Self-testing Ultrasonic Sensor System for Automotive Functional Safety
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Solution Overview
Problem
Ultrasonic sensor systems in the automotive sector face challenges in detecting hidden errors, particularly for autonomous functions like automatic parking, due to the need for high functional safety standards as per ISO 26262, and existing self-diagnosis methods are not comprehensive or efficient.
Innovation Solution
A self-testable ultrasonic sensor measuring system and method that includes various diagnostic tests such as checking digital signal processing, impedance, symmetry, and harmonic checks, using a digital signal generation unit, driver stage, measurement unit, analog and digital front-end circuits, and channel simulation units to simulate and test signal paths, ensuring precise and quick self-testing during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If comprehensive self-diagnosis capability is implemented to detect hidden errors, then reliability is improved, but device complexity increases
Solution Approach 1:
The measuring system performs self-testing by generating test signals internally and evaluating its own response. The control device activates test signal generation units that inject test signals into the signal paths, and the system evaluates the responses to detect errors in transducers, signal paths, and processing circuits without external intervention.
Solution Approach 2:
Test signal generation units and evaluation units are introduced as intermediary components between the existing signal generation and processing paths. These intermediaries inject test signals at specific points and capture responses, enabling comprehensive testing without fundamentally redesigning the entire system architecture.
2Measurement precision
If multiple test states and comprehensive testing is performed, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The system implements three distinct test states (first, second, and third test states) that periodically cycle through different testing scenarios. Each test state focuses on specific aspects of the system, allowing comprehensive coverage while organizing the testing process into manageable periodic intervals rather than continuous exhaustive testing.
Solution Approach 2:
The comprehensive testing is divided into three separate test states, each targeting specific components and signal paths. The first test state evaluates basic functionality, the second test state tests signal paths with simulated responses, and the third test state validates processing circuits. This segmentation allows parallel execution of different test aspects and reduces overall testing time.
3Reliability
If test signals are injected at multiple points in the signal path, then reliability is improved, but device complexity increases
Solution Approach 1:
The test signal generation units are designed to be multi-functional, capable of generating different types of test signals and injecting them at multiple points in the signal path. The same hardware units can test transducers, signal paths, and processing circuits by changing the injection point and signal characteristics, rather than requiring separate dedicated test equipment for each function.
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
The system achieves a high level of functional test coverage during normal operation, allowing for efficient detection of errors and operation-relevant disturbances, enhancing the reliability of ultrasonic sensor systems in automotive applications.
Implementation Method 1
a measurement unit (TR) for converting the power-amplified stimuli into measurement signals in the measurement medium (e.g. air in the case of ultrasound) and for receiving the channel response from the measuring channel (CH) in the form of a received signal
Data Source
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AI summary
The invention relates to a self-testing measuring system (SS) which can have at least three modes, an operating mode and at least two test modes. In a third test mode, a digital signal producing unit (DSO) stimulates the digital input circuit (DSI) directly by means of test signals, thereby allowing this signal string to be tested. In a second test mode, the digital signal producing unit (DSO) stimulates the analogous signal string (DR, AS) and the digital input circuit (DSI) by means of test signals, thereby allowing this signal string to be tested. In a first test mode, the digital signal producing unit (DSO) stimulates the analogous signal string (DR, AS), the measuring unit (TR) (typically an ultrasound transducer) and the digital input circuit (DSI) by means of test signals, thereby allowing this signal string to be tested and being monitored for parameter compliance, in particular signal amplitudes. In the operating mode, the digital signal producing unit (DSO) stimulates the analogous signal string (DR, AS), the measuring unit (TR) (typically an ultrasound transducer) and the digital input circuit (DSI) by means of output signals, thereby allowing the signal string to be monitored for parameter compliance, in particular signal amplitudes.