It will be made for the kit chassis. Even a version that has the front cut out. We can't adapt It that well for everyone but most people who don't have a safe system in place are probably teams using the most chassis.

Re: Safety Issue: Robots Moving in Pits
 

Consider making a robot 'playpen' instead. A plywood sheet covered in carpet with a rigid barrier around the edge. Robot drives on carpet, works with any chassis, robot can't drive away, no blocks to tip over...

Re: Safety Issue: Robots Moving in Pits
 

I am not at all objecting to this idea, and more power to you for taking this initiative that you see as useful.

That said, most of this thread is about how smart and well-meaning safety devices and procedures (pulling breakers, disabling code) can be improperly/ineffectively implemented without something at we're calling "common sense" and/or "safety culture". Depending on your team and robot, it may be more likely that you'll disable code incorrectly, or that you'll disconnect electronics incorrectly. Or that you'll use the mechanical wheels-up method incorrectly. Have you ever seen a robot change CG quickly or contact something with its manipulator such that its wheel contact the blocks? I have. What about someone or something knocking into it that could cause the wheels to contact a surface?

Is the mechanical solution better than the programming or electrical solution? In general? Maybe. For a specific team? Who knows; I don't. Feel free to argue that it's better, but I don't see how you can argue that it's foolproof. Maybe you can personally make a rig that is foolproof (I raise you a better fool) by sizing it correctly/etc, but it'll be just as specific if not more so than pulling a breaker. Every solution has its problems; ignoring them seems to me personally to be hypocritical.

Re: Safety Issue: Robots Moving in Pits
 

A software glitch is another reason to keep a clear kill zone around the robot when testing, regardless of where the testing is being done. Jim's recommendations that people be warned to be vigilant are another "must do". How many of you have seen a change made to one part of the code and an unrelated part of the code gets screwed up? Just because you "only changed the code controlling the LED underglow" does not mean other actuators or motors might not start moving. While pulling the breakers can prevent an accident, you will still have to test with the complete system with the breakers installed because you will be unable to detect the fault if the breakers are pulled.

Re: Safety Issue: Robots Moving in Pits
 

On the initial point, the thread is about robots driving in the pit. If we try to have any broader of a discussion this won't yield any result. All of FRC safety is to big for one thread.

"Lack of basic integration between hardware and software to ensure basic functionality works as-designed" and "Unchecked electrical modifications by a rookie student - really, teams do this?" Yes I'm pretty sure it has/will happen. You do realize this is FRC right?

In fact very early in our 2014 build this (variation on elc scenario) happened with a couple of our rookies. Just as the drive base was done I instructed them to use their own knowledge and reading skills to figure out how to wire it. The point was to not have me/mentors hover over them when we don't need to and let them learn from any mistakes. So after they were done we placed the drive base on blocks, place the battery in, check main breaker, plug in battery, and flip main breaker. And the robot goes nowhere as the left side drive spins in mid air. I knew it would happen but I was sill able to let them see it and understand how that kind of mistake would affect them in less controlled environments. If we were at a competition at that knowledge level they wouldn't have looked at a victor 888 so long as I was around or even alive.

My elc scenario example assumes 1. lack of a more experienced person to check 2. competition stress and fatigue 3. added stress of a critical failure 4. an immediate time crunch. 5. no blocks. So yes I can see how something similar can happen.

Edit: Just as I post this and go to the top of the page I see this in the spotlight section: I always say find what works best for your team, for your given situation. Why should we rely on someone else to tell me what will work best for our situation? - JVN

So I'll take that as a sign to quit arguing.

Re: Safety Issue: Robots Moving in Pits
 

Not a bad idea.

Re: Safety Issue: Robots Moving in Pits
 

How would this fit in the pit? Would it just be the same size as the robot? Would it be in the pit all the time? I ask because I can't visualize a 10x10 space fitting toolboxes, fenced off playpen, and crew members coming in and out on a regular basis.

I think I should also clarify that when I have mentioned "blocks", I was implying blocks that were securely fastened to a cart or a table or whatever the team uses to work on the robot. Obviously just laying blocks on the ground with a robot on top doesn't prevent someone from bumping the robot and then causing the blocks to fall.

Re: Safety Issue: Robots Moving in Pits
 

Precisely (part of) my point: any useful sort of device to stop a robot from driving off will occupy a lot of space that should be reserved for other usage. Theoretically it could be made with a very low barrier around it's edge, but it would still occupy a lot of space.

However, I still think any sort of dedicated platform is overkill if proper precautions are used. Even blocks bolted to a cart or table are fallible and could result in a robot getting tipped over. How do you ensure nothing is caught in the wheels? Or that the robot is sitting just right on the blocks so the wheels don't touch anything? How do you lock down the robot so it can't tip?

The reasonable answer always comes back to "a person has to check" and, in my mind, a person hovering over a disable button is just as good as a person spot-checking everything to do with blocking up a robot, or pulling breakers, or fiddling with code, or whatever the selected safety method is. The important thing is to be redundant in your safety measures and to have a practiced mode of operation so that everyone near the robot knows what could happen and how they must respond. The exact details are largely irrelevant.

Re: Safety Issue: Robots Moving in Pits
 

I noticed last year a LOT of extra space at Peach Tree. Obviously you couldn't add a few more practice fields due to money, personnel, time, etc. (the room in the GWCC could probably hold another 4 or more) but you could add several ~10' square spaces with simple guards around them so people have an out of the way area to practice sub systems. Obviously this only works if the regional had that kind surplus area.

Re: Safety Issue: Robots Moving in Pits
 

Same point I made before.
Most venues I have been to in MAR had some room they could find for this purpose.
All they need is floor really and perhaps scrap rug.

This is my solution. It took me about an hour. It's simple made out of 2x4 and plywood. Basically we will have this on hand at sbpli for testing and people can't put rest their chassis on the wood blocks while still being able to test mechanisms. This is obviously not perfect but it's something.

So yea if anyone here is at sbpli come to our pit and get this thing before you test.

Attachment 18661

Re: Safety Issue: Robots Moving in Pits
 

Great job! Let us know how it works out!

Re: Safety Issue: Robots Moving in Pits
 

How does this solve the frame to wheel offset problem?

Re: Safety Issue: Robots Moving in Pits
 

I don't understand how this is supposed to help. If the chassis is intended to sit on the 2x4 frame, the bottom plane of the robot's wheels will be well below the raised platform on which the tote is sitting. Unless I'm missing something basic about how you are expecting this to work, you've taken the problem of the robot being higher than the floor and turned it the other direction. Am I simply failing to see what it's meant to do?

But even if I am missing something basic, robot frames are not all at the same height off the ground. I'm afraid that this "solution" would not work for a large fraction of the robots I have seen this year.

Re: Safety Issue: Robots Moving in Pits
 

Perhaps not but if it works for his team and even one other that is progress, right?

Re: Safety Issue: Robots Moving in Pits
 

+1

Just make one for your own robot guys.

Re: Safety Issue: Robots Moving in Pits
 

Only assuming that it doesn't not work for some other team so spectacularly that it actually adds to overall the safety risk. For instance, one of the hypothetical teams in this thread that makes mistakes pulling breakers or disabling code may position it improperly, or do a test that shifts robot CG such that it launches off the rig. Among other potential failure modes.

To be clear, this is at least slightly tongue-in-cheek. But there seems to be a lot of "my solution is foolproof, but here, let me build a better fool to break yours" going on. I have no reason to believe that this rig will actually harm anyone at SBPLI, and commend the effort towards what I hope and believe is a full spectrum attempt at safety culture. Kudos.

At the same time, I think we're all simply cautioning that, regardless of your solution, common sense/safety culture is still necessary to implement it properly. Raising the wheels is by no means an entirely safe solution. In fact, I can think of specific cases in which allowing the wheels to spin under power is more dangerous than actually controlling that power digitally or electrically. Again, it takes critical thinking. Anything anywhere in life that is sold as a perfect solution comes with the danger that users will stop thinking about its risks.

Re: Safety Issue: Robots Moving in Pits
 

Indeed, for much of the development of the TechnoKats' mecanum software this year the wheels would have a fit if they were lifted from the ground. The robot would jerk back and forth as the wheels convulsed, and it could easily have rocked itself off a set of blocks. Using closed-loop speed control does not play well with unloaded motors.

Re: Safety Issue: Robots Moving in Pits
 

Really? We've used mecanum (even this year) and never had this "jerking" issue that rocked solidly placed blocks.

I guess I'm picturing jacking the robot up like a car then testing the wheels. Is there really that much sideways movement when your run the wheels off the ground?

This is made to work with a kit chassis build. Because of the lip the elevator can only go so low. Again I reiterate if someone has a chassis that is not a kit of parts one I'm sure they are an experienced team who already has safety procedures in place. I could spend all day building different blocks for different robots but I had to make one that worked with our bot and go from there. It's a step in the right direction and I encourage others to develop the idea better (I'm an electrical guy not a builder).

Re: Safety Issue: Robots Moving in Pits
 

This makes sense in your build site not your pit. Yea trying to run PID's on blocks doesn't work, I know (our bot didn't shake it self of the blocks though).

What would you tell a team trying to test a drive running PID in their pit? Put it on the floor?

I see your point and I may try to make some improvements. This model does work with our robot because our elevator doesn't go lower then the top of the chassi. I may put a sideways 2x4 on top of the existing 2/4 to make it so it's completely level but that would be for other teams. I'm the electrical guy and I see why you would just pull breakers but those things are kinda hard to pull off in a hurry (if they are properly installed they are tight) and this is more of a proof of concept then a done project.

Re: Safety Issue: Robots Moving in Pits
 

Our interim "fix" at the time was to clamp some thick paper (packing material) to the frame so that it rubbed on the wheel and provided some load to the motor being tested.

Back in the IFI controller era many years ago, we did run a robot on the floor in the pit in order to tune and test the autonomous drive routines. We didn't run the actual auton code, just some test commands through the serial "program port" link to tell it to drive forward or backward six inches, or to rotate left or right ten degrees at a time. We did a six foot run once or twice, with advance warning to our pit neighbors and a couple of lines of students making sure nobody was going to be in the danger zone. And always there was someone prepared to slap the big red Emergency Stop mushroom on our auton/disable dongle.