Monday, April 13, 2009

Simulation of a pure pursuit problem - An example

  • A fighter aircraft sights an enemy bomber and flies directly towards it in order to catch up bomber and destroy it.
  • Pure Pursuit - The simple strategy of pursuer redirecting himself toward the target at fixed intervals of time, while the target goes on its predetermined path without making any effort to evade the pursuer.
  • If path of the target is straight then problem can be solved directly using analytical techniques.
  • However, if path of the target is curved then problem becomes more complex and cannot be solved directly but through simulation only.
  • Conditions to simulate must be well specified first.
  • Some formulae used here:
Dist(t) = sqrt((yb(t)-yf(t))exp2+(xb(t)-xf(t))exp2)

Sin (theta) = yb(t)-yf(t) / dist(t)
Cos(theta) = xb(t) - yf(t) / dist (t)

Given position at time 't', next position at time 't+1' is computed using:

Xf(t+1) = xf(t) + vf*cos(theta)
Yf(t+1) = yf(t) + vf*sin(theta)

  • Analytically we cannot make a long term prediction about the path that the fighter plane would take (given the initial position and path of the target). But by Simulation, we were able to make instant-to-instant predictions for as many instants as we wanted.

1 comment:

vinodh said...

hellow sir,

can i get a code for this pure pursuit algorithm in C language..

i am unable to do so...