Localization in practice (Thu Oct 17, lect 14) | previous | next | slides |

Look at the mechanics of SLAM and AMCL

Reminder: Readings are your responsibility. You will be expected to come to class prepared, having read the material, and ready to participate in the discussion ## Logistics

  • Overall impressions of wall follower submisions
  • Many algorithms looked similar. This is likely because of google, chatgpt, or student cooperation
  • And if that’s as far as it went, that’s perfect
  • You found that algorithms that work in sim dont work as is in real life. This is a well known fact.
  • The sim is never going to reproduce the quirks of a TB3
  • Try to modularize more
  • Write functions, methods, classes or nodes to represent separable algorithms
  • Especially Nodes
  • Lets slook at the Lidar Scan Message a little closer.

Localization

AMCL Particles Display

Monte Carlo

  • AMCL: Advanced Monte Carlo Localization** (I’ve also seen “Augmented” and “Adaptive”. Go figure.)
  • Why Monte Carlo? That’s where the Casinos are!
  • Algorithms that incorporate random guesses when a direct solution is hard or not feasible
  • Diagram on the board how you would calculate Pi using a Monte Carlo Algorithm
  • Note for PI it’s a very inefficient way to get an accurate result
  • But it illustrates the idea of Monte Carlo estimation

Particle Filter

  • Lets watch a short Video About Particle FIlters
  • Markov localization means that the new state is dependent only on the previous state (and not the history) and that the probability distributions are
  • Markov localization = state estimation from sensor data
  • Instead of “solving” the equation for all data and all points
  • Use a Monte-Carlo technique
  • Generate a random collection of candidate locations
  • Compute the motion
  • Adjust the probability of each particle

Further references

Thank you. Questions?  (random Image from picsum.photos)