free shape paths in industrial robots
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DESCRIPTION
Approach to implement free shape paths in generic industrial robots. Bezier curve descriptors can be storage as standard points. Feasible to implement the Decasteljau algorithm within robot controllers. Current and future industrial robotic applications might need free shape path capabilities to cooperate with humans and other machines.TRANSCRIPT
Free Shape Paths in Industrial Robots
•Date: Octoer, 2012•Linked to: AESOP
Contact information
Tampere University of Technology,
FAST Laboratory,
P.O. Box 600,
FIN-33101 Tampere,
Finland
Email: [email protected]
www.tut.fi/fast
Conference: 38th Annual Conference of the IEEE Industrial Electronics Society
Title of the paper: Free Shape Paths in Industrial Robots
Authors: Luis E. Gonzalez Moctezuma, Andrei Lobov, Jose L. Martinez Lastra
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Free Shape Paths in Industrial Robots
Authors: Luis E. Gonzalez Moctezuma, Andrei Lobov, Jose L. Martinez Lastra
Tampere University of TechnologyFactory Automation Systems and Technology Lab
IECON 2012, Montreal, Canada25-28.10.2012
Outline
• Motivation
• Bezier curves
• Curve approximation: arc and linear segments
• Comparison
• Implementation
• Conclusions
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Motivation (1/2)• 2008: 1.3 million of industrial robots
• Simple movements in industrial robots– Linear– Circular
• Need for free shape paths in robotic applications:– Welding– Fluid dispensing– Painting processes– Interaction and cooperation with humans
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Motivation (2/2)
• How to enable standard industrial robots to perform free shape paths?
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Bezier curves (1/2)• Introduced by Pierre Bezier – Renault
• Curves described by a parametric function
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Bezier curves (2/2)
• Control, flexibility, intuitive
• Use and tools in:– Industrial design– CAD– 3D modelling– Vector-based drawing
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Approximation by arc segments
• Implementation of algorithm proposed by: Riskus, Aleksas. “Approximation of a Cubic Bezier Curve by Circular Arcs and Viceversa”
– Find inflection points (curvature change in sign)– Segments subdivided to reach biarcs <90°
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Approximation by linear segments• 1) Evaluate directly on the polynomial
function: Numerically unstable
• 2) Use the De Casteljau algorithm– Uses parameter t – and Bezier descriptors
Numerically stable
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Comparison: arc Vs linear segments
*
*Interpolations can be computed in the target (industrial robot controller)
Implementation• SCARA robot (~15 years old)
• De Casteljau algorithm within the robot controller
• Transfer to controller just Bezier descriptors
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Conclusions
• Approach to implement free shape paths in generic industrial robots.
• Bezier curve descriptors can be storage as standard points
• Feasible to implement the Decasteljau algorithm within robot controllers
• Current and future industrial robotic applications might need free shape path capabilities to cooperate with humans and other machines
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Questions?
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