Dual-Loop Haptic Driver Circuitry for Impedance Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing driver circuitry for electromechanical loads, such as linear resonant actuators, lacks precise control over mechanical performance, particularly in haptic systems, where accurate control of vibrations and tactile sensations are crucial, due to limitations in adjusting output impedance to match target impedance values.
Innovation Solution
The implementation of driver circuitry that digitally determines an adjustment signal based on a digital reference signal, allowing the drive output signal to behave as if the output impedance has been adjusted to a target impedance, using a higher sample rate for precise control over a wide bandwidth, enabling improved mechanical control and haptic feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If driver circuitry uses conventional output impedance control methods, then the circuit structure remains simple, but the mechanical control accuracy and haptic feedback precision deteriorate
Solution Approach 1:
The patent replaces conventional analog impedance matching circuits with a digital signal processing approach. A digital filter processes the drive signal to compensate for output impedance variations, eliminating the need for complex analog impedance control circuitry while achieving superior mechanical control accuracy. The digital filter coefficients are calculated based on the electromechanical load characteristics, enabling precise control without additional hardware complexity.
Solution Approach 2:
The patent introduces a digital filter as an intermediary between the drive signal source and the electromechanical load. This digital filter acts as a mediator that compensates for output impedance effects by processing the drive signal in the digital domain, thereby achieving accurate mechanical control without directly modifying the physical impedance characteristics of the driver circuitry.
2Speed
If driver circuitry operates at low sample rate, then the processing speed and bandwidth are limited, but the computational complexity and power consumption are reduced
Solution Approach 1:
The patent implements a dynamic sampling strategy where the sample rate is adaptively adjusted based on the frequency content and control requirements of the haptic signal. During transient haptic events requiring precise control, the sample rate increases to capture fast dynamics. During steady-state periods with lower control demands, the sample rate decreases to reduce computational load and power consumption, thereby optimizing the trade-off between processing speed and energy usage.
3Reliability
If driver circuitry implements precise impedance matching, then the haptic feedback quality improves, but the control system complexity increases
Solution Approach 1:
The patent replaces complex analog impedance matching networks with digital signal processing. A digital filter is designed with coefficients that compensate for the driver circuitry's output impedance characteristics. This digital approach achieves precise haptic feedback control without requiring complex analog circuitry, thereby improving haptic feedback quality while maintaining relatively simple system architecture.
Solution Approach 2:
The patent changes the control parameters from direct impedance matching to frequency-domain filter coefficient adjustment. By transforming the control problem into the digital signal processing domain, the system achieves precise haptic feedback through software-based parameter optimization rather than hardware-based impedance matching, reducing overall system complexity.
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 solution enhances the accuracy and adaptability of mechanical control, allowing for crisp haptic effects, wide bandwidth operations, and consistent performance across varying conditions, thereby improving the user experience in haptic systems.
Implementation Method 1
An AC voltage signal (a drive signal) is used to drive the voice coil, which is arranged to magnetically couple with the moveable magnetic mass. When the voice coil is driven with the AC voltage signal (particularly at the resonant frequency of spring-mass arrangement), the resultant magnetic field induces movement in the magnetic mass and causes it to vibrate with a human-perceptible force.
Data Source
AI summary
Driver circuitry for driving an electromechanical load with a drive output signal, the driver circuitry comprising: a first control loop operable to control the drive output signal based on a drive input signal; and a second control loop operable to control the drive output signal based on a current flowing through and/or a voltage induced across the electromechanical load, wherein the second control loop is configured to have a lower latency than the first control loop, and to control the drive output signal to compensate for an impedance of the electromechanical load.