Hydraulic control system under variable load piling working condition

Abstract

The invention relates to the technical field of engineering machinery control, and discloses a hydraulic control system under a variable load piling working condition, which comprises a multi-dimensional state acquisition module, a fluid parameter observation module, a signal reconstruction decoupling module, a virtual impedance mapping module and a fluid phase locking control module. The acquisition module acquires a basic physical state; the observation module solves the effective volume elastic modulus of the hydraulic oil based on a fluid continuity equation; the reconstruction module utilizes the modulus to correct signal lag, reconstructs external load force through an inverse dynamic model and decouples environmental acoustic impedance; the mapping module dynamically generates a target mechanical impedance parameter according to the environment impedance; and the control module calculates an ideal instruction based on the target parameter, corrects the gain by utilizing the fluid modulus and locks the rebound peak phase to adjust the action time sequence of the valve core. Control distortion caused by fluid parameter drift is solved, active flexible adaptation to variable load geology is achieved, energy hedging is avoided, and operation efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engineering machinery control, in particular to a hydraulic control system under variable load piling conditions. BACKGROUND

[0002] Hydraulic piling equipment is widely used in pile foundation construction of building foundation, port and ocean engineering. In the actual operation process, the geological environment usually has high nonlinearity and uncertainty, and the pile body is easy to frequently switch between different media such as soft soil, sand layer and rock during penetration, resulting in dramatic and random changes in load impedance. In order to ensure the efficiency and safety of piling operation, the hydraulic control system needs to respond quickly and accurately to the changing load.

[0003] However, in the existing hydraulic control technology, hydraulic oil is usually regarded as incompressible or parameter constant transmission medium. In the actual high-frequency impact working condition, the temperature rise and bubble mixing of hydraulic oil will cause the drift of its effective bulk modulus of elasticity, resulting in the enhancement of fluid capacitive effect. The existing technology lacks real-time observation and compensation mechanism for the change of this physical property, and directly uses the pressure sensor signal to represent the external load. Due to the existence of fluid compressibility, the pressure signal collected by the sensor has obvious phase lag and amplitude attenuation relative to the actual geological reaction force received by the pile head. This signal distortion makes it difficult for the control system to accurately identify the current geological characteristics, and easy to cause the control strategy to fail due to signal misjudgment.

[0004] In addition, the traditional hydraulic piling control strategy mostly adopts constant power or fixed parameter PID control, and once the dynamics characteristics (such as stiffness and damping) of the system are set, they are difficult to adjust in real time. When facing the complex geology of alternating soft and hard, the control strategy with fixed stiffness is difficult to meet the needs of different working conditions. If the system stiffness is set too high, when encountering strong elastic rebound of high impedance rock layer, the hydraulic system cannot show flexible retreat, resulting in huge impact energy directly acting on the mechanical structure, causing equipment damage; if the system stiffness is set too low, it cannot provide enough penetration driving force when working in soft soil layer, resulting in low operation efficiency. The mismatch between this inherent characteristics of the system and the variable environment load limits the adaptability of the equipment.

[0005] Meanwhile, the prior art mainly focuses on the size of the output power in energy management, ignores the phase matching problem of the hydraulic energy release timing and the load dynamic response, and does not consider the influence of fluid parameter changes on the control bandwidth. When the hydraulic oil becomes soft and the pressure build-up time is prolonged, the fixed gain controller cannot compensate for the response delay, resulting in a decline in system dynamic performance. More importantly, the lack of phase management of the control output is easy to overlap with the elastic rebound wave of the pile body, resulting in mutual cancellation of the hydraulic driving force and the geological rebound force, which not only causes serious energy waste, but also easily excites severe oscillation of the system, affecting the stability of the operation. SUMMARY

[0006] In view of the shortcomings of the prior art, the present application provides a hydraulic control system under variable load piling conditions, which solves the problems of load identification signal distortion caused by ignoring the parameter drift of the hydraulic medium, equipment damage or low efficiency caused by the fixed stiffness control strategy unable to adapt to soft and hard alternating geology, and low energy utilization and response delay caused by the lack of phase and gain compensation.

[0007] The present application provides a hydraulic control system under variable load piling conditions, which aims to solve the problems of control distortion and low energy transmission efficiency caused by parameter drift of the hydraulic medium in the existing hydraulic piling equipment under complex geological environment.

[0008] The hydraulic control system under variable load piling conditions provided by the present application comprises a multi-dimensional state acquisition module, a fluid parameter observation module, a signal reconstruction decoupling module, a virtual impedance mapping module and a fluid phase-locked control module.

[0009] The multi-dimensional state acquisition module is used to obtain the basic physical state of the hydraulic piling equipment. It accesses the physical sensors of the hydraulic piling equipment, controls the high-frequency A / D converter to synchronously sample the real-time pressure of the rodless cavity of the hydraulic cylinder, the real-time pressure of the rod cavity of the hydraulic cylinder, the real-time displacement of the hydraulic cylinder piston rod and the displacement of the main valve core. This module ensures that the pressure signal and the displacement signal are aligned on the time axis through a synchronization mechanism, and removes high-frequency noise using a digital low-pass filter to generate state variables containing the above physical quantities.

[0010] The fluid parameter observation module is used to monitor the changes of the physical properties of the hydraulic medium in real time. The module receives the state variables, first determines the instantaneous flow into the rodless cavity according to the displacement of the main valve core and the real-time pressure of the rodless cavity of the hydraulic cylinder, and combines the valve port flow characteristics.

[0011] Subsequently, the module establishes a comparison relationship between the pressure gradient and the net flow difference based on the fluid continuity equation, obtains the net compression flow by subtracting the leakage flow from the instantaneous flow minus the volume change rate term, and combines the current total volume and the time differential of the rodless chamber pressure to inversely solve the effective bulk modulus of the hydraulic oil, thereby realizing real-time calculation of the compression characteristics of the hydraulic oil.

[0012] The signal reconstruction decoupling module is used to restore the real external load and identify geological features. The module uses the effective bulk modulus as a fluid stiffness correction factor to dynamically phase correct the real-time pressure of the rodless chamber of the hydraulic cylinder, compensating for the signal lag caused by oil compression. On this basis, the module establishes an inverse dynamics model to calculate the reconstructed external load force by calculating the total driving force of the hydraulic cylinder and subtracting the inertial force term, viscous friction force term, and coulomb friction force term of the piston assembly, eliminating the influence of fluid capacitance and mechanical inertia.

[0013] Further, the module analyzes the waveform characteristics of the reconstructed external load force using one-dimensional wave theory, determines the impedance type of the current working condition according to the rising edge slope and wave crest shape characteristics of the waveform, and outputs the quantified environmental acoustic impedance.

[0014] The virtual impedance mapping module is used to determine the target dynamics characteristics of the system. The module establishes an adaptive correlation between the environmental acoustic impedance and the target mechanical impedance parameters based on a pre-set nonlinear mapping function table.

[0015] When the environmental acoustic impedance changes, the module dynamically adjusts the virtual mass, virtual damping, and virtual stiffness, for example, reduces the virtual stiffness and increases the virtual damping when the environmental acoustic impedance increases, to achieve impedance complementation.

[0016] The fluid phase lock control module is used to generate the final execution instruction. The module receives the real-time displacement of the hydraulic cylinder piston rod, the reconstructed external load force, the target mechanical impedance parameters, and the pre-set ideal pile driving trajectory. At the control operation level, the module uses the virtual stiffness, virtual damping, and virtual mass in the target mechanical impedance parameters to respectively weight and sum the position error, velocity error, and acceleration error between the ideal pile driving trajectory and the real-time motion state, and adds the reconstructed external load force as a feedforward term to calculate the ideal hydraulic output instruction.

[0017] At the instruction execution level, the module performs fluid parameter compensation and phase locking: on the one hand, it uses the effective bulk modulus to calculate the flow gain correction coefficient, and increases the gain when the effective bulk modulus decreases to compensate for the response lag; on the other hand, it monitors the rebound wave crest of the reconstructed external load force, and forcibly adjusts the action timing of the spool control instruction to make the phase of the generated hydraulic pressure pulse and the phase of the rebound wave crest maintain a pre-set avoidance phase difference, and finally generates the spool control instruction for driving the valve group.

[0018] The present application provides a kind of hydraulic control system under the variable load piling condition.Work with the following beneficial effects: 1, the present application establishes the parameter observation mechanism based on fluid continuity equation, realizes the real-time identification of the effective volume elastic modulus of hydraulic oil, and applies it to the inverse dynamics reconstruction of load signal.The technical scheme eliminates the fluid capacitance effect caused by the increase of gas content or the increase of temperature of hydraulic oil, solves the phase lag and amplitude distortion problem of pressure sensor signal relative to real load, so that the system can accurately decouple the environmental acoustic impedance from the mixed sensor data under complex variable load conditions, ensure the reliability of geological feature identification, and avoid control misjudgment caused by medium physical property drift.

[0019] 2, the present application realizes the adaptive adjustment of the dynamics characteristics of hydraulic system through virtual impedance mapping.The system can dynamically adjust the virtual stiffness, virtual damping and virtual mass parameters according to the identified environmental impedance characteristics.When encountering high impedance rock layer, the system automatically reduces the virtual stiffness and increases the damping, presents flexible characteristics to absorb the rebound impact, and protects the mechanical structure;When in low impedance soft soil layer, the system increases the virtual stiffness to ensure the tracking accuracy of the penetration trajectory, effectively overcomes the problem of rigid impact damage to equipment or low penetration efficiency of traditional constant stiffness control in alternating hard and soft geology.

[0020] 3, the present application adopts fluid phase lock control strategy, combines feedforward compensation of fluid parameters and waveform phase management, adjusts valve port flow gain according to effective volume elastic modulus in real time, suppresses the control response bandwidth attenuation caused by softening of oil, and maintains the dynamic performance of high frequency piling.At the same time, by locking the rebound peak of reconstructed load force and adjusting the timing of spool action, the output phase of hydraulic pressure and the phase of geological rebound wave keep away from each other, avoid the direct offset of hydraulic energy and elastic potential energy, improve the energy utilization efficiency and reduce the risk of system oscillation. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a hydraulic control system architecture diagram under the variable load piling condition of the present application; Figure 2 It is a fluid parameter observation module architecture diagram of the present application; Figure 3 It is a signal reconstruction decoupling module architecture diagram of the present application.

[0022] Among them, 100, multi-dimensional state acquisition module;200, fluid parameter observation module;300, signal reconstruction decoupling module;400, virtual impedance mapping module;500, fluid phase lock control module. DETAILED DESCRIPTION

[0023] With reference to the drawings of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described, obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0024] Please refer to the drawings of the present application Figure 1 The embodiment of the present application provides a hydraulic control system under variable load piling conditions, which is applied to a hydraulic piling device under variable load conditions. The system is connected with physical sensors and execution elements of the hydraulic system through a controller, and the physical sensors include a hydraulic cylinder rodless cavity pressure sensor, a hydraulic cylinder rod cavity pressure sensor, a hydraulic cylinder piston rod displacement sensor and a main valve core displacement sensor.

[0025] The system includes a multi-dimensional state acquisition module 100, a fluid parameter observation module 200, a signal reconstruction decoupling module 300, a virtual impedance mapping module 400 and a fluid phase-locked control module 500.

[0026] The multi-dimensional state acquisition module 100 is connected with the physical sensors of the hydraulic system, and is used to obtain the basic physical state of the hydraulic system.

[0027] The multi-dimensional state acquisition module 100 uses a high-frequency A / D converter to synchronously sample and filter the physical sensor signals, and generates denoised state variables. The state variables output by the multi-dimensional state acquisition module 100 include the real-time pressure of the hydraulic cylinder rodless cavity , the real-time pressure of the hydraulic cylinder rod cavity , the real-time displacement of the hydraulic cylinder piston rod and the displacement of the main valve core .

[0028] The multi-dimensional state acquisition module 100 transmits the real-time pressure of the hydraulic cylinder rodless cavity , the real-time displacement of the hydraulic cylinder piston rod and the displacement of the main valve core to the fluid parameter observation module 200, transmits the real-time pressure of the hydraulic cylinder rodless cavity , the real-time pressure of the hydraulic cylinder rod cavity and the real-time displacement of the hydraulic cylinder piston rod to the signal reconstruction decoupling module 300, and transmits the real-time displacement of the hydraulic cylinder piston rod to the fluid phase-locked control module 500.

[0029] The fluid parameter observation module 200 receives the state variables from the multi-dimensional state acquisition module 100, and is used to monitor the changes of the physical properties of the hydraulic medium.

[0030] The fluid parameter observation module 200 calculates the effective bulk modulus of hydraulic oil according to the master valve core displacement and the real-time pressure of the rodless chamber of the hydraulic cylinder , calculates the instantaneous flow into the rodless chamber , and based on the fluid continuity equation, uses the instantaneous flow , the real-time speed of the hydraulic cylinder piston rod , and the time differential of the rodless chamber pressure to inversely calculate the effective bulk modulus of hydraulic oil .

[0031] The fluid parameter observation module 200 calculates the effective bulk modulus of hydraulic oil through a fluid modulus estimation formula , which is as follows: ; wherein: is the effective bulk modulus of hydraulic oil; is the initial dead volume of the rodless chamber of the hydraulic cylinder; is the effective piston area of the rodless chamber of the hydraulic cylinder; is the real-time displacement of the hydraulic cylinder piston rod; is the instantaneous flow into the rodless chamber; is the real-time speed of the hydraulic cylinder piston rod; is the total leakage coefficient of the hydraulic cylinder; is the real-time pressure of the rodless chamber of the hydraulic cylinder; is the time differential of the rodless chamber pressure.

[0032] The effective bulk modulus of hydraulic oil output by the fluid parameter observation module 200 is respectively transmitted to the signal reconstruction decoupling module 300 and the fluid phase-locked control module 500.

[0033] The signal reconstruction decoupling module 300 receives the state variables from the multi-dimensional state acquisition module 100 and the effective bulk modulus of hydraulic oil from the fluid parameter observation module 200 , for restoring the external load and identifying environmental characteristics.

[0034] The signal reconstruction decoupling module 300 uses the effective bulk modulus of hydraulic oil to establish an inverse dynamic model containing fluid capacitive compensation, dynamically corrects the real-time pressure of the rodless chamber of the hydraulic cylinder , and calculates the reconstructed external load force after eliminating the influence of fluid compression hysteresis . The signal reconstruction decoupling module 300 calculates the reconstructed external load force through a load signal reconstruction formula, which is as follows: ; wherein: is the reconstructed real external load force; is the real-time pressure of the rodless chamber of the hydraulic cylinder; is the effective piston area of the rodless chamber of the hydraulic cylinder; is the real-time pressure of the rod chamber of the hydraulic cylinder; is the effective piston area of the rod chamber of the hydraulic cylinder; is the physical mass of the piston and the pile hammer assembly; is the real-time acceleration of the piston rod of the hydraulic cylinder; is the viscous friction coefficient inside the hydraulic cylinder; is the real-time velocity of the piston rod of the hydraulic cylinder; is the Coulomb friction amplitude; is the sign function.

[0035] The signal reconstruction decoupling module 300 analyzes the rising edge slope and the wave crest shape of the reconstructed external load force by using one-dimensional wave theory, decouples and outputs the quantized environmental acoustic impedance . The signal reconstruction decoupling module 300 transmits the environmental acoustic impedance to the virtual impedance mapping module 400, and transmits the reconstructed external load force to the fluid phase-locked control module 500.

[0036] The virtual impedance mapping module 400 receives the environmental acoustic impedance from the signal reconstruction decoupling module 300, for determining the target dynamic characteristics of the system.

[0037] The virtual impedance mapping module 400 dynamically matches and generates target mechanical impedance parameters including virtual mass , virtual damping and virtual stiffness according to a preset nonlinear mapping function table and the current environmental acoustic impedance .

[0038] The virtual impedance mapping module 400 transmits the virtual mass , virtual damping and virtual stiffness to the fluid phase-locked control module 500.

[0039] The fluid phase-locked control module 500 receives the real-time displacement of the piston rod of the hydraulic cylinder , the effective bulk modulus , the reconstructed external load force and the target mechanical impedance parameters from the previous modules, for generating the final control instruction.

[0040] The fluid phase lock control module 500 adopts an impedance control algorithm, uses virtual mass , virtual damping , virtual stiffness , trajectory error and reconstructed external load force to calculate ideal hydraulic output command .

[0041] The fluid phase lock control module 500 calculates the ideal hydraulic output command through a virtual impedance control formula, and the virtual impedance control formula is as follows: ; In the formula: is the ideal hydraulic output command calculated by the controller; is the reconstructed real external load force; is the virtual mass; is the target acceleration of the preset ideal trajectory; is the real-time acceleration of the hydraulic cylinder piston rod; is the virtual damping; is the target speed of the preset ideal trajectory; is the real-time speed of the hydraulic cylinder piston rod; is the virtual stiffness; is the target position of the preset ideal trajectory; is the real-time displacement of the hydraulic cylinder piston rod.

[0042] The fluid phase lock control module 500 uses the effective volume elastic modulus to feed forward correct the valve port flow gain, and according to the waveform characteristics of the reconstructed external load force , locks the valve core action timing, converts the ideal hydraulic output command into a valve core control command , and drives the execution valve group of the hydraulic system.

[0043] The multi-dimensional state acquisition module 100 is mainly responsible for establishing the signal link between the control system and the hydraulic physical entity, realizing the conversion of physical quantities to digital state variables and time sequence alignment. The input end of the multi-dimensional state acquisition module 100 is physically connected to the sensor group of the hydraulic pile driver, and the sensor group specifically includes a pressure sensor installed on the rodless cavity oil port of the hydraulic cylinder, a pressure sensor installed on the rod cavity oil port of the hydraulic cylinder, a magnetostrictive displacement sensor (or a grating ruler) integrated in the hydraulic cylinder or outside the hydraulic cylinder, and a valve core displacement sensor (LVDT) integrated on the main control valve.

[0044] As for the selection and installation method of the above-mentioned sensors, those skilled in the art can select industrial-grade sensors with corresponding range and accuracy according to actual working condition requirements, which belongs to the known technology in the art, and will not be described here.

[0045] The multi-dimensional state acquisition module 100 is internally provided with a state data acquisition unit, which is configured with a high-frequency A / D converter (analog-to-digital converter). Considering that the stress wave propagation speed is very fast under the piling working condition (usually about 5000 m / s in steel and about 1200-1400 m / s in oil), in order to capture the transient pressure fluctuation characteristics, the state data acquisition unit sets the sampling frequency to be higher than 10 times of the highest mechanical response frequency of the system, for example, a sampling rate of 1 kHz to 10 kHz. The state data acquisition unit controls the A / D converters of all channels to perform synchronous sampling under the trigger of the same clock pulse, so as to ensure that the acquired pressure signals and displacement signals are strictly aligned on the time axis, and avoid phase errors caused by channel scanning delay. This timing synchronization processing is the basis for subsequent phase-locked control.

[0046] After obtaining the original analog signals, the state data acquisition unit performs filtering processing on the signals. For the common electromagnetic interference and pump pulsation noise of the hydraulic system, the state data acquisition unit uses a digital low-pass filter (such as an infinite impulse response IIR filter or a finite impulse response FIR filter) to denoise the original data. The setting of the filter cutoff frequency needs to retain the high-frequency stress wave characteristics caused by the geological rebound, while filtering out the high-frequency electrical noise.

[0047] After the above sampling and filtering processing, the multi-dimensional state acquisition module 100 outputs a series of denoised state variables, including: Real-time pressure of the rodless cavity of the hydraulic cylinder , representing the fluid pressure state of the driving side; Real-time pressure of the rod cavity of the hydraulic cylinder , representing the fluid pressure state of the oil return side or back pressure side; Real-time displacement of the hydraulic cylinder piston rod , representing the motion position of the actuator; Main valve core displacement , representing the actual opening degree of the control valve port.

[0048] The above state variables serve as the reference input for subsequent system calculation, wherein 、 、 are transmitted to the fluid parameter observation module 200 for parameter identification; 、 、 are transmitted to the signal reconstruction and decoupling module 300 for mechanical model reconstruction; are transmitted to the fluid phase-locked control module 500 for forming a position closed loop.

[0049] Referring to the accompanying Figure 2The fluid parameter observation module 200 constructs a real-time observer for the physical properties of the hydraulic medium to solve the problem of bulk modulus drift caused by hydraulic oil gas mixing and temperature rise in pile driving. The fluid parameter observation module 200 is mainly composed of an instantaneous flow estimation unit and a modulus reverse calculation unit, and the fluid compression characteristics under the current working condition are deduced by reverse derivation through the fluid dynamics equation.

[0050] The fluid parameter observation module 200 first calculates the theoretical flow into the rodless cavity of the hydraulic cylinder using the instantaneous flow estimation unit. The instantaneous flow estimation unit receives the main valve core displacement and the real-time pressure of the rodless cavity of the hydraulic cylinder from the multi-dimensional state acquisition module 100.

[0051] Based on the throttling principle of the slide valve, the valve port flow is proportional to the square root of the valve core displacement and the pressure difference of the valve port. The instantaneous flow estimation unit internally stores the flow characteristic curve or flow equation of the main control valve obtained by pre-calibration, determines the valve port flow area according to the current main valve core displacement , and calculates the pressure difference of the valve port in combination with the system oil supply pressure and the current , and then calculates the instantaneous flow into the rodless cavity . For the oil supply pressure signal, a constant value can be used, or a pump outlet pressure sensor can be added to obtain it in real time.

[0052] After obtaining the instantaneous flow data, the modulus reverse calculation unit performs parameter calculation based on the fluid continuity equation. The fluid continuity equation is a basic law describing the conservation of mass of fluid in the control volume, which shows that the net flow into the control volume is equal to the sum of the flow term caused by volume expansion, the flow term caused by fluid compression, and the leakage flow term.

[0053] The conventional control strategy usually assumes that the fluid is incompressible or the elastic modulus is constant, but in the variable load working condition of the present application, the modulus reverse calculation unit regards the effective bulk modulus as a time-varying state variable to be observed. The modulus reverse calculation unit performs differential operation on the real-time displacement of the hydraulic cylinder piston rod provided by the multi-dimensional state acquisition module 100 to obtain the real-time speed , and performs differential operation on the real-time pressure to obtain the time differential of the rodless cavity pressure .

[0054] The modulus reverse calculation unit transforms the fluid continuity equation into an explicit expression for the elastic modulus, and uses the comparison relationship between the pressure gradient and the net flow difference to calculate the effective bulk modulus of the hydraulic oil in real time . The calculation process is realized through the fluid modulus estimation formula, which is as follows: ; wherein: is the effective bulk modulus of the hydraulic oil, which parameter synthetically reflects the mixed compression stiffness of the pure liquid phase of the hydraulic oil and the bubbles mixed inside it; is the initial dead volume of the rodless chamber of the hydraulic cylinder, which refers to the inherent volume of the chamber and the connecting pipeline when the piston is in the fully retracted state; is the effective piston area of the rodless chamber of the hydraulic cylinder; is the real-time displacement of the piston rod of the hydraulic cylinder, represents the total volume of the rodless chamber at the current moment; is the instantaneous flow entering the rodless chamber; is the real-time speed of the piston rod of the hydraulic cylinder, represents the volume change rate caused by the piston movement; is the total leakage coefficient of the hydraulic cylinder, which is a constant obtained through offline calibration or an empirical value; is the real-time pressure of the rodless chamber of the hydraulic cylinder; is the time differential of the pressure of the rodless chamber, which represents the dynamic rate of pressure establishment or release.

[0055] Through the above calculation, the fluid parameter observation module 200 realizes the digital observation of the compression characteristics of the hydraulic system.

[0056] The effective bulk modulus of elasticity output by the fluid parameter observation module 200 is transmitted to the signal reconstruction decoupling module 300 for compensating for the pressure wave propagation lag caused by the decrease in oil stiffness at the signal processing level. At the same time, is also transmitted to the fluid phase-locked control module 500 for adjusting the open-loop gain at the control execution level to prevent the control response from being sluggish due to the decrease in oil stiffness. This real-time parameter observation mechanism based on physical equations ensures that the system can still maintain the accuracy of the mathematical model in the harsh piling site where the gas content of the oil fluctuates sharply. Referring to the accompanying drawings,

[0057] the signal reconstruction decoupling module 300 is used to eliminate the interference of the dynamic characteristics of the hydraulic transmission system on the load signal, restore the real external geological force, and identify the acoustic impedance characteristics of the environment accordingly. The signal reconstruction decoupling module 300 receives the real-time pressure Figure 3 of the rodless chamber of the hydraulic cylinder, the real-time pressure of the rod chamber of the hydraulic cylinder, the real-time displacement of the piston rod of the hydraulic cylinder, and the effective bulk modulus of elasticity from the fluid parameter observation module 200.

[0058] The signal reconstruction decoupling module 300 first performs signal processing through the built-in force signal de-distortion unit. In the high-frequency impact process of hydraulic pile driving, the pressure signal measured by the sensor is actually the superposition of external geological load, inertial force of the piston assembly, friction force of the seal, and fluidic capacity effect of the hydraulic oil.

[0059] In order to obtain an accurate external geological load, the force signal de-distortion unit establishes an inverse dynamics model containing fluidic capacity compensation. The model uses the effective bulk modulus calculated by the pre-sequencing module As a fluid stiffness correction factor, the pressure signal is phase-aligned on the time axis, compensating for the pressure wave propagation delay caused by oil compression, and ensuring the synchronization of pressure variables and motion variables at the physical action time.

[0060] After completing the phase correction, the force signal de-distortion unit separates the inertial term and the damping friction term of the piston assembly from the total hydraulic pressure based on the force balance principle of Newton's second law. The force signal de-distortion unit calculates the reconstructed external load force , through the load signal reconstruction formula as follows: ; In the formula: is the reconstructed real external load force, representing the actual force at the contact interface between the pile head and the geology; is the real-time pressure of the rodless cavity of the hydraulic cylinder; is the effective piston area of the rodless cavity of the hydraulic cylinder; is the real-time pressure of the rod cavity of the hydraulic cylinder; is the effective piston area of the rod cavity of the hydraulic cylinder; represents the total driving force output by the hydraulic cylinder; is the physical mass of the piston and pile hammer assembly; is the real-time acceleration of the hydraulic cylinder piston rod, obtained by twice differentiating the real-time displacement ; represents the inertial force consumed by the accelerated motion of the piston assembly; is the viscous friction coefficient inside the hydraulic cylinder, which is proportional to the speed of motion; is the real-time speed of the hydraulic cylinder piston rod; is the Coulomb friction amplitude, representing the dry friction force between the seal and the cylinder barrel; is a sign function, used to determine the direction of the friction force opposite to the speed direction.

[0061] After obtaining the reconstructed external load force , the signal reconstruction decoupling module 300 uses the impedance characteristic decoupling unit to identify the environmental characteristics. The impedance characteristic decoupling unit, based on one-dimensional wave theory, regards the pile driving system as an elastic waveguide, and calculates the reconstructed external load force The stress wave signal considered to propagate along the pile body. Impedance feature decoupling unit The time-domain waveform of the impedance feature decoupling unit is subjected to feature extraction, and the rising slope of the waveform (i.e., the first-order derivative of force with respect to time ) and the energy form of the wave peak are mainly calculated.

[0062] The impedance feature decoupling unit is internally preset with a geological impedance discrimination logic: When the rising slope of the waveform exceeds a preset high-frequency threshold (set according to stress wave reflection test data of different geological samples), and the wave peak form is sharp and the pulse width is narrow, it is determined that the reflection wave is mainly generated by a medium with a high elastic modulus, indicating that the current geology is a rock layer or a hard soil layer, and the system calculates a relatively high environmental acoustic impedance . When the rising slope of the waveform is gentle, and the wave peak form is smooth and the pulse width is wide, it is determined that the reflection wave is mainly generated by a high-damping medium, indicating that the current geology is a soft soil layer or a silt layer, and the system calculates a relatively low environmental acoustic impedance .

[0063] Through the above processing, the signal reconstruction decoupling module 300 decouples the originally mixed sensor data into two independent key variables: the reconstructed external load force representing the true force state, and the environmental acoustic impedance representing the environmental properties. Among them, is transmitted to the virtual impedance mapping module 400 for decision control strategy, is transmitted to the fluid phase lock control module 500 for force control closed loop.

[0064] The virtual impedance mapping module 400 as the core control parameter generation module of the system is responsible for dynamically adjusting the mechanical impedance characteristics presented by the hydraulic execution end according to the current geological environmental characteristics. The virtual impedance mapping module 400 receives the environmental acoustic impedance from the signal reconstruction decoupling module 300, and establishes an adaptive correlation between the environmental impedance and the controller parameters through the built-in impedance parameter mapping unit.

[0065] The core task of the virtual impedance mapping module 400 is to solve the matching problem between the inherent stiffness of the hydraulic system and the variable geological load.

[0066] The impedance parameter mapping unit internally stores a nonlinear mapping function table or a parameter correlation database, which is obtained by fitting experimental test data and defines the correlation between the environmental acoustic impedance and the target mechanical impedance parameters (including the virtual mass , the virtual damping and virtual stiffness ) between them. The design of this mapping relationship follows the principle of impedance complementarity, i.e. the output impedance of the hydraulic system should change inversely with the environmental impedance to maintain the stability of the system contact force.

[0067] The impedance parameter mapping unit adjusts the virtual mass , virtual damping and virtual stiffness according to the received environmental acoustic impedance .

[0068] The virtual stiffness is reduced so that the hydraulic system shows stronger compliance in the control logic, allowing the piston to produce appropriate retreat displacement when it bounces off hard objects, thereby avoiding the destructive pressure impact caused by rigid confrontation. The virtual damping is increased, which increases the system's ability to dissipate high-frequency oscillation energy, helping to quickly attenuate mechanical vibrations caused by bouncing.

[0069] Conversely, when the pile driver is in low impedance geology (such as silt or soft clay), i.e. the value of the virtual stiffness is reduced, and the virtual damping is increased.

[0070] The virtual stiffness is increased so that the hydraulic system shows stronger rigidity, ensuring that the piston rod can strictly follow the preset displacement trajectory, ensuring the impact depth and penetration efficiency. The virtual damping is reduced, which reduces the viscous resistance during movement, which is conducive to efficient energy transfer.

[0071] For the mapping of virtual mass , the impedance parameter mapping unit usually sets it to a reference value matched with the physical inertia of the hydraulic cylinder and the pile hammer, but in high-frequency impact working conditions, it can also be fine-tuned according to the frequency characteristics of to correct the dynamic response bandwidth of the system.

[0072] After the above logical operations, the virtual impedance mapping module 400 outputs the target mechanical impedance parameters (virtual mass , virtual damping and virtual stiffness containing the optimal dynamics at the current time.). These parameters are transmitted to the fluid phase lock control module 500 as core gain coefficients in the impedance control algorithm, guiding the controller to generate the final force control instruction.

[0073] Through this mechanism, the system realizes flexible adaptive control without changing the physical hardware structure.

[0074] The fluid phase lock control module 500 is the execution level control module of the system, responsible for converting the decision parameters generated by the previous modules into physical control signals for driving the electro-hydraulic servo valve.

[0075] The fluid phase lock control module 500 receives the real-time displacement of the hydraulic cylinder piston rod from the multi-dimensional state acquisition module 100 , the effective volume elastic modulus from the fluid parameter observation module 200 , the reconstructed external load force from the signal reconstruction and decoupling module 300 , and the target mechanical impedance parameters (virtual mass , virtual damping , virtual stiffness ) from the virtual impedance mapping module 400. In addition, the fluid phase lock control module 500 also needs to input the preset ideal pile driving trajectory (the best impact energy curve and operating frequency setting according to the pile driving process requirements), including the target position , target speed and target acceleration .

[0076] The fluid phase lock control module 500 first uses the force control instruction generation unit to perform impedance control calculation. Based on the impedance control algorithm, the force control instruction generation unit models the interaction between the hydraulic actuator and the environment as a second-order spring, mass, and damping system.

[0077] Unlike traditional position control, which only focuses on trajectory tracking error, the force control instruction generation unit introduces the reconstructed external load force as a feedforward term, and combines the virtual impedance parameters to weight the trajectory error, calculating the ideal hydraulic output required to achieve the target impedance characteristics. This calculation process is achieved through the virtual impedance control formula, which is as follows: ; In the formula: is the ideal hydraulic output instruction calculated by the controller, i.e., the resultant force that the hydraulic cylinder should generate at the current time; is the reconstructed real external load force, which is used as direct force feedback to offset external disturbances; is the virtual mass, which determines the response inertia of the system to acceleration error; is the target acceleration of the preset ideal trajectory; This refers to the real-time acceleration of the hydraulic cylinder piston rod. Virtual damping determines the system's ability to suppress velocity errors and is mainly used to dissipate vibration energy. The target speed for the preset ideal trajectory; This refers to the real-time speed of the hydraulic cylinder piston rod. The virtual stiffness determines the strength of the system's restoring force to position errors; The target position for the preset ideal trajectory; This represents the real-time displacement of the hydraulic cylinder piston rod.

[0078] Obtaining the ideal hydraulic output command Subsequently, the fluid phase-locked control module 500 uses the gain correction and phase execution unit to generate the final valve core control command. The gain correction and phase execution unit perform fluid parameter compensation, utilizing the input effective bulk modulus. Feedforward correction is applied to the valve orifice flow gain.

[0079] In hydraulic control theory, the open-loop gain of a system is proportional to the bulk modulus of the hydraulic fluid. When monitoring... When the value decreases (indicating that the oil is mixed with gas or softened due to increased temperature), the gain correction and phase execution unit automatically increases the flow gain coefficient, that is, outputs a larger valve opening command under the same force demand, in order to offset the pressure build-up time lag caused by the increase in fluid compressibility, and ensure that the actual response bandwidth of the system does not decrease with the change of oil state.

[0080] Simultaneously, the gain correction and phase execution unit performs phase locking. This gain correction and phase execution unit continuously monitors the reconstructed external load force. The waveform phase. When the system is in a continuous impact state and encounters high impedance rebound, the gain correction and phase execution unit locks the moment of the rebound wave peak and forcibly adjusts the valve core action sequence to maintain a preset avoidance phase difference between the hydraulic pressure output phase and the load rebound wave phase (set according to the principle of minimizing energy offset, for example, setting the avoidance phase difference to be...). ).

[0081] Specifically, at the moment the pile head rebounds upward, the control valve port quickly switches to unloading or reverse oil flow state to avoid the hydraulic energy and elastic potential energy from clashing.

[0082] Finally, the gain correction and phase execution unit outputs valve core control commands that have undergone fluid stiffness compensation and phase optimization. The command is converted into a current signal to drive the electro-hydraulic servo valve, precisely controlling the flow and direction of hydraulic oil entering and exiting the hydraulic cylinder, thus completing adaptive closed-loop control for variable load conditions.

[0083] In summary, the hydraulic control system under variable load piling conditions provided by the embodiment of the present application solves the control distortion problem caused by the parameter drift of the hydraulic medium under variable load conditions by establishing the correlation mechanism of the physical properties of the fluid and the mechanical control strategy. The system uses the correlation of the fluid continuity equation and the transient pressure gradient to realize online identification of the effective bulk modulus of the hydraulic oil, overcoming the limitations of traditional control methods that treat the fluid medium as a constant parameter.

[0084] Based on the real-time observed fluid parameters, the system constructs an inverse dynamics reconstruction path at the signal processing layer, eliminating the pressure wave signal lag and distortion caused by the fluid capacitance effect, so as to accurately decouple the real external geological impedance characteristics from the mixed sensor data. This signal distortion processing ensures the accuracy of the system in judging "soft soil" and "rock" conditions, avoiding misjudgment caused by the increase of oil gas content.

[0085] At the control execution layer, the system realizes active adjustment of the hydraulic dynamics characteristics through virtual impedance mapping, so that the actuator can automatically exhibit flexible characteristics of low stiffness and high damping when encountering high impedance hard layers, effectively absorbing rebound energy. At the same time, combined with the feedforward gain compensation and phase locking strategy of the fluid parameters, the influence of the oil stiffness reduction on the control bandwidth is eliminated, and the hydraulic impact caused by energy hedging is avoided. This technical solution realizes self-adaptation to complex geological environments without changing the existing hydraulic hardware architecture, improving the energy transfer efficiency and equipment running stability of the piling operation.

Claims

1. A hydraulic control system in a variable load piling operation, characterized by, Comprising: a multi-dimensional state acquisition module for accessing physical sensors to generate state variables including real-time pressure of a rodless chamber of a hydraulic cylinder, real-time pressure of a rod chamber of the hydraulic cylinder, real-time displacement of a piston rod of the hydraulic cylinder, and displacement of a main spool; a fluid parameter observation module for receiving the state variables, calculating instantaneous flow into the rodless chamber, and inversely solving effective bulk modulus of hydraulic oil based on a fluid continuity equation; a signal reconstruction decoupling module for correcting the real-time pressure of the rodless chamber of the hydraulic cylinder using the effective bulk modulus, establishing an inverse dynamics model to calculate reconstructed external load force, and decoupling output quantized environmental acoustic impedance; a virtual impedance mapping module for generating target mechanical impedance parameters according to the environmental acoustic impedance; a fluid phase lock control module for calculating ideal hydraulic output command based on the target mechanical impedance parameters and the state variables, gain correcting using the effective bulk modulus, and generating spool control command to drive an execution valve group according to the reconstructed external load force.

2. The hydraulic control system for a variable load piling operation according to claim 1, wherein, The multi-dimensional state acquisition module comprises: a state data acquisition unit for controlling a high-frequency A / D converter to synchronously sample the real-time pressure of the rodless chamber of the hydraulic cylinder, the real-time pressure of the rod chamber of the hydraulic cylinder, the real-time displacement of the piston rod of the hydraulic cylinder, and the displacement of the main spool, ensuring that the real-time pressure of the rodless chamber of the hydraulic cylinder and the real-time displacement of the piston rod of the hydraulic cylinder are aligned on a time axis, denoising sampled data using a digital low-pass filter, and generating the state variables.

3. The hydraulic control system for a variable load piling operation according to claim 1, wherein, The fluid parameter observation module comprises: an instantaneous flow estimation unit for receiving the displacement of the main spool and the real-time pressure of the rodless chamber in the state variables, determining a valve port flow area and calculating a valve port pressure difference according to a valve port flow equation, and then calculating the instantaneous flow into the rodless chamber; a modulus inverse solving unit for receiving the real-time displacement of the piston rod of the hydraulic cylinder and the real-time pressure of the rodless chamber, respectively performing differential operation to obtain real-time speed of the piston rod of the hydraulic cylinder and time differential of the rodless chamber pressure, and executing a fluid modulus estimation formula to calculate the effective bulk modulus.

4. The hydraulic control system for a variable load piling operation according to claim 3, wherein, The valve port flow equation used in the instantaneous flow estimation unit is constructed based on a proportional relationship between the displacement of the main spool and a square root of the valve port pressure difference; The valve port pressure difference is determined according to a system oil supply pressure obtained in real time by a pump outlet pressure sensor and the real-time pressure of the rodless chamber.

5. The hydraulic control system for a variable load piling operation according to claim 3, wherein, The modulus inverse solving unit specifically comprises, when executing the fluid modulus estimation formula: establishing a comparison relationship between a pressure gradient and a net flow difference value based on a fluid continuity equation, obtaining a net compression flow by subtracting a volume change rate term and a leakage flow term from the instantaneous flow into the rodless chamber, calculating a current total volume using the real-time pressure of the rodless chamber of the hydraulic cylinder and the real-time displacement of the piston rod of the hydraulic cylinder, and finally calculating the effective bulk modulus based on the net compression flow, the current total volume, and the time differential of the rodless chamber pressure.

6. The hydraulic control system for a variable load piling operation according to claim 1, wherein, The signal reconstruction decoupling module comprises: a force signal de-distortion unit configured to receive a real-time pressure of a rodless chamber of the hydraulic cylinder, a real-time pressure of a rod chamber of the hydraulic cylinder, a real-time displacement of a piston rod of the hydraulic cylinder, and an effective bulk modulus, perform phase alignment on the real-time pressure of the rodless chamber of the hydraulic cylinder using the effective bulk modulus as a fluid stiffness correction factor, establish the inverse dynamic model, and execute a load signal reconstruction formula to calculate the reconstructed external load force; an impedance characteristic decoupling unit configured to calculate a rising edge slope of the reconstructed external load force and extract a wave crest morphology, determine that a current working condition is a high impedance condition when the rising edge slope exceeds a preset high frequency threshold and the wave crest morphology presents a sharp characteristic, and output the environmental acoustic impedance corresponding to a high impedance value, or determine that the current working condition is a low impedance condition when the rising edge slope is gentle and the wave crest morphology is smooth, and output the environmental acoustic impedance corresponding to a low impedance value; wherein the preset high frequency threshold is preset according to stress wave reflection test data of different geological samples.

7. The hydraulic control system for a variable load piling operation according to claim 6, wherein, The force signal de-distortion unit specifically includes the following when executing the inverse dynamic model and the load signal reconstruction formula: calculating a product of the real-time pressure of the rodless chamber of the hydraulic cylinder and an effective piston area of the rodless chamber of the hydraulic cylinder, subtracting a product of the real-time pressure of the rod chamber of the hydraulic cylinder and an effective piston area of the rod chamber of the hydraulic cylinder, and obtaining a total driving force of the hydraulic cylinder; calculating a real-time speed of the hydraulic cylinder piston rod and a real-time acceleration of the hydraulic cylinder piston rod using the real-time displacement of the hydraulic cylinder piston rod, calculating an inertial force term of the piston and the pile hammer assembly and the real-time acceleration of the hydraulic cylinder piston rod, and calculating a viscous friction force term and a coulomb friction force term; subtracting the inertial force term, the viscous friction force term, and the coulomb friction force term from the total driving force of the hydraulic cylinder to obtain the reconstructed external load force.

8. The hydraulic control system for a variable load piling operation according to claim 1, wherein, The virtual impedance mapping module includes: an impedance parameter mapping unit configured to, according to a preset nonlinear mapping function table, decrease virtual stiffness and increase virtual damping when the environmental acoustic impedance increases, and generate the target mechanical impedance parameter; wherein the target mechanical impedance parameter includes virtual mass, the virtual damping, and the virtual stiffness, and the preset nonlinear mapping function table is obtained by fitting experimental test data.

9. The hydraulic control system for a variable load piling operation according to claim 1, wherein, The fluid phase lock control module includes: a force control instruction generation unit configured to receive a real-time displacement of the hydraulic cylinder piston rod, the reconstructed external load force, the target mechanical impedance parameter, and an ideal pile driving trajectory, calculate a real-time motion state using the real-time displacement of the hydraulic cylinder piston rod, and execute a virtual impedance control formula in combination with the ideal pile driving trajectory to calculate an ideal hydraulic output instruction; The force control instruction generation unit specifically includes the following when executing the virtual impedance control formula: Calculate position error, velocity error and acceleration error between the ideal pile driving trajectory and the real-time motion state, weight sum the position error, the velocity error and the acceleration error by using virtual stiffness, virtual damping and virtual mass in the target mechanical impedance parameters respectively, and superimpose the reconstructed external load force as a feedforward term to the weighted sum result to obtain the ideal hydraulic output command; The ideal pile driving trajectory is pre-set according to the best blow energy curve and the operation frequency required by the pile driving process.

10. The hydraulic control system for a variable load piling operation according to claim 1, wherein, The fluid phase lock control module further comprises: The gain correction execution unit is used to execute fluid parameter compensation and phase lock, and specifically comprises: The effective bulk modulus is used to calculate the flow gain correction coefficient, and the flow gain correction coefficient is increased when the effective bulk modulus decreases; The waveform phase of the reconstructed external load force is monitored, and the output timing of the ideal hydraulic output command is adjusted when a high impedance rebound wave peak is detected to generate the spool control command; When the gain correction execution unit executes the phase lock, the rebound wave peak occurrence time of the reconstructed external load force is locked, the action timing of the spool control command is forcibly adjusted, the phase of the hydraulic pressure pulse generated by the spool control command is kept at a preset avoidance phase difference from the phase of the rebound wave peak; The preset avoidance phase difference is pre-set according to the energy hedging minimization principle.

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