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2DOF 360deg Motion Simulator

Discussion in 'DIY Motion Simulator Projects' started by peteyj, Aug 7, 2017.

  1. peteyj

    peteyj New Member

    Joined:
    Jul 15, 2017
    Messages:
    4
    Location:
    tasmania
    Balance:
    182Coins
    Ratings:
    +1 / 0 / -0
    My Motion Simulator:
    2DOF, DC motor, AC motor, Arduino, Joyrider
    Hello There,

    Greetings all from Tasmania!,

    I am a computer Technician and Steel fabricator and between a couple of us we have decided to embark on a new project.

    After alot of reading on the forums i thought it was about time to make a post also i am hoping to obtain a diy license for simtools :)

    Our current Project in the design stage is a full 360deg 2dof motion simulator (in similar style to the "Viper" design from maker fare that is shown online in various places to provide a full 360deg of movement on both axis.
    one of the requirements we have is to make the simulator as compact as possible in order for it to be able to operate inside.

    This unit is to be powered by gear reduction 3phase motors with Variable Frequency Drives, these will in turn be controlled by an arduino receiving commands from sim tools via usb from the host pc. The Arduino code will also feature a parking function to return the simulator to its parked position when required.

    we are about to start fabrication on a smaller simulator in order to experiment with controller programming similar to a Joyrider, this will be able to be used to test motion control but will not be full 360deg capable.
    this smaller unit will be powered by smaller 12-24v motors and chain driven. being this unit will not be 360deg capable it removes the requirement for slip rings etc that the larger unit will use.

    Is there anybody on these forums who would be willing to share Arduino sketches or code examples they have written to handle the "Flip" where the signal from the rotary encoders goes past the zero point (ie if the is at say 270deg and is commanded to go to say 25 degrees) i am interested in the various ways people have coded this ( i have read a bit on the forums about this but the more info the better)
    also does anybody have experience with different types of rotary encoders that are suitable for this task?
    we could also use a pair of variable resistors on each axis and reference these together in software to ensure to simulator as an accurate reading of the carrage location at all times and avoid the "dead spot" that can come about at the lower end of the resistors range.

    as for the construction, electrics etc we have most of this planned out already and shouldnt have any issues with putting this together, we will be fabricating most of the structure out of RHS steel.

    to save weight and space in the cockpit we were planning on using a hmd for the display, currently we have a htc vive but due to the light house tracking of these systems i believe this will have difficulty tracking the headset while in the simulator and a camera based head tracking system with a camera mounted inside the simulator such as the occulus rift would be required, this will require more experimentation when we come to that part of the build.

    so after that long winded explaination of our build i am interested in information from anybody who has built or is building a 360deg simulator as i am interested in any insights that you might have.

    that being said, This is not our first rodeo, i am aware of the costs, complexities, etc etc required for this type of build so i would kindly ask to keep comments constructive.
    peteyj, Aug 7, 2017
    #1
  2. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

    Joined:
    Jul 13, 2014
    Messages:
    21,189
    Occupation:
    Innovative tech specialist for NGOs
    Location:
    St Helens, Tasmania, Australia
    Balance:
    148,814Coins
    Ratings:
    +10,919 / 54 / -2
    My Motion Simulator:
    3DOF, DC motor, JRK
    Nice to have another compatriot join us, where are you located in Tassie? I am just south of St Helens on the East Coast.

    People often ask about 360 degree sims but often it does not go much past that as they are costly and there are significant technical issues to overcome, some of which you have already alluded to.

    A working model is a good idea and here is a good example of that approach: https://www.xsimulator.net/community/threads/prototype-pitch-roll-full-rotation.5804/

    There is an interesting idea by @BlazinH on page 1 about using dual 360 Hall sensors and code on page 3.

    And a good discussion about the physics and power needed.
    noorbeast, Aug 7, 2017
    #2
  3. peteyj

    peteyj New Member

    Joined:
    Jul 15, 2017
    Messages:
    4
    Location:
    tasmania
    Balance:
    182Coins
    Ratings:
    +1 / 0 / -0
    My Motion Simulator:
    2DOF, DC motor, AC motor, Arduino, Joyrider
    Hi @noorbeast,
    I'm in Launceston so not too far away,

    i have noticed the whole 360deg sim idea tends to attract a lot of people who abandon the project due to complexity, cost, skills etc, unfortunate but i can understand there is a fair bit to it.
    we toyed with the idea of building a model, have already had a bit of a play with the old lego to try a couple of things out but opted not to build a functional model of the 360deg rig as we its a lot more exciting to test it out on the real thing.

    i did have a read of BlazinH's explanation of how to handle the flip situation, it is quite helpful but nothing helps more than seeing functional code :)
    the hall sensor idea is very similar to a lot of cam position sensors fitted to car engines, I'm thinking maybe a 600p/rotation rotary encoder with a sync pulse when the sim is at 0deg would allow the machine to perform an initialisation upon startup to sync the tracking then just count the pulses in each direction to provide the position information, it may even pay to use a separate Arduino to do the pulse counting and then just have that output to the control Arduino the current position as an integer.... interesting, may order some encoders and have a play

    we were looking at 1hp per axis as with correct balance this should have more than enough power to rotate the sim.
    peteyj, Aug 7, 2017
    #3