2. Last Lecture Robots Sense Compute Actuate Communicate If they don’t they are just automatons (but the boundary is vague)
3. Last week’s exercise Intro to Webots How to create a wall What you see / what the robot sees Sensors: distance & camera Physics
4. What is locomotion? Latin: moving from place to place Crawling Sliding Running Jumping Walking Rolling
5. Other forms of locomotion Swimming Gliding Flying Propulsion
6. Locomotion relationships Swimming to walking Walking to rolling Gliding to flying Running to jumping A.J. Ijspeert, A. Crespi, D. Ryczko, and J.M. Cabelguen. From swimming to walking with a salamander robot driven by a spinal cord model. Science, 9 March 2007, Vol. 315. no. 5817, pp. 1416 - 1420, 2007.
7. Nature vs. Technology Robots become more and more capable of imitating natural locomotion schemes Nature did not evolve rotating shafts / rotational joints Hinge joint Ball and socket joint
8. Walking vs. rolling If the terrain allows, rolling is more efficient Walking requires more Structural complexity Joints Control
9. Characterization of locomotion Stability Number of contact points Center of gravity Static/Dynamic Stabilization Inclination of terrain Contact Point vs. Area Friction vs. grasp 3-Point rule 3 legs : static stability 6 legs : static walking
13. Industry 2-legged locomotion popular because suited to human environment hardest to control Commercial prototypes 4-legged locomotion Not statically stable Commercial prototypes 6-legged locomotion Statically stable Forestry http://www.youtube.com/watch?v=FAcgSi6pzv4 http://www.youtube.com/watch?v=CD2V8GFqk_Y
14. Wheeled locomotion Most appropriate for most applications Stable with at least 3 wheels Steered wheels make control more complex pretty quickly Stable zone
15. Wheel suspension Suspension consists of a spring and damper The damper absorbs shock The spring counteracts the shock Result: wheel remains on ground Better traction Better control
16. Omni-Directional Drive Swedish Wheel Rotation around wheel axle Rotation around the rollers Rotation around contact point Uranus, CMU
18. Dynamic Stability The system has to move in order not to fall over Active balance Inertia is used to overcome unstable states Examples are Running Getting up Inverted Pendulum
19. Design Lets design robots that Crawl Slide Gallop Jump Walk Roll Crawling Sliding Running Jumping Walking Rolling
20.
21. Crawling Mechanics of Soft Materials Laboratory http://ase.tufts.edu/msml/researchInchBot.asp
22. Sliding Gavin Miller Hirose-Fukushima lab http://www-robot.mes.titech.ac.jp/robot_e.html
26. Homework Chapter 3 Required for exercise in Week 4 Read till September 13 No class next week! Hints read the questions first Skip: 3.2.3.4-5 Skim: 3.2.4-3.3.3 Understand what Maneuverability (Mobility and Steerability is) conceptionally Goal: determine the speed of your robot’s motors so that it can follow a desired trajectory
27. Next exercise Locomotion (Wednesday) Play with different locomotion concepts in Webots Understand various gaits and implement your own
