Steering of Multi-Axle Vehicles

There is an increasing demand for the operation of very long vehicles with high transport capacities. These vehicles are often equipped with a multi-axle steering system in order to maintain their maneuverability. In recent years, conventional mechanical-hydraulic multi-axle steering systems have often been replaced by electronically controlled steering systems, also called steer-by-wire systems. These systems are much more flexibly configurable and can significantly increase the vehicles’ maneuverability through the use of more complex steering strategies.

The Fraunhofer IVI has been working in the field of multi-axle steer-by-wire systems in the context of various research and development projects since 2002. Fundamental methodological developments that explicitly integrate physically based vehicle models were tested and optimized using the institute's own test vehicles (AutoTram^® and ELENA). One particularly efficient approach to multi-axle steering was patented.

In collaboration with Göppel Bus GmbH, the Fraunhofer IVI designed a special steer-by-wire multi-axle steering system for the AutoTram^® Extra Grand, an extremely long double-articulated bus. The concept was implemented in collaboration with additional partners and tested successfully. A second multi-axle steering system was constructed with another industrial partner for a special-purpose vehicle that is now in regular service. Additionally, a number of specialized solutions for steering systems were developed on commission by different industry clients and analyzed with the help of simulation.

Overview of Competencies

• Kinematic and kinetic vehicle modeling for the simulation of cornering characteristics and vehicle dynamics
• Methods for a systematic, model-based design of steering processes
• Testing and optimization of steering systems with the help of simulation 
• Rapid prototyping technology and measurement technology for test drives
  
• Implementation and launch
• Specification of requirements and safety assessment
• Assistance systems for an improved handling of multi-axle vehicles and vehicle-trailer combinations

• Development, implementation and testing of an electronic multi-axle steering system in the context of the »Wachstumskern AutoTram^®« (30.7-m long vehicle with three steer-by-wire axles)
• Demonstration of model-based driving on a preset lane with satellite-based lane detection using the example of the AutoTram^®
• Development of assistance functionalities: Demonstration of a reversing maneuver without any jack-knifing using the example of test vehicle ELENA 
  

• Engineering in the field of multi-axle steering systems (design, simulation, implementation and testing)

A broad network of interdisciplinary partners is available for the development of comprehensive solutions.