Conventional steering models are typically based on a simplified approach that does not consider non-linear friction effects, stiffness, mass, inertia, etc. The achievable simulation result is described as an “out-of-true,” non-authentic steering or handling “feel.” In addition, a comparison between the simulation results and the physical drive test reveals significant differences.

The integration of the Pfeffer steering model into the open CarMaker integration and testing platform is truly sensational in this context. Combined with the “SensoWheel” steering simulator it produces a very realistic reflection of the steering and handling feel, as numerous test users have confirmed. Even small modifications to the vehicle such as suspension kinematics, springing, tires, weight distribution and aerodynamics are equally identifiable and perceptible as active control interventions and changing road conditions. In addition, special importance was attached to extremely easy parameterization and operation plus a wide range of possible applications.

In combination with the fully non-linear car model, IPGCar, the high-performing driver model for demanding closed-loop driving tasks, IPGDriver, and the new tire model extensions for the stop-and-park model (Turn-Slip) almost any driving situation can be precisely modeled.

Realistic steering feel is primarily the result of the steering torque in the driver-vehicle-tire-road interface. In addition, the perfect interaction between the mechanical model and the steering assistance unit ensures the precise modeling of steering characteristics. Therefore, a strong focus was put on detailing the individual steering components, modeling the mechanical friction mechanisms with friction mechanisms and the implementation of the various steering assistance systems in order to achieve a good and authentic reflection of the steering torque.

From the steering assistance unit the following selections can be made from five models in the GUI: hydraulic steering assistance (HPS, power steering), electrical assistance at the steering rack (EPSapa = Axially Parallel Drive) plus electrical assistance at the steering column (EPS to Column) in which the support may be defined at the upper steering column (Column) or at the pinion. Both of the two EPS models are available as simplified or as detailed steering assistance models with additional mechanical degrees of freedom. Depending on the type of axle selected, steering is automatically configured in front of or behind the axle in CarMaker. This complex interaction produces a highly resolved, detailed image of reality.

The steering model has been extended by the proven CarMaker ModelManager, which enables the various model parts to be conveniently selected in the GUI. This means that the user does not have to deal with cumbersome integration, initialization and clean-up of the models. All parameters of the selected model are automatically allocated and are available on the dynamic interfaces plus for data storage. Due to the modular structure and extensive interface structure model parts may be replaced or extended as needed by means of the bypass model – for example by the user’s own steering support systems, by e-machines or controllers. Furthermore, various bypass interfaces for external torque, angles, positions, electric power etc. were created in order to model an active steering recommendation using torque, desired steering angle specifications or targeted error injections.