Catheter Rotation Motor Sensing Windows for Clearer IVUS Imaging
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Solution Overview
Problem
Conventional intravascular ultrasound imaging systems suffer from electrical noise interference due to Pulse Width Modulation (PWM) drive signals, which manifest as speckles in the ultrasound images, hindering clear image interpretation.
Innovation Solution
Implementing a method that includes creating temporary sensing windows where the PWM drive signal is held constant to reduce electrical noise, adjusting rotation speeds before and after these windows, and using a digital drive motor with a varying drive signal to minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If PWM drive signal is used to control the drive motor, then the rotation speed of the ultrasound transducer can be precisely controlled, but electrical noise interference occurs in the ultrasound images
Solution Approach 1:
The patent divides the continuous PWM drive signal operation into segmented periods: active PWM drive periods for motor control and sensing windows where PWM switching is suspended for noise-free signal acquisition. This temporal segmentation resolves the contradiction by separating the motor control function from the ultrasound signal detection function in time.
Solution Approach 2:
The patent implements periodic sensing windows at predetermined intervals during the rotation cycle of the ultrasound transducer. During these periodic intervals, the PWM drive signal switching is temporarily halted to create noise-free measurement periods, while maintaining periodic motor control outside these windows. This periodic action allows precise speed control while eliminating electrical noise during critical detection phases.
2Measurement precision
If PWM switching is performed continuously, then motor control precision is maintained, but image quality deteriorates due to electrical noise
Solution Approach 1:
The patent segments the operational cycle into control phases (with PWM switching) and measurement phases (without PWM switching). The control phase maintains precise motor control through PWM, while the measurement phase prioritizes image quality by eliminating PWM-related electrical noise. This segmentation allows both precision requirements to be met in their respective phases.
Solution Approach 2:
The patent employs periodic sensing windows where PWM switching is temporarily suspended at regular intervals during the transducer rotation. This periodic interruption of PWM switching maintains adequate motor control precision over time while providing regular noise-free periods for high-quality ultrasound image acquisition, thus resolving the contradiction between control precision and image quality.
3Object-affected harmful factors
If sensing window is created by halting PWM switching, then electrical noise is reduced, but rotation speed stability is temporarily affected
Solution Approach 1:
The patent applies preliminary speed adjustment before entering the sensing window by modifying the PWM duty cycle. This preliminary action prepares the motor speed to compensate for the upcoming temporary halt in PWM switching, ensuring that rotation speed stability is maintained throughout the sensing window period and that the transducer completes its rotation cycle on time.
Solution Approach 2:
The patent implements feedback control by monitoring the actual rotation speed and adjusting the PWM duty cycle dynamically. During and after the sensing window, the feedback mechanism detects speed deviations and applies corrective PWM adjustments to restore and maintain the target rotation speed, thereby compensating for the temporary speed disruption caused by the sensing window and ensuring overall rotation stability.
Data Source
AI summary
Methods include capturing intravascular ultrasound images. A drive motor is used to actively drive an ultrasound transducer at a set rotation speed. A temporary sensing window is created in which the ultrasound transducer is driven with a fixed drive signal. A plurality of signals from are received the ultrasound transducer during the temporary sensing window.