Active Steering Angle Conversion Control

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Solution Overview

Problem

Existing active steering systems face challenges in quickly switching between different steering ratio characteristic curves without requiring a mandatory zero crossing of the steering wheel, which can lead to abrupt changes in steering behavior and potentially cause self-steering issues, especially during cornering.

Innovation Solution

The method involves a gradual or linear change in the angular transmission ratio based on detected steering wheel movements or a predetermined time period after selecting a new characteristic curve, allowing for incremental synchronization without the need for a zero crossing, using a device that detects steering wheel movements or a timer to control the wheel steering angle adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the angular ratio is changed abruptly when switching between characteristic curves, then the steering mode switch is fast and responsive, but the steering behavior becomes discontinuous and may cause self-steering issues

Engineering Contradiction:

Improvesteering mode switch speedVSAvoidsteering behavior continuity

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent applies dynamics by making the angular transmission ratio change dynamically over time rather than abruptly. When switching between characteristic curves, the system transitions through intermediate ratio values, creating a smooth, time-dependent evolution of the steering ratio that maintains continuous and reliable steering behavior while still achieving mode switching.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements beforehand cushioning by introducing intermediate angular ratio values between different characteristic curves. These intermediate values act as a buffer or cushion during the transition, preventing abrupt changes in steering behavior and eliminating self-steering issues that would occur with direct switching between extreme ratio values.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Adaptability or versatility

If a mandatory zero crossing is required to switch between characteristic curves, then the angular ratio can be changed completely, but the steering operation becomes more complex and time-consuming

Engineering Contradiction:

Improvecharacteristic curve switching capabilityVSAvoidsteering wheel operation simplicity

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent applies segmentation by dividing the characteristic curve switching process into segments based on steering wheel position. The system determines whether the steering wheel is in a positive or negative angular position and selects appropriate intermediate angular ratio values accordingly. This segmentation allows complete characteristic curve switching without requiring the steering wheel to return to the zero position, simplifying the switching operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses temporary, position-dependent intermediate angular ratio values that are discarded after the switching transition is complete. These intermediate values exist only transiently during the switching process and are replaced by the target characteristic curve values, enabling flexible switching without permanent structural modifications or mandatory zero crossing requirements.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If the angular transmission ratio is adjusted to match a newly selected characteristic curve, then the steering response becomes accurate, but the adjustment process may cause abrupt changes in steering angle

Engineering Contradiction:

Improvesteering angle accuracyVSAvoidabrupt steering angle changes

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent applies dynamics by implementing a time-dependent adjustment of the angular transmission ratio. Instead of immediately setting the ratio to match the newly selected characteristic curve, the system evolves the ratio gradually over time from the old value to the new value, ensuring accurate final steering response while avoiding harmful abrupt changes during the transition.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements beforehand cushioning by introducing intermediate angular ratio values that buffer the transition between different characteristic curves. These intermediate values prevent direct, abrupt jumps in steering angle by providing a gradual transition path, thereby eliminating the harmful effects of sudden steering angle changes while still achieving accurate steering response.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentEP1857348B1Method for varying angle conversion depending on the characteristic curve or characteristic zone between the steering wheel and the wheel guide angle of the wheels used in steering a motor vehicle with an active steering system

Publication Date: 2011.04.27 AUDI AG

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Figure 4~5

AI summary

The method involves adjusting and setting an angle of a steering wheel (4) depending on a sensed motion of the steering wheel that is moved. The steering wheel is set in motion after choosing either a characteristic curve or characteristic field. The control/regulation of a set-up gear unit (6) is enabled by a control device (10) after a lapse of time, after choosing the characteristic curve or the field for a linear or step by step variation of the angle of conversion. An independent claim is also included for a motor vehicle comprising an active steering system with a control device.