Alexander Loker · Portfolio

I've been collecting vinyl for 2 years now, and listening to music for many more. I love music, especially indie rock, hard rock, indie music as a whole, and some melodic hip-hop.

Here is my vinyl collection: Beabadoobee: Beatopia; Muse: Origin of Symmetry, The Resistance; Nas: Illmatic; Oasis: Heathen Chemistry; Radiohead: Pablo Honey, The Bends, In Rainbows; Smashing Pumpkins: Siamese Dream, Adore; Sundots: Honeyspot, room; The Strokes: Room on Fire, The New Abnormal; Tyler, the Creator: Flower Boy, Call Me If You Get Lost; A$AP Rocky: AT.LONG.LAST.A$AP; and more!

If you're interested, I would love to chat with you about music, or robotics, reach out at: lokeralexander@gmail.com

Subassemblies · In Depth

⚠ Due to the assembly being still in progress, descriptions may be incomplete/unavailable.

Base

Overview

The base consists of two main features and their connectors: an electrical housing-framework, and the omniwheels.

Omniwheel Design

The omni-wheels were developed with three key features in mind: Functionality, quiet movement and a compact design. Since the robot is to serve as a soothing therapeutic companion, it is important that the movement of the robot does not disrupt the user during their interaction. The 55 millimeter diameter of the rim plate was judged to be appropriate such that the complete design could have a small stature as the entire robot was further scaled from that single decision.

Sixteen rollers were fitted into the omni-wheels to achieve quiet movement as they maximized the time a roller was in contact with the floor at a given moment. TPU was chosen as the material to manufacture the wheels due to its renowned elasticity compared to PLA, PETG, and other printable materials available at my University. A motor hub attaches to four rim plates on each side via interference fit with a tolerance fit to the motor shaft, and is pinned with a washer for the best long-term hold. An additional pin runs through holes between each "leg" of the rim plates, on which a roller is placed loosely. Due to gravity, the rollers make a strong contact with the ground whilst remaining disconnected from the plate itself, thus allowing for full rolling capability.

Electrical Housing & Framework

The rest of the base is structured to allow for proper electrical housing. An elevated interference fit accepts the standoffs of the Raspberry Pi, and a dedicated space fits a waffle-board for the Pi Pico and motor boards. Additionally, blocks printed separately sit above the motors and hold them down via the frictional force of the interlocking space, with an extrusion pressing against the omniwheel hub to keep each wheel firmly in place.

Shell

Overview

The shell is composed of arm housings, a speaker, four microphones and a camera. These components help accomplish the overall purpose of the robot.

Assembly & Structure

To aid in assembly, the shell is cut into four parts, each carrying holes for square-shaped and L-shaped mounting brackets. The square-shaped brackets are used to attach each of the parts to each other whilst the L-shaped brackets are used to attach the shell to the base.

Microphones

For the microphones, a grommet-insert sound decoupling system was created alongside a housing for further noise reduction from the inside of the shell.

Speaker

An angled extrude was designed from the inside of the shell, with four mounting holes for screws alongside a grille to allow for clean audio output from the speaker.

Camera

A simple extrusion below the intended hole of the camera module was made with holes allowing for a pin-in placement of a back-wall.

Lessons Learned & Design Challenges

In general, creating the shell taught many useful skills: different patterns (such as fill for the grille), how to create any angled plane, how to design for long-term stability, and most importantly how to optimize a design both aesthetically and space-wise.

As described in the base section, the wheels are approximately 55 mm. This led to a shell and head design that was far too large, requiring a full redesign: I was forced to move every component, introduce systems such as the grommet-insert above, and create novel solutions to accommodate for the reduced space.

Head

Overview

The head consists of three main components: a shell, an LCD screen, and a connector to the main body.

Connection to Main Body

The head is connected to the main body via a matching-fit which locks into place on the top of the body. This design choice allows for easy detachability and reliable securement of the head.

The Redesign

For reference, pictured below is the previous final design of the head.