Bidirectional Ackermann Steering for Multi-Car Path Tracking
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Solution Overview
Problem
Current multi-car mass transit vehicles, particularly roadtrams, lack a bidirectional four-wheel Ackermann-style steering mechanism, making them unsuitable for urban environments and limiting their ability to reverse without additional infrastructure or route modifications, as conventional systems are uni-directional and prone to jack-knifing when reversing.
Innovation Solution
A bi-directional steering system for multi-car mass transit vehicles, where a drawbar attached to the steering systems of first and second cars provides steering input in one direction for the first car and another direction for the second car, utilizing a bellcrank or turntable and rigid linkage arrangement, with pneumatic or hydraulic centring linkages and pistons to enable flexible movement and direction switching without the need for drawbar removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional four-wheel Ackermann steering is used, then each car follows exactly the front car's path minimizing track width, but the system cannot operate bi-directionally and will jack-knife when reversing
Solution Approach 1:
The patent applies inversion by reversing the drawbar connection configuration when changing direction. The drawbar that normally connects to the front car's steering system is reconfigured to connect to the rear car's steering system, allowing the multi-car vehicle to operate bidirectionally. This inversion of connection topology enables the same Ackermann steering mechanism to function correctly in both forward and reverse directions, eliminating the jack-knife problem while maintaining path following accuracy.
Solution Approach 2:
The patent implements dynamics by making the drawbar connections reconfigurable rather than fixed. The steering system dynamically adapts its configuration based on the direction of travel, allowing the drawbar to be disconnected from one car and connected to another. This dynamic reconfiguration enables bidirectional operation while preserving the geometric relationships necessary for accurate path following in each direction.
2Adaptability or versatility
If semi-trailer steering is used, then the system may operate bi-directionally, but the trailing cars will not follow the lead car's track accurately and may cut into corners
Solution Approach 1:
The patent resolves this contradiction by inverting the steering input source based on direction. When operating in reverse, the drawbar connection is inverted to provide steering input from what was previously the rear car, ensuring that the Ackermann geometry is maintained in the new forward direction. This inversion ensures accurate path following regardless of which end of the multi-car vehicle is leading.
3Adaptability or versatility
If additional drawbars are fitted to enable bi-directionality, then the vehicle can pull trailers in second direction, but the steering system complexity increases and drawbars must be removed for direction switching
Solution Approach 1:
The patent applies universality by designing the drawbar and steering system to serve multiple functions. The same drawbar structure is used for both unidirectional and bidirectional operations, and the steering mechanism handles both steering and direction-switching functions. This multi-functionality eliminates the need for separate drawbars for each direction and reduces overall system complexity while enabling bidirectional operation.
4Manufacturing precision
If conventional multi-trailer steering systems are used, then the trailers follow exactly the path of the lead car, but the system is uni-directional and requires additional track or road infrastructure
Solution Approach 1:
The patent implements dynamics by making the steering system reconfigurable in real-time. The drawbar connections and steering inputs are dynamically adjusted based on the desired direction of travel, allowing the vehicle to adapt to different routing requirements without infrastructure modifications. This dynamic reconfiguration enables the same hardware to provide both precise path following and flexible routing options.
Data Source
AI summary
A steering system for a multi-car mass transit vehicle, the steering system providing a four-wheel Ackermann-type system for providing improved manoeuvrability of each car and bi-directional travel, with each car accurately following the path of the car in front when travelling in either a forward or backward direction. Alternatively, there is provided: an intermediate carriage for a multi-carriage vehicle, the intermediate carriage configured to connect to first and second carriages, and the intermediate carriage including a steering input and a steering output, such that the steering input is configured to accept a steering input from the first carriage, and the steering output is configured to provide a steering output to the second carriage. Further alternatively, there is provided a tyre-wheeled bogie arrangement for a vehicle, the bogie arrangement including a bogie body and at least one wheel including a tyre.