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Experimental Evaluation of the Scale Model Method to Simulate Lunar Vehicle DynamicsAs compared to driving on Earth, the presence of lower gravity and uneven terrain on planetary bodies makes high speed driving difficult. In order to maintain ground contact and control vehicles need to be designed with special attention to dynamic response. The challenge of maintaining control on the Moon was evident during high speed operations of the Lunar Roving Vehicle (LRV) on Apollo 16, as at one point all four tires were off the ground; this event has been referred to as the Lunar Grand Prix. Ultimately, computer simulation should be used to examine these phenomena during the vehicle design process; however, experimental techniques are required for the validation and elucidation of key issues. The objectives of this study were to evaluate the methodology for developing a scale model of a lunar vehicle using similitude relationships and to test how vehicle configuration, six or eight wheel pods, and local tire compliance, soft or stiff, affect the vehicles dynamic performance. A wheel pod consists of a drive and steering transmission and wheel. The Lunar Electric Rover (LER), a human driven vehicle with a pressurized cabin, was selected as an example for which a scale model was built. The scaled vehicle was driven over an obstacle and the dynamic response was observed and then scaled to represent the full-size vehicle in lunar gravity. Loss of ground contact, in terms of vehicle travel distance with tires off the ground, was examined. As expected, local tire compliance allowed ground contact to be maintained over a greater distance. However, switching from a six-tire configuration to an eight-tire configuration with reduced suspension stiffness had a negative effect on ground contact. It is hypothesized that this was due to the increased number or frequency of impacts. The development and testing of this scale model provided practical lessons for future low-gravity vehicle development.
Document ID
20170000950
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Johnson, Kyle
(NASA Glenn Research Center Cleveland, OH United States)
Asnani, Vivake
(NASA Glenn Research Center Cleveland, OH United States)
Polack, Jeff
(NASA Glenn Research Center Cleveland, OH United States)
Plant, Mark
(Youngstown State Univ. OH, United States)
Date Acquired
January 31, 2017
Publication Date
September 12, 2016
Subject Category
Engineering (General)
Lunar And Planetary Science And Exploration
Numerical Analysis
Report/Patent Number
GRC-E-DAA-TN32423
Report Number: GRC-E-DAA-TN32423
Meeting Information
Meeting: International Society for Terrain-Vehicle Systems (ISTV) Americas Regional Conference
Location: Detroit, MI
Country: United States
Start Date: September 12, 2016
End Date: September 14, 2016
Sponsors: International Society for Terrain-Vehicle Systems
Funding Number(s)
CONTRACT_GRANT: NNC14VH93P
WBS: WBS 647280.04.03.20
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
Moon
wheel
exploration
Mobility
tire
traction
Mars
roving vehicle
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