Browse Prior Art Database

LOW COST AUTOMOTIVE ABSOLUTE ANGULAR POSITION SENSOR

IP.com Disclosure Number: IPCOM000007169D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2002-Mar-01
Document File: 2 page(s) / 105K

Publishing Venue

Motorola

Related People

Marc Osajda: AUTHOR [+2]

Abstract

Conventional methods for absolute position sens- ing in an automotive environment include potenti- ometers (variable resistance) and systems usmg mag- netic or electromagnetic properties (hall effect, variable reluctance, LVDT).

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MOTOROLA Technical Developments Volume 22 June 1994

LOW COST AUTOMOTIVE ABSOLUTE ANGULAR POSITION SENSOR

by Marc Osajda and Jean-Jacques Rolland

encoded word. No two words are alike. So the true position can always be precisely determined at any time. The nature ofabsolute position sensors makes them effective in applications where it is inconven- ient or difficult to reset the sensor (ex: suspension position, steering wheel position,. .).

This design uses a cylinder (code drum Figure
1) in lieu of a standard disc in order to avoid the need for expensive, precise position detection on tracks close to the center ofthe disc. All tracks have the same precision as the outside disc track for the same sensor outside diameter.

Standard optical components and mass produc- tion processes (no individual adjustment) can be used.

BACKGROUND

  Conventional methods for absolute position sens- ing in an automotive environment include potenti- ometers (variable resistance) and systems usmg mag- netic or electromagnetic properties (hall effect, variable reluctance, LVDT).

  Since the output signal is typically an analog signal in all these systems (due to the technology), an A/D converter is necessary to use this output signal in combination with a MCU.

  In addition, in a harsh environment like those found in automotive applications, analog signals may be disturbed by such factors as loss in wires, tarnished contacts, temperature, reliability, EMI. Thus, sen- sors used in these environments that have high res- olution and accuracy are very expensive.

  Absolute encoders, using light interruption prin- ciples with accurate coded disc are available but there very expensive for use in automotive applications. DESCRIPTION

  This design is an absolute angular...