LRA Impedance Tracking via Adaptive BEMF Extraction
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Solution Overview
Problem
Existing Linear Resonant Actuator (LRA) systems face inefficiencies in real-time impedance tracking and BEMF extraction, as current methods require halting the driving signal to sense BEMF, leading to reduced efficiency and limited acceleration due to high-impedance architectures.
Innovation Solution
A method and apparatus for real-time impedance tracking and BEMF extraction using an adaptive algorithm that determines a current multiplying factor and introduces an error function to control the gain of the load current, allowing simultaneous driving and BEMF extraction without halting the signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If BEMF sampling is performed using high-impedance mode architecture, then BEMF can be sensed directly, but the driving signal must be halted which reduces efficiency and acceleration
Solution Approach 1:
The patent implements continuous driving of the LRA by extracting BEMF from the load current during active operation rather than halting the drive signal. The BEMF is obtained by measuring the load current and using an adaptive algorithm to separate the BEMF component from the driving signal, allowing both driving and sensing to occur simultaneously without interruption to the useful action of actuator operation
Solution Approach 2:
The patent uses load current measurement as an intermediary to indirectly sense the BEMF voltage. Instead of directly measuring BEMF voltage which requires halting the drive signal, the system measures the load current and uses signal processing to extract the BEMF component, allowing continuous operation while obtaining the necessary measurement data
2Measurement precision
If the driving signal is halted for BEMF sampling, then accurate BEMF measurement can be obtained, but acceleration and efficiency are reduced
Solution Approach 1:
The system maintains continuous driving signal to the LRA while simultaneously extracting BEMF information from the load current. The adaptive algorithm processes the load current in real-time to separate the BEMF component, ensuring that both the driving function and measurement function occur continuously without interruption to actuator acceleration or positioning speed
3Reliability
If real-time impedance tracking is implemented, then actuator health monitoring is improved, but system complexity increases
Solution Approach 1:
The system performs impedance tracking and health monitoring using the existing load current measurement infrastructure without requiring separate dedicated sensing hardware. The adaptive algorithm processes the already-acquired load current data to extract impedance information and detect actuator health status, allowing the system to self-monitor using its operational data
Solution Approach 2:
The load current measurement serves multiple functions simultaneously: it drives the actuator operation, enables BEMF extraction for position sensing, and provides impedance tracking for health monitoring. This multi-functional use of the same measurement channel reduces the need for additional dedicated components and simplifies the overall system architecture
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 continuous driving of LRA systems, improving efficiency by allowing real-time impedance tracking and BEMF extraction, enhancing actuator health monitoring, aging estimation, and failure prediction while maintaining consistent energy delivery and reducing the risk of over-excursion.
Implementation Method 1
extracting the Back Electro-Motive Force (BEMF) voltage from a driver's load current
Data Source
AI summary
A method, apparatus and a system for a Linear Resonant Actuator (LRA) real time impedance tracking. The method includes extracting the Back Electro-Motive Force (BEMF) voltage from a driver's load current by determining a current multiplying factor utilizing a Least Mean Square (LMS) algorithm and introducing an error function to control the gain of the load current and isolate the BEMF.