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6 DOF from scratch

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

  1. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    My Motion Simulator:
    DC motor, Arduino, 6DOF
    That spring thing is quite nice and simple to set-up. Thanks a lot. I will use it, it's almost sure.
    • Like Like x 2
  2. haribole

    haribole New Member

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    Hello Pierre

    Thanks so much for sharing your build.

    Wondering about the Sabertooth DC Motor controller, since the max current draw of the motor is only 17A , do you still need the dual 60A controller? Can a 2X32A not be used?

    Thanks
  3. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    Probably, but reading on this forum, I found out that there is a lot of peaks that goes beyond that calculated 17A. I have no experience to back up my saying, but it comes from experienced builder. The changes of directions on the actuator may draw more current for a short period of time, and if many actuators change at the same time, it can go pretty high. I have read that some power supply were tripping from it, and other build have relay up to 70 Amp per motors (so I bought too). I also read that some people found 2x60 more stable than 2x32. But again, I have no experiences to backing up my big mouth.

    So, since I hate taking chances, I decided to invest right away on the high end. It may be overkill, but it's also peace of mind.
  4. adgun

    adgun Active Member

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    Its got more to do with voltage,
    U=IxR
    a 720watt 12 volt motor ask 60 amp current, and a 720 watt 24 volt motor ask 30 amp
  5. RandomCoder

    RandomCoder Active Member Gold Contributor

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    The issue is as @Pierre Lalancette described, the back emf which a motor can induce will potentially destroy electronics. This back emf is induced because the inductance of the motor coils opposes change. With our desire to frequently change motor direction, this can subject the electronics to very high current spikes on a regular basis.
    Here is a snippet taken from this site https://opentextbc.ca/physicstestbook2/chapter/back-emf/ .....
    Consider, for example, the motor coils represented in [link]. The coils have a 0.4ohm equivalent resistance and are driven by a 48.0 V emf. Shortly after being turned on, they draw a current I=V/R = (48V)/(0.4ohm)=120A and, thus, dissipate P=I^2 R =5.76kW of energy as heat transfer. Under normal operating conditions for this motor, suppose the back emf is 40.0 V. Then at operating speed, the total voltage across the coils is 8.0 V (48.0 V minus the 40.0 V back emf), and the current drawn is I=V/R =(8V)/0.4ohm)=20A. Under normal load, then, the power dissipated is P=IV =(20A)/(8V)=160W. The latter will not cause a problem for this motor, whereas the former 5.76 kW would burn out the coils if sustained.

    The equation here is over simplified but hopefully you get the idea.
    • Informative Informative x 2
    Last edited: May 27, 2018
  6. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    My Motion Simulator:
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    I have new parts! They are the end parts of the actuator where to screw the joint. They are nice, they fit right in and my build cost went up 100$. As far as I know, they worth every penny.

    IMG_1916.JPG

    Also, I finally got back to designing the potentiometer support with the added limit switch. Why was it so long. I was scared I could not do it, and for a reason. It is quite complicated (well, it was for me).

    IMG_1909.JPG

    My first time using support for bridge structure. Quite intriguing.

    IMG_1910.JPG

    Scary to remove, but not that hard.

    IMG_1911.JPG

    But of course, I made it too tight and nothing fits.

    IMG_1912.JPG

    Even with some cut away, I could not make it fit. It has to be redone. I was quite discouraged.

    IMG_1914.JPG

    At least, the switch part was working, even if it needed a bit more clearance for the connectors.

    IMG_1915.JPG

    So, it was back to the drawing virtual table. I was sure I had to start it all over, but no. I could make the adjustments and add some strength to it (so i think). I is printing right now. I'll see in a few hours if I am still discouraged. :)

    part_v012.jpg
    • Like Like x 3
  7. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    My Motion Simulator:
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    Wow! Am I happy?

    I was able to get it right the second time around (if you don't count all the tests I did for each individual parts). It is tight, but it fits.
    As usual, I put the walk of shame beside the finished product. But I should say the path of experience.

    IMG_1918.JPG
    • Like Like x 2
  8. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    My Motion Simulator:
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    The top part. Still needs some adjustment here and there, but I am getting good at it.

    IMG_1919.JPG
    IMG_1921.JPG

    Now I need to design the middle part, to replace my puck... That I still thing is a great idea... But I've been recommended to change... Social pressure...

    If I keep on doing one part every weekend, I may finish this by 2010. Wait! What's the year?
    • Funny Funny x 2
  9. Flymen

    Flymen Flymen Gold Contributor

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    My Motion Simulator:
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    hey, i see you again working on the project again!!

    The power supply are on the way for me !!
  10. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    Yeah, me too, I'm waiting for parts on the power supply. Someone working on repairing boats told me he gets old, but working batteries that he has to pay to get rid of. I hope he can get me two deep charging 12 Volt batteries.

    During that time, I only miss the middle design off my actuator. But it will be hot this weekend. It sounds like a water park day. I may miss a design deadline task because of that. But it's so fun. :)
    • Like Like x 1
  11. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    My Motion Simulator:
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    One of my middle part of my Actuator is printing...

    But since it was not good enough today to go to the water park, we wondered around town today. Look what I found in a pawn shop, waiting all that time for me.

    IMG_1922.JPG

    I am a lucky son of a beautiful mother.
    • Like Like x 2
  12. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    Sounds like it was meant to be ;)
  13. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    DC motor, Arduino, 6DOF
  14. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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  15. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    My Motion Simulator:
    DC motor, Arduino, 6DOF
    Thanks Noorbeast, This is probably how I find it back, after many wondering around the site.

    I cut my cabon tube. I'm better at it and I know how to do it more straight. Warning, I read somewhere that carbon tube powder is highly dangerous. Don't breath it.

    IMG_1926.JPG

    It fitted perfectly into my part. But this is when I found out I was way off in my measurements. Not enough support, the part will need to be longer. Redesign, again.

    IMG_1927.JPG

    Still, I made the setup so I could make it moves. Windows made me wait more than 3 hours for an update. :confused:

    IMG_1928.JPG

    My v-weel attachement are way of, they need a better design too.

    IMG_1929.JPG

    Using the attaches for the strap cracked my part. Redesign.

    IMG_1930.JPG

    For the bottom part, the limit switch is on the wrong side. Will have to redesign.

    IMG_1931.JPG

    The top part is on the right side, but how it is hold in place need to be more compact. It was already called for a correction in the design.

    IMG_1932.JPG

    Here it is in action. There is a lot of vibration, but the carbon tube is way to long and it attached poorly. But, I could see it in action. The weight is unknown. The motor is driven by a simple computer power supply at 12 Volts. The final will be drive at 24 Volt. It did not break a sweat.

    • Like Like x 2
    • Optimistic Optimistic x 1
  16. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
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    I really appreciate your calm matter of fact approach...oh well just another redesign!
    • Agree Agree x 1
  17. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    My Motion Simulator:
    DC motor, Arduino, 6DOF
    I have not done much on my build this week, due to incredible weather outside, but...

    Last week, I have redone the design of the ball screw part of the actuator and printed it. But my Solidedge desing was warning me about something, but I could not any problem. I decided to print anyway. Result: a sudden jump in the print.

    IMG_1941.JPG
    IMG_1944.JPG

    But it appended only once. I decide to break it and fix it for test. I know what went wrong and I can correct the design later.

    IMG_1945.JPG

    I had bought rod and nuts, since no screw were long enough for my piece. The springs are for the limit switches and the bearing ball for a test. I also bought the 3 helm joints that I will need later... much later...

    IMG_1943.JPG

    It worked. You can see were I will use the spring with a rod to activate the limit switch. How I will use nails to attach the strap in the middle and pass it over other nails and tie everything up with tie-wraps. The v-wheel works great now against the carbon tubes. They are much stronger than the old model.

    IMG_1946.JPG
    IMG_1947.JPG
    IMG_1948.JPG

    Installed to test. Worked great, even though nothing is fixed permanently.

    IMG_1949.JPG
    IMG_1950.JPG
    IMG_1952.JPG
    • Like Like x 2
  18. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    My Motion Simulator:
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    Christmass, Christmass, Christmass!

    I totally forgot to put the auto focus on my camera, but, you get the picture. (Ha! Ha! Pun intended!)

    Got 2 new carbon tube because I was not sure to do all 6 500mm actuators with only 4 1m tubes.

    IMG_1956.JPG

    What could be in those boxes?

    IMG_1957.JPG
    IMG_1958.JPG

    My 5 other Ingus bearing (ouch$$$) and a grey pla roll with a orange pla roll. Reading other thread, I would have probably tested eSun PETG. But at the same time, I had next to no trouble with my amz3d pla so far. If it's not broken, don't fix it.

    IMG_1959.JPG

    I put the auto-focus back on my camera. ;)
  19. Thanos

    Thanos Building the Future one AC Servo at a time... or 6

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    My Motion Simulator:
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    If the G27 steering wheel is not working well, remember you can reuse them!!

  20. Pierre Lalancette

    Pierre Lalancette Sir Lalancelot Gold Contributor

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    LOL! What is that little steering wheel?

    So far, with the right driver, it's working really fine.