Steer-by-Wire Dual Actuation for Fail-Safe Steering Forces
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Solution Overview
Problem
Existing steer by wire systems lack redundancy and fail to provide a wide range of steering forces, making them unreliable in case of actuating arrangement failures.
Innovation Solution
A dual actuating arrangement is implemented, comprising two electric motors and hydraulic units, each connected to the steering mechanics, ensuring that if one fails, the other can continue to operate, providing redundancy and a wide range of steering forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single actuating arrangement is used in steer by wire systems, then the device complexity is reduced, but the reliability decreases because the system fails when the actuating arrangement fails
Solution Approach 1:
The actuating arrangement is segmented into two independent subsystems (first actuating arrangement with first electric motor and first hydraulic unit, second actuating arrangement with second electric motor and second hydraulic unit). Each subsystem can independently perform the steering function, allowing the system to maintain reliability even when one subsystem fails. This segmentation directly resolves the contradiction by enabling redundancy without creating a single point of failure.
Solution Approach 2:
Different parts of the actuating arrangement have specialized functions: electric motors provide mechanical power, hydraulic units provide fluid pressure control, and sensors provide feedback. By optimizing each local component's quality and function, the overall system achieves high reliability while managing complexity through functional specialization rather than uniform design.
2Force
If a single hydraulic unit is used, then the device complexity is reduced, but the range of steering forces is limited
Solution Approach 1:
The hydraulic system is segmented into multiple hydraulic units (first hydraulic unit and second hydraulic unit), each capable of independently generating and controlling hydraulic pressure. This segmentation allows the system to provide a wide range of steering forces by activating one or both hydraulic units depending on the steering demand, resolving the contradiction between force range and complexity.
Solution Approach 2:
The hydraulic system is designed to be dynamic, allowing the hydraulic pressure and flow to be adjusted in real-time based on steering requirements. The multiple hydraulic units can operate at different pressure levels and flow rates, enabling the system to adapt to varying steering force demands while managing complexity through dynamic control rather than fixed design.
3Reliability
If redundant actuating arrangements are implemented, then the reliability is improved through fail-safe operation, but the device complexity increases
Solution Approach 1:
The first and second actuating arrangements are merged into a unified steer by wire system with common control logic and integrated feedback mechanisms. The controller coordinates both actuating arrangements, allowing them to operate independently or in coordination. This merging approach achieves fail-safe operation while managing complexity through unified control rather than completely separate systems.
Solution Approach 2:
The system uses a copied configuration where the second actuating arrangement replicates the functional capabilities of the first actuating arrangement. Both arrangements have similar components (electric motor, hydraulic unit, sensors) that can perform the same steering function. This copying strategy provides redundancy for fail-safe operation while maintaining manageable complexity through standardized design patterns.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures fail-safe operation by maintaining steering functionality even if one actuating arrangement fails, allowing safe vehicle operation and enhanced steering force flexibility.
Implementation Method 1
the first actuating arrangement comprises a first electric motor, which is in connection to the steering input device, and a first hydraulic unit, which is operatively coupled to the first electric motor
Implementation Method 2
The hydraulic unit provides a hydraulic fluid to the steering mechanics, comprising at least one hydraulic cylinder, to steer the vehicle
Data Source
Figure 1~3
AI summary
The present invention relates to steer by wire system (1) for steering a vehicle with a steering mechanics (8), the steer by wire system (1) having a steering input device (2) and a first actuating arrangement (5), wherein the first actuating arrangement (5) comprises a first electric motor (5a), which is in connection to the steering input device (2), and a first hydraulic unit (5d), which is operatively coupled to the first electric motor (5a), wherein the first hydraulic unit (5) is configured to be fluidly connected to the steering mechanics (8). The objective of the present invention is to provide a steer by wire system (1) having a large range of steering forces. This objective is solved by a steer by wire system (1) comprising a second actuating arrangement (6) being structured and coupled analogously to the first actuating arrangement (5).