Projectile Control Using Doppler Positioning Without GNSS
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Solution Overview
Problem
Current methods for controlling projectiles, such as steerable munitions and air-burst projectiles, face challenges due to reliance on Global Navigation Satellite Systems (GNSS) which are prone to interference and accuracy issues, and electro-mechanical sensors that struggle with precise rotational frequency measurement.
Innovation Solution
A control system utilizing a plurality of transmitters that transmit electromagnetic waves, allowing a receiver on the projectile to determine its position, velocity, or acceleration through Doppler measurements, enabling robust and accurate control signals for trajectory adjustment or fuze activation, independent of GNSS when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GNSS receiver is used for navigation, then positioning capability is provided, but reliability and accuracy deteriorate due to spoofing and interference
Solution Approach 1:
The patent introduces an intermediary measurement system (Doppler shift measurement of electromagnetic waves from ground transmitters) that mediates between the unreliable GNSS signals and the navigation requirement. This intermediary method provides a alternative measurement path that is not susceptible to GNSS spoofing and interference, thereby improving reliability while maintaining positioning accuracy.
Solution Approach 2:
The patent replaces the electronic/GNSS-based navigation system with a physics-based Doppler measurement system. By substituting the electronic signal processing approach with physical measurement of electromagnetic wave frequency shifts, the system achieves immunity to electronic spoofing and interference, resolving the reliability-accuracy contradiction.
2Measurement precision
If electro-mechanical sensors are used for rotational frequency measurement, then rotational rate is detected, but measurement precision deteriorates
Solution Approach 1:
The patent replaces electro-mechanical rotational sensors with an optical/electromagnetic measurement system that uses Doppler shift analysis. This substitution eliminates the mechanical components that limit measurement precision while providing a non-contact, high-precision method for determining rotational frequency through electromagnetic wave analysis.
3Ease of operation
If GNSS receiver antennas are placed on spinning projectile, then positioning function is enabled, but signal quality and availability deteriorate
Solution Approach 1:
The patent introduces ground-based electromagnetic wave transmitters as an intermediary system that eliminates the need for GNSS antennas on the spinning projectile. By measuring Doppler shifts of waves from stationary ground transmitters, the system provides positioning functionality without the signal quality degradation caused by projectile rotation.
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 solution provides resilient and accurate control of projectiles by determining their state using Doppler measurements, overcoming GNSS vulnerabilities and improving the precision of air-burst timing and trajectory adjustments.
Implementation Method 1
determine at least one of a position, a velocity or an acceleration of the projectile from transmission positions of the plurality of transmitters and Doppler measurements derived from the received plurality of electromagnetic waves
Data Source
AI summary
According to an aspect of the invention, there is provided a control system for controlling a projectile, the control system comprising: a plurality of transmitters, wherein each transmitter of the plurality of transmitters is arranged to transmit an electromagnetic wave from a transmission position; a receiver associated with the projectile, the receiver being arranged to receive a plurality of electromagnetic waves transmitted from the plurality of transmitters; a controller associated with the projectile, the controller being arranged to: determine at least one of a position, a velocity or an acceleration of the projectile from transmission positions of the plurality of transmitters and Doppler measurements derived from the received plurality of electromagnetic waves; and generate a control signal for performing an action with the projectile depending on the determined at least one of position, velocity or acceleration of the projectile.