KIT, Schaeffler optimise power steering for electric cars

March 31, 2015 // By Christoph Hammerschmidt
Power steering, this ubiquitous feature that greatly facilitates parking our vehicles, obtains its power from the vehicle’s engine. But how about electric cars? In this case, power steering draws its power from the battery - and contributes to reduce the vehicle’s driving range. A joint research project from mechatronics company Schaeffler AG and the Karlsruhe Institute of Technology (KIT) is devising concepts that makes power steering for electric vehicles more energy efficient.

„Our goal is to develop as system that gets along with fewer components which helps designers to reduce weight and energy“, explains Marcel Mayer from Schaeffler who manages the e2-Lenk project. „This in turn would be a contribution to make battery electric vehicles more affordable and at the same time would increase their driving range.“

The idea is simple: The wheels in an electric car will be driven individually by electric motors in contrast to a car with an internal combustion engine where all the wheels are provided with equal force. If the wheels on the left side transmit more drive torque to the road than those on the right side, this will result in acceleration of the vehicle to the right without the need to turn the front wheels or consume additional energy for steering. This principle is known as torque vectoring and has been used in many research vehicles like the RACE e-car from Siemens or, within limits, the Visio.M vehicle from the Munich Technical University. The joint project of KIT and Schaeffler however aims at devising a concept that can be transferred easily to series vehicles.  "Steering assistance can be provided while driving by means of an intelligent control system and suitable wheel suspension", says Mayer. "Only steering when stationary remains a challenge with conventional designs.“

The approach makes power steering a part of the drive train, says KIT researcher Michael Frey. Steering the front wheels is carried out without using additional energy. "We also want to significantly increase the quality of driving“, he explains. „Customer benefit, comfort, safety and reliability go hand in hand here."

As part of the project, functional demonstrators are being built, with which the concepts can be validated and optimized in experiments. It is also planned to implement the system in last year's Formula Student racing car KIT built by the university group KA-RaceIng with the participation of the students.

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