Search Results (419)

Analysis of the rock mining process using an experimental cutterhead employing milling and chipping processes is the subject of this article. Based on a bibliographic review of the energy consumption of rock mining and wear and tear of various mining tools, a stand test programme for the rock mining process using the experimental cutterhead was developed. Based on the following measured parameters—hydraulic motor supply pressure and displacement, hydraulic motor shaft speed, cutterhead web depth, cutterhead tilt angle relative to the mining direction, feed pressure in the advance cylinder, duration of each mining stages, cutterhead travel distance, angle of the cutterhead chipping part, and known physical and strength parameters of the mined rock—the following parameters were determined: cutterhead advance speed, cutterhead advancing force, cutterhead driving motor power, advancing cylinder power, and the parameters of energy consumption in the mining process, including specific energy of mining, specific energy of feed, and specific energy of cutting. The effects of cutterhead advance speed and tilt angle on the specific mining energy and the grain size distribution of the mined rock were determined. Analysis of test results enabled the development of the procedure for selecting the most favourable parameters of rock mining technology when using an experimental cutterhead. Full article

To address the technical challenge where traditional high-pressure, large-flow emulsion pump stations cannot adapt to the drastic flow rate changes in hydraulic supports due to the fixed displacement of their quantitative pumps—leading to frequent system unloading, severe impacts, and damage—this study proposes an intelligent flow control method based on the digital flow distribution principle for actively perceiving and matching support demands. Building on this method, a compact, electro-hydraulically separated prototype with stepless flow regulation was developed. The system integrates high-speed switching solenoid valves, a piston push rod, a plunger pump, sensors, and a controller. By monitoring piston position in real time, the controller employs an optimized combined regulation strategy that integrates adjustable duty cycles across single, dual, and multiple cycles. This dynamically adjusts the switching timing of the pilot solenoid valve, thereby precisely controlling the closure of the inlet valve. As a result, part of the fluid can return to the suction line during the compression phase, fundamentally achieving accurate and smooth matching between the pump output flow and support demand, while significantly reducing system fluctuations and impacts. This research adopts a combined approach of co-simulation and experimental validation to deeply investigate the dynamic coupling relationship between the piston’s extreme position and delayed valve closure. It further establishes a comprehensive dynamic coupling model covering the response of the pilot valve, actuator motion, and backflow control characteristics. By analyzing key parameters such as reset spring stiffness, piston cylinder diameter, and actuator load, the system reliability is optimized. Evaluation of the backflow strategy and delay phase verifies the effectiveness of the multi-mode composite regulation strategy based on digital displacement pump technology, which extends the effective flow range of the pump to 20–100% of its rated flow. Experimental results show that the system achieves a flow regulation range of 83% under load and 57% without load, with energy efficiency improved by 15–20% due to a significant reduction in overflow losses. Compared with traditional unloading methods, this approach demonstrates markedly higher control precision and stability, with substantial reductions in both flow root mean square error (53.4 L/min vs. 357.2 L/min) and fluctuation amplitude (±3.5 L/min vs. ±12.8 L/min). The system can intelligently respond to support conditions, providing high pressure with small flow during the lowering stage and low pressure with large flow during the lifting stage, effectively achieving on-demand and precise supply of dynamic flow and pressure. The proposed “demand feedforward–flow coordination” control architecture, the innovative electro-hydraulically separated structure, and the multi-cycle optimized regulation strategy collectively provide a practical and feasible solution for upgrading the fluid supply system in fully mechanized mining faces toward fast response, high energy efficiency, and intelligent operation. Full article

Hydraulic thrust cylinders in hard-rock tunnel boring machines (TBMs) often exhibit slow response and sluggish acceleration during start-up, which degrades early-stage tracking performance and limits overall operational accuracy. Most existing studies primarily enhance start-up behavior through advanced control algorithms, yet the achievable improvement is ultimately constrained by the system’s flow–pressure capacity. Meanwhile, reported system-level optimization approaches are either difficult to implement under practical TBM operating conditions or fail to consistently deliver high-accuracy tracking. To address these limitations, this paper proposes a “dual-pump–single-cylinder” control framework for the TBM thrust system, where a large-displacement pump serves as the main supply and a parallel small-displacement pump provides auxiliary flow compensation to mitigate the start-up flow deficit. Building on this architecture, an adaptive compensation algorithm is developed for the auxiliary pump, with its output updated online according to the system’s dynamic states, including displacement error and velocity-related error components. Comparative simulations and test-bench experiments show that, compared with a single-pump scheme, the proposed method notably accelerates cylinder start-up while effectively suppressing overshoot and oscillations, thereby improving both transient smoothness and tracking accuracy. This study provides a feasible and engineering-oriented solution for achieving “rapid and smooth start-up” of TBM hydraulic cylinders. Full article

Tunnel boring machine (TBM) hydraulic cylinders operate under pronounced start–stop shocks and load uncertainties, making it difficult to simultaneously achieve smooth start-up and high-precision tracking. This paper proposes a two-phase switching adaptive sliding mode control (ASMC) strategy for TBM hydraulic actuation. Phase I targets a soft start by introducing smooth gating and a ramped start-up mechanism into the sliding surface and equivalent control, thereby suppressing pressure spikes and displacement overshoot induced by oil compressibility and load transients. Phase II targets precise tracking, combining adaptive laws with a forgetting factor design to maintain robustness while reducing chattering and steady-state error. We construct a state-space model that incorporates oil compressibility, internal/external leakage, and pump/valve dynamics, and provide a Lyapunov-based stability analysis proving bounded stability and error convergence under external disturbances. Comparative simulations under representative TBM conditions show that, relative to conventional PID Controller and single ASMC Controller, the proposed method markedly reduces start-up pressure/velocity peaks, overshoot, and settling time, while preserving tracking accuracy and robustness over wide load variations. The results indicate that the strategy can achieve the unity of smooth start and high-precision trajectory of TBM hydraulic cylinder without additional sensing configuration, offering a practical path for high-performance control of TBM hydraulic actuators in complex operating environments. Full article

Due to a number of advantages, such as the high power-to-weight ratio of the system, the possibility of easy control and the freedom of arrangement of the system components on the machine, hydrostatic drive is one of the most popular methods of machine drive. The actuators in such a system are hydraulic cylinders that convert fluid pressure energy into mechanical energy for reciprocating motion. One disadvantage of conventional actuators is their weight, so research is being conducted to make them as light as possible. Directions for this research include the use of modern engineering materials such as composites and plastics. This paper presents the possibility of using new lightweight yet strong materials for the design of a hydraulic cylinder. The base of the hydraulic cylinder were designed and subjected to FEM numerical analyses. The base was made of PET. In addition, a composite cylinder made of wound carbon fibre was subjected to numerical analyses and experimental validation. The numerical calculations were verified in experimental studies. To improve the reliability of the numerical calculations, the material parameters of the composite materials were determined experimentally instead of being taken from the manufacturer’s data sheets. The composite cylinder achieved a weight reduction of approximately 94.4% compared to a steel cylinder (95.5 g vs. 1704 g). Under an internal pressure of 20 MPa, the composite cylinder exhibited markedly higher circumferential strain (4329 μm/m) than the steel cylinder (339.6 μm/m), and axial strain was also greater (−1237 μm/m vs. −96.4 μm/m). Full article

Radial piston motors are expected to expand their applications in hydraulic drive systems due to their high torque density and mechanical robustness. However, its volumetric efficiency can be significantly affected by the multi-stroke operating characteristics and leakage occurring in the micro-clearances of the valve plate. In this study, a detailed modeling procedure for a multi-stroke radial piston motor is proposed using the 1D system simulation software Amesim. In particular, the dynamic interaction between the ports and pistons inside the motor is formulated using mathematical function-based expressions, enabling a more precise representation of the driving behavior and torque generation process. Furthermore, to characterize the leakage flow occurring in the micro-clearance between the fluid distributor and cylinder housing, the commercial CFD software Simerics MP+ was employed to analyze the three-dimensional flow characteristics within the leakage gap. Based on these CFD results, a leakage-path function was constructed and implemented in the Amesim model. As a result, the developed model exhibited strong agreement with reference data from an actual motor in terms of overall operating performance, including volumetric and mechanical efficiencies while consistently reproducing the leakage behavior observed in the CFD analysis. The simulation approach presented in this study demonstrates the capability to reliably capture complex fluid–mechanical interactions at the system level, and it can serve as an effective tool for performance prediction and optimal design of hydraulic motors. Full article

Under the condition of gas–liquid two-phase flow, traditional sucker rod pumps are prone to gas locking due to the high compressibility of gas, and their volumetric efficiency is usually less than 30%, which seriously restricts the exploitation benefits of oil wells. To solve this difficult problem, this study proposes a variable-diameter tube pump structure that adopts an optimized cone angle of the pump cylinder. The results of computational fluid dynamics simulations using dynamic mesh modeling indicate that the stepped change in the pump barrel diameter can enhance the gas–liquid separation effect caused by vortices, while the flow-guiding grooves on the valve seat can reduce the response delay. Comparative calculations and analyses show that compared with the traditional design, its head increases to 13.89 m, and the hydraulic power rises to 1431.01 W, respectively, representing an increase of 17%. This is attributed to the reduction in the gas retention time during piston reciprocation and the stability of the flow field. This structural innovation effectively alleviates the gas lock problem and provides a feasible approach for improving energy efficiency in oil wells prone to vaporization, which is of great significance in oilfield development operations. Full article

Electro-hydraulic servo systems are characterized by significant nonlinearities. Reinforcement learning (RL), known for its model-free nature and adaptive learning capabilities, presents a promising approach for handling uncertainties inherent in such systems. This paper proposes a predefined-time tracking control scheme based on RL, which achieves fast and accurate tracking performance. The proposed design employs an actor–critic neural network strategy to actively compensate for system uncertainties. Within a conventional backstepping framework, a command-filtering technique is integrated to construct a predefined-time control structure. This not only circumvents the issue of differential explosion but also guarantees system convergence within a predefined time, which can be specified independently by the designer. Simulation results and comparisons validate the enhanced control performance of the proposed controller. Full article

The dead-zone input and hydraulic cylinder friction of the pump-controlled automatic gauge control (AGC) system introduce significant challenges to the high-precision rolling of lithium battery pole pieces. To address these nonlinearities, this paper establishes the friction and dead-zone model of the pump-controlled AGC system, and a slide-mode observer is designed to estimate the friction state z in the LuGre model. Furthermore, an adaptive compensation method is adopted to identify the unknown parameters of the input dead-zone and friction models. Meanwhile, combined with the framework of backstepping control design, both matched and mismatched disturbances are effectively compensated. Stability analysis guarantees the convergence of the estimation errors and closed-loop signal boundedness. Finally, experimental results validate the effectiveness and robustness of the proposed control strategy. Full article

To mitigate the inadequate performance of traditional hydraulic systems, mechanical feedback-based digital hydraulic technology is applied to a 3-degree-of-freedom (3-DOF) crane. Digital hydraulic cylinders drive the pitch mechanism, and digital hydraulic motors power the rotary and winch mechanisms. By analyzing the working principles of digital hydraulic cylinders and motors, transfer functions of the 3-DOF actuators are derived. AMESim simulation models are established for each actuator, with model validity verified. Based on these models, simulation analysis of the digital hydraulic system is performed to examine key influencing factors: motor speed, motor subdivision, system flow rate, digital valve opening, and throttle groove shape. System characteristics are obtained, and corresponding optimization schemes are proposed. After optimization, the comprehensive performance of the digital hydraulic system is improved by 1.29%. This study provides theoretical support for the engineering application of digital hydraulic systems in cranes, clarifies their operational specifications and optimization pathways, and exhibits substantial engineering application value. Full article

Vehicle axle load scales are one of the most important devices for vehicle safety testing. To ensure the stability and reliability of test results, regular calibration of axle load scales is necessary. Traditional calibration methods are inefficient and error-prone. In this work, an automatic calibration device for portable axle load scales was presented, which uses a pump-controlled hydraulic cylinder as a loading unit. The loading unit was controlled by a high-precision force sensor and a PLC. A hydraulic unit based on a servo motor and a gear pump was designed, and control software including automatic control, data acquisition, and report generation was developed. The experimental test was carried out. The results showed that the developed portable automatic calibration device could realize the automatic calibration of a 0~150 kN load range, and the accuracy level was up to ±0.3%. Finally, it was verified that the device had the advantages of compactness and lightweight and simple operation. Full article

As a critical component of marine renewable energy, wave energy has long remained a focal point in research on development and use. The Sharp Eagle wave energy converter (hereafter, Sharp Eagle WEC) exhibits wave energy capture efficiency-related advantages, which are attributed to the unique structural configuration of its Sharp Eagle wave-absorbing buoy (hereafter, buoy). Operational observations reveal that under severe sea conditions, buoy motion amplitude increases significantly. Consequently, the downstream hydraulic and power generation systems experience excessive power loads, and the converter exceeds displacement limits, causing collisions with end-stop structures, which compromises operational safety. Research findings indicate that the attitude of the buoy directly governs its motion characteristics. We proposed a ballast-and-load-based attitude control method for the buoy. This approach provides safe and efficient operation across all sea conditions. Via scaled model tests, converter operational data covering various ballast configurations were compared and analyzed, focusing on the effects of ballast on the capture width ratio (hereafter, CWR) and piston displacement range of energy conversion hydraulic cylinders. Herein, the feasibility of adjusting capture efficiency and motion displacement by controlling the buoy attitude is validated, providing a technical framework for efficient and safe operation of the WEC under all sea conditions. Full article

A collaborative control strategy combining the hyperbolic sine-cosine optimization (SCHO) algorithm with fuzzy adaptive linear active disturbance rejection control is proposed to address the nonlinearity and uncertainties in the hydraulic position servo system of shock absorber test benches. First, based on the dynamic characteristics of the shock absorber fatigue test bench and the tested shock absorber, a linearized model of the valve-controlled hydraulic cylinder and its load was established. The coupling mechanism of system parameter perturbation and disturbance was also analyzed. A third-order LADRC (Linear Active Disturbance Rejection Control) was designed considering the linear model characteristics of the test bench hydraulic servo system model to quickly estimate internal system disturbances and perform real-time compensation. Secondly, a multi-objective optimization function was constructed by integrating system performance indicators and incorporating controller and observer bandwidths into the optimization objectives. The SCHO algorithm was used for the global search and optimization of key LADRC parameters. To enhance the controller’s adaptive capability of modeling uncertainties and external disturbances, a fuzzy adaptive module was introduced to adjust control gains online according to errors and their rates of change, further improving system robustness and dynamic performance. The results show that compared with traditional PID, under different working conditions, the proposed method reduced the maximum tracking error, overshoot, and system response time by an average of 45%, from 15% to 5%, and by approximately 30%, respectively. Meanwhile, the parameter combination obtained via SCHO effectively avoids the limitations of manual parameter tuning, significantly improving control accuracy and energy utilization. The simulation results indicate that this method can significantly enhance position-tracking accuracy compared with traditional LADRC, providing an effective solution for position-tracking control in hydraulic servo testing systems. Full article

This study presents the design and validation of an automated skip loading system for vertical shaft hoisting operations, aimed at addressing inefficiencies in current manual systems that contribute to consistent underperformance in meeting daily production targets. Initial assessments revealed a task completion rate of 91.6%, largely due to delays and inaccuracies in manual ore loading and accounting. To resolve these challenges, an automated system was developed using a bin and conveyor mechanism integrated with a suite of industrial automation components, including a programmable logic controller (PLC), stepper motors, hydraulic cylinders, ultrasonic sensors, and limit switches. The system is designed to transport ore from the draw point, halt when one ton is detected, and activate the hoisting process automatically. Digital simulations demonstrated that the automated system reduced loading time by 12% and increased utilization by 16.6%, particularly by taking advantage of the 2 h post-blast idle period. Financial evaluation of the system revealed a positive Net Present Value (NPV) of $1,019,701, a return on investment (ROI) of 69.7% over four years, and a payback period of 2 years and 11 months. The study concludes that the proposed solution significantly improves operational efficiency and recommends further enhancements to the hoisting infrastructure to fully optimize performance. Full article

This study aims to assess the effect of vegetation angle and density on hydrostatic pressure and acceleration of a downstream house model experimentally. The vegetation cylinders were positioned at angles 30°, 45°, 60° and 90° with respect to the flow and two densities of vegetation conditions, i.e., sparse (G/d = 2.13) and intermediate (G/d = 1.09), where G is the spacing between the model vegetation elements in the cross-stream di-rection and d is the vegetation diameter. The streamwise acceleration of the house model was measured by an X2-2 accelerometer that was located downstream from the vegetation patches. Results show that the perpendicular orientation of the vegetation patch (90°) most effectively reduces hydrodynamic loads, with intermediate density (I90) achieving the highest reductions, i.e., 22.1% for acceleration and 7.4% for pressure impacts. Even sparse vegetation (S90) provided substantial protection, reducing acceleration by 21.9% and pressure by 5.8%. These findings highlight the importance of integrating vegetation density and orientation into flood management designs to enhance both their performance and reliability under varying hydraulic conditions. Full article