Multi-Mode Strain Gauge Button Sensing for Low-Power Haptics
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Solution Overview
Problem
Modern consumer electronics face challenges with buttons that exhibit mechanical non-idealities such as friction, stiffness, and aging, leading to undesired behaviors like delay, non-linearities, and false presses, which are not optimally addressed by existing closed-loop control systems due to high power usage and bandwidth requirements.
Innovation Solution
A button design incorporating force sensors and a haptic engine with control circuitry that operates in multiple modes, allowing for low-power detection of user force and high-resolution haptic feedback, switching between a low sampling rate mode for power savings and a high sampling rate mode for feedback, using a sensor topology that supports both high-speed closed-loop control and passive scan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If closed-loop control is implemented to address mechanical non-idealities, then button performance is improved, but power consumption increases
Solution Approach 1:
The system dynamically switches between two operational modes: a low-power detection mode with reduced sampling rate, and a high-performance closed-loop control mode with higher sampling rate. This dynamic adaptation allows the button to achieve high reliability when needed while conserving power during normal operation, directly resolving the contradiction between button performance and power consumption.
2Speed
If high sampling rate mode is used for feedback, then sensing speed is improved, but power consumption increases
Solution Approach 1:
The system employs periodic sampling at different rates depending on operational requirements. During normal operation, a lower sampling rate is used to conserve power. When user interaction is detected or haptic feedback is required, the system transitions to a higher sampling rate mode, providing fast sensing speed only when necessary, thus resolving the contradiction between sensing speed and power consumption.
3Use of energy by moving object
If low sampling rate mode is used for power savings, then power consumption is reduced, but feedback resolution is lost
Solution Approach 1:
The system dynamically adjusts sampling rate based on operational context. During passive scanning and normal operation, a low sampling rate conserves power. When user press is detected or closed-loop haptic feedback is activated, the system switches to a high sampling rate mode, ensuring high measurement precision and feedback resolution are maintained when needed, thus resolving the contradiction between power consumption and feedback resolution.
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 design achieves lower power consumption, higher maximum sensing speed, and maintains high-resolution feedback without information loss, improving user interaction by mitigating mechanical non-idealities.
Implementation Method 1
A button includes a set of force sensors and a haptic engine
Data Source
AI summary
A device includes a button, a set of force sensors coupled with the button, a haptic engine coupled to with the button, and control circuitry, where the control circuitry is configured to control operation of the device according to a first mode of operation during a first time duration to detect user force applied to the button via signals from the set of force sensors, and control the device according to a second mode of operation during a second time duration for closed loop control of haptic feedback to the button via the haptic engine and the set of force sensors.