Laser Projector Alignment with Camera and IMU Feedback
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Solution Overview
Problem
Existing light projection systems face challenges in aligning the projector to the environment for precise positioning and orientation of projected templates, particularly in environments without retroreflective or cooperative targets.
Innovation Solution
The system employs a light projector with integrated cameras and inertial measurement units to automatically or semi-automatically align itself to the environment, using image processing techniques to register with electronic models or point clouds, and includes mechanisms for drift correction and realignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional light projection systems are used without retroreflective targets, then the system can operate in more environments, but the alignment precision and positioning accuracy deteriorate
Solution Approach 1:
The patent introduces an intermediary alignment system consisting of cameras and inertial measurement units (IMUs) that mediate between the projector and the environment. The cameras capture images of the environment while the IMUs provide motion data, and these intermediaries work together to compute alignment transformations, enabling precise positioning without requiring retroreflective targets.
Solution Approach 2:
The patent replaces the traditional mechanical/optical alignment system (which relies on retroreflective targets and manual adjustment) with an electronic computation system. The alignment is achieved through image processing algorithms that combine camera images with IMU data to calculate transformation matrices, substituting physical alignment mechanisms with computational methods.
2Device complexity
If manual alignment methods are used, then the system structure can be simpler, but the alignment time and operational complexity increase
Solution Approach 1:
The system performs preliminary actions by continuously capturing environment images and IMU data before projection operations are needed. The alignment computation is performed in advance and continuously updated, so when projection begins, the alignment is already established, eliminating time-consuming manual alignment procedures.
Solution Approach 2:
The alignment system is self-service in that it automatically performs alignment computations using its own integrated sensors and processors. The projector's embedded system continuously processes camera images and IMU data to self-correct its position and orientation, eliminating the need for external operators to perform manual alignment adjustments.
3Ease of operation
If the projector is moved or rotated during operation, then the system becomes more flexible, but the alignment accuracy deteriorates due to drift
Solution Approach 1:
The system implements continuous feedback by monitoring IMU data and camera images throughout operation. When the projector moves or rotates, the IMUs detect the motion and the cameras capture the new environment perspective, and this feedback is fed into the alignment computation to update the transformation matrices, maintaining accuracy despite movement.
Solution Approach 2:
The alignment system is designed to be dynamic rather than static. The transformation matrices are continuously updated based on real-time IMU and camera data, allowing the system to adapt to changes in projector position and orientation. This dynamic approach enables the projector to be moved and rotated during operation while maintaining alignment accuracy.
Data Source
Figure 1A~1C
Figure 1D
Figure 2A
AI summary
A light projector and method of aligning the light projector is provided. A light projector steers an outgoing beam of light onto an object, passing light returned from the object through a focusing lens onto an optical detector. The light projector may generate a light pattern or template by rapidly moving the outgoing beam of light along a path on a surface. To place the light pattern/template in a desired location, the light projector may be aligned with an electronic model.