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Krazy Chair ready for smarts!

Discussion in 'DIY Motion Simulator Projects' started by EvanF, Jun 17, 2007.

  1. EvanF

    EvanF Member

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    Update: 16th March 08

    3DOF Rebuild.
    Build 1 of the 3 DOF chair was a good primer, it showed areas which needed working on. Based on the current motor specs here are the changes being made.

    1. Repositioned 2 front motors further forward of axis point. This sets the fulcrum further away resulting in a reduction of the amount of effort required to tilt the platform and it also slows the speed of tilt. Will mean a less eratic and smoother ride.

    2. Conrods have been shortened to tension up the central spring. Should help dampen the jitter when the motors are awaiting commands at central position after a returned washout. (There is no jitter when motors are actually doing something other than for example holding the '0 degree' position)

    3. Potentiometers are being relocated to rear of motors where the shaft spins at 40:1. Multi-turns have replaced the single turn. A 2:1 gear reduction is being worked on.
    Thanos AVR interface components are being sourced and a PCB organised. Although there is no firmware for a 3DOF system yet fingers crossed Thanos may find the time to program one. Otherwise it may still operate as an over-engineered 2DOFa !


    http://www.youtube.com/watch?v=_R50re8i82Y

    3DofRebuild01.jpg 3DofRebuild02.jpg 3DofRebuild03.jpg 3DofRebuild04.jpg 3DofRebuild05.jpg 3DofRebuild06.jpg 3DofRebuild07.jpg

    EvanF

    ########################


    Hi all,
    I have assembled the mechanical aspect for a motion chair which includes 24V DC gearhead motors. I'm working on the motor controllers now and also planning to assemble the Velleman USB I/O board when I get the chance. Once all that is done I'll be able to work on trying out the X-Sim software.

    cheers
    Evan

    [​IMG][​IMG][​IMG]
  2. egoexpress

    egoexpress Active Member

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    Hi Evan

    Wellcome to the X-Sim forum!

    I like your project as it needs just a little space. Its small enough for every room.

    If you want to use the X-Sim Software for your project, you should familiarise yourself with the X-Sim USO (universal serial output) port in the Force-Profiler.

    A member has driven his simulator with X-Sim and automotive wiper motors.
    http://www.x-simulator.de/forum/flight- ... -t223.html
    and another one with motor driven wires
    http://www.x-simulator.de/forum/x-sim-s ... .html#3046
    Perhaps you could exchange some ideas with them!

    Would you tell us please some details about the electonic and mecahnic part?

    Right now, we are up to build an interface for stepper drives with dynamic speed and accelleration control, but we are open minded for every other solutions ;)

    DC Motors, why not! ;)

    We would be pleased if you would get your simulator working with the X-Sim software. We really need some more people which use that masterpiece of software to make it even better. We need some feedback!

    regards
    ego

    EDIT: We could need some more english speaking members here.
    Thank you for making mention of us on your website ;)
  3. egoexpress

    egoexpress Active Member

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    X-Sim's automatic translator and spelling checker: ;)

    gearhead motor -> Getriebekopf-Motor
    accessory for the front glass cleaning -> car wiper motor
    torque -> Drehmoment
    -----------------------------------------------------------------------------

    I'd like to know the torque of your motors too.

    @sirnoname

    Perhaps the Hydranite controller could be interesting for him!?

    Gruss
    ego
  4. EvanF

    EvanF Member

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    Hi to both egoexpress and sirnoname and thank-you for your welcome.
    A gearhead motor is a motor with a gearbox built in.
    This particular one uses a planetary gear system.
    It has a gear reduction ratio of 40:1
    Shaft end the max RPM is 3200rpm / Gear end max RPM = 80rpm
    Torque shaft end 3.66kg/cm / Gear end Torque = 146kg/cm
    24Volt 7Amp 120W

    No it is not a windscreen wiper motor, I think you might be getting confused with CW's (a fellow kiwi enthusiast) system.

    The motors actually came out of an all terrain wheelchair.

    On my website in the video area there is a good example of their speed and power. But you if you are using Firefox web browser you probably won't be able to see them as they are embedded activeX objects. Let me know if you have problems streaming them and I will provide you with a link.

    Evan
  5. RaceRay

    RaceRay Administrator Staff Member SimAxe Beta Tester

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    My Motion Simulator:
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    Hi Evan,

    it´s a long time ago since i activated your account and see you here;-)
    Welcome at X-sim!

    After visiting your site wit the IE i can look at the videos. Not very mozillafriendly my friend;-)

    Seems that the motors of the chair are very fast and strong.

    Do you have already a video with all 3 engines on? I am very interesting to see all of them working together.

    What is a all terrain wheelchair, something like a caddy gulf car?

    regards
    RaceRay
  6. EvanF

    EvanF Member

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    Hi RaceRay,

    Yes it has been a while, being a prototype the chair took longer than anticipated to put together, but here I am!

    LOL when Mozilla presents multimedia as seamlessly as IE (for the mass population) then maybe I will look at crossing over, but that's not the topic of this thread - nice quip tho! ;-)

    I will see if I can find time this weekend to capture all 3 motors running. I'm avoiding running the chair until I finish the motor controller board. I am not intending to run the motor a full 360 rotation but perhaps somewhere around a 160 degree arc. I am a bit reluctant to flog the crank assembly too much while it is a wild ride. Once it has speed control then I will feel happy to try and run it to the ground.

    Yes I am very pleased with the speed and power output of the chair. It is a bit raw and harsh at the moment but I am working on a PWM motor controller and should be able to tame it soon - fingers crossed :)

    The All Terrain Wheel chair is an amazing buggy that can move forward in all angles. All 4 traction wheels counter rotate giving it amazing maneuverability. I wish I had asked for the motor controller for it when I bought the motors.

    Hear from you!

    Evan
  7. EvanF

    EvanF Member

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    Hi again,
    Just a quick update to let you know I am still working away, when I get a spare moment, on my chair.
    I have received some H-Bridge Drive units from USA which can switch 28volts at 25 amps controlled by logic switching. I have also successfully programmed a pic chip to control PWM forward and reverse and washout for the DC gearheads. Video's of this I have uploaded onto my Blog at http://www.extremevr.co.nz
    I haven't as yet soldered the Velleman but that is my next mission, oh and sorting out a way to attach a potentiometer to the output end of the DC gearhead for positional control.
    BTW what is the Hydranite controller you mention?
    cheers ears
    Evan
  8. EvanF

    EvanF Member

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    August Update: :D

    Potentiometers have been mounted onto DC motors and initial tests with a 12V/25Amp bench power supply is successful. The motors are rated for 24Volt 8 Amp and even at 12V at slow speed I cannot stop them with my hand. Not long now until I mount them back onto the seat and test them with 24Volts and under load. Heres some pix for those who are interested. Also a video of the motor and potentiometer in action can be viewed on my blog.
    cheers ears
    [​IMG]
    [​IMG]
  9. egoexpress

    egoexpress Active Member

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    Hi Evan

    Nice to read, that you have made some steps forward.

    The hydranite controller was the first attempt for a DIY stepper drive controller for the SimforceGT. But it failed for this purpose. Sirnoname mentioned, altough it couldnt be used for the steppers, it could be used as a double PWM motor control. But the devellopment isnt finished, yet.

    I think you wont be able to drive dynamic speeds with the Velleman. Its just an I/O card. Because of that you should, imho, go tronicgr's way.

    regards
    ego

    BTW: try it like this:
    geared_motor_with_pot_0.jpg
  10. EvanF

    EvanF Member

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    Hi ego,

    Thanks for your advice, I will trawl through tronicgr's post and look at how he pulls the FF data out of his computer. You are correct that we are both travelling down a similar path in regards to controlling DC motors.

    However mine is a 3 DOF so it may be a little trickier to configure.

    I like the idea of adding another axis for yaw too, which will make it even more of a challenge!?!

    Anyway this weekend I hope to assemble my 3 motor controller circuit together and bolt the motors back onto the chair frame. I haven't forgotten your request to see the chair in action with PWM control... coming soon :)

    [​IMG]

    [​IMG]
  11. tronicgr

    tronicgr

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    Evanf,

    Check out the presentation of my servo motor system:

    http://www.x-simulator.de/forum/tronics ... -t495.html

    You will find it usefull although it need some conversion to adapt to your 3DOF motion system...

    The way I see it, it needs some more calculations inside the microcontroller to translate the motion in such way to have all three motors cooperate to give you heave... And also a Heave input from x-sim software (currently outputs only x,y thru its USO).

    Regards, Thanos
  12. EvanF

    EvanF Member

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    tronicgr,

    Thanks for the heads-up of your presentation. I am impressed and it looks beyond my skills at this point. I think I will need to do a lot of reading to walk down your path! I am using picaxe to control my motors and I know you can pull data from the computer with them. But I am learning a lot by seeing what you have done, and I know I will learn a lot more going back over it again and again!

    cheers
    Evanf
  13. EvanF

    EvanF Member

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    Well since ppl are posting their working sims I thought I'd better update where I am at.

    I have the motion platform moving to pwm pulses. Max freq is 4khz and the feel is a little gravelly at this frequency but I don't think I have it set at full duty in the code. The washout is onboard at the mo.

    The pots on the motors (@10k) may need a bit more bracing from behind as I think they may flex a bit when I go for a spin. I have some pulleys as backup if bracing isn't effective.

    The floating charger and Sealed Lead Acid (SLA) cells are series and parallel wired to give me 26.9 volts at 18amps. But when the floating charger is on this gets boosted to 28.8volts. The H-Bridge drives are rated max at 28volts so I have tripled up 4 inline diodes (12 in total) and this has done the trick to reduce the voltage to 23.9v without trickle and 26.9v with trickle on. The diodes get very slighty warm and the H-bridges don't even get warm. Mind you I haven't gone hard out, just left the motors running and searching for '0' in the washout code for 30 minutes.

    Other than that I can start to look at some computer interface stuff as I feel the platform is more or less ready for it now.
    [​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG]
  14. EvanF

    EvanF Member

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    Hi sirnoname,

    Thanks for your compliment.

    The diodes get warm to touch but not hot. I chatted to Chris at Robot Power (makers of the h-bridge) and he reckons I don't really need to run the fans and the IC's shouldn't get hot, and if they do they would just shut down until they cool, so no risk if I tried. The fans are noisy and could affect gameplay. But good news for me, Chris said I can drive these up to 20khz (PWM) safely as the load is light.

    re edit: Do you mean I should just revise my first post all the time and not leave a trail for historical purposes? Following that thought perhaps someone could gather the information and collate a FAQ page might be a good idea so others could avoid pitfalls and false starts.

    plastic gear: do you mean the two 1:1 alloy cogs near the crank in front of the motor? yes there is a pot with 3 wires leading out. these like you say range from 0~255 with values >126,<128 as '0' (my term for horizon for washout purposes). I do get a little searching which backs up your +/-2 observation. I will post a video of the searching action tonight.

    I am not sure which way to go with the interface. Initially I was waiting on your hydranite board and now am waiting on Thanos with his new design board. Maybe while I wait I may try the velleman or use a parallel interface board I just found laying on my other bench. And I do like the idea of his servo control using (pcm?) pulses. Your thoughts on this would be appreciated.

    Ultimately I would like one board that can be used for flightsim/car racing/fps
  15. RaceRay

    RaceRay Administrator Staff Member SimAxe Beta Tester

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    Hi EvanF,

    very nice looking pictures you have. What about the motors and gears, when you sit down into the chair, are they moving duo to the bodyweight or are the gears strong enough to hold the chair in horizontal position when there is no power supply?

    I am still not sure which mechanical-setup i want to build - the Frexdesign/DOF-motionplatformdesign or the RnR/Thanos design!

    Imho, Frex and a motionplatform is the same, because the pivot is fixed and lies directly under the seat.

    Sirnoname ment, that it would be the best, when you publish all your new pictures, tecSpecs and all the other stuff in your first post, you have written. You can easily do it by press the edit-button beneath your first post!. So all the important information are on the first page, and able to see with one click and no long searches.

    regards
    René
  16. EvanF

    EvanF Member

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    Hi RaceRay

    Thanks!
    It is a planetary gearbox with a 40:1 ratio. On freewheel they do move slowly down if there is weight on the chair. I have tuned/adjusted each strut so the chair sits flat and the big spring has been adjusted (see the big solid cylinder and adjustable washer below spring) so the chair naturally sits with cranks at 180 degrees. Everything important on the chair is bolted and adjustable. (except for the seat rails on top dammit! they are spot welded on)

    I have posted a video on my website of the chair centering under power. On the video I push my hand down on the seat and you can hear the motors chatter as they fight against my hand to keep the platform centred. Washout is adjustable in the firmware. This is only a temporary control until Thanos releases his solution.
    http://extremevr.co.nz/media/torture-chair.wmv

    I think all the different sim platform designs have their merit.
    I chose the tripod design because I want 3 DOF and I am not as specialised just in car-simming, I want flightsim and fps-sim in the one chair too. I feel heave is important. I would like a 4th axis but maybe the next model.
    I think that the tripod design will be very fast in response time and transfer smaller vibrations a lot clearer with it's push rod action versus a swinging motion. The actions can be made dramatic with 2 motors creating a change in angle or for a finer motion just one motor moving the same angle. This is not very clear in the video because I was only testing by contacting a bare wire across the inputs so singular actions were clearer. Max = 100mm movements. Cranks could be extended but I wanna feel what type of effect 100mm movements transfering to the body are like. A very tight jap performance car?

    Aah ok, an ascending rather than descending post.
  17. egoexpress

    egoexpress Active Member

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    Seeing all this great work, I'd be very happy to see it in action!

    Unfortunatly I'm not very good in beeing patient....

    Do you know that most of us could not see the vids on your HP? Very Firefox unfriendly your page ;)

    BTW: Torture seat *g*
  18. EvanF

    EvanF Member

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    LOL, I luv Bill Gates :wink:
    Maybe I'll post them up to youtube for you :shock:

    Trust me, I am needing to practice incredible patience too, I can only manage to slip in 30 or so minutes a night into this, but I have 2 weeks break starting on the 24th so maybe sometime soon after that!
  19. RaceRay

    RaceRay Administrator Staff Member SimAxe Beta Tester

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    Evan,

    now, it is clear for me, why you have chosen the tripod design. I think it is not the easiest way to make a 3DOF because to control the up- and downward in conjunction with the x and z achsle, the movements have to be mixed and are not decoupled from each other. It is just like controling the head of a (RC)helicopter... :)

    At the same day, i have 2 weeks holiday, too :D
  20. EvanF

    EvanF Member

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    Hi Rene,

    Yes I agree, it will be a challenge to control 3 DOF Tripod. But IMHO the tripod is a more accurate representation of true motion freedom in 3 axis, with the centre of effort tighter focused on the platform.

    It's great how there are many different ideas and interpretation of concepts, it allows so many different designs to emerge and the world is not so boring!

    It will be interesting how it all comes together with the new profiler close over the horizon and Thanos new board's ability to translate more than 2 axis.

    Be it as it may I am making another board with a truth table to organise which actuator does what as I also am planning to activate actuators beyond the motion platform as well.

    Evan