best layout for motors?

Hi all,

I am building my own DIY motion rig, which is coming out quite nicely if I may add, but now that I have to attach the motors, I have come to a doubt: for a 2DOF system, roll and pitch, is it best to put two motors symmetrical at the back of the moving seat or is it best to put one in the center back for pitch and one in the center side for roll?

Thanks,

Paolo.

Thank you for your reply, I am choosing 2DOF full frame, upgradeable to 3DOF or even 4 DOF (even though I do not really think 4 is necessary for car simulations). My idea would be to put the motors in the back so that for pitch they would both concur to motion, whereas with central motors only one would be involved, so double fatigue and half result.
However, I have no idea which lever length are most used. I was thinking between 50 and 100mm... Does it make sense?

Thanks!

Hi again,

unfortunately my trip to the scrapeyard allowed me to find only two different motors, which rev at different speeds, so I might be forced to choose a layout where the two motors do independent things... Or is there a way to synchronize different motors so that they can work together doing the same thing, like pitch, for ecample?... ah, confusion is queen in my mind...

Exactly... Is this the reason why usually long arms are used to reach the back of the seat? But that alone is not a long leverage...

Yup... done. One of the motors had a diode inside preventing it from working in reverse... removed.

Update: quite disappointed. I have set up all system, everything working all right until I add some weight - pedals and wheel. After this, motors aren't able to move the system reliably. One of the two, especially, cannot pull the seat (it can push it all right though), and after a while the motor driver shuts off perhaps due to overheating, even if it feels not that hot to the touch. Too bad, I really thought those two motors were big enough to be able to move the whole system. Might there be anything I overlooked?

of course, here they are:


Self-made U-joint:


First motor:


Second motor:

UPDATE of the update: apparently there is a better wiring option for my first motor. When removing the shell connection, I used the remaining two wires, which gave the highest speed but apparently not the highest torque. I then decided to extract the third pole of the motor and I test it, thus obtaining lower speed but seemingly higher force. Now it seems to behave better. Will try the same trick with the other motor as well. I'll keep you updated.

Yep, I have done that, according to the physical limits set by my steel frame... But now, after playing around with motor pins, the situation has much improved, even if from time to time one of the two drivers still shuts down after a while... I still have to find out why...

Update: well, everything seems to be fine, at least from the general point of view... I still have a couple of issues:

1- PWM causes huge current spikes which tend to disturb USB; I think a very good quality cable is needed;
2- from time to time, one of the two motors becomes inactive; it looks like an overcurrent problem, I think one of the h-bridge chips enters some protection mode and therefore needs reset. I have to investigate further.

I have moved the rest of the question to a more relevant section of the forum.

Thanks again!