Ball and Beam Predictive

First try controlling it by hand, then try auto.
Interval between camera steps = seconds
You can change the angle or target, target = 0

<![CDATA[
function loop(){
  ctx.lineWidth=3;
  drawit('white'); //erase previous
//step: discrete time
  if(twaiting<0){
    predict();
    if(manual){drive=Math.sign(stepdem-steps);}    
    twaiting=interval;
    steps+=drive;
    steps=limit(steps,50);  
  }
  twaiting-= dt;
//dynamics
  cos=Math.cos(steps*radperstep);
  sin=Math.sin(steps*radperstep);
  v= v+4*sin*dt;  
//apply end-stop
  if((Math.abs(x)>1)&&(x*v>0)){v=0;}
  x= x+v*dt;                  //This is the simulation
  t= t+dt;
//control
//  predict();

ctx.lineWidth=1;
  drawit("black");

if(t<tmax){setTimeout("loop();", 10);}
}

function predict(){
  var ufp = 1;
  var ufn = -1;
  
  //reset both models
  tw=twaiting;
  afp=steps; vfp=v; xfp=x;
  afn=steps; vfn=v; xfn=x;
  tf=0;
 
  do{
    if(tw<0){
      tw=interval;
      afp+=ufp;
      afp=limit(afp,50);  
      afn+=ufn;
      afn=limit(afn,50);  
    }
    tw-= dt;
//step positive model
    vfp = vfp + 4*radperstep * afp * dtf;
    xfp = xfp + vfp * dtf;
    Colour("green");
    Spot((t+tf)/30-1, xfp/10-0.13);

//step negative model
    vfn = vfn + 4*radperstep * afn * dtf;
    xfn = xfn + vfn * dtf;
    Colour("red");
    Spot((t+tf)/30-1, xfn/10-0.13);

tf+=dtf;

offp=(afp<0)|(vfp<0)|(xfp<xtarget); //positive offside?
    offn=(afn>0)|(vfn>0)|(xfn>xtarget);	//negative offside?

} while(offp&&offn); //loop while both are offside
        
  if(offp){drive=1;}else if(offn){drive=-1;} else {drive=0;} 
//if one of them is still offside, that is the value for u

Colour("black");
    Spot(t/30-1, steps/500-0.13);

//  dt=tf/ratio +.004; //plant step increases with time to decision
}

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