Remote Access Hardware Laboratories: Are these useful and why not just use simulation?

In the wake of the recent devastation in nearby Puerto Rico which disabled travel about the region and with the incoming deluge of IoT device usage, this article seeks to explore the relevance of “remote access”, sometimes known as “virtual”, hardware laboratories for use in EE and ECE engineering courses. EE and ECE courses are uniquely positioned to make use of remote access labs because the signals being viewed ie: electrical signals, are already abstracted and mediated to the user via the oscilloscope. You are not controlling a tank of water or a mechanical device you can touch, but are only ever viewing signals on an oscilloscope screen even when seated in front of and in contact with the equipment.

Firstly, let us quickly define what is meant by “remote access” hardware labs. We are referring to a traditional hands-on “knobs & switches & connections” laboratory equipment which can be fully controlled and utilised remotely. By “remotely” is meant via a browser-based control panel GUI with the actual physical equipment communicating to the browser via a LAN or WAN. The access can either be local ie; in the same lab, or at a very large distance ie: international via the internet.

The key issue is the relative learning benefit of this methodology. Let us consider that there are 3 modes of delivery for a laboratory component of an ECE course. The first is “hardware”: the student sitting in contact with and in front of the real hardware experiment in the lab. The second is “simulation”: the student controls a program which mathematically simulates the signal processing of the circuits in the experiment. No experiment equipment involved at all. Thirdly is control of the experiment via a distance, BUT still controlling real circuits and viewing real signals; not simulations.

Most people agree that using real hands-on hardware is the superior methodology because the direct interaction between student and equipment yields the uniquely-human learning experience as the student explores the experiment through trial and error. The knowledge the student has that they are controlling the experiment parameters reinforces the learning experience: “learning by doing”.

Simulation of course is a magnificent compromise. Some would say superior to even hands-on hardware but perhaps a fairer assessment is that it is an excellent complement to hands-on hardware (ie: pre-lab learning via simulation the night before a lab session has been shown in studies to result in superior learning outcomes in students.) The implementation of electrical signals onscreen via the magic of digital signal processing enables students to explore concepts anywhere and anytime. However the beginning student may or may not realise that the digital implementation of signal processing is vastly different than the trigonometric multiplication and addition of sinusoids in continuous time which is actually what really happens in the real world. But, the convenience of simply clicking until a result which appears correct shows up conveniently masks this difference between the digital and the analog.

Professors in the field we have met often state that beginning students tend to treat simulators like video games, clicking furiously until they achieve a result without the understanding behind the result in many cases. And if the result is unexpected, they seek to blame the software itself.
What is the real “learning” in a laboratory component of a course ? The knowledge held by the introductory user that they are actually in control of the “real world experiment” and that unexpected aspects of signals can occur and can be viewed such as saturation, offsets, distortions, imperfections, etc. Working with real signals allows the students to (i) prove to themselves that theory they’ve been “taught” correlates with real world behaviour and (ii) that the real world includes effects which are unexpected, go beyond introductory theory and need to be explained and resolved.

So with this in mind, the idea of the third methodology, the compromise of studying the real signals from a real experiment, albeit at a distance, becomes a reasonable proposition.

In effect, a wide range of components and equipment can be connected and explored via multiplexed oscilloscope channels and crosspoint switches. Not as many as in a typical simulation package, however enough to give the students an opportunity to reinforce their understanding.

However, in order for this approach to be practical and economical, it needs to cater to multiple students at the same time otherwise you are simply replicating a costly hardware lab at a distance. The beauty of the signals in ECE captured on an oscilloscope is that once the equipment settings have been adjusted and the signal has been captured ie: by a single shot mode on the oscilloscope, the remote system is free to share itself with another user. It has the possibility to be in effect a “multi-user system”. Something a traditional hardware lab cannot be.

The oscilloscope only needs to consume say 5 ms of real time to capture 10 cycles of a 2kHz signal, and then 10 ms for unit overheads such as setting up the crosspoint switches, and then the unit is free to be used by another user. The unit can queue the “requests” for a signal-snapshot incoming from multiple users and deal with them in order, so multiple users are invisible to each other. The internet adds about 1 second of latency to each request and otherwise while a student muses the response to their latest interaction or writes in their lab journal, the remote unit busies itself servicing multiple other users.

From our experience with this type of equipment over the last 15 years a typical unit can service 30 -50 students at the same time independently and transparently.

So now we can think of the third methodology as a multi-user, hardware platform with no setup, no maintenance and no inventory required. Just plug it into the LAN, allocate an IP address and let students log in.

Student access can be controlled via uploaded enrolment database files ie spreadsheet files and student activity can be monitored and recorded for confirmation of utilisation levels, time of access (ie: when they all log in 15 mins before the midnight deadline they can be encouraged to get started before the deadline !) etc.

An important aspect to consider when using a remote system is that the student user must “believe” they are actually controlling the hardware unit themselves. To achieve this “confidence” a webcam can be directed to show the unit with an external oscilloscope placed alongside it so that users can view their activities resulting in the remote changes on the oscilloscope in real time. Once this “confidence” in the remote unit is established, the webcam is no longer needed.

We live in an era where we interact with spacecraft millions of miles away, albeit with a rather longer latency than 1 second, so our ability to relate to and benefit from the use of remote hardware is no longer in question. The IoT, something we’ve had since the beginning of remote industrial control panels suggests that this third alternative to hardware and software has its place in situations where distance is an issue, or cost of multiple lab stations is prohibitive, or availability of lab time scarce, so this compromise can be useful and complementary to the others.

In conclusion, the twin pillars of the laboratory, hands-on hardware & simulation software remain the main tools of preference, however the third wheel of “remote access hardware” has a place as a complement and a compromise between these two pillars. As Benjamin Franklin famously said “Tell me and I forget. Teach me and I remember. Involve me and I learn”.

P.S. This article is published in the ECEDHA News letter (Electrical & Computer Engineering Deans Association). To read the original article, please click here

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