Week 15 — System Integration

This week, I turned Loco Pik from separate working modules into one complete robot. I planned the internal structure. I organized the electronics into layers. I also tested whether light, movement, and AI interaction still worked after assembly.

Project area

System integration
Mechanical packaging
Electronics layout
Assembly logic
Integrated testing
Failure modes
Repair and lifecycle

Key outputs

I made a system integration plan for Loco Pik.
I drew a hand-drawn system wiring sketch.
I created an exploded CAD overview of the packaging.
I analyzed the packaging layer by layer.
I prepared the first printed assembly set.
I documented the assembly logic and internal stacking method.
I tested the integrated LED, movement, and AI functions.
I reflected on failure modes and repair needs.
I wrote an AI use statement.

Overview

This week's assignment asked me to design and document the system integration for my final project.

My final project is Loco Pik, a small emotional desktop companion robot. Loco Pik reacts through light, sound, movement, and AI voice interaction. In earlier weeks, I tested these functions as separate experiments. This week, I focused on making those functions work as one compact and stable object.

The main challenge was not a single module. The real challenge was the whole body. I needed to fit the shell, servos, speaker, LED, battery, control electronics, and sensors into one small robot. I also needed to keep the robot testable and repairable.

Assignment

The individual assignment asked me to design and document the system integration for my final project.

For Loco Pik, I documented the integration plan, CAD evidence, sketch evidence, packaging method, and internal assembly logic. I also documented tests that show the robot working as one complete system.

Checklist

Status	Checklist item	Evidence on this page
Yes	Made a plan for system integration for the final project.	The overview, packaging strategy, assembly logic, test evidence, and failure mode reflection document my integration plan.
Yes	Documented the plan with CAD and/or sketches for system integration.	The CAD and Sketch Documentation section includes my hand-drawn system sketch, exploded CAD overview, first printed assembly set, layer planning images, and final layer design images.
Yes	Implemented methods of packaging.	The layered packaging strategy shows how I arranged, stacked, and enclosed the internal parts inside the body.
Yes	Designed the final project to look like a finished product.	The packaging strategy hides most electronics inside the shell. It also supports a compact, rounded, and integrated appearance.
Yes	Documented system integration of the final project.	This page documents the relationships between the shell, structural layers, electronics, power, motion, light, sound, and AI interaction.
Pending	Linked to this system integration documentation from the final project page.	I will complete this after I add a direct link from `final-project.html` to `week15.html`.

CAD and Sketch Documentation

I first mapped the system as a hand-drawn diagram. This diagram helped me study the relationship between the controller, servo driver, four servos, amplifier, speaker, LED, camera, ToF sensor, NFC, and battery. I used it before deciding the final internal layout.

System integration sketch

After I sketched the system map, I translated the idea into CAD. The exploded overview helped me see the shell and internal layers as one stacked structure. It also helped me avoid treating the modules as loose parts.

Exploded CAD overview

First printed assembly set

Layered Packaging Strategy

I divided the internal structure into three functional levels. This made the system easier to understand and assemble. For each level, I first made a component planning diagram. I then developed the final structural design. This process helped me move from planning to a more manufacturable packaging solution.

Level 1 — component planning

This image shows the planned component allocation for Level 1. I used this diagram to decide which parts belonged in the lowest layer. Level 1 handles movement, sound output, distance sensing, and bottom light feedback.

Level 1 — final layer design

Level 1 final structural design — This drawing shows the final structural design for Level 1. The lower layer supports the servo motors. It also integrates the speaker, ToF sensor, and LED into the packaging system.

After I defined the component allocation, I developed the final structure for Level 1. This layer includes the mounting logic for the servo motors. It also holds the speaker, ToF sensor, and LED. Level 1 forms the lower functional platform of the robot.

Level 2 — component planning

This image shows the planned component allocation for Level 2. I placed the battery and PCA9685 servo driver in the middle layer. This placement keeps power distribution and servo control clear between the lower and upper layers.

Level 2 — final layer design

Level 2 final structural design — This drawing shows the final structural design for Level 2. The middle support plate holds the battery and PCA9685 servo driver. It works as part of the stacked packaging structure.

After component planning, I designed the final structure for Level 2. This layer supports power and actuation. It provides space for the battery and servo driver. It also separates the lower motion layer from the upper control layer.

Level 3 — component planning

This image shows the planned component allocation for Level 3. I placed the main control electronics in the upper layer. This position makes programming, wiring, and debugging more accessible.

Level 3 — final layer design

Level 3 final structural design — This drawing shows the final structural design for Level 3. The upper control plate supports the ESP32-S3, custom PCB, and MAX98357A amplifier within the final packaging system.

After I defined the component placement, I developed the final structure for Level 3. This layer works as the control center of the robot. It also provides the mounting surface for the main electronics.

Assembly Logic

I assembled the internal system as a layered stack from bottom to top. This packaging strategy organizes the internal space. It also makes the system easier to assemble, understand, and repair.

I prepare the lower structure and mount the four servos in Level 1.
I install the speaker, ToF sensor, and WS2812B light on the lower layer.
I place the battery and PCA9685 servo driver in Level 2.
I install the Seeed XIAO ESP32-S3, custom PCB, and MAX98357A on Level 3.
I route the wires between the three levels and keep them away from moving parts.
I close the stacked structure inside the outer shell and test the complete robot.

This layered assembly method also helps with repair. It does not treat the inside as one crowded space. Instead, it separates motion, power, and control into clearer zones.

Integrated Test Evidence

After I planned the packaging, I tested the integrated robot as one system. These tests were important. A module can work on the bench but fail after I enclose it inside the body.

LED feedback test

This video shows the integrated LED feedback test after packaging. The test checks the brightness, direction, and emotional glow effect of the WS2812B light inside the final body.

Movement test — open assembly

This video shows the movement test in the open assembly state. The test checks servo alignment, leg clearance, and the basic stability of the internal motion system before I close the shell.

Movement test — with shell installed

This video shows the movement test after I installed the shell. This test is important for Week 15 because it shows that the motion system still works after packaging.

AI interaction test

This video shows the AI interaction test in the complete robot system. The test shows that communication, audio output, sensing, and control are integrated. They no longer exist only as separate experiments.

Failure Modes

I also considered what might go wrong after integration. This helped me think beyond a working prototype. Loco Pik also needs to survive assembly, repeated testing, and repair.

Failure area	Possible problem	My consideration
Mechanical	Legs bind against the shell, servo horn loosens, or the shell cracks.	I leave enough clearance, center the servos before assembly, and avoid thin stress points.
Wiring	Wires are pulled, scratched, or pinched during assembly or movement.	I separate wiring from moving areas and keep enough slack for repair.
Power	Voltage drops reset the ESP32 when servos or LEDs draw high current.	I keep a clear power path, use common ground, and plan for current spikes.
Software	Commands overlap or the robot stays stuck in one state.	I use simple state recovery and test each combined behavior after packaging.

Repair and Lifecycle

Loco Pik should not become a sealed object after assembly. I still need to adjust it because it is a prototype. I need to reopen the body, check the connectors, replace a servo, or update the control board.

The layered structure supports this repair approach. It separates motion, power, and control into clearer zones. This makes the robot easier to understand and maintain. It also improves the reuse value of standard parts, such as the servos, battery, ESP32-S3, and amplifier.

Link to Final Project

I also need to add a direct link from my final project page to this Week 15 documentation page. This link will complete the checklist.

Suggested final project link: <a href="./assignments/week15.html">Week 15 — System Integration</a>

AI Use Statement

I used ChatGPT to help organize and rewrite the English text for this Week 15 page. ChatGPT helped me structure the documentation around the Fab Academy checklist. It also helped me connect the writing to my CAD, assembly, and testing evidence.

The project idea, design decisions, packaging logic, CAD development, and tests are my own work. I reviewed the AI-assisted writing before publishing it. I also edited the text to match my own process.