A motion platform using Power Steering Racks !!!

[Jim NZ]

Believe it or not but another KIWI (New Zealander) has put his Kiwi tallent to good use.
Craig is getting a motion platform going using Power Steering Racks from cars and driving them with wiper motors.

Progress looks good and he has just got a website going to pass the info on.
Great pictures Craig !!

His site http://homepages.paradise.net.nz/cwarner/flightsim.htm

His video clip should convert the "unconverted" :lol: :lol:

Thanks for the info Craig.
JimNZ
www.jimspage.co.nz

[Roland]

Wow! Indeed an amazing setup. From the pictures I gather that Craig has been experimenting with different motion systems, but his latest setup really looks like a mature piece of work. It also shows that the cable pulley method can be used succesfully in combination with car steering units. The video shows nice motion response, this PS rack driven with windshield wiper motors really has promising capabilities.

For the people not familiar with power steering racks (like myself) have a look at http://auto.howstuffworks.com/steering2.htm and the following pages.

Great work!

Roland
www.simprojects.nl

[CWFlightsim]

Gidday,
thanks for the kind words.
Yes progress is good at the minute and finally the light is at the end of the tunnel, yesterday I sorted out the return to centre and finished the software, so today I will run it with FS2002!

[wannabeaflyer]

Hi Guys :D back again actually been checking this site out daily so i think the term lurker is the latest buzzword LOL:- Any chance of some overall specs on the steering rack used ,, Typically amount of travel and how this type of unit dealt with "Backpressure" to coin a phrase used by Jim 8) am intrigued by the cable and pulley method as i am always looking at different options to get around the problems we encounter trying to get our dreams off the drawing board and into reality. . How many Steering racks did you Use and i suppose linked to that question how many DOF's does this type of system produce, looking at your control wiring am i right in saying your going down jim's brilliant method of controlling the motor's would very much like to get some feed back on this info ... Brilliant Video by the way , just shows what can be done and how it can be done . :)

[CWFlightsim]

Gidday,
I used two steering racks one for roll and one for pitch. (2 DOF)
With the wiper motors connected, it eliminates any back pressure, you can literally jump up and down on the platform and not move it, I used cables because on the problem of transferring horizontal movement (racks) to vertical (platform) and it seems to work ok.
Although I copied Jims concept I made quite a few wiring changes due to me not needing to soft start. anyone interested in details of the rig, email me. my website is http://homepages.paradise.net.nz/cwarner/flightsim.htm

[wannabeaflyer]

Hiya CW Just to say thanks for the info all good stuff going into the mix :wink: You answered most of my request but still need to bug you for one more bit of info ok ok make that 2 bits :oops: How much travel do you get from your steering rack ..i mean i belive your only using one end of the rack so am trying to figure out how much travel is needed to get the Pitch / Roll angles Jim indicated in his project brief.... Now come the pushing my luck LOL any chance of a sketch of your pulley arangment ( again i figure you have set the steering rack output end as a push pull mechanism so you may have 2 cables per axis always maintaining tension at the actuator ??? just guessing here as i said any help would be greatly appreciated. betwwen Jim , Roland and Now Yourself my mechanical concept will be able to see the light of day .. Cheers CW and All The guys / Gals that contribute to the excellent forum .. come on you lurkers i know your there the hit counter says so :lol: send us your notions and we will put them in motion ...

[CWFlightsim]

Gidday, no need to apologize, dude, I am more than happy to answer any questions in the quest for motion we all share the same interest. The travel on the PS rack is 130 mm. I have made a crude diagram in power point (easiest and most convenient drawing program) it is on my website under platform diagram. I hope it is clear enough( hard to do in 3D)
Any other Q's fire away. good luck http://homepages.paradise.net.nz/cwarner/flightsim.htm

[wannabeaflyer]

Hi Cw Been scanning this website none stop hopping for an answer ....You Sir are a star , Thats the thing i think we take for granted gotta say major thanks for the info and your great attitude :D just seen the info and you confirmed my thoughts as to how you made your Platform actuators ..Will be going to see the Car Breakers this weekend about the steering racks .. Been working on jims concept for a while now but belive it or not i have had to go build a workshop in the garden to house my new baby when i build her LOLA :-0 a wee Bit Arse about face as we say in the UK , But The Little lady wont let me play with the Motorbike , Paraglider , CNC machine in the House any more LOL good thing is she OK'd the Workshop So been a Bit of a hold up while i get that done. Love this ideas Exchange thing just hope i'll be on the giving end soon to help the next guy out. Got one steering box A La Jim's design already but hoping Steering racks will be cheaper and easier to come by Fingers crossed .. Very Best Regards Good Buddy Cheers :)

[CWFlightsim]

Just a note for anyone out there, the motion platform works! Tested it today and exceeds all expectations! It has been a lot of work but completely worthwhile and I hope other people will go down the same "homemade" path!

[Rodney]

I have got to stay out of this forum! Great work, and information.

[CWFlightsim]

Hey, Rodney, why do you need to stay out of this forum, I am intrigued!

[CWFlightsim]

New videos added today http://homepages.paradise.net.nz/cwarner/flightsim.htm

[Jim NZ]

Craig, you little beauty !!! It works !!! And so it should !!!
Thrilled for you Craig, and I can see your beaming smile from here. There is no bigger thrill than motion with FS.
Just goes to prove that Kiwi ingenuity works and you dont need to spend megabucks just to make something move.
Video's are great and tell the whole story.!!!
Just some fine tuning and tinkering to get the speed right etc etc and thats a really fun bit because it is already going.

Marvelous Craig.

Had a wee chuckle at Rodneys comment ... hehehehee .. yea its like a bloody desease (motion) ,, it first starts off as a curiousity ,, then an interest, then a bloody obsession !!!! Rodneys at the curious stage ,, give him a few months and all **** will break loose !!! hehehe

Anyway, congradulations Craig .. marvelous ,, thrilled for ya. :lol: :lol: :lol:

Jim NZ
www.jimspage.co.nz

[Rodney]

CWFlightsim wrote;

Hey, Rodney, why do you need to stay out of this forum, I am intrigued!

Because I'm afraid that I will stop doing other things on my project and do what you have done. Remarkable by the way. And affordable too.

[CWFlightsim]

Yeah Rodney, I actually did the same thing, I had no intention of building motion, due to the lack of programming skills, and then I read Jims page and everything else got put on hold, however, the platform is complete and running now and I am continuing on with the other stuff. I am glad I did it that way in the end! Keep up the good work, great website by the way!

[wannabeaflyer]

HI Cw
been looking at Ebayand the loacal DIY stores for Pulleys and cables along the lines of your mechanical assembly . did you have any preferance ref size of pulley / Cable used for your project . been to the Local DIY store and found that they had Nylon sleeved 3mm & 4mm Steel braided cables and fittings to secure the ends eye bolts etc . the breaking strain was listed as in excess of 300Kg which would seem to meet our needs , they also had Pulleys but the quality did not seem to me to be up to the job seeing as the breaking strain of the Cable was so high.. anyways the Pulleys were 50mm diameter but not running on bearing s just pivot pin :cry: where did you source you bits regarding these items any specs or pictures would be great. Also looking at mounting my Steering racks at 90° to each other mounted under the centerling of the Universal joint to try to remove the need for pulley change of direction. and maybe using both end of the steering rack in a sort of Push Pull arrangment. Any thoughts on this idea ? :D Cheers guys

[CWFlightsim]

Gidday,
I have 4 mm stainless cable with an eye hook on one end. The pulleys started out as 38 mm die cast from the local hardware store and I just replaced the pin with a bolt, however the mounting point was weak and I replaced them all with 50mm steel ones and secured everything firmer.
Good idea about the 90 degrees, I mounted mine as I did because I thought that the width of the rack compared to the platform may have been and issue. I cant (in hindsight) see any disadvantages and several advantage to mounting the racks 90 degrees and should of probably carried on with that plan. I also only used cables because I was lacking in ideas to send the motion from the horizontal rack to the vertical platform, I was originally going to mount the whole lot in a cradle and raise the COG but cost and time got in the way. But as it happens the extra pulleys dont affect the performance at all and it works fine.
The push pull may be OK. I only used one end of the rack and made a plate with a hole in it which fitted in where the inner tie rod end is and cut off the tie rods.
My only comment is that the strain on all the mechanical parts, cable, mounts, pulleys etc, is very high and took me by surprise, please over-engineer everything connected to the motion to avoid not only breakages but everything stretching and moving.
Happy building!

[wannabeaflyer]

Hi CW . Just to say thanks for the info its been a major help still trying to source more bits but before long my assembly kit will be ready :) between your ideas and Jims Great information website and pictures i am even more confident i can get this done , Was never gonna be easy but you guys have put this type of project into the reach of the Average Joe, so just my way of saying BIG Up Thanks and Appreciation for all the help and feedback and just hope soon i'll be in a position to give some Back ..Cheers Guys :D

[bishoff7]

Hi to all
Great Job craig you should be most proud of that simm it is a credit to you
Iwas wondering how you got away with no soft starting
Regards. Bish

[CWFlightsim]

Gidday, I think it may be due to the hydrualics softening the start, however it is early days, and to be honest I may still have to go down that road, I am using resistors at the minute for washout, with a few issues, but generally I have a reasonable feel so far and I am in the software/hardware tweaking and tuning stage now, will keep you updated!
Happy motions!

[pk_volt]

Hi Everyone

I'm new here.

Anyways, just a bit about myself. I recently graduated from a mechatronics program in a technology institute. Having gained so much knowledge, I figured, why not put it to use. This is when a motion simulator comes in. I've always been fasicanted by simulators, which was the whole reason why I went into a mechatronics program.

Judging from some of the work people have done around here, I guess most of you have already surpassed my knowledge. :wink:


Anyways, I just wanted to add a few links to some motion simulators out there just to get some more ideas of possibilities flowing.

unfortunately, this project was discontinued becuase the system wasn't stiff enough, so it always oscillated. Looking further into their provided information, they seemed to have integrated some complicated feedback system

http://www.cadsoftusa.com/people/kls/fltsim/index.htm

here is another 6 dof simulator using Festo's Msucle fluidic system

http://members.shaw.ca/bokinator/X6.jpg

sorry, I don't have the link to their simulator as it seems to be down

[Matt Olieman]

pk_volt, thanks for the info (links) and welcome aboard. I think we're always open to new and old :) ideas. Thanks for sharing the links.

[CWFlightsim]

Gidday fellow simmers, I have just given my web page a bit of a face lift, some new photos and some more info, the motion system is working great and
I am making panels at the minute so will include photos as I go, the light is at the end of the tunnel now!

http://homepages.paradise.net.nz/cwarner/flightsim.htm

[Roland]

Hi Craig,
Good job on the website, lots of good info available there.

Keith is currently tweaking his portdrv utility, lot's of posibilities! so we're busy testing and tweaking the roll axis drive of the platform drive. Since I use software driven DA converters that drive the roll and pitch servo, there are lots of options to get the best results.

In my experiments I started with the roll angle movement derivative (roll drive based on New - Old value), and when I did tests with the Extra, it was maybe OK, (Red Bull Race effect) but for cessna's and bigger planes, you hardly have the jolt when starting a roll, but your head will give you this funny out of balance rotation feeling during the roll from 0 - 30 degrees. I found that when adding the actual roll signal to the drive, it simulated this feeling, but I needed to do something to get the back to center washout.

As far as I can tell, you and Jim are using the following system: When the readings new - old become > 1 you start to move the platform in (say positive) direction with a certain fixed speed. When new - old become < 1 you enable the back to center drive.

In my case I could make the platform speed dependend on the the value of new - old. To avoid overdrive when the platform drive seems to come close to the extremes, this positive roll drive has to gradually flatten out.
I tend to believe that this roll action does not need to be fast: Maybe the actual roll signal to the servo drive will do.

Then when new - old becomes 0 we start the washout back to center. I think the start of the washout has to have soft-start, so it is not a sudden motion back to center, and the washout movement has to be slow, (how slow?) as the occupant should not notice the washout.

Washout going completely back to zero? --> Actually in a steep turn (like a glider) I found that having the platform still slightly tilted to one side is helping you to get that "being in a turn" feeling (together with pitch up for back pressure)

Do you have any advice on the above? Roll speed, washout speed, start and stop of washout, combination effects, ect.

Thanks!

Roland

[Jim NZ]

Hi Craig,
Just checked out your new, updated website and its brilliant.
The wiring panel has certainely grown since the first biuld !!! but it goes to prove, start simple, get it going, and develope from there.

I had a quick look at the gwbasic code and you certainly got the hang of that pretty quick .. well done !!

I havent yet been able to view the diagrams as I cant see a ppt file with anything I've got... I would guess I'm not the only one with this problem.
Any chance of a doc or a jpg of them ???

Good on the old Kiwi's eh?? (Might have to make Roland an honary Kiwi though ??)

Anyway, great stuff Craig.

Jim NZ
www.jimspage.co.nz

[CWFlightsim]

Gidday, fella's
Hey, Jim, I have changed my PPT to JPG for your perusal.
Also, if Roland can tell us what to do with a piece of number 8 fencing wire, we should make him an honarary Kiwi!
Roland, your return to centre,
you are right, when 1 becomes 0 or when the aircraft hasnt changed roll angle, my roll relay switches off and allows the return to centre relay to take over and allow the motor to move in the opposite direction until the centre microswitch stops it all, in other words the platform will always want to be in the centre unless the PC has other ideas by sending a roll signal. I have my soft start wired up so that the power that makes the sim R.T.C (washout) also changes (via a relay) the pot VR1 on the softstart unit.Therefore with 3x 5K pots and two DPDT relays I can control the activation speed and RTC in either direction (Made for that fat co-pilot) or only me on one side of the sim.I set the speed of washout so it is slow enough that the brain doesnt notice it, the only unfixable problem I have is that there is no 'soft stop' and you can feel when the sim stops moving. I deal with pitch a bit different and have wired in a return to centre inhibitor to stop RTC over a certain pitch angle, I feel that on climb or steep dive you should be 'back in your seat' or 'hanging by your seatbelt', I am still experimenting on the proper angle I am on 13 degrees down and 10 up at the minute anything under that the platform will return.I like the idea of not returning completely to centre but with no feedback I cant really impliment that, I now would like an interface that is more than 8 bit, I am fast running out of channels to use as ideas come to mind. I reackon I have probably halved the sim speed since it was first run, the brain pick up the movement just the same and it is more controllable, I also am not getting airsick any more, that I feel is a good indication that the motion cues are what my eyes expect to see.

Cheers.

[Roland]

Hi Guys,

First thing that comes to mind is fixing that "give" in the roll-pulley key-way: number 8 fencing wire should just do the trick.

Craig, thanks for the explanation and hints on the roll and pitch. It's a pretty clever system you have worked out with the various softstart actions. For the return to center soft-stop, maybe a second set of microswitches on both sides before the center switch, coupled with a resistor to slow the motor somewhat. Or maybe a very big capacitor across the switch? Just thinking out loud. Have a look at my power up softstart relay sequence.

I have the feeling that we all tend to overdo the motion in the beginning of testing, then scaling back to get things more realistic. Can you give me some numbers on the platform roll speed (seconds / degrees) during the change in angle, and the washout? This could give us some clues on what target to program for.

Thanks,

[TronicGr]

Hello to all, I'm building a motion cockpit based on the Joyrider design. Right now I'm in the process attaching the motors (car wiper motors).

Here is an early weight test video:

http://www.ptyxiouxos.net/greekbotics/e107/e107_files/public/1161605702_7_FT1070_test_ride_mfs1.zip

I'm a beta tester of the Portdrvr (dll) by Keith Daniel and right now I'm testing its modifications to add some washout. This is the software I'm going to use to move my cockpit soon. Roland is with us on this too.

Here some interesting videos I took when tested the code with some small hobby servos:

http://www.ptyxiouxos.net/greekbotics/e107/e107_files/public/1161601155_7_FT1070_washout_cesna1_test.zip

http://www.ptyxiouxos.net/greekbotics/e107/e107_files/public/1161601155_7_FT1070_washout_boing737_liftoff_test.zip

Regards, Thanos (Greece)

[Roland]

Hi Thanos,

Welcome to the motion forum! Your videos are showing real progress.
Some explanation for the others:

Thanos and I are the testers for the new version of Portdrvr utility. Thanos has a Basic Stamp unit that drives two servos to prove and test the concept. The data comes in via serial link from the FS PC. As you can see, Keith is aiming at getting two very speedy output data streams, pitch and roll, that also contain all needed cues and washout effects to drive a servo based platform with position feedback. Not an easy task to be sure, but very interesting!

Roland

[CWFlightsim]

Gidday Thanos,
Great videos, I like the servos and programs ability to pick up ground bumps, and acceleration, it looks really reponsive and fast, I would like to see the program again after you and Roland have tweaked and tested it,

Roland I have done a bit of a measure up, the figures are as follows:

my roll axis pivot from centre (each side) is 530 and pitch is about 580, these are based on the gears ability to lift the mass happily without the P/S pump going. I can (and did ) speed it all up by moving the pivots in, but I felt sick, so I guessed this wasnt right, the angles are between 18 and 20 degrees pitch and roll and it takes about three seconds to move from centre to full and about 7 seconds back to centre on washout, the rack movement is about 140 mm. One thing I have observed (IMO)is that the speed of the sim is less important than the movement (say roll) acceleration. In other words if the plane is increasing or decreasing bank the sim should be moving and it would appear that speed really plays a small part in the sensation (to a point)

hope that helps,

Cheers.

CW

[Roland]

Thanks for this info Craig, very helpful.

Progress is good. Keith has lots of good ideas and new versions every other day, and Thanos is pretty sharp on what's going right or wrong. I can check the actual motion feeling, so with the three of us, we make a good team.

Will keep you updated how things are going.

[CWFlightsim]

Gidday Roland,
Thanks I'd like to see the prtdrvr stuff, when its done. Oh by the way, great idea with the No.8 wire, welcome to NZ! passport is in the mail!
Mounted the projector today and made the rear projection screen, tommorrow will see the complete visual system complete, screen size 2000 x 900 mm. fills the front screen.

CW

[wannabeaflyer]

Hi Guys , Just another of my should know the answer but not seeing th ewood for the trees type o thing .. Trying to do a mock up of my platform before metal cutting and welding starts after xmas...any tips about locating the cockpit elements i.e Seat , Lcd Monitors Preferably and any othre items not forgetting the bulk Me --- am assuming again that ideally most of the weight ( Bulk + Car Seat ) LOL:-) should be positioned more or less over the Pivot point of the Universal Joint ( im Guessing here) and in doing so will decrease some of the effort required by the actuator mechanism ( whichever one is Fianlly Fitted ) is there some sort of Calculation formulea out there which would allow me to Punch in some weights and Distacnce to Pivot and so allow me to in thory at least work out the likley load on the actuators ??? as it stands i wll be trying to get LCD's for my Instument display,GPS, Etc and already have Opencockpit Interface Boards But they wont be of any considerable weight in comparsion to the Bulfk Factor ( Trying to keep Platform Weight down to again ease the Load on the Drive units) Any help guys will always be appreciated

[wannabeaflyer]

Spelling and grammer mistakes galore Sorry guys the brains ticking over faster than the 2 finger typing is capable of handling D'Oh :-) well thats my excuse anyways but hope y'all get the drift of my request Thanks

[Roland]

You are right in wanting to get most of the weight close to the pivot point. Ideal situation would be to have the platform just balanced with all gear (incl pilot). Depending on the weight of your gear (cockpit controls, frame, display, ect) and yourself, you should should be sitting with your knees around the pivot point. This is how it is in my setup. http://www.simprojects.nl/diy_motion_platform_ii.htm (I'm about 70kg, gear in front is 1x18" LCD for dials view and 3x15" LCD for outside view, + pedals, transducer, switchmode power supplies and other stuff. PC's are outside the platform. My setup is quite well in balance. The rubber inner tube underneath will also help self centering.

For balancing calculations, it's basically an addition of (weight)*(distance from pivot point) of the various components, yourself being the biggest influence. The sum on both sides of the pivot point needs to be equal for balance. It is advisable to make the seating position slightly adjustable for fine tuning.

For the speed calculations, I have done some experiment with platform accelerations. Rough, but in the ball-park. http://www.simprojects.nl/platform_drive_calculations.htm
Although I find now that the fast acceleration is not absolutely needed for our type of motion platforms. (or only to be able to mix in the ground bumps and turbulence stuff)

Hope this helps.

Roland

[CWFlightsim]

Gidday, long time no see, just a couple update photos for those of you that are interested, have got two LCD screens going now and just working on getting the next four going. Using dual head AGP card for the two front and looking for a quad head PCI for the others. Motion is working good, and the cockpit is enclosed now, I have also upgraded to FS9, much better scenery and weather than FS2k2.
Have a merry Xmas all!
Cheers

CW

[CWFlightsim]

Sorry, couldnt upload photos, goto http://homepages.paradise.net.nz/cwarner/flightsim.htm

[Matt Olieman]

What a way to go.... Looks fantastic and fun :D Love to take a ride with you....

Thanks for the pics....