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NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR) Bill Bluethmann NASA/Johnson Space Center ICRA 2010 May 3, 2010

NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

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NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR). Bill Bluethmann NASA/Johnson Space Center ICRA 2010 May 3, 2010. Overview. FRED Overview Chariot Chassis Overview Focus: The Chariot Active Suspension. Flexible Range Exploration Device. - PowerPoint PPT Presentation

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Page 1: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

Bill Bluethmann NASA/Johnson Space Center

ICRA 2010May 3, 2010

Page 2: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

Overview

• FRED Overview • Chariot Chassis Overview• Focus: The Chariot Active Suspension

Page 3: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

• Pressurized Mobile Habitat consisting of: – Small Pressurized Rover cabin– Chariot chassis

• Crew explores in shirt sleeves• Access to space through suit ports

– No airlock– Direct access to suits from cabin– EVA in 15 minutes vs. 4 hours on Space

Station• Nominal operations: 2 crew for 3, 7 or

14 days– 4 crew for up to 24 hours– Field tested 3 days in 2008, 14 days in

2009

Flexible Range Exploration Device

Concept

Page 4: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

• Features:– 2 person cockpit– Redundant driving stations– Separate crew areas with privacy curtains– Storage for up to 14 days– Water system – Waste control system– Exercise devices– Hatches with docking ports– Aft driving station– Aft enclosure for suit dust and thermal

protection– Solar particle event protection

• Currently two (unpressurized) models in 1st generation series

Flexible Range Exploration Device

Page 5: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

Video – Field Testing Northern Arizona, Sept 2009

Page 6: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

Overview

• FRED Overview • Chariot Chassis Overview• Focus: The Chariot Active Suspension

Page 7: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

• Goal: – Challenge the conventional

wisdom of crew rovers• Approach: – Develop system full of

features– Prototype, prototype,

prototype– Allow team the flexibility to

try new ideas and concepts

Chariot Chassis

Page 8: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

• Six wheeled rover • Each wheel module 3 degrees-of-

freedom– Active suspension– Steering with continuous turn (crab

drive)– 2 speed transmission

• Lithium-Ion batteries– 2x18 kW-hr– Plug in electric vehicle

• Capable of being driven by on-board crew, teleoperation and ground control

Chariot Chassis

Page 9: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

Chariot Chassis

• Designed as a modular chassis carrying a variety of payloads– Crew in pressurized suits, standing up,

Chariot style– Configured as a flat deck for general

purpose payloads– Small pressurized rover cabin– Science and surveying instruments– Supplementary power

• Currently two models in 1st generation series

• Developed by Human Robotics Systems Project and NASA’s ETDP Office

Page 10: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

Video – Field Testing Northern Arizona, Sept 2009

Page 11: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

Overview

• FRED Overview • Chariot Chassis Overview• Focus: Chariot Active Suspension

Page 12: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

• Passive– Most consumer vehicles– Trading comfort and performance

• Adaptive and Load Leveling– Able to vary ride height, pitch and roll of vehicles– Often using air springs or oleo-pneumatic systems

• Semi Active– Actively control damping rates– Frequently high latency systems

Vehicle Suspension System Review

Page 13: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

• Low Bandwidth Active– Passive and active elements in series– Frequency responses on order of 10 hz– Chariot suspension falls in this

classification

• High Bandwidth Active– Passive and active elements in parallel– Frequency responses on order of 100

hz

Vehicle Suspension System Review

Bose Active Suspension

U. Texas – CEM

Page 14: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

Chariot Chassis Active Suspension

Springs/Dampers

Absolute Position Sensors

RA Gear Reducer/Motor/Brake

Ball Screw

Rails

Upper Arm

Lower Arm

Active Yoke

• Passive suspension in series with active components

• Passive suspension is traditional– Dual control arms– Coil over shocks

• Active suspension sets position of the lower control arm– Allowed each wheel module to be

raised/lowered– The vehicle can operate with any single

wheel module lifted• Sensing on motor, ball screw, control arms• Motor brake enables suspension to be

locked out

Page 15: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

• Position control mode– Control ride height, roll and pitch

• Compliance control mode– Extends range of passive springs through programmable virtual

springs– Ground force is proportional to displacement from desired

position (Hooke’s law)– Reduces impulses to chassis – Allows vehicle to conform to terrain– Performance limited by top speed of motor/gear set

• Fully tunable for various vehicle loading and performance• Plus multiple off-nominal modes

Chariot Chassis Active Suspension:Control System

Page 16: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

• Lower chassis for crew ingress/egress• Raise chassis extra ground clearance• Redundancy• Leveling against gravity

– While driving– At rest

• Improving ride comfort• Steering assist• Getting out soft soil• Docking• Site preparation/Bulldozing• Holding a constant force to a single wheel

Applications of Active Suspension

Page 17: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

Active Suspension Videos

Getting out of Soft SandAuto-leveling

Berm Building in Central WashingtonTerrain at JSC Rockyard

Page 18: NASA’s Flexible Range Exploration Device - FRED(aka LER; aka SPR)

Active Suspension Videos

Capability Sequence