Transcript Understanding the FRC Robot Controller

Understanding The 2008
FRC Robot Controller
Chris Gregory
FRC1089 – Team Mercury
www.mercury1089.com
Agenda
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
What I will I learn from this workshop?
What is the Robot Controller?
How do we communicate with it?
Robot States (Modes)
How does it connect to the rest of your
robot?
Tips & Tricks
Additional Resources
Q&A
I. What will I learn?
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How the RC interacts with devices in
the FRC competition, on and off the
field
How to correctly set up your Robot
Controller within your robot
The procedure for downloading code
to your robot
Tips and Tricks to help you along the
way
II. What is the Robot Controller?
II. What is the Robot Controller?
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“Heart and Brains of Robot”
Contains a PIC processor calculating
at 10.0 MIPS, with 128k
programmable flash memory
Programmable in C using a C18
Compiler
What you’re here to learn more
about
III. How do we communicate with
the RC?

RC Interfaces with Operator
Interface (OI) via three methods
• Radio-Controlled using your radios
(practice)
• Connected via Tether Cable
• Radio-Controlled via the Competition
port (At the events)
Connected Via Tether Cable
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Robot receives input from OI and controls
parts of the robot based on the
programmable code
Robot sends data BACK to OI such as
battery voltage, which motors are
running, etc.
Use the tether to synchronize your OI and
RC, as well as to set your team number
Don’t screw the tether in!
Connected Via Tether Cable
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Connected this way, the OI does not
require a power source, as it is run
from the robot’s battery
Not a good way to drive the robot
around, as the stock tether is only 6’
long
DON’T SCREW THE TETHER IN!!!!!
Radio-controlled (Practice)

Radios connected to both RC and OI
• (Use a tether cable first to synchronize them
the first time you use them)
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Useful for testing at home, but no radio
control allowed in pits at competition.
Operator Interface requires external
power (included in KOP)
Screw the radio into the robot, and keep
your radio exposed (BUT NOT
VULNERABLE)
Radio-Controlled at the
Competitions
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At the competition, the field controls
which status your robot is in through
the competition port on the OI
Field Techs will shut your robot down
if they deem it unsafe
You don’t use your OI Radio or power
source, those are provided through
the competition port
IV. Robot States (Modes)

Disabled
• How your robot starts and ends in a round
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Autonomous
• Robot controlled through programming
routines. USUALLY at the beginning of a
round.
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Tele-operated (Practice)
• Normal robot state: students control the
machine via the OI

Program
• How you download code to the robot
IV. Robot States (Modes)
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Practice Mode is set by default on powerup if tether cable connected
Disable Mode is on by default on
competition field or if no radio/tether
connected
Program Mode enabled by pressing
Program button on RC for 4 seconds
Disable/Practice/Autonomous mode can be
toggled via a MODE SELECTOR SWITCH
that you must purchase/create/obtain
V. How does it connect to the rest
of your robot?
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Main Battery (See Electrical
Diagram)
Backup Battery
Status/Team Lights (See Manual)
PWM (Analog) Outputs
Relay (Digital) Outputs
Analog Inputs
Digital I/O
Backup Battery
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7.2V battery pack used to stop RC
from resetting if main power is too
low
THIS IS REQUIRED FOR USING
SERVO MOTORS ON YOUR ROBOT
PWM Outputs
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Pulse Width Modulation outputs
Primary used for controlling Victor
speed controllers and powering
Servo Motors
They are ANALOG outputs,
effectively allowing variable speed
and, in the case of motors and
Victors, multiple directions.
You’ll definitely use these to drive
Relay Outputs
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Digital Outputs that have 4 states
each (Forward on/off, reverse on/off)
Useful for devices that only are fully
on or off (such as the air compressor,
a solenoid, or a lower-power motor)
By default, most are controlled by
push buttons on your OI joysticks
Analog Inputs
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These are typically used to hook up
to more advanced sensors, such as a
sonic range finder, a potentiometer,
or a gyro sensor
Allow for more detailed feedback to
the Robot, as opposed to an on-off
switch
Digital I/O ports
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These ports can be assigned IN CODE as
input or output, but by default, they are
all set as INPUT.
Typically used for switches on the robot,
such as limit switches, the air pressure
switch (which shuts off the compressor if
you hit the max PSI in your tanks)…
… or autonomous routine switches (if you
wanted to have multiple autonomous
routines that you could select by flipping a
switch on your robot)
Flux Capacitor
Just Kidding!
VI. Tips and Tricks
(mostly learned from other teams’ mistakes)
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Do not drink liquids around your robot
controller
Make sure that your robot controller’s
ports are easily accessible at all times –
you’ll never know when you need to
program or tether quickly
The backup battery will need a home – try
to create a means to secure it, as the
connection is a bit “flaky”
VI. Tips and Tricks
(mostly learned from other teams’ mistakes)
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Label your PWM cables!!!! You may find
that you need to disconnect a cable, and
you need to be able to plug them back in
the right spot.
Invest in, or create your own
autonomous/disable switchbox. This will
help with testing, as well as safety
Keep your wiring clean!
Always keep backups of working code!
VI. Tips and Tricks
(mostly learned from other teams’ mistakes)
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FOR THE LOVE OF GOD, DO NOT SCREW IN
YOUR TETHER CABLE!
Treat your robot controller as if it cost you
$449.95 plus shipping and handling, because
that’s how much it costs to replace it.
Secure your RC in a place that the tether port is
easily accessible: You will be required to operate
in this mode at the competitions
Invest in extra: Main and Backup Batteries,
Tether Cables, Victors and Spikes
VII. Additional Resources
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AndyMark – www.andymark.biz
• Place to purchase reliable mode selector
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IFI Robotics – www.ifirobotics.com
• Manufacturer of RC – contains other guides
and manuals, as well as links to programming
guides and resources
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ChiefDelphi – www.chiefdelphi.com
• Team 47’s homepage, considered the unofficial
FIRST “hub”, contains a lot of useful resources
on forums. Don’t forget to use the Search
button!
VIII. Q&A
WELCOME TO FIRST!!