EPFL Creates a Flexible Remote Experimentation Environment Using Mac OS X and NI LabVIEW

Author(s):
Denis Gillet - École Polytechnique Fédérale de Lausanne
Christophe Salzmann - École Polytechnique Fédérale de Lausanne

Industry:
Education

Products:
PXI/CompactPCI, LabVIEW

The Challenge:
Providing reliable, attractive, and efficient access to 30 physical experimentation setups concurrently used by local and remote students.

The Solution:
Using National Instruments LabVIEW, a single application provided all the required services for implementing a remote experimentation server, from the access to the real equipment using the NI Measurement Hardware DDK to the data exchange with the remote application using the TCP/UPD.

The Need for Student Experimentation Resources

École Polytechnique Fédérale de Lausanne (EPFL - Switzerland) offers flexible, hands-on experimentation resources to engineering students to strengthen active learning and collaborative work. As a result, students can freely choose to carry out an experimentation module within the laboratory premises or remotely from home. Remote-control technology is key for such a deployment. For the last 10 years, the academic community has dedicated a large effort to developing remote-monitoring and control prototypes that meet educational requirements. In fact, some prototypes have been deployed and validated with actual curricula.

At EPFL, we proposed flexible, hands-on experimentation modules to complement the automatic control theory studied in the classroom. A classic lab session includes the steps typically followed by practitioners. A team is formed and defines the experiment planning. Next, the team models the physical system to be controlled. Then, the team takes real measurements to identify the physical model parameters using ad-hoc procedures. Finally, the team designs and implements a real-time controller. We assess the performances to verify that the teams followed the given specifications.

We solved many challenges to provide the students with a professional, quality environment that is available 24 hours a day, seven days a week. We found challenges in areas such as maintenance, deployment, reusability, and functionality. While educational and collaborative functionalities (reservation and allocation) are handled by the eMersion¹ environment running on an Apple Xserve, we used NI LabVIEW to develop and maintain a robust and professional-looking solution for the remote experimentation servers.

The Power Mac G4/G5 Role

The laboratory offers concurrent remote accesses to 30 physical experimentation setups. The setups include 22 electrical drives², seven process trainers, and one inverted pendulum. We connected each physical experimentation setup to a Power Mac G4/G5 computer. The computer role is three fold. First, it controls the physical setups in real time using a digital controller. We interfaced the physical setup through an NI data acquisition (DAQ) board. Secondly, the computer acts as a remote server to transmit the acquired information to the client application. This includes live video stream and digital measurements. The server also receives the user parameters to be applied to the digital controller. The computer performs this information exchange in real time, resulting in an efficient interaction between the distant user and the physical equipment. For example, less than half a second is required for the user to perceive the feedback due to a parameter change. Third, it feeds the collaborative student space with data fragments, such as controller settings or measurement samples. Students use this feature to document their work and share their results with peers. The collaborative space provides a shared laboratory journal component built as a part of the eMersion environment. The data exchange between the LabVIEW server and the collaborative space uses a single-click interaction mode that is essential for a successful tool appropriation by students.

We implemented the digital controller, remote experimentation server, and eMersion environment link using LabVIEW. Using Mac OS 9, we implemented the control algorithm using a custom-made, real-time kernel that can directly access the NI hardware (PCI-1200). Using Mac Os X, the solution is simpler. Also, using LabVIEW 7, we can take advantage of the new Mac OS X multithreading capabilities and benefits from the Power Mac G5 velocity. We used the Measurement Hardware DDK to directly access the DAQ board (PCI-6025), thus permitting a complete LabVIEW solution. We implemented the video acquisition in C and interfaced it with LabVIEW via a code interface node (CIN). The CIN provides access to any available QuickTime video inputs, such as USB or FireWire. We used the later interface to connect a Unibrain Fire-i camera.

The remote experimentation server uses the provided TCP and UDP services (VIs) to implement the client application communication. The exchanged information format is well defined using XML. Therefore, any third-party applications can interact with the LabVIEW server and eMersion environment, provided that they understand XML and are able to communicate via TCP or UDP. By directly controlling the transmission process, we can synchronize the video and acquired measurements. This direct control also permits the adaptation to the client characteristics and the available bandwidth, thus providing the user with the best possible service quality.

We designed the client application user interface as a cockpit, where all the useful information is directly visible. The user interface displays measurements in an oscilloscope graph and also displays the physical equipment video images in a picture indicator. The user can change the controller parameters using sliders. He or she can also remotely disturb the setup to assess the implemented controller robustness. We used the LabVIEW GUI elements (controls and indicators) to implement a professional-looking solution that is clear and attractive to the remote users.

The client application is meant to run on various devices and OSes. For deployment reasons, the standard client application solution runs under Java. The java applet replicates the reference LabVIEW client application. We also developed a PDA client application using the LabVIEW tools.

LabVIEW Simplifies Development

Our development and maintenance cycle was greatly simplified through the versatility of LabVIEW and its integration with the Mac OS X environment. A single application running on a Power Mac G5 provided all the required services for implementing a remote experimentation server, from the access to the real equipment using the Measurement Hardware DDK to the data exchange with the remote application using the TCP/UPD.

(1) The eMersion project: http://emersion.epfl.ch

(2) The eELab is provided by  www.schorderet-technics.ch/

For more information, contact:

Christophe Salzmann

EPFL

E-mail: christophe.salzmann@epfl.ch

Tel: +41 21 693 38 49

Fax: +41 21 693 25 74

 

 

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