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Thread: Newbie from NZ

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  1. #51
    cheers will do tomorrow and get back
    thanks for the input

  2. #52
    Cheers Andy, sometimes difficult for me to aim information at the appropriate level.

    OP: My use of "referenced to ground" is, as Andy says, a way of saying with the black lead of the meter connected to ground/vehicle earth. I'd intended that (past midnight) to indicate to measure each input, not to measure with the two meter leads across the two inputs.

    Where my thoughts are going on this is to understand if you could, with a diagram, connect an Arduino directly to the controller inputs or whether you'd need a relay board. I'm trying to keep this simple. I am prepared to write the software to host on an Arduino to give you the level of control that you've asked for, but in the first instance I want to see just what we can get away with with wiring. I can tell you that with UK prices, I could implement the control electronics for less than £20 (Arduino Uno, separate 2 relay board, probably a DC-DC convertor to protect the logic from the vehicle voltage spikes). The next challenge would be for you to install the Arduino IDE on a computer and demonstrate to yourself that you can flash/program an Arduino (connect via USB cable, press one button) - and check that a LED on the Arduino is flashing.

    Your shout.

  3. #53
    Something i dont think you have looked at yet is the end of travel can be variable. Think uneven ground, kerbs and even parked on a slope.

    I have a hydraulic lift in the back of my van that does similar to your requirement moving a small platform from the rear floor out and down to the ground .

    You will need to think carefully because the end point at one end (retracted into the boot) is fixed but the other end of the travel is not fixed.

    The most likely is flat ground at the same level as the car verses reversed up to a pavement so 150mm or more higher than the surface the wheels are on.

    If you have a fixed limit switch this will cause problems as the unit will keep driving even though its hit the deck.

    Sorry to add another complication but hope it helps

  4. #54
    Open to ideas
    i Just reread your comment above and i think you may be misunderstanding the concept. There is NOTHING below the chair
    all the lifting is done by 2 support arms which hook under the chairs main handle grips ( at top of machine )
    no plate under it at all
    thanks

  5. #55
    I get there is no plate on your design but just wanted you to think about what happens if the chair touches down prior to the end of travel.

    If the mechanism would continue without damage thats great but if it were to continue down damaging what i presume is an expensive chair not so much.

    I couldnt see your sketches to see the interface between the machine and chair so you may well have this covered

  6. #56
    Hi
    I did write a novel length reply before but i lost the whole post somehow. i will rewrite it now
    The machine is operated by a hand control which when the buttons are released it stops
    As there is nothing under the chair as its lowered if the ground is higher ( say backed into the kerb with a 150mm high footpath ) then the operator
    A if you can drive yourself then you can operate the wired remote
    B if you dont drive then your carer will be in control of the remote...
    Can stop the lowering of the pickup arms by simply releasing the finger off the button. There is a micro switch for when the machine is on a flat platform and it reaches "0" then it cant go lower.
    This would be very unusual in New Zealand as we either drive into a parking space OR parallel park so the lowered machine height is the same as the vehicles standard height so 90 % of the time it will travel to its limit switch. Also if the car is parked on a slope OR road camber then the machine will still lower it parallel to the car ie the road surface. If its too steep then obviously drive around and find a more level park.
    I have an abiloader in my current car for my manual chair and yes if the road is uneven it can jamb the chair in the loader . a good shake usually works but its not 70 kg of chair either :)
    I dont ever want this to be autonomous as it will rip itself to pieces if something went wrong ( like a standard boot hoist if the hoist is lifted higher than the length of rope-cable it will snap the cable and drop 70 kg of machine on your feet ) common sense must prevail
    Anyway
    thanks fr your comments and i need all the brain power i can get to finalize this machine
    Cheers
    Richard

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