void natural ()
 {
  if (affordance<0) precision(); //default
  if (grasps[affordance].equals("PRECISION")) precision();
  else
  if (grasps[affordance].equals("SIDE")) side();
  else
  if (grasps[affordance].equals("POWER")) power();
  else
  if (grasps[affordance].equals("POWER2")) power2();
  else 
  if (grasps[affordance].equals("REACHONLY")) reachonly();
else
    if (grasps[affordance].equals("REACHOFFSET")) reachoffset();
  else  {System.err.println("internal error: No such grasp!"); return;}
 }