ROBOTIC GRABBER

ROBOTIC GRABBER

DESIGN PROJECT

Spring 2026

DESIGN PROJECT

Spring 2026

Prototyping, 3D Printing, CAD, Electronics, HTML, Sensors

SUMMARY

In my introductory robotics course, I worked with a partner to create a grabbing robot with gears and linkages, actuated by a stepper motor. The robot had to be held by only the motor casing, and be able to lift an irregular shape—in our case, a small figurine. For our robot, we focused on creating a design that was modular and could be easily modified with no glue, tape or any other adhesives.

Initial Linkage work

Initial linkage work

CAD DESIGN

As this was my first experience creating a four bar linkage, I made sure to test different designs and lengths in onShape, giving me time to experiment with arm lengths and link styles. We used doubled linkages for stability, while leaving the arm thin to reach under the figure more effectively.

In our fabrication, we started simply, testing gears with single arms before moving to create a mock-up of our final design, without any of the hardware mounted.

CAD DESIGN

As this was my first experience creating a four bar linkage, I made sure to test different designs and lengths in onShape, giving me time to experiment with arm lengths and link styles. We used doubled linkages for stability, whille leaving the arm thin to reach under the figure more effectively.

As this was my first experience creating a four bar linkage, I made sure to test different designs and lengths in onShape, giving me time to experiment with arm lengths and link styles. We used doubled linkages for stability, while leaving the arm thin to reach under the figure more effectively.

In our fabrication, we started simply, testing gears with single arms before moving to create a mock-up of our final design, without any of the hardware mounted.

Initial gear test

First linkage test

Initial Grabber CAD

Initial Grabber CAD

CODING AND ELECTRONICS

We fabricated the arm on this mount and coded it to have an opening and closing mechanism (code linked below.) The raspberry Pi was controlled by a flask file on desktop, which consisted of two buttons that moved the arms 90 degrees.

Demonstration of grabber arm

Code Download Link

FINAL PROTOTYPE DESIGN

Our final prototype featured a clear acrylic stand mounted on top of the gears to allow us to hold the motor casing. We mounted the H bridge using screws, while the raspberry pi was fit with low tolerances.

Final prototype

Initial linkage work

Final prototype

Initial linkage work

Initial linkage work

Demonstration of grabber arm

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