Robotic Arm Popeye MK1

thingiverse

This is an experiment that I'm not sure you should try. It was just a school project for my 8th grade class, and I didn't have much time to work on it. Next up, I'll be building Popeye MK2. When creating my robotic arm, the first step I had to take was deciding what type of electronic components I needed for the arm. I decided to use a Raspberry pi 3 B+ microcomputer as the main computer of the arm. This component would send instructions to the motors and receive data from the controls. I chose the Raspberry pi because my mentor suggested it, and I've read many good reviews about its flexibility for various projects including robotic arms. The "pi" also has many GPIO pins to connect multiple motors, controllers, and sensors. Next, I had to choose what type of motors I would use. My three options were servos, stepper or DC motors. With the servo you can decide exactly how far it rotates. The stepper is precise but doesn't know where it's rotating. The DC motor isn't used in this project because it isn't precise in its rotations. I used three Nema 17 stepper motors for rotating the heavier parts while two smaller 5 volt stepper motors controlled rotating the gripper arm piece. One small servo was used for closing the gripper. To connect and power the motors, I needed a separate motor driver board that would attach itself to the GPIO pins on the raspberry pi. I bought two "motor hat" chips that had 2 stepper motor ports and 4 servo ports. Then I got two analog joysticks to control the arm. I also used two specific converter chips to convert the signal coming from the joystick to a signal that the raspberry pi could understand. I designed the parts on a computer graphics program called Tinkercad and used our 3D printer to create the parts. I used a wooden base because it would be too big to print. Next, I wrote the software code on the raspberry pi using the python coding language. First, I wrote a code that reads the coordinates from the two joysticks and displays it on the screen. Then I modified that code so based on the coordinates it receives, it moves a specific motor in one direction. For the base, I used a round wood base with bearings and attached a motor. The motors shaft went through a hole and is attached to the larger base. The rest of the arm is composed of my custom 3D printed parts and motors. The gripper is the only part of the arm that isn't my own design. When I tested the motor, it wasn't strong enough to lift the arm. To fix this, I needed a counterweight to balance the arm so the motor could handle the weight of the rest of the arm. For my counterweights, I'm using screws and adding washers until the arm is balanced. For rotating the base, I'm using a geared motor that turns a gear on the edge of the base of the arm. The base of the arm is attached to a bigger base with a Lazy Susan bearing. I used a 5 volt stepper motor with its own driver to rotate the gripper. The gripper uses a servo motor to open and close. I soldered many extension wires so the arm could extend freely. Finally, I finished the code so that all the motors were involved with the joysticks. The arm is done, and I named it Popeye after the cartoon character. I'm planning to make an enclosure for the hardware components and the joysticks. Materials: 3 Nema 17 Stepper Motors 1 5 volt stepper motor and driver 2 motor hats for raspberry pi 1 Raspberry pi 3 B+ (you need a monitor, keyboard, mouse, and power supply to use) wires bolts and screws for assembly and counterweights 1 lazy susan bearing 2 joysticks and analog converters