APPLICATION STORY

 Formula One Technology for Industry



In today's high-tech world of motor racing, winning depends on the performance of components such as displacement sensors. These sensors are widely used in Formula One racing and other racing series to control and monitor a number of critical control functions that will trim a few tenths of a second off a car's lap time - this being the difference between success and failure! The use of displacement sensors and a computerised data logging system allow the race engineer to perfect the performance of a racecar for individual circuits during pre-race practice. Data from the car is transmitted via the onboard telemetry system after each lap of the circuit. This data is displayed graphically on a computer screen so the engineer can advise the driver how the car is performing at various parts around the circuit. After each practice run the car returns to the pits so that the mechanics can make immediate adjustments to the suspension, wing settings etc. Before the introduction of these computerised data logging systems, the race engineer had to rely on the ability of the driver to supply the necessary information. This technology is also used to evaluate and assist young drivers as they learn to compete at the highest levels of their sport. Ultra Slim Linear Potentiometer Used in areas where compactness and reliability are a design consideration. Throttle pedal measurement is a typical example.
Applications requiring displacement sensors on a racing car are numerous and depend on the race series. These sensors have to operate in a hostile environment and are subjected to extreme vibration and high temperature. This requires racing teams to demand a level of sensor reliability normally reserved only for the aerospace industry. The most successful displacement sensor manufacturer to exploit the developments in motor sport electronics throughout the last decade has been Active Sensors. Formed in 1992 in Christchurch, Dorset the company developed motor sport sensors using aerospace technology. Active works in partnership with the engineers responsible for the control and data-logging systems in the UK and overseas (50% of the sensors manufactured by Active are exported). Rotary Potentiometers They convert rotary movement into a proportional voltage output. Throttle actuating, gearbox actuating and chassis movement are typical examples.
To keep on the pace of new developments all the teams design a new car every year. Very few chassis and engine components are carried over into the new season and the car has to get from the CAD system to the test track in less than twelve weeks. A build schedule this demanding requires a rapid response from all their suppliers. Active Sensors achieves this by investing strategically in engineering personnel, and in the latest CNC technology that will carry out all the company's machining requirements in-house. The creation of a composite materials laboratory for sensor element production also allows faster design and manufacture. Communication between the race team and its component suppliers is important to the success of the new cars development and the right decisions at this stage will save many hours of frustration at the test track. Linear Potentiometers Designed to convert a linear movement into a proportional voltage output. Suspension movement and motion system feedback sensors are typical uses.
Control Throttle control in Formula One is a closed loop electro-hydraulic system (fly-by-wire) that requires a displacement sensor on the driver's pedal and one on the actuating mechanism mounted on the engine. This arrangement allows faster acceleration and also preserves the engine life by restricting over revving during a race. The pedal sensor is normally a special design, twin output linear potentiometer with a measurement range of 50mm (the pedal displacement). A twin output sensor is specified for system integrity. If the signal from either sensor is lost then the car stops! The on-board computer monitors both output signals from the throttle pedal and engine mounted sensors. If an error develops on either output signal, the computer switches to the other (known as redundancy). The engine-mounted sensor is either a high performance rotary potentiometer or RVDT (rotary variable differential transformer). Rotary sensors are specified for the throttle actuating mechanism as carburettors are rotary in design and have relatively small angles of movement (approximately 90 degree's rotation). The clutch operation is also a closed loop electro-hydraulic system. The driver operates the clutch by moving a finger paddle mounted behind the steering wheel. This arrangement can improve the handling of the car through corners as the drivers can then keep their left foot on the brake pedal to control their speed (commonly known as left foot braking). Wire Operated Sensors Designed to work where there are installation difficulties. The sensor body is located away from the component that requires measuring and is connected via the wire.
As space on the steering wheel is limited, one of the sensors that can be used is a miniature rotary potentiometer. This would be fitted directly to the driver's wheel with the connections to the system loom being made through the steering column via a multi-pin connector. This multi-pin connector also carries the signal connections for the gear select switches, the radio and the steering wheel dash LCD display. The sensor mounted on the clutch actuating mechanism is a special design short stroke LVDT (linear variable differential transformer). The LVDT would have a measurement range of approx 6mm and due to limits on installation space, have a short body to stroke length ratio. The clutch control sensors would also have twin outputs for total system integrity. As most racing cars are designed with a sequential gearbox (similar to a motorbike gearbox) the gear change is also operated from the steering wheel by means of a simple push button switch. This is known as a semi-automatic gearbox and allows for a quicker gear change because the drivers can keep their hands on the steering wheel at all times. A sequential gearbox also allows more control of gear selection using clever control software. A racecar can now go from sixth gear at top speed straight into second gear at the push of a button. This is a very useful aid to the racing driver as they can concentrate on cornering rather than looking for the right gear. The car will accelerate through the gears as normal until the next braking point and the process is then repeated. The sensor used as the feedback device to position the gearbox actuator is a high performance twin output rotary potentiometer. The potentiometer is preferred to a RVDT because of its angular range capability (typically 350 degrees). Not all gearbox operation is semi-automatic and in other racing series a manual gearbox is used. These gearboxes are also fitted with a rotary sensor to give gear selection indication only (no control capability). This sensor would be a single output rotary potentiometer because redundancy is not necessary, as sensor failure would not stop the car. LVDT & RVDT Sensors LVDT's are often used on clutch actuation and for monitoring brake disc wear RVDT's are ideal for throttle actuation mechanisms.
Measurement One of the area's in motor sport where the displacement sensor is having a lot of success is in suspension movement measurement. All race car's are effected by the slightest change in the suspension set up, so the more information a racer has, the more chance they have of winning. The signal from a linear or rotary potentiometer is fed into a data logger mounted on the car. This data logger will then transmit the signal to the pits via a radio, or it can be down loaded when the car returns to the garage. A race engineer will examine this information on their computer screen and calculate any adjustments that may be needed to the suspension. Another area of continuous development is the braking systems used in motor racing. Brake disc wear is now monitored with the mounting of a miniature linear sensor (LVDT) in the brake calliper. As brake disc width and diameter is controlled by the rulebook (28mm width in F1), hard braking circuits can wear a disc by as much as 50%. This is probably the harshest environment for a sensor on a racecar as brake disc temperatures can reach 800 degree's C under braking. Hydraulic fluid level measurement is also achieved using displacement sensors mounted in the fluid reservoirs. Due to the corrosive nature of most system fluids, a sensor with a sealed construction and high specification wiring would be specified. This measurement is made using either a linear potentiometer or LVDT depending on the signal conditioning available in the electronics system. Industry Formula One racing is probably the most demanding automotive application for control and measurement sensors. General vehicle manufacturers also take advantage of the latest technology to help develop modern cars and trucks. These developments by Active have enabled the company to increase the range of their industrial displacement sensors based on fly-by-wire technology. Industries to benefit are flight simulation, manufacturing, power generation, hydraulic & pneumatic control and scientific research. Typical applications include sensors for positioning systems in machine building, speed control of rollers in the converting industry and feedback sensors in robotics. The company's developments have kept the likes of Schumacher, Hakkinen and Coulthard on track using the latest technology. Formula One technology is now available to industry and with it's proven track record it is hard to beat! _______________________________________________________ For further information about Active Sensors product range call them on +44(0) 1202 480620 or visit their web site: www.activesensors.com November 2000
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Why not submit your Application Story ... Contact Mike Coope - Tel: +44(0) 1902-700973 or Email: sensland@aol.com