Displacement Sensors in Formula 1

The success of a racing car depends on hundreds
of components working together at peak performance
under the most extreme conditions.

Components such as displacement sensors are designed to control and
monitor a growing number of vital functions on racing cars and supply
information to engineers that help trim precious seconds off the car’s lap times.

Whilst most categories of motor racing do not allow the performance of the
suspension to be modified during a race, the use of computerised data logging
in testing and practice allows race engineers to tune the suspension to match
the particular conditions and type of circuit.

Using displacement sensors to monitor the movement of the suspension
allows electrical signals (indicating the position of the dampers) to feed
back to the logging/telemetry system and then display a graphical representation
of the car’s performance around a track. Using the data, engineers can easily
recognise areas where improvements can be made, and fine-tune the car by
adjusting ride heights and stiffness, to suit a particular track and driver.

Movement of the suspension can be sensed by a linear displacement sensor
such as a potentiometer or LVDT, attached alongside or in close proximity to
the suspension damper. The sensor ideally needs to be protected from ingress
of fluids and particles. In some applications, rotary movement of the suspension
linkage can be used to attach a rotary displacement transducer, such as a
rotary potentiometer or RVDT.

The use of linear or rotary potentiometers provides a simple solution, operating
from a DC voltage and providing a signal proportional to the movement of the
sensor shaft. The high cyclic rate of movement requires a high sensor
specification with low noise tracks and protective seals to provide
operational long life.

In the search for ultimate reliability many of the teams in Formula 1 have
switched to LVDT displacement sensors for suspension monitoring.
The LVDTs are normally custom-built to suit the particular installation and
will provide a longer, maintenance-free service life. Although LVDTs
require more complex signal conditioning, most suppliers of data logging
equipment can provide suitable modules to interface with a number of LVDTs.

Throttle control
Throttle control is another area where displacement transducers are playing
a key role. Most throttle control systems have a rotary motion, so a rotary
displacement transducer, either a potentiometer or RVDT, can be attached
to the linkage. The position of the throttle mechanism is usually in a very hostile
environment such as the top of the engine or underneath air intake ducts, so
either device must be extremely rugged and able to withstand high levels
of shock, vibration and high temperatures.

Special ‘paddles’ on the driver’s steering wheel electronically control the clutch
actuating mechanism on today’s high-performance racing cars, overcoming the
need for the driver to use his feet to engage or disengage the clutch.

This arrangement allows faster up-changing and down-changing of the gearbox
during acceleration and braking. For closed-loop control of the paddle
mechanism a linear displacement sensor is attached to the clutch actuator
to provide position feedback information to the engine management system.
As the sensor is exposed to extreme vibration from the engine and
transmission assembly, most Formula 1 cars are fitted with a small footprint,
high integrity, short stroke LVDT. Unusually, the Penny & Giles LVDT
specified by many teams is based on a standard industrial model that
uses welded stainless steel construction, a brazed core assembly and
coil terminations specially designed to ensure they survive high vibration
and shock.

When it comes to braking, recent developments in GT and Formula 1 brake
caliper design have enabled systems to be fitted to monitor the wear of the
brake pads and discs during a race. Advising the driver to back off by one
second a lap can make a significant difference to brake wear.

The movement of the brake caliper piston is sensed by a very small LVDT
embedded in the caliper body, which has been specially designed to withstand
extremes of shock and vibration from the track, as well as the high temperatures
from the brake discs. The back of the brake pads can reach temperatures as
high as 400°C, whilst the caliper body can reach 150-200°C.

On Formula 1 cars up to eight LVDT sensors per car are fitted (one per side,
per caliper, per wheel, if pad wear sensing is fitted to front and rear wheels).
The signals from the LVDT are fed to the car’s data acquisition system and
can tell race engineers the condition of the brake pad and disc wear

Other sensing applications that are helping to improve motorsport include
gear position selection (LVDTs), steering rack position (multi-turn
potentiometers) and oil reservoir level (LVDTs).

For more information, please contact:-

Mike Iles at Penny & Giles Controls Ltd. 15 Airfield Road, Christchurch BH23 3TJ. UK
Tel: +44(0)1202-409409  Fax: +44(0) 1202-409475
Email:  Website:

June 2000

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