Steer-By-Wire Control Unit Partitioning for Lower-Cost Redundancy
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Solution Overview
Problem
Existing steer-by-wire steering systems are costly due to redundant and equally complex control units, which increases the overall system expense without reducing functionality.
Innovation Solution
A steer-by-wire steering system with two control units of different complexity levels, where one control unit is designed for high-level software execution and the other for low-level software, allowing for cost-effective design and task assignment based on requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant and equally complex control units are used for feedback and steering control, then system reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by assigning different complexity levels to different control units based on their specific functional requirements. The feedback control unit and steering control unit are designed with different computational capabilities, where each unit has the appropriate level of complexity for its designated tasks rather than both being equally complex. This resolves the contradiction by maintaining reliability through adequate control functionality while reducing manufacturing costs by avoiding unnecessary complexity in each individual unit.
2Reliability
If equally complex control units are used for feedback and steering control, then functional redundancy is improved, but device complexity increases
Solution Approach 1:
The patent implements local quality by differentiating the complexity characteristics of control units according to their specific functional demands. The feedback control unit and steering control unit are designed with tailored computational capabilities matching their respective tasks, achieving functional redundancy without requiring identical complexity levels. This reduces overall device complexity while preserving the necessary redundancy for reliable operation.
3Measurement precision
If high-performance control units are used for both feedback and steering control, then control precision is improved, but cost increases
Solution Approach 1:
The patent applies local quality by matching control unit performance to the specific precision requirements of each control function. The feedback control unit and steering control unit are equipped with different levels of computational performance based on their respective precision demands, rather than both using high-performance units. This maintains adequate control precision for each function while reducing manufacturing costs by avoiding over-engineering.
Data Source
AI summary
A steer-by-wire steering system for a motor vehicle may include a rotatably supported steering spindle, a feedback actuator with a feedback motor for acting on the steering spindle, a steering actuator with a steering motor for acting on steered wheels of the motor vehicle based on rotation of the steering spindle, and two control units for controlling the feedback motor and the steering motor. A first control unit of the two control units and a second control unit of the two control units have different levels of complexity relative to each other, in particular such that the first control unit is more powerful than the second control unit. Also, a method can be utilized to operate such a steer-by-wire steering system, whereby the first control unit and the second control unit execute procedures of different complexity relative to each other.