MEE10:07
A TEST SYSTEM FOR THE
TELEMANIPULATOR IN
THE OPEN ELECTRONICS
LABARATORY AT BTH
Sai Krishna Dinesh Vinjarapu
Vishal Kondabathini
This thesis is presented as part of Degree of Master of Science in Electrical Engineering
Blekinge Institute of Technology
February 2010
Blekinge Institute of Technology School of Engineering
Department of Applied Signal Processing Supervisor: Ingvar Gustavsson
Abstract:
Online laboratories have introduced a new phase in the advancement of the science education systems. This aid provides more experimental opportunities for students independent of distance and time. This aid is a solution to overcome the constraint of limited laboratory hours. The purpose of the VISIR (Virtual Instrument Systems in Reality) project is to disseminate the online lab workbenches created by the Signal Processing Department (ASB) of Blekinge Institute of Technology (BTH). BTH is using them in their own courses, where the students are encouraged to work at full time on the experiments they would like to work on. The physical breadboard has been replaced by a circuit-wiring robot, i.e. a switching relay matrix which is remotely controllable. The ASB’s goal is to create a template for a grid laboratory where the nodes of the grid are different workbenches at different far off universities.
In this thesis we have developed a test system that assures the switching relay
matrix is working under normal operating conditions. A working matrix means that all the relay switches must operate as specified and components with digital interface must work and the supply voltages are within specified limits. The results of the tests specify the operational state of each relay through which we will be able to identify which relay is not
working
.
The result of the thesis is a detailed specification of the working test system with aremote control feature. The test program can be used for testing new matrices as well as the present matrices.
Acknowledgements
Primarily we would like to thank Mr. Mikael Åsman for supporting us and encouraging us to go forward with this thesis work. Furthermore we extend our thanks to Mr. Jorgen Nordberg who had confirmed the permission to go ahead with our thesis. We would like to thank the Department of Signal Processing who led us commence this thesis and to do the necessary research work and use the departmental data and the equipment.
We are deeply indebted to our supervisor Mr. Ingvar Gustavsson a Lecturer from the Division of Engineering Sciences, Dept of Electrical Engineering at Blekinge Institute of Technology. His help, stimulating suggestions and encouragement helped us in completing this thesis.
We would like to thank Mr. Kristian Nilsson a Research Student and Mr. Johan Zackrisson Research Engineer from Division of Engineering Sciences (ING), Dept of Electrical Engineering at Blekinge Institute of Technology for their support, interest, valuable hints and for all their assistance. We would like to express our gratitude towards all those who supported us and gave us the possibility to complete this thesis.
Index
Abstract
1. Introduction
2. Survey of remote Access methods
2.1 Extending VNC for extending collaboration.
2.2 A Streaming based approach for remote interaction of the multi channel display system for group users.
2.3 Development of measurement system with remote access based on internet. 2.4 FPGA E-Lab, A Technique to remote access a laboratory to design and test. 2.5 Computational Frame work for remotely operable laboratories.
2.6 Analyzing the survey for a suitable solution for remote access 2.6.1Explanation in brief:
2.6.2Software Architecture: 3. Theory of Operation
3.1Test principles
3.1.1 Relay tests using the DMM measuring resistance 3.1.2 Relay tests using the DMM measuring current 3.1.3 Relay tests using the DMM measuring voltage 3.1.4 Relay tests of the Digital Potentiometer
3.1.5 Relay tests, tests of power lines and I2C signals using the DMM or the oscilloscope measuring voltage
3.2 Test program
3.2.1 The Create Circuit module 3.2.2 The Test Item module 3.2.3 The Evaluate module 4. Conclusion
5. Reference
1. Introduction:
Online laboratories have led a new phase in the advancement of the technical education systems. This aid makes the time spent on the experiments and laboratories in an organized way and strain less to the students who like to learn things and work more on the experiments irrespective to the distance where the laboratory is situated [1]. VISIR (Virtual Instrument Systems in Reality) founded by the Signal Processing Department (ASB) of Blekinge Institute of Technology (BTH) at the end of 2006 was to disseminate the online lab workbenches and is using them now in their own courses, where the students are encouraged to work at full time on the experiments they would like to work on. The ASB’s goal is to create a template for a grid laboratory where the nodes of the grid are different workbenches at different far off universities.
The concept of VISIR is to add a remote operational option to the traditional instructional laboratories to make them more flexible to access ignoring the position or place of the user or a student weather they are in or out of the laboratory. The user can access or operate the equipment found in a local laboratory from any corner of the world using the internet. Most of the instruments in an electronic laboratory have remote control option but not for a solder less breadboard. So we need a circuit wiring manipulator which can be controlled remotely.
A relay switching matrix can serve as circuit wiring manipulator which is a part of VISIR Open laboratory. Fig.1 shows an online workbench of a relay switching matrix at BTH and copies of the same workbench are online at three different universities abroad. The desktop instruments are replaced by PXI instruments. PXI (PCI eXtensions for Instrumentation) is an international standard for instrumentation. The chassis which holds the instruments in the Fig.1 are manufactured by National Instruments. PXI instruments are PC controlled by using soft front panels of NI LabVIEW. A relay switching matrix is a device where the relays are arranged in a three dimensional pattern together with instrument connectors and component sockets. Practically a relay switching matrix in a card stack which is on top of the PXI chassis as shown in the fig.1.This matrix is designed at BTH.
When a matrix is designed and manufactured it must be tested that it works. In this thesis work of ours we are making a theoretical study of the present switching matrix checking its working under normal conditions, developing a template for a test system for a relay switching matrix which helps to open a workbench to remotely access a circuit wiring manipulator. A simple test system which can be controlled remotely have been designed and a prototype is generated. Block diagram of a test configuration is shown in fig.2. In which the prototypes of the test system are highlighted in black.
Fig.2 Block diagram of the process overview of our thesis work
2. Survey of Remote Access Methods:
Our approach for the task mentioned is to make a survey on some previous implemented and proposed schemes which make us an ease to grab some important points to guide us in our project regarding remote access to the lab.
After referring many standard journals, textbooks on the concept of remote control operation of a laboratory, we found few concepts which can be used in our work. They are mentioned below as follows:
2.1 Extending VNC for extending collaboration.
This paper states that VNC (Virtual Network Computing) is a remote access software using RFB (Remote frame buffer protocol). Here VNC is used for effective real time collaboration through internet. Three kinds of access authorities were stated in this paper. They are Administrator, the one who controls access authorities of the users. Workers are those who can access the remote resources provided by the collaboration server while the spectators can monitor the remote desktop of the collaboration server [2].
2.2 A Streaming based approach for remote interaction of the multi channel display system for group users.
This paper states that a multi channel display is used by a group of collected users. A scheme proposed in the paper states that one remote interaction system will allow a group of users to simultaneously access the multi channel display on common pc, which can achieve real time performance under main stream network environment. In this system the multi channel video generated on the server side is captured by synchronizing a group of capturing processes. A hierarchical sub tile based approach is designed to represent and compress the multi channel video using MPEG2 was designed for achieving real time performance. To control the mutli-channel application on the user side the authors re factored the architecture of VNC software [3].
2.3 Development of measurement system with remote access based on internet.
In this paper the authors described the development of distributed web based measurement system accompanied by suitable instrumentation at improved speed and scalability and portability across different platforms [4].
2.4 FPGA E-Lab, A Technique to remote access a laboratory to design and test.
main aim was to provide a student to do any experiment with in sufficient time and beyond lab hours remotely [5].
2.5 Computational Frame work for remotely operable laboratories.
In this paper authors propose a computational frame work which uses LabVIEW and web technologies to control a laboratory experiment through internet. Here they used a windows based PC which acquires images from a high speed camera for video and a proxy server which controls access of the local network. They developed software to control and acquiring data using VI in LabVIEW. Here proxy server employs a user based authentication protocol to provide security to access an experiment. In this the proxy server implements single controller multi observer architecture which helps many users to simultaneously observe and download measurements, while a single controller controls the experiment [6].
2.6 Analyzing the survey for a suitable solution for remote access
After completion of our detailed survey about considering a suitable concept for remote control operation, we found the article “Computational Frame work for remotely operable laboratories” is best suitable for our project with regard to its approach to the parameters like Vulnerability, Security, Strengths, Weakness and Ease of use.
2.6.1Explanation in brief:
Developments in web technologies help to form a network of laboratories that can be controlled and observed via internet from anywhere in the world. The frame work used here has two key components firstly, a local network with computers which acquire data using LabVIEW VI applications and secondly, a proxy server that controls access to the local network. A user can access an experiment at a scheduled time slot booked by the student or the user himself. The proxy server uses the schedule along with an authentication protocol to control the access to the LabVIEW computers. This setup needs a high speed internet connection and a LabVIEW runtime engine.
2.6.2Software Architecture:
Fig.3 Software Architecture.
For implementing multiple user access to observe the experiment, the scheme uses LabVIEW’s data socket technology which is specifically aimed at distributing measurements to geographically distributed users. Data acquisition using data sockets consists of two types of applications. One for the PXI which gathers data and publishes to LabVIEW data socket server and the other is used by remote users for observing the measurements. The proxy server controls access to the network ports using pearl based CGI scripts with in a web server to provide security to the experiment. A block diagram of the data acquisition is as shown in the figure 4.
Fig.4 Components for Data acquisition.
connects to the proxy server and request access to control or monitor the experiment. CGI script on the web server checks if the user is scheduled and then the script sets a port forwarding on the proxy server so that the user can access the experiment. The user should download a LabVIEW application from the website to observe the experiment. Port forwarding is disabled when the remote user’s time slot expires.
Fig.5 Flow chart describing proxy server operation.
The flowcharts in the figure 5 and figure 6 explain how does the process carried out for remote access and how the proxy server carries out the control for user access.
3. Theory of Operation
The relay switching matrix is a stack of PCI/104 sized boards. PC/104 is a common international standard for embedded systems. This rugged and reliable stacking technology allows multiple modules to be added to a system without the burden of backplanes and card cages. Enclosing the matrix in a box is not recommended because it should be easy to swap components and reconfigure the matrix if wanted. However, it is important to protect the matrix from non-qualified persons to be altered or damaged as the digital control electronics are sensitive and expensive and must not be touched.
The matrix shown in fig7 is stacked with four boards as shown in the fig.7. One for connecting sources, one for connecting measurement instruments, one for carrying components and for connecting external circuits and the bottom board is a source board. The two instrument boards in the middle are configured for connecting a low frequency instrument such as multi-meter and for connecting high frequency instruments such as a dual channel oscilloscope. The component board on the top carries sockets where components can be installed. One component board can carry 10 components with two leads or as many components with more than two leads as can be installed in the onboard 20 pin IC socket. By adding more component boards, more components can be online. Each board has a certain number of relays controlling the interconnection between the items and the board. Two stacking connectors connect the boards and a node connector propagates nodes to every board. The nodes are denoted A-I and 0 [7].
Each board consists of two parts. The experimenter part comprises the node connector, relay switches and instrument connectors or sockets for components and the other part is the relay coils and its control circuitry. Fig.8 shows a circuit diagram of the experimenter part of a four board matrix. The circuit in the diagram can be cut into four slices in which each slice is a circuit diagram of a board. The slices are from left to right the Component board, the DMM Board, the Oscilloscope Board and the Source Board. The source board relays are denoted as S1, S2, etc; the Oscilloscope board relays are denoted as O1, O2 etc; the DMM board relays D1, D2 etc. and the Component board relays C1,C2, etc. Most of the relays such as S3 are single pole but six relays C1, C2, C3, C8, C9 and C10 are dual pole. Thus these relays have two switches denoted for example, C1(1-7) and C1 (8-14).
The configuration in Fig. 2 is used to test the matrix i.e. the PXI equipment and the PC is connected to the matrix. The DMM and the oscilloscope are connected to the DMM Board and the Oscilloscope Board respectively. The terminals of the rightmost connector in Fig.8 are connected to the sources in the following way:
1. +6v is referenced to 0.
2. +20v is referenced to COM.
3. -20v is referenced to COM.
The relays on the Component Board must be connected to the nodes in order to be tested. A special test board connecting the relays is stacked on the Component Board. The conducting strips on the test board are shown in Fig. 8. They are also connecting the potentiometer, the I2C signals, the +5 V and +12 V power lines. The test board is described in Appendix X.
3.1 Test Principles:
In this subsection the principles for the matrix testing is described. A test program written in LabVIEW is used to perform the tests. The program controls the relays, the potentiometer ratio and the PXI devices. For example, it sends messages to the matrix in order to energize or de-energize the relays. Each message is a string of relay identifications e.g. C3, C5 meaning energize the relays C3 and C5 and de-energize all other relays. If the next message still contains C3 and C5, these relays will remain energized. Thus, include the identification of a relay in a message to energize the relay and omit it to de-energize the relay. The test program will be described in sub section 3.2.
The test system must perform three types of tests:
1. Check all the relays switches in Fig.8 operate correctly i.e. can be opened or
closed as desired.
2. Check that the I2C signals are correct and that the +5 V and +12 V power
lines are within its tolerances.
The PC and the PXI equipment are assumed to be working. The strips on the printed circuit boards and the connectors of the matrix are also assumed to be ok.
3.1.1 Relay test using the DMM measuring resistance:
The DMM in resistance measuring mode can be used to test most of the relays on the DMM board except D21, all the relays on the oscilloscope board, the relays on the source board connected to node 0 except S2 and a number of relays on the component board. A typical test loop is shown in the fig. 9. The resistance is indefinite if the relay switch is open and zero if it is closed. The following test procedure is used:
Relays on DMM Board:
1. Energize D20. Now the resistance present in the circuit considered is to be
indefinite if D20 is closed and D19 is still open.
2. Energize the relays D19 and D20 on the DMM board to close the relays. Now
the resistance in the circuit loop considered is to be approximately zero if both switches are closed.
3. Energize D19 and de-energize D20, now the resistance is to be indefinite.
4. This procedure shows that the relays D20 and D19 are working properly.
5. The same principle is followed for rest of all the paired relays connected to
DMM low and DMM High which makes the test procedure easy to test all the relays on the DMM board.
Relays on Oscilloscope Board:
1. Energize the relays D20 and D18 of the DMM board and O17 of the
Oscilloscope board, now the resistance present in the circuit considered is to be indefinite if O17 is closed and O20 is still open.
2. Energize the relays O20 and O17 on the Oscilloscope board and energize the
relays D20 and D18 on the DMM board which are connected to DMM high and DMM low respectively. Now the resistance is to be approximately zero if all the relays are closed. The setup is as shown in the fig. 9.
3. Energize the relays D20 and D18 of the DMM board and O20 of the
Oscilloscope board, now the resistance is to be indefinite as the relay O17 is open.
4. This procedure shows that the relays O20 and O17 of the Oscilloscope board
are working properly.
5. The same procedure is followed for the rest of the relays on the Oscilloscope
DMM O O20 A Low High D20 D18 017 Fig. 9
Relays on the Component Board:
The relays on the Component board connected to the nodes A, 0, B, C, D and E can be tested using the DMM in resistance mode. All the relays except C1, C8 and C3 can be tested.
1. Energize the relays D17 and D2 to close, as all the relays connected in parallel
to node 0 and node C on the component board (for instance C4, C5, C7, C6, C11 and C12) are open, the resistance will be indefinite.
2. Energize the relay C4 on the component board which is directly connected to
the node 0 and node C, and close the relays D17 and D2 on the DMM board which are connected to the DMM low and DMM high. Now the resistance is to be approximately zero as all the relays are closed. The setup is shown in fig. 10.
3. Energize the relays D17 and D2 to close, de-energize the relay C4, now the
resistance will be indefinite as the relay C4 on the component board will be open. This procedure of individual testing of each relay can be followed by the relays C5, C7, C6, C11 and C12 as they all are connected in parallel and are connected to node 0 and node C.
4. Energize the relays D16 and D2 to close, as all the relays connected in parallel
to node B and node C on the component board (for instance C10(7-1), C9(7-1) and C2(7-1).) are open, the resistance will be indefinite. The setup is shown in fig. 11.
5. Energize the relay C10(7-1) on the component board which is connected to the
6. Energize the relays D16 and D2 to close, de-energize the relay C10, now the resistance will be indefinite as the relay C10 (7-1) on the component board is open. This procedure can be followed by the relays C9 (7-1) and C2 (7-1).
7. Energize the relays D14 and D4 to close, as all the relays connected in parallel
to node D and node E on the component board (for instance C10(8-14), C9(8-14) and C2(8-C9(8-14).) are open, the resistance will be indefinite. The setup is shown in fig. 11.
8. Energize the relay C10(8-14) on the component board which is connected to
node D and node E, and close the relays D14 and D4 on the DMM board which are connected to DMM high and DMM low, the resistance is to be approximately zero as all the relays are closed. The setup is shown in fig. 12.
9. Energize the relays D14 and D4 to close, de-energize the relay C10, now the
resistance will be indefinite as the relay C10 (8-14) on the component board is open. This procedure can be followed by the relays C9 (8-14) and C2 (8-14).
DMM D4 D14 Low D E High C10 Fig. 12 3.1.2 Relay test using the DMM Current mode:
1. As per the setup is shown in fig. 13. Energize the relays S3 on the source board,
D15 on the DMM board and D21 on the DMM board which is connected to DMM high. The source (+6 volts) connected to the relay S3 is set to constant current mode. Now the DMM shows a certain value of current as all the relays are closed.
2. De-energize the relay D21, keeping the relays S3 and D15 closed then the
DMM in current measuring mode shows a zero value as the relay D21 is open.
3. Energize the relays D21 and de-energize the relays S3 and keep the relay D15
closed then the DMM in current mode shows a zero value as the relay S3 is open.
4. This procedure tests the relays S3 and D21 while keeping the DMM in Current
3.1.3 Relay test using the DMM in Voltage measuring mode:
The relays S4, S5 and C3 can be tested using the DMM in voltage measuring mode.
1. As per the setup is shown in fig. 14. Energize the relays S4 on the source board,
C3 on the component board and close the relays D15 and S2 on the DMM board which are connected to DMM High and DMM low. Now the DMM in voltage measuring mode shows a certain voltage which is being considered at S4 i.e. +12v as all the relays are closed.
2. De-energize the relay S4 on the source board by keeping the relays C3, D15
and D2 closed then the DMM in voltage measuring mode shows zero as the relay S4 is open.
3. Now energize S4 and de-energize C3 keeping the relays D15 and D2 closed
then the DMM in voltage measuring mode shows zero and the relay C3 is open. Similarly relay S5 is tested by considering the loop S5, C3, D13 and D4.
S2 C3 DMM S4 C Low V High COM D15 D18 Fig. 14 3.1.4 Testing the Potentiometer:
The potentiometer on the component board can be tested using the relays S4 and S5 on the source board and C14 on the component board using the DMM in voltage mode. The procedure is as follows:
1. Energize the relays S4 and S5 which gives the supply voltage required for the
which is connected to a ±12volts .DMM should show an expected voltage of +6volts with respect to the tolerance as per the potentiometers settings. The setup is as shown in the fig. 15.
2. De-energizing the relay C14 will make the potentiometer loop open and the
DMM in voltage mode will show zero.
Fig. 15
3.1.5 Testing the I2C Bus and the +5V and +12V power lines:
The voltage from the I2C signals can be checked using the relay C1 and C8 on the component board and using the oscilloscope to check the voltage pulse generated from the pulses of I2C signals. The procedure is as follows:
1. Energize the relays C1 on the component board and the relays O12 and O5 of
the Oscilloscope board. Then the Oscilloscope will show a DC voltage pulse of 5 volts.
2. De-energize the relay C1 on the component board and keep the relays O12 and
O5 of the Oscilloscope closed. Then the Oscilloscope will show a 0 volt pulse. This confirms us that the relay C1 is working fine and the I2C (SDA-Serial Data) signals are also working fine.
3. Energize the relays C1 on the component board and the relays O11 and O6 of
the Oscilloscope board. Then the Oscilloscope will show a DC voltage pulse of 5 volts.
4. De-energize the relay C1 on the component board and keep the relays O12 and
O5 of the Oscilloscope closed. Then the Oscilloscope will show a 0 volt pulse.
This confirms us that the relay C1 is working fine and the I2C (SCL-Serial Clock) signals are also working fine.
5. Similarly the +5 volts and +12 volts source on the I2C buss can be tested using
3.2Test Program
The test program reads the test procedure from a spreadsheet file. An excerpt from the file is shown in table 1. Each row represents one test. A flow diagram of the main routine is shown in Fig. 20. The test program is written in LabVIEW and the main vi is shown in Fig. 21. The three subroutines (sub vi’s) are described in the subsections. All the relay loops which we are testing on the matrix are shown in a table in the Appendix A.
Relay s in t h e loo p . T h e last o n e is t o b e test ed Ext ern al sou rce o r mea su re m en t d evic e V o lt age o r cu rre n t to o u tp u t D M M Fu n ct io n Exp ect ed re su lt To ler an ce Test s an d in ter p re tat io n o f a co rre ct re su lt
D19,D20 DC R 0 1 Both switches are closed
D20 DC R Inf D19 has opened and D20 is still closed D19,D20 DC R 0 1 D19 has closed and D20 is still closed D19 DC R Inf D20 has opened and D19 is still closed D19,D20 DC R 0 1 D20 has closed and D19 is still closed D18,D20,O17,O20 DC R 0 1 Test of O17 and O20
D18,D20,O20 DC R Inf D18,D20,O17,O20 DC R 0 1 D18,D20,O17 DC R Inf D18,D20,O17,O20 DC R 0 1 D15,D18,S3,D21 0 20 DC I 20 0,1 Test of S3 and D21 D15,D18,D21 0 20 DC I 0 0,1 D15,D18,S3,D21 0 20 DC I 20 0,1 D15,D18,S3,D21 0 20 DC I 0 0,1 D15,D18,S3,D21 0 20 DC I 20 0,1 D15,D18,S2,S4,C3 1 5 DC V 5 0,1 Test of S2, S4 and C3 D15,D18,S4,C3 1 5 DC V 0 0,1 D15,D18,S2,S4,C3 1 5 DC V 5 0,1 D15,D18,S2,C3 1 5 DC V 0 0,1 D15,D18,S2,S4,C3 1 5 DC V 5 0,1 D15,D18,S2,S4 1 5 DC V 0 0,1 D15,D18,S2,S4,C3 1 5 DC V 5 0,1 P90 1,2 12;-12 DC V 5 0,1 Potentiometer test
Flowchart:
Fig 21. Block diagram of the Labview code developed
The program has a main VI called Matrixtest.vi which calls many sub VI’s. The LabVIEW code when run on the machine primarily reads the tab separated text (spread sheet) file (Testprocedure.txt) and inserts into a 2D array and later into an array subset eliminating the first row present in it which contains the labels of the column. Each row is processed at a time using a while loop and the loop runs until the array gets empty. The obtained result after processing the entire LabVIEW code is inserted into an array and finally it is written into a spread sheet file before it ends (Testresult.txt). The entire LabVIEW code can be shown as an attachment in the Appendix B.
3.2.1 The Create Circuit module
This vi reads relay numbers and a potentiometer ratio if any from the first column of the file and sends this data to the matrix. The relays listed are energized. All other relays are de-energized. The potentiometer is set to the ratio listed if any.
3.2.2 The Test Item module
Testitem.vi is the heart of this LabVIEW code. This part of the code is a bit complex; here in this VI all the operation is done taking the information from the rest of the
of the row. It reads the source voltage from the next column and sets it. In some exceptional cases the source should be read from function generator or I2Cbus. The next column in the row is read and the Multimeter is set to Volts or Amps or Ohms. Then measurement is done and result is forwarded to next subVI.
3.2.3 The Evaluate module
Once the measurement is done it is compared with the theoretical values present in the next two rows. The result (OK/ERROR) is stored in the last column of the text file and inserted into the text file. When testing the relays connected to I2C bus the result is manually checked by checking the display and a user input is taken. Its result is stored into the last column and then to the text file. Once the operation with the row is completed the relays present in the loop are opened. When all the lines in the spread sheet are completed the program exits and the result can be read from the text file saved in the particular location of the system.
4. Conclusion
5. Reference:
[1] Luis Gomes and Javier Garcia-Zubia: “Advances on remote laboratories and e-learning experiences” University of Deusto, Bilbao, Spain, 2007, ISBN 978-84-9830-077-2. [2] Tae-Ho Lee, Hong-Chang Lee, Jung-Hyun Kim, Myung-Joon Lee: “Extending VNC for
Effective Collaboration” School of Computer Engineering and Information Technology, University of Ulsan, 680 - 749 San 29, Mugeo 2-Dong , Nam-Gu, Ulsan Korea, ISBN: 978-1-4244-2319-4.
[3] Zhongding Jiang, Junyi Tao, Lei Zhang, Hai Lin, Hujun Bao: “A STREAMING-BASED APPROACH FOR REMOTE INTERACTION OF THE MULTI-CHANNEL DISPLAY SYSTEM FOR GROUP USERS” Computer Graphics Laboratory, Software School, Fudan University, China, State Key Laboratory of CAD&CG, Zhejiang University, China, ISBN: 978-1-4244-2570-9.
[4] Volodymyr Hrusha, Roman Kochan, Yuriy Kurylyak, Olexander Osolinskiy: “Development of Measurement System with Remote Access Based on Internet” Research Institute of Intelligent Computer Systems, Ternopil National Economic University, Ukraine, 46004, Ternopil, Peremoga Square, ISBN: 978-1-4244-1347-8.
[5] Reza Hashemian, Jason Riddley: “FPGA e-Lab, a Technique to Remote Access a
Laboratory to Design and Test” Northern Illinois University, ISBN: 0-7695-2849-X. [6] Prakash Kripakaran, Abhinav Gupta, Vernon C. Matzen: “Computational framework for
remotely operable laboratories” Springer London, ISSN:0177-0667(Print)1435-5663(Online).
Appendix A:
Appendix B:
