliminating the inherent residual error of hydraulic system feed and the inability to respond to dynamic fluctuations in single-tooth cutting.

[0049] Working principle: In the construction of ultra-deep hard rock formations, the dual-wheel milling micron-level feed servo control system of this invention can upgrade the milling head's millimeter-level hydraulic feed control to micron-level closed-loop intelligent control through the sequentially connected sensing unit, analysis unit, decision-making unit and execution unit. This can effectively solve the problems of difficult elimination of inherent hydraulic residual error and inability to respond to dynamic fluctuations in single-tooth cutting that exist in the existing dual-wheel milling micro-feed devices.

[0050] Specifically, the dual-wheel milling micron-level feed servo control system of this invention adopts a hierarchical control architecture consisting of a sensing unit, an analysis unit, a decision-making unit, and an execution unit connected in sequence. This architecture enables real-time data interaction and hierarchical instruction transmission between the units, forming a complete micron-level closed-loop control loop. First, the sensing unit, as the system's signal acquisition entry point, continuously collects three core data types: the actual displacement of the milling head, the torque fluctuation of the single-tooth cutting of the milling wheel, and temperature drift. These data are then integrated into a unified format multi-source dataset and transmitted to the analysis unit. Next, the analysis unit, as the core computing hub, processes different types of micron-level errors through the adjustment and compensation modules and outputs the corresponding compensation amounts to the decision-making unit. Subsequently, the decision-making unit generates three-level feed collaborative control instructions based on the specific working conditions of the current construction and issues them to the execution unit. Finally, the execution unit drives the milling head to complete the corresponding micron-level displacement compensation action according to the instructions of the decision-making unit. After the action is completed, the execution unit transmits the actual execution status back to the decision-making unit through the status feedback module, thereby achieving closed-loop correction of the entire control process of the micron-level feed milling motion of the milling head. Furthermore, the dual-wheel milling micron-level feed servo control system of this invention can achieve elastic rebound prediction compensation for the moment a single cutter tooth cuts into the rock through the built-in adjustment module. The compensation module can achieve comprehensive correction of multi-source errors of the hydraulic system, wire rope and milling wheel tooth tip. Moreover, the collaborative control module can achieve three-level feed without impact coordination of the lifting cylinder, winch and micro-feed module. Thus, it can ensure that the milling head can achieve stable, accurate and continuous micron-level feed operation under ultra-deep and complex strata conditions, significantly improving the trenching quality and tool life.

[0051] Furthermore, addressing the issue of increased residual errors in existing control technologies due to the inherent characteristics of hydraulic systems, this invention's dual-wheel milling micron-level feed servo control system constructs a three-stage progressive feed control mechanism. This mechanism utilizes an independent micro-feed module connected in series between the piston rod of the lifting cylinder and the intermediate pulley. This mechanism achieves meter-level coarse adjustment for the winch, millimeter-level fine adjustment for the lifting cylinder, and micron-level ultra-fine adjustment for the micro-feed module, thus breaking through the 0.1mm accuracy limit of existing hydraulic systems. Specifically, existing hydraulic systems are constrained by the compressibility of hydraulic oil, hysteresis error of the servo proportional valve, viscosity drift caused by oil temperature changes, and low-speed creeping of the lifting cylinder. Their actual feed accuracy is difficult to surpass the millimeter-level limit and cannot reach the micron level, and these inherent defects cannot be completely eliminated through optimized control algorithms. In contrast, the micro-feed module of this invention's dual-wheel milling micron-level feed servo control system, acting as the end effector, can be connected in series between the piston rod of the lifting cylinder and the intermediate pulley, directly outputting micron-level displacement corrections. The micro-feed module can employ a digital servo hydraulic cylinder. This cylinder uses a stepper motor to drive a precision ball screw, which in turn moves the valve core. The valve core controls the flow distribution of the main cylinder. The piston of the main cylinder is linked to the valve core via a mechanical feedback rod, forming a purely mechanical closed loop. This eliminates the need for external displacement sensors, enabling high-precision displacement output. Furthermore, it features strong anti-pollution capabilities, good impact resistance, fast response speed, and no hydraulic hysteresis, making it perfectly suited for harsh working conditions such as strong vibrations during twin-wheel milling operations. Additionally, this invention provides a micron-level feed servo control system for twin-wheel milling. The micro-feed module of the system is specifically designed to handle micron-level dynamic correction tasks. The original hydraulic system only needs to handle more than 99% of the main cutting load (of which the winch completes meter-level coarse adjustment and the lifting cylinder completes millimeter-level fine adjustment). The division of labor between the micro-feed module and the original hydraulic system is clear and they do not interfere with each other. Thus, it retains the advantages of the hydraulic system in terms of heavy load, long stroke and strong impact resistance, while reducing the inherent residual error of the hydraulic system through an independent micron-level control link. This enables the overall feed accuracy of the system to reach the micron level, effectively meeting the stringent construction requirements for the flatness of ultra-deep underground continuous walls.

[0052] Understandably, existing hydraulic feed control technology is only suitable for macroscopic geological conditions and cannot respond to micron-level dynamic fluctuations during single-tooth cutting. This invention's dual-wheel milling micron-level feed servo control system, through the coordinated operation of sensing and analysis units, refines control precision from the geological level to the single-tooth level, achieving real-time and precise control of the cutting process of a single cutting tooth. Specifically, the original dual-wheel milling micro-feed hydraulic control system uses macroscopic control logic at the geological level, with a control cycle typically exceeding 200ms. It can only identify and adjust feed parameters for large-scale geological characteristic changes, failing to capture the elastic rebound and high-frequency vibration that last only tens of milliseconds during the moment a single cutting tooth enters the rock. The sensing unit of the dual-wheel milling micron-level feed servo control system of this invention can collect torque fluctuation data of single-tooth cutting of the milling wheel at a sampling frequency much higher than that of the original hydraulic system, and thus accurately capture the instantaneous load change when each tooth cuts into the rock. The adjustment module of the analysis unit has built-in stiffness identification logic and single-tooth adjustment logic, which can calculate the contact stiffness between the tooth and the rock in real time based on the collected single-tooth torque data, and predict the elastic rebound amount when the next tooth cuts in. Before the tooth cuts in, a compensation command is generated in advance and the micro-feed module is driven to execute the compensation action. This can fundamentally avoid the problem of uneven chip thickness during single-tooth cutting, avoid non-uniform wear caused by uneven force on each tooth on the same milling wheel, and also reduce the traces left by the micro vibration of the tooth on the groove wall, significantly improving the flatness of the groove wall.

[0053] It is worth noting that the analysis unit of the dual-wheel milling micron-level feed servo control system of this invention also achieves accurate compensation for two types of micron-level errors not covered by the original technology through the compensation module, further improving the error compensation system. The original dual-wheel milling micro-feed hydraulic control system only solved the macroscopic elastic deformation problem of the wire rope through elastic deformation feedforward compensation, but assumed that the elastic modulus of the wire rope was a constant value. Therefore, it ignored the residual deformation caused by the closure of the wire rope strands, the elastic deformation of the steel core, and the relaxation of the helical structure after long-term use during the stress process. It also did not consider the cumulative error of micron-level wear generated by the milling wheel tooth tip during hard rock cutting. The compensation module of the dual-wheel milling micron-level feed servo control system of this invention incorporates layered compensation logic and tooth tip prediction logic. The layered compensation logic decomposes the total elastic deformation of the wire rope into three independent components: strand closure deformation, core elastic deformation, and residual relaxation deformation. It can also identify the current equivalent elastic modulus of the wire rope online to update the compensation model parameters in real time. This significantly improves the accuracy of wire rope elastic deformation compensation, effectively prevents the accumulation of sub-millimeter residual deformation with increasing construction depth, reduces the risk of insufficient groove flatness and excessive perpendicularity error, extends the service life of the wire rope, and lowers maintenance costs. Furthermore, the tooth tip prediction logic can predict the cumulative wear of the milling wheel teeth in real time based on cutting parameters and use this as a feedforward input for compensation. This avoids the accumulation of sub-millimeter errors with increasing milling depth, which could ultimately lead to insufficient groove flatness or excessive perpendicularity error.

[0054] Furthermore, the collaborative control module of the dual-wheel milling micron-level feed servo control system of this invention incorporates normal collaborative logic, switching collaborative logic, and abnormal collaborative logic. The normal collaborative logic clarifies the division of labor between the lifting cylinder and the micro-feed module during normal milling head operation, ensuring smooth coordination and each fulfilling its specific function. The switching collaborative logic maintains the output of the micro-feed module while the lifting cylinder and winch switch feed modes, effectively preventing feed accuracy interruptions during switching. After switching, the micro-feed module automatically resets to the midpoint of its stroke, providing sufficient margin for the next compensation. In cases of abnormal milling head conditions, the abnormal collaborative logic implements a graded backoff mechanism. The micro-feed module is prioritized for micron-level backoff to alleviate excessive cutting load, while the lifting cylinder's millimeter-level backoff is only triggered when the load continues to exceed limits. This prevents drill jamming while maximizing the continuity of the operation. In addition, the status feedback module in the execution unit can collect the actual execution status of the micro-feed module in real time and feed it back to the decision unit, thereby forming a complete micron-level closed-loop control loop, effectively ensuring that all compensation commands can be executed accurately, and further improving control accuracy and reliability.

[0055] Example 2:

[0056] This embodiment, based on Embodiment 1, further refines and defines the stiffness identification logic and single-tooth adjustment logic built into the adjustment module of the analysis unit. The core of this embodiment lies in establishing a quantitative calculation model for the contact stiffness of the cutting tooth and rock, thereby achieving accurate prediction and advance compensation for the elastic rebound during single-tooth cutting. This fundamentally solves the technical problem that the original macroscopic control logic cannot respond to the micron-level dynamic fluctuations of single-tooth cutting. Specifically, in the stiffness identification logic, the formula for calculating the contact stiffness is: .

[0057] In the formula, The contact stiffness between the cutting teeth and the rock is a core parameter that reflects the hardness of the rock and the cutting characteristics of the cutting teeth. The larger the value, the harder the rock and the greater the elastic rebound when the cutting teeth cut in. The torque increment when a single cutting tooth cuts into the rock is obtained by the milling wheel shaft end strain ring in the sensing unit at a sampling frequency of more than 5kHz. After removing high-frequency noise through moving average filtering, the difference between the peak torque during the cutting process of each cutting tooth and the no-load torque is extracted and calculated. The instantaneous elastic deformation of the cutter tooth-rock contact surface, captured by a high sampling rate displacement sensor (the value is much smaller than the theoretical chip thickness, and is the direct cause of micron-level vibration and uneven groove wall). This is the effective cutting radius of the milling wheel.

[0058] The complete execution process of the stiffness identification logic is as follows: During the milling operation, the sensing unit continuously collects the torque signal from the milling wheel shaft end and transmits it to the analysis unit. The adjustment module performs synchronous tooth segmentation processing on the torque data according to the milling wheel speed signal, dividing the continuous torque signal into independent cutting torque segments corresponding to each cutting tooth. Subsequently, the adjustment module calculates the torque increment within each cutting tooth segment. And combined with the current instantaneous elastic deformation Substituting the values ​​into the contact stiffness calculation formula, the current contact stiffness between the cutting edge and the rock is calculated in real time. Since the contact stiffness of the same stratum has a certain stability, the adjustment module will perform weighted averaging on the contact stiffness calculation results of multiple consecutive cutter teeth to eliminate the influence of random fluctuations during the cutting process of a single cutter tooth and obtain a more accurate average contact stiffness value of the stratum.

[0059] Furthermore, based on the real-time identified knife-tooth-rock contact stiffness The single-tooth adjustment logic can accurately predict the elastic rebound amount when the next tooth cuts into the rock. According to the definition of contact stiffness By inversely solving the displacement, the formula for calculating the elastic rebound can be obtained as follows: The single-tooth adjustment logic is configured to drive the micro-feed module to extend ahead of the elastic rebound 10ms before the next tooth cuts into the rock. Equal displacement amounts allow the micro-feed module to compensate for the displacement in advance when the milling wheel teeth actually cut into the rock, thus counteracting the elastic rebound of the rock and ensuring that the actual chip thickness of the teeth remains consistent with the theoretical chip thickness. This advance prediction and compensation method effectively solves the lag problem of the original feedback control and can capture and compensate for the dynamic fluctuations of single-tooth cutting that last only tens of milliseconds.

[0060] This embodiment, through the synergistic effect of the stiffness identification logic and the single-tooth adjustment logic, can refine the control granularity of the milling head feed control from the existing stratum level to the single-tooth level, and significantly shorten the control response time from more than 200ms to less than 10ms. This not only eliminates the problem of uneven chip thickness in the single-tooth cutting process at its source, but also improves the uniformity of the actual cutting load of each tooth on the same milling wheel. This significantly reduces the non-uniform wear of the tool, extends the tool's service life, and effectively eliminates the traces left by the micro-vibration of the tooth on the trench wall, improving the flatness of the trench wall surface. In turn, it improves the fit and sealing performance of the subsequent diaphragm wall splicing, and enhances the impermeability and long-term durability of the diaphragm wall.

[0061] Example 3:

[0062] This embodiment, based on Embodiment 2, further refines and defines the layered compensation logic and online modulus identification logic built into the compensation module in the analysis unit. The core of this embodiment lies in establishing a multi-component layered deformation model and an online parameter identification mechanism to address the problem of compensation accuracy attenuation caused by the relaxation of the spiral structure after long-term use of the wire rope, thereby eliminating the risk of sub-millimeter residual deformation accumulating with construction depth. Specifically, in the layered compensation logic, the total elastic deformation of the wire rope is decomposed into three independent parts, calculated using the following formula: .

[0063] In the formula, The total elastic deformation of the wire rope is the core output parameter that the compensation module needs to calculate. This is the closed deformation of the rope strands, which is a nonlinear deformation caused by the gradual closure of the tiny structural gaps between the wires and strands in the early stage of the wire rope being stressed. It is only significant in the initial stage when the load increases from zero. This is the elastic deformation of the steel core, which is the linear elastic deformation of the steel core material itself during the stable period of the wire rope under stress, and conforms to Hooke's Law. The residual deformation caused by the relaxation of the spiral structure is the additional deformation caused by the irreversible relaxation of the internal spiral structure after the wire rope has been subjected to long-term alternating loads. Its value gradually increases with the service time.

[0064] Existing dual-wheel milling micro-feed hydraulic control systems only use a single steel core elastic deformation model for compensation, neglecting the nonlinear characteristics of the strand closure deformation and the cumulative effect of residual relaxation deformation. This results in millimeter-level compensation errors in the elastic deformation of the wire rope during ultra-deep strata construction. In contrast, the layered compensation logic of this invention establishes separate calculation models for the different characteristics of the three deformation components of the wire rope. The strand closure deformation uses an exponential function model to fit its nonlinear variation law, the steel core elastic deformation is calculated using linear Hooke's law, and the residual relaxation deformation is updated in real-time through online identification.

[0065] To obtain the actual elastic characteristics of the wire rope in real time, the compensation module also incorporates equivalent elastic modulus identification logic, the calculation formula of which is as follows: ;

[0066] In the formula, This is the current equivalent modulus of elasticity of the wire rope; The effective suspension length of the wire rope is calculated by combining the data on the lowering length of the wire rope collected by the winch control unit of the original hydraulic system with the pulley block ratio. is the nominal cross-sectional area of ​​the wire rope, and is the inherent structural parameter of the wire rope; The change in tension of the wire rope is obtained by the tension sensor of the original hydraulic system; The actively injected step displacement excitation is output by the micro-feed module.

[0067] The complete execution process of the equivalent elastic modulus identification logic is as follows: With the lifting cylinder supporting the milling head weight, the winch releasing the main load, and the wire rope maintaining a slight preload, the compensation module sends a command to the micro-feed module, actively injecting three consecutive 2μm step displacement excitations. Simultaneously, the tension sensor synchronously collects the tension change data of the wire rope at a sampling frequency of 1kHz. Subsequently, the compensation module uses the least squares method to perform linear fitting on the displacement-tension data, calculating the current equivalent elastic modulus of the wire rope. Finally, the identified equivalent elastic modulus is... By substituting the data into the layered compensation model, the calculation parameters of each deformation component are updated in real time to ensure that the compensation model always remains consistent with the actual state of the wire rope. Furthermore, during normal milling operations, the compensation module calculates the total elastic deformation of the wire rope in real time based on the real-time collected wire rope tension and effective suspension length, combined with the updated layered compensation model. This total elastic deformation is then added as a feedforward compensation amount to the displacement command of the micro-feed module, achieving dynamic and precise compensation for the elastic deformation of the wire rope.

[0068] Understandably, this embodiment, through the synergistic effect of the aforementioned layered compensation logic and online identification logic, can significantly improve the compensation accuracy of the elastic deformation of the wire rope. This not only effectively solves the compensation error problem caused by the assumption of a constant elastic modulus in the prior art, but also avoids the continuous accumulation of sub-millimeter residual deformation with the construction depth and reduces the verticality error of the trench. At the same time, by monitoring the changes in the elastic properties of the wire rope in real time, signs of fatigue damage to the wire rope can be detected in advance, thereby extending the service life of the wire rope and reducing the maintenance cost of the equipment.

[0069] Example 4:

[0070] This embodiment, based on Embodiment 3, further refines and defines the online prediction logic for tooth tip wear built into the compensation module. This embodiment aims to address the shortcomings of existing technologies that address the continuous accumulation of micron-level tooth tip wear under hard rock conditions, leading to excessive groove flatness and perpendicularity, by establishing a tooth tip wear calculation model based on the conservation of cutting energy, solving the cumulative wear of milling wheel tooth tips in real time, and performing feedforward compensation. Specifically, in the tooth tip prediction logic, the formula for calculating the cumulative wear is:

[0071]

[0072] In the formula, This represents the cumulative wear of the milling wheel tooth tips; The formation wear coefficient is derived from the stiffness identification logic and is adaptively selected according to the softness and hardness characteristics of the formation. The real-time cutting torque is acquired in real time by the strain ring of the sensing unit; This refers to the milling wheel speed; This refers to the real-time feed rate for dual-wheel milling machines. The force-wear depth conversion coefficient was calibrated in advance through indoor cutting tests. This is a time-varying element used for time-series integration and accumulation of wear amounts. Furthermore, it should be noted that when... When the speed falls below a preset threshold (e.g., 0.1 mm / s), it is considered an invalid cutting state, and the integration calculation is paused. (In actual construction, this occurs when the lifting cylinder switches strokes or when a momentary stuck drill bit is encountered and micron-level or millimeter-level retraction is performed.) The value may be 0, the integrand approaches infinity, and the integration operation in the digital controller will directly overflow (report an error) or cause a sudden change in the wear calculation, so the integration operation needs to be paused.

[0073] During actual milling operations, the sensing unit continuously collects real-time cutting torque at a fixed sampling frequency. Milling wheel speed With feed rate The data is simultaneously transmitted to the compensation module; the tooth tip prediction logic substitutes real-time operating parameters into the wear calculation formula, performs continuous integration calculations in units of time micro-elements, and accumulates the total cumulative wear of the tooth tip in real time. The formation wear coefficient is automatically matched based on the stiffness identification logic results, without the need for manual assignment, and can adapt to the wear characteristics of different formations such as soft soil, ordinary rock layers, and hard bedrock; the force-wear depth conversion coefficient... After experimental calibration, the data is fixedly written into the control program to ensure the uniformity and accuracy of wear calculations. Furthermore, the tooth tip prediction logic uses the cumulative tooth tip wear obtained in real time as the feedforward control input, which is sent to the decision unit and drives the micro-feed module to extend an additional micrometer-level stroke, thereby offsetting the cutting depth deviation caused by tooth tip wear in real time. The compensation cycle is synchronized with the milling wheel speed, enabling wear compensation to be completed once per revolution of the milling wheel. This ensures that the cutting depth of all teeth remains consistent, effectively avoiding unevenness in the groove wall caused by differences in wear on individual teeth.

[0074] Understandably, this embodiment, through online prediction of tooth tip wear and real-time feedforward compensation, can offset the cumulative effect of micron-level wear on milling wheel teeth during hard rock cutting, thereby eliminating the problem of milling wheel tooth wear error continuously amplifying with milling depth. This not only effectively ensures the overall flatness of the bottom of ultra-deep underground continuous wall, but also balances the actual cutting load of each tooth, reduces uneven wear and dry wear, and further extends the service life of the milling wheel tool, significantly reducing equipment maintenance and replacement costs.

[0075] Example 5:

[0076] This embodiment, based on embodiment 4, further refines and defines the normal collaborative logic and switching collaborative logic built into the collaborative control module in the decision-making unit. This embodiment achieves smooth linkage between the lifting cylinder, winch, and micro-feed module by clarifying the division of labor and coordination rules of the three-stage feed mechanism and the stroke pre-trigger switching mechanism. Specifically, the normal collaborative logic is configured such that the lifting cylinder is responsible for millimeter-level macro-feed and bears the main cutting load, while the micro-feed module is responsible for micrometer-level dynamic correction. The switching collaborative logic is configured such that when the lifting cylinder's stroke reaches a preset threshold of its maximum stroke to initiate the mode switching process, the micro-feed module maintains its current output unchanged, and automatically resets to the midpoint of its stroke after the lifting cylinder completes the switching. During the reset process, the moving speed is synchronized with the lifting cylinder's feed speed.

[0077] In this embodiment, the functional division and operational boundaries of the lifting cylinder and the micro-feed module are clearly defined through the configuration rules of normal collaborative logic. The lifting cylinder mainly undertakes the millimeter-level macro-feed task in the twin-wheel milling operation, while bearing the entire main cutting load and being responsible for the basic feed action of large stroke and heavy load. The micro-feed module does not participate in macro-stroke feed or main load bearing. It mainly performs micron-level dynamic correction of hydraulic residual error, single-tooth elastic rebound error, wire rope deformation error, and milling wheel tooth tip wear error generated during system operation. The two perform their respective functions and work in parallel and collaboratively. The lifting cylinder meets the operational requirements of twin-wheel large stroke heavy-duty milling, while the micro-feed module continuously maintains the micron-level feed accuracy of the whole machine. They do not interfere with each other and complement each other.

[0078] Simultaneously, by switching the configuration rules of the collaborative logic, a preset threshold for mode switching is set based on the maximum stroke of the lifting cylinder. This preset threshold can be set to 90% of the maximum stroke of the lifting cylinder. Specifically, when the lifting cylinder's travel reaches this preset threshold, the system automatically initiates the feed mode switching process between the lifting cylinder and the winch. Throughout the entire feed mode switching process, the micro-feed module maintains a constant current output displacement, and its movement does not fluctuate with load transfer or oil circuit switching, thus ensuring that the micron-level compensation effect is not interrupted and the feed accuracy is not lost. After the lifting cylinder and the winch have completed a smooth load transfer and all feed mode switching is completed, the micro-feed module automatically resets to its midpoint position. During the reset process, the moving speed is strictly synchronized with the original feed speed of the lifting cylinder, thereby effectively avoiding mechanical shock and milling disturbance caused by speed differences, while reserving sufficient stroke adjustment margin for the next round of micron-level dynamic correction.

[0079] Understandably, this embodiment achieves a precise division of labor between millimeter-level macroscopic feed and micrometer-level dynamic correction of the milling head through refined configuration of normal collaborative logic and switching collaborative logic. At the same time, it realizes fully automatic switching of milling head feed mode without impact or accuracy loss. No manual intervention is required for start-up, shutdown and adjustment throughout the process, which can ensure the continuity of milling operations in ultra-deep hard rock formations. It avoids the problems of groove wall disturbance and groove accuracy deviation caused by mode switching, and reduces mechanical impact through speed synchronous reset, effectively protecting core components such as lifting cylinder, wire rope and micro feed module, and improving the stability and service life of equipment operation.

[0080] Example 6:

[0081] This embodiment, based on embodiment 5, further refines and defines the abnormal collaborative logic built into the collaborative control module. Specifically, the abnormal collaborative logic is configured such that when the milling wheel torque exceeds the micron-level retraction threshold of the rated torque, the micro-feed module performs a micron-level retraction of 5μm-10μm; if the torque continues to rise and exceeds the millimeter-level retraction threshold of the rated torque, then the lifting cylinder performs a millimeter-level retraction.

[0082] In this embodiment, considering the characteristics of sudden increases in cutting torque and high risk of drill jamming during twin-wheel milling of hard rock, two levels of torque protection thresholds are set in the abnormal collaborative logic: a micrometer-level retraction threshold and a millimeter-level retraction threshold. Both thresholds are based on the rated torque of the milling wheel. During actual milling operations, the sensing unit can continuously collect milling wheel cutting torque data in real time and upload it synchronously to the decision-making unit. The collaborative control module can compare the measured torque with the preset two-level thresholds to make a judgment, thereby realizing hierarchical risk avoidance control.

[0083] Furthermore, when the milling wheel torque exceeds the micron-level retraction threshold corresponding to the rated torque, the system prioritizes initiating a small-amplitude flexible adjustment. The micro-feed module executes a micron-level retraction action within the range of 5μm-10μm. This releases the instantaneous cutting load by slightly retracting the milling head, thereby buffering the rigid compression between the cutting teeth and the hard rock. This effectively alleviates the torque overload trend without stopping the milling operation or changing the overall feed rhythm, preventing local cutting teeth from chipping or breaking due to excessive instantaneous load, while also avoiding impact torque damage to the milling wheel main bearing. Additionally, if the milling wheel torque continues to rise and exceeds the millimeter-level retraction threshold corresponding to the rated torque after the aforementioned micron-level retraction adjustment, it is determined that the current cutting area contains extreme conditions such as hard rock protrusions or isolated boulders, posing a serious risk of drill jamming. At this point, the system automatically upgrades the protection level, that is, it terminates the small adjustment of the micro-feed module and instead uses the lifting cylinder to perform a millimeter-level retraction action. By removing the main cutting load through a large stroke, the milling wheel is removed from the high-resistance cutting area, completely eliminating the risk of stuck drill. At the same time, after the milling wheel torque drops to below the preset value of the rated torque (selectable as 60%) and stabilizes for several seconds (specifically set to 3 seconds), the system automatically controls the lifting cylinder to slowly cut into the formation at the original feed speed. Meanwhile, the micro-feed module resumes its normal micron-level compensation function and continues continuous milling operations.

[0084] Understandably, this embodiment, by employing a tiered abnormal coordination logic, differs from traditional dual-wheel milling machines that directly use the large-stroke retraction of the lifting cylinder or emergency stop for protection. For most instantaneous torque overloads caused by local fluctuations in formation hardness, the micro-level retraction of the micro-feed module can quickly alleviate the problem without interrupting the milling operation, significantly improving construction continuity. Furthermore, the millimeter-level retraction of the lifting cylinder is only triggered under extreme conditions, effectively avoiding unnecessary construction interruptions. For example, the micro-level retraction threshold is set to 120% of the rated torque, and the millimeter-level retraction threshold is set to 150% of the rated torque. When the torque reaches 120%, a 5μm-10μm micro-retraction is initiated; if it continues to rise to 150%, the millimeter-level retraction of the lifting cylinder is triggered. It should be noted that the above percentage values ​​are merely illustrative examples of this embodiment; specific values ​​can be preset and calibrated in actual applications based on the milling wheel model, tool material, and formation characteristics.

[0085] Example 7:

[0086] This embodiment, based on Embodiment 6, further refines and defines the specific hardware composition, installation method, and working principle of the sensing unit. Specifically, the sensing unit includes a strain ring, a displacement detection module, and a temperature compensation module. The strain ring is fitted onto the end of the milling wheel's spindle; the displacement detection module is used to detect the actual micron-level displacement of the milling head and feed it back to the decision unit; the temperature compensation module is used to collect temperature data to compensate for errors caused by hydraulic oil viscosity drift and thermal expansion and contraction of the mechanical structure.

[0087] In this embodiment, the strain ring, displacement detection module, and temperature compensation module in the sensing unit can synchronously collect data and integrate it into a unified multi-source dataset, thereby addressing the detection requirements of three core parameters: single-tooth cutting torque fluctuation, actual milling head displacement, and system temperature drift. The strain ring is fitted onto the non-drive end of the milling wheel spindle, effectively avoiding measurement interference caused by spindle bending deformation, axial load, and ambient temperature changes. Simultaneously, it can collect minute torque changes in the spindle, accurately capturing the torque fluctuation signal lasting only tens of milliseconds when a single cutting tooth cuts into the rock, providing fundamental data for cutting tooth-rock contact stiffness identification and single-tooth elastic rebound compensation.

[0088] Furthermore, the displacement detection module can be installed between the mast bottom and the milling head. This module can directly detect the actual micron-level displacement of the milling head relative to the mast and simultaneously feed it back to the decision unit. This breaks through the existing control system's reliance on the lifting cylinder stroke to indirectly calculate the milling head's feed displacement, effectively avoiding displacement calculation errors caused by wire rope elastic deformation, pulley transmission clearance, and mechanical assembly clearance. This provides a precise displacement reference for the closed-loop correction of the entire servo control system. In addition, the temperature compensation module can be installed at multiple points in the hydraulic system's oil circuit and on the surfaces of core structures such as the mast and pulley blocks, enabling real-time acquisition of hydraulic oil operating temperature and ambient structural temperature data.

[0089] It should be noted that during construction, fluctuations in oil temperature directly cause changes in the viscosity of the hydraulic oil, which can easily lead to problems such as deviations in the flow control of the servo proportional valve and low-speed crawling of the lifting cylinder. Furthermore, in the construction of ultra-deep underground continuous walls, the large temperature difference in the environment causes thermal expansion and contraction deformation of the metal mechanical structure, resulting in additional feed errors at the micrometer level. This embodiment utilizes a temperature compensation module to integrate the collected temperature data into a multi-source dataset in real time and transmit it to the analysis unit. The system establishes an error correction model based on temperature parameters, thereby dynamically compensating for control errors caused by hydraulic oil viscosity drift and deformation errors caused by thermal expansion and contraction of the mechanical structure. This further eliminates interference factors affecting micrometer-level feed accuracy from the perspective of environmental temperature.

[0090] Understandably, this embodiment, through the reasonable layout and functional configuration of the strain gauge ring, displacement detection module, and temperature compensation module, can not only accurately capture transient torque fluctuations in single-tooth cutting and truly detect the micron-level feed displacement of the milling head, but also achieve active compensation for temperature errors in the hydraulic system and mechanical structure. Furthermore, the entire sensing unit can provide real, reliable, and time-synchronized raw data support for various identification logics, compensation logics, and collaborative control logics of the back-end analysis and decision-making units. This overcomes the shortcomings of existing technologies that rely solely on single working condition parameters, leading to distortion in milling head feed control, and ensures that the milling head can maintain stable micron-level feed control accuracy under complex working conditions such as ultra-deep, hard rock, and variable temperature differences.

[0091] A dual-wheel milling micron-level feed servo control method, implemented based on any of the above embodiments of the dual-wheel milling micron-level feed servo control system, includes the following steps:

[0092] S1: After the original hydraulic system completes sensor self-test, communication link detection and actuator calibration, the decision unit drives the micro-feed module to perform full-stroke reciprocating motion, generates command displacement-actual displacement calibration curve, and performs zero-point calibration on the sensing unit to eliminate installation errors and temperature drift. After the self-test is completed, it enters standby mode.

[0093] S2: The original controller controls the winch and lifting cylinder to complete the coarse positioning of the milling head. The milling wheel cuts into the formation at low speed. The original controller identifies the macroscopic formation type. The analysis unit synchronously collects the initial torque data and establishes the benchmark value of the stiffness identification logic.

[0094] S3: During normal milling operations, the sensing unit collects single-tooth micro-torque, milling wheel head displacement and temperature data in real time and transmits them to the analysis unit; the analysis unit performs single-tooth adjustment, layer compensation and tooth tip prediction in real time, and outputs the total compensation amount to the decision unit; the decision unit generates collaborative control commands to drive the micro-feed module to perform micron-level displacement correction, and the status feedback module feeds back the actual execution status to form micron-level closed-loop control;

[0095] S4: When the lifting cylinder reaches the preset threshold of its maximum stroke, the collaborative control module performs a shock-free mode switch, and the micro-feed module maintains its current output. After the switch is completed, the micro-feed module automatically resets to the midpoint of the stroke at a speed synchronized with the feeding speed of the lifting cylinder, preparing for the next round of micro-feed compensation.

[0096] S5: Every hour of construction, a modulus identification is performed once to update the layered compensation model parameters under the condition that the lifting cylinder supports the weight of the milling head, the winch releases the main load, and the wire rope is kept under slight tension. Every 8 hours of construction, a system zero-point calibration is automatically performed to eliminate drift errors caused by long-term operation and maintain micron-level feed accuracy.

[0097] This method first eliminates equipment installation errors, mechanical backlash, and initial temperature drift at the source through full-stroke calibration of the micro-feed module and zero-point calibration of the sensing unit in step S1, establishing a precise benchmark for subsequent micron-level control. Then, through coarse positioning and initial stiffness benchmark establishment in step S2, precise matching between macroscopic formation characteristics and microscopic cutting parameters is achieved, providing an initial basis for single-tooth level compensation. Finally, through multi-source data synchronous acquisition and parallel computation of single-tooth adjustment, layered compensation, and tooth tip prediction in step S3, the control granularity is refined to the single-tooth cutting cycle, real-time offsetting of hydraulic residual errors, single-tooth elastic rebound, wire rope deformation, and other factors. Micrometer-level deviations caused by tooth tip wear are corrected through a closed-loop correction system based on status feedback, ensuring precise execution of every compensation action. The shock-free mode switching and synchronous reset mechanism in step S4 maintains uninterrupted micro-feed compensation throughout the load handover process between the lifting cylinder and the winch, preventing feed accuracy jumps and construction stoppages caused by mode switching. Step S5, with its hourly online modulus identification and 8-hour system zero-point calibration, dynamically updates the wire rope's elastic properties and eliminates accumulated drift from long-term operation, ensuring the system maintains stable micrometer-level feed accuracy throughout continuous ultra-deep construction for tens of hours.

[0098] This method does not require any modification to the main structure of the original hydraulic system. By simply adding an independent control link, the feed accuracy can be improved from the millimeter level to the micrometer level. This not only significantly improves the flatness of the trench and reduces the verticality error of the trench, but also enhances the impermeability and long-term durability of ultra-deep underground continuous walls. Furthermore, it can extend the service life of the milling wheel cutter and reduce the maintenance cost of the equipment.

[0099] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A micron-level feed servo control system for a dual-wheel milling machine, applied to the micro-feed device of a dual-wheel milling machine, wherein the micro-feed device of the dual-wheel milling machine includes a milling head, a lifting cylinder, a winch, a wire rope, and an intermediate pulley, characterized in that, It includes a sensing unit, an analysis unit, a decision-making unit, and an execution unit that are connected in sequence via communication. The sensing unit is configured to collect the actual displacement of the milling head, the torque fluctuation and temperature drift data of the single tooth cutting of the milling wheel, and generate a multi-source dataset; The analysis unit includes an adjustment module and a compensation module. The adjustment module is used to output the single-tooth level elastic rebound compensation amount, and the adjustment module has built-in stiffness identification logic and single-tooth adjustment logic. The compensation module is used to output the residual deformation compensation amount of the wire rope and the wear compensation amount of the milling wheel tooth tip, and the compensation module has built-in layered compensation logic and tooth tip prediction logic. The decision-making unit includes a collaborative control module for generating three-level feed collaborative control commands. The collaborative control module has built-in normal collaborative logic, switching collaborative logic, and abnormal collaborative logic. The execution unit includes a micro-feed module and a status feedback module; the micro-feed module is connected in series between the piston rod of the lifting cylinder and the intermediate pulley and is used to perform displacement compensation; the status feedback module is used to collect execution status data and feed it back to the decision unit to form closed-loop control.

2. The dual-wheel milling micron-level feed servo control system according to claim 1, characterized in that, In the stiffness identification logic, the formula for calculating contact stiffness is: .

3. The dual-wheel milling micron-level feed servo control system according to claim 2, characterized in that, The single-tooth adjustment logic is configured to adjust based on the identified contact stiffness. Predict the elastic rebound amount when the next cutting tooth enters. 10ms before the next cutting tooth enters, the micro-feed module is driven to extend by the corresponding length in advance to counteract elastic rebound and ensure that the actual chip thickness is consistent with the theoretical value.

4. The dual-wheel milling micron-level feed servo control system according to claim 3, characterized in that, In the layered compensation logic, the total elastic deformation of the wire rope is decomposed into three independent parts, and the calculation formula is as follows: .

5. The dual-wheel milling micron-level feed servo control system according to claim 4, characterized in that, The compensation module also incorporates equivalent elastic modulus identification logic, which is configured to inject step displacement excitation into the micro-feed module when the lifting cylinder supports the weight of the milling head, the winch releases the main load, and the wire rope maintains a slight pretension. Simultaneously, the tension change of the wire rope is collected. Calculate the equivalent elastic modulus of the current wire rope. The equivalent elastic modulus of the steel wire rope The calculation formula is: .

6. The dual-wheel milling micron-level feed servo control system according to claim 5, characterized in that, In the tooth tip prediction logic, the formula for calculating the cumulative wear is: .

7. The dual-wheel milling micron-level feed servo control system according to claim 1, characterized in that, The normal collaborative logic is configured such that the lifting cylinder is responsible for millimeter-level macro feed and bears the main cutting load, while the micro feed module is responsible for micrometer-level dynamic correction. The switching collaborative logic is configured such that when the lifting cylinder reaches a preset threshold of its maximum stroke to initiate the mode switching process, the micro feed module maintains its current output unchanged, and automatically resets to the midpoint of the stroke after the lifting cylinder has finished switching. During the reset process, the moving speed is synchronized with the lifting cylinder feed speed.

8. The dual-wheel milling micron-level feed servo control system according to claim 7, characterized in that, The abnormal coordination logic is configured such that when the milling wheel torque exceeds the micron-level retraction threshold of the rated torque, the micro-feed module performs a micron-level retraction of 5μm-10μm; if the torque continues to rise and exceeds the millimeter-level retraction threshold of the rated torque, then the lifting cylinder performs a millimeter-level retraction.

9. The dual-wheel milling micron-level feed servo control system according to claim 1, characterized in that, The sensing unit includes a strain ring, a displacement detection module, and a temperature compensation module. The strain ring is sleeved on the spindle end of the milling wheel. The displacement detection module is used to detect the actual micron-level displacement of the milling head and feed it back to the decision unit. The temperature compensation module is used to collect temperature data to compensate for the error of hydraulic oil viscosity drift and thermal expansion and contraction of mechanical structure.

10. A dual-wheel milling micron-level feed servo control method, implemented based on the dual-wheel milling micron-level feed servo control system according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1: After the original hydraulic system completes sensor self-test, communication link detection and actuator calibration, the decision unit drives the micro-feed module to perform full-stroke reciprocating motion, generates command displacement-actual displacement calibration curve, and performs zero-point calibration on the sensing unit to eliminate installation errors and temperature drift. After the self-test is completed, it enters standby mode. S2: The original controller controls the winch and lifting cylinder to complete the coarse positioning of the milling head. The milling wheel cuts into the formation at low speed. The original controller identifies the macroscopic formation type. The analysis unit synchronously collects the initial torque data and establishes the benchmark value of the stiffness identification logic. S3: During normal milling operations, the sensing unit collects single-tooth micro-torque, milling wheel head displacement and temperature data in real time and transmits them to the analysis unit; the analysis unit performs single-tooth adjustment, layered compensation and tooth tip prediction in real time, and outputs the total compensation amount to the decision unit. The decision-making unit generates collaborative control commands to drive the micro-feed module to perform micron-level displacement correction, and the status feedback module feeds back the actual execution status to form a micron-level closed-loop control. S4: When the lifting cylinder reaches the preset threshold of its maximum stroke, the collaborative control module performs a shock-free mode switch, and the micro-feed module maintains its current output. After the switch is completed, the micro-feed module automatically resets to the midpoint of the stroke at a speed synchronized with the feeding speed of the lifting cylinder, preparing for the next round of micro-feed compensation. S5: Every hour of construction, a modulus identification is performed once during the gap when the lifting cylinder supports the weight of the milling head, the winch releases the main load, and the wire rope maintains a slight pre-tension, and the layered compensation model parameters are updated; every 8 hours of construction, a system zero-point calibration is automatically performed to eliminate drift errors caused by long-term operation and maintain micron-level feed accuracy.

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