crane-----more like a tower

Discussion in 'The Projects Forum' started by extremeads1, Jul 20, 2007.

  1. extremeads1

    Thread Starter Active Member

    Feb 10, 2007
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    friends , i want to build a crane -------more like a tower which are used on dockyards for loading and unloading the containers from the ship and placing them on the ground.
    for this purpose i need to build an intelligent crane that is capable of lifting the object/release the object , decide the position of the object, where it need to be placed .

    i will attach this assembly to the microcontroller so that lifting/unloading,deciding the position will be done by the controller,now the main thing is to construct this crane.

    see, as i wish to the lift the object i need to first drop down the cable which'll lift the object so a motor to drop down the cable i.e DOWN MOTION is required,
    then i need something that will "hold" the container firmly to the cable, i think electromagnet will be the best for this,so i need to wire this electro-magnet to the microcontroller to magnetise/demagnetise it, is this possible ?............................Q.1

    ok.if it's possible and once it holds the container firmly,now i need to lift this container and for this purpose i should pull-up the cable so that container is indirectly lifted i.e UP MOTION is required the same motor used for DOWN MOTION can be used for this motion also, is this possible ? ..................Q.2

    IF YES THIS IS THE FIRST MOTOR I"LL REQUIRE FOR UP/DOWN MOTION ,isnt'it?......................................... .................Q.3

    now i need to decide the position of the container where it is to be placed .

    for this ,i think the best would be FORWARD/REVERSE MOTION of the trolley on the crane with the help of which i can move the container "back" and "forth" .i.e to decide the position either the container will be unloaded from the extreme outer end of the crane or from the extreme inner end .
    NOW THIS IS THE SECOND MOTOR I'LL REQUIRE ,isnt it ?......................Q.4

    BUT NOW THE ASSEMBLY ON WHICH I 'M USING THIS "up/down" and "forward/reverse" motion is static then the containers would be placed only in a particular space so now i need a 360 degree rotataion of the crane so that the container can be lifted/unloaded, placed ANYWHERE within the reach of the crane .....................understood .
    FOR THIS A THIRD MOTOR IS REQUIRED ?.......................Q.5

    Q.6 now my question is, can the wiring of electromagnet, for "holding "the container at the time of pulling the container upwards and then "releasing" the container from the electromagnet at the time when the container reaches down be POSSIBLE ?
    Q.7 and can these three motors be connected to the microcontroller ( can this be possible that the 360 degree rotation be controlled by the USER and only the microcontroller controls "up/down' & "forward/reverse" motion so as to reduce the complexity )..........pls reply
     
  2. 2rlp

    New Member

    Feb 27, 2007
    7
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    A Dockyard crane, that too a container crane is a very complex piece of machinery. There are a lot of points to be considered. The plan of using an electromagnet can spell danger for personnel below, in various situations. I would advise you to seek proffessional help.
     
  3. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,652
    767
    Please tell if what yopu want to build is just a model of a crane or the real thing.

    I work with vessels in port most of my time.

    I think I could help.
     
  4. mrmeval

    Distinguished Member

    Jun 30, 2006
    833
    2
    I'm using an Arduino http://www.arduino.cc and while it's somewhat limited it can drive motors and accept sensor inputs. It's very cheap for what it can do. It would be an inexpensive way to learn enough about controllers to know what more you'd need.

    As to the crane part build it in miniature and make all the controls manual until you can figure out the microcontroller part.
     
  5. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,652
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    Since you intend to build a standard crane (and not a gantry crane which are designed especifically to work with containers) to build something ressembling the real thing you need to reproduce this movements:

    1) The swinging movement of the tower itself around its vertical axis.

    2) The up / down movement of the jib.

    3) The up / down movement of the hook controlled by the "cargo runner" which winds/unwinds around a "drum".

    In a first step, solve the problem of hoisting / lowering the weight "hooked" to the cargo hook. Only few times you will see cargo lifted hanging from an electromagnet (just ferrous scrap or steel pieces).

    Keep min mind that when the operator stops the up / down movement of the hook, a brake (mechanical) closes keeping the whole thing standing still. Safety demands that. Timing of the different mechanisms is delicate.

    When the operator decides to hoist or lower, the brake opens while the motor driving the cargo runner takes the load and rotates as required.

    Believe, this is the core of the story and in real systems is one of the parts that more problems create.

    All said aimed for you to somehow reproduce the real thing.

    Could you go from there?

    Never tried but perhaps you could look for a descriptive manual of a crane used on ships or ashore. Names you could use in your search: Liebherr, IMPSA, Gotwald, ITS, Hagglund, Mitsubishi, Fukushima among many around the world.
     
  6. extremeads1

    Thread Starter Active Member

    Feb 10, 2007
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    do you think the project will be successful if the mecahnical part works out and could it be possible to control all the movements of the crane by so programming the mirocontroller.........................i wish to make it automatic.
     
  7. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    Yes, why not?

    I always dreamed of something like that but never tried.

    In fact I believe that the mechanical part, at least for me, should be the most difficult to achieve.

    Focus you attention on that first step. The rest is conceptually simpler.
     
  8. extremeads1

    Thread Starter Active Member

    Feb 10, 2007
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    0
    Keep min mind that when the operator stops the up / down movement of the hook, a brake (mechanical) closes keeping the whole thing standing still. Safety demands that. Timing of the different mechanisms is delicate.
    this is what you have said for this can you provide me some detailed information as i understood the this thing but how to practically implement i mean whre to position the motors and how to apply brakes when the object once is lifted and release them at te time of placing down......can you pls explain me this
     
  9. Gadget

    Distinguished Member

    Jan 10, 2006
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    Also keep in mind, that once built it will have to pass inspection by the relevent authorities before it can be certified and put to use. With that in mind, it may pay to contact them before you start to see what you can and cant do.... and get whatever assistance they may be able to offer.
     
  10. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    He seems to be trying to build a model not a real one. Isn't it?
     
  11. extremeads1

    Thread Starter Active Member

    Feb 10, 2007
    64
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    sir how ashould i tell ou ,i'm doing a microcontroller based crane so i want to make use of the 3 basic movements (lifting/unloading,forward/reverse of the container,forward/reverse of the crane)of the crane which will be automatic as it would be controlled by the microcontroller.so i dont need a perfect model of the crane but i just need a simple structure that will satisfy the basic movements so that while demonstration of my project i can show those basic movemnts being controlled by microcontroller itself?
    so what do you think would it possible to achieve this ?where can i face the problems in the project?
    I want to show the container being lifted then container pulled back and then dropped down .then the crane moves forward a little bit lifts second container and then pulls it back and then drops it again and then the third container .........
     
  12. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Take a look at the other thread you started about this project.

    At the end of it, I posted a link to a somewhat similar project; elevator simulation using stepper motors. It's not precisely what you're looking for, but much of it is applicable (ie: building a structure, control of stepper motors to move objects, source code, microcontrollers)
     
  13. kender

    Senior Member

    Jan 17, 2007
    263
    0
    There have been a good number of attempts to automate the port cranes. Unfortunately, all of them have been ruined by the port worker trade unions, who don't want to loose the jobs to automation.
     
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