Our team was thinking about going over the bump with our robot and the implications it might have on the electrical system. Should we be worried about the electrical system and it getting damaged perhaps we go over the bump too fast and don’t land very smooth. Have any other teams thought about or done anything like this with their robots?
If the electronic components are physically isolated from direct hits, then you should be fine. we put together the 09 kit chassis, with blocks to support the wheels slightly lower than usual, and with 1:1 off the kit transmission we drove it over the ramp several times. The robot landed upside-down on the plastic box housing the cRio and Victors, and the cRio lived. The box could not quite say the same.
One thing to be careful of is metal shavings. Victors + metal shavings = magic smoke. Same with Jaguars.
The control system doesn’t have any moving parts within it (aside from fans; no hard drive), so there’s nothing that’s all that sensitive to shock.
[offtopic]The cRIO is a beast from what I understand; I vaguely recall an anecdote about how the WPI guys spilled salsa in it as they were testing; they removed the cards, wiped the salsa out, and away they went.[/offtopic]
But to answer your question: it shouldn’t be any big deal for the electronics to be onboard a robot experiencing normal contact (smashing into other robots/the wall/the bump).
What will be a big deal is if the electronics themselves are crushed–don’t locate them in a place where other robots are likely to smash into them. Keep all speed controllers, Spikes, and the RIO internal to the robot and protected as much as you can.
EDIT: See the below posts regarding fast bump traversal. You might consider thinking carefully about how your components (especially your battery) are mounted.
This post would argue otherwise. Be careful with your precious (and expensive) components!
I’m not sure I agree with the conclusions reached by the previous two posters. Somewhere around here there is a post detailing some damage sustained to Jaguar fans from bump testing performed by team 488. There is also a warning by Al S. about potential damage to the battery that may result from shock loading.
Our team will be placing shock absorbing material under the mount of our electronics board and perhaps additional shock absorbing material for both the Jaguars and battery.
Holy cow! I don’t think there’s anything anyone could design to protect the electronics from a fast bump traversal, though–I think that’s a driver education issue.
Good to know, though. Thanks!
Oh sure there is. After all, there are applications where the electronics must survive shock loads far in excess of what FRC might see.
My opinion is that things like fasteners and connections will be more of a worry.
Nonetheless, testing has convinced 1676 to mount the electronics to a relatively stiff plate, and provide some shock-mounting of that plate relative to the frame. In addition, all connections will be mechanically secured (over and above the existing frictional retention) and screws (e.g., Jaguar, Victor) will have blue Loctite or similar. Wiring will be carefully managed and fastened tightly to rigid supports - very little will be left dangling in mid-air.
I would be fascinated to hear what actions other teams are taking or considering in this regard.
I doubt your driver will be thinking how best to protect his electronics when you’re in a playoff match. IMO, it’s best to make your robot as fool proof as possible, and adding some rubber shock absorbers could save you a pretty penny in the long run. I’m not saying its a must, my team hasn’t made our board shock absorbent… yet… but it wont be something we blame on user error if it turns out to be a problem.
Every connection not mechanically secured - for instance PWM into Vic’s and Jag’s, will get hot-glued in place. The electronics will be mounted on extruded polycarb fastened at the ends to provide some give if the robot slams down hard.
In testing with out 2007 robot, we put the robot in hard reverse, then into hard forward. The resulting rocking motion (wide chassis configuration) resulted in the robot slamming down so hard it shattered the housings on two of our victor fans. Those were hard-mounted to the aluminum plate that supported the chassis.
Thus far, we have not planned to use shock mounting for the battery as I had hoped. However, where it is located and the way it is mounted will minimize problems, I hope. We use perforated aluminum sheet and ty wrap everything down to the sheet as close to the component as possible. I don’t recommend hot glue as a rule. The power connection to the wireless adapter seems to me to be the most critical followed by the modules in the Crio. Depending where the heaviest components are located, the 3 plus pounds of the compressor or Crio will definitely move when hit.
In games less bumpy than this year’s, my team has known the helpless dismay of having your robot entirely or mostly die on the field due to an electrical connection being knocked loose.
In addition to advocating the securing of PWMs (hot glue is one option but I have seen the whole glue-gobbed end of the wire pop loose anyway, a few short strips of electrical tape stuck to the right angle may work too) I would call attention to the screw-tightening connections of the clip that wires the PD board to the cRIO. Those connections are, in our experience, definitely less reliable than the other wago connections in the control system.
As far as crimping your other terminals, in general make sure you’re using connectors appropriately sized for the wire, don’t crimp perpendicular to the flat part of the ring terminal/quick disconnect, etc.
Every time I see the title of this thread, I think of surge supressors.
My team is using sergical tubing under the bolts on our electronics board to absorb the shock of going over the bump. We also added a temporary roll cage out of steel because we crushed one of our cRio modules after flipping our robot.
Our team has also worried about the bumpiness of our robot. We were worried more about vibrations and the overall rough ride the electrical board will have to take, there are possibilities that connectors can come loose and it’s just unnecessary complication added to the electrical board. We decided to use springs or rubber absorbers are spacers to mount the electrical board to the frame. If you torque down the small springs (size of the spring in your ball point pen but a little bigger spring constant) it should do a good job as acting like a shock absorber.
We are also using surgical tubing, both on the individual components mounting, and on the mounting of the panel to the robot.
So far it seems to work nicely.
I guess while we are here anyway, we should talk about the vibration isolators that come with the compressor. I am guessing they will not stand up to a lot of the harsh environment we will dish out this season. Those isolators were meant to keep vibration generated by the pump from affecting other devices. Not the other way around.
The tests were conducted at my instruction. It is important to us that the robot be able to withstand the most violent conditions it may see on the field. We do not plan on slowing while moving from zone to zone.
Further testing with our electronics mounted on a 1" thick foam sheet has, so far, eliminated all of the problems we initially experienced – except for deformation of the aluminum plate we’re using to hold the battery temporarily.