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possible bot base — Parallax Forums

possible bot base

GrampsGramps Posts: 117
edited 2010-08-19 14:19 in General Discussion
Two of these scooters might make a very nice and powerful robot base for a total price of $125............





http://cgi.ebay.com/Razor-E150-Electric-Scooter-Red-/320575532203?pt=LH_DefaultDomain_0


Gramps

Comments

  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2010-08-13 17:00
    A robotics engineer should only need one.. :)

    I see balancing robot here...

    OBC
  • ercoerco Posts: 20,260
    edited 2010-08-14 09:19
    Gramps: Good find! I've posted a few times about the motors & controllers from http://tncscooters.com/partsdb.php?type=ES , and per your post, I agree that these chinese scooter parts are a good value. I built an electric bike and the motor output is scary! Great for a big powerful robot or battlebot. Might be a little dangerous delivering sodas in a house, though!

    http://www.youtube.com/watch?v=eYh2JaHsdak the wife can't keep up on her stock Giant electric bike!
  • GadgetmanGadgetman Posts: 2,436
    edited 2010-08-14 14:46
    Those bike conversions can be dangerous. And possibly illegal...

    Here in Norway, they're only allowed to run as a 'supporting engine,' that is, they only run as long as the rider actually pedals. And they're required to cut off entirely at speeds over 25Km/h.
    Anything more and you're talking about an electric MC, with all the paperwork that entails.

    Oh, and(again, here in Norway) the scooters themselves may be illegal if they have a top speed over 8Km/h. Then they're classed as a motor vehicle and suddenly comes under road-traffic laws. (Which means type-certification and a lot of other mess.)
    One TV-host was careless enough to use a gasoline-powered model on his show once.
    Ouch...

    It may not hurt to check up on local laws before doing anything to bicycles, or even just driving one of those scooters anywhere. (Note that road-traffic laws may also cover usage on private roads. It does here.)
    And the 'supporting engine' mod is a really good idea. You don't want to arrive at an intersection, miss the off-button and... well... panic...
  • localrogerlocalroger Posts: 3,452
    edited 2010-08-14 20:20
    In the US electric bicycles are fully exempt from registration as motor vehicles as long as they are under 750 watts power and 20 miles/hr fully motorized top speed with a 150 lb rider. This is a Federal law, trumping the myriad of state regulations on the matter. There is no regulation as to manufacture so you could probably get away with a lot in violation of these limits without being caught; all the police are going to see is an electric scooter, and even if they clock you at 35 MPH you can always say you were pedaling or going downhill.
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2010-08-14 21:13
    Funny, I have the guts from two of those....

    The motor is rated at 24V 135Watt (Model: MY6812)

    The 'original' batteries are two generic SLA batteries rated at 12V 4AH wired in series. I would seriously consider a LiFePO4 battery here.

    The brake is a clamp style friction brake connected to a hand cable. <- they sorta work, but not great
  • Ken GraceyKen Gracey Posts: 7,401
    edited 2010-08-14 21:47
    Gramps, the cost of the individual components of that Razor are probably 5x the cost of the whole scooter. I'm with you on this idea - get a couple of those things. You get the battery, wheels, motors, etc. Heck, you might even use the platform - why not?

    10 mph is a fast robot, too!

    Looks like fun.
  • GadgetmanGadgetman Posts: 2,436
    edited 2010-08-15 00:43
    Friction brake?

    Really?

    Sounds like a good project to learn about regenerative braking...
    (May also be speed-controlled, so that it automatically begins braking whenever the kid gets it over 15mph when going downhill... )
  • legoman132legoman132 Posts: 87
    edited 2010-08-15 06:05
    From my experience with scooters like this, you may have to push it to a few miles an hour before the motor kicks in. not sure if that is true for all small scooters (someone else probably knows lots more), but that's what I read about a similarly sized one I tried to repair for a friend. shouldent be a problem with a new speed controller though. however an HB-25 might not cut it, as lots of scooters of all sizes i have seen use 24 volts (the HB-25 has a max voltage of 16 volts according to the website). You could rewire the batteries to give 12 volts, reducing the speed (i think), but where's the fun in that?
    So, unless I'm wrong about the speed controller or the motor voltage (I probably am) we would have to find one of the many speed controllers that is better suited. (i just realized that the stock peed controller wouldn't be best suited anyway, as there is no reverse for the "see object in close proximity to front of robot, stop, back up, turn away, and continue driving" maneuver.
  • Jay KickliterJay Kickliter Posts: 446
    edited 2010-08-15 09:00
    Glad I read this. As I wrote in my other thread, I have a feeling that I picked bad motors for making my balancing robot.

    Beau, do you happen to know what chain size this uses? Also, with a chain drive, do you feel there would be too much backlash for a balancing robot? I just noticed a way that with minimal welding and no cutting I could mount some motors and up high and bearing supported shafts where my current motors are.

    I was looking at some NPC motors on a battlebots site, but these scooters are cheaper than the individual motors.
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2010-08-15 22:26
    Gadgetman,

    "Friction brake?..Really?" - I'll try to take a picture tomorrow ... basically a rotating cylinder attached to the wheel with a metal strip/band that encompasses most of the cylinder ... one end of the metal strip is anchored while the other end is attached to the brake line cable. As the cable is pulled the metal strip applies pressure/friction equally around the cylinder causing a braking effect.

    Jay Kickliter,

    "Beau, do you happen to know what chain size this uses? Also, with a chain drive, do you feel there would be too much backlash for a balancing robot?" - mine is timing belt driven rather than a chain.



    Edit:

    Gadgetman,

    Attached is an image of the brake housing(I apologize for the dirt)Brake.jpg. You can see the metal band that would surround the metal cylinder. You can see the metal cylinder in the Back.jpg image and the 4-hole screw pattern that matches the wheel. Notice some 'polishing' effect due to use on the brake cylinder.

    Jay Kickliter,

    The difference between belt vs. chain on a scooter from the same manufacturer is just a model difference, I feel that the same motor is used. The dimensions I have on the belt    / wheel/sprocket give it about a 1:6.5 ratio from the motor to the wheel.


    Motor Reference:
    Chain Drive
    Belt Drive


    Belt:
    15.5 inches

    Wheel(gear):
    3.25 inches diameter

    Sprocket:
    0.5 inches diameter
    Back.jpg
    800 x 600 - 61K
    Front.jpg
    800 x 600 - 84K
    Brake.jpg
    800 x 600 - 131K
  • Jay KickliterJay Kickliter Posts: 446
    edited 2010-08-19 07:24
    One more question, are these motors reversible?
  • ercoerco Posts: 20,260
    edited 2010-08-19 09:45
    These are reversible DC PM motors, but a scooter motor controller won't have a reverse function. Some really cheap scooters (not sure about this one) are simply on/off.

    tncscooters.com and electricscooterparts.com have some motor controllers with reverse function in the $25-40 range for 24-36-48V motor apps.
  • Jay KickliterJay Kickliter Posts: 446
    edited 2010-08-19 11:22
    That's what I was asking. I just wondered if the motors were timed to work in one direction.
    erco wrote: »
    These are reversible DC PM motors, but a scooter motor controller won't have a reverse function. Some really cheap scooters (not sure about this one) are simply on/off.

    tncscooters.com and electricscooterparts.com have some motor controllers with reverse function in the $25-40 range for 24-36-48V motor apps.
  • ercoerco Posts: 20,260
    edited 2010-08-19 14:19
    It is definitely possible that the motor timing is advanced to generate more power in the primary direction than reverse.
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