Position Measuring System Using Back Surface Markers
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Solution Overview
Problem
Existing position measurement systems face challenges in accurately measuring the three-dimensional position of an object, particularly when the object rotates or moves behind obstacles, as markers may go out of the image-taking range, leading to incomplete data and inaccurate calculations.
Innovation Solution
A position measuring system comprising a marker set with three or more basic markers attached to a second area of an object, an image-taking device with a two-dimensional element, and a processing device that calculates the three-dimensional position of an acting portion using the determined position and angle of the marker set, ensuring the markers remain within the image-taking range even during rotational motions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If markers are attached to the object for position measurement, then the three-dimensional position can be calculated, but the markers may go out of the image-taking range when the object rotates or moves behind obstacles
Solution Approach 1:
The patent attaches markers to a two-dimensional surface (the back surface of the front arm) rather than distributing them throughout three-dimensional space. This dimensional constraint ensures that all markers remain within the image-taking range as long as the image-taking device can capture the marked surface, eliminating the problem of markers going out of range during rotation or movement.
Solution Approach 2:
The marked surface serves multiple functions: it acts as both the attachment area for the markers and the imaging target. By making the second area (back surface) the marker attachment area, the system ensures that the markers remain within the image-taking range while still providing accurate position measurement data for the acting portion.
2Measurement precision
If markers are attached to the front surface near the acting portion, then accurate position measurement is achieved, but the markers may be obscured by the object itself during certain movements
Solution Approach 1:
Instead of attaching markers to the front surface (where the acting portion is located), the patent inverts the approach by attaching markers to the back surface of the front arm. This inversion eliminates self-obstruction because the markers are now on the opposite side of the object, visible to the image-taking device without being blocked by the object's own structure.
3Reliability
If the marker set is attached to a distant area from the acting portion, then markers remain visible, but the position calculation accuracy decreases
Solution Approach 1:
The patent applies local quality by specifically designating the back surface of the front arm (second area) as the marker attachment area. This location provides an optimal balance: it is close enough to the acting portion to maintain measurement accuracy, yet positioned such that markers remain consistently visible to the image-taking device during normal operation.
Data Source
AI summary
A position measuring system includes a marker set having three or more basic markers that are known in positional relation and attached to a second area of an object which contains a first area having an acting portion and the second area continuous with the first area, an image-taking device having a two-dimensional image-taking element that takes an image of the marker set, a recording device that records the coordinate of the acting portion with respect to the marker set, and a processing device that calculates the three-dimensional position of the acting portion by using the position and angle of the marker set determined on the basis of the image of the marker set taken by the image-taking device and the coordinate of the acting portion with respect to the marker set that is recorded in the recording device.