Five-Axis Delta Robot Calibration Without Arm Disassembly
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Solution Overview
Problem
Calibrating complex and heavy delta robots with more than three axes is time-consuming and complicated, and existing methods are not suitable for all designs, especially when additional axes need to be calibrated.
Innovation Solution
A method for calibrating a five-axis delta robot involves executing arm movements and tilting movements while locking specific axes, using a measurement device to compare movements and determine calibration errors, allowing for the precise calibration of the fourth and fifth axes by analyzing deviations in parallelism or other defined relationships between driving links and the tilting body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the delta robot is disassembled by detaching driven links from driving links for calibration, then calibration can be performed on traditional three-axis delta robots, but the process becomes complicated, troublesome and time consuming for complex and heavy delta robots with more than three axes
Solution Approach 1:
The calibration process is segmented into two independent parts: (1) calibration of the three translation axes using the existing disassembly method, and (2) calibration of the rotation and tilting axes using a separate method with a measurement device attached to the tilting body. This segmentation allows the heavy manipulator arms to remain assembled while still enabling comprehensive calibration of all five axes.
Solution Approach 2:
A measurement device is introduced as an intermediary element attached to the tilting body to measure positions and orientations during calibration. This intermediary enables indirect measurement of the rotation and tilting axes without requiring disassembly of the manipulator arms, thus saving time while maintaining calibration accuracy.
2Measurement precision
If the delta robot is disassembled for calibration, then calibration can be performed on traditional designs, but this method cannot be carried out on delta robots with different designs and cannot calibrate additional axes
Solution Approach 1:
The calibration method is designed to be universal and applicable to delta robots with different designs and configurations. The measurement device can be attached to the tilting body regardless of the specific robot design, and the calibration procedure can handle both traditional three-axis delta robots and newer five-axis or six-axis variants, making the method versatile across different robot types.
Solution Approach 2:
The calibration method transitions from a static disassembly-based approach to a dynamic measurement-based approach. The measurement device captures positions and orientations during actual robot operation, allowing calibration to adapt to different robot designs and configurations without requiring physical disassembly or modification of the robot structure.
3Measurement precision
If a jig is used to fix the longitudinal axes of drive arms to be parallel, then the drive arms are fixed at the same reference angle, but this does not address calibration of additional rotation and tilting axes in five-axis delta robots
Solution Approach 1:
The calibration method extends from the traditional two-dimensional plane calibration (fixing drive arms at reference angles) to three-dimensional spatial calibration by measuring positions and orientations in multiple dimensions. The measurement device captures spatial coordinates and orientation data that enable calibration of the additional rotation and tilting axes, adding a new dimension of calibration capability to five-axis and six-axis delta robots.
Data Source
AI summary
A method of calibrating a delta robot, the method including executing an arm movement by moving one driving link relative to other two driving links; measuring a movement of a point in fixed relationship with a tilting body during the arm movement as an arm measurement; executing a tilting movement by tilting the tilting body about a fifth axis; measuring a movement of the point during the tilting movement as a tilting measurement; and calibrating a fourth axis based on a comparison of the arm measurement and the tilting measurement. A method of calibrating the fifth axis, a control system, and a robot system are also provided.