Segway build.

[ovaltineo]

Hi Ovaltino...and well done..you've beaten me to a working segway!!

My first version took 3 months before I got it going - main problems were glitches on my custom motor controller and getting motor and wheel aligned.

You are using the same motors, wheels, motor controllers and I presume Arduino Mega?

What giro/accelerometer are you using..we have the MPU6050.

Yes, I now am using exact same components. But I am using 2X MPU6050. One for board tilt, and one for steering. I think it is much better than using a potentiometer, and at only $4 from ebay, not much more expensive.


I will post my code, but first I will change it to work with the BTN7960 controllers.

 

[ovaltineo]

For those people who think the software must be incredibly complex - it is not. Here's the main loop section of the code which is quite simple.


// Compute motor and steer:

board_accel = getBoardAccel();
board_gyro = getBoardGyro();
board_angle = complementaryFilter(board_accel, board_gyro);
speed = computePID(board_angle, board_gyro);
motor = motor + speed;

steer_angle = getSteerAngle();
steer = steer_angle * STEER_MULTIPLIER;

left_motor = motor + steer;
right_motor = motor - steer;

control_motors(left_motor, right_motor);

 

[BillJ]

Yes, very simple but what's in complementaryFilter() and computePID() ?

 

[ovaltineo]

The theory behind complementary filter and PIDs are a bit complicated , but the actual implementation is also quite simple.


float complementaryFilter(float accel, float gyro)
{

static float filtered_board_accel = 0;
static float angle = 0;


filtered_board_accel = lowpassFilter(filtered_board_accel, accel, ACC_FILTER);
angle = TAU * (angle + (gyro * dt_micros/1000000.0));
angle += (1-TAU) * filtered_board_accel;

return angle;​

}

float computePID(float board_angle, float gyro)
{

float result;

integral_angle += board_angle;
result = ((P * board_angle) + (I * integral_angle) + (D * gyro));
return result;​

}

 

[ovaltineo]

Unfortunately, the coding is beyond my very limited knowledge...I used to be good with BASIC!!!....so I'm waiting on my colleague to do a recode but we live a long way from each other which makes it more difficult.

How's your code going Gerrymoore? I found this code that suits our hardware. I got mine working with the BTN7960 and will post my code when I get around to updating the clean version of my code.

Let us know what problems you are facing so we can help you out.

 

[gerrymoore]

Hiya...the code you've highlighted was done by the guy who was helping me!! It didn't work too well unfortunately but probably needs tweaking and we just didn't have time. We also had some trouble with the chains and sprockets...either too tight and binding or loose and sloppy....I don't think there is enough dsitance between the motor and wheel sprocket but it would be a whole chassis redesign and I just haven't got time at the moment as trying to get my CNC profiling business off the ground.

If you don't mind, I would love a copy of your completed code to try...pity you're a bit far away as well

 

[Robotstar5]

If you don't mind, I would love a copy of your completed code to try...pity you're a bit far away as well

Business trip required?

 

[ovaltineo]

I can see a few things wrong with your code or maybe it's just not the latest version.

One problem is that it is using the X axis of the accelerometer with the X axis of the gyro. If oriented normally, it should be x axis of the accelerometer with the y axis of the gyro.

Second problem is that it is changing the PWM pulse width instead of changing the PWM duty cycle.

The P and D values also look very large.

Yeah, I think I better give you my code. Just need some time to clean it up.

 

[gerrymoore]

Thanks Ov...I look forward to it

 

[ovaltineo]

I've cleaned up my code and even added support for a potentiometer in the steering, but I cannot upload non-image files in this forum . So if you want to get my code, visit this other forum where I've posted my code. You can also see how two other guys are building their Segways. You will need to register in that forum to be able to download the file.

 

[gerrymoore]

Thanks a lot Ovaltineo...I'll take a ganders later on. Segway has taken a bit of a back seat at the moment while I try and repair my unwell CNC machine

 

[Dream_IN]

Too..gerrymoore
Excuse me!
Can you help me?
I want to code arduino.
I build Segway project finish at University,and guidance.
Thank You Very much.

 

[gerrymoore]

Sorry..can't help as I never got it to work myself...try the Arduino forums........

 

[Dream_IN]

Sorry..can't help as I never got it to work myself...try the Arduino forums........

thank you very much

 

[Dream_IN]

How's your code going Gerrymoore? I found this code that suits our hardware. I got mine working with the BTN7960 and will post my code when I get around to updating the clean version of my code.

Let us know what problems you are facing so we can help you out.

Too...ovaltineo

Excuse me!
Can you help me?
I very want to code arduino.
I build Segway project finish at University,and guidance.
Thank You Very much.