Steer-by-Wire Reaction Force Control for Steering Response Delay

Solution Overview

Problem

In steer-by-wire steering apparatuses, response delays in steering unit response to driver input can lead to a mismatch between vehicle behavior and driver expectation, causing excessive or insufficient steering reaction forces.

Innovation Solution

A control unit with a reaction force actuator control section, a steering actuator control section, a deviation recognition section, and a reaction force actuator output boost section that adjusts the steering reaction force based on the deviation between the steering input and the actual steering angle, thereby compensating for response delays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the steering reaction force is controlled based on a response delay inferred from the operation amount of a steering actuator, then the steering reaction force can be adjusted to reduce response delay, but the steering reaction force may be excessive or deficient because the response delay varies depending on conditions such as the state of the road

Engineering Contradiction:

Improveresponse delay in steering amountVSAvoidaccuracy of steering reaction force control

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The system uses feedback control by continuously monitoring the deviation between the manipulated steering angle and the actual steering angle, and adjusting the steering reaction force based on this real-time deviation information. This ensures accurate and reliable control adaptation to varying road conditions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces the conventional mechanical inference method (estimating response delay from steering actuator operation amount) with an electrical/electronic measurement method (directly measuring the actual steering angle using a steering angle sensor). This substitution provides more accurate and reliable data for control decisions.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Speed

If the steering reaction force is increased to curb the manipulation speed of the steering operation input member, then the response delay in steering amount can be reduced, but the steering reaction force may become excessive when the delay is actually small

Engineering Contradiction:

Improveresponse speed of steering unitVSAvoidsteering reaction force

Core Design Contradiction:

SpeedVSForce

Solution Approach 1:

The system dynamically adjusts the steering reaction force based on the real-time measured deviation between manipulated steering angle and actual steering angle. The reaction force increases only when the deviation exceeds a threshold, and adjusts proportionally to the deviation magnitude, providing dynamic and adaptive control rather than fixed force application.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the control parameter from a fixed or inferred response delay value to a dynamically measured deviation value. By using the actual steering angle sensor data, the system adapts the steering reaction force parameter according to the real-time state of the steering system and road conditions.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If the steering reaction force is decreased to avoid excessive force, then the driver's perception of vehicle behavior matches expectation better, but the response delay in steering amount increases

Engineering Contradiction:

Improvedriver perception of vehicle behaviorVSAvoidresponse delay in steering amount

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The system dynamically adjusts the steering reaction force based on the real-time measured deviation between manipulated steering angle and actual steering angle. The reaction force increases only when the deviation exceeds a threshold, and adjusts proportionally to the deviation magnitude, providing dynamic and adaptive control rather than fixed force application.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses feedback control by continuously monitoring the deviation between the manipulated steering angle and the actual steering angle, and adjusting the steering reaction force based on this real-time deviation information. This ensures accurate and reliable control adaptation to varying road conditions.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12330725B2Steer-by-wire steering apparatus

Publication Date: 2025.06.17 ASTEMO LTD

AI summary

A steer-by-wire steering apparatus according to the present invention includes: a reaction force actuator control section that controls an output amount of a reaction force actuator; a steering actuator control section that controls a steering actuator in response to a manipulation of a steering operation input member, the steering actuator steering steered wheels via a steering unit; a deviation recognition section that recognizes a deviation between a manipulation amount of the steering operation input member and a steering amount of the steering unit; and a reaction force actuator output boost section that, when the deviation increases, increases the output amount of the reaction force actuator. Thus, the steering reaction force can be appropriately controlled in correspondence with a response delay in the steering amount of the steering unit with respect to the manipulation amount of the steering operation input member.