Online Path Planning for Autonomous Underwater Vehicles in Unknown Environments Juan David Hernandez, Eduard Vidal, Guillem Vallicrosa, Enric Galceran, and Marc Carreras ICRA 2015 Presented by Youngki Kwon
Contents ● Introduction ● Main contribution ● Background ● Anytime path planning ● Lazy collision evaluation ● Octree-based map ● Main approach ● Framework ● Motion planning ● Experiment and result ● Summary 3
INTRODUCTION 4
Introduction ● AUVs must operate in unknown, cluttered and dynamic environments ● AUVs are more exposed to collisions ● Drift effects on the position estimated by navigation system ● Online capabilities of path planner make AUVs overcome global position inaccuracy 5
MAIN CONTRIBUTION 6
Main Contribution ● Combination of ideas from lazy collision evaluation and anytime path planning algorithm ● For online path planning ● incrementally built octree-based representation of the environment ● The experimental evaluation of the resulting planning framework using the SPARUS-II AUV in a real-world setting 7
BACKGROUND 8
Anytime Path Planning ● Overall approach ● Quickly find a solution that is feasible, but not necessarily optimal ● Exploit execution time to incrementally improve towards optimal solution ● Desired properties ● Form of completeness guarantees ● Asymptotic optimality given more computation time Anytime RRT* - Matthew Walter’s slide 9
Lazy Collision Evaluation ● Only check for collisions when we have to Check the collision after building the roadmap 11
Octree-based Map Techniques for 3d mapping - Wolfram burgard’s slide 12
Octree-based Map ● Octomap Techniques for 3d mapping - Wolfram burgard’s slide 13
MAIN APPROACH 14
Framework ● To solve start-to-goal queries for an AUV in an unknown environment ● Framework for path planning online for AUVs 15
Anytime Approach - Under the time constraint, current T is left image - Assume T is valid 𝒓 𝒉𝒑𝒃𝒎 Time limit 𝑺𝒑𝒑𝒖 16
Anytime Approach - Traverse T, check the collision, cut the subtree in collision 𝒓 𝒉𝒑𝒃𝒎 𝑺𝒑𝒑𝒖 Lazy Collision Evaluation 17
Anytime Approach - Sample configuration 𝒓 𝒉𝒑𝒃𝒎 𝑺𝒑𝒑𝒖 18
Anytime Approach - Extension in RRT* 𝒓 𝒉𝒑𝒃𝒎 𝑺𝒑𝒑𝒖 19
Anytime Approach - Extension in RRT* 𝒓 𝒉𝒑𝒃𝒎 𝑺𝒑𝒑𝒖 20
Anytime Approach - Extension in RRT* 𝒓 𝒉𝒑𝒃𝒎 𝑺𝒑𝒑𝒖 21
Anytime Approach - Extension in RRT* 𝒓 𝒉𝒑𝒃𝒎 𝑺𝒑𝒑𝒖 22
Anytime Approach - Extension in RRT* 𝒓 𝒉𝒑𝒃𝒎 𝑺𝒑𝒑𝒖 23
Anytime Approach - Find solution 𝒓 𝒉𝒑𝒃𝒎 𝑺𝒑𝒑𝒖 24
Anytime Approach - After Satisfying stop condition 𝒓 𝒉𝒑𝒃𝒎 𝑺𝒑𝒑𝒖 𝑺𝒑𝒑𝒖 25
EXPERIMENT & RESULT 26
Experiment & Result ● AUV use ● Pressure sensor, Doppler velocity log, IMU measurement, GPS ● Five Echosounders ● Experiments in both simulation and real world 27
Experiment & Result - Experiment in simulation 28
Experiment & Result - Experiment in real-world 29
SUMMARY 30
Summary ● Online capabilities of path planner make AUVs overcome global position inaccuracy ● Combination of ideas from lazy collision evaluation and anytime path planning algorithm 31
Q & A 32
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