System and method for a prosthetic hand having sensored brushless motors
Inventors
Cornman, Jesse • Akhtar, Aadeel
Assignees
Publication Number
US-11399967-B2
Publication Date
2022-08-02
Expiration Date
2040-03-30
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Abstract
A system and method for a prosthetic assembly that includes a first prosthetic component, comprising a prosthetic hand base; a set of second prosthetic components, comprising a set of prosthetic fingers, and a set of actuating systems, wherein one actuating system connects a pair of distinct prosthetic components, enabling actuation of one prosthetic component with respect to the other. Each actuating system, from the set of actuating systems, includes a linkage and a sensored brushless motor; wherein the sensored brushless motor comprises a brushless motor, a field oriented control system, a rotary encoder, and a gearbox.
Core Innovation
The invention provides a system and method for a prosthetic assembly, particularly for a prosthetic hand, that utilizes sensored brushless motors for actuating prosthetic fingers relative to a hand base. Each actuating system between the hand base and a prosthetic finger comprises a linkage and a sensored brushless motor, which itself includes a brushless motor, a field oriented control (FOC) system, a rotary encoder, and a gearbox. The sensored brushless motors are miniaturized to fit within the prosthetic hand and provide sufficient power, precision, and durability for actuating multiple finger components.
A main challenge in prosthetic technology has been balancing motor size with sufficient power, reaction speed, and durability; traditionally, small motors that fit inside prosthetic hands are weak and slow, while powerful motors are too large. This invention addresses this limitation by enabling the integration of multiple miniaturized sensored brushless motors in a single prosthetic hand, achieving high torque, high precision, and reliable actuation, while remaining compact enough to fit into the limited space of a prosthetic limb.
The invention further includes features such as identical calibration of the sensored brushless motors for universal interchangeability, compliant 4-bar linkages for finger actuation, non-backdrivable or backdrivable gearboxes for tailored finger and thumb functionality, and centralized control circuitry implemented on a printed circuit board within the hand base. This design supports independent and simultaneous finger actuation with increased power efficiency, high-level coordination, and improved durability compared to previous prosthetic motor systems.
Claims Coverage
The patent contains two independent claims, each outlining key inventive features of the prosthetic hand system and method for implementing sensored brushless motors.
Prosthetic hand system with sensored brushless motor-driven actuation
A prosthetic assembly system including: - A prosthetic hand with a hand base and a set of prosthetic fingers. - A set of actuating systems, where each actuating system connects a prosthetic finger to the hand base and provides locomotion for finger actuation. - Each actuating system comprises a linkage mechanically coupling the prosthetic finger to the hand base, and a sensored brushless motor. - The sensored brushless motor includes: - A brushless motor - A field oriented control (FOC) control system - A rotary encoder - A gearbox
Method for implementing sensored brushless motors with a prosthetic assembly
A method comprising: 1. Integrating an encoder with a brushless motor, including: - Fixing a diametrically magnetized magnet to the motor rotor - Mounting an encoder above the magnet so they are axially aligned 2. Calibrating the brushless motor with the encoder 3. Embedding the motor between a first prosthetic component (hand base) and a second prosthetic component (prosthetic finger) 4. Controlling the motor through a field oriented control (FOC) mode
In summary, the claims cover a prosthetic hand system utilizing miniaturized, sensored brushless motors with dedicated control, linkage, gearbox, and calibration features for precise, customizable finger actuation, and a corresponding method for assembling, calibrating, and controlling these components.
Stated Advantages
The FOC sensored brushless motors provide greater strength and efficiency in actuation, resulting in better grip strength and reduced battery consumption.
The system enables a higher level of precision, allowing for coordinated actuation among multiple hand components and subtle mechanical adjustments for various tasks.
FOC sensored brushless motors produce much less sound than brushed motors, resulting in quieter operation.
The motors offer high torque at slow speeds, supporting a prosthetic hand's ability to grip objects without slipping.
The system enables faster motion, allowing the prosthetic hand to open and close significantly quicker than competitor systems.
Sensored brushless motors require less power compared to similar capacity brushed motors, extending operational time and enabling simultaneous actuation of multiple motors.
High power and precision make possible complex manipulations and coordinated actions, such as knot-tying and catching objects.
Brushless motors provide greater longevity, leading to a prosthesis with an extended lifespan and less frequent repairs or replacements.
Use of non-backdrivable gearboxes allows a prosthetic hand to maintain grip without ongoing motor energy, enhancing energy efficiency.
Miniaturized motor components create a lighter prosthetic assembly, increasing comfort and reducing user fatigue.
Identical calibration of brushless motors allows prosthetic fingers to be hot-swappable, simplifying maintenance and replacement.
Documented Applications
Actuation of prosthetic hands, enabling lifelike movement and independent control of prosthetic fingers.
General use with various prostheses, including knee, thigh, elbow, toe, ankle, and pharyngeal finger joints.
Implementation in exoskeletons or other suitable systems requiring precise, miniaturized motor actuation.
Providing limb functionality for persons or animals needing a replacement limb, or for demonstration or study purposes.
Enabling additional limb functionality a-la carte, such as providing a third hand or a demonstration limb.
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