Varifocal Lens Autofocus for Single-Camera 3D Trajectory Tracking
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Solution Overview
Problem
Current visual object tracking methods primarily focus on two-dimensional image plane tracking, limiting their application scenarios, and existing three-dimensional trajectory tracking methods rely on complex and costly stereo vision equipment with limited range.
Innovation Solution
An electro-hydraulic varifocal lens-based method for tracking a three-dimensional (3D) trajectory of an object using a mobile robot, which involves calibrating and modeling the varifocal lens, autofocusing on the object, and using visual simultaneous localization and mapping (V-SLAM) to track the object's 3D trajectory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stereo vision methods (binocular camera, multiple cameras, depth cameras, laser radars) are used to achieve 3D trajectory tracking, then depth information can be recovered, but the structure becomes complex and equipment cost increases
Solution Approach 1:
The patent extracts and utilizes only the necessary depth information from the varifocal lens focusing process, rather than employing complete stereo vision systems. By taking out the essential depth measurement capability and implementing it through a single camera with varifocal lens, the solution achieves 3D trajectory tracking without the structural complexity of multiple cameras or depth sensors
Solution Approach 2:
The patent replaces the mechanical/optical systems of stereo vision (multiple cameras, binocular setup) with an electro-optical system (single camera with varifocal lens controlled by electric current). The focusing control current serves as the control mechanism, substituting the mechanical alignment and calibration required in stereo vision systems
2Measurement precision
If depth cameras or laser radars are used for 3D tracking, then depth information can be obtained, but the tracking range is limited
Solution Approach 1:
The patent employs a dynamic varifocal lens that can adjust its focal length continuously through focusing control current. This dynamic adjustment capability allows the system to maintain focus and accurate depth measurement across varying distances, thereby extending the effective tracking range compared to fixed-focus depth cameras or laser radars with limited operational distances
3Device complexity
If a single camera is used for tracking, then the system is simpler and more cost-effective, but depth information is lost during camera projection
Solution Approach 1:
The patent implements a feedback mechanism where the focusing control current applied to the varifocal lens is used as depth information. By monitoring and utilizing the current required to achieve focus at different object distances, the system recovers depth information that would otherwise be lost in single-camera projection, while maintaining system simplicity
Solution Approach 2:
The patent changes the operational parameter of the camera system by introducing a varifocal lens with electrically controllable focal length. This parameter change enables the single camera to capture depth information through focusing adjustments, transforming a 2D imaging system into one capable of 3D trajectory tracking without adding complex hardware
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 method allows for cost-effective and efficient tracking of a 3D trajectory using a single camera, maintaining object focus and improving the stability and robustness of the object tracking and V-SLAM algorithms.
Implementation Method 1
electro-hydraulic varifocal lens-based method
Data Source
AI summary
The present disclosure discloses an electro-hydraulic varifocal lens-based method for tracking a three-dimensional (3D) trajectory of an object by using a mobile robot. By modeling an optical imaging system, a functional relation between a focusing control current of an electro-hydraulic varifocal lens and an optimal imaging object distance is obtained. Based on this functional relation, depth information of the object in focus with respect to a mobile robot camera and an average velocity of the objective within a time interval with respect to a previous moment can be obtained. With this information, 3D coordinates and motion trajectory of the object in a camera coordinate system can be calculated. At the same time, the mobile robot locates positions and attitudes in a world coordinate system in real time, and transforms the 3D coordinates of the tracked object from the camera coordinate system to the world coordinate system.