Hi, I’m trying to see your project
But, there was an error on the code and i can’t solved it.
I'm sorry, but can I get some help from you?

Is it possible to achieve a similar result, but instead of using an encoder to get the position of the pendulum, use a gyro like the BNO055?

I'm trying to create a balancing RC vehicle that uses a reaction wheel to keep itself upright, but struggling to find a good motor/ESC pair, and came across the Arduino FOC project which seems promising. From what I can tell, it includes torque control, which is exactly what I would need.

hello

I got a foc board and was looking to try out an inverted pendulum.
As a first step I'm trying out the 2V motor rotation (beginning of your video), however I don't get the motor initialisation and there is no movement.

Trying to debug this there are a couple of things that seem odd to me:

• when I power the foc shield with 12V, the arduino does not get powered. is that normal? - the foc shield gets a blue led on, so there should be power. the normal Vin pin on the arduino works when I supply it with 5V
• when using the foc library, i don't seem to be able to get a serial connection, at least i don't see anything printed on it. is that intended? - this works on the arduino normally.
• also in the code you specify pins on the arduino. however i did not find a mapping of which pins connect where on the shield. for example the encoder pins (the 5 solo pins on the board), how do I know which pins they are connected to on the board?
• with older versions of the arduino mega the 2 front most pins on both sides are not connected (SCL/SDA on the right side and GND+IOREF on the left) does the foc shield rely on the IOREF pin?
• on the bldc driver class there is an "enable pin" (default 8) mentioned. However there is no explanation to it. do i need to force this pin to 5V or to GND for the driver to work?

thanks for your pointers

my hardware:
board: arduino mega 1280
motor: https://www.aliexpress.com/item/4001296350749.html
encoder: https://www.aliexpress.com/item/32990323362.html
(it's the first time i'm using this type of encoder, i didn't find any info on pull-up/down, so i didn't solder any of those on the board)

Hi,

I'm using AMT103 encoder for my project as well. I'm here to ask if anyone has the same issue as mine.

I checked the DIP switch of the encoder, it should be the expected PPR number as I set it with the documentation. But still, I cannot get the correct angle value from the sensor.

Hardware: Arduino Uno

When I keep the motor running and get the angle value from the encoder, the value also keeps increasing. But the value is way less than the real angle value. For instance, when the motor rotated half circle, the value I got from the encoder was only around 1 instead of 3.14.

The codes:

#include <SimpleFOC.h>

// digital pins
int encoder_pin_a = 3;
int encoder_pin_b = 2;

Encoder encoder = Encoder(encoder_pin_a, encoder_pin_b, 500);
void doA(){encoder.handleA();}
void doB(){encoder.handleB();}


void setup() {
  // initialize encoder hardware
  encoder.init();
  // hardware interrupt enable
  encoder.enableInterrupts(doA, doB);

  // monitoring port
  Serial.begin(9600);
  Serial.println("Setup ready");
  delay(1000);
}


void loop() {
  encoder.update();
  Serial.println(encoder.getAngle());
}

HELLO SIR
I'm working on your perfect project.
So far, we have been able to successfully control the reaction wheel by lifting it up and standing it up by hand. However, it is not possible to raise the pendulum upward by swinging up. In your code, 40% of the voltage limit is used for swing-up, but even if I use more than 80%, the pendulum does not reach the top with swing-up.
Currently I am experimenting with the reaction wheel of the same weight and size as the pendulum of your project and a 12V POWER SUPPLY. Are there any expected problems?

Hi, I bought the iPower Motor GM4108H-120T and the encoder AMT103 CUI you used, I found there is no way to mount the encoder to the motor. Any advices?

hello
first off, thanks for the amazing documentation on your cool project!! - great work!
looking to build something similar...
there is 1 thing i don't understand in your setup: the foc-shield, as i understand it, does only allow 1 encoder to be connected to it. you obviously need 2. now i know the shields could be stackable, but you don't seem to stack them...
how did you solve that? - repurposing free pins? is that then still compatible with the foc library?
thanks!

The motor makes a mechanical sound at first and does not work.
I would appreciate any help in terms of hardware or software.
The Arduino code used is as follows

// software interrupt library
#include <PciManager.h>
#include <PciListenerImp.h>


// BLDC motor init
BLDCMotor motor = BLDCMotor(11);
// driver instance
BLDCDriver3PWM driver = BLDCDriver3PWM(9, 10, 11, 8);
//Motor encoder init
Encoder encoder = Encoder(A1, A2, 500);
// interrupt routine 
void doA(){encoder.handleA();}
void doB(){encoder.handleB();}


// pendulum encoder init
Encoder pendulum = Encoder(2, 3, 1000);
// interrupt routine 
void doPA(){pendulum.handleA();}
void doPB(){pendulum.handleB();}
// PCI manager interrupt
PciListenerImp listenerPA(pendulum.pinA, doPA);
PciListenerImp listenerPB(pendulum.pinB, doPB);

void setup() {
  
  // initialise motor encoder hardware
  encoder.init();
  encoder.enableInterrupts(doA,doB);
  
  // init the pendulum encoder
  pendulum.init();
  PciManager.registerListener(&listenerPA);
  PciManager.registerListener(&listenerPB);
  
  // set control loop type to be used
  motor.controller = MotionControlType::torque;

  // link the motor to the encoder
  motor.linkSensor(&encoder);
  
  // driver
  driver.voltage_power_supply = 12; 
  driver.init();
  // link the driver and the motor
  motor.linkDriver(&driver);

  // initialize motor
  motor.init();
  // align encoder and start FOC
  motor.initFOC();
}

// loop downsampling counter
long loop_count = 0;

void loop() {
  // ~1ms 
  motor.loopFOC();

  // control loop each ~25ms
  if(loop_count++ > 25){
    // updating the pendulum angle sensor
    // NECESSARY for library versions > v2.2 
    pendulum.update();
    // calculate the pendulum angle 
    float pendulum_angle = constrainAngle(pendulum.getAngle() + M_PI);

    float target_voltage;
    if( abs(pendulum_angle) < 0.5 ) // if angle small enough stabilize
      target_voltage = controllerLQR(pendulum_angle, pendulum.getVelocity(), motor.shaftVelocity());
    else // else do swing-up
      // sets 40% of the maximal voltage to the motor in order to swing up
      target_voltage = -_sign(pendulum.getVelocity())*motor.voltage_limit*0.4;

    // set the target voltage to the motor
    motor.move(target_voltage);

    // restart the counter
    loop_count=0;
  }
   

}

// function constraining the angle in between -pi and pi, in degrees -180 and 180
float constrainAngle(float x){
    x = fmod(x + M_PI, _2PI);
    if (x < 0)
        x += _2PI;
    return x - M_PI;
}

// LQR stabilization controller functions
// calculating the voltage that needs to be set to the motor in order to stabilize the pendulum
float controllerLQR(float p_angle, float p_vel, float m_vel){
  // if angle controllable
  // calculate the control law 
  // LQR controller u = k*x
  //  - k = [40, 7, 0.3]
  //  - x = [pendulum angle, pendulum velocity, motor velocity]' 
  float u =  40*p_angle + 7*p_vel + 0.3*m_vel;
  
  // limit the voltage set to the motor
  if(abs(u) > motor.voltage_limit*0.7) u = _sign(u)*motor.voltage_limit*0.7;
  
  return u;
}

And this is a real picture. Could it be a connection mistake?

Dear Antun,

Thank you so much for this amazing project and it is very inspiring !!

I made a similar system that is almost working (please see https://youtube.com/shorts/L6I1zPEigmI?feature=share), but I don't know to tune the LQR parameters precisely so to make it completely stabilize. Could you please give me some advice? Thanks!

-- Wingman

Hi, i was wandering what part you are using to mount the encoder?
Might just be me who is stupid but I cant see it listed anywhere