Difference between revisions of "DEWBOT VI Electrical"

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While the motors and pneumatics are the muscles of the robot, the wiring is the central nervous system.  Electrical wiring supplies power from the battery to the Power Distribution Board, from there to the Jaguar and Victor speed controllers and then on to the motors.  Wires also take signals from the sensors to the either the Digital Side Car (for on/off signals) or to the Analog daughter board (position sensors) for processing by the cRio.
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While the motors and pneumatics are the muscles of the robot, the wiring is the central nervous system.  Electrical wiring supplies power from the battery to the Power Distribution Board, from there to the Jaguar and Victor speed controllers and then on to the motors.  Wires also take signals from the sensors to the either the Digital Side Car (for on/off signals) or to the Analog daughter board (position sensors) for processing by the cRio.  This page covers the details of the Electrical system, please see [DEWBOT VI Electrical Team] for the build season notes.  
  
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== Week 1 Progress ==
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== DEWBOT VI Technical Information ==
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'''Battery Testing''' - We charged and tested all of our batteries.  We found one bad one that we've removed.  There are four batteries that have been marked for competition, and four for shop testing.  Please do not use the competition batteries for practice.
 
  
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'''Repairs''' - We repaired two of the chargers that had broken wires.  If you are using the chargers please pull on the connectors NOT the cables.  The wires are not strong enough to pull the large Anderson connectors apart.
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There are a lot of details about the electrical system, to make it easy to understand we break the system in to multiple parts: Power, digital in, digital out, analog in, solenoids, and other.
  
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'''New cables''' - A new camera power cable was created for the robot, allowing Ken to display his solder skills
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== Power ==
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Power is supplied by a 12 volt, sealed lead-acid battery. It sits in a Tuffak box that is closed by a length of 2" velcro that runs around the battery and box.  This means the battery will not come out of the robot even if it's upside down. 
  
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== Week 2 Progress ==
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Power is routed via two Anderson high amperage disconnects through a 120 volt circut breaker to the Power Distribution Panel.  The panel is supplied by FIRST and holds all of the breakers.  Depending on the device we use 40, 30 and 20 amp breakers in the panel.  #6 wire is used for all the main battery connections.  
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The team was not active this week, we are waiting for the chassis to be completed.
 
  
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Parts have been ordered:
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We use three different sizes of wire depending on the device.  Large, #10 wire is used to connect all of the Jaguar motor contols. Each pivot has two motors, drive and steering. There is a Jaguar for each motor.  The large wire has very little resistance and can carry the high current loads of the motors.  
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:10# zip cord wire - we will be using a standard size wire to go from the Power Distribution Unit to all Jaguar / Victor speed controls.  We will see a voltage drop of about 0.1 volts per foot of #10 wire vs 0.2 volts using #12 wire. That is a significant drop in voltage to our robot.
 
  
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:Ring connectors - Breakaway will be a highly "interactive" game, so solid connections is the name of the game. With the "swarf" problem gone on the new Jaguars, we will be using ring terminals for all of our screw head connections. (Swarf are shavings and chippings of metal resulting from metalworking operations. [http://en.wikipedia.org/wiki/Swarf])
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[[media:DEWBOT_VI_Wiring.pdf | '''Wiring information as of 21 Feb''']].  Document contains pictorial view of the wiring, circuit numbers and the amp rating for the breakers.
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:Labels - We are planning to "over label" the robot this year.  Each cable end and each device will have a label that ties back to the overall robot schematic.
 
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== Week 3 Progress ==
 
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Parts have arrived, but the waiting continues.
 
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We did help out our VEX teams with the repair of 3 motors plugs.  It's easy to slip out the remains of a broken pin, strip, crimp and insert a new pin.  3 cents in parts, 5 minutes of time to repair a $20 motor! A big win for everyone!!
 
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== Week 4 Progress ==
 
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Three nights of wiring this week!  First night was putting the Jaguars on the mounting board.  The Tuffak sheets (thanks Arkema) were cut for the cRio and the two sets of Jaguars.  The team took about an hour to mount the components and to create the wire bundles.  The two Jaguar panels will be mounted on the left and right sides of the robot, the cRio panel mounts on the rear.
 
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The second night, Wednesday, was when the boards were installed and the final connections were made to the motors.  Total connection time was less than an hour.  This is a great sign that we can make major repairs on the robot quickly.
 
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On Wednesday we also drove the robot to make sure it could make it over the hump.  While the math and the simulations said it would, there is nothing like seeing cold hard aluminum climb over the hump.
 
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Thursday, the third night, we installed the rotation sensor cables and turned the robot over to programming.  There is some minor work to do before ship, but it can be done while programming has the robot. We should be able to get the following done during the weekend build:
 
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:Install the Tuffak panels for the digital side car and Power Distribution panel
 
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:Install the safety light
 
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:Design, build and install the mounting for the camera
 
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== Week 5 Progress ==
 
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With the snow storms it was hard to get to the robot.  We also are competing with the programming team for access to it.  On Friday the 12th we got the robot from 6PM - 10PM.  During that time we:
 
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* Took everything but the pivot drives off the robot
 
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* Installed / reinstalled all the electrial devices on the Tuffak panels
 
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* Gave the robot to the mechanical team to allow them to weld a new support (and in exchange they welded the safey light bracket for us)
 
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* Reinstalled the panels in the robot
 
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* Reconnected everything (Carly, Scott, Foster and David did this in < 45 minutes!)
 
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* Tested the robot
 
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On Saturday we came up with a super simple camera mounting bracket, another item off the list.
 
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Julie and Cole from the mechanical team did the fabrication of the last two Tuffak panels, so on Sunday we will mount the pressure switch. 
 
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That leaves the posessor motor and the two IR sensors the last three items to connect!
 
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== Week 6 Progress ==
 
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Tuesday 16 February
 
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Solenoids that were mounted yesterday were connected.  The connections are an issue, since the solenoid ends are very sensitive.  Scott made custom cables to go into the cRio.  
 
  
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Saturday 20 February
 
  
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Scott, Foster, David and Siri spent the morning putting the last set of sensors on the board (kicker position, autonomous field position) with Jen doing the cable creation (solder and crimp connectors).
 
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Scott and Jen also fixed some broken wires that were damaged the night before.
 
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Ben R and Foster did the final checkout of the latest sensors and solenoids making sure the cRio can either see all the sensors or move all the components.  We are electrically complete and fully tested! This means we can start [[Glossary#dressing | dressing]] the board in prep for shipping.
 
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== Last Build Daze ==
 
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Sunday 21 February
 
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Robot was [[Glossary#dressed | dressed]] and looks 1000% better than it did on Saturday.
 
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== DEWBOT VI Technical Information ==
 
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[[media:DEWBOT_VI_Wiring.pdf | '''Wiring information as of 21 Feb''']].  Document contains pictorial view of the wiring, circuit numbers and the amp rating for the breakers.
 
  
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== Digital Side Car Reminder ==
 
This is a reminder that the digial sidecar has pull up resistors on all the Digital IO ports.  This means that all the pins report a TRUE even when there is nothing connected.  All switches need to be set up to pull the signal low.  Wires run from ground through the switch to signal.
 
This is a reminder that the digial sidecar has pull up resistors on all the Digital IO ports.  This means that all the pins report a TRUE even when there is nothing connected.  All switches need to be set up to pull the signal low.  Wires run from ground through the switch to signal.
  
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[[Category:Robot]][[Category:DEWBOT VI]]
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[[Category:DEWBOT VI]]

Revision as of 22:07, 25 February 2010

While the motors and pneumatics are the muscles of the robot, the wiring is the central nervous system. Electrical wiring supplies power from the battery to the Power Distribution Board, from there to the Jaguar and Victor speed controllers and then on to the motors. Wires also take signals from the sensors to the either the Digital Side Car (for on/off signals) or to the Analog daughter board (position sensors) for processing by the cRio. This page covers the details of the Electrical system, please see [DEWBOT VI Electrical Team] for the build season notes.

DEWBOT VI Technical Information

There are a lot of details about the electrical system, to make it easy to understand we break the system in to multiple parts: Power, digital in, digital out, analog in, solenoids, and other.

Power

Power is supplied by a 12 volt, sealed lead-acid battery. It sits in a Tuffak box that is closed by a length of 2" velcro that runs around the battery and box. This means the battery will not come out of the robot even if it's upside down.

Power is routed via two Anderson high amperage disconnects through a 120 volt circut breaker to the Power Distribution Panel. The panel is supplied by FIRST and holds all of the breakers. Depending on the device we use 40, 30 and 20 amp breakers in the panel. #6 wire is used for all the main battery connections.

We use three different sizes of wire depending on the device. Large, #10 wire is used to connect all of the Jaguar motor contols. Each pivot has two motors, drive and steering. There is a Jaguar for each motor. The large wire has very little resistance and can carry the high current loads of the motors.

Wiring information as of 21 Feb. Document contains pictorial view of the wiring, circuit numbers and the amp rating for the breakers.


Digital Side Car Reminder

This is a reminder that the digial sidecar has pull up resistors on all the Digital IO ports. This means that all the pins report a TRUE even when there is nothing connected. All switches need to be set up to pull the signal low. Wires run from ground through the switch to signal.

Battery Care and Handling

Lead-Acid batteries (like the ones used by FRC) do not like deep discharge (10.5 Volts is deep discharge). This causes the chemistry in the battery to "wear out", leaving the battery weaker and eventually unable to take a charge. So, change your batteries often, don't stress them so much.

They also very much do not like staying even a little discharged for any length of time. A week at 50% discharge will cause measurable damage. So, recharge the batteries immediately after every use. (An unused battery can sit 2 to 3 months without any care, but at that point it MUST be charged up again, or it will be damaged).

Of course, handling them carefully:

  • Lift by the case, never ever by the terminals or attached wires (their ears)
  • Don't drop them - treat the case like it was fragile - it is

Make sure the wires stay firmly attached - a loose connection will suck down all the power (turning it to useless heat) making the robot seem to eat batteries fast.

Engineering Information

Motors

RS555vc Motor Specifications 12 V, 4 500 rev/min free, 0.11 N·m stall, 4.40 A stall, 0.19 A free => 13.29 W max. at 12 V.
RS555sh Motor Specifications

Sensors

Cherry Part CU103602, rotational sensors - used on each pivot to tell what direction it's pointing.

PSOC

PSOC carrier board pin outs This is the board made by e-Stop Electronics to make it easier to make connections.

Electrical

2010 FIRST electronics documentation
Jaguar Information What the lights mean on the Jaguar
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