Climbing Feet for RiSE

1
Climbing Feet for RiSE

• June 14, 2004
• Miguel Piedrahita
• BDML

2
Overview of Future Climbing Foot Development

• Long-term goals
• Sufficient shear and normal forces for dynamic
  vertical climbing, on a variety of surfaces
• Effective attachment and detachment
• Integration of dry adhesives with spines and
  perhaps other mechanisms
• Integrated sensing
• Short-term needs
• We need to demonstrate effective climbing with
  the RiSE platform for key dates (August, October)!

3
What do we need for success in Aug/Oct?

• Video which shows progress towards vertical
  climbing on a variety of surfaces
• Show clear integration path of innovations from
  demonstration platform

4
Do we need adhesion?

• Based on location of CM and rear feet, we can
  stand on 58 deg slope without adhesion.
• Could we climb on a slightly flatter slope?
• Still need lots of shear force!
• Is that good enough for Aug/Oct?

58.0 deg
5
Surfaces
Surface Type Soft (penetrable) Rough (impenetrable) Smooth (impenetrable)
Examples Cork board, soft woods Concrete, hard woods Glass, metal, painted wall
Good climbing strategies Claws, spines with little compliance Claws, spines with high compliance Dry adhesives, PSA, friction pads
Original M18 goals 90 deg 60 deg 30 deg
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Specialized Feet for each surface?

• Easiest way to achieve good climbing on these
  three types of surfaces is to design a separate
  foot for each surface!
• Soft surface Larger, stiffer claws and spines
• Rough surface Delicate, individually sprung
  claws and spines
• Smooth surface PSA and friction pads
• Will RiSE researchers and DARPA buy into this
  approach?
• Not a very elegant solution, will lead to
  integration challenges in the future.

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Single Climbing Foot for all Surfaces?

• Requirements
• Foot-level Compliance
• High yaw compliance to deal with changing foot
  angle during stroke due to 4-bar kinematics
• Some pitch roll compliance to conform to
  surface
• Effectively combine several adhesion/shear
  mechanisms
• OR
• Develop a single adhesion/shear mechanism which
  will work on all surfaces

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Combine several mechanisms?

• Retractable spines/claws
• Push/pull cables, SMA
• Spines/claws with changing compliance
• Full-foot pivoting to engage different foot
  surfaces
• R/C servo or SMA actuation
• Requires smart actuation (surface-dependent)

Surface with firm spines
Surface with compliant spines adhesive pad
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Single Mechanism for all surfaces?

• Clever sprung claw design, like Motos
  hummingbird foot
• Maximize penetration on soft surfaces
• Minimize push-off force on smooth surfaces

10
What needs to be done

• Decide on mechanism(s) to include in foot
• Consider front/rear foot specialization!
• Test current foot designs on test track
• Measure maximum adhesion and shear force from
  each foot design
• Do different feet have different optimum
  trajectories?
• FEA and hand calcs to determine good geometries
  for polyurethane or dry adhesive pads
• FEA and hand calcs to develop flexures