Transducer Excursion Control via Electrical Model Threshold
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Haptic transducers face challenges in measuring and controlling excursion to prevent damage from over-driving, as direct measurement methods like using a laser are impractical and disruptive, especially in production settings where the transducer casing cannot be opened.
Innovation Solution
A method and controller that utilize a stimulus input signal to determine a threshold electrical response, allowing for the generation of a limited transducer signal that prevents the transducer from exceeding this threshold, thereby protecting it from excessive excursion by using an electrical model to predict and manage the transducer's electrical response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct measurement methods like using a laser are used to measure transducer excursion, then measurement precision is improved, but device complexity and ease of manufacture deteriorate due to the need to open the transducer casing
Solution Approach 1:
The patent replaces direct mechanical/optical measurement methods (laser measurement requiring open casing) with an electrical measurement approach. An electrical model of the transducer is used to calculate excursion from electrical parameters (voltage, current, impedance) that can be measured through the sealed casing, thus maintaining manufacturing integrity while achieving measurement capability
Solution Approach 2:
The patent introduces an electrical model as an intermediary between the electrical signals and the mechanical excursion. Instead of directly measuring physical displacement, the system uses electrical measurements combined with an electrical model to indirectly determine excursion, avoiding the need to physically access the moving mass
2Power
If the transducer is driven to maximum excursion to elicit strong touch sensations, then the haptic effect intensity is improved, but the reliability deteriorates due to potential damage from repeated stop impacts
Solution Approach 1:
The patent implements a feedback control system where the electrical model continuously calculates the current excursion based on measured electrical parameters. This feedback information is used to adjust the drive signal in real-time, preventing the transducer from exceeding maximum excursion limits while still allowing operation at high intensity levels
Solution Approach 2:
The patent performs preliminary calculation of the electrical model to predict excursion before it actually occurs. By calculating the expected excursion from the drive signal parameters using the electrical model, the system can prevent damage before it happens rather than reacting after the transducer hits the stops
3Difficulty of detecting and measuring
If invasive measurement techniques are used to measure transducer excursion, then measurement capability is improved, but the ease of operation deteriorates due to the need to open and modify the transducer casing
Solution Approach 1:
The patent replaces mechanical measurement approaches (requiring physical access to the moving mass) with electrical measurement and calculation methods. Electrical parameters can be measured through the sealed casing, and the electrical model converts these measurements into excursion information without requiring any physical modification to the transducer assembly
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 effectively limits the transducer's electrical response to prevent damage by determining and adhering to a threshold excursion, ensuring the transducer operates within safe limits without the need for invasive measurement techniques, suitable for both production and end-product applications.
Implementation Method 1
The electromechanical force may be elicited by applying an input voltage (usually oscillatory) to the LRA which makes the inner mass of the LRA move
Implementation Method 2
The voltage and current across the terminals of the haptic transducer may be measured
Data Source
AI summary
Embodiments described herein relate to methods and apparatus for limiting the excursion of a transducer. The method comprises receiving a transducer signal; and limiting the transducer signal or a signal derived therefrom to generate a limited transducer signal for input into the transducer such that an electrical response caused by the limited transducer signal in an electrical model of the transducer would be less than a threshold electrical response, wherein the threshold electrical response has been determined by: inputting a stimulus input signal into the electrical model of the transducer, wherein the stimulus input signal is designed to cause the transducer to reach a maximum excursion; and determining the threshold electrical response as a maximum of the electrical response caused by the stimulus input signal in the electrical model of the transducer.