Robot Calibration in Shared Machine Tool Workspaces
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Solution Overview
Problem
The cooperation between robots and machine tools is hindered by the design-related lower accuracy of robot mechanics, necessitating time-consuming and expensive calibration methods, which are typically performed only during commissioning and fail to address errors that accumulate over the operational lifetime.
Innovation Solution
A method where the robot's working space overlaps with the machine tool's space, allowing for rapid and repeated calibration by comparing and correcting position values using the machine tool as a measuring standard, especially at critical points, without requiring 3D measuring means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods using optical measuring devices are employed, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a laser tracker as an intermediary measuring device that bridges the robot coordinate system and the machine tool coordinate system. The laser tracker measures the position of a target attached to the robot flange, providing precise measurement data without requiring complex optical measuring devices integrated into the robot or machine tool itself. This intermediary approach achieves high calibration accuracy while keeping the overall system complexity manageable.
2Measurement precision
If comprehensive calibration is performed during commissioning, then initial measurement precision is improved, but loss of time occurs during operational lifetime due to accumulated errors
Solution Approach 1:
The patent implements periodic calibration by enabling quick recalibration during operational lifetime. The laser tracker-based measurement system allows for relatively fast measurement of the robot's position at multiple points, and the coordinate system transformation can be rapidly recalculated. This periodic recalibration approach corrects accumulated errors without requiring extensive downtime, balancing measurement precision maintenance with minimal loss of operational time.
3Productivity
If robot mechanics are designed for higher speed and flexibility, then productivity is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent implements a feedback-based calibration approach where the laser tracker continuously measures the actual position of the robot flange, and these measurements are used to calculate transformation parameters that correct positioning errors. The system establishes a coordinate system transformation between the robot coordinate system and the machine tool coordinate system based on measured data, providing continuous feedback correction that enables high-speed robot operation while maintaining manufacturing precision through dynamic error compensation.
Data Source
AI summary
A method for calibrating a robot is disclosed. A working space of the robot at least partly overlaps with a working space of a machining and/or production tool. The robot is moved such that a reference point of the robot is at a first position within the working space of the machining and/or production tool. A first position value for the robot at the first position is compared with a first position value for the machining and/or production tool at the position. If the first position value for the robot differs from the first position value for the machining and/or production tool, the first position value for the robot is corrected or the first position value for the machining and/or production tool is corrected such that the first position value for the robot and the first position value for the machining and/or production tool are the same.