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Robotic Locomotion Howie Choset 16-311

Robotic Locomotion Howie Choset 16-311. Design Tradeoffs with Mobility Configurations. Maneuverability Controllability Traction Climbing ability Stability Efficiency Maintenance Environmental impact Navigational considerations Cost Simplicity in implementation and deployment

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Robotic Locomotion Howie Choset 16-311

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  1. Robotic LocomotionHowie Choset16-311

  2. Design Tradeoffs with Mobility Configurations • Maneuverability • Controllability • Traction • Climbing ability • Stability • Efficiency • Maintenance • Environmental impact • Navigational considerations • Cost • Simplicity in implementation and deployment • Versatility • Robustness

  3. Differential Drive Pictures from “Navigating Mobile Robots: Systems and Techniques” Borenstein, J. Where D represents the arc length of the center of the robot from start to finish of the movement.

  4. Differential Drive (continued) Advantages: • Cheap to build • Easy to implement • Simple design • Disadvantages: • Difficult straight line motion Photo courtesy of Nolan Hergert

  5. Problem with Differential Drive: Knobbie Tires Pictures from “Navigating Mobile Robots: Systems and Techniques” Borenstein, J. Changing diameter makes for uncertainty in dead-reckoning error

  6. Skid Steering • Advantages: • Simple drive system • Disadvantages: • Slippage and poor odometry results • Requires a large amount of power to turn

  7. Synchro Drive • Advantages: • Separate motors for translation and • rotation makes control easier • Straight-line motion is guaranteed mechanically • Disadvantages: • Complex design and implementation Pictures from “Navigating Mobile Robots: Systems and Techniques” Borenstein, J.

  8. Distributed Actuator Arrays: Virtual Vehicle • Modular Distributed Manipulator System • Employs use of Omni Wheels

  9. Omni Wheels Nourkbash Mason Pictures from “Navigating Mobile Robots: Systems and Techniques” Borenstein, J. Morevac Morevac • Advantages: • Allows complicated motions • Disadvantages: • No mechanical constraints to require straight-line motion • Complicated implementation

  10. Airtrax They say that omniwheels don’t have problems….

  11. Make a Coaster with Omniwheels

  12. Tricycle Pictures from “Navigating Mobile Robots: Systems and Techniques” Borenstein, J. • Advantages: • No sliding • Disadvantages: • Non-holonomic planning required

  13. Ackerman Steering • Advantages: • Simple to implement • Simple 4 bar linkage controls • front wheels • Disadvantages: • Non-holonomic planning required Pictures from “Navigating Mobile Robots: Systems and Techniques” Borenstein, J.

  14. Magnets? (Paint Stripping/Bares)

  15. Are wheels good? • Power efficient • Constant contact with (flat) ground (no impacts) • Easy and inexpensive to construct • Easy and inexpensive to maintain • Easy to understand • Minimal steady-state inertial effects Can only go on flat terrains?

  16. Rocker Bogie Taken from Hervé Hacot, Steven Dubowsky, Philippe Bidaud http://www.robotthoughts.com/index.php/lego/archives/2007/07/20/lego-nxt-rocker-bogie-suspension/ http://www.huginn.com/knuth/blog/2007/06/24/lego-nxt-rocker-bogie-suspension/

  17. Why Robots and not people, now • Safety • 30 probes sent to Mars in the last ten years • Only 1/3 made it • Radiation • Cost • Without life support and other needs, 1 million dollars per pound • 900 pounds of food per person • MER $820 million total (for both rovers)$645 million for design/development + $100 million for the Delta launch vehicle and the launch + $75 million for mission operations • Return • Fuel • Landing

  18. Spirit and Opportunity • The rovers can generate power with their solar panels and store it in their batteries. • The rovers can take color, stereoscopic images of the landscape with a pair of high-resolution cameras mounted on the mast. • They can also take thermal readings with a separate thermal-emission spectrometer that uses the mast as a periscope. • Scientists can choose a point on the landscape and the rover can drive over to it. The rovers are autonomous -- they drive themselves • The rovers can use a drill, mounted on a small arm, to bore into a rock. This drill is officially known as the Rock Abrasion Tool (RAT). • The rovers have a magnifying camera, mounted on the same arm as the drill, that scientists can use to carefully look at the fine structure of a rock. • The rovers have a mass spectrometer that is able to determine the composition of iron-bearing minerals in rocks. This spectrometer is mounted on the arm, as well. • Also on the arm is an alpha-particle X-ray spectrometer that can detect alpha particles and X-rays given off by soil and rocks. These properties also help to determine the composition of the rocks. • There are magnets mounted at three different points on the rover. Iron-bearing sand particles will stick to the magnets so that scientists can look at them with the cameras or analyze them with the spectrometers. • The rovers can send all of this data back to Earth using one of three different radio antennas.

  19. Sprit (1/4/4)

  20. More Pictures from Spirit

  21. Rocker Bogie

  22. Lunakod: Were we first? 1969 Lunokhod 1A was destroyed at launch 1970 Lunokhod 1landed on the moon 1973 Lunokhod 2 landed on the moon In 322 days, L1 traveled 10.5km Both operated 414 days, traveled 50km In 5 years, Spirit and Opportunity 21km

  23. Did they find it? (Russian)

  24. Marsakhod

  25. Articulated Drive:Nomad • Advantages: • Simple to implement except for turning mechanism • Disadvantages: • Non-holonomic planning is required Internal Body Averaging Motors in the wheels

  26. UGCV (Crusher) [Bares/Stentz, REC]

  27. IRobot, Packbot

  28. Dragon runner (Schempf, REC)

  29. Gyrover (Brown and co.)

  30. Ball Bot, Hollis “A Dynamically stable Single-Wheeled Mobile Robot with Inverse Mouse-Ball Drive."

  31. Challenge for next Lab

  32. Framewalker: Jim2 • Advantages: • Separate actuation of translation • and rotation • Straight-line motion is guaranteed • mechanically • Disadvantages: • Complex design and implementation • Translation and rotation are excusive

  33. ? Are legs better than wheels? Legged Robots • Advantages: • Can traverse any terrain a human can • Disadvantages: • Large number of degrees of freedom • Maintaining stability is complicated

  34. Dante II

  35. Honda Humanoid

  36. Raibert’s Robots (First ones) 3D Hopper, CMU/MIT, 1984 actively balanced dynamic locomotion could be accomplished with simple control algorithms. 3D Biped, MIT, 1989-1995 Passive dynamics to help with maneivers

  37. More Raibert robots • Quadruped, 1984-1987 • Planar Quadruped (Hodgins, 1985-1990)

  38. RHexKodischek, Buhler, Rizzi Act like wheels……compliance…

  39. Sprawlita, Cutkowsky

  40. Big Dog, Boston Dynamics Quadruped robot that walks, runs, and climbs on rough terrain and carries heavy loads. Powered by a gasoline engine that drives a hydraulic actuation system. Legs are articulated like an animal’s, and have compliant elements that absorb shock and recycle energy from one step to the next. Size of a large dog or small mule, measuring 1 meter long, 0.7 meters tall and 75 kg weight. http://video.google.com/videoplay?docid=5349770802105160028&q=robot+raibert

  41. Benefits of Compliance: Robustness • Handle unmodeled phenomena • Regulate friction (e.g. on textured surfaces) • Minimize large forces due to position errors • Overcome stiction • Increase grasp stability • Extra passive degree of freedom for rolling • Locally average out normal forces (provides uniform pressure, no precise location) • Lower reflected inertia on joints [Pratt] • Energy efficiency (probably not for snakes)

  42. Whegs, Quinn No compliance….

  43. SNAKE ROBOTS: Many DOF’shttp://snakerobot.com • Thread through tightly packed volumes • Redundancy • Minimally invasive • Enhanced mobility • Multi-functional Thanks to JPL

  44. Hyper-redundant Mechanisms Mobile-trunk Free-crawling Manipulation Biology Robotic Connections Reduction Scaled Momentum Gait generation Roadmaps SLAM Coverage Climbing: Contact Distributed Manipulation (J. Luntz)

  45. OmniTread

  46. SAIC/CMU

  47. SARCOS • Still looking

  48. Biologically Inspired Gait #1:Linear Progression Biological Snakes http://youtube.com/watch?v=xUQ_SMCCPN4 • Anchors at sites - travel backwards • Symmetric movement in axial direction • Anteroposterior flexible skin • Momentum is conserved as the snake travels at a fairly constant speed/little drag

  49. Biologically Inspired Gait #2: Sidewinding http://video.nationalgeographic.com/video/player/specials/most-watched-specials/adder_peringuays_kids.html

  50. Lateral Undulation Biological Snakes • *Energy Efficiency compared to tetrapods • Jayne – comparable • Gans/Chodrow&Taylor – more • High endurance Gans http://www.youtube.com/watch?v=sembodyhZUo

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