Lesson 3: Particle Filter - RobotWorld

Lesson 3: Particle Filter - RobotWorld

Classes, Instance, and Inheritance (WebChurch)

;------------------------------------------------------------------------------------------------------

;   - WebChurch code by PCM 2016/03/27 -
;
;   Landmarks and World Size of Particle World
;   (Thrun, AI for Robotics)
;   www.udacity.com/course/viewer#!/c-cs373/l-48704330/m-48683730
;   ....................
;------------------------------------------------------------------------------------------------------

The world for localization by particle filtering is a simple 2-D square with edge length 100. It contains four landmarks to support the position finding process. From the programming language perspective the main problem is that Thrun used an object-oriented approach in Python. This implies mutation of local states of instance objects. Because WebChurch is purely functional we cannot use mutations. So we have to look for an object-based style with a functional state. So we take the old state as an input-argument and the new state as a functional output so that the methods remain pure functions.

(define landmarks '((20.0 20)(80.0 80.0)(20.0 80.0)(80.0 20.0))) (define world_size 100)

Class Functions (e.g. Move) with Nested Defines and Command Sequences as Function Compositions (WebChurch)

((my-robot move) '(10 10 0) 0 10) = (20 10 0) (send my-robot move '(10 10 0) 0 10) = (20 10 0)
((my-robot move) '(10 10 0) (/ pi 2) 10) = (10.000000000448965 20 1.57079632675) (send my-robot move '(10 10 0) (/ pi 2) 10) = (10.000000000448965 20 1.57079632675)
(send my-robot move (send my-robot move (send my-robot move (send my-robot set-state '(10 10 0)) 0 10) (/ pi 2) 10) (- 0 (/ pi 2)) 0) = (20.000000000448967 20 0)

Move and Sense with Nested Defines (WebChurch)

(send my-robot sense (send my-robot move (send my-robot set-state '(10 10 0)) (/ pi 2) 10))
(display (send my-robot sense (send my-robot move (send my-robot sense (send my-robot move (send my-robot sense (send my-robot move (send my-robot set-state (list 30 50 (/ pi 2))) (- 0 (/ pi 2)) 15))(- 0 (/ pi 2)) 10)) (- 0 (/ pi 2)) 0)))

Move and Sense with Nested Lambdas (WebChurch)

;------------------------------------------------------------------------------------------------------
; - WebChurch code by PCM 2016/04/08 -
; instruction is taken from S.Thrun's lecture "AI for Robotics"
;  "Make a robot called myrobot that starts at coordinates 30, 50 heading north (pi/2).
;   Have your robot turn clockwise by pi/2, move 15 m, and sense.
;   Then have it turn clockwise by pi/2 again, move 10 m, and sense again.
;   Your program should print out the result of your two sense measurements."
;   (S.Thrun, AI for Robotics)
;   www.udacity.com/course/viewer#!/c-cs373/l-48704330/e-48480592/m-48699551
;------------------------------------------------------------------------------------------------------

(display (send my-robot sense (send my-robot move (send my-robot sense (send my-robot move (send my-robot sense (send my-robot move (send my-robot set-state (list 30 50 (/ pi 2))) (- 0 (/ pi 2)) 15))(- 0 (/ pi 2)) 10)) (- 0 (/ pi 2)) 0)))

A Markov Model for Actions, States, and Observations (WebChurch)

A Markov Model for Actions, States, and Observations in a Cyclic World (WebChurch)

S. Thrun, AI for Robotics, Lesson 3, Particle Filters, Cyclic World, https://www.udacity.com/course/viewer#!/c-cs373/l-48704330/m-48700464
(Changed: 19 Jan 2024)  | 
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