On-Robot Controls
 

Hi all,

Today we mounted our shooter/pickup mechanism onto our robot. The way we have it set up, it starts in a starting position, and in autonomous rotates to shooting position. Throughout the match, we will be rotating between shooting and pickup positions. We found that that the robot is cumbersome to move in any position but the starting position, and since we will almost certainly not be finishing the match in that position, our drivers would like a way to move the robot back to starting position before attempting to move the robot off the field. It would be difficult for us to put a mechanical release on our tilt mechanism, so we were brainstorming different ways to accomplish this.

The best idea we came up with was a "control board" of sorts on the physical robot that could manipulate our tilt motors through disabled-mode code. We would obviously design and implement it in a way that it has minimal (we're talking probably a key switch to activate the board) chance of accidentally activating. We browsed the rules and Q&A, and there are no rules specifically prohibiting this, or any robot movement during "disabled" mode, autonomous or human-controlled. We do see disabled defined in the glossary as "a state in which a ROBOT has been commanded by the Driver Station to deactivate all outputs," but this does not lay the problem to rest for some members of our team (they argue that we aren't prohibited to sudo the robot into listening to our movement instructions for our intended purpose.)

Has anyone had any experience with questioning this definition in years past? We could not find a similar question in this year's Q&A, but we have a question pending. We just wanted to see if any of you guys could be any faster since it's so close to bag&tag.

Thanks! :D

Re: On-Robot Controls
 

What exactly is keeping you from backdriving the motors that control the tilt? It's really simple to do that, generally speaking, thus, no control needed. If you've got a pneumatic cylinder as a locking mechanism, those are pretty trivial to manually activate via their solenoids.

Re: On-Robot Controls
 

Eric,

The roadblock on that path is that we're using a window motor driving a lead screw, which is almost impossible to turn by hand. That was something we considered, but decided we couldn't do without changing our design. Thank you for the alternative though!

Re: On-Robot Controls
 

You will find it impossible to cause the cRIO to activate any motors when the robot is not enabled. That's a safety feature that cannot be bypassed by any code you can write.

My suggestion is that you provide a way to disconnect the motor from its speed controller and then connect it to a separate battery through a manual switch.

Re: On-Robot Controls
 

What would be the difference between this and simply placing a switch that will send forward or reverse voltage to the motor from the robot battery? I don't see how this would be illegal but a separate battery and switch would be.

Honestly I don't understand why it is a problem to have manual control that is inaccessible unless purposefully controlled for safe travel from the field. I don't know why there can't be a blue box allowance of some sort to R54 to allow for safe transport. I think an inspector could judge whether a manual switch would pose a hazard or not. Think of a goalie robot with a ten foot arm extended going through a door to get to the pits...

To the OP, I think it is against the rules since you are controlling an actuator rather than the robot computer per R54.

Re: On-Robot Controls
 

That whole thing about NOT altering the power pathways, maybe?

Some items already have manual control. Pneumatic solenoids, for example. But another thing is that the Manual does not have all of the constraints for any given robot. There is an explicit constraint that robots need to be transported onto and off of the field--but the "easily" part is rather implicit, and is something that the teams need to design for.

Once the robot is off the field and on its cart, and somewhat out of the way, there should be no issue with tethering up quickly, enabling the robot, and bringing the problematic part, whatever it is, in for transport to the pits with power off (or on, if you so choose).

Re: On-Robot Controls
 

Maybe you can remove the locking pins on the window motor to allow easier back drive on the screw?

In the past I have secured a bolt head on the end of my lead screws to drive it with a socket wrench/drill before removing the robot from the field.

Re: On-Robot Controls
 

I get all that, but I would like to see R53 apply to just playing the game not overall. I know you will disagree with that and say it is against the rules, and I am totally aware that it is. Hopefully next time you can use a little less attitude... I said in my own post that manual controls were against the rules (per R54 and as you pointed out R53) I just don't agree with the rules.

I would like to point out that I have never been to an event where you aren't quickly shuffled off the field and out the door to the pits. Our rookie year we had an arm that had to be tethered to pass though a door that we were not allowed to retract at both of our district events. We ended up having to tip the robot on the cart to keep the event staff happy. To get around a very unsafe forced method, a limit switch by the relay made the arm retract. Nobody said a thing, but I now know it was illegal.

In response to the separate battery and switch idea, check R31.

Re: On-Robot Controls
 

I dont know if this is even legal or would work, but what if you had a small laptop on your robot that had the ds program on it and a game-pad attached, and connected directly to the router to move parts of the robot while your on the field? This is just an idea, I have no idea on the legality or workability of this.

You could set your testing code to only move the robot into the stowed position so you wouldn't have to worry about the full code being run, just select test on the ds.

Re: On-Robot Controls
 

I think R30 blue box would make that a issue... But the wrench and lead screw idea could work, as long as it doesn't damage anything in the plastic gearboxes.

Re: On-Robot Controls
 

This would fall under "tethering".

It's workable, sure, but it's not legal under T15. As soon as you're off the field and on the cart, though, you're fine. But we're not talking about that right now.


If I was to make a suggestion...

Build or buy some long handles that hook into the frame of the robot safely. Ideally, those would allow you to pick up the robot and get it off of the field without having to deal with the shooter being tilted back, then you can tether up as soon as you're off to deal with the shooter.

Re: On-Robot Controls
 

4.7.2 R30
The integral mechanical and electrical system of any motor may not be modified. Motors, servos, and electric solenoids
used on the ROBOT shall not be modified in any way, except as follows:
A. The mounting brackets and/or output shaft/interface may be modified to facilitate the physical connection of the
motor to the ROBOT and actuated part.
B. The electrical input leads may be trimmed to length as necessary.
C. The locking pins on the window motors (P/N: 262100-3030 and 262100-3040) may be removed.

Re: On-Robot Controls
 

Sorry.. Long season and reading is hard.

Re: On-Robot Controls
 

I would suggest a connector inline to the motor that you could disconnect and plug into a battery. The circuit would be unmodified while playing, also if you might want a slower speed you could plug in a lower voltage batter to move the mechanism at a more reasonable speed.

Re: On-Robot Controls
 

In my eyes R31 still makes that illegal, it's late in the game but Q&A is the only way to know for sure.

Re: On-Robot Controls
 

The second battery is not on the robot, the player carries it on to the field, unplug the motor from the robot wiring, plugs it in to the motor connector, unplugs the battery when mechanism is upright, and lifts the robot. With a good choice of connectors it should be as easy a mechanical release to operate quickly.

Re: On-Robot Controls
 

I understand what you are saying, just that a second power source is being used to power the robot or a component of the robot. It is a grey area. I agree that it should be fine, but by the word of the manual it is against the rule specified earlier. Again Q&A is the only for sure way to know. I think a mechanical solution is the only way to guarantee compliance.

Re: On-Robot Controls
 

Having a switch on the robot that connects the motor to the battery independent of the control system is a violation of the robot rules. While on the field all robot action must be guaranteed to be controlled by the FMS through the cRio. A switch could potentially bypass this requirement.
Anyone who uses Power Pole connectors (or other types) can have a separate battery that they can use to control the motor externally. We modified a 12 volt drill with Power Poles. We simply connect a motor to it and press the trigger, it also reverses. A tethered operation of the robot is always a good way to make it safe before transport.

Re: On-Robot Controls
 

Al,

Maybe you can clarify this for me then. According to R31:

The only legal source of electrical energy for the ROBOT during the competition, the ROBOT battery, is one of the following approved 12VDC non-spillable lead acid batteries:

Enersys (P/N: NP18-12)
MK Battery (P/N: ES17-12)
Battery Mart (P/N: SLA-12V18)
Sigma (P/N: SP12-18)
Universal Battery (P/N: UB12180)
Power Patrol (P/N: SLA1116)
Werker Battery (P/N: WKA12-18NB)
Power Sonic (P/N: PS-12180 NB)
Yuasa (P/N: NP18-12B)

Exception: Batteries integral to and part of a COTS computing device or self-contained camera are also permitted (e.g. laptop batteries), provided they’re only used to power the COTS computing device and any peripheral COTS USB input devices connected to the COTS computing device and they must be securely fastened to the ROBOT.


Emphasis mine. Last I checked the competition was the whole weekend and didn't end when you left the field. Is there a reason why this is okay even though the rules clearly say that it isn't? Add R35 to that and it seems to me like you broke the rules with your drill unless those rules weren't in the manual at the time.

Re: On-Robot Controls
 

I see what has you concerned now.

Despite the wording you are focusing on, I have never known the "legal source of electrical energy" rule to be applied outside a match.

Re: On-Robot Controls
 

I am not typically a fan of the whole lawyering of the rules thing. But it irks me when some rules are enforced and others are flexible. How are we supposed to know what rules we are allowed to break?

Re: On-Robot Controls
 

The rule actually reads...
R31
The only legal source of electrical energy for the ROBOT during the competition, the ROBOT battery, is one of the following approved 12VDC non-spillable lead acid batteries:
Since the application above is not powering the ROBOT, (it is merely being used when needed to position a single motor) it is legal off the field. While we have one for our use, there is no motor on our 2014 robot that would need to be positioned when the robot is entering or leaving the field. It is a suggested solution for the above questions.

Re: On-Robot Controls
 

We've made a bunch of "Gunn Guns" (inspired by 192). Basically, you take a cheapo cordless drill, remove the motor, and wire leads with Anderson connectors on where the motor used to be. We usually remove the top of the drill casing too. When you pull on the trigger of the Gunn Gun, you give power to the Anderson connector, and anything attached to it.

If you made one of these, you could plug it into your tilt motor after the match, and drive it back up to starting position.