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Question My 4dof motion simulator

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Hale L, Jun 17, 2020.

  1. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
    DC motor, Motion platform, 4DOF
    I am using these motors Capture.PNG
    They are 440Watt motors
    I was originally gonna go with mean well power supply's but they only output 350Watts
    What should I get?
    I will be using 4 motors would two bigger power supply's be better?
    Thanks for the help
  2. Ads Master

    Ads Master

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  3. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
    DC motor, Motion platform, 4DOF
    I guess I didn't include enough information
    The motors are:
    24V dc
    440W
    25 amps
    There are lots of kinds of power supply's and im very confused so any kind of help would be greatly appreciated
    Last edited: Jun 18, 2020
  4. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    • Like Like x 1
  5. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
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    I meant the one I was planning on getting. The psu's that they have get pricey when going over 350 watts. I'm going with two saber tooth 2x32 amp motor drivers don't know if that affects anything
    Last edited: Jun 18, 2020
  6. Damien602

    Damien602 New Member

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  7. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
    DC motor, Motion platform, 4DOF
    I found this, wonder if two of these would work would work? if im powering two motors from one psu do I need more amps. For example if my motors are 25 amps do I need at least 50 amps?
  8. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
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    C6ECAE12-C55C-4AA1-8627-D93FD2F4B2D1.png Just ordered 4 of these power supply’s. I think I should be able to daisy chain two of them then wire them to the saber tooth. Is this the right way to do it?
  9. yellofella

    yellofella Member

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    hi buddy
    Be careful when putting 2 power supplies in parallel as its not as easy as you might think ( daisy chaining as you put it.) There are many mixed views on the subject if you google it but from my understanding you will have to get both supplies outputting the same voltage within a few millivolts. Even if you manage to do this then there will be differences in the 2 power supplies. You may purchase 4 supplies from the same company with matching batch numbers but due to small variances in the components that the supplies are made of they really wont perform as 4 identical supplies. When paired one supply will always work harder than the other and the load wont be evenly shared.
    Also when using the sabertooth driver you will need to deal with the regenerative voltages that the driver produces when the motors brake or change direction. You could use some large resistors and leak it to ground but it will heat the resistors a lot so would need cooling. The best way and the way the manufacturer of the sabertooth suggests is to put a battery in parallel with the supply as an accumulator. This will deal with the voltage spikes and provide added power to your supply. A car battery would be a good start if you want real power as they provide lots of amps fast but to get 24v you will need to wire 2 in series then wire them in parallel with the supply. Now i understand that this may not be possible as for 4 motors you would need 4 power supplies and 8 car battery's and be dealing with massive amounts of available current which could be dangerous if you are not experienced in electrics.
    You may be able to use much smaller battery's like motorbike or alarm backup battery's which will work the same and be more compact but wont be able to supply as much current.
    You stated that your using a 32A sabertooth, 24v/25A motors and 600w power supplies which are all maximum figures that the parts can supply. A well balanced 2dof sim on a universal joint with good angles on the rods wouldn't need anywhere near that much power per motor but a 4dof that lifts all your weight on the motors surely will. The only real way to tell how much you will need is to test(r&d). Try to keep it as simple as you can to start with to get a working sim then increase the power if you need to but also keep in mind that the more current available she sharper the sim will react.
    Maybe you could provide some more info on what design you are thinking of for your sim as this would help members to offer a better opinion on the hardware that you could use.
    Hope this helps
    • Like Like x 1
  10. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
    DC motor, Motion platform, 4DOF
    I plan on having three motors in a triangle so I have heave. The 4th motor is for traction loss, unless they motors are underpowered and I need to use that for another main motor
  11. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
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    https://youtu.be/VvBojB_RUBA
    B
    asing my design off of this
  12. yellofella

    yellofella Member

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    hi again @Hale L
    Thanks for sharing the info on what type of sim you wish to build. I have to say that you haven't chosen an easy design to build for your first sim but im sure with the help from other members and myself you can do it. I would just like to add that any advice that you get from this site from members is just advice and only you can choose to use it or not.
    Ok back to the sim. What hardware have you already got. You said you have 4 of the motors and that you have purchased 4 power supplies so based on that info and the design that you have in mind id have to say that the sabertooth 2x32 probably isnt the best driver for your design due to it being a duel motor driver. I would probably go for a cytron single motor driver so you can use a single 600w power supply per motor.
    Something like this or a more powerful version but remember your supplies will only deliver 25A max
    https://www.robotshop.com/uk/cytron-30a-5-30v-single-brushed-dc-motor-driver.html
    You could buy 4 of them for less than 2 sabertooths 2x32 and will deliver the same punch due to your supplies being 25A. It would eradicate the problem of trying to pair 2 supplies together for more power.
    The motors in the video you posted have encoders or potentiometers built in to them for closed loop feedback. Your motors that you provided a picture of dont have any position feedback device so you are going to have to work out a way of mounting a hall effect potentiometer on them to measure final drive position.
    What is your calculated max weight that you are going to move. You will need to add your weight to a list of other stuff like seat, wheel, pedals, screens, frame weight and so on to calculate the torque you are going to need from the motors to deliver sharp movements against the force of gravity. With 3 motors delivering 25A you would have 1800w/ 75A of combined power but id still try to save as much weight on the platform as you can.
    So this is all theory at this point but you will need to get practical pretty soon so you will need a starting point. I suggest to start with 1 motor only, get a potentiometer mounted to it and connect to a driver and power supply. Download the smc3 software and make the changes needed for your driver. Get position control on 1 motor then get the other two motors working the same. Only then can you really start thinking about frame geometry and stuff.
    I must say that there are easier sims to build. You mentioned that your number 4 motor may get used for traction loss at a later stage. With this design you would have to find a way to keep the centre of gravity low or you will likely turn the sim on its side with you in it when you powerslide the car in the game. My friend found this out years ago on my sim and was only saved by the chance it tipped towards the wall not away from it. Funny now but back then it could have hurt him and took a complete frame redesign with a lot more width for stability before i used traction loss again. Knowing this it may put massive forces through your motor linkage under the platform so would need to be over engineered in the design.
    I myself went for a 2dof with traction loss design and havent changed it much in 10 years. Its still a 2dof with traction loss today if not a very refined version of it. Im currently working on a closed loop stepper motor gseat to add to it but its still a work in progress as im trying to refine the code to work with sim tools and testing but thats the way ive chosen to go as its the only way to get sustained g forces.
    I hope all this helps and if you have any other questions then tap me up buddy.
  13. Gadget999

    Gadget999 Active Member

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    My Motion Simulator:
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    I wasted a lot if time with server power supplies, they do not like fluctuations in power.

    I use 2x 12v batteries and a truck battery charger

    Works perfectly and does not shut down
  14. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
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    Thanks for all the help. I ordered potentiometer and 3D printed mounts for them. I might switch to the cytrons.
  15. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
    DC motor, Motion platform, 4DOF
    Parts list so far:
    4 meanwell power supplies 24v 25A 600w
    4 24v 25A 440w dc motors
    4 Cytron 30A motor drivers
    Arduino Uno R3
    10k pot without mechanical stop
    3D printed pot mounts and gears
    Ball joints/heim joints
    Arduino expansion board(don’t know if I’ll need it)
    Relay for arduino
    Wires, plugs, Switches etc
    Building material
  16. yellofella

    yellofella Member

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    Your list of materials looks pretty good for the sim you want to build. As i mentioned car battery's are a good starting point but your sim will probably only run for about an hour before the charge drops to a point where movement slows down and the battery's need 12 hours of charging each before they are good to go again. Have you got them wired in 12v parallel or 24v series to your motors. If 24v then just put one of your power supplies from the positive of battery 1 to the negative of battery 2 and you will have constant power and wont need to charge them so much. Make sure you know what you are doing before you try as car battery's are powerfull things full of acid.
    Also do you know what the rpm on the final drive of your motors are at 24v?
  17. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
    DC motor, Motion platform, 4DOF
    Why would I need car batteries? I have a power supply for each motor and a driver board for each motor.
  18. yellofella

    yellofella Member

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    sorry buddy. Didnt notice that gadget999 had commented, i thought it was you. Scrap my last comment.
  19. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
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    Ok haha had me worried there for a sec. Thank you for all the help. Can’t wait to start building when my parts arrive.
  20. Hale L

    Hale L Sim Racer

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    My Motion Simulator:
    DC motor, Motion platform, 4DOF
    I Got some 28 awg wore for the potentiometers. What gauge should I order for my power supply’s and the motors?
  21. Gadget999

    Gadget999 Active Member

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    the batteries act like large capacitors and absorb the regenerative braking

    the only need a trickle charge whilst the sim is operating