1chung robofest 2007 introduction to robolab workshop feb. 3, 2007 maurice tedder
TRANSCRIPT
1chung
Robofest 2007 Introduction to RoboLab
Workshop
Feb. 3, 2007
Maurice Tedderwww.Robofest.net
2chung
Student Assistant
• Emily Trudell and Joe Long• Sat. 9AM-12PM
3chung
Agenda• Intro to RCX• Intro to RoboLab • 9 Class Missions (somewhat related
to the Robofest Game 2007)• Programming Tips
4chung
LEGO MindStorms 101
5chung
LEGO MindStorms® Overview – Robot Command Explorer (RCX/Brick)
Hitachi H8 16MHz 8-bit microcontroller with 32K ext. Ram
16K ROM contains power up driver
16K of firmware can be downloaded to extend the on-chip driver
User programs are downloaded to the RCX as byte code in 6K region of memory
Firmware executes and interprets the byte code of programs when instructed
6chung
LEGO MindStorms® Overview – Robot Command Explorer (RCX/Brick)Infra-red (IR) Receiver Is a sensor that accepts the
program being transmitted from the IR tower. Also transmits data.
Sensor Input Ports Input ports 1, 2, & 3 are used to attach sensors to the RCX (0V/0 – 5V/1024 A/D)
View Button Used to obtain feedback from the input and output ports
On-Off Button Manually turn the RCX on and off
Motor (output) Ports Use output ports A-C to connect any combination of motors
LCD Display Display different values and information regarding the RCX and programs
AC/DC Power Input The RCX can be powered by plugging into a 9 Volt adapter (not for recharging batteries)
Program Button Used to switch between programs 1-5
Run Button Press the Run button to activate and run your current program
Speaker (not shown) Internal speaker indicates RCX status and acts as a programmable sound output
7chung
What Is RoboLab?
• A ‘Graphical’ programming language For the RCX based on LabVIEW
• In 1997, LabView was used for Sojourner project
• By designing a flow chart with given icons the programmer can program the RCX
8chung
Writing a new program
Click on the Programmer button.You should then see the Inventor login screen. Double click Inventor 4 to get full RoboLab environment.
Introduction to RoboLab – Programming Environment
9chung
ROBOLAB Environment
• Set up your screen in Inventor 4 so that it looks like the screen to the right.
10chung
ROBOLAB Environment
• There are two major pallets that contain most of the icons and commands you need to build a program.
• If you cannot see these pallets, you can find them under the Window -> Show drop down list.
Tools
Functions
11chung
RoboLab Workspace
Functions Palette – Contains
Icons for all possible
RCX program
commands. Icons vary with Level
Tools Palette – Contains Icons for building a
program diagram in the RoboLab
workspace
Context Help –
When this window is
open it displays
Help information about the Function
Icon under the mouse
cursor
Example Program –
All programs begin with a Green light
and end with a Red light
Icon
Search – Click the Search tab to find a Function
Icon in the Functions palette
Menus
Sub Menu Icons – Icons with the right side black dot have sub
menuIcons
12chung
Tools Palette
Operate Value tool: Change values in the Workspace window
Wire Tool: connect icons in your program from start to
finish
Set/Clear Breakpoint: allows you to suspend the execution of your program
Set Color Tool: allows you to set the colors of objects in the Panel and Diagram windows
Scroll Window Tool: move around in the Title or Workspace windows
Arrow Tool: move, delete, or place icons in workspace window
Automatic Tool Selection: Automatically senses correct
tool to use
Get Color Tool: allows you to copy a color from an image and use it as part of the color palette
Probe Data: allows you to check the program for values
Object Popup Tool: modify settings for
items in the Workspace window
Edit Text Tool: edit or insert text boxes
13chung
RoboLab Programming Elements• Forks – equivalent to if/then selection
structures• Task – run multiple task simultaneously (8
max.)• Wait states – program execution will be
halted until the wait state condition is satisfied
• Loops – to create repetition structures in a program
• Subroutines – a segment of code that can be called repeatedly from another code segment (8 max./program slot)
• Events – jumps to the specific section of code when the specified event occurs
14chung
RoboLab Capabilities I
Read Analog input values Output PWM on the output ports Subroutines Multitasking Event monitoring Multimedia Image/sound processing and
capture Access all RCX Brick input/output
interfaces (buttons, LCD screen, etc.) Music and sound functions
15chung
RoboLab Capabilities II
Data logging (2000 pts. @ 100Hz) and processing functions using G-Code (can compute basic statistics to derivatives and integrals)
Basic Logic and Math functions Variables (47 total, 22 user variables) IR Communication functions Direct program control functions Internet functions User defined libraries LASM functions (LEGO assembly language) Control lab interface functions
16chung
Pros to Using RoboLab
• Easy to see control structure• Visual interface is simple• Exactly like LabVIEW• Data gathering and visualization
(investigator)
17chung
Cons to Using RoboLab
• Spaghetti code• Hard to wire icons…• No edge triggering supported
18chung
For More Information
• LEGO’s Pagewww.lego.com/dacta/robolab
• National Instruments Pagewww.ni.com/robolab
• Tufts Universitywww.ceeo.tufts.edu/graphics/robolab
• www.lego.com/education/mindstorms/images/eng/downloads/compare.doc
19chung
What is a computer program?
A list of instructions created by a computer programmer (you) that tell a computer what to do next
Your job as a computer programmer is to: Decide how to get from point A
to point B using a bag of tricks (instructions)
For the LEGO Robot, instructions = Picture Icons connected together to form a program
•A (what I want the program to do)
•B(program doing what I want it to do)
LEGO RoboLab Function Icon
Palette
20chung
An Introduction to Structured Programming(or How to get from point A to point B) Structured programming philosophy states that all
programs can written using only three single entry/single exit control structures
1. Sequence structure: is built into RoboLab and means that statements are executed sequentially one after another as along the chain of connected icons
2. Selection structure: chooses between alternative courses of action (makes yes or no decisions)
3. Repetition structure: tells which actions are to be repeated while some condition is true
Programs are built in structured programming by stacking and/or nesting as many control structure building blocks as needed to solve the problem
21chung
RoboLab Control Structures
SequenceLoop/Repetition : Decision: Fork
Subroutines:Multitasking:
22chung
Ex 1: Go forward 2 seconds and come back by reversing motors
23chung
Making Turns
• Turn left:
• Spin left: (point turn)
• Face left:Left wheel
Left wheel
Right wheel
Right wheel
Left wheel Right wheel
stop
stop
24chung
Ex 2: Go forward 1.5 seconds and come back by spinning left
• Spinning 180 degrees?• Is it accurate?
25chung
Tips• How to insert icons?• How delete icons?• How to save programs?• How to use the Icon search feature?• Cover the tower and RCX when
downloading, if more than one robot in a room!
• Use Meaningful file names• Add Comments using “A: edit text”
26chung
Sensors•Light•Touch• Rotation • Temperature• Timer – Internal sensor• RCX buttons
27chung
Light Sensor
• Percent mode 5% - lowest dark 100% - very bright
• Reflected light mode: shines a red light
• Use View Button
28chung
Light Sensor Readings
Source: HighTechKids.org
29chung
Attach a Light Sensor
• Facing down• Gap: around 1 cm (What will be the
problem if less than 1 cm to solve the Miner Rescue problem?)
• Port No. 1
30chung
Ex 3. Go straight until the edge of the table is detected. Then stop the robot
31chung
Stop when it sees the black line on the Miner Rescue field• Measure and record the following
values White shelf Black line Foil Outside Edge Start of the ramp from the miner field
and the home base: why? The big gap!
• Suggested to lower the power level move down slowly
32chung
The gap between the Light sensor and the floor!!!• Both Reflected and Ambient light
values are affected by the distance between the sensor and the floor!
• The light sensor value is in inverse proportion to the gap
Lightsensor
Lightsensor
33chung
Stop when it sees the black line on the Miner Rescue field
34chung
Ex 4. Stop when it sees the 2nd black line on the Miner Rescue field
What went wrong?
35chung
How about stopping at the 4th line?• Loop (Repeat)
Block
36chung
Touch Sensor
• If released (not pressed): 0• If pressed: 1• Is it very sensitive?
37chung
Attach a Touch Sensor
• Port No. 2
38chung
Ex. 5 Loop until a touch sensor is pressed
Display seconds until touch sensor is pressed.
39chung
Line following - Zigzag methods
40chung
Ex 6. Follow the black line until a touch sensor is pressed
41chung
Ex 7. Follow the line until it detects the foil
• Need max power to climb
42chung
Ex 8. Follow the line until it climbs back to the home base
43chung
Ex 9. Follow the line until it climbs back to the home base – Use Subroutines
44chung
Not covered advanced topics
• Variables
• Multiple tasks & Synchronization of multiple tasks
• …
45chung
Tips for Robofest 2007 Game
•Line following may be needed for RCX
• Light sensor needed for detecting balls in the tunnel or edge
46chung
Tips for RoboSumo
• Light Sensor to detect the ring edge
• Touch sensor to detect the opponent
• Theories in physics