Angel Sanchez Llamas
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Completed

Robotic Construction Arm

A proof of concept for a robotic arm that places wall elements in post-disaster relief. I built it in a one-week prototyping cycle, then redesigned the gripper until placements went from rarely working to working reliably.

Program
Transfer Pre-Engineering Program
Focus
Torque sizing, gripper design
Timeline
Jul – Aug 2026
Photo: arm placing a wall element
86.7%
Placement success with custom gripper (up from 6.7%)
2 lb
Design payload for torque calcs
1 week
Print, assemble, and wire to working proof of concept

The problem

After a natural disaster, rebuilding shelter fast matters. Our team built a proof-of-concept arm to place wall elements, starting from an open-source design and adapting it for the task.

Design decisions

Verify servos against payload torque

Question
Can the servos hold and move a 2 lb payload?
Method
Calculated the torque at each joint for a 2 lb payload and checked it against the servo specs.
Outcome
Confirmed the servos were adequate before committing to the build.

Redesign the gripper for stability

Question
Why were most wall placements failing?
Method
Identified gripper instability as the cause, then designed and 3D-printed a custom gripper. I tested each design over 15 trials.
Outcome
Success rose from 1 in 15 to 13 in 15.

Build & test

CAD: custom gripper
Custom gripper design.
Photo: stock vs custom gripper
Stock gripper next to the custom one.
Video / GIF: placement trial
A wall placement trial.

What I learned