motor

Discussion in 'The Projects Forum' started by extremeads1, Jul 17, 2007.

  1. extremeads1

    Thread Starter Active Member

    Feb 10, 2007
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    i need to move the object to & fro as well as i require up and down motion for the object can this type of motion be achieved using motors ? if posible how many motors are required for this action ? and can you provide any design for this .(basically i want to move container first to or fro and then up or down )
     
  2. recca02

    Senior Member

    Apr 2, 2007
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    it can be by using rack and pinion gear arrangement.
    it can be achieved easily with the help of two separate drives by changing the polarity of supply of the motor to revert the direction of travel.
    it might be possible to do it by using a single motor too but that wud require a bevel gear + some arrangement to provide movement in single desired direction.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    If you wish to control the motion precisely, you will need to use "stepper motors". They are more complex to control than AC or DC motors, but have very high starting torque, and can be controlled very precisely via a microcontroller and a couple of interface chips (Darlington pairs)

    You could use one stepper motor with it's shaft mounted vertically to control yaw (side to side) and a 2nd motor mechanically connected to the 1st with it's shaft horizontal, and a beam outwards from that for elevation. A 3rd motor could reel in or out a cable attached to a rectangularly shaped arm, connected to the 2nd motor.

    Picture a crane at a construction site. Then you'll understand what I'm saying.
     
  4. SgtWookie

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    Jul 17, 2007
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    Yes, you're correct. You'll need a minimum of two motors - although you MAY be able use a single motor and some sort of transmission or a pair of clutches to shift between driving the cable, or moving the carriage.

    You will also need sensors to detect when the carriage or cable have reached their limits.

    If the objects you need to lift are made of steel or iron, you could use an electromagnet to lift them.

    It's best to carry on such conversations in the forum, so that others may benefit, and that you will receive a quicker response.
     
  5. extremeads1

    Thread Starter Active Member

    Feb 10, 2007
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    so yes you said it rite but how to magnetise and de-magnetise the electromagnet when lifting & unloading the container respectively.
     
  6. SgtWookie

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    Jul 17, 2007
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    You would have to use some kind of a driver circuit.

    For example, use a microcontroller's output as an imput to a Darlington pair; ie: TIP 120, TIP126 or the like. Use the output from that device to drive your electromagnet.

    What kind of driver circuit you need depends upon the lifting magnet you select, which depends upon the size/weight of load that you're planning on moving.

    So, how large and how heavy are these containers?

    Do they have closed tops that are able to support the weight of the contents?
     
  7. extremeads1

    Thread Starter Active Member

    Feb 10, 2007
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    ok now i understand , coming to the container part the containers are not so big what you are thinking of it will be say 5-6inch (length),2 inch(width),3inch (height) not more than these dimension and ofcourse of tin ,moreover they would be empty hence only the weight of the tin body is to be lifted. where should i search for the electromagnets ? do you have an sites or parts information ?pls provide me one ?
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    Well, you certainly can buy them in a number of places.

    Here's one that might do the trick for you at Edmund Scientific:
    [​IMG]

    Link: http://scientificsonline.com/product.asp?pn=3113200&bhcd2=1184961969

    But, that's $12.95 US dollars. You could save yourself some money by just getting magnet wire and winding it on a couple of bobbins, and use perhaps a "U"-clamp from an automotive store; just saw the threads off. You don't even need a "U" shape - just pull the V-belt pulley from a junked car alternator, and wind a bunch of magnet wire around where the belt went. If you're really hard-pressed for money, you could even use wire salvaged from the junked alternator's rotor.

    It would be a good idea to use low-voltage AC to drive the magnet rather than DC, to prevent the core from becoming permanently magnetized. Either that, or you could use a totem-pole type of driver to rapidly switch the polarity of the magnet (opposing polarity square waves on each end)

    As far as stepper motors, you might look at something like PF35T-48L4's - these run just fine on 5v, easy to drive them with just a microcontroller or dedicated circuit using a Darlington driver like ULN2803 (ttl) or ULN2804 (cmos)
     
  9. extremeads1

    Thread Starter Active Member

    Feb 10, 2007
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    so now that i want to build a crane--more like a tower used on dockyards for lifting/unloading the containers and then placing them within the reach of the crane, do you have any compact design for the crane.

    the main motions are
    1)up/down motion of the cable to lift/unload the container
    2)forward/back motion of the trolley over the crane to move the container back/forth to decide the position
    3)& left /right motion of the crane(motor wired at its base to cover up maximum area)
    the problem i'm facing is that once the container is lifted the up/down motor must apply brakes until the container is pulled back/forth or the crane moves left/right direction so that container will not drop down ? to hold the container,
    so do you have any mechanical design for the crane so that the rest things will work out i decided to keep the motors on the ground so that structure will not get loaded ...................so you have any design for the crane.............mate pls help
     
  10. SgtWookie

    Expert

    Jul 17, 2007
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    I was initially envisioning a gantry-style crane. Imagine if you will, a table with no top, and cross-bracing on the legs. Instead of a tabletop, angle iron or aluminum angle is used, with the bottom of the "L" pointing towards the center of the open area.

    Across the width of this structure, you'd place an "I" beam. The I-beam would need to have wheels at both ends, driven by a stepper motor. This would move the I-beam back and fourth across the entire length of the table, or the X-axis.

    Attached to the I-beam by wheels, you would have a truck on which was mounted the reel for the wire cable and power wires for the electromagnet. One stepper motor for controlling the position of the electromagnet (Z-axis) and one stepper motor for controlling the position of the truck on the I-beam.

    You'd wind up with a fair amount of wiring to the truck. Each stepper motor would require at least 4 wires (depending upon the style you chose to use) and the electromagnet would require 2. You could use a ribbon cable for this purpose.

    The advantage of this type of design is that it would be inherently stable. However, it will require a good bit of fixed space. Of course, you could tailor it to whatever size you need to cover. These types of cranes are used quite a bit in factories, so that very large and heavy objects can be easily moved anywhere within the building.

    Building the other type of crane could be more problematic. To ensure stability, you will need a large base, a lot of weight, counterbalances, or a combination of the three to ensure that the crane will not tip over.

    You'll need a motor to rotate the crane, a motor to raise and lower the boom (or re-position it) and a motor to reel in/pay out the structural support and wiring to the electromagnet. Depending upon the load, you may need to use gearing or reduction pulleys.

    You might want to start in on this project by obtaining an inexpensive stepper motor, a microcontroller, and Darlington driver chip.

    Look for a unipolar stepper motor that you can drive with low voltage. That's what I found in the Nippon PF35T series of 2-phase steppers. They run just fine on 5 to 7 volts, and they're quite inexpensive if you shop around. I picked up 60 of the PF35T-48L4 models in a closeout sale several years ago for around $1 apiece. I wrote a simple program for driving it using a Parallax Basic Stamp 2sx, which I wouldn't mind sharing. Of course, it wouldn't do you much good if you obtained a different brand of microcontroller, and would need a lot of additions to do what you're contemplating.

    In reality, you wouldn't HAVE to use a microcontroller; you could build a very simple circuit to drive it with. I came up with an idea for driving a stepper motor using just a clock supply, a 74x299 (universal shift register) TTL IC and a Darlington driver.

    You're also going to need to use position sensors to detect where the crane is. On power-up, your circuit won't know where the crane is located. So, you'll need some kind of position sensing gizmo. It could be as simple as a SPST NC switch, that opens when something bumps into it. However, this won't take care of a stall condition; that is where the stepper motor's torque is not sufficient to move the load. This can easily happen when the speed of the motor is changed rapidly; ie: starting or stopping. You could use a series of photoresistors or phototransistors, a series of switches, even a spiral-cut rod that drives a potentiometer - whatever suits you.
     
  11. SgtWookie

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  12. extremeads1

    Thread Starter Active Member

    Feb 10, 2007
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    so i saw that link can i get those pulleys and other mechanical parts ? and one last question that would i be able to control the movements mentioned in the earlier post by a microcontroller and would i be able to create a simple struture by using tracks on the crane and rest things?
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    Ahhh, you wouldn't have to use those EXACT parts - doing so wouldn't necessarily be desireable. For example, the pulleys they used were quite large in diameter compared to the torque that the stepper motors are able to supply. I would use a smaller diameter, but wider pulley.

    As far as your ability to control the movements and create a structure - I'm honestly beginning to wonder. ;) I'm not going to hand you a completed design - that would defeat the entire purpose of your endeavor, and you would learn very little.
     
  14. extremeads1

    Thread Starter Active Member

    Feb 10, 2007
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    well i understand that but you still didnt repl whether once the structure is assembled could those movements be controlled by the microcontroller ?
     
  15. SgtWookie

    Expert

    Jul 17, 2007
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    It is most certainly possible to do so. This will require experimentation on your part.

    It would help you a great deal to start off by getting at least one single stepper motor, a ULN2803 or ULN2003 Darlington IC, and either a microcontroller IC or other discrete IC's to begin experimentation with it. The ULN2803 has 8 Darlington pairs, the ULN2003 has seven. Either way, your project only requires 3 unipolar steppers plus a driver for the electromagnet. Each motor will use 4 of those Darlington outputs, and the electromagnet will use 1. Your wiring may be a bit less messy if you use the ULN2803's, and you'll have 2 more Darlington drivers to experiment with, or for spares in case you manage to let the smoke out of one of the drivers.

    If you don't have a power supply, you can salvage one from an old PC, and convert it to a bench power supply by adding a few parts (banana jacks, and a 10-watt power resistor to load the 5v supply.)

    Here's a link about converting an ATX form-factor PC supply:
    http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply
     
  16. extremeads1

    Thread Starter Active Member

    Feb 10, 2007
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    after experimenting on this, then i should move towards the structure of the crane and then the programming ,is it so?
     
  17. SgtWookie

    Expert

    Jul 17, 2007
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    You're free to attack this project in any manner you so choose.

    I simply suggested that you experiment with controlling an inexpensive stepper motor to begin with, so that you will gain experience with some vital components of your project first, so that you will become more confident to tackle the rest of your project.

    If you don't feel very confident about controlling stepper motors at this point, then consider interfacing a microcontroller with position-sensing switches, photoresistors, phototransistors, potentiometers or the like. It will be necessary for you to monitor such sensors to enable your microcontroller to detect what position your electromagnet or truck or gantry is in - however you eventually decide to build it.

    What you're proposing to do is somewhat complex. In order to simplify the problem, break it down into smaller pieces. Keep doing that until you get to a piece small enough that you understand it, and can make it perform as you desire. Then it's time to add another piece to it, and make them work in harmony; keeping sight of your eventual goal.

    Before you climb the mountain, you must climb the foothills. But before you do that, I suggest you pack a lunch - because it might be a long walk.
     
  18. extremeads1

    Thread Starter Active Member

    Feb 10, 2007
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    sir i came up with an idea of the Pie-type section or TT section for my structure as it would be easier than any other section as far as i think.....
    now i want that the the horizontal bar of the TT section should be having more length than the height of the vertical bar,so that when the winch will move over the horizontal bar i can cover up maximum X-axis area and for Y-axis i think i should attach wheels to the base of the vertical bar in such a way that the horizontal beam(x-axis) is perpendicular to the motion of the wheels connected at the base of the crane. IMAGINE the " + " sign where the horizontal bar is one with the help of which i 'll move my container left/right and the vertical bar is the upright bar from the ground to which the base wheels are attached resulting in forward/reverse motion of the crane.
    (on the horizontal bar ,a pulley with motor will be mounted to hoist/lower the container) do you think the structure is good enough to hold the wight of the motors ,etc.

    two such TT sections will be placed infront of each other (parallel to one another ) the space between them will povide the container to move through this space. do you think there will be wiring problems of the motors i mean they wont get mingled na ?
     
  19. SgtWookie

    Expert

    Jul 17, 2007
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    Huh? :confused:
    Are you thinking of having the entire crane move on wheels? That's getting quite complex.

    How are you doing with the part getting one stepper motor to work with a microcontroller?

    Perhaps I should go back further - have you built a power supply yet?
     
  20. blueroomelectronics

    AAC Fanatic!

    Jul 22, 2007
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