Double-Wound Haptic Actuator Coil for Velocity Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional haptic engines face challenges in accurately sensing the velocity of a haptic actuator's moving mass due to temperature variations and the need for precise current sensing, which are sensitive to coil resistance changes and common-mode rejection.
Innovation Solution
A haptic engine with a double-wound driving coil, where the two windings are connected in series or parallel, allowing for the determination of back EMF voltage without real-time resistance measurement or current sensing, thereby reducing sensitivity to temperature variations and common-mode rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single-wound coil with bEMF sensing is used, then velocity sensing capability is provided, but measurement precision deteriorates due to temperature variations and coil resistance changes
Solution Approach 1:
The single coil is divided into two separate windings (first winding and second winding) that are thermally coupled. Each winding generates its own back EMF signal, allowing the system to segment the measurement process and eliminate dependence on coil resistance through mathematical combination of the two signals.
Solution Approach 2:
The patent introduces an intermediary computational process that combines the back EMF signals from both windings using their known resistance ratio. This intermediary calculation eliminates the need for real-time resistance measurement and compensates for temperature variations, serving as a mediator between the physical windings and the final velocity measurement.
2Measurement precision
If real-time current sensing is implemented for bEMF measurement, then velocity determination capability is improved, but device complexity increases due to additional sensing circuitry and impedance measurement requirements
Solution Approach 1:
The patent extracts and eliminates the need for real-time current sensing circuitry by using the dual-winding configuration. The velocity can be determined from back EMF measurements alone, without requiring separate current sensors or complex impedance measurement systems, thereby simplifying the overall device architecture.
Solution Approach 2:
The two windings serve multiple functions: they both generate driving force when current flows through them, and simultaneously serve as sensors by generating back EMF signals. This multi-functionality eliminates the need for separate sensing components, reducing device complexity while maintaining measurement precision.
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 enables robust and accurate velocity determination of the haptic actuator's mass, reducing the need for complex sensing circuitry and eliminating the requirement for real-time impedance measurements, leading to more efficient and effective haptic actuator operation.
Implementation Method 1
a back electromotive force voltage, or simply bEMF, induced in the driving coil, or simply coil, is related to the velocity of the moving mass
Implementation Method 2
A haptic actuator in which a mass is driven using electromagnetic forces to move relative the haptic actuator's frame
Data Source
AI summary
A haptic engine includes a haptic actuator having a double-wound driving coil in which the two windings are connected with each other either in series or in parallel. By using the double-wound driving coil in which the two windings are connected with each other in series, an instant back EMF voltage induced in either of the two windings can be determined without having to measure in real time a resistance of the corresponding winding, and without having to sense a driving current through the double-wound driving coil. By using the double-wound driving coil in which the two windings are connected with each other in parallel, an instant back EMF voltage induced in either of the two windings can be determined without having to measure in real time a resistance of the corresponding winding.