1. Robotic Locomotion Howie Choset 16-311

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 Advantages: Allows complicated motions
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 Advantages: Disadvantages: No sliding
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

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? In 322 days, L1 traveled 10.5km
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. Legged Robots ? Are legs better than wheels? Advantages:
Can traverse any terrain a human can
Disadvantages:
Large number of degrees of freedom
Maintaining stability is complicated
Are legs better than wheels? ?

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,
Passive dynamics to help with maneivers

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

38. RHex Kodischek, 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.

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’s http://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
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

50. Lateral Undulation Biological Snakes
Propulsion by summing the longitudinal resultants of posterolateral forces
Momentum is conserved
Efficiency* increases with lower sliding friction
Used for traversing flat clear ground with some irregularities
*Energy Efficiency compared to tetrapods
Jayne – comparable
Gans/Chodrow&Taylor – more
High endurance
Gans

51. Concertina Locomotion
Biological Snakes
Robotic Snakes
Uses static friction
Energy inefficient (7X)* due to stop and go movement
Tree climbers use some form of concertina
Gans
*Jayne
Concertina in 3D
Hirose

52. NXT Snake

53. Are snakes better than legs?

54. Helicopter Lab First autonomous helicopter using vision.
Best dynamic performance for “big” helicopters.
Best digital terrain maps. 13 cm accuracy. Mapped flight 93 site.

55. DepthX Wettergreen, Kantor, Fairfield, NASA

56. ShallowX: Kantor, Choset