Sensor-Less DC Motor Angle Feedback for Imaging Capsules
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Solution Overview
Problem
Existing imaging capsules for gastrointestinal tract examination face challenges in accurately determining the direction of the collimator and detector to reconstruct precise images of the colon or small bowel, while also requiring a compact and efficient motor system to minimize capsule size.
Innovation Solution
The use of a brushed DC motor with a segmented commutator that provides a pulsed signal indicating rotation angle, allowing for accurate scanning of the inner wall of the colon, combined with a shutter mechanism for controlled radiation emission and a backup power source for safety, and a high pass and low pass filter for processing the pulsed output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a brushed DC motor with segmented commutator is used, then the motor size is minimized, but the measurement precision of rotation angle is compromised
Solution Approach 1:
The segmented commutator serves dual functions: it provides electrical power to the motor windings and simultaneously generates rotation angle measurement signals. The brushes reading the segmented commutator segments during normal motor operation produce pulsed signals that indicate motor rotation, eliminating the need for separate sensors or encoders.
Solution Approach 2:
The segmented commutator structure performs multiple functions within a single component: electrical power transmission to the armature and angular position encoding. This multi-functionality resolves the contradiction by using existing motor components for both drive and measurement purposes, avoiding additional space-consuming parts.
2Measurement precision
If the collimator and detector rotation direction is accurately determined, then image reconstruction precision is improved, but the device complexity increases
Solution Approach 1:
The pulsed signals from the brushes reading the segmented commutator provide real-time feedback on motor rotation position. This feedback enables the control system to accurately determine the angular position of the collimator and detector, ensuring precise image reconstruction without requiring complex external positioning systems.
Solution Approach 2:
The motor drive system and position measurement system are merged into a single integrated unit. The segmented commutator and brushes that are inherently part of the DC motor structure also serve as the position encoding mechanism, combining drive and measurement functions in one system rather than using separate components.
3Volume of moving object
If the capsule size is minimized, then patient comfort and safety are improved, but the motor power and scanning efficiency are reduced
Solution Approach 1:
The motor operates in periodic cycles, rotating the collimator and detector through the colon circumference multiple times. The segmented commutator provides timing signals that synchronize with these periodic rotations, allowing efficient data acquisition during each rotation cycle while maintaining a compact capsule design.
Solution Approach 2:
The motor provides continuous rotation capability throughout the scanning process, with the segmented commutator continuously generating position signals. This continuous operation maintains scanning efficiency despite the compact size, as the motor can sustain rotation without interruption or external intervention.
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 configuration enables precise reconstruction of images by determining photon counts per angular sector, ensuring accurate and efficient scanning with minimal energy consumption and enhanced safety features for radiation control.
Implementation Method 1
the motor provides a pulsed output signal based on mechanical switching of the segmented commutator on the brush contacts
Implementation Method 2
The imaging capsule typically includes a radiation source, for example including a radioisotope that emits X-rays or Gamma rays
Implementation Method 3
a detector to detect particles from X-ray fluorescence and/or Compton back-scattering
Implementation Method 4
a detector to detect particles from X-ray fluorescence and/or Compton back-scattering
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
An imaging capsule, including a radiation source, a collimator that provides a collimated beam from the radiation source, a detector configured to detect particles resulting from X-ray fluorescence and/or Compton backscattering in response to the collimated beam, a motor to rotate the collimator and detector around an axle to scan a partial or full inner circumference of a user's colon with radiation, wherein the motor comprises a segmented commutator that is fed with a power signal via brush contacts; and wherein the motor provides a pulsed output signal based on mechanical switching of the segmented commutator on the brush contacts, providing an indication of the rotation angle of the motor as a function of time.