Re: [FTC]: Playing Forensic Roboticist.
 

I have done lots of testing with RobotC on two NXT's, I haven't had any problems yet. Although at the competition I had this happen to me, my alliance partners and opposing alliances many many times. This needs to be solved. Hopefully before the championship as it's probably the most backlogged tournament already.

Re: [FTC]: Playing Forensic Roboticist.
 

I've barely been able to recreate what actually happened to us at the tournament -- basically at the Ontario FTC Championship, we saw our robot keep moving, even though we had lost all joystick control.

We've been at this for the past week, so this is the first time that we actually saw it happen again.

On the screen of the NXT, it shows that the bluetooth was disconnected (the diamond beside the bluetooth symbol became a less than sign), but the teleop program was still running. The motors were still doing the last thing we told it to do before the bluetooth connection got lost -- AND THE ROBOT DID NOT SHUT DOWN THE MOTORS after the connection was lost.
The NXT screen was still showing "Teleop RUNNING"

I don't know if we can recreate this problem again or not as it was the first time we saw it in the past week of testing and practicing. The FMS showed that the robot was still connected on bluetooth.

This is a brand new NXT (out of an unopened box as we had replaced the original NXT thinking it might have been flaky), Robot C 1.46 with the latest firmware, running the competition templates.

Re: [FTC]: Playing Forensic Roboticist.
 

This happened to pretty much every team at least once at the Ontario regional (IIRC). Specifically HiTechnic needs to work on this...

Re: [FTC]: Playing Forensic Roboticist.
 

Not sure if this is a HiTechnic problem or not. The NXT was still running the Competition template code when it lost the bluetooth connection -- shouldn't that have stopped the robot by terminating the teleop program? That's what I would have coded for safety (i.e. an out of control robot still running in teleop... think of the burned out motors, let alone the refs running away! -- remember, the NXT will never know when to stop as the bluetooth link disappeared)

Re: [FTC]: Playing Forensic Roboticist.
 

How is "move a specified distance" implemented in robotc?

In labview, the vi disables the MC's 2.5 sec timeout and then issues a "run to position" command to the MC. LV then sits in a blocked loop waiting for a "done" from the MC. LV uses it's own 10 second timer to abort if the target is not reached.

This strategy has many downsides: the NXT will not respond to a disable, and even if the program is halted, the MC will continue to run until it reaches it's target.

You need a sepparete loop checking enable status to be able to break the motion.

As for the "connected status", this must have a longish timeout. I can turn off my NXT and the status shows Connected until I turn it back on again.

Re: [FTC]: Playing Forensic Roboticist.
 

We are using NXT-G for our programming and have only had 2 issues. Not sure if #1 is related to memory loss (or whatever it may be) but sounded similar to your experience.

1. We had an extremely long wait from when we connected to the FMS to when the actual match started. Our robot did absolutely nothing. In matches after that, if we had a long wait we would stop our autonomous program and restart it. It seemed to work. We never had that problem again.

2. In the middle of a match one of the controllers stopped working. It was controlling the 4 12v-DC motors. The other controller worked fine controlling our NXT motors and servos.

Re: [FTC]: Playing Forensic Roboticist.
 

yeah in the ontario regionals alot of stuff like that happened.

also in one of our matches, we didn't loose COMPLETE joystick controls, but it somehow seemed VERY offset. i'm pretty sure we still had control because i do recall the button we coded for 100% forward still works. but the joysticks seem to be offset, and the robot itself started moving backward and knocked our teammates off the ramp. but with alot of luck we managed to score 2 pucks into the high goal and won the match lol.

the thing is though, i think we wiggled the joystick before the teleop mode, so maybe when it looked for center, it ain't rly center. (i really don't know how to explain this).... so from then on, we wait until at least one of the other robots to move before us moving.

Re: [FTC]: Playing Forensic Roboticist.
 

Regarding the "memory leak" problem.

The LabVIEW / NXT-G firmware can do a lot of dynamic memory allocation that will eventually cause garbage collection (GC) of memory. It may be that GC is not always robust and you're getting the spurious program aborts because of a failed GC command.

Simple blocks like adding two integer variables will not do nemory allocation. But blocks like concatenating a string, display on LCD, etc will. I also think the "get last joystick message from FMS" likely involves a menory allocation.

ROBOTC uses different firmware that is not performing extensive memory allocation.

Re: [FTC]: Playing Forensic Roboticist.
 

The "File Error" message is a general catch all message and could include memory leaks or other things that cause an abnormal user program exit.

ROBOTC does not use a single error code and has about 50 unique exception messages that it checks for.

Just thinking about this, in NXT-G, displaying text on the LCD screen performs memory allocation and free for the strings involved. So depending on how frequently the screen is updated, there could be a lot of memory allocation for a robot sitting idle.

Re: [FTC]: Playing Forensic Roboticist.
 

We found that when you connect the joysticks to the USB, whatever position the analog controls are at the time power is connected is considered to be zero. (Unfortunately we had that confirmed in round 5 in Atlanta.) This zero setting appears internal to the joystics themselves, so there's no apparent way to correct for this in software that we could find.

If (as in our case) one of the joysticks is sitting on the other and the analog control is initialized uncentered, the only way to clear that is to unplug them, wait a moment, replug, and re-scan for the joysticks.