Cartesian coordinate robot: Difference between revisions

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[[Image:Descartes configuration.png|thumb|right|[[Kinematic diagram]] of Cartesian (coordinate) robot]]

[[File:Hp 9862a.jpg|thumb|A plotter is an implementation of the Cartesian coordinate robot.]]A '''Cartesian coordinate robot''' (also called '''linear robot''') is an [[industrial robot]] whose three [[principal axis (mechanics)|principal axes]] of control are linear (i.e. they move in a straight line rather than rotate) and are at [[right angle]]s to each other.<ref>{{Cite book|title=Mechatronics and Robotics Engineering for Advanced and Intelligent Manufacturing|lastlast1=Zhang|firstfirst1=Dan|last2=Wei|first2=Bin|date=2016|publisher=Springer|isbn=978-3-319-33580-3|___location=Cham|pages=31}}</ref> The three sliding joints correspond to moving the wrist up-down, in-out, back-forth. Among other advantages, this mechanical arrangement simplifies the [[Robot control]] [[arm solution]]. It has high reliability and precision when operating in three-dimensional space.<ref>{{Cite book|title=Advanced High Strength Steel And Press Hardening - Proceedings Of The 4th International Conference On Advanced High Strength Steel And Press Hardening (Ichsu2018)|lastlast1=Mingtu|firstfirst1=Ma|last2=Yisheng|first2=Zhang|date=2018|publisher=World Scientific|isbn=978-981-327-797-7|___location=Singapore|pages=526}}</ref> As a robot coordinate system, it is also effective for horizontal travel and for stacking bins.<ref>{{Cite book|title=Fundamentals of Robotics Engineering|last=Poole|first=Harry H.|date=2012|publisher=Van Nostrand Reinhold|isbn=978-94-011-7052-9|___location=New York|pages=35}}</ref>

== Configurations ==

[[File:Zaber motorized linear stage.jpg|thumb|Linear stage]]

[[File:Robot Portico tecno-840.jpg|thumb|Gantry robot]]

[[Robot]]s<ref>{{Cite book|last=Craig|first=John|title=Introduction to Robotics. Mechanics and Control|publisher=Addison-Wesley|year=1989|isbn=978-0-201-09528-9}}</ref><ref>{{Citation|last=Dagalakis|first=Nicholas G.|title=Industrial Robotics Standards|url=http://dx.doi.org/10.1002/9780470172506.ch24|work=Handbook of Industrial Robotics|year=1999|pages=447–459|place=Hoboken, NJ, USA|publisher=John Wiley & Sons, Inc.|doi=10.1002/9780470172506.ch24|isbn=978-0-470-17250-6|access-date=2020-12-28}}</ref> have [[Mechanism (engineering)|mechanisms]] consisting of rigid links connected together by [[Kinematic pair|joints]] with either linear (prismatic ''P'') or rotary (revolute ''R'') motion, or combinations of the two.  Active prismatic ''P'' and active revolute ''R'' joints are driven by motors under programmable control to manipulate objects to perform complex automated tasks. The linear motion of active prismatic ''P'' joints may be driven by rotary motors through gears or pulleys. Cartesian coordinate robots are controlled by mutually [[Perpendicular#:~:text=In elementary geometry, the property,intersect at a right angle.|perpendicular]] active prismatic ''P'' joints that are aligned with the ''X, Y, Z'' axes of a [[Cartesian coordinate system]].<ref>{{Cite journal|last=Descartes|first=Rene|date=2009-01-01|title=Discourse on the method of rightly conducting the reason, and seeking truth in the sciences|url=http://dx.doi.org/10.5214/ans.0972.7531.2009.160108|journal=Annals of Neurosciences|volume=16|issue=011|pages=17–21|doi=10.5214/ans.0972.7531.2009.160108|issn=0972-7531|hdl=2027/loc.ark:/13960/t20c64v5p|hdl-access=free}}</ref><ref>{{Cite journal|last=Klubertanz|first=George P.|date=1969|title=Discourse on Method, Optics, Geometry, and Meteorology. By Rene Descartes. Trans, with Introd. Paul J. Olscamp|url=http://dx.doi.org/10.5840/schoolman196946493|journal=The Modern Schoolman|volume=46|issue=4|pages=370–371|doi=10.5840/schoolman196946493|issn=0026-8402}}</ref>  Although not strictly `robots’, other types of [[Manipulator (device)|manipulators]], such as computer [[Numerical control|numerically controlled]] (CNC) machines, [[3D printing#Processes and printers|3D printers]] or [[Plotter|pen plotters]], also have the same  mechanical arrangement of mutually perpendicular active prismatic ''P'' joints.

'''Joint topology''' A single chain of links and joints connects a moving object to a base of [[serial manipulator]]s. Multiple chains (limbs) connect the moving object to the base of [[parallel manipulator]]s.<ref>Z. Pandilov, V. Dukovski, Comparison of the characteristics between serial and parallel robots, Acta Technica Corviniensis-Bulletin of Engineering, Volume 7, Issue 1, Pages 143-160</ref>  Most Cartesian coordinate robots are fully serial or a combination of serial and parallel connected linkages.  However, there are some Cartesian coordinate robots that are [[Cartesian parallel manipulators|fully parallel-connected]].<ref>{{Cite journal|lastlast1=Gosselin|firstfirst1=Clement M.|last2=Masouleh|first2=Mehdi Tale|last3=Duchaine|first3=Vincent|last4=Richard|first4=Pierre-Luc|last5=Foucault|first5=Simon|last6=Kong|first6=Xianwen|date=2007|title=Parallel Mechanisms of the Multipteron Family: Kinematic Architectures and Benchmarking|url=http://dx.doi.org/10.1109/robot.2007.363045|journal=Proceedings 2007 IEEE International Conference on Robotics and Automation|pages=555–560|publisher=IEEE|doi=10.1109/robot.2007.363045|isbn=978-1-4244-0602-19|s2cid=5755981}}</ref><ref>{{Cite journal|last=Gogu|first=Grigore|date=2004|title=Structural synthesis of fully-isotropic translational parallel robots via theory of linear transformations|url=http://dx.doi.org/10.1016/j.euromechsol.2004.08.006|journal=European Journal of Mechanics - A/Solids|volume=23|issue=6|pages=1021–1039|doi=10.1016/j.euromechsol.2004.08.006|bibcode=2004EJMS...23.1021G|issn=0997-7538}}</ref><ref>{{Cite journal|last=Wiktor|first=Peter|date=2020|title=Coupled Cartesian Manipulators|url=http://dx.doi.org/10.1016/j.mechmachtheory.2020.103903|journal=Mechanism and Machine Theory|volume=161|pages=103903|doi=10.1016/j.mechmachtheory.2020.103903|issn=0094-114X|doi-access=free}}</ref>

'''Degrees of freedom''' Since they are driven by linear active prismatic ''P'' joints, Cartesian coordinate robots typically manipulate objects with only linear translation ''T'' [[Degrees of freedom (mechanics)|degrees of freedom]].  However, some Cartesian coordinate robots also have [[Cartesian parallel manipulators|rotational ''R'' degrees of freedom]].<ref>{{Cite journal|last=Gogu|first=G.|date=January 2009|title=Structural synthesis of maximally regular T3R2-type parallel robots via theory of linear transformations and evolutionary morphology|url=http://dx.doi.org/10.1017/s0263574708004542|journal=Robotica|volume=27|issue=1|pages=79–101|doi=10.1017/s0263574708004542|s2cid=32809408|issn=0263-5747}}</ref>

'''Construction''' Each axis of a Cartesian coordinate robot typically is a [[linear stage]] consisting of a linear [[actuator]] geometrically parallel with [[Linear-motion bearing|linear bearings]]. The linear actuator is typically between two linear bearings spaced apart from each other to support [[Moment (physics)|moment]] loads.  Two perpendicular linear stages stacked on top of each other form an [[X-Y table|XY table]].  Examples of XY tables include the XY axes of [[Milling (machining)|milling machines]] or precision positioning stages.   At least one of the linear stages of [[cantilever]]ed Cartesian coordinate robots is supported at only one end. Cantilevered construction provides accessibility to parts for pick-and-place applications such as [[laboratory automation]] for example. Cartesian coordinate robots with the horizontal member supported at both ends are sometimes called gantry robots; mechanically, they resemble [[gantry crane]]s, although the latter are not generally robots. Gantry robots are often quite large and may support heavy loads.

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Popular applications for Cartesian coordinate robots are computer numerical control machine ([[CNC machine]]) and [[3D printing]]. The simplest application is used in milling machines and [[plotter]]s where a tool such as a router or pen translates across an ''X-Y'' plane and is raised and lowered onto a surface to create a precise design.

[[Automated storage and retrieval system|Pick and place]] machines are another application for Cartesian coordinate robots.  For example, overhead gantry Cartesian robots are [https://robot.cfp.co.ir/en/robots/cartesian-gantry applied] for continuous parts loading and unloading on [[CNC]] lathes production lines, performing 3-axis ''(X, Y, Z)'' pick and place operations of heavy loads with high speed performance and high positioning accuracy.  In general, overhead gantry Cartesian robots are suitable for many [[automation]] systems.<ref>{{cite web|title=When do you need a gantry robot|url=http://www.linearmotiontips.com/when-do-you-need-a-gantry-robot/|website=Linear Motion Tips|date=27 February 2015|publisher=Danielle Collins|access-date=21 September 2017}}</ref>

==See also ==