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Thread: Help providing suficient power to my bot!

  1. Re: Help providing suficient power to my bot!

    Quote Originally Posted by Th232 View Post
    Uhh... how are you getting 4 volts from two AAs? Most AAs are at 1.5 V, the highest I've ever seen from AAs were NiZn batteries which are 1.6 V nominal. Then there are 14500s, but I don't really count them as AAs...
    ya! they were brand new batteries i measured them with my meter. it said 4.11V i measured each battery it told me 2.47-ishV!!!

    So a L298. Alright! Ive never used one before, but i'll give it a shot! Theres also this other huge place with electrical components its called "Electronic Warehouse"
    Thanks again guys. Click image for larger version. 

Name:	ArduinoBot1.png 
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ID:	3810This is the schematic for my bot. (Never really made a schematic before)
    Last edited by extentionex; 03-19-2012 at 12:13 AM.

  2. #12
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    Re: Help providing suficient power to my bot!

    Uhh... just to double check, are you sure your multimeter was set to measure volts, and you were measuring across the batteries? No offence, but that is not chemically or physically possible in any battery chemistry that I've ever seen. I also say this because two batteries around 2.47 V should, in series, give you a total of 2.47 + 2.47 = 4.94 V, and not 4.11 V.

    Additionally, why is there a capacitor in series with your motor+diode? I'm hoping that's just a drawing mistake and that it's actually in parallel or something...
    Last edited by Th232; 03-19-2012 at 12:37 AM.

  3. #13
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    Re: Help providing suficient power to my bot!

    Just something I should have emphasized earlier: the L298 is probably a lot overkill for your bot and may possibly not even function at the 3V you are using to drive the motors. Fortunately they are only ~$5 and pretty hard to kill, so if it does not work for this bot, it will probably be useful on some future bot.
    Please pardon the pedantry... and the profanity... and the convoluted speech pattern...
    "You have failed me, Brain!"

  4. Re: Help providing suficient power to my bot!

    Th232. Ya i swear! lol
    My volt meter is set to measure DCV and is set to measure volts. not millivolts or anything. look!
    Attachment 3812Attachment 3813
    The (dot) inbetween the 2.24V isnt visoble. my meter doesnt show it. but i can see it flicker on and off sometimes. its correct.
    These are some super batteries ya?

    Ive got my bot programmed to speed up slow down do some fun turns and stuff.
    I plan on adding some kind off sensors on it.
    I was thinking maybe adding two light detecting resistors.
    What sensors do I use for the bot to detect how close an object is? Like a wall?

  5. #15
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    Re: Help providing suficient power to my bot!

    Link's not working, could you try putting them up again? I still maintain there's something really weird going on there, have you tried with a different meter or put fresh (or at least different) batteries in your meter? The dot flickering makes me wonder, meters with low batteries can go funny.

    The reason I'm still on about this is because it's going beyond "good" or "bad" batteries, it's like me telling you that I can run 100 metres in 3 seconds with no external assistance. There's nothing really unsafe here, but getting false readings when you try even more complex stuff might ruin your day. If anyone else reading this thread has some input I'd like to hear it too.

    As for sensors, Trossen has a range of sensors here:

    http://www.trossenrobotics.com/c/rob...e-sensors.aspx

    I'd go for one of the ultrasonic range sensors, but one of the IRs would also be good. Just depends on what kind of range and field of view you're talking about. IR generally has a shorter range, but the beam is narrower. Ultrasonic can be more accurate and has a longer range, but has a wider beam and will fail if you try to measure distances from sound absorbing materials. Those are all generalisations though, different sensors will vary.

    Another thing to consider would be how they give you output. E.g. grabbing the first IR sensor from the list, the output pin gives out a voltage that varies according to the distance between the sensor and the object. So you'll need to feed the signal into an ADC, then hammer out a function to get distance from voltage (as you can see from the chart, it's not linear). On the other hand, the ultrasonic will send back a signal where its duration is proportional to the distance from the target, so you'll need to trigger it, wait for a return signal and time how long that signal takes.

    In either case, both should be fairly easy to implement, and there should be example code for both floating around somewhere.
    Last edited by Th232; 03-19-2012 at 07:33 PM.

  6. Re: Help providing suficient power to my bot!

    Cool thanks man. You and everyone else have been very helpful! Thanks!

    Ive moved on to another more larger step.
    I did what i could with the robot i showed you guys. I learned alot to! Learned some programming steps and how to keep a robot light weight and all those basic issues on building one.

    Recently I bought 8 servos. 9grams. good tork and small.
    My goal with this new project is to create a programmed fourlegged robot! I want to just start out with getting to programming it completly. Like writiing its entire path and the way it moves only with coding it. no sensors. not yet.
    Later on i will buy some sensors and add that.

    **Ive ran into some problems.... take a look at this code for Arduino Uno.

    #include <Servo.h>
    Servo servo1A;
    Servo servo1B;
    Servo servo2A;
    Servo servo2B;
    Servo servo3A;
    Servo servo3B;
    Servo servo4A;
    Servo servo4B;

    int servoTR1 = 0;
    int servoTR2 = 1;
    int servoTL1 = 3;
    int servoTL2 = 5;
    int servoBL1 = 6;
    int servoBL2 = 9;
    int servoBR1 = 10;
    int servoBR2 =11;

    int i;
    int j;


    void setup()
    {
    servo1A.attach(servoTR1);
    servo1B.attach(servoTR2);
    servo2A.attach(servoTL1);
    servo2B.attach(servoTL2);
    servo3A.attach(servoBL1);
    servo3B.attach(servoBL2);
    servo4A.attach(servoBR1);
    servo4B.attach(servoBR2);

    }


    void loop()
    {
    for (int i=0; i<=90; i=i+90)
    {
    servo1B.write(i);
    delay(300);
    for (int j=0; j<=30; j=j+30)
    {
    servo1A.write(j);
    }
    }
    for (int j=0; j<30; j=j+30)
    {
    servo1A.write(j);
    }
    for (int i=0; i<=90; i=i+90)
    {
    servo2B.write(i);
    delay(300);
    for (int j=0; j<=30; j=j+30)
    {
    servo2A.write(j);
    }
    }
    for (int j=0; j<30; j=j+30)
    {
    servo2A.write(j);
    }
    for (int i=0; i<=90; i=i+90)
    {
    servo3B.write(i);
    delay(300);
    for (int j=0; j<=30; j=j+30)
    {
    servo3A.write(j);
    }
    }
    for (int j=0; j<30; j=j+30)
    {
    servo3A.write(j);
    }
    for (int i=0; i<=90; i=i+90)
    {
    servo4B.write(i);
    delay(300);
    for (int j=0; j<=30; j=j+30)
    {
    servo4A.write(j);
    }
    }
    for (int j=0; j<30; j=j+30)
    {
    servo4A.write(j);
    }
    }


    The problem is the Servos.. for some reason it was working fine like 30 mins ago. but then it started to act up. 3 of the legs go crazy and out of line. they do stuff i didnt even tell them to do or even in the correct time..
    And it throws the whole Loop out!
    i checkd all my wiring its good.
    I have NO clue why there going crazy.
    Do servos over heat?
    Please help


    So far its looking pretty good!
    Check it out!
    Click image for larger version. 

Name:	Photo on 2012-03-21 at 18.51.jpg 
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ID:	3816Click image for larger version. 

Name:	Photo on 2012-03-21 at 18.52.jpg 
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ID:	3817
    I have two of the same batteries i used with my old bot.
    i molded some thick wire to form the legs. havnt made the body yet. still programming it and getting all the bugs out. =]

    what do you guys think?
    any tips?
    Last edited by extentionex; 03-21-2012 at 11:03 PM. Reason: PROBLEMS

  7. #17
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    Re: Help providing suficient power to my bot!

    I notice in the second picture that the wires holding the two servos together extends rather high. I'd recommend shortening that (the two upright bits in that picture) so there's less flex in the leg. Also, the legs don't look like they're all the same dimensions. Best fix that now, use a template if you can. It'll save you some grief in programming later on. Finally, what're you going to do for the chassis, and will it be holding just the breadboard, or the batteries as well?

    Also, did you ever figure out what was wrong with your meter and battery voltages? If you haven't, try measuring the voltage between Vout and GND on your regulator, if that doesn't say 5V then I'm still saying there's something wrong with your meter.
    Last edited by Th232; 03-21-2012 at 09:21 PM.

  8. Re: Help providing suficient power to my bot!

    huh? oh alright. is it true that the longer the wires are on the servos the more chances it can interfere with the others?

    yea my meter is correct. lol its just "special ed"

    but hey could you take a look at my post above yours. I added the code i made. but some of the servos like 6 of them are acting up.
    i dont know what it could be. the code was working fine earlier but now its got a mind of its own...

  9. #19
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    Re: Help providing suficient power to my bot!

    Regarding the signal wires, keep those short as well. Interference is definitely a possibility if the wires act as antennae, especially with a PWM system.

    Could you clarify what you mean by "special ed"? Either your meter is working right or it isn't, and a meter saying a AA battery is above 1.6 volts is not working right...

    Can't help you with the code, I don't use Arduinos. If you're sure your code hasn't changed (and by that I mean you haven't even re-uploaded code onto it) then my first recommendation is to check the batteries. Failing that, try swapping the servo connections around to see if it's a motor problem, specific to certain pins on the Arduino, or something else.

  10. Re: Help providing suficient power to my bot!

    HAHA neverr mind.. gosh i feel stupid. I started thinking "wait a minute? should each arm have its own set of 2AA batterry holder?" so i did that and wa-la! the two legs that i gave each their own 2 AA supply. both connected to the ground on arduino. It works! flawlessly. LOL

    i guess before when i had just two battery holder for all eight servos wasnt enough! xD
    live n learn !

    ill post back if i got any other "real" problems.

    Oh and yes. Th232. I am going to make a very light weight body. out of the same thick wire. ill make it work.
    and yes. only one of the legs is short. i need to fix it. it looks slopy now but just wait! it'll be awesome looking.

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