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Thread: Motor selection for an all-terrain 6 wheeled robot

  1. #21

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    Quote Originally Posted by hexagon View Post
    Hi
    I am building an all-terrain (sand, gravel, slopes, STAIRS) robot with a 6-wheeled design emulating Rocker-Bogie suspension. It has to carry a payload of 10kg throughout the arena of about 500m. I need to buy motors which can take this robot over the terrains mentioned. Clearly stair-climbing is the biggest challenge.
    Please suggest the specifications of motors which can do this task. Presently I think a motor of torque 25kg-cm will do the trick. There is no much constraint in the speed of the vehicle.
    Any suggestions regarding the motors and suitable drivers would be great! Also please suggest some shops from where I can procure very reliable motors along with encoders.

    Regards,
    Dear hexagon,
    The best motor suited to your application is car wiper motor or power window motor and is available in automobile shop near you
    They have a lot of torques. If they failed use a bus/truck wiper motor
    To drive these type of motors, you need a motor driver board that can drive up to 30Amps
    You can purchase it from some shops mentioned above but it will cost more than 1500 rupees.
    You can make a driver board for just 75 rupees
    For more details contact me
    Knowledge is nothing but Experience
    Experience is nothing but Involvement
    www.kerarobot.com

  2. #22
    Super Moderator T-1000 docel's Avatar
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    Hey!! Hold on- dont mis-guide the guy!!
    Those are Worm-drive motors. Put them to move 30 kgs around and the worm gear will come off the shaft due to the momentum and the stop/start jerks.
    docel
    ^Anything is possible..
    after YOU prove it!!

    http://bangalorerobotics.tripod.com

  3. #23

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    A four wheel wireless robot works fine with these motors

    stop/start jerks can be avoided by applying soft start and soft stop on PWM
    worm gear will come off the shaft due to the momentum can be overcome by using a chain to drive wheels instead of direct wheel drive by motor
    Knowledge is nothing but Experience
    Experience is nothing but Involvement
    www.kerarobot.com

  4. #24
    Super Moderator T-1000 docel's Avatar
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    You cant do an independent soft Start and Stop PWM for 6 motors, without some real synchronisation.
    Please read the OPs requirements first.
    docel
    ^Anything is possible..
    after YOU prove it!!

    http://bangalorerobotics.tripod.com

  5. #25

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    6 or more motors with independent soft Start and Stop can be done by using an I2C motor driver board to drive each motors
    The I2C motor driver board consists of a low cost PIC(I used PIC16F676), an H-Bridge driver and a MOSFET H-Bridge
    To drive a motor just send a command to the I2C motor driver board from the master PIC (Only needs 2 wires to drive all 6 or more motors)
    See I2C motor driver board schematic that I build: http://www.roboticsindia.com/showthr...t=motor+driver
    Knowledge is nothing but Experience
    Experience is nothing but Involvement
    www.kerarobot.com

  6. #26
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    Quote Originally Posted by vigyanabikshu View Post
    A four wheel wireless robot works fine with these motors

    stop/start jerks can be avoided by applying soft start and soft stop on PWM
    worm gear will come off the shaft due to the momentum can be overcome by using a chain to drive wheels instead of direct wheel drive by motor
    Sure, it does. You can make wired/wireless motors with these motors.
    But the OP needs a 6 wheeled RB suspension. you add up the weight of 6 wiper motors, imagine the rise in total current required to move the bot, and the total weight of the bot.
    These motors work well sometimes in robot wars. But I myself had a lot of bad experience with wiper motors when operated at high torques, mainly because of damage with the gears.
    Also, small wiper motors these days comes with in built cam arrangement. Others, are pretty heavy - close to 2.5 Kg.

    Yes, you can use the motors, but I would suggest you either modify the gear system, or modify the current plan of the robot, as you might need a heavy battery if you are running these motors.
    The simply eat up current, and are pretty difficult to PWM. Trust me, you cannot PWM a Wiper like that. Not with the normal electronics.

    The best bet I would suggest is a 15Kg servo modified for continuous rotation. Expensive, but best.
    .... I didnt do it ! ....

  7. #27
    Super Moderator T-1000 docel's Avatar
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    Quote Originally Posted by vigyanabikshu View Post
    6 or more motors with independent soft Start and Stop can be done by using an I2C motor driver board to drive each motors
    The I2C motor driver board consists of a low cost PIC(I used PIC16F676), an H-Bridge driver and a MOSFET H-Bridge
    To drive a motor just send a command to the I2C motor driver board from the master PIC (Only needs 2 wires to drive all 6 or more motors)
    See I2C motor driver board schematic that I build: http://www.roboticsindia.com/showthr...t=motor+driver
    Have you tried this ?
    docel
    ^Anything is possible..
    after YOU prove it!!

    http://bangalorerobotics.tripod.com

  8. #28
    Senior Member T-1000 akshay66's Avatar
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    Try what allbits reagrding servos.
    Redefine it your way!!!!

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