Robot SCARA | Cómo construir su propio robot basado en Arduino

La interfaz gráfica de usuario se realiza utilizando la biblioteca controlP5 para el IDE de procesamiento. Con esta biblioteca podemos crear fácilmente botones, controles deslizantes, campos de texto, etc.

Por ejemplo, usamos los controles deslizantes en el lado izquierdo para controlar los ángulos de las articulaciones, y usando los campos de texto podemos ingresar la posición donde queremos que vaya nuestro robot. Con cada acción que realizamos aquí con el programa, enviamos datos a la placa Arduino a través del puerto serie.

if (gripperValuePrevious != gripperValue) {
    if (activeIK == false) {     // Check whether the inverseKinematics mode is active, Executre Forward kinematics only if inverseKinematics mode is off or false
      gripperAdd = round(cp5.getController("gripperValue").getValue());
      gripperValue=gripperAdd+50;
      updateData();
      println(data);
      myPort.write(data);
    }
  }Code language: Arduino (arduino)

Estos datos incluyen los ángulos de las articulaciones, el valor de la pinza, los valores de velocidad y aceleración, e indicadores para saber si hemos pulsado el botón de guardar o el de ejecutar.

public void updateData() {
  data = str(saveStatus)
    +","+str(runStatus)
    +","+str(round(cp5.getController("j1Slider").getValue())) 
    +","+str(round(cp5.getController("j2Slider").getValue()))
    +","+str(round(cp5.getController("j3Slider").getValue()))
    +","+str(round(cp5.getController("zSlider").getValue()))
    +","+str(gripperValue)
    +","+str(speedSlider)
    +","+str(accelerationSlider);
}Code language: Arduino (arduino)

Todos estos datos vienen como una cadena larga en el Arduino. Entonces aquí, primero necesitamos extraer los datos de esa cadena y ponerlos en variables separadas.

if (Serial.available()) {
    content = Serial.readString(); // Read the incomding data from Processing
    // Extract the data from the string and put into separate integer variables (data[] array)
    for (int i = 0; i < 10; i++) {
      int index = content.indexOf(","); // locate the first ","
      data[i] = atol(content.substring(0, index).c_str()); //Extract the number from start to the ","
      content = content.substring(index + 1); //Remove the number from the string
    }
    /*
     data[0] - SAVE button status
     data[1] - RUN button status
     data[2] - Joint 1 angle
     data[3] - Joint 2 angle
     data[4] - Joint 3 angle
     data[5] - Z position
     data[6] - Gripper value
     data[7] - Speed value
     data[8] - Acceleration value
    */Code language: Arduino (arduino)

Ahora con estas variables podemos tomar acciones con el robot. Por ejemplo, si presionamos el botón GUARDAR, almacenamos los valores de los ángulos de las articulaciones actuales en una matriz separada.

// If SAVE button is pressed, store the data into the appropriate arrays
    if (data[0] == 1) {
      theta1Array[positionsCounter] = data[2] * theta1AngleToSteps; //store the values in steps = angles * angleToSteps variable
      theta2Array[positionsCounter] = data[3] * theta2AngleToSteps;
      phiArray[positionsCounter] = data[4] * phiAngleToSteps;
      zArray[positionsCounter] = data[5] * zDistanceToSteps;
      gripperArray[positionsCounter] = data[6];
      positionsCounter++;
    }Code language: Arduino (arduino)

If we click the RUN button, we execute the stored steps and so on.

For controlling the stepper motors, I used the AccelStepper library. Although this is a great library for controlling multiple steppers at the same time, it has some limitations when it comes to controlling a robot like this. When controlling multiple steppers, the library cannot implement acceleration and deceleration, which are important for smoother operation of the robot.

stepper1.moveTo(stepper1Position);
  stepper2.moveTo(stepper2Position);
  stepper3.moveTo(stepper3Position);
  stepper4.moveTo(stepper4Position);

  while (stepper1.currentPosition() != stepper1Position || stepper2.currentPosition() != stepper2Position || stepper3.currentPosition() != stepper3Position || stepper4.currentPosition() != stepper4Position) {
    stepper1.run();
    stepper2.run();
    stepper3.run();
    stepper4.run();
  }Code language: Arduino (arduino)

I still managed to implement acceleration and deceleration with the library, but they are not as smooth as I wanted to be.

Here are full Arduino and Processing codes for this Arduino SCARA robot project:

Wrap up

So finally, once we upload the code to the Arduino, we can run the processing program, connect the power and the scara robot will start moving to its home position.

From there on, we can do whatever we want the it. We can play around manually or set it to work automatically. Of course, we can attach any kind of end-effector and make cool stuff with it. For example, we can even attach a 3D printer hot end to the robot and so make the robot a 3D printer, or attach a laser head and make it a laser cutter. I do plan try these two ideas, so make sure you subscribe to my channel so you don’t miss them in some of my future videos.

Before this video ends, I would like to give you few more notes about this project. I found the robot to be not as rigid as I expected.

I guess the problem is that almost the entire SCARA robot, the Z-axis and the arms are supported only by the first joint. The whole weight and the inertial forces generated when moving, can make quite a stress to base where the first joint is located, and as it’s just a plastic it tends to bend a little bit. Also, these belts are not backlash free so we reduce the robot rigidity with that too. However, I think the overall project is good enough so you to learn how SCARA robots work, and gives you the courage to build one for yourself.

No dude en hacer cualquier pregunta en la sección de comentarios a continuación y consulte mi Colección de proyectos de Arduino.