2DOF Down Under sim.

I have been planning and building a 2DOF sim for a while now. I am useing electric motors and chain drive reductions.

What I would like to know is how fast a motion speed should I try to achieve. Like how many degrees or radians per second of pitch or roll ?

If other builders are interested this is a low cost sim as most parts have come from the rubish tip so far.
The motors are old vehicle generators ( like from old series II Landrovers or VW beetles). A small wiring change to bring out the field windings and you have a 400W ( @ 12V DC) 1000RPM motor.
The chains and sprockets are old bicycle stuff.
The motor drives are from Oatley electronics here in AU and have an analogue input. $39 Au or about 25EUR. http://secure.oatleyelectronics.com//pr ... 9a82d9dbac

I am curently desigining the circuits/PCB of the closed loop position feedback (just a bunch of op amps) that will be connected between the veleman 8055 analog output and the motor drives.

When I get it fully operational I will post some pictures and diagrams.

Zap.

Gidday, now that is an idea I havent thought of!
I am a automotive engineer and have been racking my brains on finding a motor that has more power than a wiper motor and I never thought of the old humble generator.
Well done, please tell me more about your field winding mod.

Generator to motor modifications

Most generators have two terminals on the casing, one is useually labled F for field and this is the wired to the regulator. This normally varies the field voltage to adjust the output voltage/charge current. This F terminal is one wire of the field windings. The other wire of the field winding is useually earthed to the casing.

The second terminal is the B terminal and this goes to the battery useually via a blocking diode. This terminal is wired to one of the rotor brushes , the other rotor brush wire goes to the earthed casing as well.

It is these two earthed casing wires that need to be disconected and brought out of the geny/motor, Most I have modified just required the earted wires to be desoldered from a rivited brass terminal and then joined to new wire and heat shrink insulated to extend them to the outside.

You should then have 4 wires to the motor, two new ones and two existing terminals. The motor will run if you covvect power to the field winding and the rotor brushes, There is one trick still and that is the motor will always spin the same way even if you reverse the power wires. The reason being is you have reversed the magnetic fields in both the rotor and the field windings.
To fix this and make a reversing motor you place a bridge rectifier between your power wires and the field winding so the magnetic field in the fields stay the same no matter witch way you apply power the motor.

If needed I'll take some photos and maybe a circuit drawing drawing .

Also, 12v generators are designed to put out a lot more than 12v and conversly the run quite happily on 24v as motors with up to 1kw of output but you have to make sure you leave the little air fan pully on it to keep it cool.

Zap

Hi Zap,

Yes please do take some photos and post a wiring schematic. I, like CW, have been on the constant lookout for suitable motors to drive actuators. Unfortunately NZ is a small country and lacks an abundance of resources to draw from. :?
I'm assuming if I ran 24v into one of those old fashioned generators I could double the rpm to 2000?
1000watts of power! yes please! :razz:
hmm now where am I going to find a 42Ax3 power supply. :

Evanf

Here is the diagram, I hope this insertion works. If it does I'll put some photos of the motors in tonight.



Zap.

Hi Zap the server this forum is hosted on isn't windows naming convention friendly. You'll have to close up the filename, underscores _ are allowed but no gaps.

Hi Zap,
interesting.
Notice the Kiwis come out of the woodwork when someone says cheap! Thanks for the diagram, it is a good method of direction reversal.
Do you have any ideas on speed reduction.

Cheers

CW

Mechanical speed reductions, well you could say I've used everthing so far and it depends on $ and reliability you want.

My four 3.5 m x 4m roller doors on my shed use old International Truck windscreen wiper motors that have an internal double reduction and brass gears.

Some of my automated yard gates use automotive steering boxes. (most are quarter to half turn units, some are rack and pinion type. ( NB: EvanF this might be OK for heavy linear drives )

Others use trailer jocky wheel steel lead screw, most jocky wheels have a good course square thread , some are cheap triangle threaded rod ( wears out quick). ( EvanF: another linear drive method)

Some very old tractor steering boxes have full circle worm drives.

My 6m satellite dish drives are old conveyor gearboxes that have been thrown out because of stripped teeth. most can be repaired with judisious use of the arc welder / mig and the angle grinder because you never need the strength they were made for in the first place.

Some other electric linear actuators i've made for adjusting agricultural implements used a walking chain method.( I'll have to attach some photos tonight) ( Another linear drive fou you EvanF )

Belts and pulleys , well I can only say that I only use them when I really have to. The reason is I have to buy the belts , I get the pulleys from the local scrap merchant at scrap aluminum prices.

Reduction gear boxes ( gear heads), yes I get them ocasionally from the scrap dealer again, and as useual the AC electric motor is burnt out, The problem is there is never a matching pair , well I suppose beggars can't be choosers.

Any way I'll try to get some photos up on this board tonight or tomorow.

Zap.

What a goldmine of ideas. Never thought of a jockey wheel thread. Hmmm I guess an old fashioned window windup mechanism found in old houses might have a decent thread too.

Here are some pictures.

These two are modified Lucas generators , note that one brush mount is normally bolted to the earth casing in these models so I just used plastic bolts instead. These motors are spares from an old scrapped project.



The folowing electric linear actuator (12v ram) is a trailer jocky wheel with the handle removed a thrust bearing added then a sprocket. The motor is a stuffed bilge pump. This ram lifts a push blade on the four wheeler (not mounted in photo ) it is powerfull enough to lift the bike front clean off the ground.



This next electric ram is a walking chain type, the duplex chain is fixed to each end of the moving part. The trick here is the chain rests on the moving part where it passes the drive sprocket (slot in outer box section ). This one is geared down greatly and takes 30 seconds from end to end. The motor is a model plane starter. This 'ram' is also used on the front of a box trailer for tipping it to empty it. It will easily lift 500kg.



This next pic is a cut down rack and pinion steering box from a past project. Add a motor and a couple of pullys and its an electric 'ram' or what ever else you want to move fast.



Also here is a couple of rather large screww jacks that I picked up for nothing. They have 1kw three phase motors coupled to a worm drive reduction with optical encoders and then to worm drive screw jacks that are about 2m long and 50mm in dia.



I don't know what i'll use them for ( full sized A380 sim ha ha ) but its amazing what can be had if you keep your eyes out.


Zap.

Hi zaphod42,

Just found your postings and thought I'd give you the 'Cheaper Inventors Award' for innovation.

Great to see some (reliable) lower-tech ideas used for some high-tech solutions.

Nice work mate...