Vehicle LED Lighting With PWM Feedback for ASIL Fault Detection
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Solution Overview
Problem
Existing multicolor LED units in motor vehicles do not meet the required ASIL standard for safety-critical applications, such as autonomous driving, due to hardware faults in communication components and lack of bidirectional communication capability, which poses a risk in safety-relevant functions.
Innovation Solution
A lighting device with a processing module that converts data signals into pulse-width-modulated signals for LED units, enabling bidirectional communication and fault detection, allowing for monitoring of LED functionality and maintaining the ASIL standard through a system-in-package structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If LED units with integrated microcontrollers and ASIC-based function logic are used, then device integration and compactness are improved, but reliability and ASIL standard compliance deteriorate due to hardware faults and lack of fault detection capability
Solution Approach 1:
The patent implements bidirectional communication between the processing module and LED units, enabling the processing module to send activation information and receive status values. This feedback mechanism allows continuous monitoring of LED functionality and detection of hardware faults, ensuring ASIL standard compliance while maintaining integrated device structure.
Solution Approach 2:
The patent performs preliminary fault detection by establishing bidirectional communication capability that allows the processing module to query status values and detect hardware faults before they lead to safety-critical failures. This proactive monitoring ensures reliability without requiring complex ASIC-based logic.
2Reliability
If bidirectional communication capability is added to LED units, then fault detection and reliability are improved, but device complexity and communication infrastructure requirements worsen
Solution Approach 1:
The processing module serves multiple functions: it acts as both a control unit for activating LED units and a diagnostic unit for detecting hardware faults through bidirectional communication. This multi-functionality reduces the need for separate dedicated diagnostic hardware, thereby limiting the increase in overall device complexity.
Solution Approach 2:
The LED units transmit their own status values and functionality information back to the processing module, enabling self-diagnosis. This self-service approach reduces the complexity of external monitoring systems, as the LED units themselves provide the necessary diagnostic data without requiring additional sensors or monitoring hardware.
3Reliability
If statistical integrity proof is used for ASIC-based LED units, then ASIL standard can be achieved, but remaining risk from unknown random hardware faults persists
Solution Approach 1:
The bidirectional communication enables continuous feedback on LED unit status and functionality. This real-time monitoring allows the system to detect and respond to hardware faults as they occur, reducing the remaining risk from random hardware faults that statistical integrity proof alone cannot address.
Solution Approach 2:
The system performs preliminary detection of hardware faults through status value queries before these faults can lead to safety-critical failures. This proactive approach complements statistical integrity proof by providing actual runtime verification, thereby reducing the remaining risk from unknown random hardware faults.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures reliable operation by detecting hardware faults and maintaining the ASIL standard, enabling safe use in safety-critical applications like autonomous driving by ensuring correct signal conversion and communication between LED units and the processing module.
Implementation Method 1
LED units which are presently available have not been developed according to a safety level corresponding to ISO 26262
Implementation Method 2
drives the LED units, typically via PWM outputs (PWM='pulse width modulation')
Data Source
AI summary
A lighting device for a motor vehicle including a processing module which is configured to receive and process signals of a data bus of the motor vehicle and send a data signal. The lighting device also includes an LED unit configured to emit light, when operational, with an adjustable brightness and a predefined color location. The LED unit has a microcontroller and a plurality of LEDs, and the microcontroller and the plurality of LEDs are surrounded by a housing of the LED unit. Furthermore, the processing module is configured to convert the data signal, which contains control information for the LED unit, into a pulse width-modulated signal of the current supplied to the individual LEDs and to verify whether the pulse width-modulated signal contains information corresponding to the control information for the LED unit.