[Rookie] How to set up electrical the best way?
 

Hello teams!

We're team 3992, a rookie team from Delray Beach, FL.

I'm posting here because we pretty much have our basic drive train right now, and have electrical components mounted, but I wanted to get a few words in from you since this is my first time doing this.

We have the PDB, 2 jaguars, cRIO, Digital Sidecar, D-Link Router, Battery, and killswitch mounted.

What else should we put on? Is there a "best" or "recommended way to set up the electrical configuration? If you have them, can you recommend or link us to some wiring diagrams or electric set-up guides? What gauge wires should we use, and for which connections? Where can we purchase additional electronic supplies?

Thanks!

Re: [Rookie] How to set up electrical the best way?
 

You would have to use the 12V to 5V transformer for the Router, the signal light, and other misc. stuff.

View the Electric Diagram on the FIRST website.

http://www.usfirst.org/roboticsprogr...rts-electrical

For Data Transfer:

http://www.usfirst.org/roboticsprogr...control-system

Re: [Rookie] How to set up electrical the best way?
 

The Robot Rules specify minimum wire sizes.

You can purchase additional electric parts such as wire and terminals at local stores such as Radio Shack, Ace Hardware, or auto parts stores such as NAPA or CarQuest. You can also find a lot of electronic parts online at places like Digi-Key.

Re: [Rookie] How to set up electrical the best way?
 

What's the purpose of the Rockwell light?
Is that required for a robot? If so, where does it go, and what is its purpose?

Re: [Rookie] How to set up electrical the best way?
 

Put the jaguars in places where absolutely no metal shavings or other debris could get into them! This will ruin them!

In an effort to keep your robots COG low make sure these are as far down as reasonable. Also make sure the battery, main breaker, cRio, and digital side car are easily accessible. Your team will need to get at those fairly regularly throughout the season.

Good luck!

Re: [Rookie] How to set up electrical the best way?
 

The rules specify where it needs to be seen from, don't they? maybe [R57]?They have in past years. It's mainly for the field personnel to tell if your robot is talking to the field system. So it needs to be visible from the front of the robot

Re: [Rookie] How to set up electrical the best way?
 

So the field operators/head ref and others know the state of your robot. It has to be in a visible place where said personnel can see it. It has it's own port on the sidecar, right next to the power input.

Re: [Rookie] How to set up electrical the best way?
 

Yes, it required.
The light should be seen from any side of the robot. - we always try to keep our high on the robot.
This light shows the field team the status of your robot. Either have the light on steady, of how fast/slow the light blinks. Help the field people determine if there is a problem, along with the lights on the router. - which should also be in a higher location to avoid problems. (loss of signal)

Re: [Rookie] How to set up electrical the best way?
 

The rockwell light is so that it is easy to tell your robot is working, it needs to go where it is easly visible. Your main circuit breaker should go where it is easy to get too. R29 lists the wire for the battery, R44 lists the wire gauges for each circuit. In general you should try to minimize the length of the cable, based on the current carry capacity. That is to say your PDB and battery should be very close together and your signal wire can be longer with out causing problems.

Re: [Rookie] How to set up electrical the best way?
 

Do you guys recommend any additional electronic components?

Include motors, but I'm interested to hear what other kind of electronics you've found useful.

Also, in terms of say, adding lights to the robot, is there any rules/regulations, and where/what type of lights can I buy?

Re: [Rookie] How to set up electrical the best way?
 

How about spending some time reading the rules? then you won't have so many questions that are so easy to answer by just referring you to the rules ;)


http://www.usfirst.org/roboticsprogr...ated-documents


.

Re: [Rookie] How to set up electrical the best way?
 

If you want to know about legality and rules, there's this handy dandy thing called the manual. It will contain everything you need to know, favorite it and search for the info you want.

As for electronics, sensors will be your friend; the reason that factories have become more automated is because computer systems operate much, much faster at simple tasks and operations than any human can. Similar reasoning also applies to FRC robots; sensor systems can and will automate basic tasks, like shooting balls and loading them, and also semi-automate (help human operators) in more complex tasks, like driving around and navigating.

Personally, the most useful sensors that can be hooked up are, in no particular order, and I highly recommend you consider using, are:

Motor shaft encoders, for determining rotation speed
Ultrasonic sensors, for medium-range object detection
IR sensors, for close-range object detection
Limit switches, for close-range object detection
The accelerometer/gyro KoP combination, for tilt and speed referencing (making sure there aren't bad readings)
Camera imaging (many uses)

One possibility that I've considered but never used is a current sensor, which is mainly as a fail safe for small, easily destroyed motors.

Re: [Rookie] How to set up electrical the best way?
 

Minor point of order: it is not a transformer. It's a DC to DC converter.

Re: [Rookie] How to set up electrical the best way?
 

K,
This is a time that I must suggest you contact a veteran team in your area for a couple of hours of discussion. There are a lot of documents on line both here and on the First site that can help. Please look for my electrical presentation. While somewhat dated, most of it is accurate. For my money, here is a list of do's.
1. Mount the PD and battery close to the center of gravity on your robot and make sure they won't fall off when your robot turns over. You can't run if the battery is laying on the floor. Insulate your battery terminals ASAP and keep them insulated at all time. The fully charged battery can supply over 500 amps. That is enough to weld metal, melt tools, and cause sparks.
2. Mount the PD and battery in the center of your electrical loads/speed controllers, this helps with losses and keeps wiring short.
3. Mount the 120 Amp breaker close the PD and battery but in a position where it is easily accessible to someone who has never seen your robot and who is trying to keep your robot from setting itself on fire.
4. Keep power wiring short! Yep, I think it's that important to mention twice. Data, PWM, CAN bus, sensor and pneumatic solenoid wiring can all be long without any bad effects. Power wiring is a different story.
5. Make sure your Crio is electrically isolated from the chassis.
6. Make sure you supply power to all analog and digital sidecars and that you include the +5 volt regulator connected to the marked 12 volt supply connector a the end of the PD. This regulator will feed your wireless gaming adapter.
7. Be sure to wire the Crio to the dedicated +24 output on the end of the PD.
8. Make sure you do not have any whiskers sticking out of your connectors, anywhere on the robot and insulate all connections.
9. If you use crimp connectors, use the "tug test" to insure all crimps are properly made. Grasp the terminal in one hand and the wire it is attached to in the other and tug like crazy. If the connector pulls off the wire, replace it and try again. Loose connectors fail and heat up.
10. Use the color code and wire size minimums listed in the robot rules. Using small wire with small breakers won't allow the performance from motors that you expect. CIM motors draw 133 amps when stalled. If you use #18 wire and 20 amp breakers smoke will result.


And as a PS, read the manual, three times at least today. Then reread a couple of more times and then be aware that Team Updates are published every Tuesday and Friday which will modify the manual. Those changes will initiate a manual revision. Last year we were at Revision K at the Champs.

Re: [Rookie] How to set up electrical the best way?
 

Lots of good advice already given. In addition, try to find someone who is experience in wiring, preferably machine wiring. There are so many things to know about wiring such as tight connections, neat wiring secured and away from sharp edges and moving parts. In just two years of FIRST I have seen many robots fail through little wiring failures.

Re: [Rookie] How to set up electrical the best way?
 

Zip ties do a good job of keeping masses of wiring neat, and can be easily cut away if needed.

Also labeling speed controllers and fuses helps. Especially with CAN when the jaguars have addresses.

Example of one of the boards i did that initially wasn't great, but zip ties made it much neater and easier to follow wires:

http://www.vandenrobotics.com/plogge...n/sn850239.JPG

Re: [Rookie] How to set up electrical the best way?
 

I'd recommend adding corresponding letter or number labels on the end of each wire, then a wiring list describing the gauge of each wire, it's source and destination, as well as its function. A wiring list takes a bit of time to set up, but is hugely beneficial for quick fixes. It eliminates the need to trace a wire through webs and nests that will almost certainly build up on your robot.

Re: [Rookie] How to set up electrical the best way?
 

Keep in mind that this board is missing a circuit breaker, which you must have (you seem to be referring to it as the "killswitch").

Other things that you may want to take a look at are spiral wrap and the plastic routing chain that comes in the igus bag. They're both handy ways of protecting long wire runs, and in the case of the latter, ensuring a constant direction of motion for said wire run as you actuate an appendage.

Re: [Rookie] How to set up electrical the best way?
 

Thanks for mentioning that, i forgot ours was elsewhere on the robot that year.

You may someday decide to make your electronics removable like that panel, in which case certain crimps make it easier to remove and replace quickly like these anderson connectors. (also pictured in the left corner of the electronics panel i posted)
http://www.powerwerx.com/anderson-po...owerpole-sets/

Re: [Rookie] How to set up electrical the best way?
 

Steven,
A very pretty wiring job! Congrats.

Re: [Rookie] How to set up electrical the best way?
 

Here is our software development bot. It is in a smaller footprint than the competition robot so it is less intimating when testing software. We are trying Jaguars for the first time and we made a backbone CAN bus (not daisy chain so it won't have the problem of one Jag dies, all down stream jags will fail) using RJ-12 connectors. The bus is pretty much two twisted-pair wires punchdown to 4 RJ-12 connectors. Also notice the Anderson connectors for motor power and RJ-11 connectors for the encoders. So unplugging all motor power and encoder cables will allow us to separate the electronics from the frame cleanly.

Re: [Rookie] How to set up electrical the best way?
 

what is the white box on the right onthis picture? http://www.chiefdelphi.com/forums/at...6&d=1326270641

sorry im just gonna assume that was a silly question. haha thanks

Re: [Rookie] How to set up electrical the best way?
 

Looks like a CAN device. If you're driving the Jaguars with PWM, you don't need to worry about it.

Re: [Rookie] How to set up electrical the best way?
 

It appears to be a CAN hub of some sort. Instead of wiring from Jaguar to Jaguar as is expected, I think that robot has the CAN connections going from each Jaguar to a central, likely custom-built, box.

Re: [Rookie] How to set up electrical the best way?
 

Yes, that's a CAN bus backbone. All Jaguars are running as a T-tap to the CAN bus backbone. So there is no issue of daisy chaining where one segment has problem and all down stream Jags are disabled. The box is just an RJ connector plate with 4 RJ-11 connectors. Two pairs of twisted wires form the backbone of the CAN bus. One power pair, one CAN-H CAN-L pair. The wire pairs are routed around each connectors with a punch-down tool. Very reliable. At the end of the CAN-H, CAN-L pair is a terminating 100-ohm resistor. The other end of the pairs is terminated to a RJ-11 male connector and plugged into the 2CAN.

Re: [Rookie] How to set up electrical the best way?
 

I have a question about the Anderson Connectors....Do you use 30 A connectors and 45 A connectors (depending on the breaker) or just stick with 45A connectors for everything? It looks like the size of the housing doesn't change.

Re: [Rookie] How to set up electrical the best way?
 

Do you have pictures of the inside of the box, I'm not quite sure I have a clear picture of what's going on inside. This seems like a great way to eliminate one of the problems with CAN.

Re: [Rookie] How to set up electrical the best way?
 

I am making a 12-port CAN backbone tonight. I will take some pictures to post.

Re: [Rookie] How to set up electrical the best way?
 

We use the 45 amp connectors exclusively.

Re: [Rookie] How to set up electrical the best way?
 

We use the size that is appropriate for the wire. You can have difficulty getting a good crimp if your wire is too small for the connector! You are correct, the housing size is the same, although you can get it in many different colors to help keep your robot organized!

Re: [Rookie] How to set up electrical the best way?
 

Here are the pictures of the 12-port CAN hub (part 1 of 2).

Re: [Rookie] How to set up electrical the best way?
 

Part 2 of 2.

Re: [Rookie] How to set up electrical the best way?
 

Thanks for the pictures, that doesn't look to complicated. Are any of the parts special or just normal RJ11 stuff?

Re: [Rookie] How to set up electrical the best way?
 

Those are just normal RJ-11 stuff I got from Home Depot.

Re: [Rookie] How to set up electrical the best way?
 

One thing I heard of to keep things organized is to mount everything on pegboard. I am going to try that this year.

Another thing to keep cables organized is to use a strip of electrical tape every six inches to hold each pair of wires together. For example, it makes sure that you know the positive and negative wires are going to a specific motor.

Re: [Rookie] How to set up electrical the best way?
 

Perf stock aluminum is easier to use and can be cut with a pair of shears.

Re: [Rookie] How to set up electrical the best way?
 

Andy Mark perforated polycarbonate board is great. The holes line up with most FRC parts. www.andymark.com/product-p/am-0836.htm

Re: [Rookie] How to set up electrical the best way?
 

But it's not electrically isolated like a peg board would be :)

Re: [Rookie] How to set up electrical the best way?
 

We have had good luck with 1/4" Lexan. Easy to drill and tap and pretty strong.

Re: [Rookie] How to set up electrical the best way?
 

Everything has a drawback. We have used perf for as far back as I can remember.

Re: [Rookie] How to set up electrical the best way?
 

Garolite can be great for mounting electronics. It's very resistant to heat, chemicals, and electricity. It's also very strong.

It has a lot of the properties of carbon fiber, but is much cheaper.

Re: [Rookie] How to set up electrical the best way?
 

Mike,
I like that. If we ever go to a can bus can I copy it?

Re: [Rookie] How to set up electrical the best way?
 

Are you referring to my CAN bus hub? If so, sure. You are welcome to it. There are too many discussions in this thread :) I am very new to CAN bus. So the design is not proven. Our test bot runs fine with the 4-port hub. My limited knowledge on transmission line tells me it shouldn't have any issues with wave reflection.

Re: [Rookie] How to set up electrical the best way?
 

Just so you know... If a jaguar in a daisy chain fails, down stream jags are NOT affected. The contacts on the PCB are wired through (in to out) without going through active components.

The only exception to the rule is in the case where you are using the Jaguar as an RS232 to CAN bridge... Since that jaguar is actively translating commands, if it fails, the link fails. But again, any other Jag in the chain can lose power and everything will keep operating as it should.

Test it out for yourself - we did.

Re: [Rookie] How to set up electrical the best way?
 

Just out of curiosity, how exactly did you conduct this test?

When experimenting with CAN last year, we ran into a Jaguar that terminated the network when the chain reached it (but we've had far more than our share of bizarre Jaguar phenomena).

Re: [Rookie] How to set up electrical the best way?
 

We pulled breakers out of the PD board. on jags through the line while maintaining comms with the Jags along the chain.

The schematic for the tan Jag is available online (to substantiate my claim): http://www.ti.com/lit/ug/spmu022c/spmu022c.pdf see page 42 upper right hand corner.


Could the problem you saw have to do with wiring?

Re: [Rookie] How to set up electrical the best way?
 

Oh, I see. I was wondering if you had taken an actual failed Jaguar (i.e. one that wasn't functional) to see if it would facilitate a network connection.

The problem we had wasn't due to wiring (confirmed by swapping wires between connections to confirm functionality), but more likely due to internal Jaguar complications (which seem to pervade all our attempts to coax them into being functional).

In any case, I would believe that the rationale behind a backbone would be that it would allow one's CAN to continue functioning even in the event of a bizarre Jaguar breakdown in which the hardwired connection is somehow shorted or cut.

Re: [Rookie] How to set up electrical the best way?
 

Our team ran the entire season last year using CAN without a single wiring or programming issue. We made the cables once and forgot about it. We went to two regionals and 3 off season events. The robot was driven all summer for driver training, brought to demos for fund raising, and is being used now to demo code and test functions for the 2012 games. And everything's still working, and everything's over CAN. I personally can't say the same for any of our robots PWM cables in the past.

To me, the backbone element gets rid of my favorite feature of CAN, clean simple wiring. And I don't think I quite understand the rational that it would help resolve shorts/cut of your communications cables. I would think this system is still susceptible to shorts, and if a wire is getting cut during a match, then me or my electrical team made a grave mistake in how we ran the wires...

That said, the wiring in that backbone box is really clean. If that's the route a team wants to go it looks like a nice reliable solution.

Re: [Rookie] How to set up electrical the best way?
 

Based on a smattering of reports from a couple of teams, that Jaguar might just have had a connector with the pins not sprung out far enough to make good contact with the CAN cable.

Re: [Rookie] How to set up electrical the best way?
 

The hardwired connection I was referring to was the internal Jaguar connection; i.e. daisy-chaining is susceptible to internal Jaguar complications, whereas a backbone is less so (only the Jaguar on that branch will be affected). Sorry if that wasn't clear.

@Alan, thanks for that info - I hadn't been aware that that had been an issue. I'll keep that in mind when we play with Jaguars in the future.

Re: [Rookie] How to set up electrical the best way?
 

Yes, that's true. I realize my mistake after I post. That's why in my subsequent post I said the following instead.
If you make your own CAN bus cable, which I do, you may have cable problem or connector problems that would affect down stream Jaguars.

Re: [Rookie] How to set up electrical the best way?
 

Sorry that I'm late to the party, I found my way here by a link from a different thread.

I'm curious how the CAN hub is holding up during testing. It is an interesting tradeoff between cable reliability and signal reflection. How many places are you terminating? What are your cable lengths?

If I remember my CAN math correctly (and honestly it has been >2 years since I've done any form of line reflection analysis), at 1 megabit those taps should be limited to a third of a meter. But I think that was assuming an electrically significant distance between the taps.

Could you scope the bus and see what the reflections look like? If it works, this could be really handy.

PS: Maybe this needs to be spun out into a different thread.

Re: [Rookie] How to set up electrical the best way?
 

I have spun off a different thread.
http://chiefdelphi.com/forums/showth...15#post1121115