SAFE-ROVER — Failsafe Carrier Board & Power Distribution

High-reliability carrier board and power distribution architecture designed for the SAFE-ROVER 6WD Autonomous Unmanned Ground Vehicle (UGV) competing in TEKNOFEST 2026.

Engineered in KiCad with a strict 5-layer failsafe architecture, complete galvanic isolation between high-current drive lines and sensitive compute logic, and an independent hardware watchdog subsystem capable of mechanically arresting the vehicle on a 45% slope within 0.1 seconds.

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Core Engineering Principles

1. Galvanic & Optical Isolation: High-current 22.2V motor drive rails (drawing up to 120A peak) are electrically and physically isolated from 3.3V / 5V compute lines using high-speed optocouplers and dedicated relay banks to eliminate electromagnetic interference (EMI).
2. Deterministic Hardware Failsafe: Autonomous software (ROS 2 / Jetson) can fail or crash. If the software heartbeat ceases or a remote LoRa emergency stop signal arrives, an independent hardware supervisor microcontroller immediately arrests the vehicle with zero software dependency.
3. Distributed Control Architecture: Offloads hard real-time PWM generation, current sensing, and safety interlocks to dual microcontrollers, shielding the primary NVIDIA Jetson Orin Nano compute module from noise and pin contention.

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System Architecture (5-Tier Design)

[4x 6S LiPo 24Ah] ──> [100A BMS + ANL Fuse] ──> [High-Current Contactor] ──> [120A Power Busbar]
                                                         │                          │
                                             [E-Stop / K5 Relay]            [6x BTS7960 43A]
                                                         │                          │
                                                [Failsafe Trigger]          [6WD DC Motors +
                                                         ▲                   6x NC EM Brakes]
                                                         │
   [NVIDIA Jetson Orin Nano] ──(UART / Heartbeat)──> [ESP32-C3 Watchdog] <──(SPI)── [LoRa 915MHz]
   [ROS 2 / SLAM / YOLOv8  ] ──(PWM / Actuation)───> [ESP32 Primary MCU]

1. Power Distribution (Module 1)

• Battery Pack: 4x 6S (22.2V) 6000mAh modular LiPo pack connected in parallel (24Ah total capacity). Eliminates single-cell failure vulnerability and optimizes weight distribution across the 6WD chassis.
• Protection & Switching: Daly 100A BMS with individual cell balancing. System protection via 80A/100A ANL fuse, mushroom-head NC mechanical E-Stop button, and a high-current DC contactor.
• Buck Regulation: High-efficiency DC-DC step-down converters providing clean, decoupled 12V and 5V rails for sensor and compute payloads.

2. Compute, Logic & Safety MCU (Module 2)

• High-Level Compute: NVIDIA Jetson Orin Nano running ROS 2 Jazzy, Real-Time SLAM, YOLOv8 object detection, and path planning.
• Low-Level RTOS Controller: ESP32 Dev Module converting Jetson velocity commands into high-frequency PWM motor signals and managing auxiliary payload telemetry.
• Independent Watchdog Supervisor: ESP32-C3 dedicated solely to safety. Continuously monitors the Jetson "Heartbeat" signal. If communication drops or a remote E-Stop is triggered, the K5 safety relay instantly de-energizes the contactor.

3. Mobility & Drive Actuation (Module 3)

• Motor Drivers: 6x BTS7960 43A H-Bridge drivers powered directly from the 22.2V high-current busbar with analog current feedback sensing.
• Actuation: 6x high-torque geared DC drive motors operating in a 6-wheel differential drive configuration.
• Electromagnetic Fail-Safe Brakes: 6x Normally Closed (NC) electromagnetic shaft brakes. Energized (12V) to release; upon any power loss or emergency trigger, mechanical spring force clamps all six wheel shafts in under 100 milliseconds, securing the rover on steep inclines up to 45%.

4. Telemetry & Remote Safety (Module 4 & 5)

• RF Link: Long-range LoRa 915 MHz transceiver over SPI for ground-station telemetry and out-of-band remote emergency killswitch signals.
• Sensor Payload: Interfaces for RPLidar A1M8 360° LIDAR, Intel RealSense D435i depth camera, BNO055 9-DOF absolute orientation IMU, and ultrasonic proximity arrays.

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Repository Structure

carrier_board/
├── carrier_board.kicad_pro    # KiCad 8 project file
├── carrier_board.kicad_sch    # Top-level hierarchical schematic sheet
├── carrier_board.kicad_pcb    # Multi-layer PCB layout and routing
├── sheets/                    # Hierarchical schematic modules
│   ├── power.kicad_sch        # High-current busbar, contactor & buck converters
│   ├── mcu.kicad_sch          # Jetson pinouts, ESP32, ESP32-C3 watchdog
│   ├── failsafe.kicad_sch     # K5 relay, optocouplers & NC brake firing circuit
│   ├── motors.kicad_sch       # 6x BTS7960 driver arrays and decoupling
│   ├── sense.kicad_sch        # Current shunt mux, voltage dividers & telemetry
│   └── interface.kicad_sch    # Sensor connectors, level-shifters & LoRa SPI
└── docs/
    ├── proje.md               # Full Turkish hardware engineering specification
    ├── preview.png            # Visual schematic preview
    └── BTS7960 Motor Driver.pdf

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Opening the Project

1. Install KiCad 7.0+ (recommended: KiCad 8.0+).
2. Clone this repository:

   git clone https://github.com/aToom13/kiCAD.git

3. Open carrier_board/carrier_board.kicad_pro in KiCad.
4. Open the root schematic carrier_board.kicad_sch to navigate the hierarchical sheets.

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Author

Akif Efe Konuksever (@aToom13)
Software Engineering @ University of New York Tirana
Autonomous Systems & Robotics Enthusiast