Industrial Robot Tool Center Point Calibration Using Angled Light Barriers
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Solution Overview
Problem
Industrial robots face challenges in precisely calibrating the tool center point due to tool wear and bending, which leads to defective positioning, and existing methods require complex coordinate transformations and time-consuming searches for the crossing point.
Innovation Solution
A method using angled light barriers that cross at a vertex angle greater than zero, allowing the tool tip to interrupt the barriers to record actual TCP positional coordinates, determine deviations from desired coordinates, and calculate the tool center point deviations for each axis, eliminating the need for a crossing point search and simplifying the calibration process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multistage movement operations and coordinate transformations are used for calibration, then the tool center point can be calibrated, but the calibration process becomes complex and time-consuming
Solution Approach 1:
The patent replaces complex mechanical coordinate transformation operations with an optical measurement system. Light barriers optically detect the tool tip position directly in the base coordinate system, eliminating the need for mechanical multistage movements and mathematical coordinate transformations between different reference frames.
Solution Approach 2:
The patent introduces light barriers as an intermediary measurement medium between the tool and the calibration system. These light barriers serve as a mediator that directly provides positional information in the base coordinate system, avoiding the need for intermediate coordinate system transformations.
2Measurement precision
If traditional calibration methods with reference tips are used, then TCP positional coordinates can be determined, but extensive searching for the crossing point is required
Solution Approach 1:
The patent replaces the mechanical searching process for locating the crossing point with an optical detection system. The light barriers automatically detect when the tool tip reaches the calibration position through optical interruption, eliminating the time-consuming mechanical searching operation.
Solution Approach 2:
The calibration system performs self-positioning through the light barriers. When the tool tip moves through the calibration space, the light barriers automatically detect the position and provide feedback, eliminating the need for manual or iterative searching operations.
3Measurement precision
If complicated coordinate transformations are performed, then TCP positional coordinates can be calculated, but the calculation complexity increases
Solution Approach 1:
The patent replaces complex mathematical coordinate transformation calculations with direct optical measurement. The light barriers provide tool tip position data directly in the base coordinate system through optical detection, eliminating the need for mathematical transformations between coordinate systems.
Solution Approach 2:
The patent extracts the essential measurement function from the complex coordinate transformation process. By using light barriers to directly measure position in the base coordinate system, the patent removes the unnecessary intermediate coordinate transformation steps while retaining the essential calibration function.
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 enables precise and efficient calibration of the tool center point by directly determining deviations and correcting TCP positional coordinates, reducing the complexity of coordinate transformations and improving calibration speed.
Implementation Method 1
at least two light barriers which are angled to one another with a vertex angle a greater than zero in each case and cross one another at a crossing point
Data Source
AI summary
A method for calibration of a working point (TCP) for tools on industrial robots with a calibration device includes the use of at least two light barriers with an azimuth angle (α) greater than zero at an angle to each other and intersecting at an intersection point. The method includes fixing set TCP positional coordinates for a set working point for the tool, relative to a tool reference point and a TCP coordinate system relative to the working point, moving the tool to the set working point with relation to the TCP coordinate system through the light barriers, such that the tool tip interrupts the light barriers, recording actual TCP positional coordinates determining the difference between the set TCP positional coordinates for the interruption of the light barriers for a set working point and the corresponding recorded actual TCP positional coordinates for the actual working point, calculating the actual working point from the set working point for the number of levels of light barriers from the differences and the known position and azimuth angles (a) of the light barriers.