International Journal of Hydromechatronics (5 papers in press)

Regular Issues

• Quantitative analyses of the influence of practical aspects on hydraulic force control performance  
  by Elisa G. Vergamini, Cícero Zanette, Lucca Maitan, Leonardo F. Dos Santos, Marcos P. Nostrani, Thiago Boaventura 
  Abstract: Hydraulic actuators are a strong alternative for robotics, offering high mobility and a favourable power-to-weight ratio. However, in many industrial and robotic applications, key system parameters - such as oil temperature, hose length, supply pressure, valve bandwidth, and control frequency - can vary over time due to operational demands, wear, or environmental conditions. Despite their importance, the impact of these variations on force control performance is often underestimated. This study investigates how such parameters affect the performance of a standard PI force controller in hydraulic actuators. Using the IC2D test bench, experiments were performed with different servovalves (Moog E024 and G761) and parameters setups. Results show that pressure level and hose length significantly impact controller performance, while valve model produces less predictable effects. Control frequency has little influence. Interestingly, temperature affected force tracking in unexpected ways, with valve opening and flow rate playing a more dominant role.
  Keywords: practical aspects; hydraulic actuators; servovalves; force control performance; hydraulic force; oil temperature; hose length; valve bandwidth; control frequency; supply pressure.
  DOI: 10.1504/IJHM.2025.10072847
   
  
• Design of bearings load uniform structure and study on load uniform effect of submersible screw pump  
  by Rui Dong, Zhiqiang Wang, Beilin Han, Salvinder Singh Karam Singh, Chenxu Chen, Tianxing Tu 
  Abstract: The submersible screw pump (SSP) is widely utilised due to its low cost, high energy efficiency, and exceptional pumping performance. However, under high-speed and heavy-load operating conditions, key components such as bearings experience significant axial loads, which lead to reduced bearing lifespan and reliability. To enhance bearing lifespan and reliability, this study combines both simulation and experimental approaches to design a multi-stage bearing load uniform structure. Simulation analysis was performed on components such as disc springs. The results indicate that the multi-stage bearing load uniform structure can effectively uniform axial loads. The study also identifies that factors, such as the gap between the disc spring and the bearing as well as assembly gaps, negatively impact load uniformity. Therefore, this research offers an effective design strategy for the structural optimisation of SSPs, contributing to improved bearing group lifespan and reliability.
  Keywords: submersible screw pump; bearings load uniform structure; multi-stage bearings; load uniform effect.
  DOI: 10.1504/IJHM.2025.10072877
   
  
• Fuzzy PID Control Strategy Optimised by Sparrow Search Algorithm for Digital Proportional Valve with Differential Control of Dual High-Speed On/Off Valves  
  by Chunjie Xu, Fangwei Xie, Zuzhi Tian, Ziyan Zhao, Zibo Chen, Yumeng Li 
  Abstract: This study explores the potential of pilot-controlled digital valves in balancing high flow rates and fast response, focusing on suppressing spool oscillations for precise position control. A prototype and multi-physics simulation model of a digital proportional valve with differential control of dual high-speed on/off valves are developed. The motion characteristics of main spool under varying control frequencies and duty cycles are analysed. A differential control method to reduce oscillation is proposed, along with a fuzzy PID control strategy optimized by the sparrow search algorithm to adaptively adjust the duty cycle difference. Simulation results show that, under the SSA-FPID control, the valve spool position step response rise time decreases by 38.2%, the steady-state average absolute error reduces by 16.1%, and the tracking error under typical excitations is under 0.1 mm. Experimental verification confirms the effectiveness of the control strategy, offering insights for valve design, optimisation, and control.
  Keywords: Digital proportional valve; spool oscillation characteristics; high-speed on/off valve; differential control; fuzzy PID; sparrow search algorithm.
  DOI: 10.1504/IJHM.2025.10073232
   
  
• Wear Defect Detection of Hydraulic Pump using a Hybrid Method of VGG and LSTM  
  by Shengnan Tang, Yixuan Jiang, Hong Su, Kian Meng Lim, Zhijian Zheng, Yong Zhu 
  Abstract: Hydraulic pump is an important power element among the core components of the hydraulic transmission system in mechanical equipment. The concealment of typical faults in hydraulic pumps makes accurate fault detection challenging. Fault signals are typically temporal, and this paper proposes an intelligent method based on Synchrosqueezing Wavelet Transform (SWT) and an improved fusion model. The method fully incorporates (i) SWT to improve the time-frequency separation of fault information, (ii) deep feature extraction from image information of VGG, and (iii) Long Short-Term Memory (LSTM) to control network information transmission and optimise memory stacking methods of the network to achieve high-precision fault detection. The proposed hybrid VGG-LSTM is evaluated by analysing pressure signals from the hydraulic pump. Compared with other models, the proposed model has excellent fault recognition ability with minimum error and standard deviation, which proves that the theory of fusion reconfiguration network is reasonable.
  Keywords: hydraulic pump; convolutional neural network; defect detection; long short-term memory.
  DOI: 10.1504/IJHM.2025.10073233
   
  
• Investigation of Non-Homogeneous Thick-Walled Cylinder Ceramic Matrix Composites (CMCs) for Biochemical and Medical Innovations  
  by Pankaj Thakur, Priya Gulial 
  Abstract: This study investigates thick-walled cylinder Ceramic Matrix Composites (CMCs) in biochemical and medical applications. High-performance materials, such as Zirconia (ZrO2)-based and Alumina (Al2O3)-based composites, are identified as optimal for high-stress biomedical applications due to their exceptional pressure resistance. Conversely, lightweight composites, including Boron Carbide (B4C)-based and Silicon Carbide (SiC)-based materials, are highlighted as cost-effective and well-suited for low-load medical devices. The research emphasizes the relationship between wall thickness and surface pressure, alongside the importance of stress distribution in determining material performance. The findings advocate for strategic material selection and design optimisation to enhance the safety, performance, and durability of medical devices across diverse operational conditions.
  Keywords: Thick-Walled Cylinder; Ceramic Matrix Composites; Biochemical Applications; Medical Device Performance; Stress Distribution; Material Optimization.
  DOI: 10.1504/IJHM.2025.10073291