The dynamic pressure signals of hydraulic systems have the characteristics of nonlinearity, multi-source coupling, and sensitivity to operating conditions. This results in high signal complexity and low feature discernibility, rendering traditional diagnostic methods ineffective. A deep learning diagnostic framework based on multi-sensor collaborative perception is proposed to address these issues. Multiple heterogeneous sensor signals are mapped into a multi-channel input tensor through spatial topology mapping, which preserves independent sensor features while achieving joint representation of multimodal information. A parallel convolutional architecture extracts spatiotemporal features from each channel, and an effective channel attention mechanism enhances fault-sensitive information, optimizing cross-modal features for precise classification. Experimental results show that the proposed method achieves over 95% accuracy in diagnosis of hydraulic pump leakage fault on the UCI standard hydraulic dataset. By introducing transfer learning theory, the pre trained model trained on the UCI standard hydraulic dataset is transferred to the forklift lifting hydraulic system, and the model still maintains an accuracy of 97.65%. These results confirm the model's strong generalization ability across different scenarios and provide an effective solution for fault diagnosis in complex hydraulic systems.

To reduce the overall energy consumption of hydraulic excavators and improve the energy utilization efficiency of the hydraulic system, this study proposes an energy recovery and reuse system for the potential energy of the excavator's boom, utilizing a hydraulic winch and an accumulator. The system recovers gravitational potential energy during boom descent and reuses it to assist in boom lifting, thereby reducing the working pressure of the hydraulic system and decreasing fuel consumption. First, the working principle of the system is elaborated in detail, and a mathematical model of the energy-saving device is established. Next, the system is modeled and simulated using AMESim software. The simulation results demonstrate that the system effectively recovers the gravitational potential energy of the descending boom and assists in boom lifting, achieving an energy-saving efficiency of approximately 55.6%. Finally, an experimental bench is constructed to validate the feasibility and effectiveness of the proposed energy-saving device.

Insufficient control precision is caused by strong nonlinearity in vacuum butterfly valve pressure control systems. A dual-mode switching strategy fusing Active Disturbance Rejection Control (ADRC) and PID control is proposed. The controller utilizes an extended state observer to uniformly estimate and compensate for aggregated disturbances including gas temperature drift, sealing friction, and gas source fluctuations. A pressure error threshold triggering mechanism is designed to activate ADRC exclusively during dynamic processes for rapid overshoot suppression, while automatically switching to lightweight PID control during steady-state operation to maintain precision. Compared with conventional PID control, settling time of proposed method is significantly shortened and overshoot substantially reduced. Compared with single ADRC control, steady-state error is effectively minimized. Under flow disturbances, pressure recovery time is 67% faster than that of PID control, with a steady-state error below 25 Pa. This approach significantly enhances system response speed, precision, and robustness, fully leveraging the cost advantage of butterfly valves. And it provides a high-performance, low-cost vacuum pressure control solution for semiconductor, aerospace, and related fields.

Most domestic diesel generator sets in China use mechanical-hydraulic governors for throttle control. Analyzing the operating principles and characteristics of this mature and reliable governor provides critical reference for domestic independent design initiatives. This study constructs component models such as centrifugal flyweight of the governor in AMESim, and develops a diesel generator set dynamical model in Simulink based on the engine load, throttle opening and speed characteristics. Through AMESim/Simulink co-simulation, the study investigates the dynamic behavior of hydraulic buffer compensation in closed-loop speed regulation and its impact on performance. The results indicate that adding hydraulic buffer compensation effectively reduces both the settling time and speed oscillations of diesel generator sets under diesel generators load variations. This design concept not only applies to mechanical-hydraulic governors but also provides critical insights for the autonomous development of digital electronic governors.

Aimed at the problem that it is difficult to levelling the lifting heavy-duty automatic guided vehicle and there exists the “floating leg” issue during leveling, a four-point support heavy-duty automatic guided vehicle hydraulic leveling system is designed and a position compensation mathematical model of hydraulic leveling system is established. The model consists of a highest-point chasing leveling mathematical model and a position compensation mathematical model. The highest-point chasing leveling model is used to execute the leveling process, and the position compensation mathematical model is used to solve the “floating leg” issue in the process. Based on the designed model, the conventional fuzzy PID control strategy is improved, and an enhanced fuzzy PID controller considering floating legs is proposed. A Simulink-AMESim co-simulation platform is built to validate the proposed strategy. The results show that compared with the conventional fuzzy PID method, the improved controller reduces the maximum tracking error of the lowest-point hydraulic cylinder by 86.59%, effectively alleviating the “floating leg” phenomenon.

The vibration and noise of the bent-axis axial piston motor is investigated by a combination of test and simulation. Firstly, the vibration and noise excitation sources of piston motor are investigated and analyzed according to its structural composition and working principle. Secondly, the modal analysis and harmonic response analysis and calculations are carried out by using the simulation software to get the intrinsic frequency of the piston motor and the frequency curves of vibration-related parameters, and the accuracy of the simulation model and test method is verified with vibration tests.Finally, the noise radiation analysis and simulation of the piston motor is carried out by acoustic-vibration coupling method, and the reasonableness of the simulation results is verified with noise test. It is concluded that the peak frequencies of vibration and noise tests are around 700 Hz, which is highly consistent with the theoretical value of excitation frequency 700 Hz, and also close to the first-order intrinsic frequency 704 Hz of the piston motor shell. It proves that the piston motor system is in resonance at this frequency, and proposes optimization directions for vibration reduction and noise reduction of piston motor structure. This study reveals the main mechanism of the vibration noise of the piston motor and provides a basis for its vibration reduction and noise reduction.

Magnetic fluid seals with large diameter are prone to deformation in the environment with a wide temperature range, resulting in a decrease of its maximum working pressure, which means a decline in its pressure resistance performance. In this research, a pressure resistance formula for magnetic fluid seals with the consideration of temperature effects is derived, and the saturation magnetization of magnetic fluids at different temperatures are measured and the simulation analysis of temperature-structure-magnetic field coupling on magnetic fluid seals with large diameter in a wide temperature range is conducted to address the above problems. The structural deformation of the seal at the temperature range of -60~+80 ℃ is analyzed. Furthermore, the magnetic field distribution after the seal deformation is analyzed and the theoretical pressure resistance values of magnetic fluid seals at different temperatures are calculated.Thereby, the reason for changes of pressure resistance of magnetic fluid seals is clarified, which provides a new design method for magnetic fluid rotary seals with large diameter in a wide temperature range. The sealing experiments verify that the magnetic fluid seals designed using this method meet the sealing design requirements.

In grain storage management, the curved surface structure of silo walls imposes stringent demands on the adhesion performance of wall-climbing robots. These robots must possess sufficient flexibility to adapt to curved surfaces while maintaining adequate rigidity to ensure stable support. We find that when a rigid suction cup is employed on walls with varying curvature, the limited deformation capacity of the suction cup body causes the sponge to adopt a “saddle-shaped” deformation during adhesion, which significantly diminishes the adhesion performance. To address this issue, we optimize the rigid suction cup structure, leading to the design of a semi-rigid suction cup with distributed rigid elements. The adhesion force experiments on various simulated substrates reveal that the rigid suction cup exhibit forces of 205.49 N, 307.56 N and 360.25 N on simulated substrates with curvature radii of 100 mm, 200 mm and 400 mm, respectively. In contrast, the semi-rigid suction cup exhibit slight fluctuations in adhesion force across different curved surfaces, yet maintain a stable overall value around 420 N. This solution achieves a significant enhancement in adhesion performance on complex curved surfaces, effectively reducing the risk of detachment during robot operation, which establishes a reliable foundation for expanding the application of wall-climbing robots in areas such as silos.

In order to provide a simulation model for the excitation current and an integrated testing method for the main steam isolation quick-closing solenoid valve in current nuclear power plants, a mathematical model of mass-spring-damping system for solenoid valve core is first established. The excitation current characteristics of the solenoid valve are then simulated and analyzed. Furthermore, based on the current characteristics principle of the solenoid valve and the LabVIEW measurement and control platform, an integrated testing device is designed. This device is used to test the excitation current characteristics of the main steam isolation quick-closing solenoid valve. The test results show that the difference compared to the motion simulation results does not exceed 15%, indicating the rationality of the hardware and software design of the testing device. This testing method has been applied to the detection of quick-closing solenoid valve for main steam isolation valve of the “Hualong One” reactor unit at unit 5 of the Fuqing Nuclear Power Plant, where multiple practical tests have been carried out. The results meet the expectations, providing data and theoretical support for operation and maintenance of the solenoid valve.

Porous graphite materials significantly influence the performance of porous restrictors, which are key components of aerostatic guideways. This study employs the compressible Darcy-Forchheimer equation to fit experimental data and determine the permeability and inertia coefficients of porous graphite with five different porosities (18%, 17%, 13%, 12%, 11%). A CFD model incorporating these coefficients is established, accurately predicting the flow velocity and pressure drop within the porous medium, with an error margin within 5%. Further analysis under various supply pressures and loading conditions reveals that restrictors made from low-permeability graphite materials exhibit superior load-bearing capacity and gas film stiffness. Specifically, under a supply pressure of 0.45 MPa, the stability of the aerostatic block is significantly enhanced. Based on this research, an experimental platform for an aerostatic guideway with an adjustable gas film thickness is constructed using low-permeability restrictors. The guideway surface straightness is verified using a Keyence laser sensor, achieving better than 2.5 μm/600 mm.

The local temperature of the swash plate increases close to the tempering temperature of the material under the swash plate axial pistion pump slipper pair working condition of high speed and large load. As a result, the residual austenite phase transformation causes the material surface expansion, the formation of static pressure support oil film, the surface hardness and durability decrease and other problems. Based on the premise of improving the friction and wear performance of the axial piston pump friction pair under high speed operation. A comparative analysis between the substitute material and the finished sample through composition analysis, high temperature treatment, friction and wear experiments is conducted. The results show that the average surface hardness of B material is increased by 17.7% compared with the original finished material at room temperature. After being stored at 400 ℃ for 10 h, the surface hardness of B material can still remain above 700 HV, the average maximum surface deformation of no more than 1 μm on the surface, and the average wear is reduced by 5.9% compared to the finished sample. The possibility of substitute material selection for swash plate axial piston pump under high speed operation is verified, which provides a reference for the follow-up research on material selection of swash plate axial piston pump.

The pilot solenoid valve regulates the internal oil flow of the shock absorber by controlling the main valve pressure, thereby affecting the damping force. A reasonable design of pressure-flow characteristics can broaden the range of damping adjustment to meet the needs of different working conditions. In this study, the pressure-flow characteristics of the pilot solenoid valve for an automobile continuous damping control shock absorber are optimized. Firstly, the hydrodynamic model and steady state force model of the oil flowing through each damping hole are established based on the fluid dynamics theory. The relationship between the electromagnetic force and the input current is determined with the electromagnetic magnetic circuit model of electromagnetic theory, and then the hydraulic simulation model is established. Subsequently, with the help of the solenoid valve performance test bench, experimental comparisons are carried out to verify the accuracy of the simulation model. Finally, the key structural parameters affecting the pressure-flow characteristics of the pilot solenoid valve were analysed to determine their importance using full factorial analysis of experimental design, and the key dimensions were optimised using a genetic algorithm, with the optimisation effect improved by 10.14%.

Deflector jet servo valve fault signals are limited and easily affected by noise under complex conditions, resulting in difficult feature extraction. This paper presents a fault diagnosis method combining starfish optimization algorithm-based variational mode decomposition, temporal convolutional network, and a self-attention bidirectional gated recurrent unit network. The starfish optimization algorithm selects variational mode decomposition parameters to improve decomposition accuracy and robustness. Main features are extracted from key intrinsic mode functions based on minimum envelope entropy. These features are entered into a temporal convolutional network and a self-attention-based bidirectional gated recurrent unit network to enhance fault classification. A fault simulation platform and dataset are built, with experiments under typical fault conditions. Results show that the fault recognition accuracy of the method achieves 97.33%, demonstrating strong robustness and high diagnostic performance.

Aimed at the problems of low static accuracy and limited dynamic performance of pump control unit, a fuzzy PID pressure stability control method based on load prediction feedforward compensation is proposed to improve the pressure control capability of the pump control unit. Firstly, mathematical models for the servo motor and fixed displacement pump in the pump control unit are established. Secondly, a load prediction algorithm based on long short-term memory neural network is designed, and we train the model, optimize the hyperparameter setting, calculate the evaluation index and carry out simulation verification. Furthermore, the proposed fuzzy PID control method based on load prediction feedforward compensation is analyzed through simulations. Finally, experimental studies validate the control method's effectiveness. The load prediction model achieves high prediction accuracy confirmed by evaluation metrics. With the use of the load prediction results as feedforward signal input compensation, the error between output pressure and expected pressure under two signal responses is reduced by 72.2% and 71.1% respectively compared with that of traditional PID controllers, enabling high-precision pressure stability control in the pump control unit.

This study addresses control challenges in mold demolding systems under nonlinear and time-varying load conditions. A tracking differential fuzzy PID compound control strategy is proposed to enhance system performance by integrating tracking differentiator technology with fuzzy PID control. The strategy features rapid error signal tracking and dynamic self-tuning of PID parameters. The co-simulation experiments combining AMESim and Simulink validate the proposed method. The results demonstrate significant improvements over conventional PID and fuzzy PID controllers: reduced response lag and steady-state error, enhanced tracking precision under high-frequency noise and superior disturbance rejection against unknown large-load interference. The control strategy maintains stable performance in complex operating environments while achieving faster dynamic response. These findings provide theoretical support for high-precision hydraulic servo control in mold demolding systems, particularly in scenarios requiring robust adaptability to nonlinear disturbances. The proposed method offers a practical solution for optimizing industrial mold demolding processes with time-varying dynamics.

In order to enhance the linear regulation capability of solenoid high-speed switching valves and achieve precise control of brake fluid flow, an influence factor characterizing the radial force on axial force of valve core is proposed. The numerical simulation of the internal flow field in the apply valve is carried out, additionally, it is found that the existing structure of valve seat and spool significantly affects brake fluid jet characteristics under Coanda Effect, coupled with asymmetric outlet geometry. These factors collectively increase the vortex probability and instability of flow field in the throttling region, which inducing substantial radial force during the opening and closing cycles. Structure optimization is implemented by reducing the spool spherical throttle ineffective area, implementing of variable-cone-angle surfaces on the valve seat and incorporating symmetrical supplementary outlet ports to improve flow field symmetry. The results show that the flow field of throttle area in new structure is more stable, the radial force on the spool is 0.1 N or less, which is with the opposite direction of the bias and is conducive to self-alignment of the spool. Finally, the new structure effectively weakening the radial force's impact on the linear regulation, reliability and life of the solenoid valve.

In order to reduce the power losses in construction machinery, a novel variable displacement opposed piston pump is proposed. The pump adds a piston on the basis of the traditional single-plunger pump, and the two pistons are arranged symmetrically, which not only attenuates the pressure fluctuation and eliminates the unbalance force of the single-plunger pump, but also realises variable displacement by adjusting the phase difference of the pistons. An AMESim model of the pump is developed and calibrated via equivalent modeling. The lag time of the distribution valve of this pump is compared with that of the traditional piston pump, and it is found that the lag time is relatively less, but there still exists a lag phenomenon, which led to a decrease in the performance of the pump, so the influence of different parameters of the inlet valve on the lag time of the distribution valve is comparatively analysed and the parameters are optimized using the orthogonal method. The results show that: the inlet valve parameters all have a greater impact on the inlet valve closing lag time, which is manifested as with the increase of spring stiffness, spring preload, spool diameter, respectively, the closing lag time is decreased by 10.9, 10.72, 1.73 ms, and is increased by 5.7 ms with the increase of spool mass; after parameter normalisation, the closing lag time of the outlet valve is decreased by 61.6%, 84.1%, and 8.9% with the increase of spring stiffness, spring preload, and spool diameter, respectively, with the increase of spool mass increasing by 37.1%. After orthogonal optimisation, the lag time of the outlet valve closure of the simulation model is decreased by 81.43%, which effectively reduces the return loss and improves the performance of the pump.

Slipper wear is a common failure in piston pumps. Aimed at the failures of the flow rate decrease and excessive vibration of the pump caused by slipper wear in the fuel piston pump of a certain type of aero-engine, a comprehensive failure diagnosis method is proposed within the framework of multiple disciplines including dynamics, tribology, fluid lubrication, and structural strength. The calculation and simulation of the oil film thickness, structural strength, and pv value of the slipper of this type of fuel piston pump under multiple operating conditions are carried out, and the associated mechanism between each operating condition and the wear failure is analyzed. The research results show that the structural strength of the slipper of the fuel piston pump meets the requirements within the full operating condition range, and the oil film characteristics are favorable when the rotational speed is below 4500 r/min. However, when the rotational speed of the fuel piston pump gradually increases, the proportion of the axial inertial force and centrifugal force acting on the slipper pair in the contribution to the pressing force gradually increases. When the rotational speed increases to 5000 r/min, the supporting force cannot effectively compensate for the external pressing force, resulting in the rupture of the hydrostatic oil film of the slipper pair. The slipper and the swash plate change from the fluid lubrication state to the boundary lubrication state or the direct contact state. Moreover, the pv value of the material of the slipper pair is in an over-limit state under the high rotational speed operating condition, which ultimately leads to wear failure.

The disc spring hydraulic mechanism is a key equipment in the power system, and its performance directly impacts the reliability of the system. Dynamic characteristic analysis of its key components aims to enhance operational stability. The mechanism's structural composition and operational principles are analysed firstly. Subsequently, Fluent-based simulations investigate the pressure variation characteristics in both rodless and rod cavities of the working cylinder piston. These simulations reveal the intrinsic correlation between piston velocity and pressure fluctuations. Further research focuses on gas pressure dynamics in the arc-extinguishing chamber during circuit-breaking operations, employing pressure cloud diagrams to analyse the spatial-temporal pressure distribution patterns in both the disc spring hydraulic mechanism and the arc-extinguishing chamber. Experimental validation confirms the accuracy of this dynamic analyses, establishes a theoretical foundation for optimizing mechanism design and improving operational stability.

There are problems of unstable control accuracy and imperfect matching of various types of equipment in current proportional control valve drivers, which cannot meet the flexibility, rapidly and localization requirements of modern electro-hydraulic control systems a digital-analog hybrid proportional control valve driver based on the GD32F450ZKT6 control chip is developed. The designed driver integrates a main control module circuit, power amplification circuit, ADC sampling circuit, and CAN/USB communication circuits, thereby enabling the realization of multiple command signal inputs, host computer parameter configuration, and output precision control functions. A test platform is further established to conduct the performance of the hybrid proportional control valve driver. The results show that the developed driver achieves an output accuracy of less than 2% under diverse signal command inputs, incorporates comprehensive control parameter configuration capabilities, and effectively satisfies the electro-hydraulic control requirements across multiple operational scenarios.

Sticking mayoccur in drilling different coal rocks for a coal mine anti-impact drilling robot, and it may lead to drilling failure, which seriously affects the safety of drilling pressure relief operations, the quality and efficiency ofanti-impact pressure relief hole formation. To this end, an anti-sticking electro-hydraulic control strategy is proposed for coal rock drilling system. The mechanism of sticking is analyzed based on the variation of drilling parameters during drilling, and the drilling state is judged by combining support vector machines. The electro-hydraulic control strategy of anti-sticking based on sliding mode variable structure is designed. A joint simulation model of AMESim and MATLAB/Simulink is established, and the control characteristics of the anti-sticking is analyzed. The designed anti-sticking electro-hydraulic control experimental platform is executed for verification. The results indicate that the proposed anti-sticking electro-hydraulic control strategy can effectively identify the drilling status and reduce the risk of sticking, and can improve drilling efficiency and safety under different coal rock conditions.

Shear thickening fluid is a kind of intelligent material, and when applying the shear thickening fluid to the damper, we obtain the shear thickening fluid damper. Based on the reason that shear thickening fluid damper will be subjected to huge resistance due to the existence of velocity gradient when the fluid flows through small pores or gaps, the shear thickening fluid damper plays a key role in energy absorption and shock absorption. Through the way of Fluent simulation, the shear thickening fluid which is made of 20% mass fraction of nano-silica-polyethylene glycol solution is used as the working medium of the shear thickening fluid damper, and the flow of the shear thickening fluid in the damping holes is used to simulate the working process of the damper, and then draw the force-displacement hysteresis curves at different frequencies. The energy produced by the resistance force during the working process of the shear thickening fluid damper is calculated according to the results of the hysteresis curve to analyze the energy absorption effect. From the results, it is known that under the condition of the low-frequency working environment (f≤2 Hz), the force-displacement curve shows a good characteristic of symmetry, and the energy consumed in the retraction process of the damper is almost equal to that in the process of extension. But with the increase of frequency (f>2 Hz), the symmetric characteristic of the force-displacement curve becomes worse, and the energy consumed in the retraction process of the damper and the extension process are quite different.

Multi-degree-of-freedom hydraulic manipulators prominently exhibit strong joint coupling characteristics and large dynamic model errors, which leads to degraded control performance. To achieve high-precision pose control, a dual robust integral of sign error controller with prescribed performance function is proposed. Based on the prescribedperformance function, the transformed error signal is obtained, simultaneously limiting the rate and range of error convergence. Combined with the backstepping method, a dual robust integral of sign error controller is designed to suppress both matched and unmatched uncertainties, enhancing the robustness of system. The semi-global stability of the system and the boundedness of all signals are proved by Lyapunov stability theory. The results show that the proposed control strategy significantly improves the joint tracking accuracy and error convergence rate of multi-degree-of-freedom hydraulic manipulators, fully verifying the effectiveness of this control strategy.

To address the challenge in the domestic substitution of high-pressure hydraulic pumps, this paper proposes a tandem dual-output hydraulic pump power source. By connecting a secondary pump in series to the outlet of the primary pump, the system achieves stage-by-stage pressurization, fulfilling high-pressure requirements without modifying low-performance pumps. The tandem structure significantly reduces the pressure difference across single pumps, extends their service life, and isolates load impacts through accumulators. SimulationX-based analyses on flow pulsation and energy efficiency performance reveal the following results: Under conditions of 20 MPa and 1500 r/min, the flow pulsation rate is reduced by 37% compared to single-stage gear pumps. The system energy efficiency for driving high and low-pressure load hydraulic cylinders reaches 61% when adopting the proposed tandem power source, substantial improvement over the 36% efficiency of a single-stage variable displacement axial piston pump. These findings provide innovative insights for the design of power sources in complex high-pressure hydraulic systems.

By designing different anti-friction lubricating structures and comparing the oil film characteristics, the influence of different anti-friction lubricating structures on the servo hydraulic cylinder to overcome the radial load and reduce the friction is studied, the best shape structure of anti-friction lubricating structure is obtained, and tests are verified. Based on the rectangular structure of anti-friction lubricating, I-shaped structure and trapezoidal structure are proposed. The pressure distribution and bearing capacity characteristic curves of different anti-friction lubricating structures are obtained by theoretical analysis and flow field simulation. The anti-friction lubricating structure of trapezoidal structure can provide more bearing capacity, and the temperature rise of oil film is smaller. The anti-friction lubricating structure can effectively overcome the radial load on the piston rod and reduce the friction of the servo hydraulic cylinder. The results show that the oil film characteristics of different anti-friction lubricating structures are different, which can effectively overcome the partial load, greatly reduce the friction of the servo hydraulic cylinder, and improve the control precision and service life of the servo hydraulic cylinder.

Due to strong nonlinearity, complex multivariable coupling and difficulty in real-time state observation, pneumatic soft robotic arms pose significant challenges for dynamic control. To address these issues, this study proposes a real-time motion control method integrating visual localization and neural network modeling. A vision system is constructed using YOLOv8 object detection and semi-global stereo matching to generate sequential datasets. A long short-term memory network is then employed to model the dynamic relationship between chamber pressure and end-effector position. The results show that compared to neural networks trained on discrete data, the long short-term memory model significantly reduces the mean absolute error in three-channel pressure prediction from approximately 1.65 kPa to 0.44 kPa. Further experiments demonstrate that the proposed method achieves average mean absolute error of 1.503, 1.506, 2.825 mm along the three spatial axes, validating the effectiveness of the vision-based sequential neural network control strategy in dynamic trajectory tracking of soft robotic arms.

Aiming at the challenges of poor road conditions, complex environments, this study proposes an active vibration reduction scheme using a tractor electro-hydraulic suspension based on digital valves in order to improve stability and comfort during tractor transportation. Highly responsive digital hydraulic valves are used to adjust the speed and displacement of the implement hitch cylinder in real time to counteract vibration. Firstly, a dynamics model of tractor vibration system with suspended implements is derived. A sliding mode controller is designed, and a simulation model is developed to investigate the active vibration reduction performance under random road, sinusoidal road, and pulse road conditions. The results demonstrate that effective vibration suppression is achieved under all three road conditions. Specifically, under a 20 km/h random road excitation, the peak vertical acceleration of the tractor can be reduced by the active vibration reduction system of electro-hydraulic suspension from 2.13 m/s² to 1.01 m/s², and the root mean square value decreases from 0.84 m/s² to 0.28 m/s², achieving a 63% reduction compared to passive vibration reduction systems, which results in excellent vibration reduction.

It is crucial to select appropriate control parameters to improve the motion control accuracy of the pneumatic sliding table. However, the traditional trial-and-error method is inefficient and heavily reliant on experience of parameter adjusters. Therefor, a novel improved particle swarm optimization algorithm is presented. This algorithm applies an improved Gaussian-sine chaotic mapping technique to generate initial particles so as to enrich the diversity of the population. It introduces sine disturbance and Lévy flight strategy to help particles escape local optima. Additionally, it integrates the sine-cosine algorithm and an improved slime mold algorithm to improve search accuracy. The experimental results from linear active disturbance rejection motion control tests on the pneumatic sliding table show that the proposed novel particle swarm optimization algorithm can effectively improve control accuracy. Compared with the trial and error method,it reduces the maximum steady-state error by 15.9% and 23.4% respectively when tracking sinusoidal trajectories with an amplitude of 150 mm and frequencies of 0.25 Hz and 0.5 Hz. And it reduces the maximum steady-state error by 13.5% when tracking multi frequency curves.

To address the issue of insufficient adjustability of low-frequency dynamic characteristics in heavy-duty special vehicle mount systems, this study proposes a magnetorheological fluid mount with controllable multi-inertial channel combined squeezing mode. A multi-channel magnetorheological fluid damper is developed, and experimental methods are employed to validate the switching effect of controllable flow channels. An aggregate parameter model for the magnetorheological fluid mount with controllable multi-inertial channel combined squeezing mode and a model of magnetorheological fluid mount system for 1/4 heavy-duty special vehicle are established. Finally, dynamic characteristics and vibration isolation performance are investigated based on these models. The results demonstrate that by the application of large current on different inertial channels, the peaks and peak frequencies of dynamic stiffness and hysteresis angle in the magnetorheological fluid mount become adjustable within 0~50 Hz. Additionally, under squeezing mode operation, the mount exhibits high-stiffness and high-damping characteristics at low frequencies.

A new configuration of plate pilot pressure control for two-stage flow distribution hydrostatic-balanced high-pressure radial piston motor is proposed to address the problems of the large lateral forces on the piston pair lead to large transmission shocks at start/stop moments, serious leakage of the flow distribution and piston gap and low volumetric efficiency of traditional radial piston motors under high-pressure working conditions. This new model adopts composite pistons assemblies and pilot pressure control two-stage flow distribution method to achieve high-pressure power oil circuit sealing and high-efficiency flow distribution. In addition, the hydraulic floating support structure is adopted for the pilot stage flow distributor to compensate for mechanical wear and improve the reliability of long-time continuous operation. Based on AMESim, the dynamic simulation model of the whole motor is established. The thesis analyzes the correspondence between motion of single piston and its distribution valve, the influence of diameter of damping hole of distribution valve, the working pressure and main stage supply flow rate on the volumetric efficiency of the motor, and also analyzes the output characteristics of the motor with different transmission structures. The simulation results show that the motor has a volumetric efficiency of 89.74% at high pressure of 35 MPa. The pulsation rate of the output speed is reduced by 60% compared with that of the crankshaft linkage motor. It also has good low-speed stability and wide load adaptability. The results show a theoretical basis for the design and optimization of the high-pressure hydrostatic balance radial piston motor prototype is provided.

Designing airfoils with biomimetic leading-edge structures offers an effective approach to concurrently improve aerodynamic and noise reduction performance. Five biomimetic airfoils with wavy leading-edge characterized by different combinations of amplitude and wavelength are designed using the NACA0012 airfoil as a baseline. Numerical simulations employing the SST k-ω and large eddy simulation methods are performed to analyze their aerodynamic performance and flow noise. The results indicate that increasing the wavelength significantly improves aerodynamic performance, with the lift-drag ratio enhanced by up to 21.8%. Increasing the amplitude strengthens flow control at the leading edge, resulting in a more uniform pressure distribution and delayed flow separation. The biomimetic structure reduces the angle of attack corresponding to the maximum lift-drag ratio and improves aerodynamic performance at high angles of attack. The biomimetic airfoils demonstrate notable noise reduction in the mid-to-high frequency range. Under small angles of attack, both tonal and broadband noises are suppressed. A reduction in sound pressure level is observed across all studied angles, peaking at 14 dB at an angle of attack of 3°.

Due to the inherent structure of hydraulic transformer, its piston pairs are more complex during operation. In order to prevent the problems such as jamming or low volumetric efficiency during the operation of hydraulic transformers, the lubrication characteristics of the piston pair for hydraulic transformer are studied. The transformer ratio of hydraulic transformer and the Reynolds equation of piston pair are derived and solved by using ANSYS. The results show that the oil film pressure, leakage and axial viscous friction of piston pair are complex due to the influence of hydraulic transformer structure, which are related to the piston movement speed, piston cavity pressure and rotation speed. Through the orthogonal test, it is found that the main factors affecting the lubrication characteristics of piston pair are fit clearance and A-port pressure.

Addressing the issue of the unstable output and low accuracy issues of single-rod hydraulic cylinders under heavy load, high stiffness, and dynamic disturbances, a nonlinear model of the hydraulic system is established based on the analysis of force-bearing process and structural characteristics. Then an adaptive control method based on an asymmetric barrier Lyapunov function is proposed to performance steady tracking under output force constraints. The controller integrates adaptive parameter, extended state observer, and dynamic surface control and handles the system's parameter uncertainties, unknown states estimation and time-varying disturbances, and complexity explosion caused by high-order derivatives. The output force boundaries are constrained by the constructed asymmetric barrier Lyapunov function. Lyapunov-based analysis proves the system's asymptotic stability. Co-simulation verifys control effectiveness. The results show that the proposed method can accurately estimate and compensate for uncertainties, ensure the output remains within safe boundaries during loading while achieving high-precision actuator's position tracking.

We design a purely soft-structured gripper and analyze the bending performance of its finger section. The gripper features a series of gas-driven elliptical cavities. A stepped cavity structure incorporates three parallel air channels for the fingertip, middle finger segment and finger root, respectively. The palm adopts an arc-triangle shape. The gripper is made of hyperelastic material Ecoflex 00-30 silicone rubber and polydimethylsiloxane, and its model uses the Yeoh constitutive model derived from uniaxial tensile theory. Building on this, we develop models for a single airbag, a single cavity group's bending and the bending deformation prediction of the entire multi-channel fully flexible gripper. Inputting the finger's structural parameters into the mathematical model yields the geometric relationship of its bending curve. The comparison of these analytical results with simulation data verifies the model's accuracy and practicality. Finally, analyzing the finger's bending performance allows us to determine optimal gripper performance parameters. Key factors include cavity structure type/number, finger width, cavity gap length and the bottom strain-limiting layer. This provides valuable research data and a reference for soft actuator development.

To address the dynamic and efficient supply-demand matching between fully-mechanized-mining-equipment and fluid supply systems in fully mechanized coal mining faces, this study proposes a digital flow control technology to achieve on-demand fluid supply in pump stations. Firstly, the working principle of digital flow control technology is elaborated, and an actuator work strategy compatible with the flow distribution characteristics of a 5-plunger pump is formulated. Secondly, digital flow control schemes are systematically summarized. Finally, the optimal control scheme is selected, and its reliability is verified through simulation. The results indicate that the 5-plunger emulsion pump has 7 possible digital flow control schemes, with the number of engaged actuators exhibiting a negative correlation with flow pulsation rates. Depending on the scheme, the control intervals are either [0, π] or [0, 3π/5), enabling a flow adjustment range of 38%~100%. This approach not only meets on-demand fluid supply requirements but also minimizes flow pulsation, providing valuable insights for intelligent constant-pressure liquid supply technologies in fully-mechanized-mining-equipment.

By analyzing several methods for characterizing filtration rating,the importance of filtration rating in evaluating the performance of hydraulic filters is pointed out. Based on the commonly used filtration rating of hydraulic filters, several nominal opening corresponding to them are selected for experimental research on fully wrapped dense woven wire cloth with slanting weave. The research results indicate that the dense woven wire cloth can be characterized by the mean flow pore size and corresponding particle size under filtering ratio β_x(c) 100. Through fitting analysis, it is confirmed that there is a good correlation among the nominal opening, the mean flow pore size and corresponding particle size under filtering ratio β_x(c) 100 of the dense woven wire cloth. Using fitting equations to directly derive the mean flow pore size or corresponding particle size of the dense woven wire cloth through the nominal opening. The research results can provide useful references for design and selection of metal wire weaving dense woven wire cloth hydraulic filters.

Airtightness testing is a crucial technical measure to ensure the specific pressure chambers sealing performance. The direct pressure testing method is widely adopted in the manufacturing of such chambers due to its simple principle and convenient operation. However, its energy consumption issues have not received sufficient attention. To address energy waste caused by direct emission of compressed air after single-use in conventional direct pressure testing, a detection gas recovery and reuse method based on recycle air tanks is proposed, aiming to design an energy-saving direct pressure testing system that integrates high-precision detection and one-click start-stop functionality. A human-machine interface is developed via programming software to achieve solenoid valve switching control and real-time pressure monitoring during testing. The results demonstrate that the gas recovery and reuse scheme significantly reduces compressed air consumption, achieving a 16.2% reduction in energy consumption per test, which provides theoretical foundations and engineering references for energy optimization in direct pressure airtightness testing.

Dynamic seals in hydraulic slide valves play a crucial role in reducing oil leakage. However, their sealing performance is significantly influenced by environmental temperature, medium temperature and oil pressure, which alter the seal clearance during operation. A finite element analysis model is developed to analyze the combined sealing structures commonly used in slide valves. The model is used to evaluate the effects of varying environmental and medium temperatures, as well as pressure conditions on the clearance and friction behavior of dynamic seals. Based on the Stribeck curve, a mathematical expression describing the relationship between seal clearance and the friction coefficient is introduced. Experimental validation confirmed the accuracy of the theoretical model. The results indicate that the gap between the fluoroplastic sealing ring and the valve sleeve decreases with increasing temperature, accompanied by a corresponding change in the dynamic friction coefficient. Furthermore, both the theoretical analysis and experimental data reveal that the friction force of the dynamic clearance seal increases with temperature.

The aircraft landing rollout scenario is one of the critical scenes in the overall flight mission process, involving disciplines such as mechanics, fluid dynamics and aerodynamics. Using traditional system modeling approaches for this scenario is complex and cumbersome. Utilizing the Modelica unified modeling language, this study focuses on constructing component-level and system-level models for a specific aircraft's landing gear and its landing rollout scenario. Key parameters at the component-level and the braking performance of the aircraft system during the landing rollout are simulated and analyzed. A general virtual experimentation based on this model can verify the correctness and rationality of the design parameters.

Aiming at the nonlinear control of multiple hydraulic joint system of hydraulic quadruped robot, an interactive force control strategy for floating base operation by force control is proposed. The control strategy transforms the basic motion, robot end motion, leg motion, interaction force control, joint constraint and friction cone constraint into a quadratic programming optimization problem, and the task priority is adjusted by the weight matrix. The robot task is decomposed under the position constraint to solve the conflict between the interactive force control and the optimal control based on the dynamic model, to realize the coordinated motion and force control of the robot end. Finally, the effectiveness of the proposed control strategy is verified by simulation and experiment, which shows that the hydraulic quadruped robot can perform large load operation during interactive operation and can control the appropriate contact force.