Magnetic sensor makes accelerator pedal fast

Deflection of the pedal is immediately converted into an electrical signal

Magnetic field sensor accelerates pedal Fraunhofer Gesellschaft
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Gas and brake pedals must react quickly and reliably if they are not to endanger the passengers unnecessarily. Now researchers have developed a 3-D magnetic sensor that detects the pedal deflection digitally through the angle.

In a full braking as in an overtaking maneuver in which the driver has misjudged, often split seconds decide on life and death. The brake and accelerator pedals must therefore react quickly. If the driver steps on the gas pedal, he twists a disc over an elaborate mechanism. Several magnetic field sensors near the disk detect the angular velocity. A linear movement is thus converted into a circular and this in the electrical signal that is used to control the engine respectively brake. The conversion takes time, is technically complex and makes the whole system expensive.

Researchers at the Fraunhofer Institute for Integrated Circuits IIS have developed a new method to immediately convert the displacement of the gas pedal into an electrical signal. "The signal chain to the computer control system is thus digitally digital - the error-prone translation mechanisms can also be dispensed with, " explains marketing director Klaus Taschka. "Below the gas pedal sits our sensor, which measures the magnetic field simultaneously in all three directions and up to 0.1 degrees. This is unique in the world. "

Like its one-dimensional predecessors, the sensor measures based on the

Hall effect: If there is a current through conductors in a magnetic field, the electrons are deflected laterally. This corresponds to a transverse voltage that is proportional to the magnetic field strength. The sensor is manufactured using cost-effective CMOS standard methods. It is located on a chip on which the researchers have integrated most of the transmitter. display

To quickly detect faults, the sensor monitors itself: A small coil surrounding it is periodically turned on. The additional magnetic field is measured by the sensor. Should it be defective, no extra signal arrives in the vehicle control. So the driver can be informed about the error.

Developers at BMW have already tested the magnetic sensor in the lab more closely; Tests on gas, brake and clutch pedals are planned. Thanks to its 3-D measurement principle, the sensor can also detect the position of car headlights, joysticks or other moving machine parts.

(Fraunhofer-Gesellschaft, May 9, 2005 - NPO)