Robotic Arm

Day 15 – Robotics Arm Project

Time Worked: 2.5 hours

Today I finalized the bill of materials (BOM) for my robotic arm project and confirmed that all of the required components had been selected. I replaced several Amazon.com items with Amazon.ca alternatives to reduce shipping costs and added a 5x20mm inline fuse kit to protect the ESP32. I also verified that my selected wire and MG90S servos matched my design requirements, so no CAD changes are needed. By the end of the session, the project cost was estimated at $257.10 CAD, and the planning stage was essentially complete.

Next Steps:

• Make the final CAD improvements.

• Apply for the project grant.

• Order the parts once funding is approved.

• Begin the physical build after the parts arrive.

Day 14 — Robotic Arm Project
Time spent: 2.5 hours
Today I worked on creating an animation of my robotic arm to better visualize how all of the joints move together before building the physical prototype. I explored several approaches, including exporting the CAD model for simulation in PyBullet, but ran into issues with the assembly not exporting correctly due to missing joint definitions and material properties. Instead, I used Onshape’s Gear Relation feature to synchronize the movement of multiple joints, allowing me to create a smooth animation driven by a single input. This gave me a simple way to demonstrate the arm’s motion and better understand how the overall mechanism behaves. Next, I’ll continue refining the CAD assembly, prepare the design for 3D printing, and complete the remaining project documentation.

Day 13 — Robotics Arm Project
Time spent: 3 hours
Today I shifted my focus from designing new parts to improving and validating the existing CAD model. I reviewed every component of the robotic arm, corrected several design issues, and refined parts to improve their fit and overall manufacturability. I also planned the wire routing for the arm, making sure each joint would have enough slack for its full range of motion while reducing the risk of wires being pinched during operation. To finish the session, I began preparing the arm for simulation by exporting the assembly from Onshape using the onshape-to-robot exporter. During this process, I discovered that my assembly mates and material properties still need to be configured correctly before the robot can be successfully simulated in PyBullet. Next, I’ll fix the assembly mates, assign materials to every part, and begin testing the robotic arm in simulation.

Day 12 — Robotics Arm Project

Time spent: 2 hours

Today I finished troubleshooting the remaining gear meshing issues and completed the full CAD assembly of the robotic arm. After correcting both the gear center distance and tooth alignment, the gears meshed consistently throughout their full range of motion. With those issues resolved, the entire assembly is now functional. The base, shoulder, elbow, wrist, and gripper all move as intended, and the gear-driven parallelogram gripper operates correctly. Next, I’ll perform a final review of every part by checking dimensions against the actual hardware specifications, make any final adjustments if needed, and finish the bill of materials before preparing the design for manufacturing.

Day 11 — Robotics Arm Project

Time spent: 4 hours

Today’s focus was on finishing the robotic arm’s gripper. After working through several design and assembly issues, I completed a gear-driven parallelogram gripper that keeps the jaws parallel as they open and close. Most of the session was spent troubleshooting gear meshing and assembly constraints. After adjusting the gear alignment and correcting the center distance, the mechanism operated smoothly. I also removed an unnecessary assembly constraint that was causing conflicts, allowing the four-bar linkage to function as intended. Next, I’ll address the remaining issues discovered during testing, finish the full arm assembly, and continue validating the gripper’s motion before moving on to manufacturing.

Day 10 — Robotic Arm Design

Time spent: 2 hours 25 minutes

Today’s work was focused on designing the robotic arm’s gripper. I finalized the parallel-jaw gripper design after comparing various end-effector options over the past two days. Most of my time was spent positioning the servo inside the gripper housing and designing the gear mechanism that opens and closes the jaws while ensuring everything fit together correctly. Next, I’ll finish the remaining gripper components, verify the gear alignment, and continue completing the full CAD assembly.

Day 9 — Robotics Arm Project

Spent: 4 hours

Today I finished designing the wrist section of the robotic arm and continued refining the overall CAD model. I also spent time researching different claw and gripper designs to determine which type would be the best fit for handling small, lightweight objects. A large portion of today’s work involved revisiting earlier CAD parts to add missing details, verify dimensions, and improve the overall assembly. I also searched for manufacturer dimension sheets to make sure the parts matched the hardware I plan to use. While assembling the base, I ran into a gear meshing issue where the 18-tooth and 24-tooth gears were interfering at certain rotation angles. After checking the gear ratio, module, and alignment, I narrowed the problem down to the center distance being slightly too tight. I’m now testing a slightly larger spacing to provide additional clearance and reduce the chance of binding. Next, I’ll finish testing the updated gear spacing, choose a final gripper design, and continue designing the end effector before completing the remaining CAD work.

Day 8 — Robotic Arm Project

Spent: 1 hour

Today I compared the remaining servo options for the robotic arm and decided to replace the MG996R servos with DS3225MG servos. The DS3225MG provides significantly more torque (about 25 kg·cm), is waterproof, and uses metal gears, all while costing less than the MG996R. Since the body dimensions and mounting hole pattern are very similar, I won’t need to redesign any of the existing brackets. I also spent some time optimizing the CAD model by removing unnecessary material from the arm segments. The goal was to reduce filament usage while keeping strength in the areas that experience the highest loads, such as the joints and mounting points. The CAD assembly is now roughly 80% complete. Next, I’ll continue assembling the remaining components and complete the overall arm assembly before moving on to the next stage of the project.