Racing/Flight Simulator Motion Control
rough_wood
Posts: 61
I am looking to make a racing/flight simulator for under $5,000.· I am planning on using the Propeller to control the motion of the platform that rotates the driver to give the feel of G forces. The problem I am seeming to have is that to get the right response and range of motion it may not be feasable.
The moment of inertia is about 30Kgm^2. I want it to be able to accelerate at about 6.28m/s^2, and it needs to be able to rotate with an angular velocity of at least .5RPS. The motors will have to be able to take that rotating mass and quickly reverse direction and send it in the other way for example when going from throttle to brakes.
It needs to have 180 degrees of motion is pitch and roll, and 360 degrees in yaw for racing, and I'd like it to be able to have 360 in all directions for a racing simulator. I also intend to have a 4rth DOF which will be Heave.
What sorts of motion controllers will be powerful enough to put this mass in known orientations and is controllable by Propeller? I was looking at 2 stepper motors per axis but I've been told Steppers are mainly to position and hold, and not to constantly move something around. I have seen similar setups done with Windshield Wiper Motors, but they don't have quick enough response or enough range of motion. The platform and driver being moved will weigh under 400lb.
To do this with hydraulics would be difficult given the range of motion of rotation. My intuition tells me it needs to be done by electric motors of some kind.
It will need to know where it is, whether it be steppers or having normal motors with a 3Axis Accelerometer under the seat for example.
So again, the main thing is locating the proper motors and seeing if the price is feasable. Then I will have to set up the Propeller to control the motion. Anyone have suggestions for what motors to use and where to find them? I figured out I need about 200Nm per axis to accelerate the inertia at the desired alpha.
For a cheap example with less response and range of motion search youtube for "Thanos Simulator". Another similar one with proper response but not enough motion is "Force Dynamics 101".
Thanks
The moment of inertia is about 30Kgm^2. I want it to be able to accelerate at about 6.28m/s^2, and it needs to be able to rotate with an angular velocity of at least .5RPS. The motors will have to be able to take that rotating mass and quickly reverse direction and send it in the other way for example when going from throttle to brakes.
It needs to have 180 degrees of motion is pitch and roll, and 360 degrees in yaw for racing, and I'd like it to be able to have 360 in all directions for a racing simulator. I also intend to have a 4rth DOF which will be Heave.
What sorts of motion controllers will be powerful enough to put this mass in known orientations and is controllable by Propeller? I was looking at 2 stepper motors per axis but I've been told Steppers are mainly to position and hold, and not to constantly move something around. I have seen similar setups done with Windshield Wiper Motors, but they don't have quick enough response or enough range of motion. The platform and driver being moved will weigh under 400lb.
To do this with hydraulics would be difficult given the range of motion of rotation. My intuition tells me it needs to be done by electric motors of some kind.
It will need to know where it is, whether it be steppers or having normal motors with a 3Axis Accelerometer under the seat for example.
So again, the main thing is locating the proper motors and seeing if the price is feasable. Then I will have to set up the Propeller to control the motion. Anyone have suggestions for what motors to use and where to find them? I figured out I need about 200Nm per axis to accelerate the inertia at the desired alpha.
For a cheap example with less response and range of motion search youtube for "Thanos Simulator". Another similar one with proper response but not enough motion is "Force Dynamics 101".
Thanks
Comments
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Airspace V - international hangar flying!
www.airspace-v.com/ggadgets for tools & toys
Know a place where I can find them?
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Airspace V - international hangar flying!
www.airspace-v.com/ggadgets for tools & toys
http://www.edriveactuators.com/downloads.html
They don't list price. I'll have to get a quote probably Tuesday.
You have plenty of hydraulic motors out there. A hydraulic motor is like electric one (its shaft can rotate in each direction endlessly). You have much more power in smaller space. To control it you need a good proportional valve controlled by 4..20mA/+-10V... and of course some simulations (mathlab: math model of the system (piping, valve characteristics, pump characteristics, system weight, inertia, attrition...)) to find out the best parameters for closed loop regulator
I have made (in cast iron pipe industry) an application (with Siemens PLC) where a·casting machine (liquid iron 1500°C) of 12 tons·was controlled (speed/position on one axis only) by a prop valve (2000 lpm(liters per minute) capable of 150Hz operation from fully open in one direction to fully open in oposite direction) driving a 7 meter cylinder with a regenerative circuit. Hydraulic pressure 100bar. The machine has a run of 6.5 meters with accuracy/repeatibility of 0.2mm with acceleration/deceleration of 2.5m/s^2.
The movement·was·very stable also in acceleration / decelration (without pendulum of some kind), non easy thing seen the mass in movement. In the mathematical model it was fundamental to distinguish the part of rigid pipe from that of flexible one and the compression constant of the hydraulic oil even if minimal.
Leon
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle
Well, 400lb is about 180kg. So for an acceleration of 6.28m/s^2 plus gravity that is a force of
F=ma=180*(6.28+9.8)=2,900N <- about 650 lbs
Now, lets say that you want it to be able to move a distance of 0.5m. Then the maximum speed is
v=sqrt(2*a*s)=sqrt(2*6.28*0.5)=2.5m/s
Then we can figure the peak power you need to heave the thing.
P=F*v=2,900*2.5=7.25 kW
You can do similar calcs for the rotation except that you need a value for rotational acceleration (or was the 6.28 meant to be r/(s^2)? If it was then the power required for each axis will be around 650 W).
The only one that is difficult for hydraulics is your 360 degrees spin. Even that isn't really a problem because you simply have a motor geared down to drive it. However, the kind of hydraulics you need for this will probably run to $10,000+... The valves alone will probably cost $300+ each. So simply on cost grounds your probably better going electric.
To be able to tell where it is your best bet is to put an absolute encoder on each axis. You can often order your actuators with these.
stevenmess2004 covers it pretty thoroughly. Rather than trying to recreate the actual maneuvers of a plane, "real" flight simulators approximate the "feel" of being in a plane. For example, while taxiing, if you make a turn, the sim does not actually turn at all, it tilts to the opposite side as you are turning which tricks you into into thinking you are feeling inertia into the turn.
A professional flight simulator uses 6 hydraulic cylinders to create an environment so realistic that the U.S. FAA can certify you without you ever setting foot in the actual aircraft.
Here is a picture of such a simulator:
http://www.linuxjournal.com/files/linuxjournal.com/linuxjournal/articles/033/3368/3368f2.png
The 6 cylinder configuration shown can give the feeling of pitch, roll, yaw, buffet, acceleration, deceleration... the only thing it cannot do is a full roll... it'll try, though, by rolling up on to one side, then flipping around to meet itself on the other. Fun, but not exactly like the real thing
Given that you have around $5,000, and the pictured sim costs around $15 million (retail... includes mainframe to run the thing), I'm guessing you would rather have a close approximation... try pneumatics, they're a lot less messy, and you can get them through many car parts outlets.
You may also be interested in this thread: http://forums.parallax.com/foums/default.aspx?f=25&p=1&m=343952
You may want to skip ahead to page 5 or 6...
I'm going to be using that system as the foundation for a sim IO cabinet, among other things.
Ned
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
"They may have computers, and other weapons of mass destruction." - Janet Reno
dMajo:
I am considering hydraulics, the only issue is I assume they will be more expensive. Also I have never worked with Hydraulics at all, so I have no intuition for them. Can you set them to open and close slowly or at certain speeds? I assume the response would be quicker than an actuator due to the internal inertia whereas in Hydraulics I picture only having to operate small valves.
This thing doesn't have to be super accurate, I am not looking to sell this to an F1 team. It mainly just needs to respond quickly. Today I intend to get a 7-12V car wire to run my Accelerometer in my car to see how fast it's response is, to get a better feel. Obviously F1 cars will transition much faster.
Do you have recommended suppliers for the application i am desribing?
Leon:
Those are out of my price range, but thanks though.
Steven:
There will be translation for heave yes, but the 6.38 was rad/s^2. I am looking to create angular acceleration. My intertia in all 3 axis is about 30Kgm^2. I want the full motion because I think I can design it in, and rather than having a large amount of the motion I'd rather have all of it.
I'll look in to those encoders. Have a suggested supplier?
WNed:
If this will cover flight simulators I will want 360 degrees in all directions. I know commercial ones just barely move but when I fly flight simulators I fly fighters. I'd want it to be able to go upside down. Basically for flight sim I would direcly mimick the orientation of the aircraft and have a little heave to cover buffeting on high G or turbulence type stuff. For complete 360 I'd have to go with gear reduced motors.
I'm staying away from pneumatics since the fluid is compressable.
Everyone:
Do you know where I can find motors that are powerful enough and will have enough response to rotate this thing should I decide to aim for 360 degree motion? It's real hard googling up products with the right specs. If I choose to only cover racing I am currently looking at http://www.edriveactuators.com/downloads.html·but I'll also check out any suppliers for Hydraulics and such that you guys suggest.
Thanks for the help so far!
Wasn't this another progress they made for the Columbia 500 bizjet that they introduced electro-only no-hydraulics actuators for the simulator? BTW, at founding the CEO was an ex-MS-VP. He probably still is but I don't know.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Airspace V - international hangar flying!
www.airspace-v.com/ggadgets for tools & toys
I think that if you take a look at the Canadian D-Box Platform for home theaters, you will find that it is driven in three axes by high speed electric motors and, I believe, lead screws.
Regards,
TCIII
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
If you are going to send·a Robot·to save the world, you·better make sure it likes it the way it is!
Your proposing to move a large amount of stuff around with some fairly significant forces and accelerations. Make sure that whatever you build will stand up to the forces you generate. Also, make sure that your well strapped in. I don't want to hear that you've built your simulator and then the first time you roll your plane upside down you fall out and break your neck... Also if you use hydraulics be extra careful. If you get a small hole in a pipe the high pressure fluid escaping can do some real damage.
First off all there are some commercial platforms that do use electrics rather than hydraulics but their not very common yet. First of all we need to figure out exactly what you want. By 360 degrees I assume that you mean continuous rotation rather than just being able to start at 0 degrees and then only rotate 360 degrees. So, to do that you either need a continuous rotation actuator or a linear actuator that uses a crank system.
From the calcs I did above you will need about 650W (say 800W to be generous) to generate the accelerations you want. So, if we start with an electric motor that should be fairly easy to find. If you go to your local hobby shop they should have something in that kind of range. Then it's simply a matter of providing some gearing to get the the speed range you want. 0.5 rps is 30 rpm. A typical hobby brushless motor of that size will run somewhere between 5,000-10,000 RPM so you'll need a gear ratio of 167-333 to 1. I'd say to use a worm drive reduction however that has a major problem in this case. In a worm drive if the input drive stops, the output will lock up and can't rotate. This means if your motor fails or you make a mistake in your programming the drive system will try and stop everything instantly which will cause some very big forces.
You could maybe have a look at a 4wd or boat winch gearbox and motor. They have reasonably powerful motors and have decent reduction ratios. You'll have to figure out some way of attaching it though and will also need to build a speed controller for it (watch out for the currents required).
Another option is to look at the motors out of a direct drive washing machine. They are normally brushless and should have a reasonable speed range. However, you'll have to make your own speed controller again and it will probably still need gearing down to achieve a reasonable accuracy.
You could use pneumatics but that will be fairly expensive like hydraulics. You could maybe look at using the motors out of air tools but reversing them could be a problem.
You could use linear actuators in a crank arrangement but I personally think that that would be a big pain in the neck making everything strong enough. You'd also need at least two actuators on each axis to get a full 360 degrees.
this whole project is more in the realm of industrial controls and doesn't seem like a hobbyist project at all.
There are off the shelf servo systems (3 phase motor + absolute encoder, drive, controller) that would be super simple to implement, the mechanical engineering, fabrication, and assembly is the hard part.
I agree with your assertion that stepper motors don't fit the application.
The cheapest thing I can professionally recommend of off the top of my head is the Lexium Motion Controller and drive system from Telemecanique.
Thousands of dollars, doesn't involve the Propeller, though.
You should look at Automation Direct. They have many types of drive and control systems there. That and the documentation w/it that could give you a very good idea of what's available. If you were to buy from them it would probably be waay over five grand for your drive system, even though they are cheaper than others, but maybe not. Making your own controller will cut some of the cost. Hopefully you're fabricating the structure too because I would guess that that will take up an incredibly larger amount of funding than anything else.
If there is a fair or carnival around you should look at some of the rides that rotate around multiple axis. They use some pretty burly direct drive systems - and make some people puke too!
no time this week to post more things. Anyway this can't be a cheep project but also not a 15 milion one.
But as you can see prof sims use hydraulics BECAUSE IT IS CHEAPER. When you have to suddently move something (big mass) you need big energy. Because you need smooth movement you need proportional valves (fully closed to fully opened means that also all the way between is available: they are infact open in proportion to the signal that drive them). Hydraulics have the advantage (ffor example this application) that you can use accumulators. In this way you can underdimension the pump system and save money. If you are smothly/slowly moving you small quantity of oil. If you have a strong but short movement your ccylinder take the missing oil from the accumulators and during waiting and/or low speed (low oil draining) movement they will be recharged again by the pump system.
Pneumatics won't work: you need a media that can not be compressed otherwise you will introduce lags in response.
Doing that by electric motors: it is possible, you will probably choose a DC ones due to a higer torque compared to AC. To obtain strong immediate movement, but also smooth when needed you will need high power motors and high power (pwm) speed controlers. All this will be more expensive than hydraulic solution.
regards
http://www.battlekits.com/robot_motors.htm
The PLC companies aren't in this business. It may be possible do make a simulator using a Control Logix or a high end Siemens. That would cost MUCH more than $5000 and they don't have the inverse kinematics code done.
I hate to put a damper on things but this thread needed a reality check.
This is a very ambitious project financially and technically.
It will have to use electric motors whits wold be powered with brushes.
Has anyone spotted a good source for the communication protocols for the various G force simulations? With a good protocol listing, MIDI was a piece of cake. I'd expect this will be a little more challenging.
Thanks.
Kevin, thanks for this link. I know it has been years since you posted it but for a simple (relatively) racing simulator with maybe just 3 DOF the motors and gearboxes from this site are perfect and much less expensive than hydraulics. I'd still like to roll my own controller using the prop and I think a 3 DOF controller is possible especially when we are only dealing with a game simulator and not some industrial control. This would still keep the application in a hobby type budget (certainly less than all my pipe organ stuff).
This site offers a wealth of information for anyone interested in a racing simulator and again, I think there are prop opportunities here. http://www.xsimulator.net/community/forums/diy-motion-simulator-building-q-a-faq.31/
Then you can play awesome tricks.
The six-legged Singer-Link platforms are amazing toys.
Forward acceleration, for instance, can be done with a very slight forward shove and a tilt UP to make it feel a hard shove.
Yaw and roll the same way. A hard initial surge to get the inner ear involved, but only a few degrees of actual rotation.
Look around for details on flight simulator platforms.
Even the early Link trainers did a good job of fooling the pilot into believing the motion was real.
A little thread drift here but as there is not much interest that should be no problem.
Your comment on Link trainers brings me almost full circle in my hobbies. I started with player pianos, pipe organs, Virtual Pipe organs, Racing Simulators. The original Link trainers used player piano rolls, and larger pneumatic actuators for the simulated commands. Vestal Press (don't know if they are still in business) from just outside of Binghamton NY carried many books which crossed over between player pianos and the Link trainers. If I recall correctly Edward Link was from that same area of Binghamton NY.
Today, many of the flight simulators are using the same technology as the racing simulators but with more degrees of freedom as a racing simulator really does not need to simulate a roll (well one strives not to need that axis as we are not strapped into the seat)
3 DOF is quite sufficient for my use and most in the racing sim community.
I was just hoping to pique interest in using the Prop for something it could, IMO, easily handle. More Prop sales equals more years before the dreaded EOL for this Micro. There are quite a few systems being built around the Are-Dweeb-No so I am sure the Prop would fit in very well.
Regarding the comments about the relative high cost of servo/proportional hydraulic valves, I recently had an opportunity to test a theory that I have had for a while. I took a hydraulic actuator with a quadrature encoder feedback but instead of a servo/proportional valve, I used a simple, low cost ($150) directional valve with a 24v DC solenoid coil. Using a simple H-bridge amplifier (Ebay $10) to drive this solenoid, I "closed the loop" using PID and found I was able to repeat to within a single quadrature count. This is an actual piece of industrial machinery and the performance is the same as a later model that features a $3,000 servo valve/integrated amplifier.
Since 1993, I don't know how many Vickers Proportional Valves I have purchased (I paid $1,800 because of volume) but we're talking four figures in terms of units....:frown:
If I understand this solution, you do not achieve much control over velocity is that correct?
Oh absolutely! Trapezoidal motion profiling, in fact; acceleration/deceleration=quad-counts/sec/sec, slew=quad-counts/sec
The only issue I have is the valve's dead-band due to spool overlap but compensating for this is quite straightforward.
Still think this is a good application for the Prop but given the limited response it would seem I am alone.
Sort of like the prop is fantastic for MIDI stuff but not too many applications have been implemented. A few to be sure but minuscule given the size of the MIDI controlled music world.
Not at all...the thing that attracted me to the Prop was its potential as a closed-loop motion controller. The frustrating thing is that stepper motors is about as far as this community goes when it comes to motion control. Even there, I haven't seen any true trapezoidal or S-curve velocity profiling.
For me though, I need several quadrature encoders running in the MHZ range but the Prop's counters don't handle quadrature so I am looking at external devices for this. Apart from that, the chip is ideal for this and other multi-axis closed-loop motion control applications.
We are currently playing with a design for our own integrated hydraulic actuators that incorporate a servo-motor, gear-pump, cylinder, etc. This eliminates the need for an external pump, reservoir, piping, chiller, etc. There is a gear-pump made be Settima in Italy which is amazingly quiet and very reasonably priced. Perfect for a flight simulator!!!
I hear you on steppers being the majority of interest and it is understandable.
I love PID loops (I have not seen a doctor about this) and used them extensively prior to my retirement. When they are set up right only an engineer could appreciate how well they work.
I would say, I'd have to brush up on the S-curve velocity profiling as IIRC I only had to do that a couple of times and I had a lot more hair then.
When you say Quadrature in the MHZ range how many MHZ are we discussing? I tend to write 90% of my code in PASM which screams and the balance in SPIN just to get things running and so far I have not hit any speed barriers but certainly HS quadrature would be an issue.
I'll check out that Settima gear pump. Thanks!
Not that this really counts, but I've did some variable acceleration experiments. The code was actually written for a hydraulic value but I used a continuous rotation servo in an attempt to illustrate the motion profile.
I included a constant acceleration feature to my servo contraption in an attempt to keep the motion smooth. Neither of these experiments were really closed loop (I don't think hobby servos count) so they're not really good examples. I do close the loop with some of my robots which use quadrature encoder feedback. I'm not at all pleased with my present level of motor control but I'm very interested in this sort of stuff.
BTW, I purchased a used pedal board and wired up to act as a MIDI controller. It's not much of an organ but the pedal board with two MIDI keyboards is a lot of fun.
Thanks for the links Duane! I'll see what I can digest from those. Obviously position accuracy is not ultra critical for a racing motion simulator but velocity might actually be more important.
I have one prop scanning 2 keyboards and a pedal board from a 1928 Wurlitzer Theater Organ using analog inputs (only 3 required) to implement 2nd touch for both KBs and pedals.
That prop also scans my stop tabs and a few switches (96) it sends out MIDI to my pipe chamber and to a PC running Hauptwerk & MidiTzer (if you have not used these they can be free and make a very convincing pipe organ. The entire pipe chamber is controlled by a 2nd Prop controlling over 1100 pipes.