Modul. Integration. & Test. System. Integration. & Test. Late system level response. â The later failures ... Traffic engineering programs like LISA+ facilitate an planning process. .... East-west road linear increases. Analysis: Constant green ...
LCCC Workshop System Design meets Equation-based Languages Functional Development with Modelica Dr. Stefan-Alexander Schneider Dr. Stefan-Alexander Schneider
21. September 2012
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The Winchester House Neither Architecture nor Plan
Winchester House (construction 1884-1922) 160 rooms over 7 floors Neither Architecture nor Plan see http://www.winchestermysteryhouse.com/ Dr. Stefan-Alexander Schneider
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Systems Engineering
As Is
To Be
Problem
Early system level response
Late system level response Requirements
System Integration & Test
System Design Modul Design Component Design
Modul Integration & Test
How to achieve an earlier system level response?
System Design Modul Design Component Design
Component Test
The later failures are found, the more expensive they are!
Requirements
Solution
System Integration & Test Modul Integration & Test Component Test
Early evaluation of system reduces the risk of missing the „best solution“!
Virtual System Prototyping
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The Vee-Model of the Systems Engineering Short Feedback Loops by Virtual Integration
Time
Solution
modeling
System
Hand-over and Usage System Integration & Test
System Design
Component
Design
Modul
Module Design
Module Implementation
Module Integration & Test
Component Test
Integration
System
System Level Requirements
Modul
simulation
Component
Task
conventional way
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Dr. Stefan-Alexander Schneider
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Traffic Flow Optimization with a Traffic Light
Traffic Planning includes among others • Traffic Flow Optimization and • Avoiding Traffic jams Dr. Stefan-Alexander Schneider
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Traffic Lights serve to control the traffic and arrange for traffic participants a behavior
Typical Sequence of coloured lights: Red Light prohibits any traffic from proceeding, Red and Yellow Light prepare to cross, Green Light allows traffic to proceed in the direction denoted, and Yellow Light denotes, if safe to do so, stop.
circulation time (t_Clock) denotes the sum of all traffic lights phases Dr. Stefan-Alexander Schneider
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Plan of Signal Times Presentation similar to GANTT-Charts Traffic engineering programs like LISA+ facilitate an planning process.
Dr. Stefan-Alexander Schneider
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Task Restriction to a simple crossing of 4 lanes and traffic lights:
How looks like a workflow to development an embedded system, here the control system of the traffic lights, using the design environment Modelica? Dr. Stefan-Alexander Schneider
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System Level Requirements
Task
Solution
System Level Requirements
Hand-over and Usage System Integration & Test
System Design
Module Design
Module Implementation
Dr. Stefan-Alexander Schneider
Module Integration & Test
Component Test
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Requirements to system road intersection
1. Sum of all waiting times should be minimized. 2. Both directions should periodically served with the minimum green signal time t_Min.
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Functional Safety: Desired Behavior for System Failure Emergency control mode: Traffic lights from the major roads turn off and the traffic lights from the side streets blink yellow. This indicates that the proper operation of the traffic lights is not guaranteed and supports on the other hand the given traffic signs. Secure on the electrical level: If a light source is out of order, so none of the directions may be given the green signal and it should, if possible, the red signal shown.
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System Design
Task
Solution
System Level Requirements
Hand-over and Usage
Module Design
Module Implementation
Dr. Stefan-Alexander Schneider
Module Integration & Test
Component Test
Integration
System Integration & Test
System Design
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Design of the System System Traffic Lights: Plant-Controller with to be defined interfaces for the components of plant and controller.
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Description of System Component Plant: Crossing of two lanes. Component Controller : Calculates from given numbers of traffic members using an explicit computation rule for the duration of the green phase. Description of Interfaces: Interface between plant and controller is given by six real values: four numbers of vehicles in the waiting queues n_North, n_East, n_South, and n_West and the two green phase values t_NorthSouth and t_EastWest.
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Implementation of the System
t_Clock
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Module Design
Task
Solution
System Level Requirements
Hand-over and Usage
Module Design
Module Implementation
Dr. Stefan-Alexander Schneider
Module Integration & Test
Component Test
Integration
System Integration & Test
System Design
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Design of the Plant
Simple Growth Model for all four queues:
n North, East,South,West
c c _ Out , nNorth, East,South,West 0 c
Green Phase Values:
tMin t NorthSouth, EastWest tClock
Growth Constant: c Decay Constant: c_Out
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Design of Controller Controller maps from IR4 to IR2: infinite number of implementations!
We are in the Zugzwang!
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First Strategy to Design the Controller
Simple Strategy: Initialize both direction with red Default-Controller: distribute the available time (circulation time (t_Clock)) equally to both green phases
t NorthSouth, EastWest tClock / 2
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Module Implementation
Task
Solution
System Level Requirements
Hand-over and Usage System Integration & Test
System Design
Module Design
Module Implementation
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Module Integration & Test
Module Test
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Implementation First Controller Strategy
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Interaction with Sensors and Actors Initialize Plant; while (true) {
transfer values of vehicles to Controller; calculate length of green phases; simulate traffic lights; update vehicle values;
// interface // update Controller // interface // update Plant
}
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Module Integration and Test
Task
Solution
System Level Requirements
Hand-over and Usage System Integration & Test
System Design
Module Design
Module Implementation
Dr. Stefan-Alexander Schneider
Module Integration & Test
Module Test
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First Use Case
Both roads north-south and east-west are equally frequented. Parameters: c_EastWest = 1 [1/s] c_NorthSouth = 1 [1/s] c_Out = 2.2 [1/s]
n_North = n_South = 100 [1] n_East = n_West = 50 [1] t_Min = 10 [s] t_Clock = 150 [s] Dr. Stefan-Alexander Schneider
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Results of Model-in-the-Loop
Both roads north-south and east-west are equally frequented. Parameters: c_EastWest = 1 [1/s] c_NorthSouth = 1 [1/s] c_Out = 2.2 [1/s]
n_North = n_South = 100 [1] n_East = n_West = 50 [1] t_Min = 10 [s] t_Clock = 150 [s] Dr. Stefan-Alexander Schneider
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Conclusion of first Use Case
The symmetric control strategy works as expected. We study a further use case to test our implementation.
Modelica 3D Animation, Special Thanks to Christoph Höger, TU Berlin
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Second Use Case North-south road less traveled and east-west road however strong. Parameters: c_EastWest = 2 [1/s] c_NorthSouth = 0.2 [1/s] c_Out = 2.2 [1/s] n_North = n_South = 100 [1] n_East = n_West = 50 [1] t_Min = 10 [s] t_Clock = 150 [s]
Dr. Stefan-Alexander Schneider
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Results of Second Use Case North-south road less traveled and east-west road however strong. Parameters: c_EastWest = 2 [1/s] c_NorthSouth = 0.2 [1/s] c_Out = 2.2 [1/s] n_North = n_South = 100 [1] n_East = n_West = 50 [1] t_Min = 10 [s] t_Clock = 150 [s]
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Analysis of second Use Case Observation: North-south road drops to 0 and remains constant, where as East-west road linear increases Analysis: Constant green phase ratio reflected by 1 to 1 (north-south to east-west) obviously does not reflect the asymmetric vehicle ratio of 1 to 10 good enough
Conclusion: This undesirable behavior motivates another requirement for our controller.
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System Level Requirements Additional Requirement
Task
Solution
System Level Requirements
Hand-over and Usage System Integration & Test
System Design
Module Design
Module Implementation
Dr. Stefan-Alexander Schneider
Module Integration & Test
Component Test
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Additional Requirement to Controller Introduction of two key indicators:
Ratio of queues
k1 : nNorth nSouth / nEast nWest
Ratio of green phase
k2 : t NorthSouth/ t EastWest
"The longer the green phases, the more vehicles can pass.“ In the sense of the customers of the intersection, we additionally require:
k1 k2
Dr. Stefan-Alexander Schneider
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Alternative Implementation of the Controller Alternative controller with:
This implementation has the following desirable properties:
= 0 reflects no traffic in east-west direction and consequently minimum green time for east-west = 1 correspondingly for the other direction Dr. Stefan-Alexander Schneider
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Implementation of alternative Controller
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Results of Model-in-the-Loop of second Use Case
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Results of Model-in-the-Loop of second Use Case
The temporal evolution of the vehicle values in the first application with alternative controllers. Also the first application can be controlled by the alternate controller. Although he produced, in contrast to the first controller has a vibration, but remain limited to vehicle values.
Dr. Stefan-Alexander Schneider
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Results of Model-in-the-Loop of second Use Case
The temporal evolution of the vehicle values in the first application with alternative controllers. Also the first use case can be controlled by the alternate controller. Although it produces, in contrast to the first controller, a small oscillation, but remain limited to vehicle values. Dr. Stefan-Alexander Schneider
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System Integration and Test
Task
Solution
System Level Requirements
Hand-over and Usage System Integration & Test
System Design
Module Design
Module Implementation
Dr. Stefan-Alexander Schneider
Module Integration & Test
Module Test
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Implementation of Traffic Lights by Light Emitting Diodes (LEDs)
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Driving the actuators
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Development in C for µController
MPLAB Version 8.84 from Microchip Technology Inc. Dr. Stefan-Alexander Schneider
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PIC32 Starter Kit
µController with 80 MHz, 512KB Flash, 32KB RAM, USB Dr. Stefan-Alexander Schneider
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Target Code Generation
Python-Script Dymola2C.py
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Processor-in-the-Loop Simulation
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Results of Processor-in-the-Loop of second Use Case
red light
ready to operate
yellow light
Debug mode
Dr. Stefan-Alexander Schneider
green light
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Advantages of Virtual Integration Common Technical Basis concept
design
implementation
Check Yes / No
virtual integration
classic
#include if (result_b > result_d) var_i = 0.7 * result_ else
check
Dr. Stefan-Alexander Schneider
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System Integration and Test
Task
Solution
System Level Requirements
Hand-over and Usage System Integration & Test
System Design
Module Design
Module Implementation
Dr. Stefan-Alexander Schneider
Module Integration & Test
Module Test
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Development of Traffic Lights
Dr. Stefan-Alexander Schneider
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Architecture of the Library SafeDiscreteControl Concept for: Basic Blocks, Composite Blocks, Clocks, Clock Blocks, Atomic blocks, … Support for Datatypes: UInt4, Sint4, UInt8, SInt8, UInt16, SInt16, UInt32, SInt32, Float, Double, Boolean, Char8, Char16, …
Equations v = expr; or, but not – sin(u) + y = 0; Arithmetic Operations: +, -, *, /, gain, …
Numerical Support functions: abs, sign, min, max, sin, cos, tan, log, exp, … Concept for review, traceability, …
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Acknowledgments, Literatur, and Links Acknowledgments Bernhard Thiele, DLR, Synchronos conform modeling, defining the subset Christoph Höger, TU Berlin, Modelicca3d Animations Tobias Hofmann, TU München
Literatur & Links • • • •
Brunner, Ritz; Traffic Light Flower; http://www.brunner-ritz.de/bau.html; 2002 Wikipedia. LISA+ Wikipedia, Die freie Enzyklopädie, 2011. [Online; 28. März 2012]. Huckle, Schneider; Numerische Methoden; Springer; 2005 Bonvinia, Donidab, Leva; Modelica as a design tool for hardware-in-the-loop simulation; 7th Modelica Conference; 2009
Any questions, any hints?
Dr. Stefan-Alexander Schneider
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Development of Traffic Lights Dr. Stefan-Alexander Schneider
Thank you for your attention!
Dr. Stefan-Alexander Schneider
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The End.
Dr. Stefan-Alexander Schneider
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Aufgedeckte Abweichungen am Beispiel numerischer Aspekte der funktionalen Sicherheit ShiftOperationen Inkorrekte Optimierung durch Einsatz von Fused Multiply-Add/Subtract Opcodes (madd.f/msub.f)
Unäres Minus für Uint
Compilerfehler beim Vergleich von +0 und -0 Integrationsverfahren für embedded Systeme Float vs. Fix-Point Übersicht aktuelle Doktorabreiten
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Unexpected Behaviour in SHIFT-Operations Fehlerbeschreibung: The shift operator e.g. on Uint16 has unexpected behaviour. If a value is shifted by more than 16, than the result is not allways 0, e.g.
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