Steering Control Apparatus Using Transverse-G Allocation

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Solution Overview

Problem

The existing steer-by-wire steering control apparatuses require expensive axial force sensors to generate steering reaction forces, leading to increased manufacturing costs.

Innovation Solution

The system allocates current axial force and transverse-G axial force at predetermined ratios to calculate a feedback axial force, which is used to drive a reaction force motor, eliminating the need for dedicated axial force sensors by compensating for phase delays and reflecting road surface disturbances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an axial force sensor is used to generate steering reaction force, then the steering reaction force accurately reflects the rack axial force, but the manufacturing cost increases due to the expensive sensor

Engineering Contradiction:

Improvesteering reaction force accuracyVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent creates a calculated copy of the rack axial force by allocating components from transverse acceleration and steering angle measurements. Instead of directly measuring the axial force with an expensive sensor, the system computes an equivalent value through mathematical allocation, where the transverse acceleration sensor data is processed to reproduce the axial force information that would otherwise require direct sensing.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical/physical measurement system (axial force sensor) with a computational system. By substituting the direct physical sensing approach with mathematical calculation based on transverse acceleration and steering angle, the system eliminates the need for the expensive axial force sensor while maintaining the functional equivalence of steering reaction force generation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If transverse acceleration is used to calculate axial force, then the measurement can be obtained without additional sensors, but phase delay occurs reducing the accuracy

Engineering Contradiction:

Improvesensor costVSAvoidaxial force measurement accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by allocating a lead component from the transverse acceleration signal to compensate for the inherent phase delay. The calculation system预先 (in advance) adjusts the timing and magnitude of the acceleration component contribution to counteract the delay that would naturally occur, ensuring that the calculated axial force remains synchronized with the actual mechanical state.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent incorporates feedback mechanisms where the allocated components from transverse acceleration are continuously adjusted based on the relationship with steering angle and the required steering reaction force. The system uses feedback to optimize the allocation ratio, ensuring that the calculated axial force accurately reflects the actual conditions while maintaining cost-effectiveness.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9701337B2Steering control apparatus and steering control method

Publication Date: 2017.07.11 NISSAN MOTOR CO LTD

AI summary

A control computing unit allocates the current axial force and the transverse-G axial force at the predetermined allocation ratio to calculate a feedback axial force which is the steering-rack axial force. Then, the control computing unit drives the reaction force motor on the basis of the calculated feedback axial force. Additionally, the allocation ratio of the transverse-G axial force is set to be greater than the allocation ratio of the current axial force.