Articulated Robot Deflection Measurement Using Optical Mark
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Solution Overview
Problem
Existing methods for determining the spring constant of joint axes and links in articulated robots are costly, require complex operations, and are difficult for operators to perform accurately, as they often necessitate the use of rotation angle sensors and weight attachment.
Innovation Solution
A deflection measurement system that includes a measured mark and a position measuring device, controlled by a control apparatus to calculate the actual deflection amount of the mechanism unit by changing the relative positional relationship between the mark and the device, allowing for the determination of the spring constant without the need for rotation angle sensors or weight attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If rotation angle sensors are attached to joint axes to measure actual rotation angles, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a measured mark as an intermediary object attached to the joint axis. Instead of directly measuring the rotation angle with a sensor on the axis, the system measures the position of this mark from a distant location using a position measuring device. This intermediary approach enables indirect measurement without requiring complex sensor installation on the joint axis itself.
Solution Approach 2:
The patent replaces the mechanical/physical sensor system (rotation angle sensor attached to the joint axis) with an optical measurement system (position measuring device capturing images of the measured mark from a distance). This substitution eliminates the need for direct mechanical coupling and complex sensor installation while achieving the same measurement objective.
2Measurement precision
If weights are attached to tip ends of robot arm units to measure deflection amounts, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent uses the position measuring device and measured mark as an intermediary measurement system. Instead of directly applying weights and measuring physical deflection, the system captures images of the measured mark at different robot postures and calculates deflection from the positional changes. This eliminates the need for physical weight attachment operations.
Solution Approach 2:
The patent replaces the mechanical weight-attachment method with an optical measurement approach. By using a position measuring device to capture the location of a measured mark and calculating deflection from coordinate changes, the system achieves deflection measurement without any physical weight attachment, thereby improving ease of operation.
3Manufacturing precision
If theoretical commanded positions are preliminarily determined for calculating spring constants, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent enables the system to self-determine the spring constant through automatic calculation based on measured data. By capturing images at different postures and computing deflection amounts from the positional changes of the measured mark, the system automatically derives the spring constant without requiring external theoretical position determination or complex preliminary setup procedures.
Data Source
AI summary
A measured mark is arranged on a link of an articulated robot. A camera for measuring a position of the measured mark is arranged at a position distant from the articulated robot. A control apparatus of the articulated robot changes posture of the articulated robot, measures positions of the measured mark respectively before and after a change of the posture by the camera, and calculates an actual deflection amount of the link based on a movement amount between the position of the measured mark measured before the change of the posture and the position of the measured mark measured after the change of the posture.