Parallel Robot Calibration Using Cardan Shaft Stop Initialization
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Solution Overview
Problem
Current handling devices, particularly parallel kinematic robots, require time-consuming and error-prone calibration processes that involve manual intervention, risking mechanical damage and inaccuracies due to the reliance on dial gauges and manual operation.
Innovation Solution
A method utilizing a length-variable and articulated cardan shaft as a movable drive connection between a stationary drive motor and the tool head, combined with motorized upper and lower arms, allows for precise calibration and initialization through load torque detection and sensor-driven angular positioning, eliminating the need for manual calibration and reducing personnel and time requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual calibration with dial gauges is used, then calibration can be performed, but the process is time-consuming and error-prone
Solution Approach 1:
The patent replaces the mechanical dial gauge measurement system with an optical sensor system that detects the position of the tool head or coupling element using light-based methods, eliminating manual reading errors and significantly reducing calibration time while improving measurement precision
Solution Approach 2:
The calibration system automatically determines the reference position by having the tool head or coupling element move to predefined positions and having sensors automatically detect and record these positions without requiring manual intervention or reading, making the calibration process self-executing
2Ease of operation
If manual calibration intervention is performed, then calibration can be completed, but mechanical damage risk increases
Solution Approach 1:
The system performs calibration automatically through program-controlled movements of the arms and automated sensor detection, eliminating the need for manual intervention that could cause mechanical damage, while maintaining ease of operation through simple activation
Solution Approach 2:
The sensor system continuously monitors the position of the tool head or coupling element during calibration movements and provides feedback to the control system, enabling precise control that prevents excessive movements or forces that could cause mechanical damage
3Manufacturing precision
If calibration is performed frequently, then positioning accuracy is maintained, but time loss increases
Solution Approach 1:
The automated optical sensor system performs calibration measurements much faster than manual dial gauge methods, reducing the time penalty of frequent recalibration while maintaining positioning accuracy through rapid, precise measurements
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 method enables reliable, reproducible, and precise calibration of handling devices, reducing the risk of mechanical damage and improving positioning accuracy without manual intervention, allowing for efficient recalibration of differently designed robots.
Implementation Method 1
load torques acting on the upper arm pivot axes are detected and the respective load torques acting on the at least two upper arms are compared
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
The invention relates to a method for calibrating a handling device (18), in particular a handling and/or parallel kinematics robot (24), comprising a tool head (28) suspended on at least two parallel kinematically movable arms (26), said tool head being also coupled to a rotary drive via a drive connection or cardan shaft (30). Each of the at least two arms (26) comprises an upper arm (36) that is motor-movable about a defined upper arm pivot axis (38) between two end positions, and a lower arm (40) that is pivotally mounted on the upper arm (36). By detecting load torques and/or angular positions, the upper arms (36) are brought into approximately matching angular positions. By simultaneous pivoting, the upper arms (36) are moved up to a boundary position, which is defined by a mechanical stop of the drive connection, which is movable independently of the upper arms (36), to the tool head (28), after which the tool head and/or the drive connection assigned thereto is/are distanced by a defined pivoting angle from the boundary position by moving the upper arms (36) back. One of the upper arms (36) is brought into one of the two end positions, and the angular position thus achieved is detected by sensors and is used for the position and/or angle initialization of the respective upper arm (36), after which the upper arm (36) is moved back again. Thereafter, a further upper arm (36) is brought into the same one of the two end positions as the other upper arm (36). The angular position thus achieved is detected by sensors and is used for the position and/or angle initialization of the affected upper arm (36).