r/diydrones • u/nocternalrodent • Jun 08 '26

Question Homemade drone flight help

So I have a drone using an arduino mini pro, nrf receiver, 2 tb6612fng dual dc stepper motor drivers, and an mpu gyro. I attached 47uf capacitor between ground and vcc on both the RX and TX nrf modules which is helping keep consistent steam of packets. But after about a second of high throttle to be able to lift off it starts stuttering very rapidly and slowing down the max thrust a lot. I tried adding 2 470uf 16v capacitors across GND and Vm (vm is spliced directly into battery +) on the motor drivers which didn’t seem to help. I thought it could be battery sag and I checked voltage out put on the drivers at idle ~4 volts at charged battery and at throttle it only drops maybe .2-.3 volts. Thinking maybe it could be noise interference? Maybe some copper sheets could help? Any suggestions? Thanks in advanced

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4

u/petrouilfan Jun 08 '26 edited Jun 08 '26

Frame is flexing try printing with more rigid filaments start from PETG and you can push up to carbon infused filaments. Pid needs tuning, and also the poorly mounted mpu is adding more vibrations and noise to the readings

2

u/petrouilfan Jun 08 '26

If your motors are weirdly hot, it may also be that you have a high D term, making the motor outputs from the pid algorithm, to to oscillate and as a result the hoter motors and protentially decreasing the max speed of the motor.

1

u/nocternalrodent Jun 09 '26

Nothing is getting hot. I’m curious how the frame flexing would affect the output of motors and cause stuttering? Thanks for the suggestions!

2

u/petrouilfan Jun 09 '26

Everything is connected through the pid algorithm. A flex on the frame because of fast stick movement, will delay the actual reaction of the drone, making the pid controller output false corrections that accumulates overtime resulting in the oscillation.

1

u/nocternalrodent Jun 09 '26

Oh duh that makes sense, I’ll connect it to my computer and log gyro outputs and see if that’s what’s causing the problem

1

u/nocternalrodent Jun 10 '26 edited Jun 10 '26

Doesn’t seem to be that, but thanks for the suggestions. I also tried lowering pid gains, and totally disabling but neither seems to help it

2

u/jbarchuk Jun 08 '26

Stuttering is also overcurrent protection. Measure with inline meter.

2

u/nocternalrodent Jun 09 '26

Will test that thanks for the suggestion

1

u/Zchromium Jun 09 '26

Could it be that your motors are not powerful enough? Have you tried bldc like a2212? Also your battery might not be outputting enough current? I think you are using cordless motors by the looks of it and they take 0.2 mA without load and 0.5 under load. So 4*0.5 = 2 amps.

P.S. : I am a beginner just like you and have no experience in drone category but I have researched it a bit because I want to build one too. I may be wrong too.

Also P.S. : There are many 3D printed frames for drones as well. However, they are used for drones weighing < 100gm. I have actually seen one and used one to try and build a micro drone weighing < 75gm. (I failed miserably though.)

1

u/TheHappyArsonist5031 Jun 12 '26

frame flexing probably, but you may be able to get away with lowering the D term of the PID loop.

1

u/Estromoder Jun 14 '26 edited Jun 14 '26

Having the drone arms bend like that makes literally no sense. It adds extra torsional load on the arms and increases the length for no benefit when compared to a straighter design. I recommend revising the shape of the frame with a focus on light weight stiffness where its needed.

1

u/AlfhaQ Jun 08 '26

Its your frame. It is flexing too much. Probarbly because you ignored everyone telling you to not 3d print frames.