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6 DOF from scratch

Discussion in 'DIY Motion Simulator Projects' started by Pierre Lalancette, Dec 18, 2016.

  1. speedy

    speedy Well-Known Member

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    My Motion Simulator:
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    Every thing depends on the final mechanical design you're going to have ... But .

    Ball Screw 1605
    is your magic key ... 16 is the rod diameter in mm and 05 is the pitch in mm .

    https://www.google.com.eg/search?q=Ball screw 1605&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjAq-bHq_jSAhVGShQKHb00AVMQsAQIFw&biw=1280&bih=680
  2. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    Thanks @speedy.
    I had read that post before. Can't believe I could not find the information back, but when you are looking with your eyes closed... Thank you to wake me up.
    16mm diameter and 05mm pitch. Really nice to know. I was already looking at those, since they seem quite popular around the forum.
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  3. SilentChill

    SilentChill Problem Maker

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    My Motion Simulator:
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    Someone is using 600mm can't remember who though and I think possibly someone using 1610 .
  4. judges

    judges New Member

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    It all depends on your setup and what you want to achieve. I just bought a 500mm 1610 (10mm lead) ball screw to build an actuator prototype. My motor has 3000 rpm and 1.91 Nm torque (5.73 Nm peak), which results in a (theoretical) linear speed of max 500 mm/s. A lead of 5mm would give me only half of that, which I figured might not be enough (I can always go slower). And it should still be able to move more than enough load.

    Calculators like this might help, if you understand all the input values (which I don't for some of them :p ):
    https://servotak.eu/tools/engineering_calculator
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    Last edited: Mar 28, 2017
  5. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    Thanks for the ling @judges, I might use it one day. But like you, I don't understand most of the values needed to make it work.
    I think I am gonna stick to 1605, as they seem to be able to shake a rattle most people around. We don't want an eject seat, but a simulator. ;)
  6. speedy

    speedy Well-Known Member

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    Thanks for the link @judges ... Nothing weird I think ... here is the LHS required numbers for a 1605 ball screw with 100Kg load and the normal requirements for actuators .
    there are some provided fixed No. where I guess they are standers .

    1.jpg

    what you need in results here is the motor power and the required gearbox output torque and ratio if there is one .

    Here is another one with the machining force = 5000 N :D => 3HP motor .

    2.jpg
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    Last edited: Mar 28, 2017
  7. judges

    judges New Member

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    Thanks, though I didn't say, I don't understand any of the numbers.. :p What I don't completely get, is "Acceleration time" and "Travelling weight" vs. "Machining force" (when you select the ball-screw-powered machine tool).

    "Acceleration time" is the time required to reach your desired linear speed I guess. But what's a meaningful value for sims? I also went with 0.1s, but dunno if that makes any sense.

    And "Travelling weight" vs. "Machining force": afaik force shouldn't be influenced by "System inclination" vs. weight will be influenced by system inclination. But in a 90° system, force and weight should be interchangeable, shouldn't they? Cause interchanging them gives quite noticable differences. Maybe I'm not getting something here...
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  8. speedy

    speedy Well-Known Member

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    @judges
    I think this is related to the final motor torque/power required for forward/stop/reverse ... to be able to produce vibs.

    I think travelling weight defines the minimum load for such given performance while adding the machining force is like adding a G-Force of a motion sim .
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  9. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    My Motion Simulator:
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    So, lets pretend that I take this motor:
    http://www.ampflow.com/three_inch_high_performance_motors.htm

    motor.jpg
    With a direct gear 1 to 1. I am not afraid to admit that I don't understand all the values of the motor and how to translate them to the calculation if needed. There is also the conversion from US to Metric. Still I tried.

    motor_calc.jpg

    I gave it a 45 degree inclination to put it in one of the hardest position for an actuator.
    I must admit, I don't know were to go from here.
    Last edited: Mar 29, 2017
  10. speedy

    speedy Well-Known Member

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  11. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    Yes, I have read the 13 pages plus of @wannabeaflyer2 project. My question is not about the design from here, but how to interpret the results of engineering calculator.

    Did I enter the right values? Are the results good? Is that motor strong enough?

    what you need in results here is the motor power and the required gearbox output torque and ratio if there is one .

    It's not informations I am used to read and it is a bit alien to me.
    Motor power = P1 = 0.451 Kw : Is it associated to the motor Kt (5.70), Kv (237 rpm volt)?
    Require Gearbox Output Torque: = T2 = 0.909 N-M : Stall torque 710 oz-in?
    Ideal Gearbox Ratio = I = 1.556 : Does it mean I need to gear down 1.5 or that the motor is 1.5 stronger than needed?
  12. speedy

    speedy Well-Known Member

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    For what ? For what type of motor controllers ? For which power supply ? Where is your sim dimensions ? is it Racing or flight sim ?

    Get out of the corner by making it more specific ... I thought you were going to use stepper motors .

    BTW... that motor is a 24V and you're using a 12V PSU .
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    Last edited: Mar 29, 2017
  13. speedy

    speedy Well-Known Member

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    Last edited: Mar 29, 2017
  14. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    Sorry for being all over the place. I'll try to recap:
    On post 1 I said: My motivation is "Elite Dangerous". So, I would say that I'm looking more the flight sim. But that would certainly not stopping me for using it with a car game or anything else, for that matter.
    The motor controler is a Sabertooth 2x60. I only have one for now. I mention it on post 36 and took a picture on post 42. I have tested SMC3 driver with success.
    I am using Arduino uno for interface with Simtool.
    My power supply are 6 DPS-500CB A PSU's (even tho I ordered Dell Poweredge 2650 Server 502W Redundant Power Supply DDS-500CB TH-00H694/J1540), but they behave the same. (post 21 to 33).
    I have not a single dimension in mind. I know, it is bad. But I wanted to build one actuator and go from there. I am quite heavy (almost 100 kg), so one actuator needs to be able to lift quite a lot.

    Yeah, I know. Stepper motors was my first choice at post 1, but I have found a post somewhere from @SeatTime that they were a bad choice. So I ask on post 7 what should I do? On post 9, @SilentChill suggested to exchange them for a Sabertooth. I asked the merchant and he agreed. This is why that now I have a Sabertooth 2x60.

    Trying to be more specific, I am looking for a simulator 6dof like @SeatTime or @SilentChill. Smaller base, compact seat with one axe at the back and two in front. One is made of wood and the other from metal. I have no idea which one I'll use yet. I am not the most manual guy, and it scares me a bit.

    For the actuator, I wanted to do something like the one from @SeatTime because it is shorter:
    Actuator with motor_gearbox attached.jpg
    But I see that he changed his design for direct drive motors now. "Decided to therefore go back to a direct drive setup (less friction losses - less to go wrong/maintain - no noise)" So, I will probably change my mind for direct drive setup.

    I also want to use 'Igus' Poly bush. I mention it here so I don't loose it (again).

    Yes, this is why I asked if we could run the PSU's in series, and @SilentChill confirmed it. (post 22 and 25)

    I choose that motor as @adgun suggest it to me at post 38. But since I know nothing about DC Motor (yet), I'm wondering if it is a good choice.


    That's it. I am to the point of building one actuator, using 1605 ball screw (that I will order soon) and some motors... :)

    No, I had not seen it. I will take a look at it now, but I will be using linear actuator for sure.
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  15. speedy

    speedy Well-Known Member

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  16. adgun

    adgun Active Member

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    Hi Pierre
    The E30-150 motor delivers 120kgf with +/- 350mm sec speed @32 amps( see performance charts)with 24 volt
    A 1605 ballscrew gives 100kgf with 1 NM
    Hope this helps
    regards Ad
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  17. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    Thanks a lot @adgun. i don`t have much time right now to make sense of it. But I will get to it soon.
  18. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    My Motion Simulator:
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    Ok. If I give a inclination of 45 degrees, a load of 120 kg and a gear efficiency of 0.76, which is a really bad situation:

    motor.jpg
    The motor require 0.662 KW, or 662 Watts.
    P=VI
    I=P/V
    I=662/24
    I=27.583 Amp
    This is well below the 60 Amp of my Sabertooth 2*60. Multiplied by 6 motors gives 165.5 Amps. That is a lot of power!

    Ideal gear box ration: 1.333. Still don't know if I would need to gear down or that I have over power.

    Torque: 1.144 N-m and 1.716 N-m (Newton Meter). 1.144 N-m converted gives 162.004050526032 oz/in.
    This is well below the Stall Torque which is 710 oz/in.

    So, if I am not mistaking, the motor is up to the task, but maybe my power supplies will find it hard to provide the needed power. Still, those are extremes conditions. Am I right?
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  19. speedy

    speedy Well-Known Member

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    My Motion Simulator:
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    You put 120 KG on one ball screw ? :confused: ... x6 = 720 KG total => ~ 1 Ton :D:D

    ==========================================================
    So first ... Let's say you have a total platform weight of 180 KG ... supported by 6 actuators beneath it that will give each one a share of a 30 KG each plus a safety factor of 10% so 33 KG or 35 KG net weight for each ...
    do some force analysis on this 35 KG and you'll find out the needed weight for each ball screw if not inclined .

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    Last edited: Apr 3, 2017
  20. judges

    judges New Member

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    Forget about that. You probably don't want to use a gear box. The ball screw is your "gear". So your motor shaft will be directly connected to the ball screw (1:1).

    The output value "Ideal gear box ratio" is just the result of your input values for "Ball screw lead", "Linear speed" and "Motor rated speed". The ball screw moves 5mm/rev, your desired linear speed is 0.35m/s, so you need 70 revs/second to get there (0.35 / 0.005). 70 x 60 to get rpm (=4200). You've entered a rated speed of 5600rpm, so 5600 / 4200 = 1.333. That would be the ratio required to get that exact linear speed.

    But the motor doesn't do 5600rpm under load. Have a look at the performance charts like @adgun suggested:
    http://www.ampflow.com/E30-150_Chart.png

    So at 1Nm torque the motor does 4500rpm. Which results in a linear speed of 0.375m/s.

    You don't wanna use stall torque for your calculations. Unfortunately the performance charts don't specify nominal torque (max continuous torque). You would need to ask the manufacturer. But I guess 1/4 to 1/5 of stall torque is a good assumption.

    But like @speedy mentioned before, 120kg load is "a little bit" on the high side... ;)

    Please correct if I'm wrong, but wouldn't the worst case scenario be like 2 actuators need to lift half of the payload (for e.g. just a pitch movement with a centered mass)? That would be 45kg per actuator...
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