[HN Gopher] A Real-Time Algorithm for Non-Convex Powered Descent...
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       A Real-Time Algorithm for Non-Convex Powered Descent Guidance [pdf]
        
       Author : nill0
       Score  : 40 points
       Date   : 2025-04-19 12:25 UTC (3 days ago)
        
 (HTM) web link (depts.washington.edu)
 (TXT) w3m dump (depts.washington.edu)
        
       | RansomStark wrote:
       | I must be half asleep, I was expecting some novel machine
       | learning algorithm. I was pleasantly surprised to find a
       | spaceflight algorthim instead.
       | 
       | I am completely out of my depth, so have nothing constructive to
       | add. But it sounds interesting.
        
         | wiz21c wrote:
         | Funny, I fell into that one too... I guess "guidance" has a few
         | letters in common with "gradient" so our brain triggers...
         | 
         | See: https://medium.com/@stephenwatathi/the-brains-power-to-
         | read-...
        
       | vessenes wrote:
       | This is the algorithm SpaceX uses to catch rockets. If you watch
       | any of the landings/chopstick catches, you'll notice that they
       | don't seem to oscillate back and forth like a lot of control
       | systems we're "used to" seeing.
       | 
       | This algorithm is why! Super cool.
        
         | metalman wrote:
         | so as soon as the rocket starts to fall @ the minimum controll
         | speed, they draw a virtual strait line between the rocket and
         | the landing spot, and follow it, sort of an inverse geodetic
         | line, compensate for wind with the "flaps" and vectored thrust
         | on the rockets, giving enough horizontal thrust, and gravity
         | providing a very steady and reliable pull makes a lot of sense,
         | as it is the most fuel efficient and fastest return, and any
         | issues with guidance are imediately clear, making it part of
         | the abort system as well
        
       | xiaoyu2006 wrote:
       | Reminds me of L. Blackmore's
       | https://www.semanticscholar.org/paper/Lossless-Convexificati...
        
       | pugworthy wrote:
       | Would love to see this control a classic Lunar Lander type game
       | such as http://moonlander.seb.ly/
        
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       (page generated 2025-04-22 23:01 UTC)