Adaptive IMU Control Loops for Shock and Vibration Precision
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inertial measurement units (IMUs), particularly fiber optic gyroscopes, face challenges in maintaining accurate angular rate measurements under varying environmental conditions such as shock, vibration, and temperature changes due to design compromises that lead to saturation and errors in signal processing.
Innovation Solution
A control system with a processor that dynamically adjusts control loop set points based on environmental conditions, utilizing a dynamic loop adjuster to manage automatic gain control, phase modulator scale factor control, and offset control loops, ensuring optimal operation by altering gain allocation between analog and digital domains and slowing or opening auxiliary loops during disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the analog gain is set high to overcome A/D converter resolution limitations, then measurement precision is improved, but the maximum signal the A/D converter can handle is limited, causing saturation under high dynamics
Solution Approach 1:
The patent implements dynamic gain allocation where the analog gain is adjusted in real-time based on environmental conditions. During high dynamic events (vibration, shock), the analog gain is reduced to prevent A/D saturation, while during quiescent conditions, the analog gain is increased to maximize measurement precision. This dynamic adjustment resolves the contradiction between precision and reliability under different operating conditions.
Solution Approach 2:
The system changes the analog gain parameter dynamically based on detected environmental conditions. The gain allocation between analog and digital domains is adjusted as a variable parameter rather than being fixed, allowing the system to optimize for precision during low-dynamic conditions and prevent saturation during high-dynamic conditions.
2Measurement precision
If auxiliary control loops operate continuously to maintain optimal control points, then measurement accuracy is improved, but they respond to high dynamic signals and deviate from optimal control points, causing errors
Solution Approach 1:
The auxiliary control loops are operated periodically rather than continuously. The system detects high dynamic conditions and temporarily suspends or slows the auxiliary loops during vibration and shock events, then resumes normal operation when conditions return to quiescent states. This periodic operation prevents the loops from deviating during high dynamics while maintaining accuracy during normal operation.
Solution Approach 2:
The system detects environmental conditions in advance and preemptively adjusts auxiliary loop operation before high dynamic events can cause deviations. By monitoring for vibration and shock conditions, the system can suspend auxiliary loops proactively, preventing errors before they occur rather than correcting them after the fact.
3Adaptability or versatility
If the system is designed to operate through the full range of environments, then adaptability is improved, but design compromises are required that do not adequately address optimal operations over the range of environments
Solution Approach 1:
The system transitions from a static design with fixed gain and control parameters to a dynamic system that continuously adapts its parameters based on environmental conditions. By making gain allocation and auxiliary loop operation dynamic rather than fixed, the system can optimize for each specific operating condition rather than compromising for an average performance across all conditions.
Solution Approach 2:
The system uses environmental sensing and feedback mechanisms to detect current operating conditions and adjust control parameters accordingly. The feedback loop monitors for vibration, shock, and other environmental factors, then adjusts analog/digital gain allocation and auxiliary loop operation to maintain optimal performance across the full environmental range.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A control system includes a processor that operates one or more control loops that enable gyroscopic angular measurement for an inertial measurement unit (IMU). Each of the one or more control loops operates over a range of set points defined for each of the respective control loops. A dynamic loop adjuster receives environmental input data to determine environmental conditions for the IMU. The dynamic loop adjuster alters at least one of the set points for at least one of the one or more control loops operated by the processor based on the determined environmental conditions.