By analyzing the shortcomings of the traditional fuzzy PID(Abbreviation for Proportional, Integral and Differential) control system (FPID), a multiple fuzzy PID suspension control system based on road recognition (MFRR) is proposed. Compared with the traditional fuzzy PID control system, the multiple fuzzy control system can identify the road grade and take changes in road conditions into account. Based on changes in road conditions and the variable universe and secondary adjustment of the control parameters of the PID controller were carried out, which makes up for the disadvantage of having too many single input parameters in the traditional fuzzy PID control system. A two degree of freedom 1/4 vehicle model was established. Based on the suspension dynamic parameters, a road elevation algorithm was designed. Road grade recognition was carried out based on a BP neural network algorithm. The experimental results showed that the sprung mass acceleration (SMA) of the MFRR was much smaller than that of the passive suspension system (PS) and the FPID on single-bump and sinusoidal roads. The SMA, suspension dynamic deflection (SDD) and tire dynamic load (TDL) of the MFRR were significantly less than those of the other two systems on roads of each grade. Taking grade B road as an example, compared with the PS, the reductions in the SMA, SDD and TDL of the MFRR were 40.01%, 34.28% and 32.64%, respectively. The control system showed a good control performance.

The flow-matching problem of hydraulic systems is an important factor affecting the working performance and energy saving of hydraulic systems. According to the different flow-matching mechanisms, the flow-matching technology of hydraulic systems can be divided into three categories: positive flow-control technology, negative flow-control technology, and load-sensitive control technology. In this paper, the working mechanism of flow-matching technology and the cause of energy loss are analyzed, and the research results of flow matching are introduced from two aspects of energy saving and consumption reduction and system performance improvement. In the direction of energy saving and consumption reduction, the purposes of energy saving and consumption reduction are achieved by means of multi-way valve commutation, independent inlet and outlet control, parallel replacement of shuttle valve by a cylinder piston rod controlled by pilot pressure, change of hydraulic resistance of a pressure compensating valve, improvement of the power regulation range of a hydraulic pump, and potential energy recovery. In the direction of system performance, by means of flow-forecasting system pressure change, applying flow unsaturation real-time control idea, and combining electronic control technology with load-sensitive technology, the pressure drop during transmission process and the transmission signal lag are reduced, the speed regulation interval is enlarged, fine-tuning characteristics are improved, and the response speed is increased. The research results indicate that improving the structure and the control strategy of hydraulic systems and improving the flow-matching degree of a system to achieve global matching will be a future development trend.

Hydraulic control valves are widely used in industrial production, agricultural equipment, construction machinery, and other large power equipment for controlling the pressure and flow of fluids in hydraulic systems. The driving method has a significant impact on the response and control accuracy of hydraulic valves. This paper reviews the driving methods of spools from five aspects: solenoid drive, material expansion drive, motor drive, hydraulic valve drive, and another drive. It summarizes the various schemes currently available for spool drive and analyzes each of them. After optimizing the driving method of the valve core, the control accuracy can reach 3%, and the minimum response time is 7 ms. According to the characteristics of the different drive methods, the differences between them are compared, the advantages and disadvantages of each drive method are analyzed, and the application scenarios for each drive method are identified. Solutions to the drawbacks of the existing drive methods are proposed, which provide directions for further optimization. We have found that solenoid drives are simple to control, low cost, and the most widely used. Material telescopic drives, motor drives, hydraulic valve drives, and other drives are costly, complex to control, and optional for use in special requirement situations. Based on the existing spool drive methods, an outlook on future drive methods is presented. This review facilitates a comprehensive understanding of the drive methods of hydraulic valve spools, points out the shortcomings of the existing drive methods, and is of great significance in improving the existing drive methods and proposing new drive methods. This paper has a positive effect on improving the control accuracy and responsiveness of hydraulic valves.

The hydraulic force has a great negative effect on the cartridge poppet valve system. Based on the law of momentum, the calculation formula of flow force of outflow poppet valve is modified, and a new valve core structure is designed. The compensation effect of the improved main valve core structure on the hydraulic force is discussed; secondly, CFD simulation is carried out to obtain the influence rules of these parameters on hydrodynamic forces. According to the analysis, the influence of main valve core arc structure on hydrodynamic force compensation under different opening degrees is also studied; then the optimal parameters of the arc structure are obtained through analysis. AMEsim system simulation model and test-bed are built to verify the hydrodynamic formula and simulation results. The experimental results verify that the new valve core structure has a good hydrodynamic compensation effect.

In many different industrial domains, hydraulic control systems are extensively utilized. This paper examines the current state of research and the trajectory of energy-efficient hydraulic control system development. Initially, a quick introduction to the control principles of hydraulic control systems is given. Secondly, hydraulic control systems are classified, the factors affecting the energy consumption of hydraulic control systems are analyzed, and the method of reducing its influence on hydraulic control systems is given. Subsequently, research concerning energy conservation is compiled based on the classification of hydraulic control systems. In this paper, the circuit structure of two control modes of a hydraulic control system (valve control system and pump control system) and their related control algorithms (fuzzy PID control, adaptive robust control) for reducing system energy consumption are studied. In summary, the evolution of energy-efficient hydraulic control system approaches is forecasted and projected, offering some pointers for advancing hydraulic control system study and implementation in the industrial future.

As one of the important factors affecting the stability of slide valves, the analysis and research of flow force are of great significance. In recent years, more and more experts and scholars have conducted research in this field, attempting to find methods to reduce or utilize the flow force of hydraulic spool valves. Flow force includes steady-state flow force and transient flow force, with steady-state flow force having the most significant impact on spool valves. The influencing factors of flow force are complex and diverse, including the cavitation phenomenon, shape of the throttling groove, and jet angle. At present, the main ways to reduce flow force are to design the structure of the spool valve, the structure of the valve sleeve, and the flow channel of the valve body. This article mainly reviews the definition, calculation methods, influencing factors, and methods for reducing the flow force of slide valves. This provides a new approach to reducing the flow force in hydraulic spool valves.