Re: VEX Interference at Hub Competition
- In the real world we would have scrapped the VEXnet system. We had connection problems in our lab where there are six strong wifi signals in the 2 GHz range. The problems disappeared when we went to an area with fewer or weaker signals. Our "company" wouldn't do business with someone that can't provide the service promised.
The students were great at trying to solve the problem. BEST and VEX need to do the same.
--- In email@example.com, Lori Jack <mail4jacks@...> wrote:
> I will only remark on your last paragraph. Definitely a great competition.
> It's all about the real world and working through problems is part of life
> On Sun, Oct 16, 2011 at 10:56 AM, seancsnm <sean@...> wrote:
> > **
> > Your problem has been interesting, though very unfortunate. I say
> > interesting because last year, we had very occasional problems with
> > connections using the VEX system, to where we we never needed to pursue a
> > solution. This year, however, ever since we've gotten a working robot two
> > weeks ago, we've had constant issues with the robot disconnecting from the
> > joystick. Sometimes it would reconnect, others it wouldn't. Through the
> > troubleshooting process, we replaced a suspected faulty USB dongle (which
> > disconnected every time it was tapped), a joystick (which ceased to connect
> > to the computer after repetitively trying to update the firmware), a battery
> > (which we thought had a bad connector), and finally a battery
> > adapter/connector (which we finally discovered was causing problems, as the
> > wire slipped right out while replacing the battery).
> > Although we haven't had time to test to see whether the connector was the
> > problem, I do know that we were still experiencing disconnection problems
> > with a different battery connector, different battery, different USB dongle,
> > and different joystick. Finally, at mall day yesterday one of the officials
> > brought to our attention the fact that the USB dongle is very sensitive, and
> > being so close to the Cortex where all of the current is being drawn from
> > disrupts the signal, causing it to randomly disconnect while driving. This
> > year's Cortex's apparently have raised USB plugs to try to eliminate the
> > issue, but we have an old one. He suggested shielding the dongle by wrapping
> > aluminum foil or some other shield around the underside (but not the top) of
> > the USB dongle. The official BEST solution is apparently using the USB
> > extension cable to move the USB dongle away from the Cortex. It is also
> > important to make sure it is away from motors (and probably wires) too,
> > because motors have a strong electromagnetic field that could easily disrupt
> > the USB dongle. After hearing about this, we used the adapter to mount the
> > key on our arm; the furthest from the electronics it could get.
> > Although the VEX system has brought some good advantages, it has had a lot
> > of inherent problems, which take a ton of time to work around. The past two
> > years our largest problem hasn't been a design that can't score, but rather
> > working around VEX-related issues. For example, last year we burnt out a
> > Cortex and caused multiple servos to strip by doing the same thing we'd done
> > in past years. Thankfully, VEX has worked with BEST to solve these issues,
> > and continues to do so. The BEST competition tends to be very hard on
> > returnable components, much more so than the VEX Robotics Competition. I
> > don't think VEX quite had a handle on what they were getting into when they
> > designed components for the BEST competition.
> > As a senior, I think the competition has been completely worth it every
> > year since I joined 6 years ago. Although things have changed a lot, it is
> > still a great learning experience, with many challenges.
> > --- In firstname.lastname@example.org, "ripphyzard" <srippetoe@> wrote:
> > >
> > > So today was the second most frustrating day of BEST I have experienced
> > in the past ten years. Every round had robots not running because the VEX
> > joystick lost comm with the Cortex controller, except for one preliminary
> > round. We had comm in our first semifinal round and half of our second. We
> > only had comm for one minute in the three rounds of the finals. We only had
> > six out of fourteen rounds with radio comm for the entire round. To my
> > knowledge, every team experienced similar issues, though we had our worst
> > problems after the preliminary rounds.
> > >
> > > Another team went through all three semifinal rounds without ever having
> > radio comm. Yet another missed a round of the finals because of the lack of
> > radio comm. Some rounds only had one of four robots running, all the result
> > of the radio systems not linking.
> > >
> > > After we were finished today, I just could not imagine spending six weeks
> > next year working with the kids to put a robot together to go through a
> > similar experience. VEX and BEST need to find a solution. The communication
> > problems are well documented on the VEX forums.
> > >
> > > There is an upside to this disaster. At dinner this evening the team told
> > me how much they enjoyed the past six weeks.
> > >
> Lori Jack
> *""To get the right word in the right place is a rare achievement." ~Mark
- I turns out that the problems at the North Houston BEST competition were caused by the host school's wireless controller system. It prevented ad-hoc networks from connecting. We and many of the other teams were aware of items 1, 2, and 4 below but that didn't help. As to item 3, I can see how that could be a problem, but I would expect to see more teams establish a connection then lose it during the round. Nearly all teams just could not get a connection to start with.
--- In email@example.com, "Maier, Steven" <sjmaier@...> wrote:
> Our Game Day was Oct. 29th. I do not know of any WiFi interference experienced among teams during our competition, despite there being several WiFi networks available at the venue. Here is what I recommend if you are experiencing problems:
> 1. If you upgrade the firmware on the microprocessor controller, make sure you also upgrade the firmware on handheld controller. Sometimes it takes several attempts.
> 2. Tether the units after upgrading firmware.
> 3. Place a piece of folded cardstock paper (or Velcro or duct/electrical tape) underneath the USB key as you slide it in to the microprocessor controller to assure a snug fit. The optional thumbscrew takes care of this on the handheld controller. If using Velcro or tape, just make sure the adhesive side is not in contact with the returnable kit parts.
> 4. When powering up the controllers, make sure the units are very close and wait until they are properly synchronized for a few seconds before allowing any distance between them.
> I believe connection issues experienced at some hubs are most likely a combination of
> * loose USB keys (definite source of communication problems)
> * not waiting long enough for the controllers to synchronize at power up (definite source of communication problems)
> * an upgraded microprocessor controller but not an upgraded handheld controller (may or may not be relevant-I don't have direct evidence of this creating a problem, it's just a hunch)
> Like I said, we didn't really have connection/interference problems. But during the team meeting before competition began, I strongly emphasized items 3 and 4 above.
> Steve Maier
> HL BEST
> Kit Committee Chair
> From: firstname.lastname@example.org [mailto:email@example.com] On Behalf Of ripphyzard
> Sent: Tuesday, October 18, 2011 1:50 PM
> To: firstname.lastname@example.org
> Subject: [bestinc] Re: VEX Interference at Hub Competition
> I made the following suggestions to Dr. George Banks, the executive director of BEST, and Ken Berry, the regional director for Texas BEST.
> * Have each team check for VEXnet communication problems when they check in the robot
> * Only allow teams to use their VEXnet USB keys when they are on the competition field
> * Have the wireless routers at the competition venue disabled
> * Ask everyone in the venue to turn their wireless devices to airplane mode
> * Do something for teams that cannot connect besides say "I'm sorry"
> I recommend that any team that has not competed yet should do their own thorough check to make sure they have wireless connectivity with their robot when they arrive at their competition venue, be it the night before during machine checkin or the morning of the competition. The week before would be even better because you might have a chance of getting the wireless in the building turned off if it is the cause of the problem.
> You really don't want to experience what we did during our hub competition.
> --- In email@example.com, "ripphyzard" <srippetoe@> wrote:
> > So today was the second most frustrating day of BEST I have experienced in the past ten years. Every round had robots not running because the VEX joystick lost comm with the Cortex controller, except for one preliminary round. We had comm in our first semifinal round and half of our second. We only had comm for one minute in the three rounds of the finals. We only had six out of fourteen rounds with radio comm for the entire round. To my knowledge, every team experienced similar issues, though we had our worst problems after the preliminary rounds.
> > Another team went through all three semifinal rounds without ever having radio comm. Yet another missed a round of the finals because of the lack of radio comm. Some rounds only had one of four robots running, all the result of the radio systems not linking.
> > After we were finished today, I just could not imagine spending six weeks next year working with the kids to put a robot together to go through a similar experience. VEX and BEST need to find a solution. The communication problems are well documented on the VEX forums.
> > There is an upside to this disaster. At dinner this evening the team told me how much they enjoyed the past six weeks.