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A customised test and measurement system will be too expensive - right?

03 August 2017

Well as with most things the answer is that it depends. Presented with something to measure or test, most of us will reach for a piece of equipment that is made to be useful in many different applications. It might be a micrometer, a multimeter or an oscilloscope.

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This is fine if we only have one thing to measure, and we know how to set up the equipment to perform the measurement that we want.

But what if we want to make the same measurement on 1,000’s of items during production? Or to measure the same thing over a few months continuously? 

Can your test engineer do that reliably? Do you need several people, perhaps working shifts, or several sets of expensive equipment? Can you make that set-up reliable and repeatable? 

All of us use electronics every day – your phone is the most obvious example, but just look at the number of other things that you use that have some electronics hardware and most probably software as well.  

But how can you use that sort of technology to make your test and measurement problems go away?

During my years selling programmable electronics hardware to customers in many industries around the world, I encountered different applications for them. It was great fun finding out how customers they were using our products. Many of these systems were inspection or measurement systems. 

A system, used special lighting and video cameras to detect cracks and bubbles in glass bottles
A system, used special lighting and video cameras to detect cracks and bubbles in glass bottles

One of the most complex systems was put together to test Bluetooth equipment. The hardware combined several DSP processors, FPGAs and analogue inputs and outputs and was fitted into an industrial PC. Our customer programmed it to test devices against all parts of the Bluetooth specification. The tests would run for more than 24 hours, trying out all of the error cases as well to see how the device under test (DUT) responded and recovered. This isn’t something that you want to be doing manually! This system was so good that it was adopted by the SIG and specified to be used at test houses that performed certification testing.

Another impressive, but simpler system, used special lighting and video cameras to detect cracks and bubbles in glass bottles. (Who knew that perfume bottles had to be as high quality as medical glass vessels? – this system was used on both.)  The really skilful part was the way that our customer lit the objects and aimed the cameras, so that the faults reflected bright spots in the image. Our hardware then searched the images for bright spots and counted pixels to measure the faults and detect their size and type. The systems could image and accept or reject 90 objects per minute – Try doing that manually! 

Not all of the projects that I came across required our expensive electronics and I was prepared to tell them that. But I couldn’t help them if they didn’t need to buy our products. These days there are lots of programmable hardware modules, boards etc on offer – even some of the chip manufacturer’s “evaluation” boards can be quite powerful. But the availability of low cost hardware doesn’t make it any easier to connect them to your systems or to work out how to programme them.

An independent Electronics Engineer can help you to define your needs, and to decide if any of the available standard options can be programmed to solve your issue. 

Very often these off the shelf boards have almost everything that you need, but not quite. For example, in our latest project we are using a Compute on Module (CoM) processor board, that allows us to easily run a Linux operating system, and communicate with a company server (and from there to the Internet) using Ethernet. But the system needs to connect to the customer’s products, and needs to run for months at a time unattended. So, we are designing some custom hardware that monitors the COM module and re-boots it if necessary and also provides the electronics to connect directly to the customer’s products. 

This custom hardware is simpler and lower cost, because the COM module is used. The COM module is low cost because it is general purpose and produced in high volumes.

The custom design enables us to use a power supply that is bought in for a few hundred pounds to replace computer controlled bench top power supplies that would have cost about £6,000 – almost paying for the custom development. 

The system that we are producing will make repeatable measurements during testing that runs overnight and during the weekends and holidays – without needing someone to be present. If a problem occurs the system will notify staff using either SMS or e-mail.

After the initial development, the customer will be able to add more test stations to the system very cheaply, and we are also considering the addition of different types of test stations to use the same controller and infrastructure – making those more cost effective too.

So it can certainly work out that a custom test and measurement system can save you money and perform a better job than struggling to use standard equipment.

This combination of custom hardware, off the shelf standard products and an Electronics Engineer to programme the system is very powerful. There can be no misunderstanding between hardware and software engineers, and there is a single point of responsibility for your project.  

About the author:

Peter Warnes was Technical Director of HUNT ENGINEERING, and is currently combining his long industry experience with young engineering talent in Dotstar Design to offer electronics hardware and software design services.

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