Quote:
Originally Posted by Greg McKaskle
That leaves us with the comparison of estop and disable. What is the difference and why.
One goal was for teams to become familiar with estop before they show up to a field -- to know it exists, perhaps use it a few times and understand that it doesn't just disable the bot. If you use it on the field, you are done.
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So then next question is why does the field require this? 10 years ago, it didn't.
Between the e-stop keeping you from finishing the match and rules that make people afraid of getting red-carded, the e-stop doesn't get used as much as it should in matches. For example, one year we were having trouble with our autonomous and occasionally we would run into the wall at full speed. We were fine after autonomous and could continue the match. After the second time, the refs warned us that we would get a red card if it happened again. Since it didn't happen very often, we didn't want to disable the autonomous. Because of this, we decided that we would hope that it wouldn't happen again, but if it did, we'd take the red card. A much more ideal case would have been for us to be able to hit the e-stop before the robot hit the wall, and un-estop after autonomous was over. This would have been safer for both the field and the robot. I've seen many other similar cases too, for example the robot last year (logomotion) that shot straight backwards in autonomous and hit the opponents.
I think, on the field, there are many more uses for an e-stop that is possible to undo then for the current setup.
Quote:
Originally Posted by Greg McKaskle
Another goal was to encourage an inspection. You didn't just disable the robot, something caused you ESTOP the robot. Perhaps you should do an inspection for cause or for damage before compounding the issue. If you meant to disable but estopped instead, it is a small pain. If something about the robot's behavior truly deserved an estop reaction, you don't want to repeat that, right? Something probably needs to change. Similarly, an estop in an industrial setting would typically have a reset procedure different from an operator disable.
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A piece of industrial equipment would also do something something additional, such as shut off power. Since that isn't possible, any difference between disable and e-stop is contrived.
The process described sounds like lockout / tagout, where a piece of equipment is turned off and locked in the off position with an identifying tag of the person doing maintenance. For the robot, this could be implemented by using a 'big' key for disable, and a second key to e-stop, after the robot has been disabled. This provides the same level of safety with much higher convenience.
Quote:
Originally Posted by Greg McKaskle
I've observed that many will power cycle the entire robot, and that is fine, but it does take longer. The minimum needed to clear an estop is to hit the physical reset button on the cRIO -- a toothpick works nicely. This leaves the radio powered and your road to learning the difference between estop and disable is a bit shorter.
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I know in our case, the power button is more easily accessible and doesn't require special equipment to reach, so it ends up being easier. Of course, the reboot robot on the DS is even easier, but it's disabled when e-stopped.