Sealed Apogee Detection Module Without Barometric Dependence
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Solution Overview
Problem
Existing apogee detection systems for ballistic projectiles are unreliable due to their reliance on external environmental data, are computationally inefficient, and are not capable of predicting apogee accurately, leading to potential mission failures.
Innovation Solution
A self-contained apogee detection system using a combination of sensors such as accelerometers, gyroscopes, and magnetometers, processed by a quaternion extended Kalman filter, which predicts and detects apogee without relying on barometric pressure or a priori knowledge, allowing for real-time computation and minimal size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional mechanical or barometric apogee detection systems are used, then the system structure is simple, but the detection accuracy and reliability are insufficient
Solution Approach 1:
The patent combines multiple sensors (accelerometer, gyroscope, magnetometer) into an integrated detection system that uses sensor fusion algorithms to achieve high-precision apogee detection. This merging of multiple sensing modalities resolves the contradiction by improving measurement precision through complementary data while managing device complexity through unified processing architecture.
Solution Approach 2:
The patent replaces traditional mechanical apogee detection mechanisms with an electronic sensor-based system using inertial measurement units and magnetic field sensing. This substitution eliminates mechanical wear and failure modes while achieving superior detection accuracy through electronic signal processing and quaternion-based attitude determination.
2Reliability
If apogee detection systems rely on external environmental data, then the system can function with basic sensors, but the reliability is compromised under varying environmental conditions
Solution Approach 1:
The patent implements a self-contained detection system that determines apogee using only onboard sensors and internal processing. The system uses the projectile's own inertial data and magnetic field measurements to calculate attitude and detect apogee without requiring external barometric pressure data or environmental references, thereby achieving reliability independent of varying environmental conditions.
Solution Approach 2:
The patent transforms the detection approach by changing from environmental parameter-based detection (barometric pressure) to inertial parameter-based detection (acceleration, angular velocity, magnetic field). This parameter change enables the system to maintain reliability across diverse environmental conditions by relying on intrinsic projectile dynamics rather than external environmental references.
3Measurement precision
If complex sensor fusion algorithms are used to improve detection accuracy, then the measurement precision increases, but the computational efficiency decreases
Solution Approach 1:
The patent pre-calculates and stores quaternion rotation matrices and sensor fusion transformation coefficients during system initialization or offline processing. By preparing these computational elements in advance, the system reduces real-time computational burden during flight, allowing complex sensor fusion algorithms to execute efficiently on embedded processors without compromising measurement precision.
4Weight of moving object
If the apogee detection system is made compact to reduce size and weight, then the projectile performance improves, but the sensor integration and processing capability are constrained
Solution Approach 1:
The patent integrates the apogee detection system as a nested module within the projectile's existing guidance, navigation, and control (GNC) architecture. The detection electronics are housed within the projectile body, with sensors mounted on available structural platforms and processing shared with other onboard systems. This nesting approach minimizes additional weight and space while managing integration complexity through modular design.
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 provides accurate and timely detection and prediction of apogee, enabling precise triggering of mission-critical events like fuze arming, propulsion ignition, and control surface deployment, enhancing the accuracy and range of projectile trajectories.
Implementation Method 1
The circuit includes a three-axis accelerometer
Implementation Method 2
The circuit includes a three-axis magnetometer
Implementation Method 3
The circuit includes a three-axis gyroscope
Implementation Method 4
processed by a quaternion extended Kalman filter
Data Source
AI summary
A closed, self-contained ballistic apogee detection module for use in a projectile, such as a rocket, mortar round, or artillery round, fuses data from multiple built-in sensors, such as an accelerometer, a magnetometer, and a gyroscope, and processes the data using a microprocessor through a custom quaternion extended Kalman filter to provide accurate state and orientation information about the projectile so as to accurately predict apogee. The module outputs a signal indicating apogee detection or prediction which they projectile uses to initiate fuze arming, targeting control, airbody transformation, maneuvering, flow effector deployment or activation, payload exposure or deployment, and/or other mission activity. Because the system and method of the invention does not rely on external environmental data to detect apogee, it need not use a pressure sensor and can be completely sealed in and closed without requiring access to air from outside the projectile for barometric readings.