- Concept of V-Cycle for Controller Development
V-cycle for controller development has been applied to the software development
of automobile ECU (Electronic Control Unit) by worldwide automobile manufactures
and ECU suppliers. The V-cycle has its backbone on model based controller
development, and models constructed by MATLAB are applied to every development
process configuring V-cycle. The advantages of V-cycle model as compared
with traditional development cycle will be discussed in this tutorial.
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- Controller Design by MATLAB/Simulink/Stateflow
MATLAB has been regarded as defacto standard tool
among control engineers, and its toolboxes of Simulink and Stageflow also have
the big role to handle non-linear systems. A user designs a controller by
MATLAB environment, and he can validate the features of the controller by
off-line simulation on the platform where MATLAB tools work. The model
constructed by MATLAB is easy to know what are described, and the model can be
simulated in offline mode so as to know if the designed controller works
appropriately. These two factors allows MATLAB model to be regarded as
executable specifications. The model based controller development means that
all the development tasks are made based on the MATLAB models.
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- Rapid Controller Prototyping
The MATLAB
controller model should be validated by the real-time operation in conjunction
with actual plant like a robot and a vehicle, which allows a user to know if
the controller works properly in real world. Traditional development required
hand coding of the controller and its implementation on proprietary real-time
hardware, which needed a lot of effort and long period.
Rapid
prototyping tool like dSPACE system allows a developer to implement
Simulink/Stateflow model on the powerful general-purpose real-time hardware automatically
by integrating the control model with Simulink I/O blocks. Prototyping tool for
automobile onboard testing will be demonstrated to show how easily the control
model including triggered subsystem can be implemented on real-time hardware
and how easily the controller can be monitored.
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- Code Generation Equivalent to Hand-Code
The controller
model constructed by Simulink and Stateflow whose operation was validated by
rapid controller prototyping process should be manually programmed so as to be implemented
on target hardware of the controller previously. Some trials have been made to
generate C code from Simulink and Stateflow models automatically, but it has
been very difficult to create the code whose execution time and memory consumption
are equivalent hand-code.
TargetLink,
a code generator supplied by dSPACE is very exceptional code generator, which
allows a user to get the high efficient C code not only floating point but also
fixed point codes to be implemented on target controller hardware. The program generated
by TargetLink has been already implemented on commercial car controller in the
market, for example engine controller of Nissan Sentra 2000 model. TargetLink
will be demonstrated to show how efficient code is generated from
Simulink/Stateflow models.
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- Hardware-in-the-loop Simulation to Test Controller
Hardware-in-the-loop
(HIL) simulation is alternative approach of the testing by using actual plant
like airplanes and automobiles. This technology came from aerospace industry to
reduce the risk of the accidents due to bugs in the controller. Thanks to the
price reduction of HIL simulator systems, automobile industry has big demands
for the simulators, which allows them to reduce actual engine testing and
onboard vehicle testing, because they can reduce both test cost and risk of
test diver by HIL simulations.
Typical
applications of HIL simulation are engine simulator and vehicle dynamics simulator
for automobile industry, which require precise mathematical models running in
real-time. The simulator to test the controller for ESP (Electronics Stability
Program) will be demonstrated, and real-time animation software to show the
behavior of vehicle for example in the sudden braking condition on slippery
road will be also shown.
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- Final Controller Parameter Adjustment
The controller
parameters are necessary to be tuned so as to get comfortable operations for a
user before it is released to the market. This is the final process of V-cycle
development model, which required a lot of effort based on past experience.
However model-based development approach also is going to have big impact on
this time consuming process.
The
parameter tuning (calibration) engineer can get a lot of information from the
controller model in order to get the optimal point of a parameter efficiently.
In case a calibration engineer finds out any problem in this final process, he
can give the feedback to the controller designer by showing the problem in the
model, which allows them to recover the problem very efficiently. The new
concept of calibration process based on the model-based approach will be also
introduced.
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- Application Example of Visual Feedback System
Visual information
is recently highlighted as non-contact sensor, and some approaches are made to
build visual feedback system in the robotics field for example. Thanks to big
computation power of PC and enhancement image processing software, image has
been process at very high-speed, which allows a researcher to use the image
information as sensor signal of a controller. The stabilization of inverted pendulum
will be demonstrated as an application of visual feedback system.
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