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TWiki > Main Web>PerchingProject>JumpingDesign (30 Oct 2010, MarkCutkosky)

Planning sessions

Review Jumping Mechanisms

Bioinspiration
Overview of jumping (from University of Bath, The Centre for Biomimetic and Natural Technologies; creators of Jollbot and Glumper, see below)

Leg Design and Jumping Technique for Humans, other Vertebrates and Insects

  • Thighs mass is about 20% in human and bushbabies, while lower legs and feet represents about 12%. In the locus, the femora are 14% of body mass, while the tibiae and tarsi are only 3%.
  • Weight: 70kg for humans, 0.3kg for bushbabies and 2g for the locust.
  • Leg segment 450mm for humans, 66mm for bushbabies, 25mm for locust.

Existing Jumping Robots:

  • MOWGLI
    • 3kg
    • height (standing straight): .9m
    • jumping height: .5m

(http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=1217)

  • "Grillo" Mini Robot

Functions

1 = desirable*, but not a priority
2 = more desirable upgrade from most basic jumping/takeoff (and maybe helpful to jumping), but not necessarily necessary
5 = very probably going to be crucial to successful basic jumping/takeoff

*largely driven by what we want to build, so these are definitely up for discussion

Mass

Low relative mass of the foot (5) Energy lost = (mass of foot)/(total mass) x 100% (in [Alexander 1995] they say that thighs mass is about 20% in human and bushbabies, while lower legs and feet represents about 12%. In the locus, the femora are 14% of body mass, while the tibiae and tarsi are only 3%
Low overall mass of the jumping system (5) Ideally around 75g (absolute max of 100g, assuming the plane's mass is 400g -- any heavier and it won't fly)
Able to carry payload (1) A small camera would be awesome

Jump

Efficiently convert potential energy to kinetic energy (5) "frogbot" (see second generation robot in "Minimalist Jumping Robot for Celestial Exploration") achieves 70% efficiency using the six-bar mechanism
No slippage during jump (5) Minimized slippage contributes to efficiency
Able to vary the takeoff angle (4) (So we can manually change/preset launch angle)
Able to vary the point of application of the force (on the plane) (4) (without altering takeoff angle)
Active control of the energy/force release (2)  
Load and unload the mechanism (without jumping) (1)  
Store energy (5) If we assume 100% conversion efficiency, we need to store 5.08 to 13.14 joules of energy (see June 30th on Julia's blog for calculation details). At 70% efficiency (achieved by "frogbot"), this corresponds to 7.26 to 18.77 joules. Springs or possibly SMA are probably our best bet. Pneumatics require heavy compressors.
Minimize airplane drag during takeoff (3) Drag force becomes more significant than the force of gravity at velocities just under 4 m/s
Minimize roll and yaw motion during jumping (4)  
Perform multiple jumps (5)  
Quickly loads the mechanism (3) <30seconds
Control the area traversed by the airplane during takeoff (clear off obstacles) (1)  

Flight

Low drag of the mechanism during flight (4)  
Collapsable during flight (4)  
Ability to perform acrobatics (1) similar to above function (collapsable during flight)

Landing

Able to land and favor takeoff (4)  
Load the jumping mechanism on landing (3) (at least absorb landing impact -- maybe for perching...)

Integration

Reducing redundancy (3) (minimize mass!)
Aesthetics / cool factor (4)  
Other capabilities (mobility on the ground, perching, etc) (2)  

Flexibility

Being able to takeoff from various surface type (soft, hard, smooth, rough, uneven, grass, etc) (1)  
Land and takeoff from incline surfaces (1) related to ability to change takeoff angle -- see "Jump" table above

Concepts

Jumping Mechanism Brainstorm (July 2, 2010)
IMGP5072.JPG IMGP5075.JPG

  • Rotate, collapse the wing
  • Slingshot (peg in the ground and back up)
  • Lift up and then flap down as you jump
  • Lift the plane up (tilt up) and drop to gain speed
  • Climp up something and then jump down
  • SMA wires pushing underneat the plane (soft while flying)
  • Piston
  • 4 bar linkage
  • 5-6 bar linkage
  • Whegs with extendable legs (to increase height)
  • Load the wheel backward and then take off (short runway)
  • Roll and then jump (eccentric wheel)
  • Multiple hops (resonant frequency), with whegs
  • Lazy-tongs
  • Cricket leg
  • Party thing (blow air into flat, curled paper tube and it unrolls into a cylindrical tube)
  • Use wing/tail as the spring/lever
  • Foldable structure to lift the plane

Energy Storage

  • Curve carbon fiber spring
  • Cam-loaded spring
  • Compression spring
  • Bi-stable mechanism (snap-fast) with a spring in series
  • Wait for the wind/reorient to face the wind
  • Store compressed air in the wing
  • Balloon (conical shape)

Actuation

  • SMA (power-dense, fast)
  • Use main motor for flight and for jumping
  • Explosion
  • Rocket engine
  • Inflate a balloon underneat
  • Hot air balloon to lift you up
  • Piezo to load spring (ratchet)
  • Small electric motor

Preliminary Design

Detailed design/Fabrication/Prototype

Release Mechanism

Design Requirements:
  • Release while in tention
  • Quick release
  • No premature trigger (locking)

IMGP5075.JPG IMGP5075.JPG IMGP5075.JPG

Pelican Hook

IMGP5075.JPG IMGP5075.JPG

 
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