Basic Arm Movements

Dive deeper into programming your robot arm with Python, focusing on creating basic yet essential movements and sequences.

By Kevin McAleer,    3 Minutes

Introduction to Arm Movement Sequences

Now that you’ve learned the basics of controlling servos with Python, let’s apply these skills to create a series of basic yet fundamental movements for your robot arm. This lesson will guide you through programming your robot arm to perform tasks such as reaching out, grasping an object, and retracting.

Planning Your Movements

Before coding, it’s essential to plan the sequences of movements your robot arm will perform. Consider the following steps for a simple task like picking up an object:

1. Reach: Extend the arm towards the object.
2. Grasp: Close the end effector (e.g., a claw or hand) around the object.
3. Retract: Bring the object back towards the base.

Example Code: Reaching Out

Let’s start by programming our robot arm to reach out. We’ll need to adjust the angles of the servos responsible for the arm’s extension.

def reach_out():
    set_servo_position(base_channel, base_forward_position)
    set_servo_position(shoulder_channel, shoulder_down_position)
    set_servo_position(elbow_channel, elbow_straight_position)
    time.sleep(2)  # Wait for the arm to fully extend

Example Code: Grasping an Object

Programming the end effector to grasp an object involves closing the claw or hand by moving its controlling servo to the required position.

def grasp_object():
    set_servo_position(claw_channel, claw_closed_position)
    time.sleep(1)  # Allow time for the end effector to close

Example Code: Retracting the Arm

Finally, retract the arm by reversing the extension movements. Ensure the object is securely grasped before retracting.

def retract_arm():
    set_servo_position(elbow_channel, elbow_bent_position)
    set_servo_position(shoulder_channel, shoulder_up_position)
    set_servo_position(base_channel, base_start_position)
    time.sleep(2)  # Wait for the arm to fully retract

Putting It All Together

Combine the functions above into a sequence to perform the complete task.

def perform_task():
    reach_out()
    grasp_object()
    retract_arm()
    # Place additional movements or tasks here

perform_task()

Experimenting with Movements

Experiment with the servo positions and timings to refine your robot arm’s movements. Each robot arm will be unique due to differences in construction and servo characteristics, so adjustments are expected.

Conclusion

You’ve now programmed your robot arm to perform basic tasks, marking a significant milestone in your robotics journey. Continue to build upon these foundations by creating more complex sequences and exploring additional functionalities for your robot arm.

Lesson Assignment

Create a sequence that involves moving an object from one location to another. Document the servo positions and timings used, and reflect on the challenges faced and how you overcame them.