Autonomous Steering Thermal Derating Override

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Solution Overview

Problem

Autonomous vehicles face safety risks due to thermal derating of electronic power steering systems, which can limit torque without considering situational context, potentially leading to dangerous maneuvers in critical situations.

Innovation Solution

The autonomous driving control system takes over thermal derating functionality, allowing the vehicle to override derating limits during safety-critical maneuvers, such as avoiding objects or responding to faults, and distinguishes between manual and autonomous driving modes to manage temperature thresholds effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the steering system thermally derates to stay below temperature thresholds, then the steering system temperature is controlled, but the available torque is limited which may prevent safety-critical maneuvers

Engineering Contradiction:

Improvesteering system temperatureVSAvoidavailable torque

Core Design Contradiction:

TemperatureVSForce

Solution Approach 1:

The system dynamically adjusts thermal derating behavior based on driving mode. In autonomous mode, the system can override thermal derating limits when safety-critical maneuvers are detected, allowing torque to be prioritized over temperature control when necessary. This dynamic adjustment resolves the contradiction by making the torque limitation conditional rather than fixed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the operational parameters of thermal derating based on the detected driving mode and situational context. When autonomous driving mode is detected and a safety-critical maneuver is identified, the system modifies the torque limitation parameters to allow higher torque output despite temperature thresholds, effectively changing the derating behavior to prioritize safety.

Inventive Principle:

Principle #35Parameter changes

2Temperature

If the steering system limits torque due to thermal concerns, then the steering system temperature is managed, but the vehicle cannot perform necessary emergency avoidance maneuvers

Engineering Contradiction:

Improvesteering system temperatureVSAvoidsafety-critical maneuver capability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The system uses feedback from the autonomous driving control system to detect safety-critical situations and adjusts thermal derating behavior accordingly. When the autonomous system identifies an emergency avoidance maneuver as necessary, this feedback triggers the steering system to override thermal derating limits, ensuring the maneuver can be executed despite temperature concerns.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary detection of the autonomous driving mode and potential safety-critical situations before the maneuver is executed. By anticipating the need for emergency maneuvers through mode detection, the system can prepare to override thermal derating limits in advance, ensuring immediate torque availability when the maneuver becomes necessary.

Inventive Principle:

Principle #10Preliminary action

3Temperature

If the steering system applies thermal derating in autonomous mode, then temperature thresholds are maintained, but the autonomous driving control system loses ability to respond to emergencies

Engineering Contradiction:

Improvesteering system temperatureVSAvoidemergency response capability

Core Design Contradiction:

TemperatureVSEase of operation

Solution Approach 1:

The system merges the thermal management function with the autonomous driving control system's situational awareness. By combining temperature monitoring with emergency detection capabilities, the system can make integrated decisions that balance thermal constraints with safety requirements, allowing the autonomous system to override derating when emergencies are detected.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The autonomous driving control system acts as an intermediary between the thermal management system and the steering actuator. It receives temperature status information, evaluates situational context for safety-critical maneuvers, and mediates the final torque command to override thermal derating limits when necessary, preserving emergency response capability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11634160B2Thermal management of steering system for autonomous vehicles

Publication Date: 2023.04.25 WAYMO LLC

AI summary

Aspects of the disclosure relate to a vehicle having an autonomous driving mode and a manual driving mode. The vehicle may include a steering system having one or more processors configured to control the orientation of the one or more wheels based on control commands. The vehicle may also include an autonomous driving control system configured to control the vehicle in an autonomous driving mode by generating the control commands and to send the control commands to the steering system. In addition, the steering system may thermally derate the steering system based on first temperature information for the steering system when the vehicle is operating in a manual drive mode, and the autonomous driving control system may thermally derate the steering system based on second temperature information for the steering system when the vehicle is operating in the autonomous driving mode.