# Medium

- and Heavy

- Duty

Powertrain
Hardware

- in

- the

- Loop 

# Test System Dec. 10, 2014

1

# Outline

• Overview of Powertrain Hardware

- in

- the

- Loop (HIL) test systems

• Test cell specifications

• Repeatability and COV

• Recognizing sources of COV

• Improvements to test system

• Test system measurements for drive

- cycle MPG

• Notes on comparisons to other test systems

2

# Vehicle GHG Evaluation: Capturing the big picture?

3

Engine
HIL Powertrain

HIL Vehicle

HDC On

- Road

Vehicle Full Simulation 

### Simulation 

### and tuning effort 

## Relative
Cost



# Hardware



# Extent Relative Uncertainty 

# Simulation
Extent

# Vehicle GHG Evaluation: 

# Capturing the big picture?

• Full simulation

– Cost and technical uncertainty high



# • Engine dyno tests

– Historical repeatability and cost understood



# • Powertrain test cell

– Repeatability and cost understood



# • Vehicle HDC

– Repeatability and cost understood



# • On

- Road vehicle

– Cost to provide acceptable repeatability/uncertainty high

4

# Another View of Various Methods to Measure



# GHG Emissions

5 Greenhouse Gas Emission Model [GEM]

HD Chassis Powertrain Test Cells

# Background on Powertrain Testing

• Capture key interactions between engine and transmission

• Evaluate powertrain as if in vehicle

• Allows for expansion to hybrid or other energy management technology

6 Conventional HD Testing: Powertrain in the Loop: Motor/Gen Battery

Internal Combustion Engine Internal Combustion Engine Transmission

# Test Cell Specifications

• Test Cell specifications similar to conventional engine dynamometer test cell

• Dynamometer sizing different than 

# conventional engine test cells

7

# Test Cell Specifications: 

# Dynamometer requirements

8



### Simplified theoretical analysis says that torque requirements in 

### low gears may be excessive, requiring very large dynamometer 1

2

3

5 4

6 7 8 9 10 

### Heavy

- duty example shown

# Test Cell Specifications:

Powertrain Torque Over Drive Cycle vs. Dyno Capacity

24

- Jun

- 2014 9



### Each drive cycle has different 

### torque capacity requirements.

Periods of highest torque demand are often very brief. 

### Heavy

- duty example shown

# Medium

- Duty Powertrain

10

# Example from Current Program: 

# Medium

- Duty Powertrain Vehicle

24

- Jun

- 2014 11



# F650 Flat Bed Tow Truck

• Cummins ISB 6.7L I6



## • 2010 compliant

– EGR, DOC,DPF,SCR



## • Allison 2200 RDS

– 5

- speed Automatic



## • Coastdown data created under separate task



## • Heavy Duty Chassis Dyno (HDC) testing under separate task

# Powertrain HIL 

# Test System Configuration

12 Pedal Position (Torque Command)

Dyno
Motor Speed Control

Driveshaft Torque/Speed Feedback Driveshaft

Speed Command

dSPACE MABX I (Vehicle simulation) Pedal, Driveshaft Speed Target Cycle Speed

# MD Powertrain HIL Test Cell at SwRI

13 445 kW DC motor/ dyno Friction brake for zero speed control i nline torque meter

Eddy current dyno for high absorption tests Powertrain

# MD Powertrain Test Cell Setup

• SwRI Heavy Duty Transient Data 

# Acquisition (HDT)

– pressures/temperatures, CAN, LAN, serial, etc.



# • DSpace Real

- Time Simulation

– enhanced GEM model for vehicle simulation



# • Horiba Raw Emission Bench

– CO 2 

### , CO, THC, and NO
x



# • LFE airflow



# • Coriolis fuel flow meter

• BG3 PFD for particulate matter
measurement

14 

## Test cell utilizes many sub

- systems that are already available for most conventional engine

- dyno test cells.

Test cell has been repeatedly reconfigured

as Powertrain or Engine test cell during this

program.

# Transient Cycles 

# considered for this study

15

CARB WHVC

PARCEL CILCC

# Transient Cycles

– 

# Decomposed as Time at Various Speeds

16 

# Differences in cycle speed demand provides breadth for study of Powertrain HIL test system

# System Validation: 

# Vehicle Speed vs Cycle

- Defined Speed

17

0 5 10 15 20 25

0 1000 2000 3000 4000 5000 6000 7000 Vehicle Speed [m/s]

Cycle Time [ msec ] 

## F650 ARB Vehicle Speed Desired
Vehicle Speed Actual
Vehicle Max Speed
Vehicle Min Speed

0 5 10 15 20 25

2550 2650 2750 2850 2950 3050 3150 3250 3350 3450 Vehicle Speed [m/s]

Cycle Time [ msec ] 

## F650 ARB Note that a “good” test is not necessarily a repeatable test. The Driver is critical to repeatability. Note that the driver could have driven a “good” test many different ways

# System Validation: 

# Powertrain Torque vs Theoretical Requirement

18 - 500 0 500 1000 1500 2000

0 100 200 300 400 500 600 700 Trans Output Torque [N - m]

Cycle Time [sec] F650 ARB Theorectical_torque N

- m Torque N

- m

- 500 0 500 1000 1500 2000

255 265 275 285 295 305 315 325 335 345 Trans Output Torque [N - m]

Cycle Time [sec] F650 ARB

– Detail of 100 Seconds Meeting vehicle load requirements depends upon minimizing vehicle speed deviations and dyno load

- control deviations.

# Repeatability: 

# Pedal Position for 5 tests

19 0 10 20 30 40 50 60 70 80 90 100

0 1000 2000 3000 4000 5000 6000 7000 Driver Pedal Position Run 1

Run 2

Run 3

Run 4

Run 5 (ARB cycle)

Here we show that the driver model is (nearly) repeating the same movements for several drive

- cycle repeated tests 0 20 40 60 80 100

2650 2670 2690 2710 2730 2750



# The software driver is repeatable

# Repeatability: 

# Vehicle speed for 5 tests

20 - 5 0 5 10 15 20 25

0 1000 2000 3000 4000 5000 6000 7000 Vehicle Speed [m/s] Run 1

Run 2

Run 3

Run 4

Run 5 (ARB cycle)

So, the software driver is driving the same every cycle, closing the loop on the required vehicle speed 

# ...If the driver is repeatable, the vehicle speed will be repeatable

# Repeatability: 

# Torque for 5 tests

21

- 500 - 300 - 100 100 300 500 700 900 1100 1300 1500 1700 1900

0 1000 2000 3000 4000 5000 6000 7000 Torque [N - m] Run 1

Run 2

Run 3

Run 4

Run 5 (ARB cycle)

The dyno

- controller is also very repeatable, leading to excellent repeatability for vehicle speed and load. 

# Repeatability is also successful for vehicle load

- 500 - 300 - 100 100 300 500 700 900 1100 1300 1500 1700 1900

2650 2700 2750 2800 Run 1

Run 2

Run 3

Run 4

Run 5

# Repeatability: 

# Exhaust Temperature for 5 tests

22

0 50 100 150 200 250 300 350 400

0 1000 2000 3000 4000 5000 6000 7000 Exhaust Temp
Run 1

Run 2

Run 3

Run 4

Run 5 (ARB cycle)



# Exhaust temperatures follow the success

of the speed and load controllers

# Repeatability: 

# Engine Coolant Temperature for 5 tests

23

70 75 80 85 90 95 100

0 1000 2000 3000 4000 5000 6000 7000 Engine Coolant Temp

Run 1

Run 2

Run 3

Run 4

Run 5 (ARB cycle) 

# Engine coolant temperature exhibited

some variation, cycle

- to

- cycle.

...these differences warranted closer study

# Repeatability:

FE Coefficient of Variance (COV) for larger numbers of tests

24 

## • Fuel Economy COV very good for CARB and WHVC cycles



## • As program expanded number and type of test cycles, it became clear that other sources of uncertainty were being experienced

Vehicle Config / Cycle 

# Fuel Economy COV

# Repeatability: Finding sources of uncertainty/poor repeatability

25 

### 7.34 7.53

7 7.1 7.2 7.3 7.4 7.5 7.6 7.7

35 55 75 95 Fuel Economy, MPG



### Transmission Temperature, degC

CAC Temperature 46C Parcel Cycle 

### 7.34

7.28

7 7.1 7.2 7.3 7.4 7.5 7.6 7.7

20 30 40 50 

### Charge Air Cooler Temperature, degC

TransmissionTemperature 42C Parcel Cycle 

## Several studies performed to locate and mitigate effects of system variables

# Key Findings

• Similar to conventional engine dyno cells, Powertrain HIL test cell repeatability can be improved by control of system variables such as:

– Coolant temperature setpoints (heat exchanger control)

– Transmission temperature setpoints (heat exchanger control)

– Charge air temperature setpoints (heat exchanger control)



# • Selection of controllable/repeatable setpoints may create drive

- cycle fuel economy differences compared to other test systems

– Powertrain HIL Test System may be slightly different than Chassis Dyno or Truck

- on - Road

– Again, these distinctions have been recognized previously for engine test cell vs Truck

- on - Road

26

# Attention to Detail

• Like Engine

- based or Chassis

- dyno

- based, Powertrain HIL must be “prepped” carefully



## – Forced DPF regeneration at regular intervals between
tests

– Several “prep” cycles run before “official” cycle

 Stabilize initial conditions and powertrain system recent history



## • Post

- test

– Review large data sets to identify repeatability issues

 Driver

 Transmission gear selection

 Aftertreatment thermal management

 Other uncontrolled variables...

27

# Repeatability:

FE COV and average fuel economy effects for various factors

Fuel Economy Effects

55 mph 65 mph CARB WHVC Utility Parcel

Add 10% Cd

- 3.7%

- 5.1%

- 0.9%

- 1.5%

- 0.3% 0.4%

Add 10% Crr

- 2.7%

- 1.3%

- 1.4%

- 1.4%

- 1.4%

- 1.0%
Add 363 Kg

- 0.5%

- 0.3%

- 2.8%

- 1.9%

- 2.1%

- 1.6%

Baseline

- - - - - - EPA Optimized 5.9% 6.7% 2.2% 4.4% 2.6% 2.1%

Minus 10% Cd 4.7% 5.0% 0.5% 2.0% 0.4% 0.8%

Minus 10% Crr 1.4% 1.0% 1.6% 2.5% 2.3% 1.5%

Fuel Economy COV

55 mph 65 mph CARB WHVC Utility Parcel

Add 10% Cd 0.66 0.11 0.09 0.09 0.30 0.27

Add 10% Crr 0.78 0.12 0.23 0.23 0.57 0.12
Add 363 Kg 0.90 0.60 0.29 0.29 0.58 0.15

Baseline 0.21 0.21 0.39 0.39 0.30 0.77
EPA Optimized 0.61 0.87 0.44 0.44 0.37 0.23

Minus 10% Cd 0.34 0.33 0.19 0.19 0.85 0.46

Minus 10% Crr 1.50 0.59 0.10 0.10 0.23 0.54

28 

### This data was 

### taken during the midpoint of the overall program.

Improvements to the test system accuracy and repeatability continued to occur throughout

program

# Another View of Fuel Economy Parametric 

# Study in a Powertrain HIL Test Cell

29 Conducted test matrix varying vehicle aero and drag coefficients and weight to study FE sensitivity CARB Cycle

Test Configuration 

## Scale of 1% Fuel Economy differences

# Ongoing Activity: 

# Heavy

- Duty Powertrain HIL System Setup

• International ProStar

– Navistar N13 13L I6

– 2010 compliant (EGR, DOC,DPF,SCR)

– Eaton UltraShift Plus LSE 16Speed AMT

– Class 8 Linehaul



## – Coastdown performed

– On road constant speed tested

24

- Jun

- 2014 30

# Ongoing Activity: 

# Heavy

- Duty Powertrain HIL System Setup

31 

## • Engine

- only shakedown tests 

## complete at 2 power ratings

• Powertrain system installed 

## and ECU, TCM communication established

• First test runs 

## completed November, 2014 

# Test cell available for tour

# Key notes for 

# Powertrain HIL Test Cell

• All driving accomplished by driver model

– Driver variability is minimized



### – Driver tuning is available

– not all cycles the same



## • Vehicle variability downstream of transmission is eliminated

– Driveshaft



### – Differential and axles

– Tires and Rolls



## • Closed

- Loop temperature control available for most subsystems

– CAC, engine coolant, transmission temp, fuel temp, etc



## • Dual

- use test cell

- Traditional engine or powertrain test system

32

# Summary

• SwRI set up and demonstrated 2 Powertrain HIL test cells under contract from EPA

– Medium

- and Heavy

- duty

– Both cells utilize conventional engine test cell equipment, reconfigured for Powertrain HIL studies



# • Preliminary results from MD Powertrain HIL indicate

– Repeatability similar to that available from conventional engine test cells (COV ~0.2

- 0.5)

 Inclusion of vehicle modeling capability, transmission, and added networking at test cell did not degrade data quality

33

# Summary

• HD Powertrain HIL test system is operational 

# and evaluation of performance and repeatability now initiated



# • Separate tasks in overall EPA program are comparing different engine/ powertrain /truck GHG measurement systems

– Engine HIL

– Powertrain HIL

– Heavy

- duty Chassis dynamometer

34