> Power Supervison Desired Output level Source Diesel Valve Sink Diesel Valve > Valve Regulator Sink T = 40 ms Air Valve CBSE Course The SaveComp Component Technology

Vehicular Systems Software Charateristics – Safety – Reliability – Resource efficiency – Predictability Engineering Activities – Targeting non general System Architecture – Early Analysis – Modelling – Verification 06/12/2015Mikael Åkerholm, CBSE Course 20052

Example: The architecture of a car control system Page 3, 6 December 2015 Vehicle mechanics ECU Sensor ActuatorSensor ECU Sensor ActuatorSensor ECU Sensor Actuator Sensor gateway (CAN) BUS brakeinjection Infotaiment ECU – Electronic Control Unit

The architectural design challenge Page 4, 6 December 2015 Vehicle stabilitySuspensionDrive by wire…… Complex functions Local Control Functions Sensor ActuatorSensor Basic functions Local Control Functions Sensor ActuatorSensor How to implement complex functions based on local control functions?

Problem: resource sharing Page 5, 6 December 2015 Sensor 1 Sensor 2 Sensor 3 Sensor.. Network resources Sensor.. Execution resources Node 1 Node 2 Node 3 Node … Actuator 1 Actuator 2 Actuator 3 Actuator … Can functions of different criticality be allowed to share resources?

Challenge – open and dependable platform Page 6, 6 December 2015 sensors Vehicle actuators Engine ControlLocal brake ControlTransmission……… local Vehicle stability Cruise control AntispinGlobal (complex) functions Hardware Input/output drivers Middleware ECU Applications SOFTWARE COMPONENTS Collision detection

Challenge – open and dependable platform Page 7, 6 December 2015 Hardware Input/output drivers Middleware ECU Applications C1C2 Requirements Separation of hw from SW development Separation of SW component development

Example: A task as a component Component-model used in REBUS (Volvo construction equipment) The timing requirements are specified by release- time, deadline, WCET and period December 6, 2015 Ivica Crnkovic (c) : Component-based real-time systems

Real time attributes 06/12/2015Mikael Åkerholm, CBSE Course What is Task Period Deadline WCET Precedance

Challenges when constructing RT systems Most of the real-time systems are based on following: 1.Several parallel activities are given some unique priorities 2.A resource manager makes sure the task with the highest priority will execute December 6, 2015 Ivica Crnkovic (c) : Component-based real-time systems 13 Activities Resource manager timeCPU ready

Definition – task Task A sequential program performing an activity and that possibly communicates with other tasks in the system. A task often has a priority relative to other tasks in the system. Sometimes thread is used instead of task. Process A virtual processor that can handle several tasks with a common memory space. December 6, 2015 Ivica Crnkovic (c) : Component-based real-time systems

Periodic tasks An infinite sequence of identical activities – invocations (jobs) December 6, 2015 Ivica Crnkovic (c) : Component-based real-time systems time Task A A1A1 (Inv. 1) A2A2 (Inv. 2) A3A3 (Inv. 3) period Analogy from real life: Example: Audio and video sampling Regulating Monitoring of temperature and pressure Execution time

What is a release time and deadline? December 6, 2015 Ivica Crnkovic (c) : Component-based real-time systems Task release time is the earliest point in time we can activate (release) the task Airbag-example: Crash Too late time Too early Release time Deadline

Relations between components and tasks Components – design Units Tasks – execution Units Mapping: – Simplest: a Component is a task – Complex A set of components makes a task A component can be split into several tasks 06/12/2015Mikael Åkerholm, CBSE Course

Composition of Components December 6, 2015 Ivica Crnkovic (c) : Component-based real-time systems

What is with time attributes? How do we specify properties of an assembly? – Execution time (WCET,…) How do we map assembly properties to the components being composed? – Period? – Priority? December 6, 2015 Ivica Crnkovic (c) : Component-based real-time systems

Properties of Composed components Can we use WCET? – No – WCET cannot be computed since its parts may be executing with different periods. End-to-end deadlines – Are set such that the system requirements are fulfilled – Should be specified for the input to and output from the component Latency – time for an assembly to respond to input signal – Average, Worst case (end-to-end deadline), best case December 6, 2015 Ivica Crnkovic (c) : Component-based real-time systems

EXAMPLE SAVECOMP COMPONENT MODEL SaveCCM 06/12/2015Mikael Åkerholm, CBSE Course

SaveComp Overview 06/12/2015Mikael Åkerholm, CBSE Course

SaveCCM Component Model Tradeoff: – Freedom vs. Restrictions SaveCCM restrictive, but expressive power focused on domain specific needs, e.g., – Mode Changes – Static Configuration – Control Feedback 06/12/2015Mikael Åkerholm, CBSE Course

Architectural Elements Components – In and Output ports, (1) data only, (2) triggering, (3) triggering and data (for all elements, not only components) – Basic units of encapsulated behavior – Execution model: read input, execute, write output 06/12/2015Mikael Åkerholm, CBSE Course > name Input port, data Input port, triggering Input port, data and triggering Output port, data Output port, triggering Output port, triggering and data

Architectural Elements Switches, special type of component Conditionally changes the component interconnection structure – Static or dynamic configuration of conditions 06/12/2015Mikael Åkerholm, CBSE Course > name PID INP INI IND OUTP OUTI OUTD Switch name { Inports: INP:Pport, INI:Iport, IND:Dport, P:Setport, I:Setport, D:Setport; Outports: OUTP:Pport, OUTI:Iport, OUTD:Dport; Switching: P: INP->OUTP; I: INI->OUTI; D: IND->OUTD; }

Architectural Elements Assemblies, special type of component Consists of components and switches Naming of sub-systems, hiding internal structure 06/12/2015Mikael Åkerholm, CBSE Course

Compile-Time Overview 06/12/2015Mikael Åkerholm, CBSE Course Design- Time Component model Real-Time Analysis Real-time model Synthesis Compile- Time Model transformation Run- Time Target application RTOS t Task Allocation Attribute Assignment Analysis Glue Code Generation Target Compiler Component model RTOS Fully Automated Compile-Time Step

Run-Time System Applications have no dependencies to operating systems, all operating system dependencies are automatically generated glue code, gives portable and reusable components Prototype: – Win32 for Simulation with the CCSimTech simulation technique – RTXC RTOS for target 06/12/2015Mikael Åkerholm, CBSE Course

06/12/2015Mikael Åkerholm, CBSE Course Road Signs Enabled Current Speed Road Sign Speed ACC Max Speed Distance ACC Enabled Brake Pedal Used > 50 Hz 10 Hz Brake Signal Throttle Brake Assist > Logger HMI Outputs > Object Recognition > Mode Switch > ACC Controller > Brake Assist ACC Max Speed ACC Application Speed Limit >