Force Feedback

[Andrew Blair]

Has any team constructed a FIRST legal force feedback system for competition? Obviously the problem is getting the feedback motors to run off the operator interface, if that's legal. I would assume with two accelerometers placed 90 degrees from each other, you could get the feedback relatively easily (the feedback only, I hear the sensors are real pains). The last problem I see would be the charge generated by the motors while you're moving the inputs. Could it affect the system in any way I wonder?

[Tom Bottiglieri]

I'm guessing you mean force feedback as some sort of "rumble" device in the operator's control... thing.

[Rickertsen2]

by force feedback do you mean something that vibrates or something that actually resists your movement. I have thought it might be kind of neat to use either style of feedback to communicate how much current the motors are drawing. An accelerometer could work too. I I definately think its a worthwile endevour.
The only ways to communicate back to the OI are through the dashboard port and the LED outputs.

Reading the data off of the dashboard port isn't hard but you need a microcontroller for it.

The other approach is to use the LED outputs. By themselves, these can't source enuogh current to drive a vibrating motor, but you can easily build and amplifier for them.

Now this brings us to the issue of where to get power. Its not available in a great enough quantity from the OI, so you will need an external power source. A battery will do.

As far as the legality of this goes i don't know for sure but i can't think of any rules off the top of my head that it violates. It seems to me that a vibrating motor is the tactile equivalent of and LED.

There are some people somehwere on this forum that built a playstation controller->gameport adapter. I am waiting for them to release the source for this. Once they do, it would be pretty nifty to add force feedback support.

[Al Skierkiewicz]

Many teams have tried in some way to get around the rules on this but the rule book is pretty specific about hooking things to the OI. I don't think that will change in the future but it would be pretty cool. Of course, one more thing for the electrical and software teams to do. If the OI at some point in the future added a few open collector or opto isolator outputs capable of some current and if the rules committee were to allow a second power source at the OI this would turn out some very interesting ideas.

[ahecht]

Now this brings us to the issue of where to get power. Its not available in a great enough quantity from the OI, so you will need an external power source. A battery will do.

As far as the legality of this goes i don't know for sure but i can't think of any rules off the top of my head that it violates. It seems to me that a vibrating motor is the tactile equivalent of and LED.

Once again, FIRSTSearch (http://bobfrank.org/?module=FIRSTsearch) comes to the rescue:
5.3.8 - THE ROBOT>ROBOT RULES>Operator Interface Rules
<R69 (http://bobfrank.org/?module=FIRSTsearch&inp=sectionrules&letter=R&id=69&rules=on&updates=on&qna=on&teams=on&year=2005)> All equipment connected to the Joystick Ports of the Operator Interface must be powered solely through the power available through the port. External power sources of any type are not permitted on any equipment connected to the Joystick Ports. Portable computing devices may not be connected to Joystick input ports on the Operator Interface.

[Jeff Rodriguez]

Regardless of the electronics and whether or not it can be built, how would it work?
Would it simply resist any movement of the joysticks and push back?
Or would it push back when the robots movement is being opposed, i.e. in a pushing match with another robot? Could you do this by comparing the value from the joystick (what the robot should be doing) with perhaps the accelerometer (what the robot is doing) to come up with how much the stick should be pushing back?
If it did give real feedback, would it be useful or just another obstacle for the driver to overcome?
For example, you are face to face with another robot trying to push each other. If you have true feedback, the joystick would be pushing against the drivers movements. Wouldn't that keep the joystick from staying at it's maximum, essentially giving the robot less power and losing the pushing match for you?
I suppose that you could limit the amount of force feedback, but at what point does it just become a nuisance?

[Rickertsen2]

<edit> fixed misquote </edit>

Once again, FIRSTSearch (http://bobfrank.org/?module=FIRSTsearch) comes to the rescue:
well, that pretty much rules out any sort of Force feedback. In order to have force feedback, you need power. Without power we are stuck.

If it did give real feedback, would it be useful or just another obstacle for the driver to overcome?
I have a force feedback joystick that i use for certian games and i have never found the force feedback to be a nuisance but rather helps immerse the operator. It never gets soo strong that you cannot overpower it or so that it significangly throws you off course.

[Andrew Blair]

^(Rickertsen2, you got your copy paste screwed up. I think Ogre said that, not me)

Well, even if it can't be done legally, it would still be interesting. First of all, I mean actual, dynamic force feedback that helps show the driver where he's being pushed. Accelerometers would be the device of choice, placed 90 degrees perpendicular to eachother, so as to provide x-vector and y-vector. In the joysticks, there would simply be a small motor attached to the appropriate axis via a belt. When you got hit from the side, the x-axis would jerk accordingly in parrallel. Programming it directly would be very simple, accelerometer_x=x_motor, I think. However, I would think some kind of filter would need to be in place in order to keep the feedback from actually controlling the robot on it's own, to distinguish human inputs from ones just sent to the feedback system. As for it jerking out of your hands, probably not, as it would be a small motor with a belt that would slip against much backpressure.

I'm wondering if you can get power from the joystick outputs/inputs. It would seem to me that you could run a small, albeit small motor off 9 volts, 1.5 amps. Actually, thats quite a bit of power, if we could get to it. If I remember correctly you can run LEDs from them. Correct me if I'm wrong please!

[Alan Anderson]

You're not thinking far enough outside the box, folks. Remember, there's more than joystick ports on the OI.

[Andrew Blair]

You're not thinking far enough outside the box, folks. Remember, there's more than joystick ports on the OI.

Aha! You mean splicing out power from the competition port, then running a motor controller to it, controlled by outputs from the operator interface? Seems complicated, but maybe the only option.

Or maybe not.....


-------------Edit-----------------------------
Nope, no good.

<R69> All equipment connected to the Joystick Ports of the Operator Interface must be powered solely through

the power available through the port. External power sources of any type are not permitted on any

equipment connected to the Joystick Ports. Portable computing devices may not be connected to Joystick

input ports on the Operator Interface.

<R70> The Competition Cable at the Alliance Station must connect directly to the Competition Port on the

Operator Interface. No intermediate connectors, cables, or “pigtails” are permitted.

[Alan Anderson]

Aha! You mean splicing out power from the competition port,...
Nope. As the rules you quoted say, tapping into the competition port is not permitted during competition.

So if you need more power than you can get from a joystick port, and you want to control something on the OI using software on the robot, what's left?

[Billfred]

Nope. As the rules you quoted say, tapping into the competition port is not permitted during competition.

So if you need more power than you can get from a joystick port, and you want to control something on the OI using software on the robot, what's left?
Relays?

[Andrew Blair]

A giant Tesla coil that can transmit electricity through .25" Lexan!! No, I really have no idea.......You can't generate the power while your there, like with a little spinny wheel.

[Rickertsen2]

R69 States all power must be derived through "the port" It does not state what "the port" is but i am assuming it is intended to mean the joystick ports. With a rumble style force feedback device you would only need power in short spurts. You could easily build a power supply that hordes power for use in times of high load. I don't know for sure but i don't think this sort of sceme would be possible for the other type of force feedback in which power would be needed for longer durations.

If there were not rules and depending on the internals of the OI, it might be possible to draw power out of other things such as the tether port, dashboard port and power port.

[Andrew Blair]

Okay, so use a capacitor to store the charge while you wait in autonomous, then use it during drive.Maybe only have it kick in in big collisions/current drops/whatever.

[Rickertsen2]

Okay, so use a capacitor to store the charge while you wait in autonomous, then use it during drive.Maybe only have it kick in in big collisions/current drops/whatever.

Exactly! A capacitor and a diode to prevent backflow could be used. You would probably need to limit the inrush to the capacitor when it is first plugged in as well.

[Andrew Blair]

Alright then! One or two capacitor setups, wired into a motor controller, to the motors. This is looking pretty complicated. Maybe thats why nobody seems to have done it..........

[Cuog]

http://img.photobucket.com/albums/v300/dragonwarepc/pinoutGameport.jpg

There are 4 5VDC out pins I'm pretty sure that through programming you can control these. (correct me if im wrong but with some hard thinking it can be done)

For the feedback you would hack apart one of the old black joysticks FIRST used to give us. and add one of the 3 volt radioshack hobby motors connected with a thickish ruberband to some orst of pulley that will pull or push your joystick where the feedback is telling it to, and BOOM you have a forced feedback controller that you can still overpower.

[Andrew Blair]

http://img.photobucket.com/albums/v300/dragonwarepc/pinoutGameport.jpg

There are 4 5VDC out pins I'm pretty sure that through programming you can control these. (correct me if im wrong but with some hard thinking it can be done)

For the feedback you would hack apart one of the old black joysticks FIRST used to give us. and add one of the 3 volt radioshack hobby motors connected with a thickish ruberband to some orst of pulley that will pull or push your joystick where the feedback is telling it to, and BOOM you have a forced feedback controller that you can still overpower.

Exactly what I was thinking. Where'd you get that sheet? I can't read it easily from the post. Lego stuff would actually work great for this.

[Rickertsen2]

Exactly what I was thinking. Where'd you get that sheet? I can't read it easily from the post. Lego stuff would actually work great for this.

I was thinking of hacking an off the shelf force feedback joystick.

That pinout posted above is for a generic gameport. The joystick ports on the OI are slightly different. On ports 1&3 pins 5,8,9,15 are outputs designed for driving small LEDs. on ports 2&4 they are inputs for buttons. The diagram posted above shows these as being +5v which is incorrect for the OI. It is possible to configure these pins to output a voltage on ports 1&3, but they are current limited to 10ma each. That only gets you 80ma in addition to whatever small amount of power is available on pin 1 (5v). A standard lego motor draws a stall current of 300ma @ 5v according to http://www.philohome.com/motors/motorcomp.htm.

[Cuog]

i found it just by googleing "gameport pinout" and it was like in the first 5,

Rickertsen2, thanks for pointing out the slight differences in the RC and computer joysticks i think that could have really messed something up

[Cuog]

The joystick ports on the OI are slightly different. On ports 1&3 pins 5,8,9,15 are outputs designed for driving small LEDs. on ports 2&4 they are inputs for buttons. The diagram posted above shows these as being +5v which is incorrect for the OI. It is possible to configure these pins to output a voltage on ports 1&3, but they are current limited to 10ma each. That only gets you 80ma in addition to whatever small amount of power is available on pin 1 (5v). A standard lego motor draws a stall current of 300ma @ 5v according to http://www.philohome.com/motors/motorcomp.htm.


How do you control the pins via programming?


Yes, I've been intriuged now I must build it,
Cuog

[Rickertsen2]

How do you control the pins via programming?


Yes, I've been intriuged now I must build it,
Cuog
you use the variables :
Pwm1_green
Pwm1_red
Pwm2_green
Pwm2_red
Relay1_red
Relay1_green
Relay2_red
Relay2_green

Which pins these correspond to are listed in the IO reference guide. They are defined in ifi_aliases.h. To use them for something you must override their default behavior which is set up in user_routines.c. Unfortunately these variables are also control the lights on the OI itself, so if you use them for something else, you will no longer have the use of those lights for debug purposes.

[Andrew Blair]

Rickertsen, the hack would be much easier, I must agree. And if the current isn't there, it'll just be sub par. But thats alright, it'll still be give feed back probably.

[Cuog]

Thanks, I have been learning the FIRST specific code and i just didnt know what commands controlled the pins

[DonRotolo]

I'm wondering if you can get power from the joystick outputs/inputs. It would seem to me that you could run a small, albeit small motor off 9 volts, 1.5 amps. Actually, thats quite a bit of power, if we could get to it. If I remember correctly you can run LEDs from them. Correct me if I'm wrong please!
According to IFI "The current limit of the +5V Aux from all 4 ports is about 100mA. The Aux Fault Led will start illumination when the current draw from the +5V Aux Outputs total about 120 mA and the +5V Aux voltage will have dropped to about 4.5 volts. Worse case, short condition: after about 30 seconds, the voltage will be at about 300 mV with a current of about 250 mA."

Now, I don't know if that means 100 mA from each port, or 100 mA from all four combined.

Don

[Andrew Blair]

How does storing current on a capacitor work? I know that the voltage out will not exceed the voltage in (ex: 5 volt cap. with 2.5 volts applied will charge to 2.5 volts), but how does current charge?

[Al Skierkiewicz]

How does storing current on a capacitor work? I know that the voltage out will not exceed the voltage in (ex: 5 volt cap. with 2.5 volts applied will charge to 2.5 volts), but how does current charge?

Capacitors store energy by building up a charge between two plates. The larger the value of the cap the more charge is stored. However, it is not an infinite amount nor anything approaching the charge stored in a battery or that delivered by the OI power supply. The LED outputs on the OI are current limited internally to prevent the OI from handling large amounts of current. In addition the OI +5 volt rail that feeds these outputs is derived from a three terminal regulator that is also current limited and temperature sensitive. IFI had to make some choices in the design and size was one of those. To give us high current, +5 volt outputs, would have required significant design changes and would have resulted in a much larger package. Until electrical rules will allow an external power supply and interface for the OI we will be limited in what we can do at the operator station. Remember, the OI & RC are about as bullet proof as they can be. They take a beating and keep on ticking when they are used as designed.

[Alan Anderson]

Until electrical rules will allow an external power supply and interface for the OI we will be limited in what we can do at the operator station.
So you're still safely within the box too, Al?

Come on, people, take off your blinders! The rules do let us connect externally-powered portable computing devices to the OI. The method is officially documented, and tools for doing it are officially available from IFI. I think it's a perfect way to implement force feedback, or just about any other kind of feedback you want.

[Dave Flowerday]

The rules do let us connect externally-powered portable computing devices to the OI. The method is officially documented, and tools for doing it are officially available from IFI. I think it's a perfect way to implement force feedback, or just about any other kind of feedback you want.Not quite:
Teams are permitted to connect a portable computing device (Laptop computer, PDAs, etc.) to the RS232 Output of the Dashboard Port of the Operator Interface for the purpose of displaying feedback from the robot while competing in Competition matches. Please note that AC power will not be available at the playing field so these devices will have to run on internal batteries.
All equipment connected to the Joystick Ports of the Operator Interface must be powered solely through the power available through the port. External power sources of any type are not permitted on any equipment connected to the Joystick Ports. Portable computing devices may not be connected to Joystick input ports on the Operator Interface.
You may only connect externally-powered devices to the dashboard port. Any device which is connected to the joystick ports may not use external power.

Now I suppose you could try to pull something off where you took a normal joystick and wired in some feedback motors that were controlled by signals coming from the dashboard, such that the feedback circuits were totally isolated from the joystick port circuits, but in my opinion this would really be bending the rules. I would consider such a contraption to be a single "device" and therefore it would not be allowed to be connected to the joystick port(s).

[Rickertsen2]

Not quite:


You may only connect externally-powered devices to the dashboard port. Any device which is connected to the joystick ports may not use external power.

Now I suppose you could try to pull something off where you took a normal joystick and wired in some feedback motors that were controlled by signals coming from the dashboard, such that the feedback circuits were totally isolated from the joystick port circuits, but in my opinion this would really be bending the rules. I would consider such a contraption to be a single "device" and therefore it would not be allowed to be connected to the joystick port(s).

Aha! You figured out the solution. All you need is a simple circuit with a microcontroller, an rs323->ttl level shifter, two motor drivers ( something like an L293D would work), and a simple power supply, and two motors.

[Cuog]

that only works if you dont have a computer conected to that port. But if you change the LED color as said before i think the ports will as well receive that signal.

for example:
On Joystick # 1 and 3:

Pin:
15= Pwm1_green
08= Pwm1_red
09= Pwm2_green
05= Pwm2_red

Just add a 3.0V radioshack hooby motor with its power connected to each of these and then add the bands or whatever to give you the power resisting your push.

Remember we are not trying to actually move the joystick here with alot of torque the intenstion is merely to provide a little user feedback, a 3V motor running at 5V is safe and it will be kinda noisy and will heat up like any motor if it stalls so i would try to avoid making the feedback run alot to avoid burning out a motor.

[Rickertsen2]

that only works if you dont have a computer conected to that port. But if you change the LED color as said before i think the ports will as well receive that signal.

for example:
On Joystick # 1 and 3:

Pin:
15= Pwm1_green
08= Pwm1_red
09= Pwm2_green
05= Pwm2_red

Just add a 3.0V radioshack hooby motor with its power connected to each of these and then add the bands or whatever to give you the power resisting your push.

Remember we are not trying to actually move the joystick here with alot of torque the intenstion is merely to provide a little user feedback, a 3V motor running at 5V is safe and it will be kinda noisy and will heat up like any motor if it stalls so i would try to avoid making the feedback run alot to avoid burning out a motor.


Rather than connect a 3v motor and run it at 5v it might be a little wiser to connect something like a 12v motor and run it at 5v. This way you wouldn't have to worry about thermal issues as much. The off the shelf force feedback joystick i have uses motors that are HUGELY oversized. They are approximately the size of the motors on the FP gearboxes that come in the kit. In any case, you are going to need some gearing in there somewhere. I would still recommend some sort of power storage circuit if you want to try this. I can help out with the design of such a thing if somebody wants to try it.

[lukevanoort]

Could you wire the LED outputs to a on/off switch sort of like a victor but running on voltage, not a PWM signal, then to force feedback motor(s). Then the motors would be powered by a random battery, since the circuit isn't in a tether or joystick ports, it doesn't really matter. The victor(ish) thing acts as an amp to power the motor and it doesn't break any rules as far as I see, and could have tons of power if you needed it.

[Jeff Rodriguez]

Could you wire the LED outputs to a on/off switch sort of like a victor but running on voltage, not a PWM signal, then to force feedback motor(s). Then the motors would be powered by a random battery, since the circuit isn't in a tether or joystick ports, it doesn't really matter. The victor(ish) thing acts as an amp to power the motor and it doesn't break any rules as far as I see, and could have tons of power if you needed it.

All equipment connected to the Joystick Ports of the Operator Interface must be powered solely through the power available through the port. External power sources of any type are not permitted on any equipment connected to the Joystick Ports. Portable computing devices may not be connected to Joystick input ports on the Operator Interface.

It doesn't say electrically connected, it says connected.

[mallot1243]

http://www.danasoft.com/sig/Mallot.jpg

[Cuog]

I think that I will try and do this with either 3V or 12V motors and see what happends but when i do i will certainly post a how-to for anyone interested.

And for power storage would a few dozen 2500(mu)F capacitors be enough?
(I took them off of a motherboard hoping theyd be more useful than an old dead mobo.

[Al Skierkiewicz]

I think that I will try and do this with either 3V or 12V motors and see what happends but when i do i will certainly post a how-to for anyone interested.

And for power storage would a few dozen 2500(mu)F capacitors be enough?
(I took them off of a motherboard hoping theyd be more useful than an old dead mobo.

Nope,
A 3v motor running at 5 volts is still in stall when you start it. The little Radio Shack motor will draw amps when starting and the LED ports can only source 10 ma. That's not 10 ma before cutout or 10 before OI shutdown, it's 10 ma period. Damage to the OI could result. These outputs are specifically designed to feed LEDs and nothing else. Capacitors, like motors, look like a short when you apply power. To have enough to store the current required for a motor would take a week to charge up at 10ma and "NO" you can't charge them up before a match. There is no way around the rules for the OI at the present time.

[Cuog]

So if I understand you correctly it will not work because the 10ma is not enough to power the motors and the power required to power them would damage the OI?

[Al Skierkiewicz]

So if I understand you correctly it will not work because the 10ma is not enough to power the motors and the power required to power them would damage the OI?
Not exactly, just hooking the motor up and turning on the output could damge the OI. The motor appears as a short when power is applied. All DC motors exhibit this charachteristic.

[Cuog]

Ok I think i get what you're saying now, is there anyway that I could prevent a short from appearing then when I turn on the motor initialy?

[Al Skierkiewicz]

Ok I think i get what you're saying now, is there anyway that I could prevent a short from appearing then when I turn on the motor initialy?
No,
All motors are in stall when they start and will draw stall current for a short time before turning and up to speed. Just look up stall current and it will give you an idea how far away you are from using the output for motor drive.

[Rickertsen2]

No,
All motors are in stall when they start and will draw stall current for a short time before turning and up to speed. Just look up stall current and it will give you an idea how far away you are from using the output for motor drive.
I still belive that with a suffeciently advanced power supply, intermittent force feedback is possible.

Somewhere in this thread it was mentioned that 100ma is available of the +5v aux. Lets play it safe and not draw more than 75. That gives us .375w to play with (5x.075). Now lets say out power supply is 80% effecient(pretty conservative) at storing and converting power:
.375x.8=.3w

Lets say we want to use a motor with a 300ma stall current running @ 5v. Thats 1.5w (.300x5).

Ok so we have .3Joules/Sec(watts) available to us. We need 1.5Joules to run our device for 1 second. What percentage of the time can we run our device?
.
.3/1.5=.2 We can run our force feedback thingly 20% of the time!!!. If you are running into things 20% of the time you are in trouble! I should mention that this is an absolute worst case. Most of the time you will not be operating your feedback motor at the full 5v.

How about the amount of energy that we store up during autonomous?
5 x .075 x 15 x .8 = 4.5J Thats enough to run our 1.5 watt device for 3 seconds.

We would probably need an energy storage/current limiting curcuit and a DC-DC boost converter but thats not as scary as it sounds. TI provides a large line of power supply building blocks that require few external components. The current limiting curcuit can be accomplished with only a small handful of discreet components. The energy storage can be as simple as a large capacitor.

How about if we just want to install a tiny vibrating motor in the joystick handle to notify the driver of something. heres one that will do nicely (http://www.allelectronics.com/cgi-bin/category.cgi?category=400&item=DCM-204&type=store). It runs off 62ma at 3v. thats .186 watts. If we again assume an 80% conversion effeciency we can run this thing constantly and have power to spare.

In none of these examples did i even begin to draw off the LED power. There are 8 LED outputs. The spec sheet claims they provide 10 ma each. Thats a whole 80ma more that could potentially be tapped!!

---------- edit -----------
Now that i think about it we have two axis so we will probably have 2 feedback motors. which means twice the power needed.

[Andrew Blair]

Now that i think about it we have two axis so we will probably have 2 feedback motors. which means twice the power needed.

Unless we do as you suggested before and use only a single motor in vibrate for high current alert or maybe speed.

Is there a way to prevent capacitors from looking like shorts? Heres what I'm thinking: As rickertsen posted above, we can run a single vibrate motor off of the current supplied by the OI. I havn't looked at the stall for the motor he suggested, but if we can use a capacitor to supply the stall current for the motor just long enough to get it spinning, it might buffer the input long enough so that the stall position of the motor won't be seen by the OI. It shouldn't take much to do this, so our capacitor could charge almost instantly. I think thats right...

[Al Skierkiewicz]

OK,
Let me go into the long explanation on this so everyone will understand. First and foremost, the input power to the OI is 1.5 amps, period. That accounts for all the internal power, all interface electronics and all I/O including the LED ports. Each LED output is current limited to 10ma by an internal resistor. If you were to measure the output voltage with nothing connected (No current flowing) you would measure 5 volts. Add a load of any type and the output will fall to the load resistance times 10ma( thanks to Ohm's Law! V=I*R). In the case of an LED this will be about 2 volts. Next, the so called "Aux" supply is intended for feeding pots in either joysticks or external INPUT devices only. To fool with this supply risks the OI interpreting any/all joystick input as something other than 127 and sending the robot off to damage itself, the field and the other robots and people around it. Finally, a dead short is still a dead short and there is no black magic that can fix that. A similar motor that was supplied to teams a number of years ago had a stall current of over 12 amps. Although Radio Shack does not rate this motor, expect it to have a stall current of at least 3-5 amps. Attempting to interface a motor with any combination of electronic tricks will pull the OI power down, possibly causing damage, blowing the Aux fuse in the OI and likely preventing you from playing the match if this were to occur on the field.

There is no way to fool a capacitor into being anything other than a short when it is discharged. You may not precharge an OI device under current electrical rules.

[Andrew Blair]

Thank you very much for the detailed explanation Al. I guess this means we really have two, final, final options. A Tesla coil delivering proper wattage routed through the joystick port without frying the OI or the people holding onto the joysticks, or an LED powered motor. Who's got the mylar?

[lukevanoort]

You forgot the caveman option, give the coach a padded bit of PVC to whack the drivers with if they do something stupid. :D

[Andrew Blair]

Ha, the caveman option would be more like an unpadded pvc baton. The safety-renaissanceman would place a pad over the stick.:D

[lukevanoort]

Something occured to me at a team meeting when I was telling a newbie about the time I was planning on turning an umbrella into a taser/cattle prod, why hook up the power from the LED to a joystick motor, when we could hook it up to the driver? We could tune it so it was like a prank buzzer but a bit weaker. Mind you, you wouldn't catch me driving it. :) But from a neurological point of view, this works very well, if you give a litle shock to someone when the motors are drawing too much current so their high speed relexes kick in and they will react much quicker. Or, one of those vibrating motors could be stuck in an armband for a cautionary warning, but that is so much less fun. To avoid frying the OI all this would have my earlier semivictor jobby, and if the arm counts as attached to the OI then we are already breaking the rules due to mitochondria.

[phrontist]

What if the vibrating bit was optically isolated? Would that be kosher?

[gburlison]

What if the vibrating bit was optically isolated? Would that be kosher?
You have to power it from the OI, therefore it can not optically isolated. So one question that has to be answered is can the OI supply enough current to power the joystick and the vibrating motor?

Other questions that come to mind:

If the vibrating device is just a MOTOR with an unbalanced weight, can this be legal since in past years no additional motors are allowed?

On the other hand, if the vibrating bit was a totally self contained, i.e. you would have to open it up to discover that it was a motor with an unbalanced weight inside of a case, could it be legal?

Just some of the questions that come to mind.

[Alan Anderson]

If the vibrating device is just a MOTOR with an unbalanced weight, can this be legal since in past years no additional motors are allowed?The rules consistently define the robot in a way that does not include the OI. The "no additional motors" clause applies only to the robot, and by itself won't prohibit a motor connected to the OI.

[lukevanoort]

Okay, so the setup would be like so. The LED driver connects to an LED, which is in a black plastic tube with a light sensitive resistor on the other end. The resistor is connected to a couple batteries and the vibrating motor, which is mounted on a strap that is put on the driver's arm. When the activation condition is met (too much current drawn, breaker blowing, low voltage, etc.) the LED is turned on, and the resistor allows current to flow to the vibrating motor. The motor then vibrates, warning the driver of that the condition has been met. This may not suppy much force, but it does give quick feedback, while allowing the drivers to keep their eyes on the field. It could also power speakers to give auditory feedback, but that would probably irritate allys.

[Al Skierkiewicz]

The rules consistently define the robot in a way that does not include the OI. The "no additional motors" clause applies only to the robot, and by itself won't prohibit a motor connected to the OI.

I don't think I can agree on this one. The robot and the OI are often though of as one system. I would expect the rules makers to rule against this on those grounds.
To reiterate, all power at the driver station must be derived from the OI EXCEPT a computing device which connects to the Dashboard. A palm with visual, aural or motion monitoring could possibly be acceptable. We used a color palm with flashing red and yellow backgrounds for over current conditions a few years back and that was acceptable.

[gburlison]

This thread is titled "force feedback", but if the intention is to alert the driver/operator to a condition like overcurrent or stall with out the driver taking her eyes off the field, then perhaps a piezo buzzer could be used. It should use less current than a motor and if it is mounted in the joystick, you might even be able to feel it.

[lukevanoort]

I don't think I can agree on this one. The robot and the OI are often though of as one system. I would expect the rules makers to rule against this on those grounds.

5.1.1 What is a FIRST Robot?
A FIRST robot is a remotely operated vehicle designed and built by a FIRST Robotic Competition team to
perform specific tasks when competing in the 2005 competition “Triple Play.”

Besides items directly supplied in the 2005 Kit, teams are allowed to use Additional Parts and Materials
in the construction of their robots.

<R39> Specific items NOT allowed include:
• Batteries different from or in addition to those provided in the Kit.
• Circuit breakers different from those provided in the Kit. Note: the Snap Action brand circuit
breakers provided have unique “trip” characteristics. No substitute brands are permitted.
• Electric motors different from or in addition to those in the Kit.
• Any air compressor, pressure relief valves, or air storage tanks other than those provided in the Kit.
• Hydraulic fluids or hydraulic components.
• Materials classified as hazardous by their MSD Sheets (teams should provide MSD Sheets for any
materials they use that might be considered questionable during robot inspection).

The say the robot is a vehicle, which the OI isn't, then say you can't use extra motors on the robot.

To reiterate, all power at the driver station must be derived from the OI EXCEPT a computing device which connects to the Dashboard. A palm with visual, aural or motion monitoring could possibly be acceptable. We used a color palm with flashing red and yellow backgrounds for over current conditions a few years back and that was acceptable.

Actually the rules never say this. They say that no AC power will be available and all equipment connected to the joystck port must be powered by the joystick port.

[Gdeaver]

I can't seam to find it now but First ruled on many issues for the OI in the Qand A forum. Allot was discussed in2004.

[gburlison]

To reiterate, all power at the driver station must be derived from the OI EXCEPT a computing device which connects to the Dashboard. A palm with visual, aural or motion monitoring could possibly be acceptable. We used a color palm with flashing red and yellow backgrounds for over current conditions a few years back and that was acceptable.
Actually the rules never say this. They say that no AC power will be available and all equipment connected to the joystck port must be powered by the joystick port.
luke, I think you and Al are saying the same thing. I do not understand the difference between your statement and Al's.

<R66> Teams are permitted to connect a portable computing device (Laptop computer, PDAs, etc.) to the RS232 Output of the Dashboard Port of the Operator Interface for the purpose of displaying feedback from the robot while competing in Competition matches. Please note that AC power will not be available at the playing field so these devices will have to run on internal batteries.

<R69> All equipment connected to the Joystick Ports of the Operator Interface must be powered solely through the power available through the port. External power sources of any type are not permitted on any equipment connected to the Joystick Ports. Portable computing devices may not be connected to Joystick input ports on the Operator Interface.


In short EVERYTHING connected to ALL of the joystick ports must be powered by the joystick ports. This is limited to 5V@100ma. If you want to use a battery in the operator station, then you must interface to the dashboard port and use computing device to provide the feedback. The question of whether a vibrating device made out of a motor is still a motor and can it be connected to the OI may have to wait until January to be answered.

[Dave Flowerday]

I don't think I can agree on this one. The robot and the OI are often though of as one system. I would expect the rules makers to rule against this on those grounds.
I think that the question of using motors at the OI is one that hasn't been clearly addressed in the past and would be worth submitting a Q&A over. However, at this time (when we cannot submit Q&As), I wouldn't see any reason why they wouldn't be allowed provided that they meet the other requirements about power and the OI. To me it seems clear that the other robot rules are not applied to the OI so I don't know why this one would be. For example, thinking back to when we were restricted on what materials could be used on the robot, those restrictions did not apply to the OI. And, the OI is not weighed or sized with the robot, is not subject to inspection (at least according to the inspection checklist), etc. Plus, the rules have a separate section dedicated to the OI which are distinct from the rules that apply to the robot.

[Al Skierkiewicz]

This thread is titled "force feedback", but if the intention is to alert the driver/operator to a condition like overcurrent or stall with out the driver taking her eyes off the field, then perhaps a piezo buzzer could be used. It should use less current than a motor and if it is mounted in the joystick, you might even be able to feel it.
This is actually a good idea. The piezo I have here (Radio Shack) doesn't spec current draw but it might make enough noise to be heard. Although it is pretty loud in the driver's station.
Dave brings up a good topic for discussion. The OI hasn't been considered for materials in the past (other than hazardous) but those materials wouldn't give a team an advantage as they might on the robot. Although inspectors do not have a checklist item for the operator interface they do require it to be connected and powered for part of the inspection. Motors in the joysticks wouldn't be obvious at that time but other mods would. I still think of the robot as a system (even though it does have an autonomous mode) and the OI is part of that system.

[Rickertsen2]

I think some more specific and hopefully permissive rules concerning the OI are in order this year. We can sit around and find grey areas all we want but there is still a pretty good chance of our arguements not working with a particular inspector. Hopefully someone like Lavery will take notice of this thread and we will see these grey areas turn a little lighter this year.

[lukevanoort]

I think some more specific and hopefully permissive rules concerning the OI are in order this year. We can sit around and find grey areas all we want but there is still a pretty good chance of our arguements not working with a particular inspector. Hopefully someone like Lavery will take notice of this thread and we will see these grey areas turn a little lighter this year.
I agree one-hundred percent.

[Richard Wallace]

.... We can sit around and find grey areas all we want but there is still a pretty good chance of our arguements not working with a particular inspector. Hopefully someone like Lavery will take notice of this thread and we will see these grey areas turn a little lighter this year.
And come kickoff, if the rules are silent or ambiguous on this point, I hope some pertinent questions will appear early on FIRST Q&A. The responsibility for getting FIRST to clarify the rule rests with teams who plan to use the idea, and that means before bringing the device in question to an event. Please don't leave this to be covered by a team update that appears after the first week or two of regionals are over. It is in everyone's interest to have the same interpretations of rules at all 2006 events.

[Al Skierkiewicz]

I think some more specific and hopefully permissive rules concerning the OI are in order this year. We can sit around and find grey areas all we want but there is still a pretty good chance of our arguements not working with a particular inspector. Hopefully someone like Lavery will take notice of this thread and we will see these grey areas turn a little lighter this year.

Jim,
I think you give me too much credit. Inspectors don't make the rules or interpret them for the most part but we do receive training to make sure we know the intent. In this particular case, the OI rules are more driven by IFI than by any electrical person. The OI was designed for ease of use, interface, etc. and LEDs were considered part of that design. To prevent damage to the OI (and to simplify design) the outputs are current limited so that they only drive LEDs. You can think of it this way...The circuitry has an ouput that swimgs between 0 and +5 volts and there is a resistor in series with the outputs that is selected to provide 10ma to an LED. That means there will not be 5 volts available at the output. With a 10ma load expect the output to only be 2 volts, the standard drop across a forward biased LED.
Now that being said, I would love to have some relaxation of the electrical rules for the OI. Students are coming up with great ideas all the time, many like those in this thread. I would love to see some of them implemented, under the rules of course.

[Eldarion]

Wouldn't this be permissible if a separate power source (e.g. battery) was provided for it? We were allowed to use a laptop, as long as it could run from its own internal power. :confused: Or were computing devices a separate catagory?

[Jeff Rodriguez]

Wouldn't this be permissible if a separate power source (e.g. battery) was provided for it? We were allowed to use a laptop, as long as it could run from its own internal power. :confused: Or were computing devices a separate catagory?

http://www.chiefdelphi.com/forums/showpost.php?p=417463&postcount=10

Read the thread before you post.

[Eldarion]

http://www.chiefdelphi.com/forums/showpost.php?p=417463&postcount=10

Read the thread before you post.

I had read the thread, I guess what I had meant to ask was:

Can the two functions of the joystick (I.E. the joystick "input" and the force feedback "output") be separated, so that the input device is hooked up to the joystick port, and the output device is handled separately? I don't think there would be any internal interconnection, so it would be a simple matter of having two cables come out of the joystick? One to the joystick port on the OI, and the other to whatever is required to drive the force-feedback?

[lukevanoort]

I had read the thread, I guess what I had meant to ask was:

Can the two functions of the joystick (I.E. the joystick "input" and the force feedback "output") be separated, so that the input device is hooked up to the joystick port, and the output device is handled separately? I don't think there would be any internal interconnection, so it would be a simple matter of having two cables come out of the joystick? One to the joystick port on the OI, and the other to whatever is required to drive the force-feedback?
Joystick ports not port. (nitpick, I know) Read the whole thread and the IFI spec sheets for the OI. Also the '05 rules would be a good idea, they may change, but it probably won't have many major changes. Then you'd realize it isn't a simple matter. The rules are the component that cause most of the headaches, for example, I could go and rig this up on one of our old bots for very little money, but it wouldn't be competition legal, at least by '05 standards.