Steer-By-Wire Control Architecture With Asymmetric Redundancy
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Solution Overview
Problem
Existing steer-by-wire steering systems are costly due to redundant and similarly structured control units, which do not allow for efficient task assignment and optimization of computational resources.
Innovation Solution
A steer-by-wire steering system with two control units of differing complexities, where one control unit is less powerful than the other, allowing specific tasks to be assigned based on requirements, and enabling communication between them to outsource computations and reduce overall system costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two redundant and similarly structured control units are used, then system reliability is improved, but system cost and complexity increase
Solution Approach 1:
The patent applies asymmetry by designing two control units with different complexity levels - a first control unit with higher computational performance and a second control unit with lower computational performance. This asymmetric configuration allows the system to maintain redundancy for reliability while reducing overall complexity and cost, as the less complex unit can handle specific simpler tasks independently.
Solution Approach 2:
The patent segments the control functions between two specialized control units rather than using two identical general-purpose units. The first control unit handles complex computational tasks while the second handles simpler tasks, allowing each unit to be optimized for its specific function and reducing overall system complexity.
2Reliability
If two redundant and similarly structured control units are used, then system reliability is improved, but system cost increases
Solution Approach 1:
By using asymmetric control units with different complexity levels, the system maintains the reliability benefits of redundancy while reducing manufacturing costs. The less complex second control unit can be manufactured more cheaply, and the system still achieves reliability through the redundant architecture where either unit can independently control the steering actuator.
3Productivity
If computational tasks are distributed between control units, then computational efficiency is improved, but control unit complexity increases
Solution Approach 1:
The patent applies local quality by assigning specific computational tasks to specific control units based on their capabilities. The first control unit handles complex computational tasks requiring high processing power, while the second control unit handles simpler tasks. This localized task assignment optimizes computational efficiency without requiring both units to have high complexity.
Data Source
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Figure 3a~3b
AI summary
The invention relates to a steer-by-wire steering system (1) for a motor vehicle, comprising a rotatably mounted steering spindle (3), a feedback actuator (4) having a feedback motor (8) for acting on the steering spindle (3), a steering actuator (5) having a steering motor (10) for acting on the steered wheels (6) of the motor vehicle according to the rotation of the steering spindle (3), and two control units (9, 11) for controlling the feedback motor (8) and the steering motor (10). A first control unit (9) of the two control units and a second control unit (11) of the two control units have differing levels of complexity to one another, in particular in that the first control unit (9) is more efficient than the second control unit (11). The invention also relates to a method for operating a steer-by-wire steering system (1), wherein the first control unit (9) and the second control unit (11) carry out procedures of differing levels of complexity to one another.