Angle sensor: Magnetostrictive device helps stop world’s fastest car

Two Model MS Temposonics magnetostrictive sensors mounted in the Bugatti Veyron’s rear-wing supports help raise the wing to improve braking effectiveness at high speeds. Source: MTS Systems Corp. Sensors Division

Being the world’s fastest street-legal passenger car is all very nice, but what happens when the lady pushing the baby carriage steps off the curb at just the wrong moment? At that point, it’s time to have the world’s best brakes as well!

The Bugatti Veyron actually is touted as the world’s fastest street-legal motor vehicle. To help its stopping performance match its get-up-and-go performance, MTS Systems Corp. Sensors Division has adapted its mobile hydraulic (Model MS) Temposonics magnetostrictive sensor to help the vehicle’s aerodynamics package add downforce needed when the vehicle brakes. The company says the sensor’s precision, speed, and reliability are critical to operation of the Veyron’s aerodynamic rear wing, which helps the car brake quickly. Two of the sensors are used for height adjustment, and one sensor is used for angular adjustment monitoring control.

‘Bugatti engineers needed a compact position sensor that was rugged, accurate, and reliable,’ said Drew Smedley, director of global marketing at MTS Sensors. ‘The modular construction and high electronic flexibility of our Temposonics technology made the MS sensor the ideal solution.’

The Bugatti Veyron can reach speeds of more than 200 mph. These high speeds require extra braking power, which comes by raising the rear wing and generating additional braking force. The Veyron can decelerate from 230 mph to 0 mph in only 7.5 seconds, largely due to the extra down force achieved with the rear wing, which is raised within 0.4 sec to a 55° angle.

According to MTS, MS sensors fitted into the wing’s hydraulic cylinders measure the wing angle directly. The sensor housings and measuring pipes are made of stainless steel, so environmental factors such as dust, water and temperature variations have no affect on the measured signal. The housing contains the sensor’s electronic components, shielding them from electromagnetic interference as well.

The Temposonics principle of operation is non-contact and without wear. Based on the magnetostrictive measurement principle, it doesn’t require recalibration or resetting of reference points. To determine the wing’s position, an integrated magnet generates a sound wave by torsion in the sensing element mounted atop each hydraulic cylinder. This pulse propagates in the sensing element and is converted into a standard output signal by means of run-time measurement. A direct contact between the position magnet and the measuring element is not necessary. A highly specific mode of signal evaluation, which virtually excludes signal interference and falsification, is an additional feature that the company says is unique in the market.

The sensing element, an encapsulated and pressure-proof waveguide, is installed directly in the hydraulic piston rod. The position magnet, the sensor’s only moving part; mounts in the bottom of the piston and provides non-contact signaling to the waveguide. Conditioned measurement signals are put out by electronics integrated into the sensor housing.

MTS Sensors, a division of MTS Systems Corp., is a global developer and producer of magnetostrictive linear-position and liquid-level sensors. With the company’s patented Temposonics technology, the Sensors Division develops new ways to apply magnetostrictive sensing technology to solve critical applications in a variety of markets worldwide.

For more information, visit www.mtssensors.com .See also www.bugatti-cars.de/bugatti

— C.G. Masi , senior editor , Control Engineering Machine Control eNewsletter (Read the latest; subscribe for free using the link at the top of the page.)

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