· Cost-optimized sensor for basic ESP® functions
· Signal processing in the system control unit
· Variable design provides wide scope of applications
Bosch has extended its steering-angle sensor offering to include a new cost-effective model. The LWS6 meets all standard requirements of today’s safety and comfort systems, and is therefore especially suitable for 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 recently went 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 new LWS6 measures relatively over an unlimited measuring range. Its typical steering-angle signal resolution is 1.5 degrees. The LWS5 steering-angle sensor, which is based on GMR (giant magneto resistance) technology, measures absolutely. The LWS6 steering-angle sensor, by contrast, 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. Moreover, due to the incremental measuring principle of the LWS6, it no longer has to be calibrated by the automakers. Thanks to the new concept used in the LWS6, Bosch has reduced the cost, not only of the sensor, but also of the system as a whole – and has therefore also made a further contribution to achieving the goal of “safety for everyone”.
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. As with the LWS5, the LWS6 does not require stand-by current when the vehicle is parked. Customer-specific designs offer extensive adaptation options for a variable steering column installation or integration into the switch unit. The new Bosch sensor has been developed in accordance with current environmental requirements and is made of lead-free components.
Robert Bosch GmbH – Automotive Equipment