Chain test bed utilises CompactDAQ platform and LabVIEW software

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When Muc-Off set out to create the world's fastest, most durable bicycle chain lubricants - with the ultimate aim of helping Sir Bradley Wiggins to smash the one-hour world bicycle distance record - the company used a truly accurate test bed equipped with National Instruments' CompactDAQ platform and LabVIEW software.

Chain test bed utilises CompactDAQ platform and LabVIEW softwareMuc-Off has been in the cycling industry since the early 1990s, and the company prides itself on driving innovation. It says it often solves problems that other companies have not realised exist yet, and the firm believes this engineering ingenuity keeps it growing and diversifying to make a positive impact. Products are provided for all forms of cycling, from commuter to competitor; however, involvement with the world's best cyclists and cycling teams has solidified Muc-Off's position in the upper echelons of the cycling world.

Muc-Off officially partnered with Team Sky in 2014. International-level cycling is comparable to premier automotive sports like F1, in which the tiniest details matter. In a sport where seconds can separate winning and losing in a 21-day tour, cyclists must make progress wherever possible. Marginal gains mean everything, so when Muc-Off claimed it could make Team Sky's elite cyclists faster by creating the world's best lubricant, Team Sky challenged Muc-Off to prove it.

This challenge drove Muc-Off to create a test system that could accurately test and measure the performance of its lubricants on professional-grade bicycle chains. The engineers needed a way to prove that the lubricants are the best available and can make the difference between winning and losing. They therefore needed to create a system that could be adjusted in many different ways and still provide incredibly accurate test results that are repeatable time and time again.

With buy-in from Team Sky, the chemical engineers ramped up work on formulating a lubricant that could perform flawlessly while other members of the team set about developing a proving ground for it. Engineers had to create the rig in an incredibly tight timeframe to keep ahead of the chemical engineers. With respect to the chain and lubricant, Muc-Off developed a test rig that emulated the essential aspects of a bicycle. The basic rig consisted of a large sprocket at the front called a chain ring, which the crank arms and pedals attach to on an actual bike. It also included a rear cassette on the back, which is the same as the gears that connect to the rear wheel on any bike, and a chain links between these two parts. The rig was mechanically adjustable to mimic countless different bicycle size and geometry combinations. This flexibility had to be replicated in every other part of the rig as well, including the software, sensors and instrumentation, and the drive for the system.

The engineers added a dynamometer (dyno) to the test system to accurately replicate cyclist inputs to the rig and conversely obtain measurable outputs. In one of the available configurations, this rig consisted of a motor that drives the chain ring like a conventional dyno to analyse torque and speed at both input and output. Early iterations of the rig used LabJack measurement devices for data acquisition and control, but this lacked the software interface and the flexibility needed. The team needed the ability to adjust the rig to deal with different sprockets, chain types, gear ratios, power expectancies and speeds. The LabJack offering simply did not have the customisability, hardware diversity, or specialist support to do the job in the tight timeframes required.

Figure 1. Lubricant test rig

Muc-Off reached out to NI because its engineers knew of the company's status in the areas of data acquisition and control. After consultation with one of the field sales engineers at NI and a quick demo of LabVIEW Signal Express, LabVIEW software and the CompactDAQ platform, the engineers were confident that NI could deliver the flexibility and scalability needed. The software could be customised to supply the vital data needed for each individual dyno configuration and test run, and the hardware could easily be scaled to allow for extra test parameters, such as driving gear changes or measuring vibration.

The combination of NI software and hardware was incredibly easy to use. However, Muc-Off's engineers are not software engineers, they are chemical and mechanical engineers, which meant that any sort of coding needed on the project would involve a steep learning curve - and that led to natural apprehension. The engineers needed to see for themselves how easy or difficult the NI offering was and how appropriate it really was to their application. They started development in the easiest way possible with SignalExpress, which has a configuration-based environment that made it simple to complete preliminary testing and confirm NI was the way to go.

It was clear at this stage of the project that the NI software could easily be tested. The benefit of an extended evaluation period of longer than a month allowed detailed evaluation without any financial risk or investment. During this evaluation stage, the engineers realised that LabVIEW would be more beneficial than SignalExpress in the long run. The graphical and intuitive way that LabVIEW empowers users to convert logical diagrams into functional code meant the engineers could learn quickly and convert their ideas of an end product into a reality in the fastest and most simple way possible. They would also still have a huge scope to diversify, expand and customise at any point in the process.

Figure 2. Chain lube efficiency dynamometer front panel

Muc-Off's engineers not only saw the value of the software and hardware provided by NI, but also in the ecosystem and services that surrounded those products. As the engineers developed the initial iterations of the rig centred on SignalExpress, they took advantage of the training courses offered by NI to make transitioning to LabVIEW simple. In this time-critical environment, the training courses gave an invaluable head start on development, which meant that race and event deadlines, such as the Tour de France, could be met comfortably.

Figure 3. Test rig in use

Cyclists talk in cadence and rider watts, while engineers are more used to input RPM and torque. The engineers needed to communicate measurements and results to technical and non-technical people. LabVIEW provided the ability to switch to a graphical representation of the data in a form that cycling professionals can easily understand, which speeded up development time greatly. Sir Bradley Wiggins used the Shimano Dura Ace 11 speed chain for his record attempt. This required some careful riding to cope with the torque, as some sprinters are reported to put out over 2000W on training machines and, therefore, use a wider chain to deal with the power. For valuable results, the engineers needed to look behind the numbers. These high wattages are only sustained for seconds, while the Daily Telegraph reported that Sir Bradley could put out over 450W continuously for an hour or more. Published data describes the variance in chain efficiency due to lubrication, with chain losses ranging between 4.8W and9 W, until now.

These wasted watts convert to lost metres/time, and Muc-Off continually strives to reduce these losses while increasing the lubrication longevity.

The main objective of the test system is to measure efficiency for analysis and comparison. The engineers calculate the efficiency of the chain and lubrication using several Muc-Off test methodologies, each incorporating the measurement of torque and speed at different regions around the chain system. The method of load application is also critical in achieving the high-resolution results required to compare lubricant types. Choosing the scalability of the CompactDAQ platform is now paying huge dividends. The testing parameters continue to grow as the engineers strive for more application-specific accuracy, so the flexibility of the system grows with the simple addition of suitable NI modules. While originally starting with the NI 9171 single-slot chassis to measure key parameters, the engineers experienced success and decided to ramp up the investment into the test rig. They now have a fully dedicated cabinet and can continue to expand the test criteria, yet keep the equipment portable enough to display at events such as trade shows.

Figure 4. Completed cabinet

This new bespoke cabinet has helped the functionality grow from a single torque and speed measurement to multiple torque and speed transducers used concurrently by utilising the NI 9201. The NI 9263 analogue output module controls speed and load, with control of other aspects of the application handled by a NI 9482 relay module. This is all housed in a four-slot NI 9174 chassis.

Muc-Off's engineers have proved that the test system is part of the winning formula, quite literally. They used the rig to test and optimise the chain that Sir Bradley Wiggins used to break the one-hour bicycle distance record. The numbers speak for themselves. In terms of results, Bradley now has another world record to his name. From official Union Cycliste Internationale data, it can be seen that in terms of distance, Muc-Off's engineers helped Bradley go three percent farther than any other man has ever cycled before in the space of 60 minutes. In terms of technology, Muc-Off created a lubricant that does not have a drop-off in performance over this timeframe, meaning friction remains consistently minimal. According to Muc-Off, no other bicycle lubricant has done this successfully before, saying that throughout the whole journey NI, LabVIEW and Compact DAQ were key to proving that.

Ultimately, the aim is always to create ever more realistic testing in the laboratory, which will require even more diverse support from NI. Muc-Off's engineers now work with NI frequently to help drive further marginal gains in professional cycling, while always aiming to bring the best of this technology to the everyday cyclist. So whether it is in-depth sound and vibration analysis or reproducing climate conditions, NI has the breadth of experience across many industries to assist in specifying and utilising the hardware and software to achieve Muc-Off's upcoming goals.

More information

Follow the links to find out more about LabVIEW products, CompactDAQ products and to see how NI products can be used in other data acquisition applications.

27 November 2015

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