1. Lockheed Martin Space Systems Team 1913, Covington High School
Electrical Subsystem
Scot Marshall Lead Manufacturing Test Engineer Constellation Project / Orion CEV
Lockheed Martin Space Systems
Michoud Operations
Team 1913, Covington High School
Covington, LA

2. 2006 IFI Hardware 3 6 5 9 9 4 5 2 8 1 7

3. 2007 Version

4. This Schematic is available at
Power Distribution
This Schematic is available at

5. IFI Hardware Robot Controller Operator Interface
Wireless RS Channel Receiver
Back-up 7.2 VDC Battery
CM2 Camera
Operator Interface
Wireless RS Channel Transmitter
Power Supply
Tether
Power Distribution Panel
Resettable Circuit Breaker (20A, 30A, 40A)
Robot Controller Interface
Cabling
Serial Computer Interface

6. 1. Operator Interface Inputs Outputs Special Instructions 12 VDC Power
(4) Joystick
Competition Port
Team Number
Radio Modem
Outputs
Dashboard (PC)
Tether
Special Instructions
No external power needed when Robot is tethered
Diagnostic Indictors for Robot and Operator Interface

7. This information is available at
Operator Interface
Competition
Tether
To PC Serial Port
Radio
Joystick
Joystick
Joystick
Joystick
Robot Reset
Disable Channel
Display Select
Team Number
OI Reset
This information is available at

8. 2. Robot Controller Inputs Outputs Special Instructions Digital Signal
Analog Signal
Radio Modem
Tether
Serial
Programming
Outputs
Relay
PWM
Special Instructions
Use Breaker
Wire ON when Robot is powered
Use Backup battery also

9. This information is available at
Robot Controller
PWM Outputs
Team
Color
7.2 VDC Backup Battery
12 VDC Battery
12 VDC Battery
16 Analog Inputs
Program
Black
Red
Wh/Yel
= Ground
= +5 VDC
= In/Out
Tether
Tether
18 Digital In/Out
Radio
Relay Outputs
Serial
Input
Pgm
Reset
This information is available at

10. 3. Breaker Panel Inputs Outputs Special Instructions
12 VDC from Battery
Outputs
Power Distribution
Ground Plane
Serial to Robot Controller
Special Instructions
Wire through Main Breaker
Terminals Numbered
G is Ground
40 is for 40A
Wire straight into 40A (Drive Motors)
Use Spade lugs for 30A & 20A

11. Breaker Panel 40A and 30A Breakers Installed (6) 40A Breakers
40A wires attach under screw plate
Power & Ground
30A or 20A Circuits 24 places
MainBattery +12 VDC
Red/Green/Orange Status Indicator
PWM Cable
Main Battery Ground
Terminals use spade lugs
Reset
Serial to Robot Controller

12. 4. Circuit Breakers and Fuses
20A, 30A, 40A
Push/Pull Installation
Overcurrent (thermal) cutoff
Resets as soon as condition is resolved
Fuses
20A for Spike Relay
One-time use
Look for broken loop
Same as for Automobile
30A
20A
Fuse Element

13. 5. Wireless Modem (Transmitter)
Inputs
9600 Baud RS-422 Data
Outputs
MHz Band - 40 Channels
Special Instructions
ft Range
35 Competition Channels
Default (Practice) Channel 40
2 robots on Default will interfere
01, 04, 13, 22, 31 User Settable Channels
Requires Robot Master Code Ver. 13

14. 6. Victor 884 Speed Controller
Inputs
Digital PWM
+12 VDC, Ground
Outputs
Variable Current
Special Instructions
Use 40A Breaker
Use for CIM Drive Motor
Wire fan ON when robot is powered

15. Victor 884 Speed Controller
Fan – GND
Battery – GND
Battery +12 VDC Fan +12 VDC
Motor – GND
Motor + Power
PWM Cable
Wh Rd Bk
(Fits Poorly)
Red/Green/Orange Fwd/Rev/Active Indicator
Brake/Coast Jumper
Cal

16. 7. Spike Relay Inputs Outputs Special Instructions Digital PWM
+12 VDC, Ground
Outputs
Full Fwd
Full Reverse
Brake
Special Instructions
Use 20A Breaker
Use for Motor Drive
Fuse
Red/Green/Orange Fwd/Rev/Active Indicator
PWM Cable

17. 8. CMUcam2 Camera Rev. A Inputs Outputs Special Instructions
PWM Power from RC
Outputs
RS-232 DB9 to Computer
RS pin Serial to RC
Servo Control
Special Instructions
Use PWM 7.2 VDC Supply
Use for Motor Drive
Connect Only 1 RS-232 at a time

18. CMUcam2 Camera Rev. A Servo Outputs Deleted RS-232 to PC for GUI
RS-232 to Robot for Auto
PWM Cable Connector
Focus by Rotating
Red/Green LED Indicators
RC Board Connector
On/Off
RC Power
This information is available at
manual

19. 9. Cables PWM Cable DB9 Tether Digital Signal Joysticks
Serial Communications
RS-232
RS-422
Tether
Digital Signal & Power

20. Wires Wire Gage Color Code Safety Main Power – 6 AWG or larger (4 AWG)
40A – 10 AWG
30A – 12 AWG
20A – 14 AWG
Color Code
Red/Blue - 12 VDC Power
Black/Yellow – Signal Return
Green - Chassis Ground
Safety
Insulate all connections

21. Documentation FIRST Robotics Website IFIRobotics
2006 Manual – The Robot
IFIRobotics
Robot Controller
Operator Interface
Breaker Panel
RS-422 Modems
Victor 884 Motor Controller
Spike Relay
Camera

22. Robot Controller
FRC Control System Overview(pdf) , Used for Robot Controllers Installation Info (pdf) Size and mounting info FRC System Quick Start, Used for Robot Controllers Reference Guide (pdf)  , Used for Robot Controller Analog and Digital Input (pdf)  schematic Program Port Pin-out (pdf)  schematic

23. This information is available at
Operator Interface
Specifications Description 2005 Reference Guide (pdf) Installation Info (pdf) 2004 FRC System Quick Start (pdf) 2004 FRC Control System Overview (pdf) Competition Port Pinout Guide (pdf) RevA Frequently Asked Questions (FAQ) Legacy Docs
This information is available at

24. Backup Charts

25. Connectors

26. Motors

27. Compressor Inputs Outputs Special Instructions Digital Signal
Air Pressure
Special Instructions
Use Breaker
Wire ON when Robot is powered
Need Pressure Relief

28. Sensors
123

29. Switches 1 2
456

30. Chargers
7.2 VDC 1
Main Battery
456

31. Websites
7.2 VDC 1
Main Battery
456

32. Adapted from a 2004 Presentation
Michael Dessingue
College Mentor - Hudson Valley Community College
Team 250
Steve Shade
Controls and Simulation Engineer – Rolls-Royce
Teams 1111 & 7
Al Skierkiewicz
Broadcast Engineer - WTTW-TV
Team 111

33. Overview Electrical kit and IFI Hardware Layout and Planning
Resistance and Ohm’s Law
Electrical Tools
Myth-Busting
Questions

34. Documentation Example
Team 1111 Robot Controller Outputs
Outputs
Description
Color CB
B/C
PWM1
Drive Left
Red
40-2 C
PWM2
Blue
40-4
PWM3
Drive Right
Green
40-6
PWM4
Yellow
40-5
PWM5
Lift
Orange
40-1 B
PWM6
Brown
40-3
PWM7
Wrist
White
1-20

35. General Layout Tips Label and/or Color Code Everything
Secure wire so a hit from another robot doesn't stretch the wiring to a breaking point or pull a terminal out of a breaker, victor or spike
When in doubt, insulate
Secure the battery so it doesn't fall out
Leave some slack in wire to allow for swapping of parts
Be careful when running wiring through frame members so that mech heads don't drill into it at some point down the road

36. FIRST Electrical Problem
How much voltage is lost in a typical FIRST circuit?

37. Ohm’s Law + _ By Ohm’s Law: V = I * R 12 V = I * 24 W I = 0.5 A
12 V Battery
24 W

38. Typical FIRST Circuit + _ Victor 884 Speed Controller
120 A Circuit Breaker
Victor 884
Speed
Controller + _
40 A Circuit Breaker
Vout Measured
12 V Battery
Assuming the Victor 884 Speed Controller is given an input signal of 254 from the Robot Controller, how much voltage is output to the device?
Ideal Value
12 V
Actual Value
0V to ~11.63 V

39. Typical FIRST Circuit + _ Victor 884 Speed Controller
120 A Circuit Breaker
Victor 884
Speed
Controller + _
40 A Circuit Breaker
Vout Measured
12 V Battery
Circuit consists of 8’ of #6, 4’ of #10, and 2’ of #10.
14 Connections in the circuit
Ideal Value
12 V
Actual Value
0V to ~11.63 V

40. More Wire Adds More Resistance
“Standard Wire Foot” - A 10 gauge wire will drop about 0.1 volt per foot at the stall current of any of the drive motors.
There is resistance in every wire
.001 ohm/ft #10 wire
.0004 ohm/ft #6 wire

41. Typical FIRST Circuit
Resistances: 8’ #6 = W 6’ #10 = W Rtotal = W
Steady State Current: 40 A
Voltage Drop = I*R = 40 A * W = V
Max Voltage at Device = 12V V = V

42. Typical FIRST Circuit
Resistances: 8’ #6 = W 6’ #10 = W Rtotal = W
CIM Motor Stall Current: 114 A
Voltage Drop = I*R = 114 A * W = 1.05 V
Max Voltage at Device = 12V V = V
At Stall Current of CIM, Max Voltage at the CIM motor for the same current path is 10.95V!

43. Reducing Resistance
Check every crimp to make sure the wires do not move or turn when pulled
Use the correct tool for the job
Solder all critical joints
Shorten the length of your wires (also helps in keeping things neat and traceable)

44. Crimp Connections Buy a good crimper for about $20
Home Depot, Lowes Electrical Sections
Many Auto Parts Stores also stock crimpers
Look for crimper with good handles and can used with wire gauges 10 to 24

45. Soldering
Good Practice to solder all connections where high currents exist
Use Appropriate Size iron for the job
Use a Rosin Core Solder for all electronics
Wire Size
Min Power (W)
Max Power (W) 6 60
100+ 10 40 80 16 30 24 20

46. Other Required Tools Multimeter (DMM) Wire Strippers Voltage
Resistance
Continuity
Wire Strippers
Re-strip any wires where copper strands are lost

47. Myth-Busting

48. The RC, OI, Victors and Spikes need external components to run (i. e
The RC, OI, Victors and Spikes need external components to run (i.e. capacitors, voltage regulators, etc.)
IFI has done a good job of designing the power and internal circuitry of all the kit electronic components. There is no additional circuitry required for reliable operation. The fan that is mounted on the speed controller is required though and most teams will wire this fan to the controller power input. The fan then becomes an indication of good input power to the controller.

49. The controllers can’t go from forward to reverse quickly.
The speed controllers do exactly what you tell them to do. Your robot cannot make the sudden changes you are demanding for other reasons related to mechanical design and physics. You cannot hope that the control system will overcome all other losses. It does not have the power resources to overcome the momentum of a charging 130 lb. robot and change it’s direction.

50. The controllers and motors are not matched, the switching is all wrong.
This may seem to be the case, but the components work very well together. All teams use the same motors and drive components so there is no disadvantage to any team using the supplied parts.

51. The OI says my battery voltage is 10
The OI says my battery voltage is 10.5 but my voltmeter reads 12 at the battery. It must be broken.
Your RC voltage monitor accurately reads the voltage that is present at it’s input. If your RC reads 10.5 volts, there is considerable loss in the wiring and connections. Check that you have connected the RC to the #1 or #2 positions on the breaker panel and check that your connectors are well crimped and are tight and fully engaged on the push on connections.

53. The battery is too small.
The battery is actually very powerful. Most teams have no problem driving a 130 pound robot for more than two matches with the kit battery. If your robot drains a charged battery by the end of a match, the mechanical design is inefficient or you are using some form of tank drive. (treads or four or more non-steering drive wheels)

54. TYPE ES18-12
CAPACITY
5HR 3.06A 15.3 AH
1HR 10.80A 10.8 AH
1C 18.0A 9.0 AH
INTERNAL RESISTANCE APPROX. 15m
MAX. DISCHARGE CURRENT 230 A (5 SEC.)
MAX. CHARGE CURRENT 5.34

55. The main battery cannot be used lying down.
The main battery can be used in any orientation, including upside down. It can be charged in any direction except upside down. Battery terminals must be protected at all times and the battery must be secured in the robot. You can’t play when your battery is lying on the field.

56. A sparking motor is defective
Sparks are normal in DC brush type motors. The magnetic fields in a motor generate high voltages that spark across gaps in the brush assembly. Motors that are working hard or have worn brushes produce more sparking.

57. I can only get 11 volts at my motor running
I can only get 11 volts at my motor running. The breaker panel is defective.
This actually is an effect of the some of the principles discussed earlier. High currents in the wires we use result in some voltage drop. Measuring at the motor, is in effect, compensating for this loss. Remember the wire foot, every foot of #10 at stall drops 0.1 volts. A one volt drop is an indication you have 10 wire feet of loss on the robot between the battery and the motor. This could be two 10 gauge wires, five feet long, or four feet and a speed controller or three feet, a speed controller and a breaker and some connectors.

58. The backup battery is disconnected when you power off.
According to the RC manual, Team LEDs (and the backup circuit in the RC) will go out after four seconds if the RC has not established contact with an OI connected to the arena controller. If an arena controller is connected and a link has been established, the RC will shut down about four minutes after main power has been removed. The backup battery supplies current to the RC, modem, servos and team LEDs when the main battery has fallen below about 7.2 volts. You must hit reset to save the backup.

59. My Chalupa is only running a light load but it keeps tripping the breaker, the breaker must be defective.
A current monitor would verify what the motor current actually is. Many manufacturers make clamp on probes that will monitor current for use with you multimeter. If the motor current is high check that there isn’t a problem in the drive system by running the robot with the wheels off the ground. If motor current is normal, suspect bearing side loads, misaligned wheels, etc. If it is high, remove the motor from the transmission and try again, if it is high suspect a defective motor, if low, suspect a problem in the transmission.

60. I don’t need to insulate the black wire
The black wire carries the same current as the red wire it is paired with. By insulating both wires, you are “backing up the backup”. If the insulation on a wire fails, the insulation on the other wire keeps the electrical system safe. (backup the backup is a common method used by NASA and others to insure safety, reliability.) The black wire on the motors are not connected to battery negative all the time.

61. Main circuit breaker is vibration sensitive it needs to be shock mounted.
This was true of the old panel type breaker, but it is not true if the breaker supplied in your kit this year or last. These breakers were designed to be used in vehicles and boats. A few have turned up this season that were sensitive to light tapping on the red disconnect button. These are defective breakers and should be replaced.

62. Protect the radio by putting it down inside the robot.
It is important to protect the radio modem and the rubber antenna that sticks out the top. To mount it down inside all of the metallic parts, motors and transmissions, is reducing is ability to communicate with the OI modem. The robot modem needs to be mounted in a protected area with the antenna vertical and as far from metallic structures as possible.

63. The antenna on the robot can be anywhere in any orientation, same with the OI.
Antenna coupling is greatest when the antennas are mounted in the same orientation. Coupling is minimum when the antennas are mounted 90 degrees apart. The radios still appear to work but the margin of good signal is vastly reduced.

64. The IFI control system is awful, my robot keeps cutting out.
A robot that cuts out on the field is most often a result of input power to the RC falling below 7 volts. A high current draw when running will take the battery voltage down temporarily. The RC will go to backup and shut down while the input voltage is low. When it returns, the RC will act normally. Occasionally a modem problem may occur on the field, the IFI reps are monitoring every robot and can tell most problems from their monitoring station.

65. #4 wire is way better than #6.
This is partly true. If you are running a long distance with the primary wiring and you can stand the extra weight, then 4 gauge may be a good choice. Mating 4 gauge to the Anderson connector is a problem for most teams. For short runs and the best weight savings, 6 gauge is perfectly fine.

66. Soldering is better than crimping.
Manufacturers crimp contacts all the time and the military requires crimping only. The big difference is the crimp is made with a very expensive crimp tool or by machine. For our purposes, a soldered connection adds a little insurance to the connection. A good soldered joint is one that is mechanically sound to start with. Crimp first, then solder, then insulate.

67. A motor will run at free speed if you connect it to a battery.
The motor specifications are recorded under very strict testing guidelines and using equipment that takes away any variables in testing. The motor may get you close to tested specifications but don’t expect to duplicate results in your shop with a battery.

68. The electrical rules don’t meet electrical practice. (NEC)
The electrical rules attempt to follow NEC guidelines if you check the “open air” tables. This allows a #12 wire to be used in open air where a #10 for the same current must be used in conduit. I personally prefer to use #10 for all high current wiring on the robot, and #18 for the lower current valves and RC.

69. 7. Battery connectors are too small, underrated.
Although rated at 50 amps, the overall heat generated in the connector during a two minute match is low enough that teams do not need to worry. If the connector is improperly crimped, damaged or misaligned, or the robot design is significantly inefficient, some heating of the connector is possible and damage could be the result. I have seen little evidence of connector damage. Using alligator clips on the charger to connect to the Anderson battery connector will damage the surface.

70. 6. The main battery cannot be used lying down.
The main battery can be used in any orientation, including upside down. It can be charged in any direction except upside down. Battery terminals must be protected at all times and the battery must be secured in the robot. You can’t play when your battery is lying on the field. Also don’t pick up the battery by the wires, as internal damage will result.

71. 5. My four wheel drive robot eats batteries, there is something wrong with control system.
Four wheel or tank drive systems use incredible amounts of current when turning using high friction drive surfaces like belting or knobby tires. When a robot turns it must drag the wheels or treads sideways across the carpet. In a tight or fast turn, this high friction translates into near stall conditions for all the drive motors. The result is temporary current draw above 200 amps in a four motor drive. That may be enough to draw the voltage in the battery below RC minimum.

72. 4. The backup battery is not used when the main power is shut off.
According to the RC manual, Team LEDs (and the backup circuit in the RC) will shut down after four seconds if the RC has not established contact with an OI connected to the arena controller. If an arena controller is connected and a link has been established, the backup battery will still be connected to everything on the robot for up to four minutes after main power has been removed. With servos and LEDs, a lot of power is watsted. Press reset after every power off.

73. 3. The battery has memory and needs to be discharged to zero.
This is one of the most common myths. It arises from a particular type of NiCad battery behavior. Gel cell batteries do not have a memory that needs any special handling. Charge them normally with the supplied chargers and never at more than 6 amps.

74. 2. The battery is too small.
The battery is actually very powerful. Most teams have no problem driving a 130 pound robot for more than two matches with the kit battery. If your robot drains a charged battery by the end of a match, the mechanical design is inefficient or you are using some form of tank drive. (treads or four or more non-steering drive wheels). In a hard match or a restart, you may not have enough battery reserve to last two minutes.

75. 1. You don’t need to calibrate speed controllers.
The biggest myth of all. Do not believe this one. The speed controller has the ability to adapt to each joystick you use. Since each speed controller is not matched to the joystick you were shipped, they must be calibrated. Calibration gives the controller the ability to match the maximum travel on the joystick to the maximum output on the controller.

76. Planning Your Electrical System
Plan, create drawings just like mechanical systems
Create a test bed early
Use test bed to test all systems before integrating
Communicate effectively with the mechanical sub-teams early and often
Document everything