Robot Arm Tool Calibration Using Optical Beam Intersection
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Solution Overview
Problem
Conventional calibration methods for robotic arms with tool modules suffer from low accuracy due to contact calibration devices, wear of measuring boards, and aging of return springs, leading to reduced precision in determining the offset relationship between the tool center point and the robot arm.
Innovation Solution
A calibration device with an image recognition pattern and optical sensing devices forms a light intersection point, allowing for automatic calculation of actual coordinates of the machine tool relative to the robot arm's end point, eliminating the need for manual alignment and enhancing precision by using transfer matrices to connect visual and physical coordinate systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact calibration devices are used for tool center point calibration, then the calibration process can be performed, but the accuracy is reduced due to installation errors, measuring board wear, and return spring aging
Solution Approach 1:
The patent replaces the mechanical contact calibration system with an optical sensing system. Instead of using physical measuring boards and contact-based calibration devices that wear out and lose accuracy, the invention uses optical transmitters and receivers to detect the position of the tool center point through light beams, eliminating mechanical wear and installation errors
Solution Approach 2:
The patent creates an optical copy of the calibration target (the ball at the tool center point) by using optical transmitters to project light beams and optical receivers to detect their position. This optical copying method replaces the need for physical contact with measuring boards, allowing for non-contact, wear-free measurement
2Measurement precision
If manual alignment is used in calibration process, then the process can be completed, but human error reduces the precision of alignment between vision system and robot arm
Solution Approach 1:
The patent implements self-service calibration by having the robot arm automatically move the tool to intersect with optical beams detected by the vision system. The system autonomously calculates the tool center point position and performs calibration without requiring manual alignment operations, eliminating human error while maintaining ease of operation
Solution Approach 2:
The patent uses feedback from the optical sensing system to guide the calibration process. The optical receivers detect the position of light beams, provide feedback to the control system, which then commands the robot arm to adjust its position until the tool center point aligns with the detected position, achieving precise alignment through automated feedback control
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 improves the accuracy and reliability of tool center point calibration by automating the process and reducing human error, providing precise alignment without the limitations of conventional contact calibration methods.
Implementation Method 1
an optical transmitter to transmit an optical beam and an optical receiver to receive the optical beam
Data Source
Figure 1
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Figure 2B
AI summary
A calibration device is provided. The calibration device includes a frame, a first optical sensing device, a second optical sensing device and a third optical sensing device. The frame includes a bottom plate and at least four sidewalls, wherein the sidewalls have a first grating hole, a second grating hole, a third grating hole and a fourth grating hole at a first height. The bottom plate has an image recognition pattern, a first measurement point, a second measurement point and a third measurement point.