Projectile Velocity Measurement via Spin Rate Detection
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Solution Overview
Problem
Guided projectiles face range errors due to variations in launch velocity caused by factors like explosive charge, temperature, and wind, leading to inaccuracies in targeting.
Innovation Solution
A precision guidance munition assembly that measures the spin rate of the projectile shortly after launch using a hall effect sensor and magnet combination, allowing for early correction of the trajectory by adjusting canards to ensure accurate targeting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If velocity measurement is delayed until later in flight, then there is more time for the sensor to stabilize, but the time available for trajectory correction is reduced
Solution Approach 1:
The patent measures spin rate immediately after launch using a sensor mounted on the stabilizing fins that are already rotating with the projectile. This preliminary measurement approach captures velocity data before significant trajectory deviation occurs, enabling earlier correction actions while the projectile is still in the可控 flight phase.
Solution Approach 2:
The patent uses the stabilizing fins as an intermediary element to mount the velocity measurement sensor. The fins naturally rotate with the projectile due to rifling spin, providing a stable platform for the sensor without requiring additional complex mounting mechanisms. This intermediary approach enables early measurement while maintaining measurement reliability.
2Stability of the object's composition
If the projectile is given high spin rate for stability, then flight stability is improved, but the Rifling-induced velocity measurement error increases
Solution Approach 1:
The patent introduces the stabilizing fins as an intermediary carrier for the velocity measurement sensor. These fins rotate at a different rate than the main projectile body, effectively decoupling the measurement system from the high-spin projectile. This intermediary approach allows accurate velocity measurement while preserving the high spin rate needed for flight stability.
Solution Approach 2:
The patent changes the rotational parameter of the measurement platform by mounting the sensor on the stabilizing fins rather than the projectile body. The fins rotate at a lower, more manageable rate that reduces centrifugal forces and measurement errors while still maintaining the high spin rate of the projectile for stability. This parameter change enables both high stability and accurate measurement.
3Device complexity
If the sensor is mounted on the rotating projectile body, then the measurement system is simplified, but the measurement accuracy is reduced due to centrifugal forces and vibration
Solution Approach 1:
The patent uses the stabilizing fins as an intermediary mounting platform that experiences less severe centrifugal forces and vibration than the projectile body. The fins are located at the rear of the projectile and have a smaller radius of rotation, providing a more stable measurement environment while still rotating with the projectile. This intermediary approach balances simplicity with measurement accuracy.
4Adaptability or versatility
If the canard assembly is used for trajectory correction, then the range control authority is improved, but the device complexity increases
Solution Approach 1:
The patent employs the existing canard assembly, originally designed for flight control and stabilization, to also perform trajectory correction for range adjustment. By repurposing this existing component for dual functions, the system gains enhanced adaptability without proportionally increasing complexity. The canards self-adjust based on feedback from the velocity measurement to correct trajectory deviations.
Solution Approach 2:
The patent makes the canard assembly multi-functional by using it both for primary flight control and for trajectory correction during the mid-flight phase. This universal use of the canard system allows the projectile to compensate for velocity variations and adjust range without adding dedicated correction mechanisms, thereby improving adaptability while limiting complexity growth.
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 provides more range control authority and reduces targeting errors by enabling early velocity measurement and correction, improving the projectile's ability to hit intended targets.
Implementation Method 1
the sensor is a hall effect sensor that is carried by the precision guidance munition assembly that cooperates with a small magnet carried by the body
Data Source
AI summary
A sensor determines the spin rate or rotation frequency of a munition body of a guided projectile relative to precision guidance munition assembly. The spin rate is used to determine launch velocity of the guided projectile early in flight before GPS is operationally active. The launch velocity is used to determine whether a corrective maneuver is needed to change the range of the guided projectile. Logic can control the canards on the canard assembly in response to the determination that a corrective maneuver is needed.