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15. System integration

Overview of week 15 assignment

  1. Individual assignment
    1. Design and document the system integration for your final project

1. Individual assignment

A. Triage

This week, I updated my final project plan. With only three weeks left until the final presentation, I decided to simplify the project. I decided to make a mobile pen plotter with an unlimited print area, not a 3D printer.

Key points:

  • The machine will function as a pen plotter instead of a 3D printer.
  • Firmware like GRBL or Marlin won’t be used, as mecanum wheel control will be managed externally and no extruder or spindle control needed for now.
  • I plan to design and build Mecanum wheels, but will use purchased ones if time is limited.

B. System

This mobile pen plotter robot interprets G-code commands sent via serial from a PC. A Raspberry Pi Pico processes the G-code and outputs motor control signals to 4 A4988 motor drivers. 3 limit switches, mounted on each side and at the base of the arm, send a zero signal when triggered, enabling zeroing. The A4988s are powered by a Stabilized 12V 10A Power Supply.

System diagram

system_diagram

C. Mechanical design and mahine design

This is an updated version of the design from the Week 02 assignment. Some changes were made to meet current requirements, while other parts were kept the same to allow for future modifications.

Initially, I planned to mount the PCB inside the frame. However, due to its size, I relocated it to the top of the frame using four M5 bolts. I added 3D-printed enclosure.

enclosure_0

enclosure_1

Detailed design will be documented at Final project - Hardware design.

Also assembly process will be documented at Final project - Assembly and testing.

D. Programming

The programming will be based on the Arduino code on Week 14 assignment, with the following enhancements:

  1. Increase the number of motors from 2 to 5
  2. Map four motors to enable mecanum wheel control for omnidirectional movement
  3. Add a Z-axis motor for pen plotter
  4. Extend compatibility to support additional G-code commands (e.g., G28)
  5. Add limit switches and zeroing

E. Electronics design plan

a. components

The basic electronic components and wiring will remain the same as in the Week 10 assignment, but with an increased number of motors and drivers.

A detailed BOM will be documented in Final project | BOM.

b. PCB design

The PCB design should prioritize modularity and expandability, as my "final" project is not the actual final version.

  1. Support for five A4988 motor drivers mounted via pin headers
  2. XH2.54-4 connectors for stepper motor wiring
  3. Pin headers for endstops
  4. Pin headers for Raspberry Pi Pico
  5. Additional pins for:
    1. Future input device testing
    2. Expanding with more motor drivers later

F. Project manegement

Please click "See the board"

2. Files

  • WIP Fusion file in the middle of this page

Afterthoughts

  • "I'm afraid of time"