Pimp my sensors

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Alto Performance Racing’s Vyrus 994cc bike has been modified with sensors to monitor and improve the bike’s performance during the 2008 Thunderbike UK motorcycle championship

The bike features a front swing arm suspension system with hub-centre steering and the Alto team and Towcester-based company Variohm Eurosensor supplied position, pressure and temperature sensors to measure and continuously improve the machines’ performance.

Unlike conventional motorbikes with front forks which suffer from inherent handling problems caused by deflection and stiction plus a tendency to ‘dive’ under braking, the aluminium swing arm separates the steering and damping systems to offer much improved handling as the trail and the steering angle remain constant in all conditions.

As with all levels of competitive autosports, monitoring dynamic data and interpreting results is fundamental to performance improvement. At the test track and on race days, Alto use Variohms’ sensors under extremely arduous conditions to acquire fast and precise feedback for race critical parameters that include front/ rear suspension position, front/rear brake pressure and throttle position along with tyre and ambient air temperatures, barometric pressure and engine rpm.

These real-time readings combine to pin-point information delivered from the bikes’ CANbus network by telemetry to data loggers that determine exactly how a machine and rider has responded to the intricacies of the track and provide the race team with essential statistics for continuous design and set-up improvement - and race winning performance.

The ruggedised Autosports version of the ELP series slimline linear position transducers are used for the suspension ride-height feedback during braking, cornering, track bumps and undulations. The compact sensors conductive plastic track is fully sealed to IP67 and fast replacement is assured with optional ‘pop’ mountings.  High linearity and excellent positional repeatability combine with a very wide temperature range and mechanical life in excess of 25 million operations to provide a highly reliable position feedback transducer.

The bikes’ throttle reading is measured with a Vertex 13E series, 14-bit resolution angle sensor. This highly durable and compact 13mm diameter sensor is IP69 rated and the non-contact hall effect and magnet design yields an almost limitless life. Within the Vyrus application the programmable 0 – 360 degree electrical angle is calibrated in-situ to provide highly accurate and repeatable power feedback. The throttle reading can even provide the race team with precise details of when control is momentarily lost due to unexpected track bumps affecting the riders grip.

EPT series 1200 pressure sensors provide dynamic and high speed brake pressure information from a very rugged yet compact high strength stainless steel packaged design. Measuring up to 400bar, the hermitically welded, thin film measuring cell and high level output circuit technology ensures this sensor is suitable for the demanding shock and vibration levels experienced within the application. The sensors help confirm when and how the bike is losing traction and detect the minute compression changes in front and rear suspension.

The bikes unique front swing arm suspension system with hub-centre steering design can be attributed to two mechanical engineering students in the 1980’s as a graduation project with additional development carried out by the Italian Bimota Company and later by Vyrus of Rimini. The history should also include thanks to the British engineer Jack DiFazio for the hub-centre steering system he developed in the 1970’s and even to the 1920’s Neracar motorcycle that attempted to improve the limitations imposed by front forks for combined steering and suspension.

These previous designs suffered from production quality and weight problems but as materials and manufacturing technology moves on there is strong optimism that hub-centred steering could make a big difference to the motorcycle racing industry and even prove a safer and more durable design for road bikes.

Northampton based Alto Performance Racing, led by brothers Ben and Aarron Shaughnessy with rider Phil Read, raced in the same competition last season with a traditionally front forked Laverda 750cc and finished in third place with fifty percent podium positions. For this year’s Thunderbike series, which is based upon strict power-to-weight ratio rulings, the team and rider remained the same - so the new chassis and steering design has a definitive benchmark to compete against.

Ben Shaughnessy, the Alto Team Technical Director, said: ‘This is a genuine attempt to race and demonstrate this technology to its natural winning conclusion - and to show that motorcycle forks and frames are truly ‘old fashioned’ and in need of newer technology.’