NI ELVIS at work

Projects that inherently challenge students to employ innovative design thinking often involve interacting with an unknown process or device. Read more about how ELVIS was used in practical situations.

Students are encouraged to understand the unknown through theory, simulation, and experimentation; however, projects that introduce the unknown in the messy, multi-system environment it exists in naturally tend to challenge the students to be much more innovative. Designing a test in this style not only requires an understanding of specifications, the limitations of the equipment, and the fundamental concepts being applied but it also requires students to contend with outside factors and how one change can have a cascading effect on the experimental setup.

Figure 1: Topic distribution of the Fundamentals series of courses
Take, for example, the University of Virginia teaching a series of courses in electrical and computer engineering they call the Fundamentals. Fundamentals seeks to convey the fundamentals of electrical engineering including circuits, electronics, and signals and systems all in one series of courses that iteratively build on each other. So rather than teaching Operational Amplifiers as an individual topic, the students analyse the signals that go into the OpAmp and how those characteristics influence the performance of the OpAmp.
The first semester culminates in students creating a four-input summing amplifier, representing the combined knowledge of simple circuits, OpAmps, and signals to fully comprehend every element of the project. The University of Virginia, since implementing this change in course structure, has seen a 15% increase in concept inventory scores and has seen significant improvement in the innovative quality of student design projects at the end of the year.

To most effectively analyse concepts in this manner, not only do students need the ability to effectively instrument and analyse the experiment, but precise control and the ability to manipulate the type and behaviour of the inputs to the system are critical to a student’s understanding. The NI ELVIS III is the only engineering laboratory solution that combines seven traditional instruments with fully customisable I/O, enabling complete implementation of the concepts in context approach.

The development of a reliable, repeatable test challenges students to plan as a group, properly define test steps, and provide an output that communicates relevant information about test conditions, whether it passed or failed and why. These repeatable experiments require students to consider and monitor elements outside of the major focus of the test.

Take, for example, the experimental methods course at Georgia Institute of Technology. One of the important concepts taught is vibrations of a free and forced beam. In this experiment, students need to be able to monitor a force transducer, a laser doppler velocimeter, and control a shaker all while ensuring the accuracy of the amplifier and signal conditioning circuitry. While the concept being taught is singular – measuring a beam’s forced response – it requires a multi-faceted approach to developing a sound experiment which requires multiple elements to be monitored at once. Georgia Tech’s answer to this is a laboratory solution that exposes both instruments and controls and can serve as an interface to more than one student at a time. This degree of teamwork and level of sophistication in a project gives students the confidence they need to tackle harder problems after graduation.

The NI ELVIS III combines instrumentation and control specifically to service experiments and learning experiences like this one. Students have a need to create a controller which precisely shakes a beam yet the amplifier for the shaker and the signal conditioning for the force transducer needs to be stable and accurate to ensure a successful experiment. Instruments such as a 4-channel oscilloscope and a 16-channel logic analyser give students the security of knowing the results of their experiment are valid.
The Engineering Method

Figure 2: The Engineering Method
Take, for example, the third and last semester of the University of Virginia’s Fundamentals series. The final project is to build an electrocardiogram or EKG. The students use their knowledge accumulated over three semesters of electrical engineering fundamentals education to understand and apply knowledge of complex signals, data acquisition, instrumentation amplifiers, and data processing. These students really do go through the engineering method as they will need to realise that the trace length and components they select really matters to acquire a clean, intelligible signal.

After completing their designs and testing it out for the first time the students realise they have a problem: the signal is nearly completely noise and not the expected output. At this point the students are within the ‘test solution’ phase of the engineering method and need to go back to the ‘brainstorm, evaluate, and choose solution’ phase. Because the students have an exemplary understanding of signals in the context of circuits and systems, they conclude that the noise is being introduced through a combination of the power supply and the room lights. After passing that through a digitally implemented FIR filter, the students suddenly see their real heart rate and communicate the results to their professor.

By following the engineering method and having the flexibility to prototype and implement elements digitally, students realise how to resolve issues in their project and report on lessons learned.