Kevin's Bi-Copter Thread

[jstremmler]

I am using an Omnibus F4 pro corner.

Channel map of my RX (S-BUS Optima D from Hitec) is AETR.

So pitch control is on Ch2. And if I do pitch forward Betaflight firmware shows 2000 pulses and if I do pitch backward the firmware shows 1000 pulses.

When I move the pitch stick forward, servo1 moves from neutral position backwards and servo2 moves from neutral position forward.
And now surprise surprise…

If I move the pitch stick backward servo1 also moves from neutral position backwards and servo2 from neutral position forward.
So whatever I do on the stick both servos move different ways and use only 50% of their way in on direction from neutral.

[jihlein]

# servo mix
smix 0 2 2 100 0 0 100 0
smix 1 2 1 -100 0 0 100 0
smix 2 3 2 100 0 0 100 0
smix 3 3 1 100 0 0 100 0

With an F4 controller using the built in BiCopter mixer, these servo mix cli commands are not necessary. I didn’t look at them carefully, but I suspect you are seeing the result of these servo mixes being applied on top of the standard BiCopter mix.

[jstremmler]

@jihlein: no, I get the same result when I key in the CLI: “smix reset, save” and then of course all smix commands are removed from the CLI. my smix commands are ok, have a look at: src/main/flight/servos.c
#if defined(USE_UNCOMMON_MIXERS)
static const servoMixer_t servoMixerBI[] = {
{ SERVO_BICOPTER_LEFT, INPUT_STABILIZED_YAW, 100, 0, 0, 100, 0 },
{ SERVO_BICOPTER_LEFT, INPUT_STABILIZED_PITCH, -100, 0, 0, 100, 0 },
{ SERVO_BICOPTER_RIGHT, INPUT_STABILIZED_YAW, 100, 0, 0, 100, 0 },
{ SERVO_BICOPTER_RIGHT, INPUT_STABILIZED_PITCH, 100, 0, 0, 100, 0 },
};
And you may believe it or not when I specify mixer to customairplane and set the motor mixer correctly then no servo moves.. but motors work of course…

[Kevin_Erik]

Woot I can fly backwards now!

Added Plasma-Tree Log.

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[jihlein]

What little I know of BetaFlight tells me that with the OmniBus F4 Pro corner and F4 chip with the large flash size ( flash size is greater than 256 MB, so USE_UNCOMMON_MIXERS is defined), the built in BiCopter mixer is available, and the servo mix lines should not be necessary.

What target does the Onmibus F4 Corner Pro use? Could it be a resource issue?

[jstremmler]

@ jihlein

Omnibus F4 pro corner has the target OmnibusF4SD on Betaflight.

Ok, maybe your are right and it is a resource issue. So I have decided to start from scratch:

– will reflash the FC with the latest version of Betaflight
– will configure the FC with mixer bicopter
– will take out my soldering iron and connect servo1 to PWM5 = A01 and servo2 to PWM6 = A08
(not so easy to solder- this is why I did the resource remapping. Have marked the soldering pads on the board in blue)

and see how it goes….

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[Kevin_Erik]

Todays progress…

-Speedybee Bluetooth module added. No longer need to plug in the USB to make changes.
-Impossible Tilt Mechanism added from Tricopter-Mini (Its better than the one designed for the Bicopter)
-Mini buzzer added.

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[Kevin_Erik]

@David

Test flight with Speedybee bluetooth adaptor.

Its very stable with just a touch of oscillation during some extreme turns. I’m optimistic that this can be tuned out once Pitch has been properly adjusted.

Note: Erik (7) made the video hence the lack of focus.

[jihlein]

@jstremmler – not to pollute Kevin’s thread, but I think you should be able to use the built in mixer with S1 – S4 as it sure does look difficult to get to the S5/S6 pads. Here’s the IO definition:

DEF_TIM(TIM3, CH3, PB0, TIM_USE_MOTOR, 0, 0), // S1_OUT D1_ST7
DEF_TIM(TIM3, CH4, PB1, TIM_USE_MOTOR, 0, 0), // S2_OUT D1_ST2
DEF_TIM(TIM2, CH4, PA3, TIM_USE_MOTOR, 0, 1), // S3_OUT D1_ST6
DEF_TIM(TIM2, CH3, PA2, TIM_USE_MOTOR, 0, 0), // S4_OUT D1_ST1
DEF_TIM(TIM5, CH2, PA1, TIM_USE_MOTOR, 0, 0), // S5_OUT
DEF_TIM(TIM1, CH1, PA8, TIM_USE_MOTOR, 0, 0), // S6_OUT

The timer usage indicates you should be able to use 1/2 for motors and 3/4 for servos. Don’t know why this is so complicated and convoluted in BetaFlight, but I think the necessary resource cmds would be (typing from memory here):

resource motor 3 none
resource motor 4 none
resource servo 1 A03
resource servo 2 A02

Like I said, not straight forward – hope this helps some…..

[jihlein]

@Kevin_Eric – I like your antenna routing solution, may have to copy that!

[Kevin_Erik]

Made an animated GIF of all the ROLL tuning variations I’ve tried today.

Before Roll tuning (45-20-15):

After Roll tuning (26-8-45):

As you can surmise, only Roll is being adjusted and compared. Should do Pitch tomorrow if the weather is nice. Roll values 22-8-45, 24-8-45 and 28-8-45 were also nice but i went with the mid value thinking the copters response would be better.

Kevin

[Kevin_Erik]

@jihlein The Extra large zip-ties help stabilize the copter during take-off and landings. Keeps it from wobbling over to one side so i highly recommend using that as well.

The Speedybee Bluetooth adapter is AWESOME!

I can change PID’s and Filters in the field. All with the power attached and only an iPad to carry. (Disarmed) It’s 8-10 dollars and so so handy! Wish there was dRonin support with it but they don’t have the market saturation yet to make other platforms worth investing in.

https://www.speedybee.com/bluetooth-uart-adapter/

[jstremmler]

@jihlein
sorry for disturbing Kevin’s thread again, but…

this is where I started to keep it simple stupid, which in follow up led to the described behavior……
simply does not work!
But finally soldering small silicon wires to M5 and M6 solved the problem. Everything is working now and I can do a maiden flight.

[jihlein]

@Kevin_Erik

I use bluetooth all the time to setup dRonin. Have to use the GCS on a laptop which isn’t as convenient as an iPad, but it works.

@jstremmler

Can’t argue with success, hope the maiden goes well.

[Kevin_Erik]

@jihlein

Can you link how Bluetooth is setup?

Today i ran over 100 mini flights (30-45 seconds) to find the right Pitch settings. Thus far no luck as there is too much interplay between the Pitch and Yaw. At best i can choose the best setting from today and then tune Yaw, coming back to Pitch for fine tuning.

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