Electromechanical Actuator Domain Polarization Control
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Solution Overview
Problem
Existing electromechanical actuators face challenges in achieving fine and defined adjustment movements with deformations caused by electric fields that do not persist without the applied voltage, leading to discontinuous deformation changes and limited travel range.
Innovation Solution
A method for controlling an electromechanical element with a changing section using a polycrystalline and ferroelectric or piezoelectric material, where an electric field is generated by voltage pulses to permanently change domain polarization, resulting in defined expansion or contraction that remains without electrical voltage, utilizing electrodes and carefully dimensioned voltage pulses to achieve controlled deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If voltage pulses are applied to generate domain flipping in ferroelectric-piezoelectric material, then deformation jumps and extended travel range are achieved, but discontinuous deformation changes occur which are disadvantageous for fine adjustment movements
Solution Approach 1:
The actuator is divided into two distinct sections: a first section utilizing piezoelectric effect for continuous deformation, and a second section utilizing ferroelectric-piezoelectric material for discontinuous deformation jumps. This segmentation allows each section to perform its specialized function while working together to achieve both fine adjustment and extended travel range.
Solution Approach 2:
The actuator employs a composite structure combining piezoelectric material and ferroelectric-piezoelectric material in different sections. This composite approach leverages the continuous deformation capability of piezoelectric material and the large deformation jump capability of ferroelectric-piezoelectric material to resolve the contradiction between precision and travel range.
2Reliability
If conventional piezoelectric actuators are used, then continuous and reversible deformation is achieved, but the deformation disappears when electrical voltage is removed which limits positional stability
Solution Approach 1:
The patent changes the material parameter from conventional piezoelectric material to ferroelectric-piezoelectric material in the second section. This parameter change enables the material to exhibit hysteresis behavior and retain deformation after voltage removal, thereby achieving persistent deformation and improved positional stability.
Solution Approach 2:
The actuator uses periodic voltage pulses to induce domain flipping in the ferroelectric-piezoelectric material. Each pulse creates a permanent deformation step that accumulates over time, allowing the actuator to build up and maintain positional changes through repeated pulsing even after individual pulses end.
3Adaptability or versatility
If the complete electromechanical element is used as the changing section, then the method applies to the entire actuator, but the complexity of controlling the complete element increases
Solution Approach 1:
The actuator is segmented into a first section and a second section with distinct material properties and control characteristics. This segmentation simplifies control by allowing independent optimization of each section - the first section for fine continuous adjustments and the second section for larger discrete steps - rather than controlling the complete element as a single complex unit.
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
Enables precise and persistent deformation changes in electromechanical elements, allowing for fine adjustment movements with increased travel range and stability, as the deformation induced by voltage pulses remains even after the voltage is removed, enhancing the actuator's positional stability and accuracy.
Implementation Method 1
the utilization of the piezoelectric effect in the other layers of the actuator leads to a linear and continuous deformation change
Implementation Method 2
An actuator with several layers of a piezoelectric-ferroelectric material is known from US Pat domain state or vice versa, i. H. through a domain flip. As a result of said domain flipping, discontinuous changes in deformation, i. H. Deformation jumps are achieved in these layers
Data Source
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AI summary
The invention relates to a method for activating at least one portion, to be specific a change portion, of an electromechanical element (3), comprising the following steps: providing an electromechanical element, wherein at least the change portion has at least two electrodes, which are spaced apart from one another, and arranged between the electrodes a polycrystalline and ferroelectric or ferroelectric-piezoelectric material with a multiplicity of domains, wherein, in an initial state, at least some of the domains have directions of polarization that are different from one another; generating an electrical field between the electrodes of the change portion by applying an electrical voltage in the form of at least one voltage pulse with a defined amplitude and a defined duration; transforming some of the domains with directions of polarization that are different from one another into a state of the same direction of polarization as a result of the at least one voltage pulse, and thereby producing an increase in the extent of the electromechanical element along a direction of extent V that is defined and persists without the presence of an electrical voltage, or transforming some of the domains with the same direction of polarization into a state with directions of polarization that differ from one another as a result of the at least one voltage pulse, and thereby producing a decrease in the extent of the electromechanical element along the direction of extent V that is defined and persists without the presence of an electrical voltage. The invention also relates to the use of an electromechanical element activated by this method as an adjusting element and to the arrangement of an electromechanical element activated by this method between two elements (1, 2) that are to be moved with respect to one another.