DIY flight controller issues

[tharri29]

Hey,
Thanks in advance.

so I'm building a flight controller with a arduino mega and its coming along nicely but i have run into a wall and wonder is someone could lend a hand as i've research for days on in and nothing has fixed my issue

First off the Build

Frame : S500 PCB quadcopter kit W = 416 grams
Motor : 4x 920Kv 2212 brushless W = 60 grams x 4 = 240 grams
ESC : 4x 30A simonk peak = 40A W = 20 grams x 4 = 80 grams
BEC: 5v/3A
Propeller: 10 x 4.5
Battery: 2700mah 3s LiPo 11.1V 25C with 50C burst W = 196 grams
arduino mega: W 37grams
Total Flight weight: 969

issues and what i know

i know my props are positioned right and ive calibrated each esc manually.
but for some reason i can get off the ground not even at full throttle. it usually just flips over. also using the multiwii gui it seem to be a big power sag on the motors front right and back left. this indicates it seem to be a yaw drift but after a couple second the power drops so low the quad almost stop those motors all together. i assume this is just because its not flying but this could be a issue.last but not least when i have the quad on the test stand and crank the throttle all the way up it seems to make the motor power jump uncontrollably. could anyone shine some light on the problem and/or tell me if i have enough power to fly what i have on it

Thanks,

[Kbev5709]

You make no mention of what ACC/gyro you are using. The flipping could be an issue with the orientation of the sensor, providing you have one.

The usual cause of flipping upon trying to take off is wrong motor rotation, or, wrong ESC wire on wrong pin, or, props on wrong, either upside down or wrong rotation, or even just a really horribly balanced quad. Those 920Kv motors and 10x4.5 props are more than enough to lift the weight.

Is your battery balanced (cell to cell, not position on the quad) and fully charged when testing?

Of course, trying to fly with no ACC and gyro will have the same effect. Forgive me if I should just assume you know you need an ACC and Gyro. At least a gyro.

[wastevenson]

You probably have issues with your gyro / acc orientation.

Ensure your axis orientation is set properly for your sensors or your gyro will be conflicting with your acc.

You want your gyro and acc to match so when you pitch or roll, everything is on the same page.

[tharri29]

Thanks Wastevenson ,

im using a mpu6050 and it seems to be working. i checked the orientation against what multiwii said it should do when roll, pitch, and yawing. it seems spot on. i usually wait til the battery is fully charged then try to see if it will fly.

thanks

[Kbev5709]

OK, so you know it isn't gyro related. If you still have the issues check the other stuff I said.

The usual cause of flipping upon trying to take off is wrong motor rotation, or, wrong ESC wire on wrong pin, or, props on wrong, either upside down or wrong rotation, or even just a really horribly balanced quad.

[tharri29]

question Kbev,

while im still trying to figure out whats going wrong. what would cause one motor to be at 1300 while the other three motor are at 1900 in the gui. it always seem that one or two motor are sagging compared to the others

[Kbev5709]

question Kbev,
while im still trying to figure out whats going wrong. what would cause one motor to be at 1300 while the other three motor are at 1900 in the gui. it always seem that one or two motor are sagging compared to the others

Does it never go past 1300 and always the same motor? If it is an improperly calibrated ESC it would tend to do that.

If it goes to 1900 then slows down to 1300? If you are testing in the GUI with props off and one or more motors slows down and even stops, it is normal and caused by a lack of motion input to the sensors. Since you mention that one or two motors sag compared to the others, I would assume it is the second question and answer. It is perfectly normal.

If you have not resolved your spinning issue you might check your config.h to see in the PID controller section if your code looks like this

Code: Select all

 /* NEW: not used anymore for servo coptertypes  <== NEEDS FIXING - MOVE TO WIKI */
    #define YAW_DIRECTION 1
    //#define YAW_DIRECTION -1 // if you want to reverse the yaw correction direction

If you have crazy yaw issues that you can't stop, try changing the statement there. If it already looks like the -1 is defined, there's your problem. If not defined, try it that way.

If you have resolved your other issues it would be time to give it a careful flight test.

[wastevenson]

im using a mpu6050 and it seems to be working. i checked the orientation against what multiwii said it should do when roll, pitch, and yawing.

Thought it was worth a shot.

The only times I have had my copter flip on take-off like you described, was having the motors (ESC) on the wrong pin on my Mega, and another time, when I had to force orientation for my 6050. My acc's X, was my gyro's -Y. Or something like that. So while the visuals would show proper pitch and roll, the board was showing different data for the accelerometer so it would over-correct because it was getting feedback opposite to what it was expecting / needing to stay level.

[wastevenson]

Did you get this sorted out for yourself?