Removable Electronics

[copperhead47]

i created this to get a feel for cool or effective ways to make the entire elecrical setup removable. I saw teams in philly tat had bot pneumatics and electrical removable in one go, it was pretty kool. this year i mounted all electronics on a roughly 1 ft. by 1 ft. plastic panel, and had military spec. circular plugs coming out the front. it worked ok but had to add numerous data adn power wiring and didnt have enough room in the plugs. i am aware of the anderson power connectors which seem very practical, but if anyone has more tips/tricks/ practices that would be greatly appreciated.

[whytheheckme]

I have done modular elec. systems for bots before, so here's what I have to say.

1. Conduit is your friend. If you have many wires going to the same removable component (i.e. an ARM, or a turret), put them in a conduit, with connectors on both ends (so that the whole harness can be removed).

2. Connectors. For data (sensors, low voltage devices, etc.) I like to use DB-9 or DB-15 or DB-25 connectors. Either using ribbon or the regular shielded cable is great. Just keep track of which pin you are using for what. Having connectors on the device, the main board, and on both ends of the harness is helpful. For power (i.e. 12 GA to motors), use SMALL anderson connectors. The big ones are hard to use. If you have more than two wires going the same place in the same conduit, you can use the quick-disconnects that lock together in a row, so that you can have more than two leads on a connector.

[CheesyASCIart]

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[/CheesyASCIart]

The connectors lock together horizontally, so that you can disconnect them all at once.

3. Label your wires. Weather using a multi-colored electrical tape system (i.e. white-red-green) around each end of each cable, or using real wire labels, this is the most important. Nothing is worse than not knowing what a wire is, and taking time to figure it out.

4. Radio. IFI likes to blame radio problems not only on the position of the radio, but the cable. They say that they like a straight run from your FRC Controller to the radio with their 6' Black cable. They say they dont like it wound up tightly anywhere. This makes it difficult for a modular system, where you want to be able to disconnect the main panel easily. The solutions that I have found for this are

4a. Mount your FRC Controller so that the serial ports are on the edge of the board, so that you can plug in your programming cable and radio cable directly without digging into a mess of wires. This is probably IFI preferred.

4b. Run an extention cable (3' or shorter if you can find it (don't make it. At least not for the radio. This is another blame point)) from the port on the FRC Controller to the edge of your board where all of your other disconnects are. Then you can treat it like a different data cable.

5. Make the system usable for someone else. At any point where wires may need to be connected/disconnected to remove your panel, put electrical tape around the connectors AND LABEL THEM (using marker/pen on the tape).

These are just some tips that I have observed while attempting to do this.

Jacob

[AJ R]

Originally Posted by whytheheckme

For power (i.e. 12 GA to motors), use SMALL anderson connectors. The big ones are hard to use. If you have more than two wires going the same place in the same conduit, you can use the quick-disconnects that lock together in a row, so that you can have more than two leads on a connector.

Where do you get these type of connectors that can snap together for mutiple motors?

Thanks

Also, I would recomend, for any electronics system, to keep your wires neat and easy to follow.

[lukevanoort]

Originally Posted by AJ R

Where do you get these type of connectors that can snap together for mutiple motors?

Thanks

Also, I would recomend, for any electronics system, to keep your wires neat and easy to follow.

We got some from here last year. We still haven't used them though, never really had a need for them.

[Cory]

Originally Posted by lukevanoort

We got some from here last year. We still haven't used them though, never really had a need for them.

We used them in 2006 and previous years. Halfway through the 06 season we got sick of them and replaced them with standard terminals. We had nothing but trouble with intermittent contact, no matter how carefully we crimped the lugs onto the wires. They just didn't fit very well into the housings.

I'm sure plenty of teams have used them and not had any problems though, so your mileage may vary.

[whytheheckme]

Originally Posted by Cory

We used them in 2006 and previous years. Halfway through the 06 season we got sick of them and replaced them with standard terminals. We had nothing but trouble with intermittent contact, no matter how carefully we crimped the lugs onto the wires. They just didn't fit very well into the housings.

I'm sure plenty of teams have used them and not had any problems though, so your mileage may vary.

I've used these quite a bit in the past, with only minimal problems. If you don't crimp them right, you will have problems. The ones that were pointed out in an earlier post were the ones I was referring to.


Jacob

[DonRotolo]

1676 had a fully removable electronics board for 2007, I need to find a photo. We won the Motorola quality award at NJ and Buckeye for that. What whytheheckme says is spot on, we used either sub-D connectors or 0.1" headers for the low power connections, and 45 Amp powerpoles for the high power connections, the only exception being the main power & ground which were a big Anderson IIRC.

We gained about a pound in connectors, and maybe 2 pounds of wire (not all of it necessary), but it was worth it when we had to do some maintenance on the banebots trannies - electronics out in 1 minute, back in after 2 minutes.

The connectors were all accessed from the bottom of the robot, while all the equipment was mounted on top. We used a 14" square lexan panel, held down with 2 thumb screws, and lots of wiring channel.

Don

[Pavan Dave]

My Who Am I? is the robot's brain. It is the removable modular controls panel that we mounted ALL of our electronics out on. It was very efficient and was very good in terms of shape weight et cetera. We used a variety of different connectors to mount sensors (15-30 pin connectors) and our speed controllers to our motors (Anderson pins). If you want more pictures I will see if I can take some later.

http://www.chiefdelphi.com/media/img...95d3f216_m.jpg

Pavan.

[copperhead47]

aight- thanks all who replied i learned alot but still need to put it into action in order to understand it fully... ok- i know that the mini-andersons are what to use for the motors but what to use for the data cables?? ive heard d-subs- ive seen cat-5 cables and ive even heard about using sheilded pairs for the cable itself (thats expensive by the way) so i was wondering which is the best combination of hardware. any advice would be great!! see you later

[tseres]

our team didn't do it this year, but we wanted to put all of the electronics on a removeable board. to take them out, we would just unscrew the board from the robot base. for all wires going to places, we were going to use terminal blocks, and we would just have to unscrew them. now, after reading this thread, we could have bought plugs (i'm almost thinking of, like, a 7-pin trailer hitch plug or the likes) that we would just have to unplug. we would need only...maybe 2 or 3? the only things that are off of the board really are the wires going to the motors and sensors....everything else (victors, spikes) are on the board already....

[Alan Anderson]

Originally Posted by copperhead47

...what to use for the data cables?

What do you intend these "data cables" to be connected to at the other end? The size and number of connections will help determine the best connector for the task.

For something like a position-feedback potentiometer, consider a stereo headphone connector. For the CMUcam assembly, you really only need between six and nine wires depending on how paranoid you want to be about power and ground signals, so a DB9 will work fine. If you have a whole bunch of digital inputs (limit switches, quadrature encoders, etc.) you might want to try something like a 15-pin VGA connector.

If you're looking at a whole lot of signals that you want to be able to connect and disconnect easily, Cannon makes a line of products that would work well.

[copperhead47]

i thought about trailer connectors too- but with a 7 pin connector- most likely you would have an unused port left over- good idea though- try looking up "mil-spec" or military specification, or round plugs- the kind i had had 12 contacts for 12-14 guage wire and the other kind- roughly the same diameter had 32 contacts for sensor and data wire- or you could do hwat everyone else here is doin by using mini andersons and D-sub connectors- which isnt a bad idea- theyre all very lightweight and the mini andersons are very customizable. as far as i know i dont know anyone who is using trailer hardware. youre on the right track though

[Lil' Lavery]

116 has used our modular, removable "control box" on 4 different bots at 11 total competitions (developed summer 2004), with only one issue (during a practice match in Peachtree 2006, and it was an issue common to any electrical system). I don't think that 116 will be switching away from the design anytime soon. 2005 Control Box thread
2007 version (before wire runs were cleaned)


The concept is fairly simple, a clear polycarbonate box that can be quickly removed and opened up to be worked on independently from the rest of the bot. We also use the Anderson Power Pole connectors, purchased from Powerwerx in 2007. We have used a different system for connecting the pwm and sensor runs to the exterior of the robot each year, using a DB25 cable in 2007. The 2007 version featured extensions to allow for the reset and program state buttons to be pressed from outside the control box, rather than having to open it up (next to the fan).
Beyond the normal functions of a removable control board, the box also serves to protect and cool the electronics. The large muffin fan creates a wind tunnel effect through the box, keeping all the components at cool working temperatures. The polycarbonate walls shield the electronics from impacts from other robots, game pieces, parts, and falling debris (to an extent), while still allowing for the electronics to be mounted in such a location of easy visibility and accessibility on the field.

[copperhead47]

haveyou experimented with other clear materials other than polycarb? bnecause to my knowledge, poly carb used in liberal amounts is some what heavy although i could be wrong

[copperhead47]

you know?? its funny- i jsut looked at your 2005 design and it jsut hit me- thats what i used as an inspiration for a removable control panel. it doesnt fold up though- its flat plastic panel with plugs out the front- ill see if i can get good pics