cessna platform

[kermit]

Hi, I have started to build a platform for my real Cessna 172 cockpitsection.
totalweight including pilot approx 300-350kgs cg will be nearly zero(-/+ 7%) balanced when horizontal)at 30 cm from ground
For now I have a platform thats made out
2 rectangular constructions 1600x1200mm made out steeltubes 50x50x4mm
and connected to each other with a crosslink to have bank and roll-movement(maybe in future I want to have Heave).
I have obtained 2 liniar actuators each with the following data
12volts 20 amp
speed 10mm/sec stroke 300mm 2200newtonmeters.
I can build a controll box with sufficient power for the actuators.
I`m looking for a PLC and motorcontrollers for the above, wich doesn`t cost me an arm and a leg.
Looking for a pricetag off around 400 euro max(800 $).
any ideas?
greetz Henk (Netherlands)

[jirehone7]

Hi Kermit, I am starting mine (C172) next week. Absolutely no idea on how to or what type of motors to use.
Talking to a electrical guy who has no idea what's a flight sim. Could you PM me some pictures.
I am trying out a pitch and roll motion initially. I also intend to make a wooden cockpit to cover the platform
but unable to get a jig diagram of either a C152 or C172. I am only seeing pictures but no measurements as
to exact jig.Replies appreciated.This is one of the best Sim forums where the 'family' is so helpful.
Thanks to all.

[kermit]

As soon as I have found my camera , I will make some pictures.
the best way to start is knowing how big your platform will be ,
If you surf this site you will find all sorts of measurements(If you own a real cockpit you already know)
during the build you can note all the weights you using or you can weigh when finished.
To know the CG the simplest way to do so, is to put the platform on a little steel profile and shift the platform until it tumbles and finetune shifting
until you reach a horizontal point .
When You found the first mark then this is the place for mounting the crosslink in that direction,
you can now find the mark for the other side left or right
You have to be seated during the steps on shifting.
If you make a cross with the found marks you now have the correct spot for mounting the crosslink.
Yes its crude but its the quickest way.
Then you need to know the forces to turn your platform.
But you can figure them out ,if you know the above.
Please contact me ,when you have all the date.
I then can calculate the motors you need.
greetz

[Roland]

Hi Henk,

Before buying motor controllers and PLC, I'd think you first need to check how you will do your interfacing from FS to your controlller.
If you are using Ian's BFF driver, there are some options, check his site. http://buggies.builtforfun.co.uk/Sim/hardware.php. I think his MD03 drivers should be able to drive your actuators.
Note that 10mm/sec is rather slow: for 300mm it would take 30 sec from one extreme to the other. I'd say that for pitch and roll, 2~3 sec from on extreme to the other would be OK. For nice dynamic heave motion, the faster the better: My #III actuators speed is about 600mm/sec during a fast step.

Roland

[kermit]

Hi Roland,
Yes ,I was(still:grin:) thinking of Ian`s controller,
But the motorcontrollers are asking 24 to 36 volts current, can I use 12 volts instead or do I use a 24>12 volt 20 amp converter directly after the motorcontroller.
The speed is a bit slow , but because they are 224 kgf ,
Your calculation is based on mounting the actuator on the outsideparimeter of the platform
But placed nearer to the crosslinkcolum,so therefore the angle(smaller travel needed) will be greater thus faster from the(offset) point I`m sitting.
I have to consider the lesser force it can hold/travel then,but I have more then enough force.
and because I`m flying a Cessna not a F16 bank and roll doesn`t have to be at great speeds .
Until I reach a desired speed I can shift the actuator around for trial and error , after wich I weld them to the contruction.

Also I have talked to our manager, I can play with gearboxes and motors /frequentie inverters.

I was thinking of 230volt 1,5-2 kw 1500 rpm 1ph with a MVF 63 or 86 gearbox i=100 ratio
It will give a output speed of around 115 mm/sec at 500/550kgf (MVF 63= 350 kgf),

If I change the i or put on a second stage gear it can go much faster but with lesser force,(speed for force), but that would be no probleem as the unit will have an overcapacity for now, I could drop more then 40 % without any problem.
I Can/have to place the unit directly under or near the crosslink colum and then connect with a torque arm(250mm).

But I can`t find motorcontrollers and a plc that could handle the data for now,
I have looked for a commercial package but that would set me about 3000 euro back.

I know you used 110 volt motors ,how did you overcome the motorcontroller data.
Could you built something for the above motor/gearbox systeem or for the motor alone or could I use a commercial(not to expensive)unit.
If so I could use the motor and mount a splindle actuator.

For the future I was thinking of a springloaded or rubberised heave construction within the crosslinkcolum to have a sort of slew in the movement and not a cold up down movement.

But first I have to sort out the bank and roll,
Now I know why it takes time to make a reliable platform/simpit;);)

As said earlier I`m more a mechanical then a electrical guy.
greetz

Note my platform has been calculated for up to a loadweight of 1200 kilogram or about 2900lbs enough for a B737:grin:

[Roland]

But the motorcontrollers are asking 24 to 36 volts current, can I use 12 volts instead or do I use a 24>12 volt 20 amp converter directly after the motorcontroller.


In this thread http://www.mycockpit.org/forums/showthread.php?17985-New-3doF-platform-construction Ian says that his motor controllers work correct with 12V input, so I think that should be OK for your actuators, provided they are permanent magnet DC motors. That would be by far the cheapest solution.

If you are going for 230V ac motors, (that require dedicated motor controllers) you may end up with incompatible BFF data to motor controller link.

My system uses 50V DC motors, but I run them from 36V, at which the forces are already scary enough. I use Ian's data with a home-build serial to DAC system.

[kermit]

Hi Roland they are indeed permanent magnet DC motors,

I use Ian's data with a home-build serial to DAC system, well thats beyond my understanding about electronics.
As for forces , I`m used to play around with forces up to tonnes of pulling and hoisting.
So 500 kgf is only childsplay :D:D just kidding.
I`m of an age that has experienced the old kick in the butt, when playing with safety during mechanical lessons at school,
without even thinking of complaning to my parents or head of school .
So safety to me, its like breathing air.
I have looked on the Phidgets site but again only stuff for up to 12 volts.

greetz

[IanH1960]

Hi Kermit,

Sorry gents - I managed to miss this post somehow - must be the new site layout!

Got your email Kermit.

The MD03 motor controller will work with 12V, the problem is it is limited to 20 Amps and I doubt if 12x24=240 Watts will be big enough for what you are describing.

You asked about the command format I use. The 40SPU-1 card communicates with the MD03's using the I2C protocol and it writes data specific to the data registers on the MD03 that control speed and direction, so I doubt if it could be used to instruct other motor controllers as it stands. However the I2C specs for the MD03's are published by the manufacturer if your controlls colleague is able to mimic its I2C setup.

If your colleague had a particular data format in mind for his inverters I might be able to add an additional output to the card that he can read. Perhaps a simple TTL level serial output? Although this kind of mod often needs to be tested and debugged to get right.

I have been doing some experimenting recently with a new Dimension Engineering controller - the Sabertooth 2x50 see -

http://www.dimensionengineering.com/Sabertooth2x50HV.htm

This looks quite interesting as it is a 50Amp 48V 2 channel unit with peaks up to 100Amp per channel so it should handle bigger platform loads. My hope is to add comms for it to the 40PSU-1 card but I've a bit of work to do on that yet.

Ian

[kermit]

Thank you Ian
For your quick reply, I will put your comments thru
Please note, we are using Bonfiglioli Vectron inverters and drive units,
Thankfully I will get it at costprice(yes I`m still a Dutchman)
and hoping it will get my platform started.
The only parameter I have to consider then ,
will be our house current wich is 220 volts 50Hz 16 Amp and our house sockets can handle up to 3200watts.
kind regards Kermit

[kermit]

Hi ,
I have done some major investigation about gearing and motor,

Decided to go with 3 dof using 24volt 900watt industrial dc motors linked with a gearbox (and prob an extra stage gearbox) with a ratio of I=35 and specialized electrics all regulated for a maxium of 18 amp per motor ,
I know I will have less power but no burn out I hope .

I will build the moving parts like the set up used by Roland (triangle mounted drive units) but with normal gearboxes instead of bungee cords.
And Ian`s interface and controllers.
I have given the actuators back to my work,and ordered several other parts.
I also purchase a new crosscoupling with spline for Heave movement,
Roland,please can you tell me what is the total movement height of your setup near the stabilization rod in the middle of your setup,
I need to cut the spine to height and mount a limitswitch.
This decision hopefully will end some sleepless nights over what to do, I know I will encounter other problems but hey, it`s a hobby:)
greetz

[Roland]

Hi Henk,

3369

Above drawing shows my setup. Each actuator can do 45cm of travel, so the spline on the stabilizing rod should also me able to follow this travel, and accomodate for the +/- 14 degrees pitch and roll angles.

Note that I needed the stabilizing rod as my platform is hanging in the V-belts. If you use more ridgid actuator construction, you may not need it.
Ian's plunger system actually combines the stabilizing feature with weight balance.

Curious what kind of weight balance you are going to use?

[kermit]

Hi Roland,
I will use a springloaded crosscoupling with spline, also the motors and gear unit will use guidence of the potmeters.
According to our electricians the motors will spike/lower the Amps but will be dampend/compesated by some device( don`t know how its called).
The torquearm from the gearbox itself will be fitted with a so called softstart coupling with a special shock absorption system(some type of rubber) .
Also the driveunits itself will have enough torque to overcome the weight difference,and because I will using the potmeters , the programme will know its position.
Further the weight difference will be overcome by the motors just asking more or less amp up to a certain parameter,
after wich the device will step in resulting in a flaw during flight.
Again thats my understanding on what our electricians told me.
greetz

[Roland]

Henk,

Just a note on the importance of weight balance:
A small weight unbalance in my platform already results in big deviations in drive power.

Below video shows some heave tests I did: the scope shows current consumption (top wave) and platform position (bottom wave)
first 3 tests show correctly weight balanced drive: 0.5Hz, 1Hz, 1.3Hz. As speed increases, the required current also increases, but going up and going down requires the same amount of current (1.3Hz results in 30A current peaks = 1kW peak power)
The last test shows what happens when I added 10kg extra weight (by putting a sandbag on my lap) The current unbalance going up / down is nearly 50%. If you have a current limit in your drive, it means that the upward acceleration will be much more limited than the downward acceleration.

http://www.simprojects.nl/images/Platform_power.wmv

Edit: for some reason the movie will not playback on my system after several downloads. If you have the same problem, pls let me know, I'll make it into a you-tube video

[wannabeaflyer]

Excellent Info as always Roland Just to say thanks on behalf of all of us that follow your work...Cheers

[kermit]

Hi Roland,
There is certainly food for thought.
Although there is a difference in the drive approach
Yours is driven by eleasticbands and therefore there is the need of gradual build of force to overcome the enertia
and stretch of the elasticbands, the forces then will collaps as the weight is catapulted in the other direction .
As for mine it will be a so called coldsteel drive were ,
there is nearly no stretch it the drive therefore will be a more constant force/wave in the drive systeem.
Therefore the electric consumption will be more constant factor but thats theoretical physics I think.
Your comments made me think about frequency inverters again.
greetz

[Roland]

Hi Roland,
Yours is driven by eleasticbands and therefore there is the need of gradual build of force to overcome the enertia
and stretch of the elasticbands, the forces then will collaps as the weight is catapulted in the other direction .


Well, not exactly: The coupling from motor to platform is done via V-belts. As far as I know, these have hardly any elasticity. So my drive coupling is actually quite rigid.
The bungee cords are used to create a fixed opposing force for weight-balancing. They are not part of the drive.

[kermit]

Hi,
Maybe I have to watch closer then,
I thought the elasticbands were a part of the drive unit, because they stretch with the movement.
Did you attach them on the platform itself ?
In that case it will only put pullingforce on the platform, or do you have to ajust the pulling force on each side according to the weightbalance ratio.
How do you calculate that force, as you can see this is a learning curve for me:)
greetz

[Roland]

Henk,

Have a look at the followowing pages:

http://www.simprojects.nl/diy_motion_platform_iii.htm
http://www.simprojects.nl/platform_drive_calculations_iii.htm

and the other pages on the #III platform, which include some video's.

For the actuator forces, Ian's V2.0 driver has a utility that graphically shows you the velocities, acceleration and required (mechanical) power based on platform weight and (un) balance. You can enter your platform weight distribution and let you play with various parameters. Note that this utility assumes a center post for weight balance, different from mine in which each actuator has a weight balance system.

(The utility can run in demo mode)

[kermit]

Hi Roland,
Please can you tell me if Ian board can drive motors with the following
frequentie-inverter specs 0-10 volt or 4-20 mA or 0-20 mA.
greetz

[Roland]

Henk,

As far as I know, Ian's driver board typically uses I2C to control the MD03 motor controllers. He has also build versions that work via RS232 for driving Sabertooth controllers and RS485 for direct driving a SCN5 actuator. So he does not output DC voltage or current signals. But please double check with Ian.

[IanH1960]

Hi Roland,
Please can you tell me if Ian board can drive motors with the following
frequentie-inverter specs 0-10 volt or 4-20 mA or 0-20 mA.
greetz

Hi Henk,

Roland has it right - the standard 40SPU-1 board only does I2C output for MD03's.

I have a dual chip prototype board that can do 0-5V analog output with high/low direction signals but it isn't proven. It also has possibilities for direct RS232 serial output at good bauds from the 2nd onbaord microcontroller chip.

Do you have a link to the manual/data sheet for the inverter you are interested in - I couldn't find it via google. Does it only accept commands in the formats you listed?

Ian

PS Roland - your full-size actuator on your web site is looking great!

[kermit]

Hi Ian,
Herewith the requested link
http://www.elstocontrols.nl/pdfdocs/BVE004-1.pdf
greetz

[Roland]

@ Henk: Looks like it really needs 0 ~ 10V (or 0 ~ 20 mA) for speed control, and a Forward/reverse logic signal for direction control, though the spec is not completely clear on the voltage level of this logic.

To be honest, these specs seem to be written for people who are familiar with these control units. There are a lot of items that are pretty confusing.

Is the forward/reverse fool-proof? what happens when you switch into reverse at full speed?

Anyway Ian's 0 ~ 5V prototype with direction signals should be pretty usefull; you could add a 250 Ohm resistor to make it into 0 ~ 20mA signal.

@ Ian: how do you generate the 0 ~ 5V? If it is coming from a CPU PWM output, it could be driven via an opto coupler to achieve the (often needed) isolation. That's how I plan to do my next generation D/A converter
(PS: Thanks ! Yes the full size #IV actuator came out pretty well. Torque and speed actually better than expected, also efficiency looks good. Two more units to build....)

[kermit]

Is the forward/reverse fool-proof? what happens when you switch into reverse at full speed?

Hi Roland this question I have already ask,

The motor decellerate (wich can be regulated to a point by the inverter) on his own magnetic force,and excellerate in the other direction.
Thus leave little out of sync but you are talking milliseconds at topspeeds ,
I think I have to worry about the forces working on the Cessna cockpit with these kind of sudden movements.
The platform itself has been calculated and constructed to take all the punishment I can throw at it and a little more.
The motors and gearboxunit has been calculated to take about 500 kg weightload pull at 30m/min each
(winch drumsize 200 mm)but will be tested for safety on our testrig.
These units where left over from a project and where lying in the warehouse for some time now, only to be picked up by me.
I will be asking about the logic voltage today although I don`t know why.
I`ll hope the prototype from Ian can be ajusted to the needs I have or rather the inverter
greetz Henk

[IanH1960]

Hi Henk,

Looking at the spec sheets I too am not familiar with much of the information. I'm not sure how the braking works.

It looks like direction is instructed by 12V signals on terminals 3 and 4, I'm afraid my card would not be able to manage the 12V levels - too high. There is no mention of what the actual voltage threshold is on those lines (it will be somewhere below 12V) at which they are considered logic high.

I might be able to provide 10V or 0-20mA speed demands - the card works the way Roland suggested with optocouplers which provide some scope for adjusting voltage and current levels. However this would take me a bit of time to work on.

If your platform is a 3DOF unit then the three inverters would need 9 outputs to control them (2 x direction & 1 x speed each inverter) - again the card wouldn't manage this as it doesn't have that many outputs.

I'm not sure if I can help with these inverters I'm afraid - the 12V levels and number of outputs required are a problem. Is your platform 2 or 3 DOF?

I'll have a look at the 10V speed demand output possibilities when I get a chance, but it'll probably be week or so before I can manage.

Ian

[kermit]

Hi Ian, I have build the platform in a way ,
I still can change the axis, the coupling has been bolted(6x M12) on a piece of metalplate.
So if needed it can be removed
also the motobrackets can be moved or removed to my likings.
Because I have no final PLC still looking :(
For now i would be happy to have 2 dof just to get me on the road , if your card can manage that.
thanks in advance
greetz

[kermit]

Hi,
Sadly,I have been let go , and had to change jobs.
But before that,
I managed to collect my ac motors/gearboxes and the needed inverters(synplus),
I have them mounted on my platform , but now I`m stuck.
want to use a Velleman K8055 interface card , I know that some people know how to connect them ,
I have tried to contact them but with no luck.

The velleman card wich connect to the Pc using usb does have PMW and DAC outputs(0-5 volts) en can use potentiometers for bank and roll inputs.

With the velleman testing software, I can see changing values when I rotate the disk on the potmeter.
Also I can see changing values when using Jimms page software, so the card is oke.

For now I dont know how to connect the velleman card to the inverters,
I have tried with pmw and dac outputs ,
but the inverters dont react to the inputs when using FSX with Jimms Page software.
Does anyone knows how to connect them
regards Henk

[Roland]

Hi Henk,

Sorry to hear about your situation. I really hope you'll find something new soon.

Regarding the AC motors and inverters, are these still the units from the link you showed earlier?
If so, I would start trying to get the motors spinning by applying DC voltage control signal to the inverters first: According the spec, they should be able to accept 0 - 10V speed control input.
Just use a battery and potmeter (or variable supply) and test this first. Then step by step add Velleman etc.

There probably need to be set some dip-switches or something to configure the inverters. If all fails, you need to find someone who knows these inverters.

I still prefer DC motors and standard H-bridges. Just now playing with Ian's 64SPU card.

Good luck, also with the job!

[kermit]

Hi Roland ,
I had to return the motors and gearboxes back ,
And buy others for now I have 0,5kw 3ph 230 v motors and 1 to 40 ratio gearboxes,
Luckily I already purchased the inverters, bonfi vectors with build in pid control
At my new job I started a course of industrial automation hoping to gather enough info to write programs /parameters, but for now i'm only a newbe.

I can give the inverters all sorts of commands by pressing switches on the display and start the motors
With Jimms software i can see data transferred from Fsx ,
Also when I rotate the disk on the potmeters
I can see values changing in Jimms software so I know the board working,
I think is a good idea to try Potmeter and a 10 volt source to experiment on the inverter just to see if it works ,
Regards Henk