introduction to roving vehicles - university of...

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Introduction to Roving Vehicles

• Brief overview of lunar surface environment• Examples of rover types and designs• Steering systems• Static and dynamic stability

© 2009 David L. Akin - All rights reservedhttp://spacecraft.ssl.umd.edu

1

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Lunar Highlands (as imagined in 1950’s)

2

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Lunar Highlands (reality)

3

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Lunar Regolith• Broken down from larger pieces over time• Major constituents

– Rock fragments– Mineral fragments– Glassy particles

• Local environment– 10-12 torr– Meteorites at >105 m/sec– Galactic cosmic rays, solar particles– Temperature range +250°F – -250°F

4

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Regolith Creation Process

• Only “weathering” phenomenon on the moon is micrometeoritic impact!

• Weathering processes– Comminution: breaking rocks and minerals into smaller

particles– Agglutination: welding fragments together with molten

glass formed by impact energy– Solar wind spallation and implantation (miniscule)– Fire fountaining (dormant)

5

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

JSC-1 Simulant

• Ash vented from Merriam Crater in San Francisco volcano field near Flagstaff, AZ

• K-Ar dated at 150,000 years old ± 30,000• Major constituents SiO2, TiO2, Al2O3, Fe2O3, FeO,

MgO, CaO, Na2O, other <1%• Represents low-Ti regolith from lunar mare• MLS-1 simulant (U.Minn.) preferred for simulation

of highland material

6

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Surveyor

• Seven mission May 1966 - January 1968 (5 successful)

• Mass about 625 lbs• Surveyor 6

performed a “hop”– November 1967– 4 m peak altitude,

2.5 m lateral motion

7

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Lunar Roving Vehicle

• Flown on Apollo 15, 16, 17• Empty weight 460 lbs• Payload 1080 lbs• Maximum range 65 km• Total 1 HP• Max speed 13 kph

8

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Lunakhod 1 and 2

• Soviet lunar rovers– 2000 lbs– 3 month design lifetime

• Lunakhod 1– November, 1970– 11 km in 11 months

• Lunakhod 2– January, 1973– 37 km in 2 months

9

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Mars Pathfinder

• Sojourner rover flown as engineering experiment

• 23 lbs, $25M• Design life 1 week• Survived for 83 sols

(outlived lander vehicle)• Total traverse ~100 m

10

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Mars Exploration Rovers

• Two rovers landed on Mars in January 2004

• Design lifetime 90 days, 1 km

• Both at 1-year mark– Spirit 4030 m– Opportunity 2075 m

11

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Skid-Steer Rover (ET)

12

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Electric Tractor (JSC)

13

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

ET “Suspension”

14

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

ET in Hilly Terrain

15

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Static and Dynamic Stability Envelope

Stability Region

h

xt

x!

16

B

W

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Weight on the Wheels

h xt

17

Ff

Fr

r

!mg

B

!forces about rear axle

Ff = mg!"

B!xtB

#! h

B tan !$

!forces about front axle

Fr = mg!

xtB + h

B tan !"

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

ET Science Trailer Suspension System

18

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

SCOUT Suspension and Steering System

19

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Nomad (CMU)

20

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Nomad in Rough Terrain

21

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Nomad Transforming Chassis

22

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Nomad Chassis/Steering System

23

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Steering Schemes

24

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Nomad Steering Schemes

25

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Marsokhod (in NASA Ames

26

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Marsokhod Chassis

27

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Robby (JPL)

28

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Ratler (Sandia Labs)

29

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Split-Body Rovers (Sanida Labs)

30

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Rocky

31

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Rocky 4

32

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Rocky 7

33

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Sojourner

34

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

FIDO (JPL)

35

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

K10 (Small Support Rover)

36

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

SCARAB (Drilling Robot)

37

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Apollo Lunar Roving Vehicle

38

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Electric Tractor and Chariot (JSC)

39

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

SCOUT (JSC)

40

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Chariot (Mobility Chassis)

41

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Chariot B Climbs a Boulder Field

42

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

ATHLETE (JPL)

43

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Walking Robots

44

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Scorpion King (JSC)

45

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Dynamic Stability Conditions

h

mg

mdV

dt

mg

mV 2

R

!crit,! !crit,t

!crit,! = 29.7 deg !crit,t = 40.6 deg

46

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Effects of Linear Acceleration

“0-60” (sec) Accel (m/sec) Apparent G angle (Earth)

Apparent G angle (Moon)

30 0.89 5.2 29.220 1.34 7.8 40.015 1.79 10.3 48.210 2.68 15.3 59.28 3.35 18.9 64.56 4.47 24.5 70.35 5.36 28.7 73.4

47

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Linear Deceleration from 15 km/hr

Stopping distance (m)

Deceleration (m/sec^2)

Apparent G angle (Earth)

Apparent G angle (Moon)

20 0.43 2.5 15.215 0.58 3.4 19.912 0.72 4.2 24.310 0.87 5.1 28.58 1.09 6.3 34.16 1.45 8.4 42.14 2.17 12.5 53.62 4.34 23.9 69.8

48

Introduction to Roving VehiclesENAE 483/788D - Principles of Space Systems Design

U N I V E R S I T Y O FMARYLAND

Effects of Slopes on Stability

mg

mdV

dt

!crit,t

mg

mV 2

R

!crit,!

49