Linear Resonant Actuator Damping Control via Induction Coil
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Solution Overview
Problem
Conventional linear resonant actuators suffer from residual vibrations due to low damping, which affects the haptic feedback and efficiency in stopping vibrations, and existing control methods are complex and prone to computational errors from temperature and component aging.
Innovation Solution
Incorporating an induction coil to generate a damping effect through feedback, allowing for controlled braking by adjusting the damping coefficient, which is achieved by positioning and winding the induction coil to obtain an induced voltage proportional to the vibration speed, and using a control system with a signal amplifier, excitation device, flow controller, and processing unit to manage the braking signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the linear resonant actuator uses low damping to obtain higher drive efficiency, then the drive efficiency is improved, but residual vibration occurs after excitation stops
Solution Approach 1:
The patent applies dynamic damping control by switching between different damping states. During excitation, low damping is maintained for high efficiency. After excitation stops, high damping is activated to quickly suppress residual vibrations. This dynamic adjustment of damping characteristics resolves the contradiction between drive efficiency and vibration suppression.
Solution Approach 2:
The patent uses periodic braking signals applied to the driving coil to suppress residual vibrations. The braking signal is applied in periodic cycles after excitation stops, creating controlled damping periods that rapidly reduce vibrations while maintaining overall system efficiency.
2Reliability
If the driving output is measured and BEMF is calculated to control vibration, then feedback control is achieved, but computational errors occur due to temperature and component aging
Solution Approach 1:
The patent implements feedback control by measuring the actual output current and voltage of the driver, calculating BEMF through the measurement circuit, and feeding this information back to the controller to adjust the output. This closed-loop feedback mechanism maintains control accuracy despite temperature variations and component aging.
Solution Approach 2:
The patent replaces physical sensors (Hall elements or accelerometers) with an electrical measurement approach. By measuring electrical parameters (current and voltage) and calculating BEMF, the system achieves position/acceleration detection without mechanical sensors, improving reliability and reducing computational errors.
3Measurement precision
If a Hall element or accelerometer is disposed in the linear resonant actuator for position/acceleration detection, then detection accuracy is improved, but device complexity and control system stability requirements increase
Solution Approach 1:
The patent replaces mechanical sensors (Hall elements or accelerometers) with an electrical measurement system. By measuring the back electromotive force (BEMF) through the measurement circuit and calculating position/acceleration from electrical parameters, the system achieves the same detection function without adding mechanical components, thereby reducing device complexity and control system stability requirements.
Solution Approach 2:
The driving coil serves multiple functions: it acts as both the actuator for generating vibration and as the sensor for detecting position/acceleration through BEMF measurement. This multi-functionality eliminates the need for separate sensing components, reducing overall system complexity while maintaining detection accuracy.
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 effectively reduces residual vibrations and improves the stopping time of the linear resonant actuator, enhancing the haptic feedback and stability of the control system while minimizing computational errors.
Implementation Method 1
the induction coil being fixed with respect to the vibrator... the induction coil and the driving coil may partially overlap... according to the induced voltage proportional to the vibration speed of the vibrator generated by the induction coil
Implementation Method 2
one or more driving coils being located at the periphery of the vibrator... the output of the driver is cut off intermittently by the controller to measure the BEMF of the driving coil... calculating the BEMF of the linear resonant actuator through the measurement circuit
Data Source
AI summary
The invention discloses a control system for LRA, applicable to an LRA having a speed sensing coil. The control system comprises a signal amplifier, an excitation device, a flow controller, a processing unit, and a driver. The processing unit is connected to the signal amplifier, the excitation device and the flow controller, so as to stop output, output the excitation signal as a driving signal or process the induction signal from the signal amplifier into an appropriate system damping coefficient and output as a driving signal when the flow controller outputs a stop, excitation or braking state signal, respectively.