Tips for Passing Inspection George Mellors Teacher Engineering former Industrial Engineer Electrical Safety Hazards Electrical Components System DesignPlanning Resources Questions Agenda ID: 787466
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Slide1
Electrical SafetyBasic Electrical Practices andTips for Passing Inspection
George Mellors
Teacher Engineering former Industrial Engineer
Slide2Electrical Safety (Hazards)Electrical ComponentsSystem Design/PlanningResourcesQuestionsAgenda
Slide3Electrical HazardsBattery AcidElectron Flow CurrentShort CircuitHigh current hazardSparksElectrical Fire(s)In competition, Moon rocks, a robot in the Hartford competition was burned badly by an electrical fire.
Slide4Amps .vs. Injury in electricutionNote on right, it only takes 0.1 AMP to 0.2 AMP for potential Death.
Batteries used in FIRST FRC competition are sealed
Lead-Acid batteries. They can produce a 50 AMP current.
Slide5Battery SafetyBatteries used in FIRST Competition contain Sulfuric AcidWhile handling, working, cleaning up from accidental situations with a batteryWear Personal Protective Devices (PPD)Safety EyewearProtective gloves, rated for battery acid
Apron, again rated for protection against battery acid
No jewelry which could conduct electricity
Handling Upright and away from cloths and body
Slide6Battery Safety(continued)Do you have a Battery Spill Kit?WWW examplehttp://www.uline.com/Product/Detail/S-19486/Sorbents-and-Spill-Control/Battery-Acid-Spill-Kit?pricode
=WY233&utm_source=
Bing&utm_medium
=
pla&utm_term
=S-19486Q&utm_campaign=Janitorial%
2BSupplies
Do you have an emergency eye wash kit?
WWW example
http://
www.wayfairsupply.com
/Sperian-Safety-Wear-Saline-Personal-Eyewash-Bottle-FND320004520000-L2389-K~ZHK1030.html?refid=MX2649490155-ZHK1030&device=
c&ptid
=
1104000081468
Slide7Battery Current OverloadsCommonly Called Short CircuitsA short circuit occurs when the resistance in the circuit is very low or zero. Using Ohm’s Law this results in very high current.It will be as high as the source allows.In San Francisco in 2001, a electrical repair crew on a sub station North of the city energized the sub station without removing the grounding strap. Put the entire city in darkness until the issue was resolved.
Slide8What happens with a Current Overloads (continued)Commonly Called Short CircuitsHow long is a short circuit?Possible dangerous outcomesSparksCurrent contact with, through, human bodyOverheat wires and electrical component(s)
Slide9Electrical SafetyElectrical FireClass C fire extinguisherBattery HandlingGloves, Safety Glasses, clear path for transportationBattery Spill ResponseConnection
Using FIRST connectors and proper wire gauge
Tape, Tape, and more Tape… NO copper showing
Slide10Electrical Control System & Components
Slide11Robot (PLC) Rio, Robo Rio
Slide12Robo Rio (continued)Robo RIOPowerful computer Control SystemInterfaces
with control computer and robot system
Programming
Java, C++,
Labview
Module Order and placement matters
Camera (x-over) = Port 1
Radio = Port
2
Slide13Speed ControllersPWM Signal is sent to control motor speedsOne controller per motorTwo types exist:Victor 884 Jaguars (black new for 2010)AdvantagesIn the program for a long time
Easy to program
Disadvantages
Manual break/coast jumper
Hard to calibrate
Victor
Slide14Black JaguarNewer TechnologyBetter low end controlMore featuresRead rulesUnknown reliabilityLarger footprint
Victor 884
Older technology
Well tested
Very reliable
May be phased out in the next couple of years
Motor Control Workhorses
Slide15Talon SRXAdvantagesCAN supportInternal limit sensorsBreak/Coast ButtonCalibrate ButtonDisadvantages
Connection/Application of 10 pin
connector
Wires are short.
Challenge – Programming CAN
Slide16New Victor SPAdvantagesPWM controlBreak/Coast ButtonCalibrate ButtonDisadvantagesNo external input controls
Wires
are short
.
Would be used on simple control high amperage control.
Slide17Relay moduleAdvantagesProgrammed easilyOn or Off
only
Outputs can be easily reversed
Can control
Compressor
Solenoids for cylinders
Small PM Motors
Disadvantages
Limited Amperage (fused)
Spike
Slide18Control Table for Software EngineeringOutput fromWhat does it control and howSpecial Considerations Servos (6V)SpeedDiagram if possible
Slide19What kind of control?CANPWMOn-OffFeedback ? If so from wereBuild in software ?Labels
Slide20Step 1Read the ENTIRE rulebookThink about the robot designHow many motors?Which speed controllers?How many sensors?Safe wiring paths?How much space should be put aside?One board or multiple locations?
Electrical System Design
Slide21Step 2Discover how much space is allocated for the electronics once the robot is designedConsider preparing an early schematicElectronics should be protected, but easily accessibleVelcro panel, zip tied coverRadio should not be enclosed, keep from noise
Electrical System Design
Slide22Step 3Get all components laid out nicely Non-conductive platform (wood/fiberglass/lexan)Think about wire paths (bend radius and #)Leave room in case you need to add somethingTry to group related components to shorten wiresUse proper wiring color conventions
Red/white/brown = Positive : Black/blue = Negative
Labels!
Assist troubleshooting and inspection
Electrical System Design
Slide23Step 4Bench top test the electronics if possibleBasic control system & programming testingMount into the robot when it is ready to moveSecure wires from motors/sensors to frameChassis must be isolated, no ground returnDesign a secure battery holder with quick accessRemember, Battery position matters! Help your CoG
Electrical System Design
Slide24Do inspections regularly during buildKnow the rules!Don’t crowd the inspector1-2 people interacting makes things easierNeat wiring and accessibilityMake sure all components are securedHave charged battery ready + no air pressure
Inspection Tips
Slide25Acceptable Wire Gages
Slide26Signal light proper operation + visibilityBattery Terminal Lugs need electrical tapeVoltage monitoring improperly wiredEasily accessible 120A breaker/Dump Valve
Common Inspection Failures
Slide27Plan for sensor expandabilityKeep a log of parts usedNice for keeping the budget for inspectionAlso keep a spec sheet of components for referenceWith your log as reference you can form your own schematic to assist in inspection/judgingSchematics are great for debugging especially when those who wired it aren’t around (off-seasons, future years)
Other hints
Slide28Batteries, put someone in control of chargingZip Tie/Velcro Anderson Battery connectors during the matchesAssign someone to preventative maintenanceMake sure zip-ties aren’t breaking, battery holder loosening, etcCheck that your radio is plugged into the Robo RIO!
General Things
Slide29Usfirst.orgGet the Inspection Checklist and FRC SuggestionsChiefdelphi.comGreat forums for asking anythingAndymark.bizPurchase electronics/gearboxes/chassis/miscIfirobotics.comPurchase Victors/Spikes/Wheels
Resources
Slide30Questions?Thanks for attending!