LSN1 Intro to Software Engineering

Transcription

1 LSN1 Intro to Software Engineering Department of Engineering Technology

2 LSN1 Software Engineering Process Requirements analysis Extracting the requirements of a desired software product Specification Decomposing the problem statement Precisely describing the software to be written Software architecture Algorithmic design Test solution Mathematically / logically verify design

3 LSN1 Software Engineering Process Code solution Language dependent Test and debug Unit and system level analysis Documentation Occurs throughout entire process Maintenance Extend functionality Fix bugs

4 LSN1 Software Engineering Process

5 LSN1 Development & Design The sooner you start to code, the longer the program will take - R. Carlson

6 LSN1 Problem Solving Problem Solving Steps Understand and isolate the problem Identify alternative solutions to the problem Select the best solution to the problem List the instructions that enable you to solve the problem using the selected solution Evaluate the solution Types of Solutions Heuristic solutions Algorithmic solution

7 LSN1 Define Problem Problem statement decomposition Inputs Processes Outputs Inputs Processes Outputs Performed second Performed last Performed first Do NOT try to define the processes without first defining the inputs and outputs

8 LSN1 Develop Solution Algorithms are the vital and necessary initial step in all software programming activities Algorithms are formed using top-down, stepwise refinement Formation of an algorithm Pseudocode: English-like phrases used to describe the algorithm Formula: Description of a mathematical equation Flowchart: Diagram showing the flow of instructions in an algorithm

9 LSN1 Develop Solution Test Algorithm Refinement (iterative process) Algorithm Components Sequential operations Caries out a single well defined task, finishes the task, and proceeds to the next task Conditional operations Ask a question then select the next operation to be executed based upon the answer to the question Iterative operations Repeat a set of instructions

10 LSN1 Flowchart Symbols Symbol Name Function Terminal Represents the beginning or end of a program. Flow lines Represent the flow of logic. Process Represents calculations or data manipulation. Input/output Represent inputs or outputs of data and information. Decision Represents a comparison, question, or other condition that determines alternate paths to be followed. Junction Represents joining of multiple pathways. Off-page connector Represents a break that is continued on another page.

11 LSN1 Flowchart Mobile robot example: Create an algorithm that moves a mobile robot in the following pattern using two drive motors (M1 and M2) Forward for 5 seconds at half speed Turns in a circle for 180 Forward for 5 seconds at half speed Stops M2 M1 5 1

12 LSN1 Coding and Debugging Code solution A more mechanical step Test & fix code Test data is often decided upon during analysis stage of algorithm development Test boundary and normal operating condition

13 LSN1 Program Documentation Requirements & specifications documentation Problem statement decomposition Design and analysis documentation IPO chart Algorithm (pseudo code / flowchart) Algorithm analysis Program code (with comments) Develop user operating material Programming Exercises Programming Projects

14 LSN1 Program Documentation Why documentation is important at all levels of development

15 LSN1 Program Maintenance Often the longest phase of development Include: Ongoing correction of newly discovered bugs Revisions to meet changing user needs Addition of new features

16 LSN1 Fischertechnik Robotic Kits Fischertechnik is a flexible construction system for designers Industrial robot kits for CIM modeling and training Mobile robot kits for modeling, research, and engineering education Controlled using PLCs or microcontroller

17 LSN1 Fischertechnik Mobile Robot Kit System for easily developing mobile robots Actuators 9VDC motors with built-in 50:1 gear reduction Lens tip lamp Buzzer Sensors Pushbutton Phototransistor (optical switch) Rotary encoders Controller 16-bit microcontroller Power supply NiMH 8.4V battery pack

18 LSN1 Robotic Sensors Tactile Pushbutton three-way switch Visual Phototransistor to read level of light or discrete states (light / dark) Distance Rotary encoders used to count angular distance

19 LSN1 Fischertechnik ROBOPro Software Graphical programming language that uses flowchart symbols Intuitive language for algorithmic development Provides easy access to mobile robot actuators and sensors Parameter inspection and setting Interfaces the ROBO-Interface module for downloading the program to the mobile robot

20 LSN1 Fischertechnik ROBOPro Software Flowchart Symbol Name ROBOPro Symbol Terminal Flow lines Process Input/output Decision Junction

21 LSN1 Fischertechnik ROBOPro IDE To create a new program select the New option from the File menu Location of programming symbols Program entered in Function tab Single-step in debugger Pause program in debugger Execute program in debugger Set download interface options Programming Symbols pallet Download program Stop program in on-line mode Start program in on-line mode

22 LSN1 Fischertechnik ROBOPro Software ROBOPro Software Example: Using previously created algorithm, create a ROBOPro program that moves the mobile robot in the following pattern Forward for 5 seconds at half speed Turns in a circle for 180 Forward for 5 seconds at half speed Stops M2 M1 5 1

23 LSN1 Fischertechnik ROBOPro Software Motor control setup M1 M2

24 LSN1 Fischertechnik ROBOPro Software Timer operation setup Connectivity Connecting lines can be changed by left-clicking on the line and moving it while holding the key down According to where the mouse is placed on the line, a corner or an edge of the line is moved Move a vertical line ( ) Move a horizontal line ( ) If the mouse is positioned over an oblique connection line, a new point is inserted into the connecting line when the left mouse button is selected ( ) If the mouse is positioned near an end point or a corner of a connecting line, this point can be moved while holding down the left mouse button ( )

25 LSN1 Fischertechnik ROBOPro Software Digital concepts Two possible state 1/0, ON/OFF, T/F, High/Low Two possible voltage values Pulse Single change in state Waveform Continuous signal with possible state changes

26 LSN1 Fischertechnik ROBOPro Software Pulse counting The rotary encoder provides four pulses for every revolution which can be used to turn a motor on for a precisely defined number of revolutions rather than for a given time Program flow input path State change to look for Number of pulses to count before proceeding Program flow output path Input interface to read DO NOT CHANGE Symbol modification parameters

27 LSN1 Fischertechnik ROBOPro Software Waiting for a logic state Waits until one of the digital inputs is in a particular state or until it changes in a particular way Program flow input path State or change to look for Program flow output path Input interface to read DO NOT CHANGE Symbol modification parameters

28 LSN1 Fischertechnik ROBOPro Software ROBOPro Software Example: Modify the previously created ROBOPro program to use the rotary encoders instead of time delays Forward for 40 pulses at half speed Turns in a circle for 180 Forward for 40 pulses at half speed Stops 3 I2 4 2 M2 M1 I1 5 M2 1 M1

29 LSN1 Fischertechnik ROBOPro Software Analog to Digital conversion Transfer of an analog sensor signal into a digital representation Resolution (n) The number of bits used to digitally approximate the analog value of the signal Digital State (N) The number of bit combinations that will represent the analog value N = 2 n

30 LSN1 Fischertechnik ROBOPro Software Phototransistors can convert an analog light level to a digital value The Fischertechnik Robo Interface uses a 10-bit A/D conversion Light values are represented by a discrete value between 0 to 1023 Analog inputs are connected through the AX and AY inputs on the Robo Interface

31 LSN1 Fischertechnik ROBOPro Software ROBOPro Software Example: Empirically determine the values read from the phototransistors connected to the analog inputs AX and AY for various colors when illuminated by a lamp output through output O5 White Black Red Green I2 AY O5 AX M2 M1 I1

32 LSN1 Homework Assignment ECT361 EX1.pdf Investigating algorithmic development and associated mobile robot programming using flowcharts References Software Engineering Association for Computing Machinery ( Portal ( Code of Ethics ( A/D Conversion