Steering Gearbox Feedback Control for Critically Damped Vehicle Steering

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Solution Overview

Problem

Autonomous vehicles experience oscillations and weaving due to underdamped steering control systems, posing safety risks, especially in long vehicle-trailer combinations, as existing control loops fail to provide sufficient damping forces to stabilize vehicle direction.

Innovation Solution

Implement a steering gear box with a final steering control system that integrates critically damped control loops and a self-tuning algorithm, using sensors to adapt to external forces and generate a combined critically damped output to control wheel angles, reducing oscillations through a PID loop configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional steering control loops are used, then the steering system is simple to implement, but the vehicle experiences oscillations and weaving due to underdamping

Engineering Contradiction:

Improvevehicle stabilityVSAvoidcontrol system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a feedback control system where the final steering control system receives feedback from multiple control loops (lateral control, longitudinal control, driver input) and generates a critically damped output signal. This feedback mechanism allows the system to continuously adjust steering commands to eliminate oscillations and maintain vehicle stability, directly resolving the contradiction between simplicity and stability.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the damping parameter of the steering control system from underdamped (conventional) to critically damped. By adjusting the control algorithm parameters in the final steering control system, the system achieves optimal damping without requiring complex hardware modifications, thus improving stability while maintaining relative simplicity.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If multiple control loops are cascaded to the final steering control system, then comprehensive control inputs are achieved, but the damping forces are insufficient to minimize vehicle oscillations

Engineering Contradiction:

Improvecontrol input integrationVSAvoidoscillation control

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent merges multiple control loops (lateral control, longitudinal control, driver steering input) into a single final steering control system. By combining these control inputs and processing them through a unified critically damped control algorithm, the system achieves both comprehensive adaptability to various control inputs and sufficient damping forces to eliminate oscillations.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent modifies the damping parameter of the cascaded control loops by implementing a critically damped response in the final steering control system. This parameter change ensures that the combined control inputs from multiple loops produce sufficient damping forces, resolving the contradiction between versatility and oscillation control.

Inventive Principle:

Principle #35Parameter changes

3Speed

If the vehicle direction is adjusted abruptly to compensate for external factors, then the vehicle responds quickly to road conditions, but the long vehicle-trailer combination becomes unstable and weaves

Engineering Contradiction:

Improveresponse speedVSAvoidvehicle alignment stability

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary anti-action by implementing a critically damped control algorithm that anticipates and counteracts potential oscillations before they occur. When the vehicle direction needs to be adjusted, the system pre-applies damping forces to prevent instability, allowing quick response to road conditions while maintaining alignment stability of the long vehicle-trailer combination.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent changes the damping parameter from underdamped to critically damped, which optimizes the balance between response speed and stability. This parameter change allows the vehicle to respond quickly to external factors while the critical damping prevents the amplification of oscillations that would occur with abrupt direction adjustments.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12485958B2Feedback control system and steering gear box for final steering control of an autonomous vehicle

Publication Date: 2025.12.02 TORC ROBOTICS INC

AI summary

A steering control system and method of controlling a vehicle using the steering control system are disclosed. The final steering control system is configured to receive a plurality of critically damped outputs generated by a plurality of critically damped control loops, and generate, based on the plurality of critically damped outputs, a combined critically damped output. A steering gear box is communicatively coupled with a final steering control system and configured to receive the combined critically damped output from the final steering control system to control a steering angle of a vehicle based on the combined critically damped output.