Guofang Gong

Self-tuning-parameter fuzzy PID temperature control in a large hydraulic system

Oil temperature control in a large hydraulic system is dealt with using the fuzzy logic control algorithm. Mathematic model of the control system characterized by large time delay is created based on law of thermodynamics. A self-tuning-parameter fuzzy PID controller is designed to regulate the cooling water flow rate through the triple proportional valve in order to control the oil temperature. The simulations and experiments are carried out, making a comparison with conventional PID control. The results suggest that fuzzy PID strategy can efficiently improve the performance of the hydraulic temperature control system, irrespective of time delay problem and parameter variations. It achieves higher control accuracy of temperature, faster response and stronger robustness than conventional PID control system.

The Development of a High-Speed Segment Erecting System for Shield Tunneling Machine

The present study is focused on developing an effective high-speed segment erecting system, which is specific for modern shield tunneling machine. The big steady-state error and large impact force caused by high motion speed and large inertia load are main restrictions for the conventional segment erector to realize high-speed segment erecting. To overcome the bottleneck, a new hydraulic system that is based on electrohydraulic proportional control technology is designed, the actuator speed of which is adjustable and controllable. The kinematic and dynamic models are established to determine the displacement of each actuator and calculate joint force, respectively. A combined motion law is then selected to reduce joint force during acceleration and deceleration stages. Furthermore, a superior control strategy that is able to precisely and smoothly control the segment erector at high speed is chosen by comparing the experimental performances of four different control strategies. Experiments are carried out on a segment erector test rig. The experimental results show exceptional performances of the speed and position compound control system in terms of accuracy and impact force. The maximum rotation speed of the new system can be increased to more than three times of that of the present erecting system. In addition, high steady-state accuracy can be achieved with the new system while its impact force is just about one-third of the position control system.

Control of bulk modulus of oil in hydraulic systems

In view of requirements for better position accuracy, response time and stability of hydraulic system, it is more important than ever to pay attention to bulk modulus of hydraulic oil. In this paper, the effects of the bulk modulus of hydraulic oil on system performance and the entrapped air on bulk modulus have been analyzed. A method of online vacuum degassing in a sealed system has been used to increase the effective bulk modulus of hydraulic oil, and a device has been developed to measure oil bulk modulus online. The experimental results show that the bulk modulus of hydraulic oil can be controlled in real system effectively by the method mentioned above.

Positioning speed and precision control of a segment erector for a shield tunneling machine

This paper deals with a positioning speed and precision control system for the assembly of segments of a shield tunneling machine. First, we design a six degrees of freedom segment erector with electrohydraulic drive. Then, the segment positioning process and the dynamics model of the electrohydraulic system are analyzed theoretically. Segment positioning control system is designed, making comparisons between speed and displacement/angle control in terms of efficiency and precision. Several reference speed run curves are selected to control the segment positioning process. Simulations are carried out to achieve the selected optimal run speed of the segment. The simulation results verify the validity of the proposed control system.

Position and Attitude Precision Analysis of Segment Erector of Shield Tunneling Machine

Focusing on a segment erector of a shield tunneling machine developed with 6 degrees of freedom and controlled by electro-hydraulic proportional systems, kinematics for the segment erection process is presented. The perturbation method in error analysis is introduced to establish the position and attitude error model, considering a number of factors such as hydraulic drive and control accuracy, tolerance in manufacturing and assembly. Dynamic simulations are carried out to obtain the controlling precision of the electro-hydraulic drive systems. Formulas for calculating the position and attitude error of the grip hand of the segment erector are derived. The calculation results verify the practicality and effectiveness of error analysis, providing a foundation for practical designing, manufacturing and assembling of the segment erecting mechanism.

Pressure and speed control of electro-hydraulic drive for shield tunneling machine

This paper presents an electro-hydraulic control system for shield thrust drive. The control model of thrust system is developed. A pressure and flow compound control approach is applied using the pressure and flow rate feedback to design an outer loop controller and an inner loop controller to address the control problem encountered in thrust, cooperating with the pressure relief valve and the flow control valve. Simulation and field application results are presented to verify the effectiveness and rationality of the proposed drive system and its control approach.

An Investigation in Performance of a Variable-Speed-Displacement Pump-Controlled Motor System

This paper is focused on investigating in the performance of a variable-speed-displacement pump-controlled motor system (VSDPM). As one key performance parameter, VSDPMs rated operating space is investigated through system model and numerical calculation. For comparison and analysis, two other typical systems’ rated operating spaces are also calculated. As another key performance parameter, VSDPMs efficiency is studied through experiments. Given that VSDPMs efficiency changes with its displacement, the efficient displacement is first searched. With the efficient displacement, we then measure VSDPMs efficiency over its calculated operating space. Besides, the efficiency of a variable-displacement pump-controlled motor system (VDPM) is also measured as a contrast. Through comparative analysis, we find that VSDPM can achieve a better efficiency performance at low speed and low torque. Compared to VDPM, its efficiency increment can be up to 11.5%. But VDPM performs better at high speed. Compared to VSDPM, its efficiency increment can be up to 4.8%. Finally, VSDPMs stand-by energy consumption is measured. While at stand-by mode, VSDPM consumes little power which is only 3% of VDPMs consumption.

Novel electro-hydraulic position control system for primary mirror supporting system

In the field of modern large-scale telescope, primary mirror supporting system technology faces the difficulties of theoretically uniform output force request and bias compensation. Therefore, a novel position control system combining hydraulic system with servo motor system is introduced. The novel system ensures uniform output force on supporting points without complicating the mechanical structure. The structures of both primary mirror supporting system and novel position system are described. Then, the mathematical model of novel position control system is derived for controller selection. A proportional–derivative controller is adopted for simulations and experiments of step response and triangle path tracking. The results show that proportional–derivative controller guarantees the system with micrometer-level positioning ability. A modified proportional–derivative controller is utilized to promote system behavior with faster response overshoot. The novel position control system is then applied on primary mirror supporting system. Coupling effect is observed among actuator partitions, and relocation of virtual pivot supporting point is chosen as the decoupling measurement. The position keeping ability of the primary mirror supporting system is verified by rotating the mirror cell at a considerably high rate. The experiment results show that the decoupled system performs better with smaller bias and shorter recovery time.

Synchronization Control of Torque Cylinders for Hard Rock Tunnel Boring Machine

A synchronization control systemSCS is proposed to reduce synchronization deviation of left and right torque cylinders in vertical steering of hard rock tunnel boring machineTBM. Hydraulic system based on proportional valves is designed after the introduction of attitude mechanism. Establishing the load model of torque cylinders, this paper carried out simulation comparison between SCS and traditional displacement control systemDCS. The results show that the deviation in SCS is 1.5 mm and 6 mm in DCS. Synchronization control system has a significant effect on reducing displacement deviation of left and right torque cylinders.

Coordination control for parallel actuation of hydraulic power assisted ball screw drive system

Hydraulic actuators are commonly incorporated into the vertical feed drive system of heavy duty machine tools to achieve higher load capacity and stiffness by balancing the moving load. In the linear motion control system with ball screw and cylinder driving in parallel, interactions between two drive sets are directly related with machining accuracy. On one hand, motion synchronization should be dealt with in term of master and slave scheme with hydraulic cylinder following the speed generated by screw nut real-timely. On the other hand, temperature rise due to heat generation of moving parts causes not only thermal expansion of the screw shaft but also property change of hydraulic oil, finally exerting a significant influence on the positioning accuracy. In this paper, the coupled model of this combination is built up to analyze the dynamic performance under different operating conditions. Based on the electromechanical system model with hydraulic dynamics and thermal dynamics, the problem is formulated as coordinating the velocity of two actuation systems with coupling. The hydraulic actuator is modeled as a combination of an ideal velocity source and a spring for modeling the compressibility effects of the fluid medium to address the coordination control issue. It is shown in the simulation results that the proposed control strategy can achieve desired coordination of different drive systems with acceptable tracking errors.