1. Become a Control System Detective
Troubleshooting at the Boundary Between Electronics and Programming
10th year mentor
CSA at Sacramento & SVR, 2013
CSA at ALL Regionals!! They are there to help.
WRRF Workshop
August 2013
Laura Rhodes, mentor, FRC Team 100

2. FRC Control System (on Robot)
All teams use same electronics.
Benchtop systems such as this invaluable for S/W development.

3. Driver Station (Windows PC)
Windows PC (works on other PC’s, not just FIRST supplied Classmates).
Joysticks are HID devices connected to PC by USB cables.
Runs Driver Station software to communicate with robot.
Ethernet or WiFI to talk to robot

4. Here’s what you’re supposed to do: Enable/disable Mode Operating Mode
Hey Robot-
Here’s what you’re supposed to do:
Enable/disable Mode
Operating Mode
Joystick commands
OK Driver Station-I’m ALIVE!!
Here’s my battery voltage and other data
Every 20 ms
Basic idea of robot/Driver Station communication.
Loss of comm. Link => robot motors disabled.

5. Tethered (Ethernet Cable)
In the pits, tether by plugging into free port on radio.
On the boards we have here, no radio is installed so can plug directly into cRIO.
Tethered
(Ethernet Cable)

6. Only can do WiFi at your own shop. Must tether in the pits.
Wireless
(WiFi)

7. Field Management System
FMS AP
Competition mode.
Extra delays compared with tethered in the pits – WiFi traffic
Field problems difficult to debug, both because FMS is a “Black Box”.
Demand and 2012 Einstein field problems forced FIRST to provide better diagnostic tools in 2013.
Due to 2012 problems, FIRST imposed WiFi bandwidth restriction on robot communications (7Mb/sec).
Field Management System
(Wired to FMS to WiFi)

8. Made by National Instruments. PowerPC married with Xilinx FPGA.
Write robot code in LabVIEW, C++, or Java on a PC. Cross-compile for the PowerPC and download application to flash memory on cRIO.
FPGA custom image provided by FIRST, defines H/W. Watchdog timer for disabling motors. High Speed counters (e.g. for encoders), analog sensing and accumulation (e.g. for gyros)
VxWorks operation system, WPILib libraries, NI libraries, and of course Team code run on PowerPC.
cRIO
(Robot Brain)

9. Power Distribution Board
Battery connection and custom regulated power for cRIO and other devices.
Note LED’s along sides that light up if circuit with load is tripped.
Power Distribution Board
(PDB)

10. I/O connection points for all signals to/from cRIO Digital I/O card.
37-pin connector to cRIO. Ribbon cables provided in 2012 were problematic.
Understand difference between PWM outputs, Digital I/O, Relay outputs.
Some sophisticated sensors use I2C port.
Digital Sidecar

11. (control voltage to motors)
Speed Controllers
(control voltage to motors)
All speed controllers do the same thing – provide a regulated voltage to the Brushed DC motors based upon “throttle” command.
Both forward and reverse operation allowed.
Another name is H-Bridge
Think of them as Voltage controllers, not speed controllers.
Two ways to send signals
PWM – hobbyist servo signaling (pseudo analog, pulse width defines speed and direction) – Jaguar, Victor, Talon – one way communication, no feedback
CANbus – Jaguar only – two way communication, status feedback

12. The 2 different ways Pulse Width Modulation is used
PWM vs. PWM
The 2 different ways Pulse Width Modulation is used
SIGNALLING – telling the speed controller what to do
POWER – controlling voltage and motor direction
H-Bridge
None – Motor free runs
S1 and S4 – Motor moves CW
S2 and S3 – Motor moves CCW
S2 and S4 – Motor brakes
Changing the duty cycle of switches controls the average VOLTAGE to the motors.
We casually toss around the term PWM – Pulse Width Modulation.
But actually this term refers to two completely separate concepts related to the Speed controllers.
The first is signalling the controller what to do. The white signal line on a “PWM Cable” is pulsed every 5 to 20 ms. The width of that pulse encodes what the speed controller is to do. (Pseudo-analog technique).
The second is how the switches are controlled on the H-Bridge. The switches are cycled at a high rate of speed (~20KHz on the Jags) and the duty cycle affects the average voltage to the motor. If on all the time, 12V. If half the time the switches are closed and half the time they’re open, it’s 6V.

13. Wireless Bridge (Robot Radio) New version (rev. B) required for 2013
NOTE THE 5V regulator. This was missed by many teams (and many inspectors!). Helps prevent radio dropout.
Mount away from motors, outside frame, vertical orientation.
At home switch set up as “AP”, at competition, set up as “BRIDGE”.

14. Motors
Brushed DC motors, hobbyist servos

15. Passing Inspection Point out page of hints in handout
Follow Robot Rules
Preinspect using FIRST provided checklist
Main breaker easily accessible
One motor per speed controller
One Wire per Wago connector
Lights that are supposed to be visible – make visible.
RSL proper operation
Robot frame isolated – cRIO and Camera are likely culprits if not.
Most up-to-date firmware, Driver’s station application, programming tools

16. Power Distribution Robot Rules – Wire sizes and colors
Schematic provided USE IT

17. Data Connectivity

18. Document your I/O I have a handout for this Do yourself a favor –
well documented I/O list
color coded connectors and/or tapes on wires
labels on both ends of every wire
Labels on motors and speed controllers

19. RobotBuilder New tool for 2013.
Very useful in design discussions when initially configuring robot actuators and sensors.
For example, to make sure design fits on a single digital sidecar.
Can be used to automatically generate C++ and Java code. Can be used in design iterations but care must be taken.

20. The drive train controls were responding correctly.
Then I tried raising the arm.
After that the arm controls responded but the drive train no longer responded to joystick commands.
I dunno- everything stopped working
When something goes wrong on the field, gather all clues
Try to reproduce problem in the pits, watch lights, dashboard & DS displays
Problems can be in software, electronics or mechanics:
Broken key or loose shaft collar set screw
Burned out motor or speed controller
Have known good test software ready for loading
Drive Team Feedback

21. Troubleshooting on the Robot
Lights, lights, lights
Dangling or connectors
Metal Shavings in Electronics(  !!!)
Troubleshooting guide in handouts – 5 pages (and there could have been more!)

22. Multi-Meter Know How to Use One
Ω – Ohms –Resistance (measure with battery disconnected)
V DC - Volts

23. Know your Lights
“Lights are your friends” page in handouts.

24. Robot Signal Light
Fast Blink = cRIO not communicating with Driver Station
Slow Blink = disabled
Short on/long-off Blink = either low battery or no code & disabled
Long on/short off blink = Teleop mode
Solid on = Autonomous mode

25. Jaguar Speed Controller
Solid Yellow = Neutral (zero speed)
Fast Flashing Green = Forward
Fast Flashing Red = Reverse
Solid Green = Full speed forward
Solid Red = Full speed reverse
Slow Flashing Yellow = Loss of CAN or servo link or Disabled
Slow Flashing Red = Fault
No light = no power (check power connection)

26. Victor Speed Controller
Solid Green = Full forward
Solid Orange = Neutral/Brake
Solid Red = Full Reverse
Flashing Orange = No PWM signal
Flashing Red = Failed Calibration
No light = no power OR partial throttle

27. Talon Speed Controller
Solid Green = Full Forward
Flashing Green = Forward
Solid Red = Full Reverse
Flashing Red = Reverse
Solid Orange = Enabled within deadband
Flashing Orange = No PWM signal or robot is disabled.

29. Troubleshooting on the PC
Hey programmers, look at the robot, TOO.

30. Driver Station Operation Diagnostics Setup
Will demonstrate these tabs later in demonstration
Setup

31. Driver Station (cont.)
I/O
Charts

32. Practice Mode & Test Mode
Practice mode very helpful. Can be used to make sure robot properly transitions from autonomous mode to teleop.
Test mode new for Works in conjunction with changes to programming environment. Used to verify that hardware hookup is as expected.

33. IP Configuration
Everything needs to be perfectly configured. Subnet Mask , IP address for DS computer 10.xx.yy.06 (xx.yy is team number), cRIO is 10.xx.yy.2, radio is 10.xx.yy.1, camera is 10.xx.yy.11.

34. ping cRIO – Are you there?? ping 10.xx.yy.02
If you can’t PING, you’ll never communicate using DS.

35. Dashboard LabVIEW Dashboard (default) SmartDashboard (C++ and Java)
LabVIEW dashboard entirely redesigned for I don’t have much experience with it.
However very useful for setting camera resolution and viewing bandwidth. (LabVIEW teams only)
Smart Dashboard much improved in 2013 for both Java and C++. New “test mode” functionality, well tied to the Command-Based Paradigm.

36. Driver Station Log Viewer
Be especially on lookout for problems caused by camera – vision processing, data rate (FPS and resolution)
Demo this live – using data from 2013 competition.
Normal match. Errors.
Use with practice mode to verify the controller doesn’t get stuck in Autonomous and properly transitions to teleop.
C:\Program Files\FRC Driver Station\ Driver Station Log File Viewer.exe

37. cRIO Imaging Tool
Use to load new image. Reload application after reimaging.
Will show if module is in wrong slot.

38. Programming Environment
LabVIEW
C++ (Wind River)
Choose a language and know how to use it before competition.
If no mentor available, I suggest either LabVIEW or Java.
C++ has too many gotcha’s for the novice.
Know difference between deploying (permanent) and debugging (temporary).
Java (NetBeans)

39. Axis Camera Configuration
Can also be done manually using camera’s internal webserver. See instructions from FIRST about configuring you IP address on the PC.

40. Measuring Bandwidth Usage
Keep wireless network traffic within 7Mb/s limit
perfmon.exe - Perfomance Monitor (Win 7 only)
Wireshark – 3rd party Ethernet packet sniffer
See ScreenSteps documentation for how to do this.
There are new bandwidth limitations. You can make sure you’re in compliance by using the Performance Monitor or Wireshark. (also on LabVIEW dashboard)

41. FRC Bridge Configuration Utility
DO NOT USE THIS UTILITY WHILE AT COMPETITION.
When you get home from competition, the wireless bridge will not operate properly for you until you reset it and then reprogram it. This is because special security modes were set up for the bridge to work with the FMS.
At competition – BRIDGE MODE
At home – AP MODE.

42. Recommended Reading

43. KOP Website http://www.usfirst.org/roboticsprograms/frc/kit-of-parts
Central source of all the documentation – go here first.
Links to other documentation, software updates, etc.
See main tabs at top:
KOP HOME
GET HELP
TECHNICAL RESOURCES
CONTROL SYSTEM
DRIVER STATION
PROGRAMMING
Check often during season for new information and software updates.

44. KOP Website – Control System
Getting Started with the 2013 Control System
Robot Power Distribution
Robot Data Connectivity Diagram
These are the documents to look at first.

45. ScreenSteps Live http://wpilib.screenstepslive.com/s/3120
NEW FOR 2013.
Extensive online documentation – can download as PDF.
Many levels – mine it deep!

46. RobotBuilder Demos - YouTube
Robot Builder is New for 2013.
Brad Miller (WPI) put together a set of excellent training videos on You Tube.

47. Einstein Field 2012 Report WiFi Tampering Loose Wiring Faulty breaker
Unregulated Radio power
Bad Ethernet cables
Bug in C++SmartDashboard
Infinite software loop initializing sensor
Custom Electronics flooding communications channel, filling buffer
NetTables bug
WiFi tampering probably not malicious
Unregulated radio power -> radio reboots in match

48. Let’s try it out on real hardware!
Real simple robot – no sensors, no autonomous, two joystick tank drive control, speed controllers on 1 and 2
Visual sweep before powering up, visual sweep of lights after power up.
Startup checklist in Handout
Start up Driver Station. Point out:
Communications light
Robot Code light
Battery Voltage
Team number
Enable/Disable
E-stop is “Enter key”
Space Bar disables robot
Charts – CPU usage, memory, packet losses