MEMS Reflector Trajectory Control via Differential Mode Oscillation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
MEMS reflectors in LIDAR systems face a trade-off between field-of-view width and measurement resolution, with existing technologies either requiring high resolution at narrow fields-of-view for long distances or large fields-of-view with lower resolution for nearby environments, and struggle to control measurement resolution within specific sectors of the field-of-view effectively.
Innovation Solution
A MEMS reflector system where a central reflector is attached to a mobile frame, oscillating in common and differential modes at specific resonance frequencies, allowing the angular velocity to be altered in selected sectors of the field-of-view by driving the reflector and frame with sinusoidal voltages where the differential mode frequency is a second or third harmonic of the common mode frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a simple sine wave scanning pattern is used, then the scanning mechanism is simple, but the measurement resolution is uneven with data clustering at the edges of the field-of-view
Solution Approach 1:
The patent applies dynamics by transitioning from a static sine wave scanning pattern to a dynamic scanning pattern that utilizes both common mode and differential mode oscillations. The differential mode oscillation modifies the scanning trajectory in real-time to achieve uniform data distribution across the field-of-view, resolving the contradiction between simple operation and uniform measurement precision.
Solution Approach 2:
The patent changes the scanning parameters by introducing differential mode oscillation frequency as a controllable parameter. By adjusting the differential mode frequency relative to the common mode frequency, the system optimizes the scanning trajectory to achieve uniform angular velocity and even data distribution, thereby improving measurement resolution uniformity while maintaining operational simplicity.
2Measurement precision
If high measurement resolution is achieved across the entire field-of-view, then the resolution is improved, but the field-of-view width must be narrowed
Solution Approach 1:
The patent uses dynamic scanning patterns generated by combining common mode and differential mode oscillations to achieve high measurement resolution across a wide field-of-view. The differential mode oscillation allows the system to spend more time in regions requiring higher resolution while maintaining overall wide coverage, thus resolving the trade-off between resolution and field-of-view width.
Solution Approach 2:
The patent employs periodic differential mode oscillation superimposed on the common mode scanning to create a scanning pattern that periodically revisits and refines measurements across the field-of-view. This periodic action ensures high measurement resolution is achieved throughout the entire wide field-of-view rather than being concentrated in a narrow sector.
3Productivity
If the angular velocity is increased to scan larger areas, then the field-of-view coverage is improved, but the measurement resolution in specific sectors deteriorates
Solution Approach 1:
The patent applies local quality by using differential mode oscillation to create locally varied scanning velocities. The combined oscillation patterns cause the reflector to move slower in specific sectors where higher measurement resolution is needed, while maintaining faster overall scanning speed for wide field-of-view coverage. This resolves the contradiction between scanning speed and sector-specific 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 approach enables increased measurement resolution in selected parts of the field-of-view for both one-dimensional and two-dimensional scanning, improving data density and resolution without the trade-off between field-of-view width and measurement resolution.
Implementation Method 1
drive the mobile mass system into oscillating resonance tilt motion about the first axis... a first drive signal component with a first drive signal frequency and a first drive signal phase which correspond to common mode resonance oscillation... a second drive signal component with a second drive signal frequency and a second drive signal phase which correspond to differential mode resonance oscillation
Data Source
Figure 1~2
Figure 3a~3b
Figure 3c~5
AI summary
A scanning microelectromechanical reflector system comprising a mobile reflector mass and a mobile frame mass which surrounds the mobile reflector mass when the reflector plane coincides with the mobile frame plane. The mobile frame mass is suspended from a fixed frame which at least partly surrounds the mobile frame mass when the mobile frame plane coincides with the fixed frame plane. The reflector system further comprises a pair of first torsion beams aligned on a first axis in the mobile frame plane, and one or more first actuation units which can be configured to rotate the reflector mass and the mobile frame mass about the first axis.