Electromagnetic Haptic Transducer Resonance Tracking and Force Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vibro-haptic transducers in portable devices face variations in resonance frequency due to sample-to-sample variations, device assembly changes, aging, and user interactions, making it challenging to efficiently generate consistent tonal vibrations for notifications.
Innovation Solution
A system that includes a signal generator and processing subsystem to monitor operating parameters of an electromagnetic load, determining applied force and adjusting the driving signal to maintain resonance frequency, allowing the transducer to function effectively as both an actuator and a force sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the resonance frequency is estimated using fixed parameters, then the initial design is simple, but the resonance frequency varies over time due to manufacturing variations, aging, and usage conditions
Solution Approach 1:
The patent implements dynamic tracking of resonance frequency by continuously monitoring the electrical characteristics (impedance, current, voltage) of the haptic transducer during operation. The system adapts the driving signal frequency in real-time to follow the actual resonance frequency, which changes due to manufacturing variations, aging, temperature, and usage conditions. This transforms the static resonance frequency estimation into a dynamic adaptation process.
Solution Approach 2:
The system employs feedback mechanisms by monitoring the electrical parameters of the transducer and using this information to adjust the driving signal. The controller observes changes in impedance, current, or voltage that indicate resonance conditions, and automatically adjusts the driving frequency to maintain optimal operation. This closed-loop feedback ensures consistent tonal vibrations despite parameter drift over time.
2Adaptability or versatility
If separate force sensors are added to detect user interactions, then force detection capability is improved, but device complexity increases
Solution Approach 1:
The patent makes the haptic transducer multi-functional by utilizing it both as an actuator to generate vibrations and as a sensor to detect force applied by the user. When force is applied to the transducer, it alters the electrical characteristics (impedance, resonant frequency, current draw) that the controller already monitors for vibration control. By analyzing these same electrical parameters, the system can detect both the presence and magnitude of applied force without adding separate sensing hardware.
Solution Approach 2:
The transducer serves itself by providing sensing capability inherent to its operation. The electrical characteristics that define its actuating behavior also contain information about external forces applied to it. The controller extracts force information from the same electrical measurements used to control vibration, allowing the transducer to simultaneously perform actuation and sensing functions through self-monitoring of its own electrical state.
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 consistent haptic feedback and reduces the need for mechanical buttons by utilizing the transducer as both an output device and an input force sensor, adapting to user interactions and maintaining efficient vibration generation.
Implementation Method 1
an electromagnetic load (e.g., a haptic transducer, a loudspeaker, a microspeaker)
Implementation Method 2
it may be desirable to operate the haptic actuator at its resonance frequency
Data Source
AI summary
A system for performing force sensing with an electromagnetic load may include a signal generator configured to generate a signal for driving an electromagnetic load and a processing subsystem configured to monitor at least one operating parameter of the electromagnetic load and determine a force applied to the electromagnetic load based on a variation of the at least one operating parameter.