Control Strategies

To develop strategies for chassis control we concentrate on the modelling and simulation of both chassis and powertrain systems. We are exploiting the synergies and interactions between the chassis and the power train to achieve optimal results for active safety, efficiency, and driving comfort at a low cost. Advanced optimisation techniques are used both in terms of control and as part of our design process.

Integrated Chassis Control

With the rising number of available active chassis systems the need for their adequate coordination increases, at the same time allowing for optimal exploitation of synergies. Moreover, the large amount of equipment options for mass production vehicles demand for an integrated control design approach which overcomes the confusing situation specific operation of present vehicle dynamics control systems.

A concept for integrated chassis control is in the focus of past and ongoing development at our institute [Bünte et al. 2006c ; Bünte & Andreasson 2006c; Andreasson & Bünte, 2006c; Knobel et al. 2006c]. Targetting at a given vehicular motion request, the control signals are computed for the actual set of available chassis actuators (which may be deteriorated e.g. in case of a failure). The available actuator degrees of freedom are exploited in an optimal fashion to maximise the safety margin while minimising fuel consumption and tyre wear. The transparent control concept is characterised by the fact that it uses a single structure [Bajcinca & Bünte 2005c] and fixed parameters for all vehicle configurations and driving situations. Apart from real vehicle dynamics control, the approach may be used for assessing the benefit of novel mechatronic chassis systems.

Vehicle Energy Systems

This specific topic is organised in the DLR research area of the same name. The objective is to research on and to provide new concepts for propulsion technologies to substantially reduce fuel consumption and emissions and to investigate alternative fuels. The project is pursued jointly by several DLR institutes. The scientific questions along with this project aim at the further development of system-theoretical principles and process modelling concerning propulsion systems to increase the range, efficiency, and performance of alternative vehicles.

Our contribution focuses on the system-theoretical and modelling aspects. Due to the extensive coupling of technological and systems-dynamics aspects, the development of low energy consumption and low-emission vehicle technologies requires the integration of mechatronic approaches to an increasing extent. These approaches need both theoretical principles of modelling and simulating combined with optimisation methods as well as the development and provision of appropriate tools. Therefore, the Modelica library AlternativeVehicles was initiated. Optimised operating strategies have been developed and tested. In a next step, criteria relating to driving dynamics will also be taken into account.

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