2006 Fiscal Year Final Research Report Summary
Fabrication of higher precision planer multi-joint positioning mechanism using high-performance joint elements and research on its limit of positioning accuracy
| Project/Area Number |
17560223
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Intelligent mechanics/Mechanical systems
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| Research Institution | SHINSHU UNIVERSITY |
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Principal Investigator |
FUKADA Shigeo Shinshu University, Faculty of Engineering, Professor, 工学部, 教授 (70156743)
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| Project Period (FY) |
2005 – 2006
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| Keywords | precision positioning / planer multi-joint mechanism / SCARA-type manipulator / joint mechanism / air bearing |
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| Research Abstract |
Though planer multi-joint positioning mechanism (SCARA-type manipulators) are in great demand on precision assembly lines, the positioning accuracy of current manipulators is much lower than Cartesian-type positioning mechanism. However, they have superior availability to assembly lines in factories because they have such a wide work range for such a small setting area. And they are expected to work as coordinate measuring machines in assembly lines. This study develops an novel planer multi-joint mechanism using high-performance joint elements, so as to realize an SCARA-type manipulator with 1 μm level positioning accuracy over working range of 300 × 200 mm. Moreover, it aims at researching the limits of positioning accuracy by the SCARA-type mechanism after strict calibration of link parameters.
The arm length of the developed mechanism is L_1=250 mm and L_2=147 mm. A high precision air bearing with accuracy of 0.05 μm is adopted to guide the joint axis, and a friction drive mechanism and a DC servomotor are devised to drive joint. And a rotary encoder with ultra-high resolution is devised that can detect the actual joint angle. The encoder resolution is 720×10^4 ppr for θ_1 and 144×10^4 ppr for θ_2. Moreover, the arm structure is arranged so that the center of gravity coincides with the joint axis.
The experiments are performed to control the joint angle with reference angle trajectory. It is confirmed that the joint angles are controlled to settle within the deviations of resolution angle. The dispersion range of the measured repeatability of 30 times positioning is within about ±3.5 μm (3σ), and it is verified that the area of dispersion ellipse is decreased to 10 % of conventional mechanism. The calibration of link parameters and more detailed evaluation of positioning accuracy are scheduled to perform on the next stage.
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Research Products
(6 results)
