Asymmetric Electrode Design for Linear Switched Capacitive Actuators
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Solution Overview
Problem
Conventional linear switched capacitance actuators (SCAs) face limitations in achieving parity with electromagnetic machines in terms of power-to-weight ratio and motion-induced shear stress, particularly in robotic and aviation applications, due to lower shear stress and higher weight, which is exacerbated by the complexity of vacuum configurations required to enhance dielectric breakdown strength.
Innovation Solution
The design incorporates a switched capacitive device with a stationary portion and a translatable portion, where the stationary electrodes have a greater active electrode volume than the translatable electrodes, inducing linear motion through an electric field, and utilizes printed circuit boards to generate translational forces, eliminating the need for iron cores and transmission gears, thereby reducing weight and copper usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the active area of the air gap is increased to achieve parity with electromagnetic devices in power-to-weight ratio, then the shear stress is improved, but the device size and weight increase
Solution Approach 1:
The patent applies local quality by creating asymmetric electrode configurations where stationary electrodes have different dimensions than translatable electrodes. Specifically, the stationary electrodes extend further in the longitudinal direction and have greater active electrode volume, concentrating the electric field generation where needed while minimizing the weight of moving components. This resolves the contradiction by optimizing force generation locally rather than uniformly across the entire device.
Solution Approach 2:
The patent inverts the conventional approach by making the stationary portion heavier and more substantial than the translatable portion. Instead of minimizing stationary component weight, the design accepts increased stationary electrode volume to generate sufficient electric field strength, thereby reducing the weight burden on moving parts. This inversion resolves the power-to-weight ratio issue by decoupling force generation mass from moving mass.
2Strength
If vacuum configuration is used to increase dielectric breakdown strength, then the electric field strength is improved, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing the dielectric material properties and electrode geometry rather than relying on vacuum conditions. By adjusting the dielectric strength parameter of the material filling the air gap and modifying electrode dimensions, the design achieves high electric field strength without the complexity of vacuum sealing, pumping, and maintenance systems.
Solution Approach 2:
The patent extracts the vacuum requirement from the system by using alternative methods to achieve high dielectric breakdown strength. Instead of removing air to create vacuum, the design uses properly selected dielectric materials and electrode configurations to achieve the necessary electric field strength, thereby eliminating the complex vacuum subsystem while maintaining or improving performance.
3Power
If stationary electrodes have greater active electrode volume than translatable electrodes, then the electric field induction is improved, but the weight distribution becomes asymmetric
Solution Approach 1:
The patent inverts the conventional weight distribution paradigm by deliberately making stationary electrodes heavier than translatable electrodes. This asymmetric design prioritizes electric field generation capability in the stationary portion, accepting uneven weight distribution as a trade-off for superior power induction. The translatable portion remains lightweight to minimize moving mass, while the stationary portion provides substantial field-generating capacity.
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
This configuration enhances energy efficiency, reduces weight and size, and increases the power-to-weight ratio, providing a high-efficiency linear actuator suitable for applications like robotics and aviation by leveraging electric field-based energy conversion and minimizing copper and iron losses.
Implementation Method 1
The plurality of first electrodes are configured to induce substantially linear motion of the plurality of second electrodes in the longitudinal dimension through the use of an electric field induced by at least a portion of the plurality of first electrodes
Data Source
AI summary
A switched capacitive device includes a stationary portion including a plurality of first electrodes extending at least partially in a longitudinal dimension. Each first electrode has a first substantially active electrode volume. The device also includes a translatable portion including a plurality of second electrodes proximate the plurality of first electrodes. Each second electrode has a second substantially active electrode volume. The first active electrode volume is greater than the second active electrode volume. The second electrodes are translatable with respect to the first electrodes. The second electrodes extend at least partially in the longitudinal dimension. The first electrodes are configured to induce substantially linear motion of the second electrodes in the longitudinal dimension through the use of an electric field induced by at least a portion of the first electrodes.