Junpeng Shao

Bio: Junpeng Shao is an academic researcher from Harbin University of Science and Technology. The author has contributed to research in topics: Bearing (mechanical) & Thrust bearing. The author has an hindex of 9, co-authored 39 publications receiving 237 citations.

A compound control strategy combining velocity compensation with ADRC of electro-hydraulic position servo control system.

Abstract: In order to enhance the anti-jamming ability of electro-hydraulic position servo control system at the same time improve the control precision of the system, a compound control strategy that combines velocity compensation with Active Disturbance Rejection Controller (ADRC) is proposed, and the working principle of the compound control strategy is given. ADRC controller is designed, and the extended state observer is used for observing internal parameters uncertainties and external disturbances, so that the disturbances of the system are suppressed effectively. Velocity compensation controller is designed and the compensation model is derived to further improve the positioning accuracy of the system and to achieve the velocity compensation without disturbance. The compound control strategy is verified by the simulation and experiment respectively, and the simulation and experimental results show that the electro-hydraulic position servo control system with ADRC controller can effectively inhibit the external disturbances, the precise positioning control is realized after introducing the velocity compensation controller, and verify that the compound control strategy is effective.

The Effect of Oil Cavity Depth on Temperature Field in Heavy Hydrostatic Thrust Bearing

Abstract: For a heavy hydrostatic bearing with a high linear velocity, the results of numerical calculations often differ from practical conditions if the viscosity is considered as constant. In this article, the influence of the oil cavity depth on the temperature field in the heavy hydrostatic bearing is discussed in the context of variable viscosity. The viscosity-temperature relations for the gap oil film are first established by fitting B-Spline curves, then, numerical calculations for the temperature field in the heavy hydrostatic bearing of different oil cavity depths are carried out based on Finite Volume Method (FVM) under the same rotating speed, and the influence of the oil cavity depth on the temperature distribution in the gap oil film of the hydrostatic bearing is discussed. The results of numerical calculations provide the temperature distribution state inside the hydrostatic bearing, which would help the selection and the design of hydrostatic bearings in engineering practice.

Model Identification and Control of Electro-hydraulic Position Servo System

Abstract: In view of introduction of the composition and working principle of the electro-hydraulic position servo control system, the mathematical model of the system was built. In order to acquire more accuracy system mathematical model, System model identification and verification of electro-hydraulic position servo system were carried out based on hardware-in-the-loop simulation environment of Real-time Workshop (RTW) and system identification toolbox in MATLAB. A hybrid controller composed of a proportional controller, a fuzzy controller and a classical PID controller, for which the parameters of the PID controller can be adjusted online by using the fuzzy control rule, The zero position of fuzzy domain was regarded as the switching threshold, and stable switching is implemented between the proportional control and the proportion-fuzzy PID control. The simulation results show that the steady-state error of system is eliminated, the rapidity is enhanced by the hybrid control strategy, Moreover, and its ability of adapting to system parameter variation is superior to the other controllers.

Simulation of embedded heat exchangers of solar aided ground source heat pump system

Abstract: Aimed at unbalance of soil temperature field of ground source heat pump system, solar aided energy storage system was established. In solar assisted ground-source heat pump (SAGSHP) system with soil storage, solar energy collected in three seasons was stored in the soil by vertical U type soil exchangers. The heat abstracted by the ground-source heat pump and collected by the solar collector was employed to heating. Some of the soil heat exchangers were used to store solar energy in the soil so as to be used in next winter after this heating period; and the others were used to extract cooling energy directly in the soil by circulation pump for air conditioning in summer. After that solar energy began to be stored in the soil and ended before heating period. Three dimensional dynamic numerical simulations were built for soil and soil heat exchanger through finite element method. Simulation was done in different strata month by month. Variation and restoration of soil temperature were studied. Economy and reliability of long term SAGSHP system were revealed. It can be seen that soil temperature is about 3 °C higher than the original one after one year’s running. It is beneficial for the system to operate for long period.

Study of the electro-hydraulic load simulator based on double servo valve concurrent control

Abstract: The superfluous force exists in the electro-hydraulic servo rudder load system, and seriously affects the dynamic load precision of the system. Meanwhile, the superfluous force makes the stability of the system bad, let frequency width dwindle, and reduces the load sensitivity of the system. Aiming at these questions and in order to improve the control performance of the load system of the electro-hydraulic load simulator, furthermore, for the sake of solving the superfluous force this technical problem caused by the forced flow, the author proposes the method of adopting the flow servo valve and the flow-press servo valve concurrent control the electro-hydraulic load simulator load system. This method makes the flow-press servo valve as a flow compensation tache, and changes the electro-hydraulic force servo system with strong position disturbance to the electro-hydraulic force servo system without disturbance. Then the author studies the electro-hydraulic force servo system on building its model, simulation and experiment and the result of the study shows that the superfluous force obviously decrease when the double valve concurrent control method adopted to the load system. At the same time, the dynamic load precision of the load system is obviously improved.

Recent Progress on Magnetorheological Solids: Materials, Fabrication, Testing, and Applications†

Abstract: Magnetorheological (MR) materials are classified as smart materials due to their responsiveness to external magnetic stimuli. Intensive research on MR materials has led to broad applications in several potential fields. A solid carrier matrix state called MR elastomer with its exceptional magnetic responsive feature is obtained by merging magnetizable particles within an elastomeric polymer. This integration results in outstanding characteristics on the rheological performances. Special prominence is given to the understanding of the base materials and fabrication as well as the functional behavior through various characterization methods. Broad applications of MREs are also explored to provide a profound market picture and to motivate researchers to develop novel technology. The functional behavior of MREs is briefly explained. The art of the materials provides the current position and mapping of the matrix and filler particles. Types of matrix and particles are mentioned together with the level of the research interest on MREs. Description of the fabrication is provided in simple diagrams as summarized from previous works to enhance the MREs performance. The possible tests to reveal the characteristics of the MREs are delivered with the global experimental setup. The review also explains the applications of MREs as well as discussion on the MREs future promising applications.

A hydraulic control system

Abstract: A hydraulic control system for controlling at least one load (1; 30, 40), the respective load pressure as a load-sensing signal via a respective load-sensing line (LS - that as a means for influencing a load-sensing signal, a compensator (10) is present, a corrected load sensing signal (LS - that the compensator (10) consists of a compensation valve (11) and a shut-off valve (12), - that the compensation valve (11) comprises a pressure applied to it load-sensing pressure (p - that the shut-off valve (12) shuts the compensator (10) when at the compensation valve (11) pending load-sensing pressure (p