ENGINEERING JOURNAL

Jingyan Ling

06/27/2019 (Thur)

• Compile OldRoCo repo
  • Record of modification:
    • ++line 8 of vstart.sh
    • --> pip install -r requirements.txt --user
• Export paperbot dxf file : graph-silhouette.dxf to OnShape
  • Record of Tips:
    • Onshape does not read dxf file as its own saved unit. Manual settings needed when import.
    • 
• Draw circuit diagram as CAD on Onshape
  • Multiple connection approaches:
    • Cross shape of 0.039 in
    • Cross shape of 0.049 in
    • Octangular shape of 0.049 in
    • 
    • 
  • Note and issue:
  • Octangular shape is the best connection approach so far, but none of approach has stable conductivity. More research is needed.
  • Scratches can be made easily when attaching microcontroller to the sheet. Potential disconnection may occur due to such scratches on metal layer.
• Export 2D CAD drawing with PCB to SVG for silhouette cameo
  • Record of Tips:
    • OnShape unit need to be consisted with unit setting in Inkscape (default: mm)
  • Plugin Inkscape-silhouette cannot take multiple types of trace for cutting.
    • Different trace (especially cut and etching) need to be sent separately. Use coordinate tool of Inkscape to ensure separated cuts have same origin.
  • TODO:
    • Cut and etching from same Inkscape file

06/28/2019 (Fri)

Connection and fabrication approach confirmed !

• Confirm that copper tape has better conductivity than aluminum sheet when attaching microcontroller pins through H-shape cut

  • Copper tape is harder to be scratched, which provides less risk of disconnection during assessmbly.

• Etching on copper type isolates connections

• Research on PCB editor

  • EAGLE
    • EAGLE cannot import .pcb file
    • svg can be exported but not imported
    • Custom library needed if doing schematic design
  • KiCad
    • Can import .pcb file
    • svg can be exported but not imported
  • LayoutEditor
    • support multiply file type
    • svg can be exported with different color makers as multiple layers
    • include open-sourced auto-router freerouting

• Auto-routing package:

  • TopoR
  • Python-PCB
  • FreeRouting

• Approaches:

  • A. convert SVG/DXF file to schematic/board design of PCB. Use KiCAD or EAGLE to do auto routing.
  • B. develop algorithm on auto routing for single layer svg/dxf file. (path finding problem)

Approach A

• Use regular shape board for PCB in EAGLE/KiCAD

  • image processing: divide alternative shape of paperbot to multiple rectangles (openCV)

  • Pull required connections and place additional header pins around edges of each rectangle

• Make each connection pin to be two parallel connections so auto-router does parallel trace for each wiring.

  • Etching a pair of parallel trace provides isolation, and leave the space between traces to be conductible.

• Build Library for schematic design

  • Schematic design helps with router to know desired connection
  • Additional header pins at each side of kink mark

06/29 & 06/30/2019 (Sat & Sun)

Approach B

• Potential needed functions of packages

  • A package draws on DXF file through script
  • A script that pulls out pins' coordinate on paper chassis
    • Or a image process package (OpenCV) that reads pins' coordinate on paper chassis
  • A package solves multi-node path finding problem*

Record of Research

• Python Pathfinding package:
  • pathfinding
• Python DXF editor:
  • ezdxf
  • dxfgrabber
    • Note: able to grab simple geometry from file
  • sdxf
• Going through tutorials of ezdxf
  • All lines on paper spacelayer0

07/01/2019 (Mon)

• Continue the dxf processing with 'graph-silhouette.dxf'

Record of tips:

• Put circuit design on a new layer of dxf drawing

  • check doc about layers here

• Use block feature to draw similar pattern

  • check doc about block here

• Blocks are symbol in Inkscape. Convert symbol to path

  • Edit > Clone > Unlink Clone (Shift+Alt+D), and you have a group, ungroup (Object > Ungroup, or Shift+Ctrl+G) and edit

• Convert text to path

  • Path combine (Ctrl+K)

• Test fabrication with different drawing settings

  • Layers can be cut separately but toggling visibility
  • Set cuts with same intensity and feedrate on same layer
  • Entities' layer can be changed through Entity.dxf.layer

07/02/2019 (Tue)

• Continue the dxf processing
• Following tasks can be completed by running the code:
  • Able to detect pin center coordinate
  • Able to draw arbitrary shape around the pin center
  •