Budget Compact 6DOF Universal VR Flight / Racing rig - MSFS, SMC3, FlyPT, Transducers, Controls

Yes, the PC PSU maybe detect a fluctuation and it go to protection mode. Keep in mind this: At maximum (I mean when you want the motors follow a square signal) each motor provides 250W but considering a efficiency of 75% (as example) it consumes around 333W. All 6 motors will consumes arount 2kW ant that amount of power is provided by the PSUs. Takin into account the PSUs have an efficiency of 90% they consumes around 2200W. Well, in your country the output voltage is 120V so the current to provide the 2200W will be 18,3 amps (considering the power factor is 1 but it will be less and the current surely can raise to 20 amps). It match if the motors are fully loaded but even without they aren't running at full load a square signal is a shock for the inductances and the circuitery, maybe the curent is not 20A but not much less. That amount of current causes a voltage drop that your PC PSU detect and enter in protection mode. It maybe can cause motor PSU failure or breakdown be care of that.

As attyla says (he is a good adviser) test with square signal is not the best way to test the rig, use a sine wave or a triangular wave to test hard changes if you want but avoid sqre signals.

Ok, then there must be some voltage droop on the power line. This would also explain why the motor supplies keep working while some other faults out. Can you monitor the voltage? If you don't have a fast reacting meter a good-old light bulb should also show fluctuations because they are quite sensitive to voltage changes.

Ouch. Yes, that makes sense. Considering most US/Canada circuits are rigged for 15A loads (circuit breakers are triggered if it's over 15A I think) I must be getting really close to that! So, I guess I stress-tested my PSU/diver/motor combos LOL!

When a random board glitches - only one of two motor arms stops, that's the "disable" function kicking in but only for that motor - the other motor and other boards keep working fine. I know it's the disable function because I programmed a pin to go low when it's triggered so it triggers the relay that cuts power to all motors . I can see the relay light blink out when it happens for one of the 3 relays. How the disable function kicks in is puzzling because the range is not exceeded. But Maybe it's because there is a power dip something happens with the 5V voltage that's fed into the sensor so it drops below the cutoff for a moment even without the arm moving as much.

OK I will test with side or a triangle way, and then will try with a top platform so I can verify that everything is moving correctly. I'm using real-size 3D-printed mock-up motor arms. I should be able to cut the metal arms next week but I decided to test everything before I do with a mock-up, and it was a good idea - I had to redesign the magnet holder attachments because they were coming loose. The plastic arms should be strong enough to hold an empty platform without the seat etc. and test gentle movements as a proof of concept.

My UPS (Uninterruptable Power Supply) for my PC did the same thing a lightbulb would - it clearly went into battery protection mode each time this glitch happened, so that confirms the voltage droop. The UPS software is very basic, so I can't see the graphs etc. It was on another power outlet, so the drop was over the entire 15A circuit. I don't have a fast meter, but I think the UPS pretty much confirms the voltage droop.

"Square wave" means full speed forward, instant direction reversal and then full speed backward? This indeed causes a heavy current spike during reversal. A bit better would be a trapezoidal waveform that ramps down speed before direction change and then ramps up speed again with full speed plateaus between the ramps.
Sinus wave runs much smoother, of course. But it's not ideal for testing motor tuning. Overshoot and oscillations are only triggered by abrupt speed changes so the trapezoidal waveform is a better stress test.

Here's the test with the sine wave. The good news is that nothing failed at the rig, no DisableMotor function tripping, it was all working full-time. When I increased the range to the max (redlining in FlyPT Mover) it was still working, but I got the PC's UPS tripping again by the manual rapid heave movement all the way and back very fast (similar to square wave only more extreme). But the rig kept working after that.

I then plugged all the rig's PSUs into another outlet at the same room's opposite wall. UPS stopped tripping, but I could see the lights slightly dim not only at the same room, but at the entire house! Or at least what I could see from here (hallway, living room).

I kept the sinewave running at full range for a few minutes - all the parts remained cool - motors, drivers, rectifiers. Nothing tripped. I did notice the little blue display's voltmeters going up to 30V when changing directions. Those are not fast voltmeters so it's difficult to see what's going on. But the fact that it would register up to 30V is a bit concerning. Meaning there is some reverse current I guess. But so far, no driver has burned or even heated up. PSUs aren't tripping and rectifiers are cold. The big test will be under load and in real-life usage, once everything is working properly...

Wow, if the lights in the house dim during the no-load test I guess you get in trouble when the motors are loaded with the full weight of the rig. Can you measure the current draw of the PSUs at the mains input?

(BTW, that's why I will equip my rig with a three-phase 230V input. But that's a different story... It's a two-seater so way heavier and has 6 1kW motors)

If you test with the full load I still recommend doing the test with the batteries and LEDs I have suggested here. Or at least increase the speed and stroke VERY carefully while monitoring the voltage.

No I can't. I'll make sure to go very slowly. I could also reduce PWM from 255 to a lower number if there is enough force to move the rig. However 250W is on a weaker side, so I'd guess I need all the power those motors can deliver. I checked and most circuits in my house have 15A fuses, including both that go to my home office, where the rig is. One has the computer with its UPS, and the other I guess is shared with the hallways and the living room, which is why I saw those lights slightly dim. It didn't trip the breakers though. Overall my house is not old, built in the late 90's so the power distribution is very adequate.

I'll have to go very slowly with this... Also wouldn't want to fry the drivers or PSUs. Though again, so far I could sense no heat at all in any of the elements after a couple of minutes of constant motion.

I've completed and wired up the power/emergency stop/switchbox and assembler the top platform for testing the geometry and motion. So far so good. I think I need to move motors closer together because the platform ended up too low. My original calculation was for closer distance but I was trying to get them as wide as I can to maximize motion. The result may not have enough clearance for the pedals to pitch forward, and also the motor arm angles are not 90 degrees. Otherwise it seems to be moving right!

with the motors closer together you need less power to lift becauce of less angle from youre pushrods

More progress.
Power / Emergency Stop / Button box:



Seat, spine and pedal shelf assembly:

Hi, a question, are you sure the wood will be strong enough to bear a huge positive heave movement? be careful with that

No, I'm not sure, but I intend to limit the heave range to a more reasonable amount anyway, so it won't limit the roll/pitch/yaw too much. At the extremes, there isn't any room for other DOFs.

Some (careful) testing of the seat, spine and pedal assembly on plastic motor arms. Eventually one of the arms snapped at some later point, but I got the data I needed so I could proceed with other work until I could fabricate the metal motor arms, which was pushed to next week unfortunately. The pedal shelf can hit the front motor arms in some positions, so I will flip the top platform brackets to get a few more cm of height. I also now have measured my maximum top position, so I can install the gas strut, or both struts. I think I'll start with one, placed at the center, then see if I want both.

Well done! Although it's an important feature for a motion rig an emergency stop button looks somehow disturbing in an aircraft. An ejection seat handle would be more apropriate.

An ejection handle in, say, Boeing 737, would look equally disturbing Actually, the lack of an Emergency Stop button may serve as an ejection handle, as 1500W of power would eject the pilot during a violent maneuver or a rig crash That's why I got harness too.

Top platform assembled and attached:


Building left and right panel racks. The left side has the HOTAS and will have a 3D-printed buttonbox, and the right side has the On/Off + Emergency Stop + button box combo, and my 3D printed custom Throttle Quadrant from the 2DOF rig, along with 2 other modules.


Assembling Gear Button Box and MCP/GPS box (work in progress)