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Thread: First Robot

  1. #1
    Hi everyone!

    I'm building my first robot. Now it's not being built or designed with thought of actually fighting; I just want to build one for a bit of fun driving around my house etc. If it goes well then I may build another with the idea of fighting with it.

    It's going to be a 2wd wedge lifter. I have got some motors already I found at my work (http://uk.farnell.com/maxon-motor/21...rpm/dp/1761260) and just need some guidance- recommendations for other parts.

    I don't want to mess around with LiPo's as there's no need seen as I'm not actually fighting with it - what other batteries are viable?

    I need help deciding on what ESC, servos for lifter, transmitter and batteries. Something that is suitable for what I'm doing for also has potential should I want to use them in a proper fighting bot!

    I'm basing the lifter mechanism on this robot here with 2 servos, apart from my wedge is angled and not curved.



    Any help or advice will be great!

    Thanks

  2. #2
    Ocracoke's Avatar
    Team Kaizen

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    Hey there, welcome to the forum!

    I don't want to mess around with LiPo's as there's no need seen as I'm not actually fighting with it - what other batteries are viable?
    I use LiFePO4 batteries in my Beetleweight Shu! which worked quite nicely at the last Beetleweight event I was in though they give out less power than LiPos (a 3S LiFe battery is 9.9v nominal, 3S LiPo is 11.1v nominal). The other alternative is NiMH batteries but the Lithium batteries are most prevalent.

    I need help deciding on what ESC, servos for lifter, transmitter and batteries. Something that is suitable for what I'm doing for also has potential should I want to use them in a proper fighting bot!
    Get a transmitter with mixing built in (like the OrangeRX system) as that will cover you in the event that your ESC doesn't do the mixing for you. As far as ESC's go, for a simple plug and go affair, I use a Sabretooth Dual 5A board. A bit expensive for what it is but it works. I know some folks here have had mixed results in the past but I've not really had any issues in using one.

    With Shu! also being a lifter, I don't use a servo, I use a single Pololu 37mm 67:1 motor (previously a 131:1 motor but I broke the gearbox) which again, gives enough oomph.The 131:1 motor was enough to lift both Shu! and the opponent before it broke.

    I'd recommend going around the build diaries as well to see what works and what doesn't.
    Team Kaizen - Build Diary for all the robots

    AW: Amai, Ikari, Osu, Ramu
    BW: Shu!, The Honey Badger
    FW: Azriel
    MW: Jibril, Kaizen

  3. #3
    Thanks for your reply!

    Being a such a novice, what capacity LifeP04 batteries would I need for a lifter?

    Is that ESC suitable to do motors and servo? What is the basic wiring for a robot, including weapon?

    Sorry if I'm coming across dumb haha!

  4. #4
    So I've started looking at a few parts, can you tell me if these are suitable?

    2 x https://www.ebay.co.uk/itm/HIGH-TORQ...19.m1438.l2649

    https://www.ebay.co.uk/itm/RC-Electr...19.m1438.l2649

    https://www.ebay.co.uk/itm/Absima-2-...cAAOSwo4pYidVc

    Just trying to find a suitable ESC, as I don't really want to oay £50 for a Sabretooth one, any recommendations?

    Thanks.

  5. #5
    Theo's Avatar
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    -I'm not too experienced on servos, so I'm not the best to comment. However, they seem like a good size for a lifter if you're using two.

    -The battery looks a but lacking in power, I should think around 12v is right for beetleweights. You also may want to look for one with less capacity, 2000mAh will likely weigh it down, 1200mAh is a nice capacity.

    -The transmitter has a failsafe which is always a plus, but seems a tad limited with only 2 channels. With 2, you won't be able to have the lifter and a working drive system. You should look for 3 at least with this design, I'd look for 4 minimum personally.

  6. #6
    Thanks Theo! Are you able to recommend a 3/4 channel transmitter?

    Or a suitable ESC?

    Cheers

  7. #7
    Ocracoke's Avatar
    Team Kaizen

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    Are you able to recommend a 3/4 channel transmitter?
    As I mentioned in my last post, a OrangeRX transmitter would do the job here. Alternatively (and this is the one I have use with Shu! before), a FlySky TX/RX works fine as well.

    The batteries you linked to are... OK but for reference, Shu! uses a 3S 9.9v 1500 milliamp LiFePO4 battery for the battery and a separate battery of the same specification for the weapon. Technically, this means the robot is running under volts as the motors are 12v but I've not had any issues in capacity with them.

    Is that ESC suitable to do motors and servo?
    The Sabretooth will run the drive motors. Personally, I wouldn't use a servo as the draw on those through the receiver might cause issues but the flip side is that if you use a servo, you don't need a weapon ESC.

    What is the basic wiring for a robot, including weapon?
    Below is a basic diagram of a drive system ESC where it assumes you have two separate ESCs, one for each drive wheel and the mixing is handled elsewhere. The weapon circuit in Shu! is literally half of this.

    basic_robotics_diagram.png

    If you did get a ESC that has mixing on it, such as the Sabretooth or similar, you'd only have the one ESC in that diagram as above linked to the two motors.
    Last edited by Ocracoke; 12th April 2018 at 22:15.
    Team Kaizen - Build Diary for all the robots

    AW: Amai, Ikari, Osu, Ramu
    BW: Shu!, The Honey Badger
    FW: Azriel
    MW: Jibril, Kaizen

  8. #8
    Deathly Hallows's Avatar
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    I would just add that I understand that each ESC feeds power to the receiver. So if you have two, you are best to remove the middle red wire from the feed from one of those ESC to RX links.

    I did this on my Beetleweight.

  9. #9
    Theo's Avatar
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    I currently have a Hitec Optic 5 iirc. 5 channels, failsafe and two antennae for range and reliability. The fifth channel is a button in the side, ideal for flippers/spinners that use solenoids.

  10. #10
    Thanks everyone for your help! How does the transmitter receiver fit into the wiring diagram?

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