Helical Electromagnetic Linear Actuator for Prosthetics
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Solution Overview
Problem
Existing linear actuators are not compact, lightweight, and efficient enough for portable applications such as prosthetics and robotics, lacking high control over mechanical energy transformation and generating significant noise due to mechanical interconnections.
Innovation Solution
A compact actuator design featuring a stator with electromagnetic sectors and cylindrical elements with radial permanent magnets arranged in helices, allowing for efficient energy transformation through phased electromagnetic fields without mechanical gears, reducing friction and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If traditional mechanical linear actuators are used, then linear motion can be achieved, but the device becomes heavy, bulky, and generates significant noise due to mechanical interconnections
Solution Approach 1:
The patent replaces the traditional mechanical transmission system (gears, lead screws, belts) with a direct-drive electromagnetic motor system. The motor's rotor is directly coupled to the moving platform, eliminating mechanical interconnections that generate noise and add weight. This substitution of mechanical components with electromagnetic fields achieves linear motion without the harmful effects of mechanical friction and impact noise.
Solution Approach 2:
The patent extracts and removes the mechanical transmission components (gears, shafts, belts, and their supporting structures) from the actuator system. By taking out these unnecessary mechanical elements, the design achieves direct electromagnetic drive, significantly reducing the overall weight and eliminating the noise sources associated with mechanical meshing and friction.
2Use of energy by moving object
If mechanical transmission components are used, then motion control can be achieved, but friction increases leading to energy loss and reduced efficiency
Solution Approach 1:
The patent substitutes mechanical transmission components with an electromagnetic field-based direct drive system. The electromagnetic motor generates force directly through electromagnetic interaction between the stator and rotor, eliminating the need for mechanical gears, belts, or lead screws that create friction and energy loss. This results in significantly improved energy efficiency.
3Volume of moving object
If compact design is pursued, then portability is improved, but existing actuators lack sufficient power and control precision
Solution Approach 1:
The patent merges the motor function and the linear actuation function into a single integrated electromagnetic system. The stator generates electromagnetic fields that directly interact with the rotor to produce both rotational motion and linear thrust simultaneously, eliminating the need for separate motor and transmission components. This consolidation achieves compact volume while maintaining high power output.
Solution Approach 2:
The patent transitions from traditional rotational motor output to direct linear motion output by utilizing the electromagnetic interaction in a different dimensional configuration. The stator and rotor are arranged to generate electromagnetic forces that directly propel the moving platform linearly, rather than requiring conversion from rotational to linear motion through mechanical components. This dimensional change enables compact design with sufficient thrust.
4Reliability
If mechanical interconnections are used, then structural stability can be achieved, but durability decreases due to wear and friction over time
Solution Approach 1:
The patent replaces mechanical interconnections with an electromagnetic field-based direct drive system. The electromagnetic motor generates force through field interaction without mechanical contact between moving parts, eliminating wear and friction that limit the service life of mechanical actuators. This substitution significantly improves reliability and duration of operation.
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 actuator achieves efficient, quiet, and highly controllable mechanical energy conversion, suitable for prosthetics and robotics, with reduced noise and increased durability due to the absence of mechanical interconnections, enabling long-term operation and energy conservation.
Implementation Method 1
a stator having electromagnetic sectors for generating phased electromagnetic fields around the stator
Implementation Method 2
Phased magnetization of the stator causes the cylindrical element to rotate around the axis along a helical path, thereby exerting a longitudinal force along the axis
Implementation Method 3
The cylindrical element comprises permanent magnetic elements magnetized radially and arranged as one or more discontinuous helices
Data Source
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AI summary
An actuator that transforming electrical energy into mechanical energy (or vice-versa) that is particularly suited to portable applications requiring a high degree of efficient control, e.g. applications in which human-like movement needs to be simulated or interacted with. The actuator has a stator comprising electromagnetic sectors for generating phased electromagnetic fields around the stator and at least one cylindrical element (and preferably two such elements). The stator and the cylindrical element(s) are arranged concentrically around a central axis. The cylindrical element has permanent magnetic elements magnetized radially and arranged as one or more discontinuous helices. Phased magnetization of the stator causes the cylindrical element to rotate around the axis along a helical path, thereby exerting a longitudinal force along the axis. Preferably one cylindrical element rotates along a helical path relative to another cylindrical element that has permanent magnetic elements magnetized radially and arranged in one or more helices. Applications of the actuator include prosthetic limbs and orthoses, and for service and remotely operated robots.