Modeling, Simulation, and Power for the Polar Seismic TETwalker

1
Modeling, Simulation, and Power for the Polar
Seismic TETwalker

• Bryce Carmichael
• Elizabeth City State University
• Ivan Ruiz
• University of Puerto Rico at Mayaguez
• Unquiea Wade
• Elizabeth City State University
• July 23, 2007

2
Outline

• NASA TETwalker
• Seismic Sensors
• Mobility and Deployment Simulations
• Detailed Modeling
• Power Investigations
• Conclusions and Future Work

3
NASA TETwalker

• Developed at NASA Goddard Space Flight Center
• Tetrahedron shape made of extending struts and
  nodes
• Travels by moving its center of gravity to topple
• Future explore areas other than Earth

www.space.com ants.gsfc.nasa.gov
4
Project Goals

• Integrate polar seismic surveying into TETwalker
  robot design
• Simulate the deployment and retrieval
• Geophone and broadband seismometer
• Study robot mobility (toppling)
• Detailed models of designs
• Investigate potential power sources
• Small physical demonstration prototype

5
Seismic Sensors
Geophone Element Geophone Case
6
Seismic Sensors
Geophone and Spike Several
Deployed
7
MCS.visualNastran 4D

• Integrates motion, animation, and analysis in a
  modeling application
• Real life dynamics (physics and stress)

8
Initial Design
9
Improved Design
10
Seismic Sensor Deployment

• Vertical center strut plants and retrieves the
  seismic sensor by extending and shortening its
  length
• Always an upright strut for deployment
• Timing of strut movement is critical
• Moving one strut requires several other struts to
  also change in length and pivot at joint

11
Actuator Configuration
12
Deployment and Retrieval Simulation
Upright / ready position
Geophone deployed
Geophone Retrieved
13
Deployment and Retrieval Simulation
14
Mobility Simulation

• Purpose study dynamics of single topple
• One actuator required to extend out
• Attached actuators also must lengthen
• Linear actuator properties
• Actuator extends itself enough to turn the
  TETwalker over while pulling another node in its
  direction

15
Actuator Configuration
16
Single Topple Simulation
Strut extension
Pull other node up
Upright position
17
Single Topple Simulation
18
Modeling and Simulation Challenges

• Node-strut joint choice
• Actuator timing
• Dynamic System
• When one strut moves, many struts have to move
  and pivot at joint
• Toppling
• Slanted surfaces
• Weight of nodes

19
Detailed Modeling

• Node design
• 12-TETwalker design
• 4-TETwalker design
• Broadband seismometer application
• L.A.R.A (Lander Amorphous Rover Antenna)
• Physical prototype demonstration

20
TETwalker - Nodes

• Traction node

• Geophone node

21
12-TETwalker
22
4-TETwalker

• Upright Position

• Deployed Position

23
4-TET Center Node

• Normal View

• Exploded View

24
4-TET Second Design

• Upright Position

• Deployed Position

25
4-TET Alternate Center Node
26
4-TET Third Design

• Underneath View

• Above View

27
4-TET Gimbaled Deployment

• Flat Surface

• Inclined Surface

28
Alternate Sensor Package Broadband Seismometer

• Stowed

• Deployed

29
4-TET Broadband Seismometer

• Flat Surface

• Inclined Surface

30
Swarm Concept

• Small Array

• Large Array

Medium Array
31
L.A.R.A Concept(Lander Amorphous Rover Antenna)
Clark et al LARA
32
Seismic L.A.R.A Design
Side View
33
Seismic L.A.R.A Design
Above Views

• Excluding center nodes

• Including center nodes

34
Physical Prototype Demonstration
35
Polar Seismic TETwalker Power

• TETwalker power aspects
• Importance of power sources
• Selected power sources
• Solar
• Wind
• Vibration
• Combination of power sources

36
TETwalker Power Aspects
Mobility

• Obstacles
• Long distance traverse
• Various terrains
• Various snow conditions

Sustainability

• Self-fueling
• Power redundancy
• Conserve power
• Protect exposed sensors

www.space.com ants.gsfc.nasa.gov
Functionality

• Seismic deployment
• Data collection
• Power management
• Communication

37
Energy Harvesting

• Common Sources of Energy Harvesting
• Mechanical Energy
• From sources such as vibration, mechanical stress
  and strain
• Thermal Energy
• Waste energy from furnaces, heaters, and friction
  sources
• Light Energy
• Captured from sunlight or room light via photo
  sensors, photo diodes, or solar panels
• Electromagnetic Energy
• From inductors, coils and transformers
• Natural Energy
• From the environment such as wind, water flow,
  and solar

38
Power Source Requirements

• Feasible in polar climate
• Surface characteristics
• Environmental enclosure
• Mechanical issues
• Materials for polar regions
• Must produce adequate amount of power

39
Solar Power

• Solar power is gathered using radiation that is
  released from the sun
• Photovoltaic cells are devices that convert solar
  energy into electricity
• By using photovoltaic material such as silicon,
  the TETwalker can directly convert sunlight into
  electricity
• Photovoltaic cells can therefore supply power to
  the TETwalker

http//www.maproyalty.com/solar.html
40
PowerFilm Solar Panel

• Challenges of using Solar Power
• Durability
• Durability is one of the first concerns with
  using solar panels on rough terrains and in cold
  weather
• Energy storage issue
• A battery can be used for storage and is located
  in each node adjacent to the solar panels

http//www.powerfilmsolar.com/products/index.htm
Flexible and rollable solar panels
41
Solar-Powered Seismic TETwalker

• The TETwalker has a solar panel on every side
  except deployment side (open for geophone
  deployment)
• Not all solar faces will be exposed to direct
  sunlight
• Only one is guaranteed at all times to be exposed
  to sunlight.
• Solar panels serves two different purposes for
  the TETwalker
• 1) Power
• 2) Environmental protection

42
Wind Power

• Wind energy can be sustained over a long period
  of time because wind can be collected during any
  season or time of the day
• Wind power has an advantage over solar power as
  solar power needs a direct source of sunlight
• Horizontal and vertical wind turbines
• The rotor is connected wind shaft, which spins
  the generator and the generator converts the
  mechanical energy into electricity

43
Trade Study Rotor Size vs. Power
44
Wind-Powered Seismic TETwalker
Vertical wind turbine applied to the top node
Vertical wind turbine on the deployment strut of
the TETwalker
Another wind turbine option on TETwalker
deployment strut
45
Vibration Energy

• Two types of vibration free and forced
• Using a electromagnetic generator could help as a
  energy harvesting device
• Size of electromagnetic generator 100 mm3
• 120 nW at frequencies from 1.3 to 9.5 kHz
• Surface temperature is one challenge that effects
  the electromagnetic generator because of freezing
  to the nodes and internal components that can
  cause failure of the electromagnetic generator
• As the TETwalker topples for mobility, it can
  harness energy from resulting vibrations

Electromagnetic generator, including a coil
(brown) placed between four magnets (blue)
surrounded by a silicon structure (yellow)
46
Electromagnetic Generators Inside Nodes
Side View
Top view
47
Combination of Power Sources

• Can use multiple power sources at same time
• All three power sources would give TETwalker more
  power
• Exact power needs not yet fully determined

Vertical wind turbine powered
Solar powered
All three at same time
Vibration powered
48
Conclusion

• 4-TETwalker robot represents a good platform for
  seismic sensor deployment and retrieval
• Experiments deploying and retrieving geophone in
  polar environment using TETwalker needed
• Some of the investigations of power sources have
  proven that they are insufficient to use in the
  TETwalkers architecture

49
Future Work

• Further simulation of the dynamic toppling motion
  needed for more efficient movement
• Further investigations will take place with
  respect to finding other adequate power sources
  such as hydrogen extraction, use of ferroelectric
  materials, and future wireless power
• A trade study will be conducted of the various
  power sources with respect to the polar
  environment. In this trade study, the power gain
  and the power loss will be compared
• Physical prototype for testing in polar
  environment

50
Acknowledgements

• CReSIS
• Dr. Sivaprasad Gogineni
• Faculty Mentor Dr. Arvin Agah
• Graduate Student Mentor Chris Gifford

51
Any Questions?
52
(No Transcript)