[writchie]

Originally Posted by jerry w

actually this is a mechanical solution.
The rule that allows the chain is R05

<R05> Exterior or exposed surfaces on the ROBOT shall not present undue hazards to the team members, event staff or GAME PIECES.

We are not affecting traction as required by R06

<R06> ROBOTs must use ROVER WHEELS (as supplied in the 2009 Kit Of Parts and/or their equivalent as provided by the supplying vendor) to provide traction between the ROBOT and the ARENA....
No other forms of traction devices (wheels, tracks, legs, or other devices intended to provide traction) are permitted.

The chain is a mechanical device fastened to the robot frame and does not violate R41

<R41> All wiring and electrical devices, including all control system components, shall be electrically isolated from the ROBOT frame. The ROBOT frame must not be used to carry electrical current.

By adding a brass chain to the robot frame we have eliminated the buildup of electrical charges. This is a safe and legal method for protecting humans from electrical shock. It also protects the electrical components on the robot.

The rules govern. The Q&A "interpretations" of the rules are official. The "lead inspector" is the final authority at each competition. That is how I understand it.

Re: <R05> this rule is prohibitive - not permissive. It doesn't permit you to install something that would not otherwise be permitted.

Re: <R06> The lack of friction in the discharge "wire" was irrelevant to the Q&A answer. The question presumed the traction was immaterial.

Re: <R41> The Q&A questions was specifically in this context.

IMHO attempts to classify a brass chain, or wire, or metalized string, or whatever as "mechanical" and not "electrical" in order to escape an "electrical" rule are likely to carry zero weight. The actual use of the part makes it electrical, mechanical, pneumatic, or in this case electrostatic.

The referenced Q&A answer prohibits a bleed resistor between electrical ground and the mechanical frame and it prohibits a static wick between mechanical frame and the floor. The meaning of "no , and no" is pretty clear, even in a world where the meaning of "is" may be disputed. The GDC could have answered, yes and yes, no and yes, or yes and no, or even "maybe". Instead they said "At this time, no and no, as these would be violations of Rule <R41>." Since a "static discharge wick" is presently prohibited, IMHO the same would apply to drag chain.

I fully agree with you that a chain (or two) would prevent the electrical buildup. So would a static wick, a wire tail, a foil tail, and perhaps other methods. In fact, your chain idea MAY be the best. I've certainly seen it used successfully in the past. Perhap FIRST installing a drag chain on each trailer (which it controls and could easily supply) and allowing teams to install Static wicks made from off the shelf stranded wire will be the solution.

The GDC has determined that for the time being it wants to maintain floating electrical, mechanical, and surface grounds without electrical connection, although it left this open to later revision. While I am surprised by this ruling (especially regarding wicks), I am sympathetic as are most who have been in similar situations with mysterious ESD issues and a large number of units already in the field. At this stage, I think the GDC is trying to minimize the variables in order to reach the quickest possible solution. We should let them do their job. Perhaps, a couple of fried DS and cRIO's are worth it if it quickly leads to a permanent solution. Maybe with week 2 now completed, they will promulgate a fix and/or rule change that is proven not to cause more harm than good.

Personally, I think there may be multiple problems. One results in a dead Ethernet port on the DS. The other results in a cRIO reset, and sometimes a fried cRIO. Since both are proprietary components, we don't know what protection they have internally - we can only speculate. But since the DS doesn't even have a pull up on the digital inputs, it is likely quite vulnerable. I doubt it has Ferrite Beads and TVS diodes on the Ethernet ports and it is possible that the actual damage comes from induced surges.

IMHO, the best course of action for teams is to have only ESD trained team members handle the Ethernet ports and insure that everything is discharged before plugging things in. I would also recommend that teams be prepared to install static wicks (or chains) if these are ruled as permitted. When operating tethered, I would recommend always using a hub or switch with known ESD protection and only connecting/unconnecting the DS cable in the pits.

As for good news, the forcast for the Florida Regional is 81F/61F with humidity of 40% - 50%. With the return of warm nights, the conditions for static should must less than they have recently been, although Murphy makes sure that ESD can get you anywhere.