Micro-Thruster Response Time Measurement Using Digital Filter Compensation
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Solution Overview
Problem
Current methods for measuring thrust response time of satellite-borne micro-thrusters face challenges due to low natural frequency of thrust measurement systems, which makes it difficult to accurately measure rapid-varying thrust, especially when the response time is in the 10-ms level, and existing dynamic thrust computation methods are immature and prone to errors.
Innovation Solution
A digital filter-based method is introduced to increase the natural frequency of the thrust measurement system by connecting a digital filter in series, allowing for the measurement of thrust response time by determining system responses and adjusting vibration frequency and damping ratio to accurately compute thrust increasing and decreasing times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the natural frequency of the thrust measurement system is increased to measure rapid-varying thrust, then the measurement precision of thrust response time is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent replaces the mechanical approach of increasing physical natural frequency with a digital signal processing approach. A digital filter is designed with specific poles and zeros to create a virtual high-frequency measurement system, allowing accurate measurement of thrust response time without modifying the physical measurement system's mechanical properties.
Solution Approach 2:
The patent changes the parameters of the measurement system by introducing digital filter parameters (pole locations, zero locations, filter coefficients) instead of changing physical parameters like stiffness or mass. This allows the system to achieve high-frequency measurement capability through parameter configuration rather than physical modification.
2Measurement precision
If the stiffness coefficient is decreased to increase sensitivity for micro-thrust measurement, then the measurement precision of micro-thrust is improved, but the natural frequency decreases making rapid response measurement difficult
Solution Approach 1:
The patent substitutes the mechanical relationship between stiffness and natural frequency with a digital filter relationship. The filter's pole-zero configuration creates an equivalent high-frequency system that decouples the sensitivity-stiffness relationship from the natural frequency limitation, allowing low stiffness (high sensitivity) to coexist with high measurement bandwidth.
3Speed
If the moment of inertia of rotary components is decreased to increase natural frequency, then the measurement capability for rapid-varying thrust is improved, but the system becomes more difficult to manufacture and assemble
Solution Approach 1:
The patent replaces mechanical modifications (changing moment of inertia) with digital signal processing. The measurement system processes signals through a digital filter that creates a virtual high-frequency response, eliminating the need to physically reduce component moments of inertia and avoiding associated manufacturing and assembly challenges.
4Measurement precision
If a digital filter is introduced to increase natural frequency, then the measurement precision of thrust response time is improved, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical modifications with a relatively simple digital filter implementation. The filter uses standard digital signal processing techniques with configurable poles and zeros, which can be implemented in software or firmware without adding significant hardware complexity to the measurement system.
Data Source
AI summary
The present disclosure belongs to the technical field of space satellite propulsion, and particularly relates to a digital filter based method for measuring thrust response time of a satellite-borne micro-thruster. The method for measuring thrust response time in the present disclosure includes the following steps: S1: zeroing non-zero initial conditions of a torsional pendulum thrust measurement system to obtain an oscillating differential equation for a thrust measurement system after variable substitution; S2: connecting the digital filter in series behind the thrust measurement system after variable substitution to obtain an equivalent-sensitivity high-frequency thrust measurement system; S3: determining a system response of the equivalent-sensitivity high-frequency thrust measurement system; S4: determining and reading thrust response time of the satellite-borne micro-thruster from the system response; and S5: computing thrust to be measured by means of the system response inversely, and further confirming the thrust response time.