A Brief Introduction to Functional Safety

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1 Who Am I? Name: Profession: Department: Field of Work: Background: Research: Uwe Creutzburg Professor at University of Applied Sciences, Stralsund, Germany Electrical Engineering and Computer Science Embedded Systems and Microprocessor Technology > 10 Years of employment in the automotive industry at AUDI, Continental, Volkswagen Research & Development for EPS, ABS, Infotainment, HW/SW, Tools & Processes Electric Power Steering (Volkswagen) Elche 1-1 Agenda Part I Part II A Brief Introduction to Functional Safety Elche 1-2 1

2 Agenda A Short Story About Model-Based Design Part I: Model Based Design Model Based Design currently is the most popular method used in the automotive industry for the development of new functionality in chassis and power-train applications. The idea is to use state-of-the-art techniques in order to - speed-up the development process of complex systems - enhance the quality of work products - and to safe money! Elche 1-3 Example: Magnetic Ball (or Levitation) F G Iron Core Coil Hollow Sphere Elche 1-4 2

3 Actuator - Active F M F G Iron Core Coil Current Hollow Sphere Elche 1-5 Magnetic Ball Physical Modeling Elche 1-6 3

4 Model Based Design Plant Model Elche 1-7 Model Based Design Plant Model Force Electromagnetic Force 1 0,1 0,01 0,05 0,15 0,25 0,35 0,45 Distance Elche 1-8 4

5 Sensor Basic Idea Plexiglass Tube LC-Oscillator: f 0 ~ 10kHz Elche 1-9 Sensor Ball is up Plexiglass Tube rel. Voltage µc Timer Output Matched Resistor R LC-Oscillator Voltage 1,0 0,8 0,5 0,3 0,0-0,3-0,5-0,8-1, Time/µs Elche

6 Sensor Ball is down rel. Voltage R LC-Oscillator Voltage 1,0 0,8 0,5 0,3 0,0-0,3-0,5-0,8-1, Time/µs Elche 1-11 Sensor - Lock-In Amplifier (analog equivalent) Elche

7 Actuator Power Electronics F M F G Elche 1-13 Agenda Discussion - What is the advantage of using a Lock-In-Amplifier - Why is it necessary to use a Reverse-Diode? - My approach is to measure the amplitude of the sinus. What else could be feasible? - Is the sensor linear with respect to the height? Elche

8 Model Based Design Closed Loop Input IF Controller IF Sensor Plant Elche 1-15 Model Based Design Plant Model (TMW) Elche

9 Model Based Design Plant Model (Derived) Magnetic Ball Boundaries Not brilliant, I know! Elche 1-17 Model Based Design Plant Model Force Electromagnetic Force 1 0,1 0,01 0,05 0,15 0,25 0,35 0,45 Distance Elche

10 Model Based Design Rapid Control Prototyping Sensor Interface Power Electronics Elche 1-19 Model Based Design Rapid Control Prototyping EMagnet_Power_GND EMagnet_Power_Plus -15V_out Analog_GND +15V_out PWM_GND PWM_Sig LIA_out EMagnet_Current LC_out LC_GND Supply_Neg Supply_GND Supply_Pos Elche

11 Model Based Design Development of Controller Elche 1-21 Model Based Design Online Adjustment of Controller Elche

12 Model Based Design Success!! Elche 1-23 Agenda Discussion - Everything is non-linear in this setup. Why can we use a simple PID-Controller that normally requires a linear plant? - How to find the Parameters for the PID-Controller? Elche

13 Program Sequence Chart Config Control ISR POR Init - Clock - ADC - Timer - IO - Interrupt X Sleep Mode Application - Get ADC - Call Controller - Set PWM X Sleep Mode Timer Event Restore State of µc Elche 1-25 Program Sequence Chart Config Control ISR POR Init - Clock - ADC - Timer - IO - Interrupt X Sleep Mode Application - Get ADC - Call Controller - Set PWM X Sleep Mode Timer Event Restore State of µc Elche

14 Model Based Design Code-Generation with TargetLink Elche 1-27 Model Based Design Code-Generation with TargetLink Elche

15 Sensor Lock-In Amplifier Equivalent rel. Voltage Synchronous Sampling! LC-Oscillator Voltage 1,0 0,8 0,5 0,3 0,0-0,3-0,5-0,8-1, Time/µs Elche 1-29 Sensor Generated Code Excerpt I (Interface) struct tag_alev alev = { 0 /* Reference: LSB: 2^0 OFF: 0 MIN/MAX: */, 0 /* Sensor: LSB: 2^0 OFF: 0 MIN/MAX: */, 0 /* Output: LSB: 2^0 OFF: 0 MIN/MAX: */, 1 /* */ /* Ki: LSB: 2^-12 OFF: 0 MIN/MAX: */, 51 /* 0.8 */ /* Kp: LSB: 2^-6 OFF: 0 MIN/MAX: */, 40 /* 10. */ /* Kd: LSB: 2^-2 OFF: 0 MIN/MAX: */, 2 /* 0.5 */ /* Ad: LSB: 2^-2 OFF: 0 MIN/MAX: */ }; Elche

16 Sensor Generated Code Excerpt I Void Controller(Void) { static Int16 X_SLEV1_xd = 0 /* LSB: 2^-2 OFF: 0 MIN/MAX: */; static Int16 X_SLEV1_xi = 0 /* LSB: 2^-7 OFF: 0 MIN/MAX: */; /* Sum: Controller/e */ SLEV1_e = (Int16) (((Int16) (((UInt16) alev.reference) - ((UInt16) alev.sensor))) << 6); /* Gain: Controller/Ki */ SLEV1_Ki = (Int16) ((((Int32) SLEV1_e) * ((Int32) alev.ki)) >> 11); /* Sum: Controller/s_i */ SLEV1_s_i = SLEV1_Ki + X_SLEV1_xi; if ((SLEV1_Ki >= 0) && (X_SLEV1_xi >= 0) && (SLEV1_s_i < 0)) { SLEV1_s_i = 32767; } else { if ((SLEV1_Ki < 0) && (X_SLEV1_xi < 0) && (SLEV1_s_i >= 0)) { SLEV1_s_i = ; } } *** Elche 1-31 Sensor Generated Code Excerpt II Void Controller(Void) { *** /* Gain: Controller/Kd */ Aux_S32 = ((Int32) SLEV1_e) * ((Int32) alev.kd); SLEV1_Kd = C I16SHRI32C6_LT16_SATb(Aux_S32, 6, , ); /* Sum: Controller/s_D */ SLEV1_s_D = (Int16) (((UInt16) X_SLEV1_xd) + ((UInt16) SLEV1_Kd)); /* Gain: Controller/Kp */ Aux_S32 = ((Int32) SLEV1_e) * ((Int32) alev.kp); /* Sum: Controller/s_PID # combined # Sum: Controller/s_PI */ SLEV1_s_PID = (Int16) (((Int16) (((Int16) (X_SLEV1_xi >> 7)) + ((Int16) (C I16SHRI32C6_LT16_SATb(Aux_S32, 6, , ) >> 6)))) + ((Int16) (SLEV1_s_D >> 2))); } /* TargetLink outport: Controller/output # combined # Saturation: Controller/sat_Out */ alev.output = C I16SATI16_SATb(SLEV1_s_PID, 511 /* 511. */, 0 /* 0. */); /* Unit delay: Controller/xi X_SLEV1_xi = SLEV1_s_i; /* Unit delay: Controller/xd X_SLEV1_xd = (Int16) (((UInt16) (Int16) ((((Int32) SLEV1_s_D) * ((Int32) alev.ad)) >> 2)) - ((UInt16) SLEV1_Kd)); Elche

17 Model Based Design Target-Board Actuator Sensor Elche 1-33 Agenda Discussion - The Model didn t make use of PWM signals. Why is that not necessary in this example? - What is the difference between floating-point and fixed-point implementation? - Why not using floating-point data types on the final target MSP430F2012? Elche