Multi-Phase Linear Haptic Actuator with Back-EMF Position Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Haptic devices face challenges in providing precise tactile feedback without generating noise, as they often require mechanical limit stops that can cause the field member to crash, leading to unwanted vibrations and noise.
Innovation Solution
A linear haptic actuator with a multi-phase coil arrangement and a closed-loop controller that senses the position of the field member using back EMF, allowing for the actuator to be driven without contacting mechanical limit stops, thereby reducing noise and improving feedback precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If mechanical limit stops are used to constrain the field member movement, then the actuator structure is simplified, but noise and vibrations increase due to crashing
Solution Approach 1:
The patent replaces mechanical limit stops with a magnetic field-based sensing and control system. The controller uses feedback from the magnetic field to detect field member position and electronically controls the coil currents to prevent mechanical contact, substituting mechanical constraint with electromagnetic control to eliminate crashing noise and vibrations
Solution Approach 2:
The patent implements a closed-loop feedback system where the controller continuously monitors the magnetic field generated by the coils to determine field member position, and adjusts the coil currents accordingly to maintain precise control without mechanical contact, preventing the field member from reaching mechanical limit stops
2Measurement precision
If multi-phase coil arrangement with sensing is implemented, then position control precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the coils multi-functional by using them for both actuation (driving the field member) and sensing (detecting position through magnetic field measurement). This eliminates the need for separate sensing components, reducing overall device complexity while maintaining high position control precision through the multi-phase arrangement
Solution Approach 2:
The patent merges the actuation and sensing functions into a single integrated system where the same coils perform both roles. The controller distinguishes between drive phases and sense phases, combining what would traditionally be separate components into one unified structure, thereby improving precision without proportionally increasing complexity
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 solution enables the haptic actuator to provide precise and noise-reduced tactile feedback by accurately controlling the movement of the field member, enhancing user experience and device performance.
Implementation Method 1
a plurality of coils carried by the housing, and a field member linearly movable within the housing and that includes at least one permanent magnet cooperating with the plurality of coils
Implementation Method 2
at least one permanent magnet cooperating with the plurality of coils
Implementation Method 3
The controller may be configured to sense the position of the field member based upon a back electromotive force (EMF) from each of the plurality of coils
Data Source
AI summary
An electronic device may include a linear haptic actuator that may include a housing, coils carried by the housing, and a field member linearly movable within the housing and that may include at least one permanent magnet cooperating with the coils. The electronic device may also include a controller configured to drive the coils in a multi-phase arrangement so that at least one coil is driven while at least one other coil is used to sense a position of the field member.