Vehicle Power Management Ignition Failure Handling
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Solution Overview
Problem
Vehicle subsystems may inadvertently turn off when the ignition system fails or is turned off inadvertently while the vehicle is moving, leading to unintended disabling of functionality.
Innovation Solution
A processing device is programmed to determine the ignition state and vehicle speed, powering certain subsystems if the ignition is off but the vehicle is moving above a predetermined speed, and disabling them when the speed falls below this threshold, with optional situational overrides for specific scenarios like towing or parking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the ignition system is turned off to save energy, then power consumption is reduced, but vehicle subsystems may be inadvertently disabled while the vehicle is moving
Solution Approach 1:
The power management system dynamically adjusts subsystem power states based on real-time vehicle operating conditions. The processing device continuously monitors vehicle speed and ignition state, and automatically transitions subsystems between powered and unpowered states based on predefined criteria (e.g., maintaining power above threshold speed even when ignition is off). This dynamic adaptation resolves the contradiction by making power management flexible rather than static.
Solution Approach 2:
The system implements feedback control by continuously monitoring vehicle speed and ignition state, then using this information to determine whether to maintain or disable subsystem power. The processing device receives feedback about current operating conditions and adjusts power delivery accordingly, ensuring subsystems remain powered when the vehicle is moving while allowing power savings when the vehicle is stationary.
2Device complexity
If the ignition state is used to control subsystem power, then power management is simplified, but subsystems cannot distinguish between intentional shutdown and ignition failure
Solution Approach 1:
The processing device acts as an intermediary layer between the ignition system and vehicle subsystems. Instead of directly connecting ignition state to subsystem power, the processing device receives ignition state signals and uses additional criteria (vehicle speed, override inputs) to determine actual power delivery. This intermediary function adds intelligence to the power management system, allowing it to distinguish between intentional shutdowns and ignition failures while maintaining reasonable system complexity.
3Reliability
If subsystems remain powered during ignition off-state to prevent failure, then subsystem reliability is improved, but energy consumption increases
Solution Approach 1:
The system changes the parameter of power delivery based on operating conditions. The processing device adjusts whether subsystems receive power by evaluating multiple parameters including vehicle speed, ignition state, and override inputs. Subsystems receive continuous power when vehicle speed exceeds a threshold during ignition off-state, but transition to unpowered state when speed drops below the threshold, optimizing the balance between reliability and energy consumption.
Data Source
AI summary
A vehicle system includes a processing device programmed to determine an ignition state and a vehicle speed. The processing device powers at least one vehicle subsystem if the ignition state is off and the vehicle speed is above a predetermined threshold. The processing device may disable the vehicle subsystem when the vehicle speed falls below the predetermined threshold.