Sensor Systems – Getting to Market… Quickly!
By: Chris Roff
Head of Smart Sensors
1st February 2017
As an engineer, when somebody comes to see you with an exciting technical idea, you are always keen to listen. But, when the first meeting is on Halloween, and the business case requires complex prototypes deployed before Christmas you’re allowed to worry that it could be a little scary! But, with careful planning, lots of experience and a team who know what’s what, it’s possible to deliver without getting spooked.
This particular project was in the smart sensors area and required an array of about 20 different environmental sensors (some of which needed creation from scratch), a pair of backhaul radio options (cellular and ISM) as well as a secure backend interface. Security was extremely important and the device had to operate in a harsh environment. Oh – and it all had to run from a battery with tough lifetime specs and sit inside a unique custom enclosure…
We responded to this design and timescale challenge by bringing the customer’s technology leads into our offices for a week-long workshop. The week’s agenda started at high-level aims and finished with electronic schematics being sketched out – progress!
The next phase of the programme saw high-risk sensors being prototyped in the laboratory whilst the electronic schematics were being fine-tuned. Meanwhile Printed Circuit Board (PCB) layout engineers were creating component footprints and doing everything possible to be ready to route the schematic as soon as it was released. Having a good view of the components that exist in the sensor market is vital to allow rapid down-selection of appropriate devices (from the often intimidating range of options).
At the same time, software engineers were devising the message protocol for the radio communications and working on low-level drivers for the chosen components. Embedded device software suitable for battery powered sensor systems requires working with limited memory space and real pressure to control current consumption.
Another parallel effort was looking at the mechanics, designing enclosures, IP68 seals, cable assemblies and the like. Modern 3D printing and soft tooling facilities allow large complex designs to be realised within even the most aggressive schedules. And watching the machines in action is a sight to behold.
Once the electronic hardware is nearly designed in CAD, the supply chain must jump into action, securing components “kitting up” and arranging access to pick and place assembly lines. Supply chain guys are an engineer’s best friend when time is tight – they always manage to locate that rare component just when you think the lead time is unworkable.
After assembly, when the product returns from the factory, it can be a tense time. Everyone is proud to see their hard work made real, but equally tense that one mistake overlooked during design could render the boards useless. Usually there’s a deep sigh of relief when the first LEDs flash and no smoke appears!
The next stage is to bring the board up, test hardware functionalities and software control. Typically a plan for these activities is made beforehand and a burndown list is worked through to ensure nothing is missed. Ticking off working functionalities is very satisfying for engineers but the thrill is perhaps greatest for the project managers!
Inevitably along the way some modifications will be required when bits of circuitry don’t work quite as they did in the simulator or on paper. The trend for smaller and smaller electronic components means that this work requires sharp eyes and a steady hand with soldering irons or hot air guns. When you have a deadline, having technicians or “wire men” with nerves of steel on your side is invaluable. Having patient ones is a bonus too!
Once the hardware is functioning as desired and the software has been developed to beta level you can begin system tests to verify that the product will do what it needs to in the field. The key here is to plan a suite of test conditions that cover both normal operation and all likely corner cases. At this stage modifications may again be required to arrive at the stable end product.
Once the design passes test it’s ready for showtime. Final assembly, shipping and installation of prototype units before Christmas? No problem for this team! Now there’s just time to monitor that sensor data over another portion of Christmas pudding…