Manipulator Calibration Using Low Thermal Deformation Measuring Apparatus
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Solution Overview
Problem
Manipulators, such as industrial robots, experience positional inaccuracies due to thermal expansion and mechanical changes, leading to deviations in tool positioning despite identical joint positions, which existing measurement methods struggle to accurately compensate for.
Innovation Solution
A measuring apparatus with a measuring body, preferably spherical or cubic, featuring low thermal deformation and equipped with sensors and markers, is used to determine precise positions relative to a fixed reference point, allowing for both relative and absolute measurements to calibrate the manipulator's kinematics and compensate for thermal and mechanical changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a manipulator performs repeated movements to the same joint positions, then the tool should occupy the same position, but thermal expansion causes the tool to deviate from the theoretical position
Solution Approach 1:
The patent applies parameter changes by using a measuring apparatus to detect actual positional deviations caused by thermal expansion and mechanically changing the manipulator model parameters (position parameters) to compensate for these deviations. The system continuously updates the model parameters based on measured data, allowing the manipulator to adapt to thermal effects and maintain positioning accuracy despite temperature changes.
2Measurement precision
If existing measurement methods are used to register manipulator positions, then calibration can be performed, but measurement precision is insufficient to accurately compensate for thermal and mechanical changes
Solution Approach 1:
The patent replaces conventional mechanical measurement methods with an optical measurement system. The measuring apparatus uses optical sensors and detection methods to register the positions of measuring points on the manipulator, achieving higher measurement precision. This optical substitution enables accurate detection of small positional deviations caused by thermal expansion, providing sufficient data precision for effective compensation.
3Manufacturing precision
If the manipulator model parameters are adjusted based on imprecise measurements, then calibration is performed, but the positioning accuracy does not improve sufficiently
Solution Approach 1:
The patent implements a feedback mechanism where the measuring apparatus continuously monitors the manipulator's actual positions and feeds this information back to update the manipulator model parameters. The measured position data is used to calculate deviations from the theoretical model, and these deviations are used to adjust the model parameters iteratively. This closed-loop feedback ensures that the model parameters are continuously refined based on high-precision measurement data, achieving accurate positioning compensation.
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
The solution enables precise calibration of manipulator models, reducing positional errors and improving the accuracy of robot movements by accounting for thermal and mechanical deformations, thereby enhancing the precision and efficiency of robot operations.
Implementation Method 1
The measuring body exhibits only slight thermal deformation, in particular a longitudinal coefficient of expansion a less than or equal to 10·10−6/K
Implementation Method 2
a position is determined, in particular a distance relative to a reference point fixed in relation to a manipulator, such as for example a reflecting mark, for example a retroreflector
Data Source
AI summary
A measuring apparatus (1; 1′) for measuring a manipulator (10), with a measuring body (2; 2′) having at least one measurement point (3; 3′) that is fixed in relation to the measuring body for determining a position (TTCP,3; TTCP,3′) relative to a reference point (TCP) that is fixed in relation to the manipulator, and an attaching device connected to the measuring body (2) for fixing on the surroundings, includes at least one calibration point (7; 7′) connected to the measuring apparatus for determining a position (TR, M; TR,M′) relative to the surroundings and/or at least one measurement point (6) positioned on the attaching device.