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Robotic arm final year project

Discussion in 'Robotics & Mechatronics' started by vnee, Aug 24, 2006.

  1. vnee

    vnee New Member

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    I am doing robotic arm for my final year project...
    The shoulder must be able to move forward/backward and sideways...
    The elbow must be able to bend and the wrist must be able to turn.. and finally this arm must have clapping motion that resembles human motion..
    I am an electrical engineering student, so I don't really know about the mechanics part..
    Which actuator is better?? Servo motor or pneumatic actuator??
    I just found out about the spherical motor? How do you control it?
    And how about ball joints??

    Please help me and give some idea.. Thank you...
     
  2. akg

    akg New Member

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    afaik pneumatic actuator is suitable for larger machines(also will be more complex in this case). for your purpose it seems a servo would do.
     
  3. barton82

    barton82 New Member

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    same title as mine

    :) i have almost same title as urs,
    mine is to design a controller to control robotic arm, but the arm need to be acts more smooth, more like human motion.
    i using servo motor now cause it use pulse width to control position,
    btw, i also on the way to do it, perharps we can exchange idea in future.
    btw, i am a manufacturing and designing student, is a sub from mechanical.
    i need fast speed servo motor, torque is not important for me. if u got any info about that, do let me know.
     
  4. dave

    Dave New Member

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  5. dknguyen

    dknguyen Well-Known Member

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    Pneumatics are more complicated, but if it's stationary (and you have some budget) and want power and smoothness and decide to go with pnemuatics, look at these Air Muscles. They are like flexible, muscle-like pnemuatic actuators and the price is quite reasonable (not including support equipment like a compressor).

    Info: http://www.shadowrobot.com/airmuscles/
    Prices: http://www.shadowrobot.com/airmuscles/order.shtml
     
  6. vnee

    vnee New Member

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    Thank you for the replies...
    how do we control the air muscle? As I am not a mechanical student, I don't really know about mechanics..
    My supervisor suggested me to just use the servo motor..

    The size of robotic arm required is quite small, only around 1.25'

    Barton82, how many servo motors do you use? And what microcontroller do you use?
     
  7. dknguyen

    dknguyen Well-Known Member

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    You use an air compressor and valves to pump and release air from the air muscle. I probably wouldn't go this way unless I was REALLY REALLY REALLY into the project with more time and money. But using these you can make an arm that works most like a human arm.

    The size of robotic arm required is quite small, only around 1.25'

    The only affordable servo motors are the same motors used in radio-controlled airplanes, cars, helicopters and trucks. So you probably want to go to your local hobby store (that sells this stuff) and look at RC servos. Some brands are Hitec, Futaba, JR, and GWS. Where are you from?

    THe number of servos you use and the microcontroller you use is up to you (it is your project after all). You have to sit down and design the arm. (Although you are in electrical, surely you had to take some mechanical course on torque, moments, and distributed loading right? I know I had to my first and second years in electrical). THat should be enough to figure out how long and heavy your arm can be with the motors.
     
    Last edited: Aug 27, 2006
  8. nitesh_eck

    nitesh_eck New Member

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    i m final year instrumentation engg. and i want to make project based on robotics so plz help me and give me idea if u have .or tell me about a perticular site if u know where i can search projects. ... thanks
     
  9. dknguyen

    dknguyen Well-Known Member

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    Do not add on your completely unrelated questions to someone else's thread and try to hijack it. No one will see it and no one will answer it. Start your own topic.

    Do your own homework. You are final year, there are plenty of ideas out there.
     
  10. ikalogic

    ikalogic Member

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    try using sevos.

    If you need more power, use geared DC motors and chains to transmit the power from part to another. its the simplest and more realistic solution if you are an idividual.

    And specially if you'r an electrical engineering student, don't mess with hydrolics and pnematics.
     
  11. barton82

    barton82 New Member

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    sorry for late reply...
    if use servo to control position and torque 100% from servo,
    then the problem might be stiffness. u will see it move like ROBOt.
    my project actually seperate to different part which undergo by diff student.
    actually i use servo only control position. there is another motor as actuator. the sevo motor use very low torque. and i now looking high speed but low torque servo motor, anyone who got any idea do let me know. the actuator actually is an amplyfire so it only require low torque from servo motor.
    i use microchip as microcontroller coz i found that:
    easy to find,
    more reference,
    some more can get sample.
    any way, i facing many problem. the servo motor need pulse out to control it,
    i try use delay in programming but cant move, maybe is voltage too low.
    then i try use PWM function. use simulator in MPLAB, i can see RC2 is changing from low to high and repeat. but when i program it to chip and use oscillascope to test it.. it show a constant output..
    solve one problem then come out another problem
     
  12. ikalogic

    ikalogic Member

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    look, i am really willing to help you, cause i controlled many many kind of motors using microcontrollers, from tiny motors, to a huge 100A DC motor..

    anyway, we need to know how are you driving the motors?
    Do you know the rated voltage of your motor?

    Also, in the mechanical part, i don't see what you mean by "the sevo motor use very low torque. and i now looking high speed but low torque servo motor, anyone who got any idea do let me know. the actuator actually is an amplyfire so it only require low torque from servo motor."

    Also: PWM is very simple, i don't know why or what you did on matlab, but you don't really need it, you can easily claculate the duty cycle and the frequency, this is it.. sure you need a motor driver adequate to your motor...

    Also, you said "the servo motor need pulse out to control it" .. as far as i know, servos need a ADC to read the actual position of the motor, but then it is controlled as any classic DC motor, but even they are geared so you get low speed and high torque, so you don't need PWM pulses to slow it down... maybe i am wrong?

    I would really apreciate Some schematics, for both electrical and mechanical part - even if they are not compleat- It can help.
     
  13. barton82

    barton82 New Member

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    sorry, look like i din state clearly..
    so many question, which to answer 1st ?

    k, servo motor, as i know. a servo motor is a close loop system.
    when u send a square wave, it will compare to actual position.
    the diff then been amplified use to drive the motor. normal range of servo betwen 0.5ms to 2.5ms +-.. let say u input a 2ms square wave, and the motor is now on 1ms. then the diff will be amplified and start drive the motor. so the motor will move from 1ms and increasing. when move to 2ms, there is no diff and motor will stop. unless the servo is been hacked, then i not sure how..
    refer this:
    http://en.wikipedia.org/wiki/Servo_motor
    http://www.societyofrobots.com/actuators_servos.shtml

    2, PWM
    am i mention i use matlab, not mplab, sorry for the typing error.
    this is part of program:
    LIST p=16f877a

    include<p16f877a.inc>
    org 0x00
    __config 0x3f3a

    start
    call initial
    movlw 0x02
    movwf CCPR1L

    main
    movlw 00h
    movwf PORTC
    goto $

    initial
    bsf STATUS, 5
    movlw 00h
    movwf TRISC
    bcf STATUS, 5

    movlw 0x0c
    movwf CCP1CON

    bsf STATUS, 5
    movlw 0x06
    movwf PR2
    BCF STATUS,5
    movlw 0x07
    movwf T2CON
    clrf CCPR1L
    return
    end
    if use mplab simultor, the RC2 is chancing 1-0 repeatly.
    when i program it to chips and use oscillascope on RC2..
    it show always high..

    another question i gonna attach some drawing but fail.
    now sleepy, here now is 3am..i want sleep. tomorrow try make a reply.
    ty ikalogic
     
  14. ikalogic

    ikalogic Member

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    its late too here now, soo i'll give a short note about servos.

    Servos have - usually - 5 wires. 2 of them connected to the motor. the other 3 are connected to a potentiometer linked to the output shaft.

    all you need to do is use this potentiometer as a voltage divider, and then you will get a variable voltage relative to the angle.

    but i think you understand this.

    now is there a specific question/problem about the servos? please try to elaborate and use compleat words, i make lot of effort reading your replies!

    will look at the code tomorow.
     
  15. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    You're refering to a basic servo system, essentially a mechanical system with feedback. The OP is refering to radio control servos, by far the most popular ones for hobbiest use - these simple require power, and a 0.5mS to 1.5mS pulse telling them where to position themselves, repeated every 20mS or so. The actual workings (which include a motor, feedback pot, and all electronics) are inside the servo casing.
     
  16. gshaan16

    gshaan16 New Member

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    final yr project

    hiii frnds,

    actually i m preparing for my final yr project....i.e robotic arm.
    plzz help me out for my project because i m beginners in robotics plzz send me required data nd information regarding my project i don't know frm wre should i start.
    plzz send me all step wise information so that i can start with it.

    Thank in advance.
     
  17. Krumlink

    Krumlink New Member

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    Ok so you want US to send YOU information for YOUR homework? Whatever happened to kids doing their own homework? Do they all ask for other people to do it?
     
  18. ikalogic

    ikalogic Member

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    start by google, pass by here if you have some specific questions, and end-up with your self and you personal work and efforts. that - believe me - the best way to make it work
     
  19. wannabegeek

    wannabegeek New Member

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    hiiii i m a new entrant..i'm tryin to build a robotic arm ,need d specifications for a simple arm which moves at its hinge &d movement of claw help me out friends
     
    Last edited: Oct 29, 2009
  20. menaka

    menaka New Member

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    hi friends
    im in final year preparing final yr project. pls help me im the begginer. im thinkin to do in robotics or in vlsi. pls tell how to start, what to do, what are the steps o be follwed.
    thank you
     
  21. Vizier87

    Vizier87 Active Member

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    Hey freshies.. read this properly.. and do your homework before posting silly questions.
     

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