MCU

6dofPCB — Virtual Flux (Product Requirements & Overview)

1. Product Vision

Virtual Flux is a high-fidelity, hardware-in-the-loop soldering simulator. It bridges physical motion and virtual physics to create a realistic training and evaluation environment for hand soldering. By using a physical 6DOF (Six Degrees of Freedom) robotic arm that acts as the soldering iron (currently in development, with full keyboard/mouse fallbacks available now), users can practice their technique on a virtual PCB rendered in a Unity desktop application. The simulation provides deterministic, physics-based reactions—including thermodynamics, flux activation, and solder wetting—coupled with real-time evaluation.

2. Target Audience & Use Cases

• Soldering Trainees & Students: Learn proper technique (angle, dwell time, temperature control, flux application) without consuming physical consumables or risking damage to expensive boards.
• Instructors & Evaluators: Provide standardized, objective, and deterministic grading of a student's soldering joints.
• Hardware Enthusiasts: Experiment with a novel hardware-software interface.

3. Core Features & Requirements (V1)

3.1 Physics & Simulation Engine

The core of Virtual Flux is its deterministic, grid-based simulation running at a fixed 5 ms timestep in Unity.

• Thermal Model: Heuristic exponential heat transfer from the iron tip to the pad, propagating across a grid.
• Flux Dynamics: Tracks states of flux (Cold -> Active -> Burnt) based on temperature thresholds. Flux cleans oxidation and enables solder flow.
• Solder Flow & Wetting: Grid-based solder deposition that flows to heated cells. Features visual metallic rendering and dynamic fillet capillary action morphing towards component pins.
• Component Bonding: Solderable pins detect solid vs. molten solder. A wetting reflow state machine ensures pins only bond if they contact molten solder that subsequently cools and solidifies.

3.2 User Interaction & Tooling

While the physical arm is the primary input, V1 supports full keyboard/mouse fallbacks.

• 6DOF Iron: Translates and rotates in 3D space. Reports tip temperature and spatial pose.
• Toolbelt:
  • Solder Wire: Click-to-feed solder deposition.
  • Flux Pen / Paste: Apply flux to pads prior to heating.
  • Tweezers: Drag-and-drop SMD component placement (e.g., resistors) with snap-to-surface raycasting and kinematic stability.

3.3 Evaluation & HUD

• Real-Time Guidance: Dynamic UI panel tracking the active pad. Displays a collapsing step-by-step checklist (placement, flux, heat, solder, cool).
• Deterministic Scoring: Evaluates the joint based on strict tolerances:
  • Soldering angle (e.g., 40–55°)
  • Dwell time (e.g., 1.5–3 s)
  • Peak temperature (e.g., 250–360 °C)
  • Flux sequence (must flux before heating)
  • Solder volume and tip-feeding requirements.
• Status & Latency: Heads-up displays for iron temperature, active tool, board security status, and simulation frame timing.

4. System Architecture

The project is split into three tightly coupled domains:

4.1 Hardware (KiCad)

The physical 6DOF arm is driven by custom PCBs.

• MCU Board: The brains of the arm.
• Controller Board: Interfacing and power.
• Located in Hardware/ as KiCad 7+ projects and RS-274X Gerbers.

4.2 Firmware (C/C++)

• PlatformIO Project: Runs on the MCU board. Solves arm kinematics and streams the tool tip's pose and temperature over USB-serial to the PC.
• Located in Firmware/6DoF Firmware/ (currently in progress).
• Protocol locked and documented in docs/serial-protocol.md.

4.3 Software (Unity)

• Unity 6 LTS (6000.0.x) using the Universal Render Pipeline (URP) and the New Input System.
• Receives serial pose data (P,x,y,z,pitch,yaw,roll,temp,seq) and applies it to the virtual iron.
• Parses real Gerber files to generate the virtual copper PCB meshes.
• Located in Software/.

5. Repository Layout

6. Quick Start

1. Hardware: Open Hardware/MCU/MCU.kicad_pro or Hardware/Controller/Controller.kicad_pro in KiCad 7+.
2. Software: Open Software/ in Unity 6 LTS. Load Assets/Scenes/Workbench.unity and press Play. See Software/README.md for detailed keyboard/mouse controls.

7. Future Roadmap (Post-V1)

• Arm Firmware Completion: Finish the C/C++ kinematics solver and hardware integration.
• AI Joint-Quality Evaluation: Machine learning models to assess the visual quality of the final solder fillet.
• Advanced Hardware: Haptic feedback, VR integration, and BLE wireless connectivity.

License

TBD.