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Lecture 10: Navigation
 

Lecture 10: Navigation

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    Lecture 10: Navigation Lecture 10: Navigation Presentation Transcript

    • Introduction to RoboticsNavigation
      April 5, 2010
    • Review: Localization
      Localization is probabilistic
      Error propagation law
      Markov localization and Kalman Filter
      Simultaneous Localization and Mapping
    • Last Exercise
      Beacon-based
      Line-based
      Maps are used for LOCALIZATION
    • Today: Navigation
      How to find a collision-free, shortest path from A to B?
      Two approaches:
      Local planning: go towards goal while avoiding obstacles
      Global planning: calculate shortest path offline
    • Global Planning
      Workspace
      Configuration Space
    • Graph-based and Potential-field Planning
      Grid-decomposition
      Visibility Graph
      Potential field
    • Configuration Space
      Grow obstacles at least by radius of robot
    • Voronoi Decomposition
    • Exact Cell Decomposition
    • Adaptive Cell Decomposition
    • Graph-based planning
      Dijkstra/
      Wavefront
      A*
    • Rapidly Exploring Random Trees
      Select a random point in the configuration space
      Grow tree into this direction from the closest point already in the graph
      Explores space quickly, and eventually completely
    • Potential-field based Planning
      Potential given by
      Distance to obstacles
      Direction to goal
      Possible to construct more complex behaviors
    • Calculate virtual force pulling at the robot
      Differential wheel robot
      Left wheel = Fx – Fy
      Right wheel = Fx + Fy
      Potential-Field based Planning
      x
      y
    • Reactive Obstacle Avoidance
      Goal
      Braitenberg behavior not sufficient (U-obstacle)
      Classic: bug-algorithms
      Easy to construct sub-optimal results
    • Vector Field Histogram
    • Practice
      Localization, actuation and obstacles are uncertain
      Combination of Local and Global Techniques
    • Debate Outline
      Constructive speeches
      10 minutes pro
      10 minutes contra
      Rebuttal
      3 minutes affirmative
      3 minutes negative
      Discussion and cross examination
      5-10 minutes
      4 Debates total
    • Debates
      Social:
      Robots putting humans out of work is a risk that needs to be mitigated.
      Robots should not have the capability to autonomously discharge weapons.
      Robotic cars should not be allowed to participate in urban traffic.

      Technical:
      Swarms of simple robots are more attractive than monolithic, more capable robots.
      Robots do not need to be as cognitive as humans in order to be useful as making the environment intelligent is sufficient.
      Robots need to be made differently than from links, joints, and gears in order to reach the agility of people.

      In both cases: debates should be driven by verifiable, technical arguments!
    • Debates
      Social:
      D1: Robots putting humans out of work is a risk that needs to be mitigated.
      D2: Robots should not have the capability to autonomously discharge weapons / drive around in cities (autonomous cars).
      Technical:
      D3: Robots do not need to be as cognitive as humans in order to be useful as making the environment intelligent is sufficient.
      D4: Robots need to be made differently than from links, joints, and gears in order to reach the agility of people.

      In both cases: debates should be driven by verifiable, technical arguments!
    • Random assignments
    • Organization
      Week 12 + 13: Debates
      http://courses.csail.mit.edu/6.141/spring2009/pub/debates/Debates.html
      Week 14: Graduate student presentations
      Week 15: Final presentations
      Final exam: Monday, May 3 7:30 p.m. - 10:00 p.m.