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U N I V E R S I T Y C O O P E R AT I O N
U N I V E R S I T Y C O O P E R AT I O N
FlexECU Gets
Smart
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Successful collaboration between students at Esslingen University of Applied Sciences
and ETAS specialists
In the context of two theses at the Esslingen University of Applied Sciences, a five-month collaboration
with ETAS engineers was dedicated to the development and testing of the software for the freely programm-
By Prof. Dr.-Ing. Gregor Rottenkolber, Stefan Matthes,
able FlexECU engine control unit for the operation of a Smart turbocharged gasoline engine. The project
and Philipp Neef, Esslingen University of Applied Sciences;
involved software development on various ETAS tools and subsequent testing on an ETAS LABCAR
Dr.-Ing. Markus Kasper, ETAS
Hardware-in-the-Loop testing system (Figure 1).
FlexECU
Figure 1:
From left to right:
Philipp Neef,
Stefan Matthes,
and Prof. Dr.-Ing.
Gregor Rottenkolber.
LLSW interface
Low level software (LLSW)
Lambda
Exhaust
system
Manifold pressure
Air mass
Air
system
Desired
manifold pressure
Pedal
position
Engine
speed
increasingly important field of mechatronic systems in propulsion technology.
FlexECU deployment
Esslingen University works closely
with the auto industry, with its main
educational objective being the training of competent, team-oriented engineers in a practical setting. Because
today’s engine controls − at once
complex and cutting-edge − represent an important core value for
both OEMs and the supply industry, a
thorough understanding of electronic
control units comprises an essential
component in the training of future
engineers.
Regretfully, universities and suppliers
are not always capable of procuring
or accessing production ECUs for the
purpose of conducting realistic engine
trials outside a vehicle, and for testing
their own proprietary technological
approaches. A viable alternative is
offered with the FlexECU, an open
and economical ECU platform for
the on-target system development
of new control concepts.
The FlexECU currently consists of
two variants, which are based on
production-ready versions of Bosch’s
world-class compression ignited
(diesel) and spark ignited (gasoline)
engine ECU hardware with Infineon
TriCore microcontroller.
Fuel
system
Throttle valve position
Wastegate position
Current load
Torque
structure
Ignition
system
Ignition efficiency
Actuators
The completion of both graduate
theses provides the prerequisite for
running the engine on the test
bench at Esslingen University. This auspiciously successful first step in the
collaboration between ETAS and
Esslingen University is seen as the
starting signal for future function
developments and calibrations involving the FlexECU. For this device,
ETAS provides an application that
permits the gathering of valuable experiences along with extending the
function library of building blocks for
engine projects. With this project, the
internal combustion engines lab at
the Automotive Engineering Faculty
trains its educational focus on the
Injection time
Lambda correction
Ignition angle
Actuators
Engine
LABCAR
Sensor
simulation
Actuator
signal
record
GEVM
Intake pressure
Exhaust
system
Air/fuel ratio
RPM
Engine speed
system
Turbo
charger
Energy
Mass flow
exhaust gas
Manifold
pressure
Mass flow
air
Combustion
system
Engine
torque
Low level software (LLSW)
ASCET model
LLSW interface
Driver
Mass flow
injection
Intake
system
Throttle
position
Ignition angle
Fuel
system
Injection
time
Figure 2:
Overview of
engine control
functions and
testing system.
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U N I V E R S I T Y C O O P E R AT I O N
U N I V E R S I T Y C O O P E R AT I O N
Loop (HiL) system. This ensures that
the engine will be operated only after
both correct pre-calibration and successful testing of the software have
been completed (Figure 2).
The project
As part of a collaboration between
the faculties for Information Technology and Automotive Engineering at
Esslingen University, and under the
aegis of advisors Prof. Dr.-Ing. Hermann Kull and Prof. Dr.-Ing. Gregor
Rottenkolber and support from ETAS,
the FlexECU is undergoing a stepwise
adaptation to a three-cylinder Smart
gasoline engine (Figure 1). The project
contact at ETAS is Dr.-Ing. Markus
Kasper at Application Engineering
Services. The first objective of the cooperation project is the development
and implementation of control functions, along with their execution on
the ECU. The device is then tested on
the HiL system for subsequent mating
to the actual engine on the test bench.
At the same time, the project also
makes it possible to test the tool
chain, from the modeling environment to implementation onboard
the ECU and connectivity options for
various sensor and actuator types,
to the FlexECU’s basic software. Concurrent with testing, a validation of
the engine control is carried out on
the ETAS LABCAR Hardware-in-theFigure 3:
Interaction and
deployment of
development
tools.
Software development using ASCET,
EHOOKS, and INCA from ETAS
The basic software for the FlexECU
contains, inter alia, modules for engine-speed capture and phase detection for CAM/CRANK signals, as
well as drivers for injection and ignition control. The synchronization
with the engine is easily accomplished
by virtue of the calibration of the
FlexECU’s engine position management (EPM) driver, during which the
parameters identifying the phase
orientation and properties of the rotary sensors for camshaft and crankshaft are entered. Once the synchronization has been achieved, the EPM
supplies, among other information,
the current engine speed and camshaft position. Based on this data, the
parameters for injection and ignition
calculated by the control software can
be applied with great accuracy by the
FlexECU basic software.
Function development
The software development is carried
out with ETAS ASCET. This includes
the creation of drivers for the interfaces between the FlexECU’s basic
software and control software developed in ASCET, and also the implementation of modules to control the
complement of sensors and actors.
The resulting modules are then used
to supply, by means of the interface
drivers, sensor values, such as pressures, temperatures, and pedal position. They also control and activate actuators, such as throttle valve, waste
gate, fuel pump, and intercooler.
The connection between the created
ASCET models and the basic FlexECU
software is accomplished by means
of software hooks inserted with the
aid of the ETAS EHOOKS tool. The
integrated software thus created is
subsequently written to the ECU by
means of ETAS INCA (Figure 3).
Among the functions being developed are the torque structure as
well as the air, fuel, ignition, and exhaust sub-systems. Within the torque
structure, a nominal torque value
is calculated based on the intention
Engine simulation model
MATLAB®/Simulink®
ASCET
INCA
INCA
LABCAROPERATOR
EHOOKS
LABCARAUTOMATION
Closed-Loop
Hardware-in-the-Loop
of the vehicle operator and current
engine operating point. The required
intake system pressure and ignition
angle efficiency are calculated on the
basis of the torque reserve. In the air
system, the intake system pressure is
regulated through the throttle valve
and waste gate positions. The respective current air flow provides the
data required by the fuel system for
calculating the required fuel volumes,
as well as the injection period − the
latter being modified with a correction value derived from the FlexECU’s
lambda interfaces, which can be configured for single or dual bank operation supporting up to three lambda
sensors per bank. The ignition system
uses engine speed and ignition angle
efficiency to calculate the required
ignition angle. The angle synchronous
activation of injectors and ignition
coils is managed by the FlexECU’s
basic software.
Hardware- and Software-in the-Loop
with LABCAR
LABCAR assists with downloading
the control signals of the FlexECU and
with adjusting the engine sensors.
Engine behavior resulting from actuator signals is simulated by means of
the Gasoline Engine Vehicle Model
(GEVM) from ETAS. The engine simulation provides for the calculation
of physical engine variables such as
speed, temperature, and intake pressure on the LABCAR-RTPC real-time
simulation target. The respective sensor voltages are emulated by LABCAR
and transferred to the FlexECU (Figure 2).
With the aid of the GEVM, the RTPC
uses the downloaded output values
of the FlexECU, such as ignition angle,
injection period, and throttle valve
angle, to calculate the air-fuel mass in
the combustion chamber. As long as
the resulting mixture remains within
the freely selectable ignition limits,
the values for torque, speed change,
and exhaust flow are calculated. Any
changes in engine speed directly impact both turbocharger system and
intake pressure, to which the FlexECU
responds in turn by adjusting the injection period and throttle valve
angle.
The HiL system permits the simulation
of limit ranges, such as very high engine speeds and temperatures that
would quite likely cause permanent
damage to an actual engine. In this
way, the safety-relevant functions,
e.g., speed and boost pressure limits,
are tested well ahead of their deployment on the real-world power plant.
Project outcomes
As a first result of the graduate theses, the interface drivers for the FlexECU’s basic software were developed
and added to the ASCET library.
These software interface components
are now available for future applications. Also, the sensor and actuator
system modules were programmed
and successfully tested by simulation
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on the LABCAR HiL system and on
the actual spark ignition engine.
Although the functional software
was designed to be as complex as
necessary, it was kept as simple, modular, and generic as possible. This not
only facilitates quick startups on the
test bench, but also ensures easy
transfer to other engine projects
in the future. Concurrent with the
function development, the GEVM
engine model was parameterized in
such a way that it is capable of intercepting faults that might result in
component damage. The automated
I/O test provides an option for fault
checking the entire hardware complement of the FlexECU within mere
minutes. The deployment of the
FlexECU and other ETAS tools in conjunction with the support from ETAS
have contributed to rapid success.
The results of this collaboration between Esslingen University and ETAS
will form the basis for additional
projects in the areas of function
development and calibration.
THE CHALLENGE
Universities and suppliers are not always capable of procuring or accessing world-class
production ECUs for the purpose of developing, testing, and deploying their own advanced
technological and proprietary control system for conducting realistic engine trials outside
a vehicle in a HiL or dyno environment, controlling a prototype hydraulic hybrid transmission
for mule vehicle evaluations, or for testing their own proprietary technological systems.
THE SOLUTION
The FlexECU is an open and economical ECU platform for the on-target system development of new control concepts. The FlexECU family of electronic control units is based
on production-ready versions of the current Bosch ECU hardware for either diesel or gasoline engine control. Due to rich I/O capabilities of both FlexECU variants, either have been
applied to a multitude of other non-engine control applications.
THE BENEFIT
In conjunction with the deployment of other members of the ETAS tool family, such as
ASCET, EHOOKS, INCA, and LABCAR, it was possible to make efficient work of starting
up the three-cylinder gasoline engine of a Smart on the test bench of the Esslingen
University of Applied Sciences. The project serves as the green light for future FlexECUbased function developments and calibrations at Esslingen University.