Weapon Arming System Logic Signal Mixing
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Solution Overview
Problem
Current missile arming systems have a single-point failure mode, where the failure of a single safety lock can result in premature arming or detonation, despite attempts to minimize this risk.
Innovation Solution
A pair of logic elements that output different types of signals, such as signals at different frequencies, are combined and processed to determine whether to trigger an arming switch, eliminating credible single-point failure modes by ensuring both signals are present before arming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple safety locks are used in sequence to control weapon arming, then the reliability against premature arming is improved, but the system eventually reaches a single-point failure condition where one remaining safety lock failure causes arming
Solution Approach 1:
The arming system is segmented into two independent logic elements that each process different types of events (launch events and flight events). This segmentation ensures that no single failure point can trigger arming, as both logic elements must independently satisfy their conditions and produce compatible signals before the weapon can arm.
Solution Approach 2:
A signal mixing circuit acts as an intermediary between the two logic elements and the arming switch. The mixer combines signals from both logic elements in an analog manner, requiring both signals to be present and compatible for the mixed output to trigger arming. This intermediary prevents direct digital logic failure propagation while maintaining safety.
2Reliability
If two independent logic elements output different types of signals, then single-point failure modes are eliminated, but the device complexity increases due to signal mixing requirements
Solution Approach 1:
The patent replaces complex digital logic combination circuits with an analog signal mixing approach. The mixer circuit combines different signal types (digital and analog, or different frequency signals) using analog addition, which is simpler and more reliable than designing complex digital logic to handle multiple signal types and failure modes.
Solution Approach 2:
The logic elements output signals with different characteristics (different frequencies, different signal types) rather than identical digital signals. This parameter differentiation allows the mixer to naturally distinguish between valid combined signals and failure conditions, simplifying the overall system design while maintaining high reliability.
Data Source
AI summary
An arming system for a weapon, such as a missile, includes a pair of logic elements that output different types of signals upon the occurrence of different pre-arming events. The different types of signals may be, for instance, signals at different frequencies. The different signals are combined in a mixer. The mixed combined signal may be processed by passing it though elements such as a band pass filter and/or a pulse-width modulator/controller. An arming switch is configured to initiate arming when a predetermined condition in the combined signal is detected, such as the presence of a frequency in the combined signal at the difference between the frequencies of the individual signals from the logic elements. By basing arming on characteristics of a mixed combined signal from two logical elements, there are no credible single-point failure modes in the arming system.