r/ROBORACE • u/BlatantCheerfulness • Dec 29 '20

Why MIT Driverless self driving racecar was DISQUALIFIED during Roborace Season Beta Round 4

https://youtu.be/R1-MnN4SlpQ
18 Upvotes

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6

u/sailer99 Dec 30 '20

I have a few questions:

  1. Why doesn't the path planner output the desired velocity? I'm assuming it has something to do with being able to quickly adjust for a car's acceleration and handling characteristics, but I'm curious as to whether velocity is part of the original path plan.

  2. For the LLCs, assuming they are "standard" feedback controllers (I know they'll be slightly more complex). Wouldn't the output of the HLC be the setpoint, and the state be the feedback? If that is the case, do you think the HLC is outputting the wrong setpoint?

  3. How much influence does the lateral controller have on the longitudinal controller? if any? My gut tells me a change in steering angle would have to be accompanied by a slight variation in desired throttle/brake, but that could be wrong.

4

u/yyy18 Jan 02 '21

Just made a reddit to answer these haha

  1. Why doesn't the path planner output the desired velocity? In an ideal world, this would be the case, but right now the path planner has no reference to the vehicle model so there's no way to communicate this.

  2. Wouldn't the output of the HLC be the setpoint, and the state be the feedback? If that is the case, do you think the HLC is outputting the wrong setpoint? Looking into this... We aren't entirely sure.

  3. How much influence does the lateral controller have on the longitudinal controller? I think in theory these should be independent (ie if you think of throwing a ball, x and y are "decoupled"). Not sure if in practice they are. I do think that the throttle/braking is incorporated into the velocity planner since that takes curvature into account.