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Page 144 - Toucpad robotics C11
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    21 st   #Coding & Computational Thinking
                          project 2                                                  Century   #Experiential Learning
                                                                                     Skills
                                                        The Pick-and-Place Robotic Arm
                      Objective: Design and build a small, desktop robotic arm that can pick up a lightweight object from one location
                      and place it at another pre-defined location.
                      Steps of the Solution:
                      1.  Project Planning & Design (Project Management):
                         ∑   Define the Scope: Specify the arm's reach, payload capacity, and the objects it will handle (e.g., a small
                             plastic block).
                         ∑   Component Selection:
                                 Brain: Use a microcontroller (like an Arduino Uno) to control the arm.
                             §
                             §   Muscles: Choose three or four servo motors to actuate the joints (manipulators). A simple gripper
                                 will also be controlled by a servo motor.
                                 Senses: A basic touch sensor on the gripper can be used to detect when it has successfully grasped
                             §
                                 the object.
                             §   Power: A dedicated power supply unit or a suitable battery will be needed to power the servo motors.
                         ∑   Structure: Design the arm's links and a stable base using acrylic for its lightweight properties and ease of
                             fabrication with a laser cutter. The design should follow the principles of a planar open-chain mechanism.
                      2.  Hardware Assembly & Wiring:
                         ∑   Fabricate the Links: Cut the acrylic links and other structural parts from the design.
                         ∑   Assembly: Assemble the robotic arm, attaching a servo motor at each joint.
                         ∑   Wiring: Connect all the servo motors and the touch sensor to the microcontroller.
                      3.  Programming & Control (Fundamentals, Logic, Kinematics):
                         ∑   Manual Control: Write a simple program to manually control each servo motor using a variable or a
                             potentiometer to understand how each joint moves.
                         ∑   Forward  Kinematics (RP or 2R configuration): Manually calculate  the  forward  kinematics for
                             the arm's configuration. This will help you understand the relationship between the joint angles and the
                             gripper's position.
                         ∑   Basic Control Program:
                             §   Step 1:  Write a series of commands to set the joint angles to move the gripper to the pickup location.
                                       For a simple robot, you can find these angles by manual trial and error.
                             §   Step 2: Activate the gripper's servo motor to close and grab the object.
                             §   Step 3:  Set the joint angles to move the arm to the drop-off location.
                             §   Step 4: Activate the gripper's servo motor to open and release the object.
                             §   Step 5: Return the arm to its original starting position.
                         ∑   Object Delivery: Program the servo motor to activate at the destination point to either lift or drop the item.
                      4.  Debugging & Testing (Ensuring Performance):
                         ∑   Calibration: Fine-tune the joint angles to ensure the arm reaches the correct pickup and drop-off locations
                             accurately. This is a form of dynamic error compensation.
                         ∑   Repeatability Test: Run the program multiple times to see if the robot can consistently pick up and place
                             the object in the same location. This is a key measure of a manipulator's performance.

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                  Touchpad Robotics - XI

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