View source for Klann linkage

{{Short description|Planar mechanism designed to simulate the gait of legged animals}}
{{refimprove|date=November 2016}}
[[File:Klann linkage, lobsterbot.jpg|thumb|Underwater walking robot, using Klann leg linkages in laser-cut and anodised aluminium.<ref>{{Citation
  |url=http://eprints.uwe.ac.uk/16101/1/Clawar_TomR_Vs1.0%20%281%29.pdf
  |author=Rooney, T. |author2=Pearson, M. |author3=Welsby, J. |author4=Horsfield, I. |author5=Sewell, R. |author6=Dogramadzi, S. 
  |title=Artificial active whiskers for guiding underwater autonomous walking robots
  |series=CLAWAR 2011
  |date=6–8 September 2011
  |location=Paris, France
}}</ref>]]
The  '''Klann''' '''linkage''' is a [[Plane (geometry)|planar]] mechanism designed to simulate the gait of legged animal and function as a wheel replacement, a [[leg mechanism]]. The [[Linkage (mechanical)|linkage]] consists of the frame, a [[Crank (mechanism)|crank]], two grounded [[rocker arm|rockers]], and two couplers all connected by [[pivot joints]].  It was developed by Joe Klann in 1994 as an expansion of [[Burmester's theory|Burmester curves]] which are used to develop four-bar double-rocker linkages such as harbor [[Crane (machine)|crane booms]].<ref>{{cite web|url=http://www.mechanicalspider.com/enable.html|archive-url=https://web.archive.org/web/20040414054817/http://mechanicalspider.com/enable.html|archive-date=14 April 2004|title=Mechanical Spider|work=Klann Research And Development, LLC|access-date=22 November 2016}}</ref> It is categorized as a modified Stephenson type III [[kinematic chain]].<ref>U.S. Provisional Application Ser. No. 60/074,425, was filed on Feb. 11, 1998</ref><ref name=patent6260862>{{US patent|6260862}}</ref><ref>{{US patent|6364040}}</ref><ref>{{US patent|6478314}}</ref>

The proportions of each of the links in the mechanism are defined to optimize the linearity of the foot for one-half of the rotation of the [[Crank (mechanism)|crank]]. The remaining rotation of the crank allows the foot to be raised to a predetermined height before returning to the starting position and repeating the cycle. Two of these linkages coupled together at the crank and one-half cycle out of phase with each other will allow the frame of a vehicle to travel parallel to the ground.

The Klann linkage is supposed to provide many of the benefits of more advanced walking vehicles without some of their limitations. It can step over curbs, climb stairs, or travel into areas that are currently not accessible with wheels but does not require microprocessor control or multitudes of actuator mechanisms. It fits into the technological space between these walking devices and axle-driven wheels.

== Mechanism ==
Klann linkage work on the basis of [[kinematics]] where all links gives relative motion with each other. It converts the rotatory motion to linear motion, and looks like an animal walking.<ref>{{cite magazine|url=https://www.wired.com/2010/02/robotic-spider-melds-legos-and-3-d-printing/|title=Robotic Spider Melds Legos and 3-D Printing|first=Priya|last=Ganapati|magazine=[[Wired (magazine)|Wired]]|access-date=22 November 2016}}</ref> 

[[Image:F1-positions.gif|thumb|center|575px|These figures show a single linkage in the fully extended, mid-stride, retracted, and lifted positions of the walking cycle. These four figures show the crank (rightmost link in the first figure on the left with the extended pin) in the 0, 90, 180, and 270 degree positions.]]This animation shows the working of a klann mechanism. [[Image:F4-motion.gif|thumb|center|575px|This is a repeating animation of the legs in motion with the near legs of each set outlined in blue. A reasonable understanding of the functioning of the linkage can be gained by focusing on a specific point and following it through several cycles. Each of the pivot points is displayed in green. The three positions grounded to the frame for each leg are stationary. The upper and lower rockers move back and forth along a fixed arc and the crank traces out a circle.]]

[[File:Klann-MovementPaths-PatentDrawingBelow.svg|thumb|center|575px|Movement paths of each point (in blue is the ground link)]]
{{clear}}

== Comparison with Jansen's linkage ==
{{unreferenced|section|date=November 2016}}
[[File:Strandbeest-Walking-Animation.gif|thumb|Jansen Linkage ]]
The Klann mechanism uses six links per leg, whereas the [[Jansen's linkage]] developed by [[Theo Jansen]] uses eight links per leg, with one [[degree of freedom]].

== Example leg ==
[[File:Klann-Table1.svg|thumb|example leg illustrated]]
In {{US Patent|6,260,862}} there is a set of coordinates for an example leg:<ref name=patent6260862/>
{|class="wikitable"
! Point !!     X !! Y !! Description
|-
!colspan="4"| Fixpoints 
|-
|   9   || 1.366 || 1.366 || first rocker arm axle
|-
|  11   || 1.009 || 0.574 || second rocker arm axle
|-
|  15   || 1.599 || 0.750 || crank shaft
|-
!colspan="4"| fully extended ground stride position
|-
| 27X   || 0.741 || 0.750 || elbow joint
|-
| 29x   || 1.331 || 0.750 || crank
|-
| 33x   || 0.000 || 0.000 || foot
|-
| 35x   || 0.232 || 0.866 || knee joint/axle
|-
| 37x   || 0.866 || 1.500 || hip joint
|-
!colspan="4"| grounded gait position 
|-
| 27Y   || 1.277 || 0.750 ||  elbow joint
|-
| 29y   || 1.867 || 0.750 ||  crank
|-
| 33y   || 1.000 || 0.000 ||  foot
|-
| 35y   || 0.768 || 0.866 || knee joint/axle
|-
| 37y   || 1.000 || 1.732 ||  hip joint
|}

==See also==
*[[Wheel]]
*[[Linkage (mechanical)]]
*[[Leg mechanism]]
*[[Mondo Spider]]
*[[Jansen's linkage]]
*[[Chebyshev linkage]] and [[Chebyshev's Lambda Mechanism]]

==References==
{{reflist}}

==External links==
{{Commons category|Klann linkages}}
{{wikibooks|Klann linkage}}
*{{youtube|QwJ5c902jCc|Klann Linkage In Phun }} Animation of the linkage's climbing ability
*{{youtube|iKCb7u_ZVcQ|Legs, mk2}} Clear side-on view of linkage in motion
*{{youtube|skwF7IdNPIw|Son of Mr Crabby - CamBam made Klann linkage walking crab robot }}
*[https://web.archive.org/web/20040324035309/http://mechanicalspider.com/ Mechanicalspider]
*[http://www.mekanizmalar.com/mechanicalspider.shtml Mechanisms101] {{Webarchive|url=https://web.archive.org/web/20090202122559/http://www.mekanizmalar.com/mechanicalspider.shtml |date=2009-02-02 }}
*[http://www.mondospider.com Mondo Spider]
*[https://web.archive.org/web/20060406073850/http://www.moltensteelman.mechanicalspider.com/ Walking Beast]
*[http://www.crabfu.com/steamtoys/rc_steam_spider Crabfu] {{Webarchive|url=https://web.archive.org/web/20110807173043/http://www.crabfu.com/steamtoys/rc_steam_spider/ |date=2011-08-07 }}

{{Mobile robots}}

[[Category:Linkages (mechanical)]]
[[Category:Walking vehicles]]
[[Category:Robot kinematics]]
[[Category:1994 in robotics]]