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ARLISS Team NH

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  • Mark KiblerMark Kibler Posts: 546
    edited 2011-04-10 13:55
    Woah woah woah.. Why don't we have two servo's? I understand that we only had one pin left, but we have not discussed yet if we can free up a pin, or any other capabilities. Like somehow controlling two separate servo's with one pin. Having two BoE's could be a possibility, but that would take up too much space I believe. And you said that not having the two Servo's freed up space two put a bigger piece of plexi glass in between the wheels, but we need atleast one servo somewhere in there to make the ASP-Bot move. Also as one more thing. If we were to have a bar between the two wheels to replicate how a car steers, how would we get that bar to move? We would need to have something to move the bar, potentially another servo that we don't have pins for.


    There are no PIN's available for any more servos. As it is we only have one PIN for two motors (wheels.) PJ said you can't run two motors from one PIN. So we can't split the signal from P14 and send it to both motors (wheels.) Here are two solutions that I see:

    1) Use a mechanical device of some sort to drive two motors with one servo (search the internet and you'll discover that there are several ways to do this.) This is entirely possible but it would involve a major rebuild of the rover's platform. We would essentially have to start all over again.

    2) Tap into the signal from another PIN (it's output.) I've already done this and the results are... funny? slow? better than nothing?

    I plugged the second servo into PIN 13 and it moves about 1/16 of a turn every second. If you program the wheel connected to PIN 14 to move at the same speed (the wheel that turns on when the rover lands), the robot "skips" along the ground reaaaaaaaaaaaaally slow. One wheel moves, then the other, then the first wheel, then the other wheel, 1/16 of a turn at a time. It isn't fast or elegant, but it is forward movement using both servos.

    The CLK wire from the ADC chip goes to P13. Since we haven't built the ADC circuit board for the rover yet, no wire is attached to P13 from the ADC. When it is attached, and because the second servo is tapped into P13, things may go haywire when we attach the ADC to P13. Time will tell.

    The MAWD is attached to the rover's platform and it has an ON-OFF switch now. We still need to:

    1) Make the ADC circuit board

    2) Wire the CO2 sensor to the the BOE

    3) Install both the ADC and the CO2 sensor to the platform

    4) Make and mount the parachute release mechanism

    5) Put a battery holder for the MAWD on the platofrm

    6) Find (and buy) a lightweight 3300 mAh (milliamp hour) battery and mount it on the platform to power the BOE/servos.

    7) Mount the shortwave transmitter on the platform

    Our priorities are #1----> #4.

    REQUEST #1: I'd like everyone to bring your BOE's, BOE-BOT's, servo motors, wires, etc.-- everything I passed out at practice-- to next Sunday's practice.

    REQUEST #2: Can everyone please bring TWO 9-volt alkaline or lithium batteries to practice next Sunday?

    Thanks,

    Mr. Kibler.
    :cool:
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-04-10 14:02
    Well, you can have two servos run from one pin, conceptually, but they'd only have the same direction of rotation if their horns were pointed in the same direction. The thing is, their speeds may not match, given/sharing the same control pulse.
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-04-10 14:51
    Dylan & Andrew,
    It seems that you could use a servo controller.

    Decide whether it's an appropriate, responsible, workable solution, and that you are capable of utilising it. If I get it for you, for the team, then you're bound.

    You don't have much remaining code-space (making some abbreviations in your sensor display DEBUGs would help there). A couple of SEROUT instructions should do it. As I understand things, you just want your platform to travel outward and this could certainly manage.

    You will have to brief Mr Kibler (we've spoken, but you guys need to fill in the blanks.)
    Research and deliberate - and get back to me by Wednesday morning (send me a PM.)

    -- PJA --

    PE -- See 1509, 1510, 1511
  • Mark KiblerMark Kibler Posts: 546
    edited 2011-04-10 14:56
    April 9, 2011

    Attached are current pictures of the ASP-BOT so that everyone can see how much space is-- and isn't-- available on the clear plexiglass platforms. If we add much more, something may have to be removed. The shortwave transmitter? The CO2 sensor and ADC chip? Maybe trade the big heavy RC battery for alighter lithium battery? Physical space will ultimately make some decisions for us.

    ===================================

    Andrew and Dylan: PJ will be posting an intersting option for you to consider shortly. Please give it your full consideration and please reply back to him with you thoughts. He's offering to send you a new piece of technology to use...!

    Mr. Kibler
    :cool:
    1024 x 778 - 114K
    1024 x 778 - 111K
    1024 x 778 - 109K
    1024 x 778 - 119K
  • Chase St. LaurentChase St. Laurent Posts: 17
    edited 2011-04-10 17:07
    Hi all. Sorry that I have not been on for this past week because I was out straight due to a robotics competition from thursday to saturday and then I just finished all my make up homework. Also on monday through wedesday I had to study late each night to take my tests I would have missed on thursday and friday.

    I did not get too much time to think about the current situation with the bot. One idea I did think about is what to do with the servo motors. Someone suggested that we could run two servo motors off of one input, but the bot will certaintly not go straight in that case scenario. The bot NEEDS two independent servo motors to correctly move. One idea of mine is to use the single servo if we can definitly not use two and just use gears to make the single servo opperate both wheels. The only issue I forsee is the space constaint to be able to fit gears and such in the bot. Please give me feedback or any comments on this idea so I can possibly try and develop on it.

    Okay, Im going to bed because I havent been feeling well. http://forums.parallax.com/images/smilies/sick.gif I will try and get online tomorrow.

    Thanks,
    Chase
  • Chase St. LaurentChase St. Laurent Posts: 17
    edited 2011-04-10 17:10
    Just remembered something... Would it be possible to implement the hub cap idea with the parachute release. We could use the force of the landing on the hub cap to release a pin or the like. I feel this would remove the need of another servo and use the energy from our impact with the ground to release the parachute. Please comment.
  • Jake GoldsberryJake Goldsberry Posts: 85
    edited 2011-04-10 18:10
    Chase- I like the idea. I think i could see how that would work, but we would have to make sure that the wheel landed in just the right position every time.

    Dylan- We don't need to steer, we just need to use a single "engine" to power some sort of rod that goes between the two wheels.

    As for the release mechanism, we now have several ideas running around, so lets try to have a couple prototypes ready for this next weekend.

    Thanks,
    -Jake-
  • sylvie369sylvie369 Posts: 1,622
    edited 2011-04-10 18:35
    PJ Allen wrote: »
    Dylan & Andrew,
    It seems that you could use a servo controller.

    Decide whether it's an appropriate, responsible, workable solution, and that you are capable of utilising it. If I get it for you, for the team, then you're bound.

    My first thought when I saw that they're down to one pin was to use a ServoPal: http://www.parallax.com/Store/Accessories/MotorServos/tabid/163/CategoryID/57/List/0/SortField/0/Level/a/ProductID/481/Default.aspx
  • Mark KiblerMark Kibler Posts: 546
    edited 2011-04-10 19:01
    sylvie369 wrote: »

    PJ and I talked by phone this afternoon and from what I recall of the conversation, doesn't the ServoPal need two servo pins to start with? I'll read your link and the information PJ suggested about the Parallax counterpart. It's awfullty doggone nice of him to offer the team a servo controller. It's a bit of technology I haven't used but it certainly would let us power two servos.

    See the Parallax link. Photo below:

    http://www.parallax.com/StoreSearchResults/tabid/768/List/0/SortField/4/ProductID/595/Default.aspx?txtSearch=propeller+servo+controller

    Two things I kicked around with PJ were:

    1) A soccer ball
    2) A hacky sack

    Just kidding. I have two small worries to work through before we accept his kind offer:

    1) How difficult is it to do the additional programming in order to get it working? Is the programming within our skillset; can we get it done in the limited time we have?

    2) Do we have the physical space on the robot's platform? That why I posted the pictures of the ASP-BOT. We still have to mount several pieces of hardware and space is starting to get tight.

    I'm eager to see how Dylan and Andrew respond to his idea, and yours.

    Mark
    250 x 250 - 39K
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-04-10 19:08
    Sylvie,
    You're right. I thought that it required signals from 2 pins, but it's all in the pulse sequence.
    I can certainly send one of those. It would take up a lot less space.
    The Servo pin is P14 and the MAWD is on P15.
    The ServoPAL has that Alarm output. Will that be clear/conflict-free?
  • Mark KiblerMark Kibler Posts: 546
    edited 2011-04-10 19:10
    PJ and Sylvie,

    What does the ServoPal do that the 16-servo controller doesn't (and vice versa)? Does the ServoPal run two servos with just one PULSOUT signal? Do both servos plug into it, with just one servo input wire going to it? How do you program it? What are the pros and cons of the two...?

    Thanks,

    Mark
    :nerd:

    Off to bed
  • Mark KiblerMark Kibler Posts: 546
    edited 2011-04-10 19:11
    PJ Allen wrote: »
    Sylvie,
    You're right. I thought that it required signals from 2 pins, but it's all in the pulse sequence.
    I can certainly send one of those. It would take up a lot less space.
    The Servo pin is P14 and the MAWD is on P15.
    The ServoPAL has that Alarm output. Will that be clear/conflict-free?

    I think the ALM pin/wire is being used by the ADC or the CO2 sensor. Would that be a conflict with the signal? Let me check real quick...
  • Mark KiblerMark Kibler Posts: 546
    edited 2011-04-10 19:17
    PJ,

    We labelled all the wires with masking tape and I see a wire labeled ALM that goes to P3 from either the CO2 sensor or the ADC. I didn't trace it back to the source. Here's what the program code says:

    "ALM PIN 3 ' Wire comes from the CH0 pin on the ADC breadboard to TP1 on the CO2 sensor.

    Seems like a potential conflict (with potential being the operative word.) What do you think?

    ==============

    The servos on the rover are mounted "opposite" each other, with the axle spindles pointed outward, on opposite sides of the platform. If the Servopal sends the same signal to both servos, the rover would spin in circles (I think.)

    servo spindle left <
    platform
    > servo spindle right
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-04-10 19:20
    The ServoPAL costs less and it's very small. You plug it into a BoE servo header and plug your servos into it.
    You communicate to it with one pin (the same Servo pin now in use.)

    From the manual:
    "Interface to the ServoPAL is realized through its /Inp input and Alarm “output”. When the ServoPAL
    powers up, both lines are configured as normally-high inputs, pulled up to a nominal +5V through
    internal 20K to 50K resistances. Commands to the ServoPAL are sent as negative pulses to the /Inp pin.
    If the alarm feature is not used, the BASIC Stamp can use the Alarm pin for any other purpose. If this is
    done, however, you must be careful not to trigger an alarm inadvertently, or else a bus conflict may
    occur."

    Over to you, Sylvie.
  • Mark KiblerMark Kibler Posts: 546
    edited 2011-04-10 19:27
    .
    :surprise: <
    (scratching my head) I'll bet Sylvie slipped off somewhere and left us to muddle over this

    Hmmmmm....

    The CO2 sensor doesn't send an alarm; rather, it outputs millivoltage to the Data Logger. OK, it does output to the ALM pin on the CO2 sensor. But doesn't that ("just"?) makes the alarm light on the CO2 sensor module light up?
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-04-10 19:29
    It's easier, for the likes of me, to communicate with the PropServo Controller using its scripts than to use the ServoPAL pulsing method. However, neither is "rocket science" (I've been dying to use that).

    I could "modify" the ServoPAL so that any Alarm, inadvert or otherwise, would/could never be seen by the Stamp/BoE - it would be out of circuit (worry-free.)
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-04-10 19:34
    The "directions" deal isn't a problem, either; no problems there.
  • Mark KiblerMark Kibler Posts: 546
    edited 2011-04-10 19:34
    PJ Allen wrote: »
    It's easier, for the likes of me, to communicate with the PropServo Controller using its scripts than to use the ServoPAL pulsing method. However, neither is "rocket science" (I've been dying to use that).

    Both the Propeller scripting and the ServoPal pulse method are new(s) to me. Six of one, six of the other. Choose your poison. Half empty or half full. Equally confusing (rocket science is easier!)
    I could "modify" the ServoPAL so that any Alarm, inadvert or otherwise, would/could never be seen by the Stamp/BoE - it would be out of circuit (worry-free.)

    Worry free is good. Also, the ServoPal (I keep wanting to type 'PayPal') looks smaller, and "seems" simpler to figure out and explain to the Rocketeers. Is it?
  • Mark KiblerMark Kibler Posts: 546
    edited 2011-04-10 19:35
    So the code to run either one goes in the Main Program?
  • Mark KiblerMark Kibler Posts: 546
    edited 2011-04-10 19:41
    And if the code is one simple 650 or 850 PULSOUT command that goes to both servos, won't the wheels spin opposite?

    Food for thought, conversation for tomorrow. I'm really off to bed this time.

    "Early to bed, early to rise, stay up too late and get a big AM surprise!"

    Mark
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-04-10 19:55
    Yes. Code goes in the Main Program.
    I'll emphasise that some abbreviations in your existing DEBUG routines may be required, to make good room, so be prepared.

    Hey, I can do a YouTube.
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-04-10 20:44
    OK, I made a YouTube of it -- http://www.youtube.com/watch?v=S0iForm5LQs

    It's running the program I've attached.
  • Mark KiblerMark Kibler Posts: 546
    edited 2011-04-11 11:58
    PJ Allen wrote: »
    OK, I made a YouTube of it -- http://www.youtube.com/watch?v=S0iForm5LQs

    It's running the program I've attached.

    In the video the servos are running in the same direction. From the code you posted it looks like we *may* be able to program them to go in opposite directions (since they're on opposite sides of the rover's platform.

    Casear asks: Is that do-able?

    "Thumbs up?" :thumb:

    or "Thumbs down?" :tongue:

    Beest wishes from Rome - "Veni, vidi, vici"

    Caesar Kibler
    :cool:
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-04-11 13:46
    I'm sorry, Mark, but you should take another look at the video.
    They're running clockwise together, counterclockwise together, one clockwise and the other counterclockwise, and then one counterclockwise and the other clockwise.
    I thought by showing all possible combinations that I couldn't miss.
  • Mark KiblerMark Kibler Posts: 546
    edited 2011-04-11 14:30
    PJ Allen wrote: »
    I'm sorry, Mark, but you should take another look at the video.
    They're running clockwise together, counterclockwise together, one clockwise and the other counterclockwise, and then one counterclockwise and the other clockwise.
    I thought by showing all possible combinations that I couldn't miss.

    I'll take a better, longer look at the video. I downloaded it between classes and looked at it while I was trying to answer 15 questions from 21 different students... not the best way to criticaly analyze something, huh?!

    The 4-pin wires for the ADC converter and the CO2 sensor came from newegg.com today. Now we can do some real soldering. We've been trying to make wiring harnesses with 3- and 4-pin wires that we pirated from old computers in the tech ed room. That didn't work so well.

    More later.

    Mark
    :cool:
  • Mark KiblerMark Kibler Posts: 546
    edited 2011-04-11 14:39
    Hey PJ,

    By gosh those servos DO rotate in both directions, don't they? They rotate together in (near) synchronization in the same direction, and in opposite directions too. It seems like it would do the job nicely, and take up less space.

    We'll leave the decision up to you as to which would work for us better. I'd also like to hear Dylan and Andrew's input. The ServoPal seems smaller but the 16-pin servo controller seems more versatile down the road. I assume that the difficulty level of the programming is similar but you know they say about assumptions. What are your thoughts?

    Mark
    :cool:
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-04-11 15:37
    The ServoPAL will address your situation today, tomorrow will have worries all its own.
    My first thought was of it but for my faulty recollection of its operation. Learning it is a cinch.
    I'm making an extender cable for it. It'll make the cable routing more flexible and won't stand any more proud of the X4 connector than any other servo cable in that regard. I'll take pictures when I've finished.

    By the way -- you guys have a BS2e, but you've written all your code for one slot. You do have a lot more memory available, but your guys probably aren't up to speed on using that yet (see RUN in PBASIC Help.) Thought I'd make mention.
  • Mark KiblerMark Kibler Posts: 546
    edited 2011-04-11 15:41
    :cool:
    PJ Allen wrote: »
    The ServoPAL will address your situation today, tomorrow will have worries all its own.
    My first thought was of it but for my faulty recollection of its operation. Learning it is a cinch.
    I'm making an extender cable for it. It'll make the cable routing more flexible and won't stand any more proud of the X4 connector than any other servo cable in that regard. I'll take pictures when I've finished.

    By the way -- you guys have a BS2e, but you've written all your code for one slot. You do have a lot more memory available, but your guys probably aren't up to speed on using that yet (see RUN in PBASIC Help.) Thought I'd make mention.

    Yes, we have a few various stamps (courtesy of Parallax.) It depends on whose BOE gets connected to the serial cable. We have bs2, bs2e, and bs2pe... but only one, maybe two of each. Nad they're scattered all over the southern half of New Hampshire, never to meet until Sunday's practice.

    Did I hear the dinner bell?! :innocent:

    More later,

    Mark
  • Dylan LandryDylan Landry Posts: 235
    edited 2011-04-11 16:43
    P.J and Mr. Kibler,
    Andrew and I have looked at the servoPal before, but it was a solution to a different problem. Like you have both been saying, I too believe that it seems like our best option to still controlling two servos.
    Although this brings up another problem, space. But I believe that we can mount all of this together on the ASP-Bot's platform.
  • Emily RoseEmily Rose Posts: 53
    edited 2011-04-11 16:59
    Hey guys,
    This may sound stupid but don't we need the servos to go in different directions for the ASP-BOT to move forward?
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