Profiling of rough terrain - UP · Profiling methods Profiling concepts Profiled terrains...
Transcript of Profiling of rough terrain - UP · Profiling methods Profiling concepts Profiled terrains...
Profiling of rough terrainby Carl Becker
SCOPE
� Introduction
� Literature survey
� Profiling methods
Profiling concepts� Profiling concepts
� Profiled terrains
� Simulations
� Conclusion
INTRODUCTION
� Simulations are used to verify designs
� Cost effective design verification, prior to prototype building
� Compare simulation results with actual field tests
� Simulation requirements� Model – may be simplified
� Constraints
� Input data
� Simulation is nothing like recycling� Simulation => Garbage in = garbage out
� Correct input data is very important
� Model => Land Rover Defender (validated by M Thoresson)
� Input => Profile of rough terrain
INTRODUCTION
�Three profiling concepts were built and verified
�Profile a section of the Belgian with each concept profiler�Compare profiles from concept profilometers
�Displacement Spectral Densities �Displacement Spectral Densities
�Obtain profiles of frequently used rough terrains�Profiles of the rough terrains at Gerotek test facilities
�Use profile as a Road Definition File in simulation with the use of a previously validated model
�Compare simulation results with actual field tests
LITERATURE SURVEY
� Profiling methods
� Inertial profilers (2-D)
� Laser profilers (3-D)
� Aerial photography (3-D)� Aerial photography (3-D)
Profiling methods
Inertial profilers
(2-D)
Profiling methods
Inertial profilers
(2-D)
High speed profiler
Profiling methods
Laser profilers
(3-D)
Vehicle Terrain
Measurement System
�DGPS
�Inertial Measurement
Unit
�Laser scanner
Profiling methods
� Aerial
photography
(3-D)
Profiling methods
•2-D and 3-D profilometers are available to profile
smooth roads at relative high speed
•Terrains to be profiled are too rough for available
profilometers
•All profilometers have errors•All profilometers have errors
� Gyro errors
� Laser errors
� GPS errors
� Errors caused by the dynamics of vehicle
Profilometer Requirements
It is required that the profilometers are capable of
the following;
� Profile rough terrain (vertical displacements > 25
mm).mm).
� Minimum profile width of 2.5 m.
� Profilometer must be light weight and easily
transported.
� Effective profiling with minimal resources
required.
Profilometer Concepts
� Mechanical profilometer
� Photogrammetric profiling
� Laser scanner
Mechanical Profilometer
A mechanical profilometer using arms pivoted to a reference
frame on one side with small wheels on the ends in contact
with the ground, nicknamed the Can-Can machine
Tilt sensor
Profiling arms Encoder
Potentiometers
Mechanical Profilometer
�Profiles a 3 m wide section
�Resolution = 10.18 mm x 100 mm
�Profile an obstacle < 100 mm high
�Accuracy less than 5 mm
�Profiling fast and effective
Profile of Belgian paving
� Mechanical profilometer
Photogrammetric Profilometer
�Survey control points on profiled terrain (Pro Mapping)
�Calibrate camera to determine the lens distortions, focal length and size of the image
�Sequential photos are taken perpendicular to terrain a with digital camera mounted on a tripod
�Photos overlap one another by 60%
�Mapping done by CAD Mapping on a digital photogrammetric workstation
Photogrammetric Profilometer
�Profiles a 2.5 m wide section, depending on height of camera
�Resolution = 10 mm x 10 mm
�Profile an obstacle > 150 mm high
�Accuracy 3 mm to 10 mm, depending on camera
�Profiling resource intensive
-0.4-0.2
00.2
0.40.6
0.81
1.2
-0.200.2
0.40.60.81
1.21.41.6
1.8
0
0.2
0.4
Width [m]
Concept D test section
Distance [m]
Hei
ght
[m]
Profile of Belgian paving
� Photogrammetric profilometer
� Distortion in camera lens
Laser Scanner Profilometer
�Laser Distance Sensor, S80-MH-5 Data Sensor, used to measure the profile of the
terrain from a vertical distance of 2m
�The Data Sensor is mounted in a purposely build gimball which is mounted on a
tripod
�The gimball enables the Laser Distance Sensor to rotate about two perpendicular
axes. The rotation is controlled by two Stepper motors
Stepper Motors
Laser
Laser Scanner Profilometer
�Profiles a 2.4 m wide section
�Resolution = ave 60 mm x 60 mm, limited by step size
�Profile an obstacle > 150 mm high
�Accuracy 7 mm
�Profiling time consuming, laser sensitive to profiled surface
500x360x58 mm
Profile of Belgian paving
� Laser scanner profilometer
Belgian paving
Displacement Spectral Densities
DSD calculated as follows:
With
( ) ( ) 2
2xx
X FS F
Fδ=∆
With
( )
( ) 2 *
X Fast Fourier Transformof the road profile x d
F Step in Frequency
X F X X
δ
δ δ δ
=∆ =
=
Belgian paving
Displacement Spectral Densities
10-2
100
102
/cyc
les/
m]
DSD of profiled tracks
Class A roadClass D roadClass H road50m Belgian paving, Photogrammetry40m Belgian paving, Laser40m Belgian paving, Can-Can
10-3
10-2
10-1
100
101
102
10-12
10-10
10-8
10-6
10-4
Spatial Frequency [cycles/m]
Dis
plac
emen
t S
pect
ral D
ensi
ty [
m2 /cyc
les/
m]
Displacement Spectral Densities
vs. Straight line fit
10-3
10-2
10-1
/cyc
le/m
]
Belgian paving PSD, Can-Can profile
Belgian paving, Can-Can profile
Inverse Power Law,Sx
= Ax-n
0.05 cycles/m
10 cycles/m
10-2
10-1
100
101
10-7
10-6
10-5
10-4
Spatial Frequency [cycles/m]
Dis
plac
emen
t S
pect
ral D
ensi
ty[m
2 /cyc
le/m
]
Profiled Terrains
� Fatigue Track
Profiled Terrains
� Corrugations
Profiled Terrains
� Potholes
Profiled Terrains
� Ride and Handling Track
� 4.2 km long, profiled in 1 day.
1000
400 600 800 1000 1200 1400 1600 1800 2000 2200
1000
1200
1400
1600
1800
2000
Profiled Terrains
� Ride and Handling Track� Close-up on low mobility Ride and Handling Track
Profiled Terrains
� Rough Track
� Profile top Plato of Rough Track (800 m)
3200 3300 3400 3500 3600 3700
800
850
900
950
1000
Profiled Terrains
� Rough Track
� Structural stiffness of Can-Can too low
Profiled Terrains
� Rough Track� Close-up of rough track
Profiled Terrains
The Can-Can Machine is considered an efficient
profilometer due to:
� “High” profiling speed and efficiency
� Ease of data processing� Ease of data processing
� Accuracy of the profilometer
� Low operating costs
Simulation Model
� Front Suspension
Simulation Model
� Rear Suspension
Simulation Model
� Complete Model on RDF Belgian paving
Simulation Model
� Simulation validation over a trapezoidal bump
(M Thoresson)
Simulation Model
Actual test @ 15 km/h Simulation @ 15 km/h
Simulation Model
� Simulation results FFT unfiltered
0.25
0.3
Simulation FFT and Land Rover FFT of Right Rear Body @ 15 km/h
Simulation Right Rear Body
Land Rover Right Rear Body
0 2 4 6 8 10 12 14 16 18 20
0
0.05
0.1
0.15
0.2
Frequency [Hz]
Am
plitu
de [
m]
Simulation Model� Simulation results filtered FFT (8 Hz low-pass)
0.3
0.35
Simulation FFT and Land Rover FFT of Right Rear Body @ 15 km/h
Simulation Right Rear Body
Land Rover Right Rear Body
0 1 2 3 4 5 6 7 8 9 10
0
0.05
0.1
0.15
0.2
0.25
Frequency [Hz]
Am
plitu
de [
m]
Simulation Model
Simulation Model
BS 6841
[m/s2]
Ride comfort
>2.5 Extremely
uncomfortable
RMS of the vertical accelerations
2.5
3
3.5
RMS_SIM_LFuncomfortable
1.25-2.5 Very
uncomfortable
0.8-1.6 Uncomfortable
0.5-1.0 Fairly
uncomfortable
0.315-0.63 A little
uncomfortable
<0.315 Not
uncomfortable
0
0.5
1
1.5
2
15 26 40 57 73
Speed [m/s]
RM
S [
m/s
^2]
RMS_SIM_LF
RMS_Landy_LF
RMS_SIM_RR
RMS_Landy_RR
RMS_SIM_LR
RMS_Landy_LR
Conclusion
� Three profilometers verified
� Can-Can Machine most efficient profilometer
� Obtained accurate 3-D profiles of frequently
used test tracksused test tracks
� Straight line approximation for DSD not valid
approximation
� Good correlation between actual tests and
simulations on profiled terrain
Questions?