RockSample.jl

Implement the rock sample problem using POMDPs.jl
Author JuliaPOMDP
Popularity
1 Star
Updated Last
2 Years Ago
Started In
April 2019

RockSample.jl

Build Status Coverage Status codecov

Implement the RockSample [1] problem with the POMDPs.jl interface.

[1] T. Smith, R. Simmons, "Heuristic Search Value Iteration for POMDPs," in Association for Uncertainty in Artificial Intelligence (UAI), 2004

Rock Sample Illustration

Installation

using Pkg
Pkg.add(PackageSpec(url="https://github.com/JuliaPOMDP/RockSample.jl"))

Problem description

  • States: position of the robot and status of the rocks.

  • Actions: There are 5 basic actions, moving up, down, left, and right, and sampling a rock and $K$ sensing actions to check the state of a rock. When sampling or sensing, the robot does not move.

  • Transition model: When taking a moving action, the robot moves deterministically to the desired cell. The robot can only exit the map by the exit area (on the right side of the grid). Actions that causes the robot to go over the edge of the grid have no effects.

  • Observation model: The robot can observe the status of the rock with some noise when executing a sensing action. The noise varies exponentially with the distance to the rock. The decaying rate is controlled by the parameter sensor_efficiency. If the robot is moving or sampling it does not receive an observation (receives :none).

  • Reward model: The robot receives a positive reward of exit_reward for reaching the exit area. When sampling, the robot receives a reward of good_rock_reward if the sampled rock is good or bad_rock_penalty (negative number) if the rock is bad.

Example

using POMDPs
using RockSample 
using SARSOP # load a  POMDP Solver
using POMDPGifs # to make gifs

pomdp = RockSamplePOMDP(rocks_positions=[(2,3), (4,4), (4,2)], 
                        sensor_efficiency=20.0,
                        discount_factor=0.95, 
                        good_rock_reward = 20.0)

solver = SARSOPSolver(precision=1e-3)

policy = solve(solver, pomdp)

sim = GifSimulator(filename="test.gif", max_steps=30)
simulate(sim, pomdp, policy)

RockSamplePOMDP Parameters:

  • constructor: RockSamplePOMDP{K}(kwargs...) where K is an integer representing the number of rocks
  • keyword arguments:
    • map_size the size of the grid, default (5,5)
    • rocks_positions::Vector{RSPos} , the list of positions of the rocks
    • init_pos::RSPos the initial position of the robot, default (1, 1)
    • sensor_efficiency::Float64, the decaying rate of the sensor performance, default 10.0
    • bad_rock_penalty default -10
    • good_rock_reward default 10
    • exit_reward default 10
    • discount_factor default 0.95

Internal types:

RSPos : represent a position in the grid as a static array of 2 integers. RSState: represent the state of the POMDP. The field pos::RSPos is the position of the robots and the field rocks::SVector{K, Bool} represents the status of the rocks (good or bad).

Used By Packages

No packages found.