[FTC]: Losing Control During Competition

[F Elliott]

I suppose this whole issue has been discussed and cussed quite a bit.

We've never had a problem with our robot's Samantha module or controlling it wirelessly. Saturday we lost control of our robot in 3 of 5 matches. Other teams were experiencing the same thing, including one team in the semifinals. In one case, we lost connection to our robot while it was just sitting there doing absolutely nothing. One station on one field seemed to be worse than the others but there was no clear pattern. It happened throughout the day.

Reading the forums I knew this was a problem area. Our Samantha is mounted on its own mast away from everything. It's cabling is stress relieved and tie wrapped. It is powered on its own dedicated feed off the Anderson Powerpole RIGrunner distribution box. We've done everything we can think of. The FIRST representatives looked it all over and agreed we were doing everything they could think of.

We can't get it to fail here at school and we couldn't get it to fail in the pits. We bounced the robot, jiggled cables... everything we could think of. No issue.

We get on the floor, autonomous fires up and then sometime during teleop the blue light goes out and we are dead until it recovers, at which time it usually died again.

Everyone was telling us it was the Samantha module or the field wireless system. It seems to me if the blue light goes out but we still have white, then the problem is between Samantha and the NXT or a power glitch. I'm now wondering if it's a problem with our NXT but I have no way to test that and in any case we can't get it to fail anywhere else.

What are we missing?

[Sasha]

Sorry for suggesting the obvious... but have you checked that the USB cable connecting Samantha to the NXT is fully inserted in the brick and doesn't lose connection when jiggled? we had issues with this ourselves.

[FTC4211]

What programming language are you using on the NXT. Labview or RobotC?

I ask this because I have noticed at the past two qualifiers we have gone to the robots using Labview have had more problems with the FCS dropping them during a match.

[pyroslev]

I presume since you are using The RigRunner that you are using PowerPole Connectors as your main battery connector. If you are still using the Tamiya and the control lost was short, then there in lies your issue. Also, make sure the Samantha is the first device fed off the RigRunner.

If you were to crack open your Samantha Module, you'd find USB port soldered onto the board. You've done well to stress relief the cable but the port is still a weak spot. I'm seeing Model 1 Samanthas starting to break.

Depending the age of the NXT and the use of it, there in lies another issue. Teams that are bringing their NXT up from FLL are likely to see their NXT wear out faster from sheer use. Also too much code the NXT can bog things down, cause lag, etc.

Also, if your NXT's Bluetooth was on, there could the biggest cause of your issue. I've had a team in the Final lose connection with the field cause their bluetooth on the NXT was pinged by someone's phone looking for a Bluetooth connection.

When you got to your NXT after the Match, was the brick locked up? If so there could be the root of the problem. If it wasn't locked up was code still running or had your Teleop program exited? If that has happened and you are using Labview, then you need to look at the laptop you are using to program and upload code. If LabView for both FTC and FRC are on it, then there is another possible cause of the teleop exit. The 2012 and 2013/14 LabView may program the same way but don't necessarily upload the same.

I'm not saying any of the above are the cause but they could be contributing factors. If you have any further questions, feel free to shoot me a message.

[F Elliott]

Great stuff everyone. Thanks for the suggestions.

1. Powerpole connectors from the RIGrunner to the various components but the original DC battery connector (Tamiya?) is still in the mains. It is new and seems stable but that is certainly a possibility. As a rookie I couldn't bring myself to cut these off our two batteries and our charger yet but it's now on the MUST DO list.

2. Control loss was short.

3. We use ROBOTC current release

4. NXT was new this year. No other use than ours for FTC. It's the only one we have.

5. Bluetooth was off. We don't know how to use it anyway LOL I will check this personally since I've been relying on a student for this.

6. I will ask the team about NXT status after we recovered the bot.

7. The FIRST people tried intentionally wiggling the NXT USB connector and couldn't get it to fail.

8. Samantha power last on the RIGrunner. We will change that for regionals.

[pyroslev]

Originally Posted by F Elliott

Great stuff everyone. Thanks for the suggestions.

1. Powerpole connectors from the RIGrunner to the various components but the original DC battery connector (Tamiya?) is still in the mains. It is new and seems stable but that is certainly a possibility. As a rookie I couldn't bring myself to cut these off our two batteries and our charger yet but it's now on the MUST DO list.

2. Control loss was short.

5. I will check this personally since I've been relying on a student for this.

6. I will ask the team about NXT status after we recovered the bot.

7. The FIRST people tried intentionally wiggling the NXT USB connector and couldn't get it to fail.

8. Samantha power last on the RIGrunner. We will change that for regionals.

1&2&8: The most common headache issue I see other than lockup is the Tamiya connector wearing out. That wears out, gets hit and loosens up enough for power to blink out and the radio, no matter it's position on the Rig, to reboot requiring to reconnect. The Alternate Wiring Method for the Samantha is on the FTC site so go look it up.

5. Teams will often turn on the Bluetooth for uploading code or to practice on the field with if the Pit Router is overloaded such that you cannot control your robot on it.

6. Never hurts to check behind the students or have them check behind you.

7. Don't wiggle the USB port on the NXT. That'll wear out the port faster than standard wear & tear. I've seen teams actually use differing types of USB connectors on the NXT to ensure it doesn't move, ranging from specific USB adaptors to taping the cord in.

[skatefriday]

We spent a few months a couple of years back trying
to isolate a short only to find it was the stock battery
connector. Replaced it with powerpoles and the short went
away.

So, yes, powerpoles _everywhere_ are pretty much a mandatory
requirement for reliable operation.

[TheThings5926]

Static can be an issue. I know our team had a lot of issues (4 out of 6 rounds lost communication) at our regional tournament, some of which were static. One of our team members has built a static detector which we have found that our tracks creates a lot of static (we use the tetrix tank treads). We have also found a anti-static solution that you can put on the robot. I am not sure what exactly is in the solution but I can find out.

Best of luck

Matt,

The Things, 5926

[F Elliott]

Skatefriday... We crossed the Rubicon and converted batteries and charger to Anderson Powerpoles on Thursday.

Matt... Thinking about the static electricity issue made me realize

1. We have too much USB cable coiled up in the bottom of our robot. We will get a shorter one from USB Stuff, maybe with right-angle ends for strain relief and put some ferrite chokes on the cable.
http://www.usbstuff.com/cables.html

2. Wonder if the NXT and USB cable's close proximity to one of our drive motors could be causing an induced current noise spike in the cable as the motor is turned off and on.

[cgmv123]

Originally Posted by F Elliott

2. Wonder if the NXT and USB cable's close proximity to one of our drive motors could be causing an induced current noise spike in the cable as the motor is turned off and on.

Motors can definitely interfere with wireless signals. FRC teams are instructed to keep their robot radios away from motors (especially CIMs) and other electronics. Up high and away from metal is a good rule of thumb.

[F Elliott]

Samantha module is high and isolated. However, the NXT and it's USB jack are very close to one of our drive motors.

[skatefriday]

Originally Posted by F Elliott

Skatefriday... We crossed the Rubicon and converted batteries and charger to Anderson Powerpoles on Thursday.

This has the added, ahem, 'downside' that your chargers
can no longer be loaned out at tournaments.

Then again, conversely you can't leach off of another
team's charger.

In hindsight, saving the molex connector and attaching power
poles to it for compatibility purposes and then just packing
that away in your travel kit is probably a good idea.

[Sasha]

Originally Posted by skatefriday

This has the added, ahem, 'downside' that your chargers
can no longer be loaned out at tournaments.

Then again, conversely you can't leach off of another
team's charger.

In fact, a fair fraction of the teams have done the same and equipped their chargers with powerpoles... so you can share with those teams.

[pyroslev]

Originally Posted by TheThings5926

We have also found a anti-static solution that you can put on the robot. I am not sure what exactly is in the solution but I can find out.

If you can, please share it. I'm always looking for something to tell teams to try.

[safiq10]

At the killeen competition this weekend the connection went terribly! during one of my teams matches the teleop drove for 1 second and then went on the fritz for us. While in finals and semi finals our sister team was having their robots going in circles and to prove a point they all put down the controllers too and it was spinning!