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Budget 2DOF

Discussion in 'DIY Motion Simulator Projects' started by Surferjo86, Jun 10, 2020.

  1. Surferjo86

    Surferjo86 New Member

    Joined:
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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, 4DOF, 6DOF
    My new project will be extremely low budget. Following this chaps design

    Purchases so far:

    Arduino Uno
    x2 High Power Motor Driver Module BTS7960B 43A Arduino Intelligent Vehicle Robot
    x2 400w mobility scooter motors 24v
    24v 800w PSU
    10m bungee chord
    x2 Pit bike chain
    x2 pit bike sprockets
    x2 adjustable anti roll bar with ball sockets
    x1 800mm prop shaft from a MGA

    Total spend so far: £268.84

    My budget is £300

    I'll be using ply and steel for the frame, This creation is going to live in my garage, So will try and keep the frame small and bolt it down

    Not sure if I'll need 24v batteries to help with surge? I've probably gone overboard with motor power.

    Attached Files:

    • Like Like x 3
  2. tomkil192

    tomkil192 Member

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    My Motion Simulator:
    2DOF, DC motor, Arduino
    Great job. Can I ask you what type of seat are you using? it looks light and comfortable.
  3. Surferjo86

    Surferjo86 New Member

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, 4DOF, 6DOF
    Ah, the video isn't mine. It's what I'm basing my construction on.
    Joe
  4. Surferjo86

    Surferjo86 New Member

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, 4DOF, 6DOF
    Cobbled a rough looking seat together today, aiming for a spitfire(ish) cock pit. Need extra high sides for leg support side to side movement. I have some 50mm foam to pad the seat out, As I won't be sat on a parachute.

    I Might make the panel with flaps switch and fake clocks- just so in VR it feels like I'm in a cockpit.

    I'll also be making a spade grip flight stick, I've already made one and a spitfire throttle quadrant using Teensy. I'll be bolting the throttle onto the rig but will have to make a new flight stick and rudder pedal.

    Most of my parts have arrived today. Need to think about constructing something to attach the sprockets to the motors.

    Picking up 50mm x 30mm mild steel box section on Monday for the main frame

    Attached Files:

    • Like Like x 2
  5. Surferjo86

    Surferjo86 New Member

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, 4DOF, 6DOF
    Got some more done on the seat, Foot rest in place, Giant 400mm wheels cut out. I think they might be a little excessive.

    I got my angle iron today for the base and prop shaft supports

    Cost so far:
    anti roll bar £20.00
    ply £30.00
    prop shaft £30.00
    psu £68.24
    motors 400w x2 £70.00
    PCBs £25.00
    sprocket x2 £10.00
    chain x2 £26.00
    angle iron £30.00
    £309.24

    Hoping thats it apart from seat covering.I have some foam and potentiometers laying around.

    Attached Files:

    Last edited: Jun 15, 2020
  6. MarkusB

    MarkusB Well-Known Member Gold Contributor

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, Motion platform
    Hi @Surferjo86,

    your wooden DIY seat and the foot rest look nice.

    I just have some concerns about these giant wooden wheels.
    They are probably meant for achieving huge roll & pitch angles, right? This is not always the best solution. Small and precise movements are often better and more convincing for our brains than large and inaccurate ones.

    People often think that a large pitch angle can simulate strong surge forces, but this is not always true. On the one hand your sense of balance notices large rotation movements, and on the other hand large movements need time, which may result in an offset between the image you see on the monitor and the movements you feel.

    But if you want to go on with your current approach, you should have in mind that the moving center of gravity and the inertia will produce quite some forces, and your build does not look very stable. For example have a look at the points that I have marked in the picture below.
    WeakPoints.png

    Your rig will probably wiggle a lot in all directions when the motors start moving, which will result in rather imprecise movements.
    • Agree Agree x 1
  7. Surferjo86

    Surferjo86 New Member

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, 4DOF, 6DOF

    I'm looking for 35-40 degrees - possibly even less depending on how it feels.

    The rig will be a steel frame 30x50 box section- This is just a mock up with wood screws and key hooks. It will be solid steel and bearings when I'm done.

    The arms are now half the length and will be mounted at the bottom of the seat.

    I intend on doing experiments with the wheels - started big so I notch it down to my liking.


    Thankyou for the interest and advice, The last thing I want to do is shake it apart or hurt myself!

    How many degrees of movement would you advise?
  8. brunoD

    brunoD New Member

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    My Motion Simulator:
    2DOF, Arduino
    Do you play assetto corsa with it ? I am impressed
  9. MarkusB

    MarkusB Well-Known Member Gold Contributor

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, Motion platform
    Since you plan to use a VR headset, you should consider motion cancellation with this amount of rotation.

    Sounds good. I thought this wooden construction would be the final one. This was the reason for my concerns. :)

    This really depends on your personal preferences and what you want to achieve.

    In my opinion 35-40 degrees are rather large angles, but they can surely be fun for flight or rollercoaster simulations.

    I am following a different approach: rather small rotation angles plus g-seat paddles. One example for this approach is the Bergison G-Seat:
    • Like Like x 1
    • Agree Agree x 1
  10. Surferjo86

    Surferjo86 New Member

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, 4DOF, 6DOF
    Had abit of time to carry on with the project.
    Steel frame is pretty much done, just needs cleaning up and painting.
    3D printed my motors mounts, motors fit snug.

    Been concentrating on the flight controls, All integrated into the rig. Hoping to set up force feedback on flight stick and rudder pedals. using a old Thrustmaster with some more powerful motors and mosphets.

    Need to fabricate some mounts for the seat for the lever arms to attach next.

    Attached Files:

    • Like Like x 1
  11. Surferjo86

    Surferjo86 New Member

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, 4DOF, 6DOF
    after a long break, I've managed to get abit more done on the project, ran into some issues with the motors. Using SMC3 the motors only follow the command in the negative response, See poor photo

    If anyone has any idea on how to fix this it would be greatly appreciated.

    Attached Files:

  12. MarkusB

    MarkusB Well-Known Member Gold Contributor

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, Motion platform
    For me this looks like your motors do not have the power to go up again.
    One reason could be that your SMC3 parameters need to be changed. For example, try to increase PWMMax step by step and check how this changes the movements.
    Another reason could be that your motors are too weak for your construction. But my first guess is on the parameters.
    • Like Like x 1
  13. Surferjo86

    Surferjo86 New Member

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, 4DOF, 6DOF
    Sorry for the late reply.
    I put it all the way upto 250 and nothing?

    double checked the wiring. At a loss as to where to go next.

    Attached Files:

  14. MarkusB

    MarkusB Well-Known Member Gold Contributor

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    My Motion Simulator:
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    This is strange. Are your motors connected to your rig?
    If so, you can try to decouple them from these large wooden wheels, so that they can rotate freely without moving the entire rig. Is the behavior still the same?

    Another test would be not to use the sinus wave, but to select "Manual" in SMC3 and then move the slider with your mouse. In this way you may get a better feeling of which movements the motors make and where they stop following the input signal.

    If the motors can rotate freely, you can also decouple the potentiometer and turn it by hand. Then check if the motor react accordingly.
  15. Surferjo86

    Surferjo86 New Member

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, 4DOF, 6DOF
    Yeah, nothing is connected. Motors move freely. Both ways when I physically swap the power over directly from the power supply.

    min smc3 I have been using the manual slider. the motors follow the negative route perfectly. The potentiometer green line follows the command line. But as soon as I lift the slider up. The motors stop and go loose.
    i did play with the potentiometers yesterday.
    When I turn them One way the motor spins, when I turn it the other way, nothing


    Cheers joe
  16. Surferjo86

    Surferjo86 New Member

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, 4DOF, 6DOF

    I've purchased a spare Uno, flashed the firmware. Wired it upto a spare H-bridge. All new wiring completely separate. Triple checked the wiring. A small 5v motor I had and a 5v power supply.

    Same issue?

    The motor moves only when you set to motion to below the green line for the pot signal.

    I'm at a complete loss. Been looking through the code to see if I have to do anything different.
  17. Surferjo86

    Surferjo86 New Member

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, 4DOF, 6DOF
    just cranked all the SMC3 settings up and it working ! just need to dial it all back.
    • Like Like x 1
  18. MarkusB

    MarkusB Well-Known Member Gold Contributor

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, Motion platform
    So that means you solved the problem? In this case: congratulations. Maybe you can post a screenshot of the working settings configuration.
  19. Surferjo86

    Surferjo86 New Member

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, 4DOF, 6DOF
    Getting there now.
    Got her moving now. Which is a relief, I replaced the union board and flashed it. Which resolved the previous issue.

    My new issue is that the motors don’t take any weight. I can out power them by pushing down on the seat.
    I have moved the link arms inward to reduce the mechanical advantage. But the motors cut out under load.
    The motors are 24v Mobility scooter motors, so should have the power + the mechanical advantage of the big wheel.
    I’m guessing my issue is that they can’t draw enough current from the power unit. 24v 33amp 800w one power united per motor.

    if anyone has any advice that would be great.
    I seem to be stumbling at every hurdle!

    Attached Files:

  20. Surferjo86

    Surferjo86 New Member

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    My Motion Simulator:
    2DOF, 3DOF, DC motor, Arduino, 4DOF, 6DOF
    Been busy and looking for some advice on motors

    My issues all stem from the big mobility scooter motors. They seem to be burning out the H bridges. I've double the H-bridges up to reduce the strain. But to no avail.

    The system works perfectly well with a small 24v motor. But when I try and use the big motors it all falls apart. The issues seem to be intermittent. The motors wont raise the rig, sometimes they don't work at all (usually they kill a H bridge) Sometimes they work perfectly well. Sometimes only one side works..
    I've tried everything possible with SMC3

    I'm guessing the motors are destroying the H bridges due to too much current draw? The cause of the motors only moving in one direction is due to the H-bridge damage.

    The big wheels are on bearing and move freely - the rig moves around easily using one hand.
    The motors are geared, from memory the gear ratio is about 20/1

    I've added a picture of a motor I'm thinking of replacing them with, with some motor info in one of the pictures. Any advice would be great.

    Also some pictures of the other work I've done to the rig. Frame and instrument panel - throttle quadrant - gear up/down and force feedback flight stick.

    Attached Files:

    • Like Like x 2