Adaptive X-Ray Tube Control for Transient Response
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Solution Overview
Problem
Existing radiological equipment with X-ray tubes faces challenges in controlling anode voltage and filament voltage for short-term exposures due to the dynamic nature of each tube, which is affected by degradation and thermodynamic conditions, leading to inadequate control for transient processes.
Innovation Solution
An adaptive control system is implemented, using a Model Reference Adaptive Control (MRAC) method with time-varying control laws for both anode and filament voltages, adjusted by 'learning rate' parameters to optimize anode current, enhancing responsiveness and accuracy during exposures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional control methods with constant anode voltage and table-based filament voltage control are used, then the control system is simple to implement, but the transient response time is too slow (400-600 ms) for short-term exposures (10-100 ms)
Solution Approach 1:
The patent applies dynamics by transitioning from static, table-based voltage control to dynamic, real-time control. The control system continuously adjusts filament voltage based on measured anode current feedback during the exposure, enabling the system to adapt to transient conditions and achieve fast response times (10-100 ms) while maintaining accuracy despite tube degradation and thermodynamic variations.
Solution Approach 2:
The patent implements feedback control by measuring the actual anode current during exposure and using this measurement to adjust the filament voltage in real-time. This closed-loop feedback mechanism allows the system to compensate for tube dynamics, degradation, and thermodynamic conditions, achieving precise control with fast transient response without requiring overly complex open-loop control schemes.
2Stability of the object's composition
If the control system attempts to keep anode current constant by adjusting filament voltage, then the anode current stability improves, but the control becomes critical and ineffective for short-term exposures due to the slow effect (400-600 ms)
Solution Approach 1:
The patent resolves this contradiction by implementing real-time feedback control where the anode current is measured during the exposure and used to adjust the filament voltage dynamically. This allows the system to maintain anode current stability while responding within the required 10-100 ms exposure window, overcoming the 400-600 ms delay of conventional methods.
Solution Approach 2:
The patent applies dynamics by making the control system adaptive and time-varying. Instead of using fixed table-based voltage values, the system continuously adjusts voltages based on real-time measurements and tube conditions, enabling both current stability and fast response for short-term exposures.
3Ease of manufacture
If standard control tables are used for filament voltage selection, then the control method is easy to implement, but it does not account for tube degradation, thermodynamic conditions, or individual tube dynamics
Solution Approach 1:
The patent maintains ease of implementation through automated feedback control while significantly improving adaptability. The system automatically measures anode current and adjusts filament voltage based on real-time conditions, eliminating the need for manual table lookups and adapting to tube degradation, thermodynamic conditions, and individual tube characteristics without requiring complex manual calibration procedures.
Solution Approach 2:
The patent applies self-service by enabling the control system to automatically adjust and optimize its own operation. The system self-regulates filament voltage based on measured anode current and tube conditions, adapting to degradation and environmental factors without requiring external intervention or complex manual calibration, thus maintaining ease of use while improving adaptability.
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 adaptive control system significantly improves the transient response of X-ray tube control systems, enabling more precise and responsive operation, particularly for short-term exposures, by dynamically adjusting voltages based on real-time measurements and desired current profiles.
Implementation Method 1
the X-ray tube of the equipment must emit X-rays. In order for the X-ray tube to emit X-rays, a high voltage is applied between its cathode and its anode
Implementation Method 2
a low voltage is applied to its filament
Data Source
Figure 1
Figure 2
AI summary
The radiological equipment (1) comprises an X-ray tube (10) and a control system (30) adapted to control the X-ray tube (10); the control system (30) has: a first output (32) adapted to provide a first signal (HV) to the X-ray tube (10) corresponding to an anode voltage, a second output (34) adapted to provide a second signal (LV) to the X-ray tube (10) corresponding to a filament voltage, a first input (36) adapted to receive (20) a third signal (AI) corresponding to detected anode current values (MI(n)), a second input (38) adapted to receive a user command from an interface system (40) relating to a desired value (DI) of anode current for an exposure to be performed through the equipment; the control system (30) is adapted to generate the first signal (HV) and the second signal (LV) as a function of detected values (MI(n)) and the desired value (DI); the control system (30) implements an adaptive control at least as far as said first signal (HV) is concerned.