Mobile Platform Displacement Measurement Using Visual Markers
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Solution Overview
Problem
Current technologies for measuring displacement of Unmanned Aerial Vehicles (UAVs) are limited by height range, vulnerable to ambient interference, and unreliable in indoor or complex settings, particularly due to limitations in ultrasonic and GPS-based solutions.
Innovation Solution
A method and apparatus using an imaging device to acquire and match stereoscopic frames, combined with height and angle data from barometers, ultrasonic devices, and IMUs, to calculate displacement and velocity of a mobile platform, enabling accurate measurement across a wide range of heights and environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If GPS-based solution is used for displacement measurement, then measurement range is extended, but reliability deteriorates in indoor or complex ambient settings due to lack of reliable signal
Solution Approach 1:
The patent introduces visual markers as intermediary objects that mediate between the imaging device and the environment. These markers serve as reliable reference points that can be detected in indoor or GPS-denied environments, replacing the need for GPS signals while maintaining measurement capability.
Solution Approach 2:
The patent replaces the GPS-based electromagnetic signal system with a visual-based optical system using imaging devices and visual markers. This substitution enables operation in environments where GPS signals are unavailable by using visual features instead of radio frequency signals.
2Measurement precision
If ultrasonic device is used for displacement measurement, then measurement capability is achieved, but detective distance is limited to half meter to five meters
Solution Approach 1:
The patent replaces the ultrasonic acoustic measurement system with an optical imaging-based system. This substitution extends the measurement range from meters to potentially hundreds of meters while maintaining displacement measurement capability, as optical systems are not subject to the same distance limitations as ultrasonic devices.
Solution Approach 2:
The patent changes the fundamental measurement parameter from acoustic wave properties (ultrasonic) to optical image properties. By using visual markers and imaging devices, the system achieves extended range measurement capability while maintaining precision through image processing and feature matching techniques.
3Area of stationary object
If binocular imaging device is used for displacement measurement, then measurement range is extended to one to ten meters, but device complexity increases due to baseline requirement
Solution Approach 1:
The patent extracts the depth measurement capability from the complex binocular structure by using visual markers with known dimensions. Instead of requiring two lenses with a specific baseline, the system uses a single imaging device that captures images of markers with predetermined sizes, thereby achieving depth measurement without the complexity of binocular geometry.
Solution Approach 2:
The patent uses visual markers that are copies or representations of known geometric structures with predetermined dimensions. By recognizing these marker copies in the captured images, the system can infer distance and displacement information without requiring complex imaging hardware, thus reducing device complexity while maintaining measurement range.
4Measurement precision
If monocular imaging device with ultrasonic device is used for displacement measurement, then low altitude measurement is achieved, but vulnerability to ambient noises increases
Solution Approach 1:
The patent replaces the ultrasonic acoustic sensing subsystem with a purely optical imaging-based measurement system. This substitution eliminates vulnerability to ambient acoustic noises while maintaining low altitude measurement precision, as the visual marker recognition system is not affected by sound waves or acoustic interference.
Solution Approach 2:
The patent creates a universal measurement system that uses visual markers for both low altitude and high altitude measurements, replacing the need for separate ultrasonic and imaging systems. This multi-functional approach eliminates ambient noise vulnerability across the entire measurement range while maintaining precision through consistent visual feature recognition.
Data Source
AI summary
A method for detecting a displacement of a mobile platform includes acquiring a first frame and a second frame using an imaging device coupled to the mobile platform, obtaining an angle of the imaging device relative to a reference level while acquiring the first frame, and determining the displacement of the mobile platform based at least on the first frame, the second frame, and the angle of the imaging device relative to the reference level.