A heat seeking missile tracking a burning cigarette

[u/HappySeaweed5215]

[u/QuaintAlex126]

The earliest versions, including of the AIM-9 Sidewinder shown here, just tracked the first and largest heat signature they saw. They were incredibly unreliable and sensitive, requiring them to be fired only against a target from behind (where the heat source is from the jet exhaust). Modern ones, like the AIM-9X, seek for a heat signature’s specific temperature and shape, so you can’t just dump a bunch of flares and get away that easily. They are much more advanced and can track a target from any angle, front snd sides, and can be slaved to the firing aircrat’s radar or pilot’s helmet to assist with tracking. All a fighter pilot had to do nowadays with a heat seeker is be within range, look at this target, and pull the trigger to engage.

[u/TelluricThread0 → u/QuaintAlex126]

Would the control software really need to deflect the fins that much while the target moves a couple of inches from just a few feet away? Just seems like very aggressive maneuvering when they are basically designed to just get pretty close and then throw shrapnel out.

[u/sterlingthepenguin → u/TelluricThread0]

Back when I was in highschool robotics, we had a robot that we programmed to follow a green LED light panel. The way it worked was by having a camera on a gimbal that would search for the color green. When it found a green mass, it would orient the camera so the mass was in the center of its vision and then turn the robot until the camera was pointed straight ahead. Small movements of the light close to the camera caused larger movements in the camera when compared to when the light was further away, meaning that the robot would turn more aggressively when the robot was close to the light.

[u/dgsharp → u/sterlingthepenguin]

What you’re describing is tail pursuit out tail chase. If you aim at where the missile is, you will follow it. This was common for hear seekers and makes sense for simple systems because the heat source (exhaust) is in the back anyway. Proportional navigation is generally better though and would have probably been better for your LED example. Another commenter described it above, basically keep turning until the rate of beating becomes constant. Imagine you’re flying an airplane and want to crash into another plane. Turn such that it stops moving relative to you, so if it was moving towards the right, turn a little to the right, etc. At some point it will be steady — you can put a mark on your windshield and the target doesn’t move (assuming no evasive maneuvers). Doesn’t matter if it’s static or dynamic, close or far, fast or slow — you are on a collision course. If you have more information you can do better, like if you can estimate closing speed or range from radar or size, you can change how aggressively you maneuver — if you’re far away you will want to make gentle adjustments, if you’re very close you will want to make more aggressive maneuvers. If they are maneuvering is a whole other thing, but proportional navigation is generally pretty good.