sensors & systems - Industrial Technology Magazine

SENSORS & SYSTEMS
Autosport
Performance at high speeds
Position, pressure and temperature sensors are key in an improved motorbike suspension design
The 2008 Thunderbike motorcycle championship
represents a new beginning both for Alto
Performance Racing and for the sport. With its
unique Vyrus 994cc bike featuring a front swing
arm suspension system with hub-centre steering, the
Alto team is pioneering a design conceived decades ago
that modern materials, production technologies and
electronics systems have now made a race winning
reality. 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 uses sensors from Variohm
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 speed.
These real-time readings combine to pin-point
information delivered from the bike’s 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 Variohm's 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 bike’s 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° 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.
Dynamic, high speed information
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
hermetically 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 bike’s unique front swing arm suspension system
with hub-centre steering design can be attributed to two
mechanical engineering students in the 1980s 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 1970s and even to the
1920s Neracar motorcycle that attempted to improve
the limitations imposed by front forks for combined
steering and suspension. It is true to say that these
previous designs suffered from production quality and
weight problems but as materials and manufacturing
technology moves on there is strong optimism that hubcentred
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 will
remain the same – so the new chassis and steering
design has a definitive benchmark to compete against.
Ben Shaughnessy, the Alto Team technical director
who has always had a passion for hub-centre steering
and took six months off from his ‘day job’ running the
team to develop the design says: “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. Thanks to our mostly British based
sponsors like Variohm, who have provided world leading
engineering and technology solutions, we have the
best possible chance to succeed.”
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INDUSTRIAL TECHNOLOGY • May 2008