MEMS Actuator Controller Resonance Suppression
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Solution Overview
Problem
Existing controllers for micromechanical actuators, such as MEMS mirrors, require high system bandwidth and computing power, leading to complex and costly implementations, and struggle to avoid exciting spurious modes that degrade image quality in projector systems.
Innovation Solution
A modular multi-feedback controller structure with four linear controller elements: filtering and attenuating predefined frequency modes, minimizing mode quality, minimizing signal deviation, and rotating phase to suppress resonance modes, allowing for simpler integration and reduced bandwidth requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional controllers are used to actuate micromechanical actuators, then the actuators can be controlled, but the system requires high bandwidth and computing power leading to complex and costly implementations
Solution Approach 1:
The controller is divided into four distinct linear controller elements (first through fourth controller elements), each performing a specific function: filtering reference signal, modifying measuring signal, minimizing deviation, and phase rotation. This segmentation allows each element to be simpler while collectively achieving the required control accuracy without needing high overall system bandwidth.
Solution Approach 2:
The controller uses a feedback mechanism where the measuring signal (denoting recorded response by the actuator) is continuously processed through the four controller elements and fed back to adjust the control signal. This closed-loop feedback allows accurate control with linear elements rather than requiring high-bandwidth open-loop control.
2Reliability
If conventional controllers are used to actuate micromechanical actuators, then the actuators can be controlled, but high computing power is required leading to costly implementations
Solution Approach 1:
The patent replaces complex computational control algorithms with a structured approach using four linear controller elements that perform simpler mathematical operations (filtering, signal modification, deviation minimization, and phase rotation). This substitution reduces the computing power requirements while maintaining control accuracy.
3Productivity
If sawtooth signal is used to actuate MEMS mirror in quasi-static mode, then the mirror can be controlled line-by-line, but resonance modes may be excited degrading image quality
Solution Approach 1:
The controller explicitly identifies and targets the harmful resonance modes (particularly the first mode) and converts this knowledge into a benefit by designing the four controller elements to specifically filter and minimize these frequency components. The measuring signal is modified to minimize the quality of the first mode, and the phase rotation is applied at predefined frequencies corresponding to resonance modes, thereby eliminating the harmful effect while maintaining productive line-by-line operation.
Solution Approach 2:
The controller changes the parameters of the control signal by filtering predefined frequency modes from the reference signal, modifying the measuring signal to minimize mode quality, and rotating the phase at predefined frequencies. These parameter changes ensure that resonance modes are not excited while maintaining the line projection capability.
Data Source
AI summary
A controller for a micromechanical actuator, and corresponding actuating system, micro-mirror system and method, including a first input for a reference signal, a second input for a measuring signal denoting a recorded response to a control signal, a first controller element to filter/attenuate predefined frequency modes and/or predefined frequency components in the received reference signal and to output a filtered/attenuated reference signal, a second controller element to modify the received measuring signal to minimize the quality of the first/further modes by processing the received measuring signal and to output a modified measuring signal, a third controller element to minimize deviation between the filtered/attenuated reference and received measuring signals and to output a minimized reference signal, a fourth controller element to rotate the phase of the difference between the minimized reference and modified measuring signals for at least one predefined frequency and to transmit the modified reference as the control signal.