Experimental comparison between proportional and PWM-solenoid valves controlled servopneumatic positioning systems

The performance of the Dynamical Adaptive Backstepping-Sliding Mode Control (DAB-SMC) scheme for positioning of a pneumatic cylinder regulated by two types of PWM-solenoid valves is experimentally investigated. The goal is to study the compromise in controller’s performance as the system moves from using a proportional valve to employing the low-cost PWM-solenoid valves. Sinusoidal and multiple-step inputs are used as the reference position trajectories. Experimental results show that the DAB-SMC scheme works best with the proportional valve. The performance, however, deteriorates by more than twofold, once the system utilizes PWM- solenoid valves of 3/2-way or 2/2-way configurations. From this study, tradeoff between performances of different types of valves applied on a DAB-SMC scheme-controlled servo positioning system is successfully documented. This information helps to configure appropriate servopneumatic system for positioning applications

Development and operation of research-scale III-V nanowire growth reactors

III-V nanowires are useful platforms for studying the electronic and mechanical properties of materials at the nanometer scale. However, the costs associated with commercial nanowire growth reactors are prohibitive for most research groups. We developed hot-wall and cold-wall metal organic vapor phase epitaxy (MOVPE) reactors for the growth of InAs nanowires, which both use the same gas handling system. The hot-wall reactor is based on an inexpensive quartz tube furnace and yields InAs nanowires for a narrow range of operating conditions. Improvement of crystal quality and an increase in growth run to growth run reproducibility are obtained using a homebuilt UHV cold-wall reactor with a base pressure of 2 X 10$^{-9}$ Torr. A load-lock on the UHV reactor prevents the growth chamber from being exposed to atmospheric conditions during sample transfers. Nanowires grown in the cold-wall system have a low defect density, as determined using transmission electron microscopy, and exhibit field effect gating with mobilities approaching 16,000 cm$^2$(V.s).Comment: Related papers at http://pettagroup.princeton.ed

Dynamics of Hydraulic System with Proportional Valve

Diplomová práce se zabývá dynamikou hydraulického systému s proporcionálním rozváděčem. V teoretické části práce jsou popsány statické a dynamické charakteristiky, proporcionální technika a pohybová rovnice šoupátka proporcionálního rozváděče. V praktické části je navržený a sestavený hydraulický obvod pro měření statických a dynamických charakteristik proporcionálního rozváděče. Hydraulický obvod je navržen včetně všech snímačů. Sestavení matematického modelu proporcionálního rozváděče a následná simulace byla provedena v programu Matlab Simulink. V závěrečné části je porovnána simulace matematického modelu s měřením na experimentálním obvodu.Master thesis deals with dynamic of hydraulic system with proportional valve. In theoretical part are described static characteristics and dynamic characteristics, proportional technique and motion equation of proportional valve. In practical part is designed and assembled a hydraulic system for measurements of static and dynamic characteristics of proportional valve. Hydraulic system is designed including all sensors. Build a mathematical model of proportional valve and simulation as performed in program Matlab Simulink. In the last part is compared the simulation of the mathematical model with the measurement on the experimental system.338 - Katedra hydromechaniky a hydraulických zařízenívýborn

Simulation of an interlocking hydraulic direct-drive system for a biped walking robot

Biped robots with serial links driven by an electric motor experience problems because the motor and transmission are installed in each joint, causing the legs to become very heavy. Previous solutions involved robots using servo valves, a type of highly responsive proportional valve. However, high supply pressure is necessary to realize high responsiveness and the resulting energy losses are large. To address this problem, we proposed a hydraulic direct-drive system in which the pump controls the cylinder meter-in flow, while a proportional valve controls the meter-out flow. Furthermore, our hydraulic interlocking drive system connects two hydraulic direct-drive systems for biped humanoid robots and concentrates the pump output on one side cylinder. The meter-in flow rate of the other side cylinder is controlled by the meter-out flow rate of the cylinder on which the pump is concentrated. A comparison of the walking simulation performance with that of the conventional independent system shows that our proposed system reduces the motor output power by 24.3%. These results prove the feasibility of constructing a two-legged robot without having to incorporate highly responsive servo valves

Fluid muscle behavior determination

Táto práca sa zaoberá zistením základných charakteristík pneumatického umelého svalu PAM (Pneumatic artificial muscle) firmy Festo, programovaním knižnice prvkov v prostredí LabVIEW pre proporcionálne ovládanie ventilu, návrhom a zostrojením stanice pre meranie.This thesis deals with the identification of basic characteristics of the PAM (Pneumatic artificial muscle) by Festo company, component library programming in the LabVIEW environment for the proportional valve control; the design and realization of the measuring station.

Automation of Universal Testing machine using Human Machine Interface (HMI)

In the material strength test, stress and strain rate are often required to be constant. For example, during the cement quality inspection, the loading rate is required to be2.4 ± 0.2KN/S [1]; when measuring the upper and lower yielding points of metallic materials, the stain rate should stay between 0.00025/S and 0.0025/S; In the determination of elongation at break, the stress rate should stay in the range of 1-10N/mm2 S-1 when the elasticity modulus smaller than 150000 N/mm2 [2]. Since 1950s, Material Testing Machines, which adopted large-flow electro-hydraulic servo, valve to form control system, have appeared in developed countries. Control system of this type could meet the requirements for the stress and strain rate in the material strength test. For example, MTS and Instron from USA, Schench from German, and Shimadzu from Japan all adopted this type of system. With the improvement of the manufacturing level of proportional valve and the development of control technology, electro-hydraulic proportional valve began to be used as the main control part home and abroad [4]. However, this type of parts, which is vulnerable to pollution, requires medium of high cleanliness. It is of large noise and high price. This type of system could go wrong easily for the complex hydraulic system DOI: 10.17762/ijritcc2321-8169.15017