KICAD DESIGN

Table of Contents

• About
• Scope of This Submission
• Note on Physical Fabrication
• The Story Behind NEXUS-TN
• The Ecosystem: 3 Parts, 1 Station
• Part 1 — The Robotic Arm (3 Gripper Types)
• Part 2 — The Sorting Conveyor
• Part 3 — Transport Robot "SAMIR-KAHWEJI"
• Electronics & PCB
• 3D Printing — Materials & Settings
• Fasteners
• Repository Structure
• CAD Files
• Simulations
• On AI Assistance
• Future Improvements
• License

About

NEXUS-TN is a small industrial cell that picks up a product, inspects it, sorts it, and hands it off to a mobile transport robot — a mini factory line, fully open and 3D-printable.

1. Robotic Arm on a linear XX' axis, swappable gripper, RealSense vision.
2. Sorting Conveyor — inspects and rejects damaged items.
3. SAMIR-KAHWEJI — 6-to-4-wheel transport robot, delivers the product following a line.

Designed from scratch in SolidWorks and KiCad.

Scope of This Submission

Mechanical CAD + custom KiCad PCB for the arm/conveyor subsystem, plus the full mechanical design of SAMIR-KAHWEJI. Firmware is not included yet — control architecture is documented in 03_DOCS/wiring/.

Note on Physical Fabrication

I don't yet have access to a 3D printer, a RealSense camera, or a Raspberry Pi — import taxes make them very expensive in Tunisia, and local paid makerspaces are scarce. So NEXUS-TN ships as a complete, print-ready CAD + PCB package (STEP, STL, native source) rather than a photographed build. The renders and simulations show the mechanisms in motion instead.

The Story Behind NEXUS-TN

NEXUS-TN started as a single robotic arm. While building it, I asked myself: does this have a real purpose — could it teach something, could it fit an actual industrial process? That question turned the arm into a full chain: arm → conveyor → transport robot.

I also noticed most robotics kits only ever expose one gripper type, forcing anyone curious about a different mechanism to buy a whole new kit. So the arm here supports 3 interchangeable gripper types plus an open connector standard — to teach more, and cost less.

The Ecosystem: 3 Parts, 1 Station

The arm and conveyor share one ESP32. SAMIR-KAHWEJI runs its own ESP32, fed by a Raspberry Pi 5.

Part 1 — The Robotic Arm (3 Gripper Types)

The arm travels on an XX' leadscrew axis. An Intel RealSense camera feeds a PC (Thonny + OpenCV), which sends decisions to the ESP32, driving the arm's servos, the leadscrew stepper, and the conveyor. The PCB rides on the arm itself, routed to stay clear of its full range of motion.

Modular gripper system: Link 2 (arm → gripper) is split in two — a tapped piece that always stays on the arm, and a threaded piece specific to each gripper. Swap only the threaded piece to change grippers, or design your own.

Type 1 — "Bird's Beak" Jaws translate in a straight line instead of pivoting. Closed /\ · Open :/ \

Type 2 — 5-Finger "Octopus" Five independent fingers close around the product for better conformity on irregular shapes.

Type 3 — Classic Parallel 10-finger gripper driven by two pinions.

Each type has its own SolidWorks, STEP, and STL set — printable independently.

Part 2 — The Sorting Conveyor

Belt driven by a stepper motor, controlled by the arm's ESP32. A rack-and-pinion pusher at the conveyor's entrance ejects broken/torn products straight into a recycling bin before they travel further.

Part 3 — Transport Robot "SAMIR-KAHWEJI"

• 6-to-4 wheels: a servo lifts the 2 front (guide) wheels for driving; they drop back down to dock — (the "truck" prop in the CAD is just a placeholder)
• Vision: camera on a 2-DOF mount, line-following + product detection. Raspberry Pi 5 processes video, sends commands to the onboard ESP32.
• Docking: small arc trajectory, then reverses in on its 2 guide wheels, which also stabilize the robot at rest.
• 4 shock absorbers absorb the ride-height change when the front wheels lift/drop.
• Onboard gripper: a small rack-and-pinion, servo-driven clamp secures the product during transit.

Electronics & PCB

Custom KiCad PCB around an ESP32-WROOM-32, with 4 separate LiPo rails (common ground):

• 7V → arm servos
• 11.1V (3S) → DRV8825, driving both the conveyor motor and the XX' leadscrew stepper
• 3.7V (1S) → the ESP32

SAMIR-KAHWEJI needs no dedicated PCB — ESP32 + 4 IBT drivers + PWM servo board + an isolated Raspberry Pi 5 power bank, wired directly (see wiring-transport-robot-samir-kahweji.txt).

Full BOM: 03_DOCS/list of electronics.xlsx.

3D Printing — Materials & Settings

ABS for structural/high-stress parts, PLA for covers and lightweight parts.

Fasteners

Total: 70 screws.

Repository Structure

NEXUS-TN/
│
├── 01_3D/
│   ├── SOLIDWORKS PARTS/
│   │   ├── ROBOTIC_ARM(3 TYPES)/
│   │   │   ├── SOLIDWORKS PARTS/
│   │   │   │   ├── ROBOTICS_ARM TYPE 1/   # Arm Type 1
│   │   │   │   ├── ROBOTIC_ARM TYPE 2/    # Arm Type 2 + 5-finger gripper
│   │   │   │   └── ROBOTIC_ARM TYPE 3/    # Arm Type 3 + classic gripper
│   │   │   └── STEP FILES/
│   │   ├── CONVEYOR/
│   │   ├── TRANSPORT_ROBOT (SAMIR-KAHWEJI)/
│   │   └── main assembly conveyor_roboticarm_transportrobot.STEP
│   │
│   └── STL/
│       ├── ROBOTIC_ARM(3 TYPES)/
│       │   ├── STL ROBOTIC ARM 1/         # Arm Type 1
│       │   ├── STL ROBOTIC ARM 2/         # Arm Type 2
│       │   └── dossier tanthif 2/         # Arm Type 3
│       ├── CONVOYER/
│       └── TRANSPORT_ROBOT (SAMIR-KAHWEJI)/
│
├── 02_PCB_DESIGN/
│   ├── KICAD DESIGN.kicad_sch / .kicad_pcb / .kicad_pro / .kicad_prl

Folder names under ROBOTIC_ARM(3 TYPES) grew organically per gripper type (dossier tanthif 2, etc.) — each "TYPE" folder is self-contained and printable on its own. main assembly conveyor_roboticarm_transportrobot.STEP combines the whole ecosystem into one file.

CAD Files

Per subsystem: native SolidWorks source, STEP (any CAD tool), and STL (slicer-ready) — under 01_3D/.

Simulations

XX' axis travel

6-to-4 wheel transform The gap created in the drive wheels during the transformation is absorbed by the 4 shock absorbers.

SAMIR-KAHWEJI's onboard gripper

Future Improvements

• Physical build, once printing/camera/Pi are accessible
• Firmware: ESP32 control + OpenCV sorting pipeline
• Firmware: SAMIR-KAHWEJI line-following / docking loop
• An autonomous delivery truck with its own onboard mechanical system to take the product directly from SAMIR-KAHWEJI

License

MIT License.