Squib Loop Resistance Measurement Using Dual Bias Currents
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Solution Overview
Problem
Current methods for diagnostic testing of squib loop resistance in advanced airbag systems with non-linear components are inadequate, leading to diminished accuracy and safety feedback in complex duplex systems, which are larger, heavier, and more complex than single-stage systems.
Innovation Solution
A method and system that accurately measures linear resistance in squib loop circuits with non-linear components by applying a single or dual bias current to calculate the diode resistance and total squib loop resistance, allowing for reliable diagnostic testing and storage of nominal resistances in memory for comparison.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If dual stage systems combine multiple squib loops into a single wiring squib loop path, then packaging size and weight are reduced, but measurement precision of linear resistance deteriorates due to non-linear components
Solution Approach 1:
The patent segments the total resistance measurement into two distinct components: linear resistance (R_linear) and non-linear resistance (R_nonlinear). By applying different bias currents and measuring corresponding voltage differentials, the system separates these resistance types mathematically, allowing accurate measurement of linear resistance even in the presence of non-linear components like diodes.
Solution Approach 2:
The patent changes the parameter of bias current magnitude to differentiate between linear and non-linear resistance measurements. By using a first bias current level for total resistance measurement and a second bias current level for non-linear resistance measurement, the system exploits the different electrical characteristics of linear and non-linear components under varying current conditions.
2Device complexity
If dual stage systems combine multiple squib loops into a single wiring squib loop path, then system complexity is reduced, but measurement precision of linear resistance deteriorates
Solution Approach 1:
The measurement process is segmented into distinct phases: first measuring total resistance at one bias current level, then measuring non-linear resistance at another bias current level. This segmentation allows the system to extract linear resistance information from a complex circuit containing both linear and non-linear components without requiring physical separation of the components.
Solution Approach 2:
The patent introduces mathematical calculation as an intermediary process between the physical measurement and the final linear resistance value. By using equations that relate the measured voltage differentials at different bias currents to the respective resistance components, the system bridges the gap between the complex physical circuit and the desired linear resistance measurement.
3Ease of manufacture
If traditional resistance measurement methods are used in systems with non-linear components, then ease of manufacture is maintained, but measurement precision of linear resistance deteriorates
Solution Approach 1:
The system uses its own control module and existing wiring infrastructure to perform the resistance measurements. By leveraging the existing power supply capabilities of the control module to provide the necessary bias currents, the system achieves accurate linear resistance measurement without requiring external specialized equipment or complex manufacturing modifications.
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
This approach enables accurate and reliable diagnostic measurement of linear resistance in duplex systems, reducing material and cost while maintaining safety standards, and improving the efficiency and accuracy of airbag system diagnostics.
Implementation Method 1
measuring a first total resistance of the squib loop at a first bias current level
Implementation Method 2
measuring a first voltage differential across the non-linear component when a first bias current is applied thereto
Data Source
AI summary
A method of measuring squib loop resistance including non-linear elements in a restraint control module is disclosed by the present invention. The squib loop resistance is comprised of both linear and non-linear elements. The non-linear elements are linearized into resistive components about the bias points used to make the squib loop resistance measurement. The calculation of the linear squib loop resistance is provided by comparing the complete squib loop resistance and the linearized value of the non-linear elements.