4-Axis Robotic Arm

Project overview

DIY Custom Robotic Arm: Handcrafted Hardware Controlled Mechanics Executive Overview This project showcases a fully functional multi-axis robotic arm designed, fabricated, and wired entirely from scratch. Built without complex microcontrollers (MCU), programming, or expensive 3D-printing and CNC machinery, this build relies purely on fundamental electromechanical principles. By using hand-cut PVC sheets for the chassis, dual L298N motor drivers, yellow DC BO (Battery Operated) gear motors, standard push-button switches, and rechargeable 18650 Li-ion cells, this project proves that effective robotics can be achieved through clever hardware logic and handcrafted fabrication.1. Mechanical Structure & Chassis Fabrication Materials Used: High-density PVC sheet, fasteners, screws, and manual hand tools (cutter, saw, sandpaper, drill).Handmade Precision: The entire structural body—including the base platform, arm linkages, motor brackets, and end-effector (gripper)—was hand-shaped and fitted from PVC sheets without machine automation. Degrees of Freedom (DoF): The arm features multiple points of articulation driven by yellow BO gear motors: Base Rotation: Allows horizontal swivel movement. Shoulder / Lower Arm: Provides main vertical lifting strength. Elbow / Upper Arm: Enables reach adjustment and vertical pitch. Gripper Mechanism: A rack/linkage assembly that opens and closes to pick up objects.2. Electromechanical & Circuit Architecture MCU-Free Direct Control Logic Instead of using microcontrollers (like Arduino or ESP32) which require complex code and signal PWM, this design uses pure hardware switching logic. Dual L298N Dual H-Bridge Drivers: Two L298N driver modules are integrated directly into the chassis base. Since each L298N driver can control two DC motors bidirectionally, two modules allow control of up to 4 independent BO gear motors. Switch Interface Design:8 Directional Control Switches: Arranged on the front control panel in pairs (forward/reverse, up/down, open/close). Pressing a button sends voltage logic high/low directly to the IN1, IN2, IN3, and IN4 pins of the L298N modules to trigger motor rotation in clockwise or counterclockwise directions.1 Power Switch: Dedicated master SPST toggle/push switch interrupting the primary battery line to safely power the system on and off. Power Supply: Powered by two high-drain 18650 Lithium-ion batteries connected in series (~7.4V nominal to 8.4V full charge). This provides sufficient current to drive the L298N motor drivers and supply steady power to all motors under mechanical load.3. Specifications Summary Component Specification / Detail Structure Material Hand-cut PVC Sheet Control System Hard wired Switch Board (No Microcontroller)Motor Drivers2x L298N Dual H-Bridge ModulesActuators4x Yellow BO (Battery Operated) Gear Motors User Interface8 Push Switches (Motor Direction) + 1 Power Switch Power Source2x 18650 Li-ion Batteries (~7.4V DC)