FTC Tip #10 – Electro Static Discharge Mitigation

FIRST has been conducting electrostatic discharge (ESD) tests with the new Android-based platform for the past year. In general, the new platform tolerates ESD well. According to our engineering contacts at QTI, the test standard IEC/EN 61000-4-2 outlines the procedure that is used for smartphone ESD testing. Most Android smartphones typically adhere to even higher ESD standards, with the ability to withstand a minimum 10 to 12 kV air discharge, and an 8kV contact discharge. Similarly, the electronic modules that are used with the new platform were also designed to tolerate ESD events.

In our testing over the past year, we have found that the new platform tolerates ESD very well. We have used an electrostatic voltmeter and conducted several driving and Van de Graaff generator tests with various test robots. We have conducted discharge tests where the surface voltage on the frame of our robot (as measured with our voltmeter, which has a limit of 25kV) exceeds 25kV without any disruption to the robot. However, we have received credible reports from the field and have seen in our lab testing that ESD events can disrupt the reliable operation of the robot. In our lab testing, the observed number of suspected incidents is low (on the order of 6% or lower), but we do believe that an ESD could occasionally affect the operation of a robot.

Based on our observations over the past year, the risk that a large ESD event can disrupt a robot is relatively low. However ESD is a regular, naturally occurring phenomena and there are steps that teams can take to help reduce this risk even further:

Static Dissipation
• When Teams arrive at the Field, a member of the drive team should touch the metal frame of their robot to the metal frame of the Field perimeter prior to placing the Robot on the Field.
• Doing this should help dissipate any charge buildup that occurs off of the Field.

Robot Construction/Wiring
• Mounting the electronic components of the robot onto non-conductive substrates (such as a sheet of dry plywood, a piece of PVC Type A, or even a polycarbonate sheet) and using non-conductive fasteners (such as zip ties or nylon bolts and nuts) can help reduce the likelihood that an ESD event will disrupt the robot operation.
• Using shorter runs of cables and wires, and keeping the cables and wires off of the frame of the robot (for example, by routing them through PVC Type A pipes or some other non-conductive conduit) can help.
• Covering or cladding the exterior parts of a robot with a non-conductive material reduces the risk that metal parts of the robot will touch a metallic object on the field and cause an ESD event. Wooden bumpers, cloth/tape and other non-conductive coatings can help.

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