1. N. Ligterink, R. Cuelenaere
RCG, 8 September 2014
N. Ligterink, R. Cuelenaere

2. Random Cycle Generator chronology
RCG, 8 September 2014
Random Cycle Generator chronology
alpha version
specifications from the Commission
alpha version distributed
feedback:
minor problems with cycle generation and signal quality
further development derived from RDE-PEMS development:
fixed selection from the available options in the alpha version
cycle requirements: alignment with RDE trip requirements
shift from “time-based” to “distance-based”
Validation:
drivability
representativeness
Add-ons….
current status
follow-ups

3. RCG components distance distribution urban/rural/ motorway
RCG, 8 September 2014
RCG components
distance distribution
urban/rural/
motorway
vehicle information
WLTP database
probabilities
of driving
behaviour
random
cycle generator
constraints and boundary conditions
cycle validation
driving cycles
check
testing
(outside project scope)
method validation

4. Methodology Based on data from WLTP database (European driving)
RCG, 8 September 2014
Methodology
Based on data from WLTP database (European driving)
Markov chain approach:
probabilities of changing acceleration and velocity band
stochastic approach
two time scales:
seconds (for acceleration)
minutes (for average velocity)
Restrictions from vehicle and test limitations (i.e. maximal power)
Each cycle to cover urban, rural, and motorway driving:
derived from the RDE-PEMS trip requirements
transitions between the ten velocity bands:

5. Markov matrix current state region of high probability start braking
RCG, 8 September 2014
current state
when decelerating
remain decelerating
input
region of high probability
start braking
deceleration
driving at a constant velocity
low probability
next state P
selection
start accelerating
when accelerating
remain accelerating
acceleration
low probability
Markov matrix
deceleration
acceleration
typical periods (2-10 seconds) of accelerations in a real-world driving

6. Random cycles? Different speed profiles (visual) Statistical analyses
RCG, 8 September 2014
Random cycles?
Different speed profiles (visual)
Statistical analyses

7. Statistical analyses of generated cycles average velocity over cycle
RCG, 8 September 2014
average velocity over cycle
velocity distribution in road types
urban
rural
motorway
distance between stops
Statistical analyses
of generated cycles

8. Open issues RDE-PEMS trip requirements are not cycle requirements:
RCG, 8 September 2014
Open issues
RDE-PEMS trip requirements are not cycle requirements:
>120 minutes is too long on a chassis dynamometer
short times, with equal distance, gives a very short motorway part
gear shift strategies:
free choice/OEM/GSI
Heinz Steven tool (WLTP)
fixed velocities (NEDC)
fixed velocities in power-to-mass classes (CADC)
delayed gear shifts during acceleration (TNO-approach)
driver assistance:
difficult to “follow a line” on the screen: driving simulation?

9. Maximum cycle duration? Change distance per road type?
RCG, 8 September 2014
Reflections?
Maximum cycle duration?
Change distance per road type?

10. Open issues Preferences?
RCG, 8 September 2014
Open issues
RDE-PEMS trip requirements are not cycle requirements:
>120 minutes is too long on a chassis dynamometer
short times, with equal distance, gives a very short motorway part
gear shift strategies:
free choice/OEM/GSI
Heinz Steven tool (WLTP)
fixed velocities (NEDC)
fixed velocities in power-to-mass classes (CADC)
delayed gear shifts during acceleration (TNO-approach)
driver assistance:
difficult to “follow a line” on the screen: driving simulation?
Preferences?

11. Next phases Beta-version and draft report asap
RCG, 8 September 2014
Next phases
Beta-version and draft report asap
Concept for Validation: TUG end ‘14
Legal text early ‘15
Validation tests (outside scope project) early ‘15

12. RCG, 8 September 2014
Back up slide

13. Alpha-version - Input to the random cycle generator
RCG, 8 September 2014
Alpha-version - Input to the random cycle generator
examples:
Prated = 82 kW
M = kg
F0 = 153 N
F1 = N/[km/h]
F2 = N/[km/h]2
physical vehicle limitations
based on type-approval data:
test mass
rated power
road-load values
chassis dynamometer restrictions (optional)
avoiding tyre slip, by limiting maximal deceleration
cycle limitations: (optional)
total duration (# seconds)
percentages, and order, of urban/rural/motorway(/ex)
amin > - 2 m/s2
Ncycle = 1800 sec
urban  rural  motorway
urban = 27% [distance]
rural = 31% [distance]