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Cyberphysical
 System
 Topics
 in
 an
 Embedded
 Control
 Class
 at
 the
 University
 of
 Michigan
 
Embedded Control Systems
•  Background:
–  University of Michigan and Ford Motor Company, 1998 (Dr. Ken Butts) –  Control engineers and computer engineers: Why can’t they talk to each other?

J. S. Freudenberg and J. A. Cook, EECS Dept., University of Michigan, Ann Arbor MI 48109 jfr@umich.edu jeffcook@umich.edu
  Embedded Control Lab: UM and ETH Lectures (I)
•  •  •  •  •  •  •  •  •  Quantization Sampling Linear filtering Quadrature decoding DC motors Pulse Width Modulation (PWM) amplifiers Motor control: current (torque) vs. speed MPC5553 architecture. Peripherals: eTPUs, eMIOS, eDMA,… Haptic interfaces.
–  virtual wall –  virtual spring/mass/damper
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UM Project: Adaptive Cruise Control

•  Driving simulator •  Bicycle model of vehicle •  6 vehicles interacting over CAN network •  Lane centering •  ACC algorithm: 3 states
–  manual (sliding pot) –  constant speed –  constant distance
f() Trigger
enable Desired Speed ring angle) radians ual_torque (throttle) (s,n,psi,us)1..5 enable Force desired speed steering angle throttle delta (s,n,psi,us)1..5 s,n,psi,us u Steering Actuator Torque

•  Characteristics:
–  Interface with external environment –  Real time critical –  Hybrid behavior –  Distributed, networked control

Force Steering Torque

Steering Torque

delta

s,n,psi,us

s,n,psi,us(s,n,psi,us)1...6

1 (s,n,psi,us)1...6

C_INPUTS

Steering Actuator Torque u

(s,n,psi,us)1..5

!

Cyber-Physical Systems

1

•  Simulink/Stateflow modeling of hybrid dynamical systems •  Numerical integration.

C_ACC

P_CAR

C_OUTPUTS

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10

Outcome: Two Courses
•  UofMichigan: EECS 461, Embedded Control Systems
–  11 years as regular course –  150+ students/year –  Student body: •  EE and CE seniors and some grads •  occasional grads from Mechanical, Civil, Aerospace, Biomedical, Naval Architecture and Marine Engineering

Haptic Interface
behavior sensor (taction and kinesthesia) position velocity force sensor (encoder)

Lectures (II)
•  Networking:
–  Control Area Network (CAN) protocol. –  Bus utilization

Controller Block Diagram

Human

actuators (muscles)

Haptic Device CPU
algorithm (virtual environment)

force actuator (DC motor)

•  Interrupt routines: timing and shared data •  Software architecture
–  –  –  –  Round robin Round robin with interrupts Real time operating systems (RTOS) Multitasking

•  ETH Zurich: Embedded Control Systems
–  five years as an intensive two week block course –  33 students/year –  Student body: •  Mechanical Engineering Graduate Students
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!

Cyber-Physical-Physiological System
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•  •  •  •  • 

Shared data: semaphores, priority inheritance, priority ceiling Real time computation. Rate monotonic scheduling. Rapid prototyping. Autocode generation. Model based embedded control software development PID control design
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Industry Trends
Harvard Business Review, 2010:

Laboratory Overview
•  MPC5553 Microcontroller (Freescale)
–  Originally automotive control, now used in many applications

Laboratory Exercises
•  Each lab exercise teaches
–  a peripheral on the MPC5553 –  a signals and systems concept –  uses concepts (and code!) from the previous labs –  Labs 1-7: program in C –  Lab 8: autocode generation
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•  Development Environment
–  Debugger (P&E Micro) –  Codewarrior C compiler (Freescale)

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•  Haptic Interface
–  Force feedback system for human/computer interaction

•  Rapid Prototyping Tools
2005 2009 2010

“GM's biggest engineering recruiting challenges are software and controls engineering”
Detroit Free Press, October 2012
3

–  Matlab/Simulink/Stateflow, Real Time Workshop (The Mathworks) –  RAppID Toolbox (Freescale)

•  Real Time Operating System
–  OSEKturbo RTOS (Freescale)
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•  •  •  •  •  •  •  • 

Lab 1: Familiarization and digital I/O Lab 2: Quadrature decoding using the eTPU Lab 3: Queued A-D conversion Lab 4: Pulse Width Modulation and virtual worlds without time Lab 5: Interrupt timing and frequency analysis of PWM signals Lab 6: Virtual worlds with time. Lab 7: Controller Area Network (CAN) Lab 8: Rapid Prototyping
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