Arduino 6-DOF Robotic Arm with MG996R Servos and Control it via Bluetooth

This robotic arm uses 6 MG996R servos to control:

1. Base rotation
2. Shoulder movement
3. Elbow movement
4. Wrist pitch
5. Wrist roll
6. Gripper open/close

The arm is controlled wirelessly via Bluetooth (HC-05/HC-06) using SoftwareSerial on Arduino. Each servo receives angle values from the user through a mobile app or Bluetooth terminal.

📡 Working Steps:

1. Power Up:

   • Servos are initialized and positioned to default angles (usually 90° for center).
   • Bluetooth module starts listening for input over SoftwareSerial.

2. User Command:

   • You send a command like 2:130 from a mobile Bluetooth terminal (e.g., Serial Bluetooth Terminal app).
   • 2 refers to the shoulder servo, 130 is the target angle.

3. Command Parsing:

   • The Arduino reads and parses the command.
   • It identifies which servo to control and what angle to set.

4. Servo Actuation:

   • The chosen servo moves to the specified angle using servo.write(angle).
   • This continues in real-time as new commands are sent.

Core Components Used

• Servo.h: Controls standard hobby servo motors.

• SoftwareSerial.h: Enables serial communication on digital pins (used for Bluetooth).

• 6 MG996R servos for different joints of the robotic arm:

  • Base rotation
  • Shoulder
  • Elbow
  • Wrist pitch
  • Wrist roll
  • Gripper

• Bluetooth module (HC-05/HC-06) connected to pins 10 (RX) and 11 (TX).

Code Flow Overview

1. Initialization (setup() function)

bluetooth.begin(9600);
Serial.begin(9600);

• Initializes communication with both Bluetooth and the Serial Monitor.

baseServo.attach(3);  // Attaches each servo to its PWM pin
...
gripperServo.attach(8);

• Each servo is assigned to its corresponding control pin.

moveAll();

• All servos are set to the default mid-point (90°) to ensure neutral positioning.

2. Main Loop (loop() function)

if (bluetooth.available()) {
  char command = bluetooth.read();
  Serial.print("Received: ");
  Serial.println(command);
  handleCommand(command);
  moveAll();
}

• The program continuously waits for input from the Bluetooth module.

• When a character is received:

  • It's printed to the Serial Monitor.
  • It's passed to the handleCommand() function to interpret which joint to move.
  • After the update, moveAll() is called to apply the new positions to all servos.

3. Command Handling (handleCommand() function)

switch (cmd) {
  case 'a': basePos = constrain(basePos - 5, 0, 180); break;
  case 'd': basePos = constrain(basePos + 5, 0, 180); break;
  ...
}

• This function maps each received command to a specific joint movement.
• The angle is increased or decreased in steps of 5 degrees.
• constrain() ensures that angles never go below 0 or above 180, which are the servo’s safe limits.

Command Mappings:

4. Servo Movement (moveAll() function)

baseServo.write(basePos);
...
delay(10);

• Each servo is updated with the current angle value.
• A slight delay (10 ms) ensures smooth transitions and avoids servo jitter.

Working Concept Summary

• The robotic arm receives single-character Bluetooth commands.
• These commands translate into incremental servo movements.
• You can control all six degrees of freedom (including the gripper) wirelessly via a Bluetooth terminal app or controller.

Final Code