Difference between revisions of "Euler's spiral (Clothoid)"

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Line 9: Line 9:
  
 
<jsxgraph width="500" height="500" box="box2">
 
<jsxgraph width="500" height="500" box="box2">
  var b2 = JXG.JSXGraph.initBoard('box2', {originX: 250, originY: 250, unitX: 25, unitY: 25});
+
  var b2 = JXG.JSXGraph.initBoard('box2', {boundingbox: [-10, 10, 10, -10]});
 
  var k1 = b2.create('slider', [[1,8],[5,8],[0,2,8]],{name:'k'});
 
  var k1 = b2.create('slider', [[1,8],[5,8],[0,2,8]],{name:'k'});
 
  var len = b2.create('slider', [[1,7],[5,7],[1,2,3.2]],{name:'len'});
 
  var len = b2.create('slider', [[1,7],[5,7],[1,2,3.2]],{name:'len'});
Line 23: Line 23:
 
===The JavaScript code to produce this picture===
 
===The JavaScript code to produce this picture===
  
<source lang="xml">
+
<source lang="javascript">
<jsxgraph width="500" height="500" box="box2">
+
  var b2 = JXG.JSXGraph.initBoard('box2', {boundingbox: [-10, 10, 10, -10]});
  var b2 = JXG.JSXGraph.initBoard('box2', {originX: 250, originY: 250, unitX: 25, unitY: 25});
 
 
  var k1 = b2.create('slider', [[1,8],[5,8],[0,2,8]],{name:'k'});
 
  var k1 = b2.create('slider', [[1,8],[5,8],[0,2,8]],{name:'k'});
 
  var len = b2.create('slider', [[1,7],[5,7],[1,2,3.2]],{name:'len'});
 
  var len = b2.create('slider', [[1,7],[5,7],[1,2,3.2]],{name:'len'});
Line 35: Line 34:
 
  var p = b2.create('glider',[c],{name:''});
 
  var p = b2.create('glider',[c],{name:''});
 
  var t = b2.create('tangent',[p],{dash:3,strokeWidth:1,strokeColor:'red'});
 
  var t = b2.create('tangent',[p],{dash:3,strokeWidth:1,strokeColor:'red'});
</jsxgraph>
 
 
</source>
 
</source>
  

Revision as of 16:07, 7 June 2011

Euler's spiral is defined as a curve whose curvature changes linearly with its curve length. Other names for the spiral are clothoid and spiral of Cornu or Cornu spiral.

Euler spirals are widely used as transition curve in rail track / highway engineering for connecting and transiting the geometry between a tangent and a circular curve.

The curve can be described in parametric form by

[math] x = k\cdot\int_0^t \sin(\frac{u^2}{2}) du\; [/math]
[math] y = k\cdot\int_0^t \cos(\frac{u^2}{2}) du\; [/math]

The JavaScript code to produce this picture

 var b2 = JXG.JSXGraph.initBoard('box2', {boundingbox: [-10, 10, 10, -10]});
 var k1 = b2.create('slider', [[1,8],[5,8],[0,2,8]],{name:'k'});
 var len = b2.create('slider', [[1,7],[5,7],[1,2,3.2]],{name:'len'});
 var c = b2.create('curve', 
             [function(t){ return k1.Value()*b2.I([0,t],function(u){return Math.sin(u*u*0.5);}); }, 
              function(t){ return k1.Value()*b2.I([0,t],function(u){return Math.cos(u*u*0.5);}); },
              function(){return -len.Value()*Math.PI;}, function(){return len.Value()*Math.PI;}],
             {strokewidth:1});      
 var p = b2.create('glider',[c],{name:''});
 var t = b2.create('tangent',[p],{dash:3,strokeWidth:1,strokeColor:'red'});

External links