On March 28, 2026,Professer YANG Huayong, member of the Chinese Academy of Engineering, dean of the Faculty of Engineering of Zhejiang University, director of the State Key Laboratory of Fluid Power and Mechatronic Systems, and president of the Institute of Advanced Equipment of Zhejiang University, delivered a report entitled “Exploration on Artificial Intelligence Empowering the Intelligentization of Construction Machinery” at the 14th Conference on Fluid Power Transmission and Control held in Wuhan, Hubei Province. In his presentation, YANG addressed the practical requirements for construction machinery to achieve minimal staffing, unmanned operation, and high reliability. He focused on three key technologies: an intelligent digital foundation, vertical large models integrating general and specialized capabilities, and edge intelligent terminals with high computing power. Drawing on research progress in remote operation and coordinated excavation, loading, and transportation in unmanned mines; intelligent shield/TBM tunneling in long tunnels; and intelligent operation and maintenance of large equipment, he elaborated in depth how artificial intelligence extends from computing centers to engineering sites and from supporting decision-making to autonomous decision-making. His insights offer new ideas for the intelligent upgrading of fluid power transmission and control. The following text is compiled from the content and presentation of YANG Huayong’s report.

To address the challenge of coordinating local friction reduction with cylinder block tilt control in the valve plate pair of ultra-high-pressure axial piston pumps, a micro-wedge structure is proposed on the auxiliary supporting land of the valve plate. A quasi-thermo-elasto-hydrodynamic mixed lubrication model is developed, considering micro-wedge geometry, cylinder block attitude, oil film pressure, end-face elastic deformation, viscosity-temperature and pressure-viscosity effects, and Greenwood-Williamson asperity contact. A 63 MPa case is used to analyze the effects of micro-wedge depth on oil film thickness, contact load, friction power loss, pressure center, and cylinder block tilt angle. Results show that the micro-wedge generates a locally convergent oil film and induces additional hydrodynamic pressure. This increases the fluid load-bearing share and reduces both the contact load ratio and the real contact area ratio, thereby improving the mixed lubrication state. However, the local hydrodynamic pressure also redistributes the end-face pressure, shifts the pressure center, and changes the supporting moment. As a result, the cylinder block tilt angle increases with micro-wedge depth. This reveals a trade-off between the benefit of friction reduction and increased cylinder block tilt.

The high-speed and high-pressure performance limitations of axial piston pumps constrain the electrification process of construction machinery. The main reason is that the dynamic characteristics of the valve plate pair under severe operating conditions remain unclear, and forward design lacks theoretical support. We establish a dynamic model of the cylinder block and a numerical model of the dynamic oil film. The models are used to investigate the dynamic characteristics of the spherical valve plate pair oil film under high-pressure and heavy-load conditions. The analysis focuses on the effects of rotational speed and load pressure on oil film pressure distribution, thickness distribution, and cylinder block overturning degree. The results indicate that under a load pressure of 40 MPa, the pressure on the valve plate pair increases significantly with increasing rotational speed. At 4000 r/min, the pressure overshoot reaches 68%. When the rotational speed is constant at 4000 r/min, increasing load pressure decreases the oil film thickness difference and reduces the cylinder block overturning degree, thereby improving anti-overturning characteristics. Under a constant load pressure of 40 MPa, increasing rotational speed enlarges the oil film thickness difference and increases the cylinder block overturning degree. Therefore, appropriately reducing rotational speed helps enhance the anti-overturning characteristics of the cylinder block.

We present a novel two-dimensional cartridge-type bidirectional proportional throttle valve for suspension systems, which innovatively integrates two-dimensional, logic, and main valve structures. By utilizing circumferential spool rotation for precise throttling area control and axial displacement for symmetric bidirectional flow guidance, the design overcomes the bulkiness and high nonlinear resistance associated with traditional check-valve-dependent configurations. A coupled mathematical model of the spool's rotary and sliding motions is developed, and AMESim simulations are conducted to analyze the effects of key structural parameters on static and dynamic performance. The results demonstrate that the valve achieves a rated flow of 80 L/min at 21 MPa, with a hysteresis of 0.5%, a linearity of 3%, and a step response time within 15 ms. The valve provides continuously controllable damping across a wide range with superior symmetry and stability, proving its efficacy for semi-active suspension systems in heavy-duty vehicles.

To investigate contamination-induced sticking in hydraulic servo spool valve, modeled visualization experiments and Fluent-based Euler-Euler solid-liquid two-phase flow simulations are used to study particle trajectories and distribution characteristics in grooves. Results show that particles move periodically along arc-line trajectories in the clearance, and the lateral offset gradually decreases. Along the gap horizontal direction, particle distribution exhibits a multi-peak attenuation pattern. Along the groove depth direction, it forms a five-region structure: the suspension region, upper streamline region, main-flow region, lower streamline region, and groove-bottom deposition region. Owing to the first-groove effect, the peak particle volume fraction reaches 0.105. Decreasing groove spacing increases both the peak particle volume fraction and groove-bottom deposition. Under the double-groove condition, the peak value in the first groove increases by about 18% compared with that under the single-groove condition. When the groove position is shifted downstream by 0.4 mm, the peak value in the first groove increases from 0.052 to 0.064. These results provide a theoretical basis for the high-reliability design of hydraulic servo valve.

Centrifugal water mist nozzles are prone to pollution and blockage under impurity conditions. To investigate this problem, four centrifugal nozzles with different inlet structures are designed based on Abramovich's maximum flow principle. The flow rate is kept consistent at a pressure of 0.5 MPa. The internal and external flow fields, atomization characteristics, and anti-pollution performance are numerically simulated using Fluent. The atomization characteristics are evaluated using the volume of fluid method, and the anti-pollution performance is assessed indirectly by the particle phase. The results show that, under the same inlet type, a larger inlet diameter leads to better anti-pollution performance. The flow field in the cylindrical inlet nozzle is more stable, and its anti-pollution performance is superior to that of the thin-walled conical inlet nozzle. The simulation results are validated by pressure-flow and anti-pollution experiments. The experimental results agree well with the numerical results, and the deviation between the measured and theoretical flow rates is within the allowable range.

To improve the reduced flow measurement accuracy caused by uneven gas velocity distribution under high-flow conditions, we propose a bypass-type ultrasonic gas flow sensor. A CFD model is established in COMSOL to systematically investigate the flow division characteristics of four throttling-element structures with bypass inlet diameters ranging from 2 to 6 mm. The results show that all structures maintain a stable bypass flow ratio in the high-flow range of 50~120 L/min, but different degrees of deviation appear in the low-flow range of 5~50 L/min. The blade-type element exhibits a lower flow division ratio, and its optimal inlet size minimises the maximum relative error to 3.25%. This feature helps extend the upper limit of stable flow measurement and simplify subsequent calibration. The orifice-type element shows better linearity in the high-flow range, with a minimum standard deviation of 0.012%, indicating greater potential for high-precision and robust measurement. Experiments are conducted on the selected structure, and the results agree well with the simulation, which validates the effectiveness of the CFD model. This study clarifies the flow division characteristics of different structures and provides preferred design solutions and theoretical support for different application scenarios.

As axial piston pumps in construction machinery evolve toward operation over a wide speed range, lubrication issues with the slipper pair, particularly at low speeds, have become increasingly prominent. Under low-speed conditions, the film thickness of the slipper pair is on the same order of magnitude as the surface roughness; consequently, the influence of surface roughness on lubrication performance cannot be neglected. Based on this premise, a lubrication equation for the slipper pair that accounts for the impact of surface roughness is proposed. Combined with the motion equation and the force and moment balance equations of the slipper pair, a mathematical model for slipper pair lubrication analysis is developed. A systematic analysis is conducted to investigate the influence of key parameters, including root mean square roughness, shaft rotation speeds, spring compression forces, and hydraulic oil dynamic viscosity, on the lubrication performance of the slipper pair. The results show that the minimum film thickness of the slipper pair increases with increasing root mean square roughness, shaft rotation speed, and hydraulic oil dynamic viscosity. The minimum film thickness decreases with increasing spring compression force. This study provides a theoretical foundation for the analysis and optimization of slipper pair lubrication performance in axial piston pumps operating over a wide speed range.

Semiconductor wet processes require chemical delivery systems with low pulsation, high cleanliness, and a compact footprint. Pneumatic bellows pumps are well suited for this task because of their low energy consumption and strong self-priming capability. However, output pulsation still undermines supply stability, and existing pneumatic bellows dampers have difficulty achieving both lower pulsation and compact design. To address this issue, we propose a pneumatic-feedback pneumatic bellows damper and develop an integrated liquid supply system. A multi-domain coupled dynamic model is established to reveal the motion sequence and pulsation attenuation mechanism, and to determine the main structural parameters. Based on AMESim co-simulation, sensitivity analysis is performed, and key parameters are optimized using particle swarm optimization with output pulsation as the objective. A prototype is then developed and validated against a conventional system. The results show that the optimized design reduces the output pressure pulsation amplitude by 79.67%, decreases the peak-to-valley flow variation of the integrated system by 75%, and reduces the system volume by 74%. These results demonstrate a coordinated improvement in pulsation suppression and compactness.

To overcome the limitations of conventional pipe robots in load capacity and locomotion speed, a water hydraulic artificial muscle-driven bionic earthworm-like pipe robot is proposed. Benefiting from the properties of water hydraulic artificial muscles, the robot possesses bend-passing ability and good adaptability to pipe environments. Based on the peristaltic locomotion mechanism of earthworms, a highly flexible and adaptive in-pipe mobile platform is developed, and the corresponding robot model is established. To enhance locomotion performance, the structural parameters are designed and an efficient gait is planned. An experimental platform is further constructed to carry out in-pipe performance tests. Experimental results indicate that the robot achieves a locomotion speed of 8.32 mm/s.

High-fidelity modeling and fail-safe assessment of hydraulic pitch actuators become increasingly important with the development of large offshore wind turbines. Simplified models often fail to represent the key dynamic characteristics of valve-controlled hydraulic pitch systems because of valve-port nonlinearities, such as saturation, dead zone, and hysteresis, as well as spool dynamics. An 8 MW valve-controlled hydraulic pitch system is investigated, and a component-level nonlinear model is established in AMESim. A PI+Gate strategy is introduced into the position closed loop to suppress ineffective integral accumulation in the small-error region. According to IEC 61400-1 DLC2.1, the equivalent pitch-axis torque is converted into the cylinder-end load through the equivalent mechanical lever arm and then applied by a lookup table. The simulation results show that PI+Gate significantly reduces overshoot compared with conventional PI control. The improvement in steady-state error and overshoot is most evident under the 25° condition. Under the 90° condition, the holding accuracy at the target position also improves, although the settling time under small and medium angle conditions increases slightly. Under the specified boundary conditions, the accumulator completes emergency feathering from 0° to 90° after power loss and retains a residual pressure of about 9 MPa.

The hydraulic flow demand of flight control surfaces during typical flight profiles is particularly critical for determining the rated operational flow of the hydraulic system, defining key performance indicators of hydraulic system onboard equipment, and designing pipeline diameters. However, the accuracy of hydraulic flow calculations during the design phase is currently insufficient, leading to significant over-design issues. During the testing phase, the iron bird test rig can measure the hydraulic flow of control surfaces in simulated flights, but discrepancies remain compared to actual flight conditions. In the flight test phase, installing contact-based flow sensors is challenging, and such sensors can impact the system's inherent characteristics. Alternatively, non-contact ultrasonic flow sensors exhibit measurement inaccuracies. To address these issues, we propose a calibration method for the hydraulic flow of control surfaces based on models and flight data. Focusing on a specific hydraulic system and its flight control surfaces, a power calculation model is established and refined using data from the iron bird test rig. The maximum error between simulated flow results and experimental data does not exceed 2 L/min. Using flight data as model inputs, the hydraulic flow demand of flight control surfaces during typical flight profiles is calculated, enabling the calibration of hydraulic system power design and supporting optimized hydraulic system design.

Industrial pneumatic systems are widely used in automation but have low energy efficiency. The uniform pressure air supply mode causes excessive air supply and wastes a large amount of compressed air. An energy-saving method based on nonlinear optimization for distributed pressure supply systematically reduces pressure energy waste in multi-actuator pneumatic systems. First, a mathematical model of the pneumatic system quantifies its energy consumption. Next, the cylinder-valve matching problem forms a combinatorial optimization model that minimizes total air consumption. The tabu search algorithm solves this model efficiently and outputs the optimal grouping and supply pressure settings. Finally, an experimental platform with 17 heterogeneous cylinders validates the method. Results show that the optimized distributed pressure supply strategy significantly reduces system energy consumption: single-cycle air consumption decreases from 19.04 L (uniform supply) to 9.07 L, achieving a 52.34% energy saving rate. These results confirm the effectiveness of intelligent optimization in pneumatic energy-saving design and provide a feasible solution for industrial retrofits.

Velocity disturbances and chatter occur during the point-to-point constant-velocity compaction of polymer-bonded explosive granules under a fixed-stroke condition. To address this problem, we propose a motion control method for precision compaction forming of granular materials based on strong nonlinear load disturbance compensation. First, the load pressure is redefined using an equivalent pressure-bearing area weighted-average method, and a mathematical model of the electrohydraulic position servo system of the precision compaction hydraulic press is established. Then, a nonlinear load observation compensator based on a cancellation mechanism is developed, enabling the system to be transformed into a quasi-decoupled linear system. Finally, experimental validation is carried out on the developed precision compaction hydraulic press. The results show that compared with PID control, the standard deviations of the velocity disturbances of the lower and upper punches are reduced from 0.0555 mm/s and 0.0550 mm/s to 0.0416 mm/s and 0.0442 mm/s, respectively, corresponding to reductions of 25.1% and 19.6%. In addition, the proposed nonlinear load observation compensator improves the compact density and density uniformity, reducing the overall porosity of the compact from 3.472% to 1.980% and the standard deviation of the layer-wise axial porosity from 0.511% to 0.452%.