1. 7 steps to autonomous for FRC
LabVIEW programmers
Jim Chastain
jimc2550@gmail.com

2. PingPong BunnyBot
• WE HAVE ENCODERS ON OUR WHEELS
• We want Arcade manual control (single joystick)
• In autonomous we want to use TANK control
• AND A SOLENOID “CLAW” TO HOLD OUR BUNNY
• IN AUTONOMOUS, WE WANT TO DESIGN A STATE
MACHINE WHICH WILL :
– MOVE FORWARD 10 FEET
– TURN RIGHT
– GO FORWARD 3 FEET
– OPEN CLAW TO DROP BUNNYBOT
– THEN STOP AND WAIT FOR TELEOP

3. 7 steps to Autonomous
• 1 Create list of all variables needed for autonomous
– All inputs (encoders)
– All outputs (drive motor signals, solenoid controls, encoder reset)
– Add a Boolean “Auto Enable”
• 2 From this list, set up an indicator in Robot Global Data for each
one ( In Robot Main.vi assign value to “Auto Enable”)
• 3 In “Timed Tasks.vi” read all sensors including joystick.
• 4 Create a CASE struct in Timed Tasks.vi and use “Auto Enable”
to switch controls between signals from “Autonomous” and
“manual” control
• 5 Make a list of all steps needed in autonomous, include steps to
reset encoders; put steps in STATE CHART (4 columns)
• 6 Build LABVIEW STATE MACHINE in Autonomous
• 7 Use Robot Global Data to Debug

4. set up list of auto variables
• Autonomous inputs
– Right and left encoders
• Autonomous outputs
– Auto drive right
– Auto drive left
– Auto sol Close (close solenoid)
– Auto sol Open (open solenoid)
– Auto enc reset (reset both encoders every time)
• We also want a signal “Auto Enable” to be on Robot
Global Data
• THIS GIVES US A SINGLE CONTROL SIGNAL WHICH CAN BE
USED to switch manual to auto.

5. From list, create indicators on
Robot Global DATA
YOU MUST SAVE AFTER
UPDATING RGD

6. Read all sensors (and joystick)
in Periodic tasks.vi
I used the 10 ms loop, but
changed it to 20 ms

7. AUTO ENABLE GETS VALUE IN ROBOT
MAIN.VI
TRUE IN AUTONOMOUS,
FALSE ALL OTHER STATES

8. CREATE CASE TO SWITCH
CONTROL SIGNALS
THIS CASE SWITCHES
CONTROL FOR MOTOR
AND SOLENOID
FALSE MEANS MANUAL
CONTROL

9. TRUE MEANS
AUTONOMOUS IS
CONTROLLING

10. NOTE, WHEN I CONTROL DRIVE MOTORS IN PERIODIC TASK, I MUST DIASABLE CONTROL IN
TELEOP.VI

11. LIST OF STEPS FOR
AUTONOMOUS
• 1 START WITH WHEELS STOPPED, CLAW CLOSED; RESET ENCODERS
• 2 GO FORWARD 300 REVOLUTIONS ON BOTH ENCODERS
• 3 STOP, RESET BOTH ENCODERS, (wait 20 ms)
• 4 RIGHT WHEEL STOPPED, LEFT WHEEL FORWARD 25 REVOLUTIONS
(HALF SPEED)
• 5 STOP, RESET BOTH ENCODERS (wait 20 ms)
• 6 GO FORWARD 95 REVOLUTIONS ON BOTH ENCODERS
• 7 STOP, RESET ENCODERS, OPEN CLAW (wait 20 ms)
• 8 WAIT FOR MANUAL CONTROL
• NOW PUT IN STATE CHART WITH 4 COLUMNS
– LEFT COLUMN IS STATE NAME
– NEXT IS STATE OUTPUT
– NEXT IS TRIGGER TO GO TO NEXT STATE
– FINAL COLUMN IS NEXT STATE (if you do not count notes)

12. L = Auto Left; R = Auto Right; RS =
encoder reset; Open & Close = Solenoid STATE CHART
STATE NAME OUTPUTS TRIGGER NEXT STATE NOTES
START L=R=0; None TWO
RS=true;
Close=True
TWO L=R=.-4 ENCODERS = THREE TRICKY STEP TO
RS = false 300 STOP EACH
Close =false MOTOR
SEPARATELY
THREE L=R=0;RS=true 100 ms FOUR
FOUR R=0; L=-.3;RS=f ENCODER=25 FIVE
FIVE L=R=0; RS=t 100 ms delay SIX
SIX L=R=-.4;RS=f ENCODERS =95 SEVEN AGAIN, TRICKY
SEVEN L=R=0;RS=t; 100 ms delay END
Open =true
END L=R=0, RS=f 100 ms delay END
Open = f

13. BUILD LV STATE MACHINE
• IN AUTONOMOUS
– PUT LARGE WHILE LOOP
– IN CENTER PUT MEDIUM SIZE CASE STRUCT
– PUT GLOBAL OUTPUT VARIABLE ON RIGHT
– PUT GLOBAL INPUTS ON LEFT
– CREATE ENUM (numeric pallet)
• Edit items to enter all STATE NAMES
– CONNECT ENUM TO “?” OF CASE
– CHANGE TUNNEL THRU WALL TO SHIFT REGISTER

14. BASIC BLOCKS IN AUTONOMOUS
Leave original
autonomous code
disabled
OUTPUTS
INPUTS
WHILE LOOP
CASE

15. NOW ADD ENUM
ENUM FROM ‘NUMERIC’ MENU,
RIGHT CLICK, EDIT ITEMS, INSERT
STATE NAMES FROM CHART!
ENUM GOES OUTSIDE WHILE, ON LEFT

16. COMPLETE FRAMEWORK
CONNECT ENUM TO ? RIGHT CLICK ON CASE
OF CASE; CHANGE CONTROL BOX, ‘ADD CASE
TUNNEL TO SHIFT REG FOR EVERY VALUE’

17. COMPLETE CONTENTS FOR EACH
STATE… FROM CHART

18. State TWO

19. State THREE

20. State FOUR

21. State FIVE

22. State SIX

23. State SEVEN

24. State END

25. DEBUG USING RGD
• Robot Global Data can be very useful in debug
if you include a STATE indicator (here is how)
– Put an indicator on the STATE line (right side of while loop)
– Right click on it (find) to locate it on front panel of Autonomous.vi
– Then copy it to Robot Global Data , call “current State”
– Delete it from the Block Diagram and replace it with Robot Global
Data.. See next three slides.
• Now when you run the robot in Autonomous mode, you can
watch Robot Global Data and see if things run in the correct
order.

26. Create an indicator on the STATE
variable line
Then right click on it and
‘find indicator’

27. Then put a copy on front panel of ROBOT GLOBAL
DATA

28. Label the Enum, “Current STATE”,
Save RGD
Delete the first enum indicator
Connect the RGD to the state variable
line.

29. NOTES
• I used 100 ms as a time delay just to let
everything rest before going to next state
(where there is a delay)
• Shoot me an email if you have questions
• Good luck!