01Robotics - Programming Basics

8/9/2019 01Robotics - Programming Basics

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Programming Basics -RobotC

Introduction to Robotics


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Thinking aboutProgrammingCreating a successful robot takes a team effort

between humans and machines.

Role of the Robot

The robot follows the instructions

it is given, thereby carrying out the

plan.


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Human/Machine

Communication

Because humans and robots don’t normally speak the samelanguage, a special language must be used to translate the

necessary instructions from human to robot. These humantorobot languages are called programming languages. Instructionswritten in them are called programs. R!B!TC is "ust one ofmany such programming languages that humans use to talk tomachines.


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Think about “Behaviors”Behaviors are a convenient way to talk about what a robot is doing

and what it must do. #oving forward, stopping, turning, lookingfor an obstacle$ these are all behaviors.

Complex Behavior

%ome behaviors are big, like

&solve the ma'e.(

Basic or Simple Behavior

%ome behaviors are small, like &go

forward for ) seconds.( Big

behaviors are actually made up of

these smaller ones.


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Planning the Behaviors


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PSU!"C"!

*s the programmer becomes moree+perienced, the organi'ation of the

behaviors in nglish will start to

include important techni-ues from

the programming language itself,

like ifelse statements and loops.

This hybrid language, halfwaybetween nglish and the

programming language, is called

pseudocode.It is an important tool

in helping to keep larger programs

understandable.


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R"B"TC is te#t base$%Commands to the robot are first written as te+t on the

screen. They are then processed by the R!B!TCcompiler into a machine language file that the robot

can understand. inally, they are loaded onto the

robot, where they can be run.


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Co$eTe+t written as part of a program is called code. /ou

type code "ust like you type normal te+t. 0eep in mindthat capitali'ation is important to the computer.Replacing a lowercase letter with a capital letter 1or acapital letter with a lowercase letter2 will cause therobot to become confused.


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Co$e COLOR

*s you type, R!B!TC will try to help you out bycoloring the words it recogni'es. If a word appearsin a different color, it means R!B!TC recogni'es itas an important word in the programming language.


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Statements%tatements are instructions for the robot. The most

basic kind of statement in R!B!TC simply gives acommand to the robot. The motor[port3] = 127;statement in the sample program you downloaded isa simple statement that gives a command. It

instructs the motor plugged into #otor 3ort ) to turnon at full power.


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"r$er the Statements%tatements are run in order as -uickly as the robot is

able to reach them. Running this program on therobot turns the motor on, then waits for )444milliseconds 1) seconds2 with the motor still running,and then ends.


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RobotC RulesHow did ROBOTC know that motor[port3]= 127 and

wait1msec[3000] were two separate commands.5as it because they appeared on two differentlines6

7o. %paces and line breaks in R!B!TC are only used to separate words from

each other in multiword commands. %paces, tabs, and lines don’t affect the way

a program is interpreted by the machine.


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R"B"TC Rules

%o why *R they on separate lines6 or theprogrammer. 3rogramming languages are designedfor humans and machines to communicate. 8singspaces, tabs, and lines helps human programmers

read the code more easily. #aking good use ofspacing in your program is a very good habit for yourown sake.


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Punctuation%But what about R!B!TC6 9ow :I: it know where

one statement ended and the other began6 It knewbecause of the semicolon 1;2 at the end of each line.

very statement ends with a semicolon. It’s like the

period at the end of a sentence.


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Punctuation Pairs3unctuation pairs, like the parentheses and s-uare

brackets in these two statements, are used to markoff special areas of code. very punctuation pairconsists of an opening punctuation mark and aclosing punctuation mark. The punctuation pairdesignates the area between them as having special

meaning to the command that they are part of.


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Punctuation Pairs

:ifferent commands make use of different kinds of paired punctuation. The

motor command uses s-uare brackets and the wait1Msec command uses

parentheses. This is "ust the way the commands are set up. /ou will have to

remember to use the right punctuation with the right commands or plan.


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Control StructuresSimple statements do the work in ROBOTC, but

control structures do the thinking. Control structures1or control statements2 are pieces of code thatcontrol the flow of the program’s commands, ratherthan issue direct orders to the robot.

!ne important control structure is task main. very R!B!TC program includes

a special section called task main. This control structure determines which code

the robot will run as part of the main program.


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Control Structures


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CommentsComments are te+t that the program ignores. *

comment can contain notes, messages, andsymbols that may help a human, but would bemeaningless to the robot. R!B!TC simply skipsover them. Comments appear in green in R!B!TC.

01Robotics - Programming Basics

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