A medical device manufacturer developing a next-generation patient positioning system for diagnostic imaging needed a drive motor that existing catalog offerings could not satisfy across all required performance dimensions simultaneously.
A medical device manufacturer developing a next-generation patient positioning system for diagnostic imaging needed a drive motor that existing catalog offerings could not satisfy across all required performance dimensions simultaneously.
The application required a motor that could deliver precise torque control with sub-degree positioning accuracy across a 270-degree range of motion; operate within strict acoustic noise limits (38 dBA or below at 0.5m) to preserve the clinical environment; survive a validated 10-year service life at a 50-cycle-per-day duty cycle; and do all of this within a package weight and volume 40% smaller than the existing brushed DC motor it would replace.
The brushed DC motor being replaced had served the previous product generation adequately. But the new platform's patient weight capacity had been increased by 35%, and the positioning system's new range of motion required a motor with a fundamentally different torque density profile.
Catalog BLDC motors in the required torque range exceeded the acoustic noise limit or the package volume constraint. The device's FDA submission was tied to a specific system weight target that made the 40% weight reduction a hard requirement, not a design preference.
A secondary constraint: the motor needed to support the device's safety architecture. In the event of a controller failure, the motor had to hold position passively, requiring specific rotor design parameters.
One partner. One specification. Full accountability.
TelcoMotion's engagement began with a formal requirements analysis against the device's design input documentation, using the same requirements traceability framework used in the FDA design control process.
Motor Topology Selection: A fractional-slot concentrated winding (FSCW) BLDC topology was selected. FSCW motors deliver higher torque per unit mass than distributed-winding designs, directly addressing the torque density requirement. The fractional-slot configuration also reduces cogging torque, a primary contributor to acoustic noise at low speeds.
Acoustic Optimization: Slot and pole count were optimized through FEA simulation to minimize cogging torque to under 1% of rated torque. The rotor was balanced to G2.5 grade. Bearing preload was specified and validated to eliminate the bearing-raceway noise contribution.
Weight Reduction: The FSCW topology with a high-energy density NdFeB rotor magnet achieved the required torque in a package 43% lighter than the brushed DC motor it replaced, meeting the system weight target with margin.
Passive Hold Capability: Rotor detent torque was specified at 15% of rated continuous torque, sufficient to hold patient positioning under gravity loading in the event of a controller de-energization event.
Documentation Package: TelcoMotion supplied a full design history file including dimensional and performance drawings, material declarations, accelerated life test data (10,000 cycle equivalent at elevated temperature), and first article inspection reports structured to support the OEM's FDA 510(k) submission.
Results that compound
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Closed-loop precision servo systems for dynamic positioning and synchronization.
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