4DoF Robot Arm

thingiverse

Hello everyone, I'm thrilled to finally share this project as it's my first robot. This is a Robot arm designed for my college robotics assignment, specifically made for serving cake (That was the assignment, yes, oddly specific). Essentially, it's a regular robot arm with a gripper designed to pick cooking tools. Since I was the only team member with experience in 3D modeling, I was assigned the task of designing the robot. It's not a visually appealing design, I admit, but it has some flaws that I didn't correct due to time constraints. Still, I'm proud of it and it should function as intended. The design is optimized for 3D printing with a 25-50% infill in PLA, making it both lightweight and food-friendly. Printing with a dense pattern would be ideal. The only part not meant for 3D printing is the base; I recommend using mechanized wood for this component to add some weight. Now, let's move on to the electronics. This setup is designed to hold Pololu Micro Metal Motors, specifically the HP 6V 994,2218 or similar models, as lower power motors won't be able to lift the arm. For position control, we have two key components. The first is a digital incremental encoder, PEC11R-4220F-S0024, which is a standard encoder - don't let the name intimidate you. The second component is a switch from Omron, used to set the zero position. To ensure that the motors can lift both the robot's weight and the gripper's load, I used gears with a 1:2 ratio. This means the arm won't be extremely fast, but that shouldn't be a significant issue since the encoders have a maximum speed of 60RPM. Moving the motors requires an H bridge, and for control, I recommend using an Arduino Mega due to its ample PWM pins and interrupt supporting capabilities. For power, we suggest using a 7.4 V battery with 5000mAh (in the diagram, it's listed as a 3.7 V / 2000mAh battery due to Fritzing limitations). This would be connected to a step-down converter for efficient power management. As you can see in the diagram, the switches need to be connected to the switch pins on the encoders and ground to set the zero position. This should provide all the necessary information to build the arm yourself. I must say that I'm grateful for this project's existence, despite the challenging circumstances surrounding its creation. If you're willing to take on the challenge, I'd love to hear about any issues you encounter while making this project. Your feedback would be invaluable in helping me improve and refine my designs. Thank you for stopping by!