Haptic Actuator Position Control via Back-EMF Decoupling
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Solution Overview
Problem
Current haptic technologies face challenges in accurately determining the position and efficiently driving a field member in multiple dimensions using back electromotive force (EMF) values and motor constant values, often resulting in reduced accuracy and efficiency due to coupling effects from z-axis displacement.
Innovation Solution
A haptic actuator design featuring a housing with multiple coil pairs, a field member with permanent magnets, and flexure bearings, where a controller senses and drives each coil pair independently to determine and control the field member's position in x, z, and rotational dimensions, optimizing motor constant usage and reducing z-axis offset impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If back EMF values and motor constant values are used to determine field member position, then position determination can be achieved without additional sensors, but accuracy is reduced due to coupling effects from z-axis displacement
Solution Approach 1:
The patent segments the position determination process by separately analyzing back EMF values from different coil pairs. By processing x-axis and z-axis position information independently through selective coil pairing, the system resolves coupling effects that would otherwise degrade measurement precision.
Solution Approach 2:
The patent applies local quality by selecting specific coil pairs based on the desired measurement axis. Different coil pairs are activated depending on whether x-axis or z-axis position is being determined, optimizing the measurement quality for each specific directional requirement while maintaining overall system simplicity.
2Adaptability or versatility
If multiple coil pairs are driven simultaneously to control field member in multiple dimensions, then multi-dimensional control is achieved, but efficiency is reduced due to coupling effects
Solution Approach 1:
The patent implements dynamic control by selectively activating different coil pairs based on the current operational requirements. The system dynamically adjusts which coils are driven to achieve the desired field member motion, optimizing energy efficiency while maintaining full multi-dimensional adaptability.
Solution Approach 2:
The patent employs periodic action through alternating activation of different coil pairs for sensing and driving operations. By periodically switching between different coil configurations, the system achieves efficient multi-dimensional control while minimizing energy consumption and reducing coupling effects.
3Device complexity
If z-axis displacement is not decoupled, then control simplicity is maintained, but position determination accuracy and driving efficiency are reduced
Solution Approach 1:
The patent extracts the z-axis displacement coupling effect from the overall control system by using specific coil pair combinations that are insensitive to z-axis position. This allows the system to maintain control simplicity while achieving high accuracy and efficiency in x-axis position determination and driving.
Solution Approach 2:
The patent introduces coil pair selection as an intermediary mechanism that decouples z-axis displacement effects. By mediating between the drive coils and the field member through selective activation, the system eliminates harmful coupling effects without adding complex control logic.
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 approach enhances the accuracy of position determination and driving efficiency by decoupling z-axis displacement, allowing for precise control and improved haptic feedback, including increased engine efficiency and reduced noise.
Implementation Method 1
A haptic actuator may include a housing, a plurality of coils carried within the housing, and a field member moveable within the housing between the plurality of coils and that includes at least one permanent magnet
Implementation Method 2
The controller may be configured to sense a respective back electromotive force (EMF) value of each of the plurality of coils and determine a position of the field member in a plurality of dimensions based upon the back EMF values and motor constant values
Data Source
AI summary
A haptic actuator may include a housing, coils carried within the housing, and a field member moveable within the housing between the coils and including at least one permanent magnet. A controller may be coupled to the coils and configured to sense a respective back electromotive force (EMF) value of each of the coils and determine a position of the field member in dimensions based upon the back EMF values and motor constant values.