Advanced Cyber-Physical Systems Notes

1 Introduction

• Definition of Cyber-Physical Systems (CPS):

  • A CPS is a computer system where mechanisms are controlled or monitored by computer-based algorithms, intertwining physical and software components.

  • Operate on different spatial and temporal scales, and can interact based on context.

  • Examples include autonomous vehicles, medical monitoring systems, and industrial control systems.

• Relation to Embedded Systems and IoT:

  • CPS shares similarities with Internet of Things (IoT), with a broader integration of physical and computational elements.

• Challenges in Development:

  • Integration of various engineering disciplines (electrical, mechanical, software).

  • Lack of a common design language across disciplines.

1.1 More about CPS

• Levels of Functionality:

  • CPS can be categorized into five levels, which illustrate its operational capabilities and complexities within manufacturing contexts.

2 Discrete and Hybrid Automata

• Discusses models for control engineering tasks in CPS, emphasizing the interconnectedness of components.

2.1 Discrete Automata

Definition and Technical Realization

• A Deterministic Finite Automaton (DFA) is represented by a 5-tuple:

  • M = (Z, Σ, δ, z0, E)

  • Z: Set of states, Σ: Finite input alphabet, z0: Starting state, E: Final states, δ: Transfer function.

• Implementation:

  • States are realized through memory allocations in registers (binary values).

Forms of Representation

• State Graphs:

  • Nodes represent states, and edges represent transitions with conditions.

  • Named states and input/output specifications are used.

• Switching Tables (FSM Table):

  • Lists next states and output signals based on the current state and inputs.

2.1.3 Synthesis of Simple FSM

1. Signal determination and diagram sketching.

2. State diagram creation (structure and design of the task).

3. Derailleur/alphabet configuration table setup.

4. State minimization for design simplicity.

5. State coding using binary form.

6. Calculate subsequent and output networks.

7. Realization and testing of the FSM.

2.2 Introduction to Hybrid Automata

• Hybrid systems combine continuous and discrete dynamics, useful for applications such as modeling real-world phenomena (e.g., bouncing ball).

• Formalized as Hybrid Automata, which employ variable behaviors defined by differential equations and control modes.

3 Data Types and Data Representation

3.1 Polyadic Number Systems

• Describes how different bases (binary, octal, decimal, hexadecimal) represent numbers.

• Conversion between systems: Can be performed through calculating decimal equivalents followed by integer division to switch base systems.

3.2 Representation in Computers

Characters

• Represented using character sets (e.g. ASCII, Unicode) for encoding text data.

Fixed-Point Numbers

• Represent whole numbers distinctly based on bit positions.

Floating-Point Numbers

• IEEE-754 format for representing rational numbers with a dynamic range, accommodating normalization and exceptions.

4 A Short Introduction to Microcontroller

4.1 Von-Neumann-Model

• A computer consists of CPU, memory, and I/O unit, following the stored-program concept where data and instructions are handled in memory.

4.2 Sequential Command Execution

• Commands are executed in a two-phase process: fetching (reading instruction from memory) followed by execution (action based on previously fetched data).

5 Interfacing

5.1 Introduction and Subdivision

• Peripheral devices interface between microcontrollers and external environments, differing from memory handling.

5.3 Serial I/O Systems: RS232 and RS422

• Description of early connection development and standardization of serial interfaces (RS232), including physical definitions and communication protocols.

6 Advanced Topic: Cyber Security

• Highlights the impact of cyber security on CPS functionality. Misbehaviors in controlling devices can lead to catastrophic failures, necessitating high standards for functional safety and security.