Cradle Torque Control for X-ray CT Motor Synchronization
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Solution Overview
Problem
High-speed scanning in X-ray CT apparatuses often results in desynchronization of stepping motors, making it difficult to achieve efficient imaging, especially when accelerating from a stationary state, due to the inability to maintain constant torque across varying scanning speeds and ranges.
Innovation Solution
The implementation of a cradle unit and scanning gantry driving system that uses constant first and second torque values during distinct periods of acceleration, with the first torque value applied during initial acceleration from a stationary state and a smaller second torque value applied thereafter, to manage frictional forces and prevent desynchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cradle unit or scanning gantry is driven at higher speeds to increase scanning efficiency and range, then productivity is improved, but the stepping motor becomes desynchronized making reliable operation difficult
Solution Approach 1:
The patent applies dynamics by transitioning from constant torque control to acceleration-based torque control. The stepping motor control is divided into multiple acceleration stages (first acceleration, second acceleration, etc.) where the torque value is dynamically adjusted according to the current acceleration phase. This allows the motor to maintain synchronization while achieving higher scanning speeds and expanded scanning ranges.
Solution Approach 2:
The patent changes the torque parameter dynamically based on acceleration stages. Instead of using a fixed torque value, the control system adjusts the torque parameter through multiple stages: a first torque value during initial acceleration, a second torque value during subsequent acceleration, and so on. This parameter change approach prevents motor desynchronization while enabling higher productivity.
2Reliability
If constant torque is applied during acceleration to maintain motor synchronization, then reliability is improved, but the ability to achieve high scanning speeds is limited
Solution Approach 1:
The patent segments the acceleration process into multiple distinct stages, each with its own torque value. The acceleration is divided into first acceleration, second acceleration, and potentially further stages, with each stage having optimized torque parameters. This segmentation allows the system to maintain reliability in each stage while progressively achieving higher scanning speeds across the complete acceleration sequence.
3Reliability
If the torque value is increased to prevent motor desynchronization during acceleration, then reliability is improved, but the device complexity increases due to multiple torque control stages
Solution Approach 1:
The patent implements periodic action through time-based torque switching. The control system operates in distinct time periods corresponding to different acceleration stages, switching between predetermined torque values at predetermined time points. This periodic control approach maintains reliability through structured torque management while keeping the control logic relatively simple and systematic.
Data Source
AI summary
It is intended to implement imaging in an efficient way. In a first period in which a cradle unit is driven under acceleration from a stationary state, the cradle unit is driven with a constant first torque value. In a second period which comes after the lapse of the first period and in which the cradle unit is driven under acceleration, the cradle unit is driven with a constant second torque value which is smaller than the first torque value.