Bosch's latest sensor supports basic ESP functions and integrates signal processing in the system control unit.
Bosch has extended its steering-angle sensor offering to include a new cost-effective model. The vendor claims that the LWS6 meets all standard requirements of today's safety and comfort systems. The device targets ESP applications in compact class vehicles and classes further down the scale. The signals from the LWS6 can also be used, however, for systems such as electro-hydraulic power steering or ACC adaptive cruise control. The sensor went these days into series production.
Steering-angle sensors measure the steering wheel's actual position, the value which an increasing number of systems use to determine the direction the driver wants the vehicle to take. The LWS6 measures relatively over an unlimited measuring range. Its typical steering-angle signal resolution is 1.5 degrees. In contrast to the established model LWS5, which is based on GMR (giant magneto resistance) technology and thus measures absolutely, the LWS6 uses the Hall effect. For this purpose, a multipole magnet is fixed to the steering column. Hall elements detect changes in the sensor's magnetic field without contacts and without gear wheels.
As two or more Hall elements are used, any rotary motion generates square-wave signals, which show a certain phase shift relative to each other. These square-wave signals are transmitted directly to the control unit, thus ruling out any need for evaluation logic in the LWS6. Processing of the sensor signals is done by the system control unit, which calculates the position, rotation direction, and rotation speed of the steering wheel.
The control unit also validates the sensor output signals and detects short-circuits, for example. Due to the incremental measuring principle of the LWS6, it no longer has to be calibrated by the car OEM. The new concept used for the LWS6 enabled Bosch to reduce the cost, not only of the sensor, but also of the entire system.
As there is no mechanical link between the Hall measuring elements and the magnetic hub, the sensor is wear-free. Unlike optical sensors, the magnetic measuring principle makes the LWS6 resistant to contaminants, such as dust, which find their way into the housing over the course of the device's service life. Customer-specific designs offer adaptation options for a variable steering column installation or integration into the switch unit.
Courtesy of Automotive DesignLine Europe.