Wheel-chair controller and motor

Discussion in 'The Projects Forum' started by maverik007, Mar 24, 2009.

  1. maverik007

    Thread Starter Member

    Feb 6, 2009
    25
    0
    Hi everyone,

    I am interested in making a wheel chair with joystick control. My intention is to have joystick control for moving in the N-S-E-W directions. I haven't thought of 45 degree relative to normal motion yet, but it might be need in future depending on my experimental work.

    The first thing I have to look at is the motor that I will be using. I want to control the dynamics of the motor by providing specific values of maximum acceleration and velocity. Thus, I'll need feedback from the motors about their current position with a high degree of accuracy. From my understanding, this means that I will have to employ a stepper motor with optical encoders, and a way to decode the encoder output. One solution is using a separate stepper motor and attaching a US Digital optical encoder along with the USB-One Encoder Data Acquisition box, but that might be more expensive than other solutions out there. Any suggestions on what motor could do the same job for me with lesser hardware and money requirements?

    NOTE: The wheelchair is supposed to be capable of moving around a 300 lbs person with a minimum acceptable velocity of 10 ft/sec. Keeping in mind the added weight of the wheelchair itself, I am interested in using motors that are capable of carrying say 400 lbs easily.

    Also, I know of he SN754410 Quad Half-H driver for motor direction control. This chip can provide a maximum of 1-Amp per driver. If I want more current drive, I can add more such chips in parallel, but another IC that is capable of higher driver current per driver would be great. Any suggestions on that count as well?

    FYI, I am doing my own research on google.com and plan to compare notes with the feedback I get here. Would help me get a better grasp over how to design the system.

    Your help will be really appreciated. Thanks in advance!

    :)
     
  2. jj_alukkas

    Well-Known Member

    Jan 8, 2009
    751
    5
    Optical encoders arent necessary.. Just supply pulses according to the joystick's degree of turn.. the more degree, the more speed.. Speed control would be easier.. Why check with encoders and decoders weather the wheel is spinning or not?? servo motors are great for this application. If you use an H bridge, it has an inbuilt braking function..
     
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,173
    397
    " The motor " One drive motor and one steering motor ? Or two drive motors with differential control for speed and direction. One wheel chair I worked with, used as a trailer tractor, has two ,gear reduced, 250 W motors, 11.5A ,@22V. Uses DPDT SW for reverse.
     
  4. maverik007

    Thread Starter Member

    Feb 6, 2009
    25
    0
    Could you please explain why?
     
  5. maverik007

    Thread Starter Member

    Feb 6, 2009
    25
    0

    I haven't worked with servo motors. Do you have any tutorial that would help me grasp the basics before I jump into trying to control them with a PIC?
     
  6. jj_alukkas

    Well-Known Member

    Jan 8, 2009
    751
    5
Loading...