Multi-Motor Actuator for Joint Extension and Flexion
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Solution Overview
Problem
Conventional Continuously Variable Transmissions (CVTs) in actuator systems are inefficient and mechanically complex, limiting their ability to provide variable force and speed ranges, and single-motor systems require additional transmission components or complexity to achieve similar functionality.
Innovation Solution
A multi-motor assembly with two brushless electric motors and adjustable gear ratios, combined with a rotary-to-linear mechanism and a controller that operates in various modes to supply larger forces at slower speeds and smaller forces at higher speeds, eliminating the need for conventional CVTs and additional transmission components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional CVTs are used to achieve variable force and speed ranges, then the actuator can supply larger forces at slower speeds and smaller forces at higher speeds, but the system becomes mechanically complex and inefficient
Solution Approach 1:
The system divides the single actuator into two independent motor subsystems (first and second motor subsystems), each capable of operating independently. This segmentation eliminates the need for complex CVT mechanisms while achieving variable force and speed output by selectively activating one subsystem or the other based on operational requirements.
Solution Approach 2:
The controller dynamically switches between different motor subsystems and operational modes (first operational mode, second operational mode, and third operational mode) based on real-time force and speed requirements. This dynamic reconfiguration allows the system to adapt its characteristics without mechanical transmissions.
2Device complexity
If a single motor is used to provide motion for each output direction, then the system is simpler, but the speed/torque range is limited and additional transmission components are required
Solution Approach 1:
Instead of using a single motor with complex transmission, the system segments the propulsion function across two motor subsystems. Each subsystem is optimized for different operational characteristics, and the controller selects which subsystem to activate based on the required speed and torque, achieving wide range adaptability without transmissions.
Solution Approach 2:
Both motor subsystems are connected to the same drive shaft and can independently provide rotational output. This multi-functionality allows the system to achieve various speed and torque combinations by selecting between subsystems, eliminating the need for dedicated transmission components for each output requirement.
3Adaptability or versatility
If conventional CVTs are implemented to change gear ratios, then variable speed and force output is achieved, but efficiency is reduced due to mechanical losses
Solution Approach 1:
The system replaces the mechanical CVT transmission system with an electronic control system that selectively activates different motor subsystems. This substitution eliminates mechanical friction, belt slip, and gear meshing losses inherent in conventional CVTs, significantly improving overall system efficiency while maintaining variable force and speed output capability.
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
The multi-motor assembly enables efficient and flexible force and speed variations without the inefficiencies and complexity of traditional CVTs, allowing for compact and effective actuation in applications like robotics and orthotics.
Implementation Method 1
two brushless electric motors
Data Source
AI summary
An actuator system for extending and flexing a joint, including a multi-motor assembly for providing a rotational output, a rotary-to-linear mechanism for converting the rotational output from the multi-motor assembly into an extension and flexion of the joint, and a controller for operating the actuator system in several operational modes. The multi-motor assembly preferably combines power from two different sources, such that the multi-motor assembly can supply larger forces at slower speeds (“Low Gear”) and smaller forces at higher speeds (“High Gear”). The actuator has been specifically designed for extending and flexing a joint (such as an ankle, a knee, an elbow, or a shoulder) of a human. The actuator system may, however, be used to move any suitable object through any suitable movement (linear, rotational, or otherwise).