Hydraulic systems

ABSTRACT The paper presents design, simulation, implementation and testing of an inductive displacement sensor based on a Linear Variable Differential Transformer (LVDT) controlled by a single chip electronic module with 16 bit RISC microcontroller. LVDT device is widely used in hydraulic and pneumatic mechatronic systems for measuring physical quantities like displacement, force or pressure; it consists of two magnetic coupled coils with a common moving core; its displacement is converted in reluctance variation of magnetic circuit. Standard electronics for LVDT sensor conditioning is analog - quadrate oscillator, synchronous demodulator and amplifiers - but has its drawbacks - relative complex, hard to adjust, many components and packages, no connection to computer systems. The originality aspects of the work come from the unique method of finding displacement information by switching supply voltage in the coils of inductive device. This method uses only peripherals from a microcontroller so is low cost and easy to adjust. Present paper focuses on modelling and simulation of displacement measuring method but analyzes also implementation aspects for a real application (an electro hydraulic position control system).

One of the most advantages of hybrid vehicles is that the wasted braking energy can be captured and reused during driving cycle. In this paper, a regenerative braking system for hydraulic hybrid vehicles is investigated. Based on Matlab/Simulink, the model ...

Abstract—In the forest industry, trees are logged and har-vested by human-operated hydraulic manipulators. Eventually, these tasks are expected to be automated with optimal per-formance. However, with todays technology the main problem is implementation. While ...

This paper deals with a comparative study on using water and air as actuation means for the control of a fluidic muscle (designed for air) and assesses the performance, particularly from a dynamic and energetic point of view. A medium with higher bulk modulus such as oil/water is believed to increase pressure and force bandwidths and reduce sensitivity to load variations, as is the case with conventional hydraulic stiff actuation systems. However in this application the inherent flexibility of the muscle plays a major role. Water has been chosen because of its non-flammability, environmental friendliness and the low solubility of air in it. The operating pressure range of the pneumatic muscle is 0-6 bar (typical range of a pneumatic system) that is well below typical operating pressures of hydraulic systems (typically over 100 bar). At such low pressures the dynamic behaviour of water is less predictable because of the higher likelihood of entrapped air in the water which physically occurs when operating at low pressures. This can majorly affect water bulk modulus and hence its dynamic performance. Therefore, the behaviour of the system in this unconventional pressure range for a liquid must be more thoroughly investigated. Theoretical and experimental analyses on a dedicated test rig have been carried out to assess these assumptions.

... Chun-Liang Lin , Chun-Hsiung Chen , Van-Tsai Liu3 and Thong-Shing Hwang4 1. Department of Electrical Engineering, National Chung Hsing University, Taichung, Taiwan 402, ROC 2. Institute of Electrical and Information Engineering, Feng Chia University, Taichung, Taiwan ...

Open channel flow systems are known to be described by non-linear partial differential equations (Saint-Venant equations), but a simple finite-dimensional model has been successfully developed for control purposes in a previous work, using a collocation method. In particular, a control law based on Input/Output linearization has been proposed on this basis. In the present note, it is pointed out how the considered model is actually fully feedback linearizable, and how a state feedback controller only using two level measurements and one flow measurement along the canal can result from this so-called flatness property. Performances of this controller are illustrated by simulation results.

For the improvement of the precision engineering, a precision motion is one of the key issues. The goal of this paper is to establish a precision stage. Four linear motors are used to establish a noncontact table to avoid the influence of friction, and a two-dimensional planar encoder is employed as feedback sensors. In order to accomplish ultra precision motion, a PDFF (pseudo derivative feedback with feed-forward) controller is used. Compared with normal PI controller, simulation results show that the PDFF controller can perform better than PI controller not only in running a step motion but also in running a dynamic trajectory.

This paper presents the application of extended Kalman filter (EKF) to closely estimate the states of hydraulic systems. The EKF, working concurrently with the actual system, accepts the input voltage signal to the servovalve and the measurements of the cylinder chamber pressures, and then rebuilds the system states. The spool displacement of the servovalve, the chamber pressures of the actuator

Hydraulic systems are widely used in industrial applications. This is due to its high speed of response with fast start, stop and speed reversal possible. The torque to inertia ratio is also large with resulting high acceleration capability. The nonlinear properties of hydraulic cylinder make the position tracking control design challenging. This paper presents the development and implementation of self-tuning fuzzy PID controller in controlling the position variation of electro-hydraulic actuator. The hydraulic system mathematical model is approximated using system identification technique. The simulation studies were done using Matlab Simulink environment. The output performance was compared with the design using pole-placement controller. The roots mean squared error for both techniques showed that self-tuning Fuzzy PID produced better result compared to using pole-placement controller.

The main objective of vehicle powertrain hybridization is to simultaneously improve the fuel consumption and environment pollutants impact (Eco-score) without decreasing the vehicle performances and other user satisfaction criteria. Based on a simulation model in ADVISOR, one can evaluate the performances, the emissions and then the Ecoscore and the user satisfaction for different driving scenarios. To establish a rationale methodology for assessing the eco-efficiency character, we adopt a multidisciplinary optimization approach while minimizing / maximizing both Eco-score and user satisfaction objective functions. The proposed approach is then used to establish a comparison between HEV (hybrid electric vehicle) and HHV (hybrid hydraulic vehicle) configuration by highlighting the effect of different energy storage systems (batteries, ultra capacitors, hydraulic system), mechanical and electric components sizes upon the optimized HEV design. The selected application is the comparison of different mild parallel hybrid buses. Results show that the hybrid electric buses using ultra capacitors have almost the same performances as those using batteries, while the HHV technology can compete with HEV because of the hydraulic components low cost and recyclability if possibly using of water as motor/pump fluid.

This paper describes simple physical hydraulic laboratory models that are able to communicate with computer via both the standard USB interface and through converter cards. They show to be appropriate for evaluating different control approaches to linear and nonlinear controllers design and for demonstrating basic control features in both university laboratories as well as via Internet.