SHAKE TABLE RIG LABORATORY USER GUIDE
Contents
1. 4 3 2 After a Rig Session If you have completed a rig session previously and saved data you are able to retrieve the saved files by clicking the Data Files heading on the UTS Remote Labs website S REMOIEJCABS Data Files a Rig Selection 0 A list of previously saved data files should appear to download amp save the file to your computer click the text file title e g 20110812 163753 txt NS Rig Administration Rig Selection Existing Reservations Reports Data File You have chosen to open 20110812 163753 txt which is Text Document Data Files from http remotelabs eng uts edu au What should Firefox do with this o After clicking the text file title a browser specific download window should appear be sure to click Save File or similar in this window to save the file in an appropriate location on your computer Labshare 2011 Page 11 Version 2 0 Shake Table Rig Laboratory User Guide lab share 5 FAQ amp Troubleshooting 5 1 Contacting Support Any questions regarding the nature of assessment tasks should initially be directed to the relevant academic If the user encounters any difficulties during the course of using the rigs the Contact Support button should be used to request assistance and report an incident The following popup will appear please enter your name and a valid email address followed by a category from the T2. The damping level applied to the level 1 damper is indicated by a blue line with the level 2 damper indicated by a pink line Labshare 2011 Page 8 Version 2 0 Shake Table Rig Laboratory User Guide lab share 3 6 Fast Fourier Transform FFT Generation A real time Fast Fourier Transform FFT can be performed on the displacement data This can assist in finding the resonant modes or in performing various other frequency based analysis techniques on the system Be sure to click the FFT tab to generate the FFT on the displacement data Displacements FFT Lissajous Level O Level 1 Level VV 24 a Le 2 x 1 25 15 1 75 2 225 25 2 75 3 3 25 35 3 75 4 425 45 4 75 5 Frequency Hz The FFT is a plot of the amplitude on the left hand scale axis against the frequency Hz along the horizontal axis The figure above shows the FFT generated on the first few seconds of data at an excitation frequency of 1 75 Hz The FFT performed on the base level 0 data is indicated by the white line level 1 by the red line and level 2 by the green line 3 7 Lissajous Curve Generation A real time Lissajous curve can be generated based on the displacement data This allows you to determine the phase relationship of the various levels Be sure to click the Lissajous tab to generate the curve Displacements FFT Lissajous Cv Coil 2 Temp 0 L1 mm The selection of Level X versus Level Y can b
3. 2011 Page 5 Shake Table Rig Laboratory User Guide lab share Version 2 0 2 1 Controlling a Rig If the rig is free you will be immediately taken to the rig page where you can access the Shake Table rig control software To run the control software click the launch button VMS Remote Laka Shake T asia 1 Moda firetoe 209 t Yew Mapag look a PE 4 Rig Control gs REMOTELABS Shake Table 1 bd 00 2 29 40 174 Launch PEG images 3 Rig Control Software After clicking the launch button you should be presented with the rig control software This is a LabVIEW application that allows you to control the motor and eddy current dampers as well as observe the displacement frequency and phase of the base and each level labYshore Shake Table 1 2011 1 Temp CC Displacements FFT Lissajous Coil 2 Link Enable Motor Autoecale Iv Level 0 Level 1 Level 2 Enable Damping 96 Frequency 100 z Level 1 Damper Displacement mm Buidweg Damping 100 50 1395 90 1406 13 Time s Se MB Loggedin Me LL Export FFT Figure 2 Rig Control Software with the system being excited by a motor frequency of 1 75 Hz Labshare 2011 Page 6 Version 2 0 Shake Table Rig Laboratory User Guide lab share 3 1 Rig Status Upon launching the rig control software f
4. already selected Remote Labs Rig Setection ca gs REMOTELABS a Rig Selection Beee id Coupled Tanks FPGA Loaded Beam OMAP PLC Shake Table Rig Types nus Now you can either select a specific rig to control or select from any of the available rigs It is suggested to select from any of the available rigs Click the Shake Table icon to make this selection ns Qi UTS Remote Labs Pig Selection Mosa Firefox a L dt Matery beceran Jocis Rig Types i Te rernetalabs eng us edu sul queue 4 75 REMOTELABS F Legend Rig Selection D ouo FE RTE SIC gt 2 BEBE ee eee gt m Shake Table pu Mb pi 2 1 Queuing for a Rig Once you ve made your selection you need to queue for the rig After this step when the rig is available you will enter a session whereby you are able to control the rig Click the queue button or alternatively click reserve if you wish to schedule a session for future use See Labshare s Generic Rig Access Guide for more information on reserving a rig GUTS Remote Labs Fig Selection Mozilla Firefox ol gt mS fie fdt Bookmarks loch Pc e Shake Table umm 175 LABS 8 Legend Rig Selection 4 Free p a 2 O nu 1 Shake Table 2 cm gt Shake Table3 Shake Table 4 nuanuuua 3 Wan Cancel Reserve Queue Labshare
5. core is attached to the object requiring position measurement and this moves along the axis of the tube An alternating current is driven through the primary centre solenoid coil which mutually induces a voltage in the secondary coils As the ferromagnetic core moves the induced voltages change and the position can be measured by measuring the difference between i e the differential the two secondary coil voltages 1 2 4 Eddy Current Coil Damping A copper plate is fixed to each level of the building model extending between a pair of coils which when turned on generate a magnetic field that permeates through the copper Motion in each storey of the model causes the copper to move at a given velocity relative to the coils which generate eddy currents within the copper itself These eddy currents in turn create a magnetic field of their own resulting in a damping force that opposes the motion of the copper hence suppressing vibration for that level Note that the current in each coil is supplied by an amplifier and the temperature of each coil measured using a temperature diode If the temperature rises above 85 C the system automatically turns off the coils to prevent damage to the equipment The rig will not be operable until the temperature falls below this threshold 1 2 5 Data Acquisition and Feedback Data acquisition and control is implemented using a LabJack UE9 device and National Instruments cRIO These are linked to the rig
6. e toggled via the plot drop down menu at the top right of the curve plot The phase relationship can be determined by the curve shape Labshare 2011 Page 9 Version 2 0 Shake Table Rig Laboratory User Guide lab share 4 Rig Data Acquisition Users are able to save sensor data for displacement coil damping as well as the generated Fast Fourier Transform FFT TECHNOLOGY SYDNEY lab shore Shake Table 1 Displacements FFT Lissajous Autoscale 80 4 1 Saving Displacement amp Coil Damping Data Displacement data can be saved whilst your session and the rig control software is active by clicking the Start Save button Data will be recorded and saved to a tab delimited text txt file at 0 01 second intervals The data is divided up into columns with the column order being Time s Level 0 Displacement mm Level 1 Displacement mm Level 2 Displacement mm Level 1 Coil Output Level 2 Coil Output When you have completed your experiment or recorded the appropriate data be sure to click the Stop Save button 4 2 Exporting Fast Fourier Transform FFT Data Real time Fast Fourier Transform FFT data can be saved whilst your session and the rig control software is active by clicking the Export FFT button Data will be recorded and saved to a tab delimited text txt file The data is divided up into columns with the column order being Frequency Hz Level 0 Amplitude Level 1 Amp
7. lahare SHAKE TABLE RIG LABORATORY USER GUIDE VERSION 2 0 Labshare 2011 Version 2 0 Shake Table Rig Laboratory User Guide lab share Table of Contents PNE E m ED A aa 2 1 4 Remote Laboratories 2 ETT OO T IET 2 1 2 Shake Table The Rig Apparatus iii 3 WCB ASC 3 12 2 DEPA Enr o N O a 4 1 2 3 Linear Variable Differential Transformer 4 L24 ECC Current kaa TET m 4 1 25 Data AGquisition and Feedback iiis 4 2o e1 o 5 2 1 SIS II AIO en T E de BAR Aa een T ee 5 2 1 QU TE ci 6 MEME ER TS KENAN E RE ER NE EE RES EEE 5 2 1 GONI SINING A RIO PNE TET NAGA AKA aa RU RE PE gan a baba aka bab a 6 2 PO COR O SON edi a naa a eaaa a a aaa ga iane hc ge aaa Phan mec 6 3 1 DUC RS UE UE MT 7 3 2 WeregSo ee aaa naa ee 7 3 3 Eddy Current Damping Control sise 7 3 4 Linking Enable States for Motor amp Damping Control 8 3 5 Displacement amp Damping Measurement enne nnne nnne nnne nnn nnns 8 3 6 Fast Fourier Transform FFT Generation sise 9 Sel Lissajous Curve Generation ccccccccsssseccecceeeeeeeeecaeeeeeeeeseeueeeeceeesceeessesseceeessaueceessseaseeessssageeeeeeaa
8. litude Level 2 Amplitude Since the FFT data is purely real time acquisition i e a snapshot there are no other buttons to press consequently no need to stop saving the data Labshare 2011 Page 10 Version 2 0 Shake Table Rig Laboratory User Guide lab share 4 3 Downloading Saved Data As noted any saved exported data is saved to a tab delimited text txt file This these file s can be retrieved either whilst in a rig session or after the rig session has concluded Please follow the processes outlined below for each scenario 4 3 1 During a Rig Session If you wish to download your data during a rig session go to the UTS Remote Labs website window you used to launch the rig control software On this page there will be a Session Files heading with a list of all saved text files Click the text file title e g 20110812 163753 1 1 to download amp save the file to your computer 375 REMOTELABS 25 You have chosen to open 7 20110812 1637534 Shake Table 1 which is Text Document from http remotelabs eng uts edu au 00 27 42 What should Firefox do with this file C Qpen with Notepad default iv Save File a a a VLC Media O p a a Lo After clicking the text file title a browser specific download window should appear be sure to click Save File or similar in this window to save the file in an appropriate location on your computer
9. nable Level 1 amp Level 2 Damper Enable Auto Disabled Red User Disabled Red e g If the Link Enable button is enabled and the user enables the motor the damping will automatically be disabled In enabling the Link Enable button the user can be sure that damping will consistently be applied repeatable time delay when the motor is disabled As a result damping times can be compared and sources of error variation removed from any damping related experiments 3 5 Displacement amp Damping Measurement The majority of the control software is taken up by the various measurement graphs The Displacements graph is shown by default The displacement graph displays displacement sensor data for a 10 second interval from the present time right hand side to present time 10 seconds left hand side Displacements FFT Lissajous Coil 1 Temp Autoscale Level0 Level1 Level 2 79 AR A AZ KAN AIAN AA AJ AA Buidweg c a a gt a w m Time 5 The left hand scale axis is used for displacement and by default measures from 80mm to 80mm An Autoscale tick box has been added to allow for more precise measurements at small displacements The base displacement level 0 is indicated by the white line Level 1 is indicated by a red line and level 2 by a green line The right hand scale axis is used for damping and by default measures from 0 to 100
10. or the first time during the session two green indicators in the bottom left hand corner will light up to inform the user that the current system is now connected to the hardware server and initialised Connected and Logged In lahare Shake Table 1 Displacements FFT Lissajous Connected Logged In The status bar underneath will read Resetting system as the coils are turned on to provide full damping for a couple of seconds to ensure that any vibrations are removed from the system before operation Once initialisation is completed the status bar will change to System Ready and the controls for the coils and motor will become accessible 3 2 Motor Control The motor frequency can be controlled by the slider on the right hand side of the rig control software The frequency can be adjusted from 0 Hz stopped no rotation to 8 Hz in intervals of 0 01 Hz The motor has been calibrated for this frequency range The frequency can be adjusted either by dragging the yellow slider marker up and down with your mouse cursor by typing the desired frequency in the motor frequency input field or by clicking the and frequency adjustment buttons which will increase and decrease the motor frequency by 1 Hz respectively Be sure to click the enable toggle button to put the motor in the enabled state green at the motor at the frequency you have set The motor can be stopped by either toggling the but
11. ratory experience remote laboratories can provide significant benefits Indeed multiple research studies have demonstrated that whilst there are some learning outcomes that are achieved more effectively through hands on experimentation e g identification of assumptions specific haptic skills there are other learning outcomes that are achieved more effectively through remotely accessed laboratories e g processing of data understanding of concepts Engineering students are able to access the Shake Table rigs to help them develop and verify their mathematical models of the complex system dynamics The Shake Table allows students to Characterise the behaviour of a 2 degree of freedom system Acquire experimental data to assist in developing a simplified model of the system Analyse the system response across a range of frequencies by measuring displacement performing a Fast Fourier Transform FFT on the data in real time or generating Lissajous curves for each level in real time Labshare 2011 Page 2 Shake Table Rig Laboratory User Guide lab share Version 2 0 1 2 Shake Table The Rig Apparatus The Shake Table Laboratory was designed to model the behaviour of a building during an earthquake scenario It is hosted by UTS and helps students break down and understand the complex dynamics of such a system Five rigs were developed as two storey structures that emulate vibrations in a single direction with 2 degrees of f
12. reedom Two extra rigs were also developed with three stories to model movement with 3 degrees of freedom Each Shake Table rig consists of the following main components building model Where each level has a known mass Connected by a material with a known stiffness coefficient Displacement sensors for each level of the building base plus a motor to provide appropriate excitation Damping coils with a known damping coefficient Data acquisition and control hardware A web camera for visual feedback Acontrol interface written in LabVIEW PEE S mil SU 2 Displacement e c f AN Sensors 05677 Eddy Current e T3 Coil Dampers a ST 1 i Electric Motor e c E LE J e Guide Rail eee Scotch Yoke Mechanism ax Figure 1 2 Degrees of Freedom Shake Table with base displacement measurement LVDT 1 2 1 The Base The model itself sits on the Shake Table platform where the base level i e level 0 glides along a low friction guide rail Rotational motion from an electric motor is converted into linear motion via a scotch yoke mechanism providing base excitation at a user specified frequency Changing this frequency allows the user to model different earthquake vibration conditions The base amplitude of displacement during an earthquake is modelled by setting the stroke on
13. s 9 ACO WISIIOM PR I ang aa aaa aka E a aa I aaa I aa naa a sia apake 10 4 1 Saving Displacement amp Coil Damping Data 10 4 2 Exporting Fast Fourier Transform FFT Data 10 4 3 Downloading Saved Dala uuu abaan anana a na gag ak UN a AK aaa d aa aa Kg an b anga a aa KA Gd agan ak a a pa aga aga b Akan 11 4 3 1 During a Rig Session cccccccccssssececcceeeseeeeccaessecececseusececsseuaseceessuaaeeecsseaaeeeeessuaseeessseageeeessagagss 11 4 3 2 After a Rig Session seessssssssssssssssessee eene nnne nenne nn nnne nnns naen anana aana annes nnn nsn nnn 11 9 FAQS T OUDI SOON sas eee ee ne ee 12 5 1 E o irlen ais pelto e9 g 12 5 2 Providing Feedback AMNEM aR EE Sana a D aa Ba A aa Ka aaa Aa 12 Revision History 22 09 2009 First draf LaReine Yeoh 21 06 2010 LaReine Yeoh 14 09 2010 Internal Release Ellie Burke Labshare 2011 Page 1 Shake Table Rig Laboratory User Guide lab share Version 2 0 1 Introduction 1 1 Remote Laboratories Remote laboratories enable students to access physical laboratory apparatus through the internet providing a supplement to their studies and existing hands on experience Students carry out experiments using real equipment but with much greater flexibility since access can occur from anywhere and at any time Their interaction with
14. server PC via an Ethernet connection Software written in LabVIEW hosted on a virtual machine running Windows Server 2003 allows users to gather the data and operate a single Shake Table Rig An Apple iSight webcam gives the user visual feedback of the Shake Table in action in real time accessible via the Internet from the Remote Labs web page Remote data acquisition and feedback control on a fast moving dynamic system is a challenge over the Internet For a good control system to work both the acquisition and feedback should be done within a very small timeframe to achieve a good response In order to achieve this data is constantly being streamed from the LabJack and cRIO using a fast hardware timed acquisition rate Labshare O 2011 Page 4 Shake Table Rig Laboratory User Guide lab share 2 Session The following section outlines the procedure for utilising the Shake Table Rig Laboratory which is similar to other Remote Laboratory Rig types already in use The software that runs the Remote Laboratories and provides access to the rigs through a web browser is called Sahara For the purpose of using the rig it is assumed that users have access to a workstation that meets the system requirements Users should refer to Labshare s Generic Rig Access Guide for this information 2 1 Selecting a Rig Once you have logged in you will be directed to the Rig Selection page On this page click the Shake Table tab if it is not
15. the motor which can be adjusted manually Labshare 2011 Page 3 Shake Table Rig Laboratory User Guide lab share Version 2 0 1 2 2 Displacement Sensors The displacement of each level is measured by a contactless MTS C series Magnetostrictive Linear Position Sensor Button magnets are fixed at the back of each level which travel up and down the waveguide sensing element during vibration The effect of the external magnetic field causes the ferromagnetic material of the waveguide to change its shape at that particular point on the sensor To read the magnets position an interrogation current pulse is sent along the waveguide from the base of the sensor which generates a radial magnetic field as it travels When it reaches the point at which the button magnet is placed the two magnetic files interact with one another Then a mechanical strain pulse is emitted back towards the base of the sensor in the form of an impact soundwave which is detected and converted into a voltage signal by the sensor electronics The button magnets are attached to the center of each level with the rest position of the building structure roughly between 70 75 mm in absolute displacement 1 2 3 Linear Variable Differential Transformer LVDT The displacement of the base level 0 is measured by a Solartron Metrology DG Series Linear Variable Differential Transformer LVDT The LVDT has three solenoid coils placed within a tube A ferromagnetic
16. the remote equipment is assisted by the use of data acquisition instrumentation and cameras providing direct feedback to students for better engagement Traditional engineering laboratories require students to be physically present in order to work with equipment which may limit student flexibility Conversely remote laboratories let students work in their own time and even repeat experiments for better learning outcomes Of course students cannot actually touch and feel the equipment in a remote laboratory but they can still perform most other tasks relevant to their learning Sometimes separation from potentially hazardous equipment is preferable from a safety point of view Due to the increased use of remote operation in industry where machinery and entire plants are often controlled from a distant location students may directly benefit from learning how to remotely control equipment Furthermore remote laboratories provide the opportunity to access a wider range of experiments as costly or highly specialised equipment may not be locally available This presents the opportunity to share laboratory facilities between institutions Significant research and pilot studies have been undertaken in Australia and by several groups around the world into the educational effectiveness of using remote laboratories These studies have consistently shown that if used appropriately in a way that is cognizant of the intended educational outcomes of the labo
17. ton back to the disabled state red or by adjusting the frequency to 0 Hz 3 3 Eddy Current Damping Control In the same way that the motor frequency can be controlled the eddy current dampers can be controlled via the sliders for each level towards the middle right of the rig control software The damping for each level can be adjusted from 0 to 100 in increments of 1 This can be performed by either dragging the yellow slider marker up and down with your mouse cursor by typing in the desired damping level in the damping level input field or by clicking the and damping level adjustment buttons which will increase or decrease the damping level by 1 respectively Be sure to click the enable toggle button to put the damper in the enabled state green at the damping level you have set The damping can be removed by either toggling the button back to the disabled state red or by adjusting the damping level to 096 Labshare 2011 Page 7 Version 2 0 Shake Table Rig Laboratory User Guide lab share 3 4 Linking Enable States for Motor amp Damping Control In order to assist students with analysis of damping times a Link Enable button has been added to the control software Link Enable Level 2 Damper Motor Enable Enable This button inversely links the enable toggle buttons for the motor and damping control The button works according to the following truth table Link Enable Motor E
18. ype drop down list Remote Labs Login T dm M lose UNIVERSITY OF CD v Lx zs Login ogin Laboratory Rigs 2 Contact Support The request will be sent to the Remote Labs support team Name Email Type Help Request Purpose Feedback You may then enter a brief statement regarding the nature of the request in the Purpose field Be sure to enter as detailed a description as possible of the incident in the Feedback field 5 2 Providing Feedback Users are strongly encouraged to leave feedback and comments of their experience with the rigs to help improve the system as well as any suggestions for additional features to be included in the future For any enquires or assistance contact the Labshare helpdesk at helodesk labshare edu au Labshare 2011 Page 12
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