# Drone Design

Currently the hardware or software of the drone does not exist, however preliminary ideas have been formulated. This should sereve as a good baseline for what the drone needs to include, how it communicated and what safety features it should include.

### Drone Subsystem Architecture

The drone is a custom-built, high-performance four rotor platform optimized for autonomous indoor navigation within a 10 x 10 x 4m netted flight cage. It features a decoupled, two-tier processing architecture: a dedicated Flight Controller (FC) handles real-time attitude estimation and low-level flight stability, while an onboard Companion Computer executes high-level vision processing, obstacle avoidance, and mission state machines.

### System Specifications

<table id="bkmrk-parameterspecificati" style="margin-bottom: 32px;"><colgroup><col></col><col></col><col></col></colgroup><tbody><tr><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">**Parameter**

</td><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">**Specification**

</td><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">**Engineering Note**

</td></tr><tr><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">**Total Mass**

</td><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">1.95 kg

</td><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">All-Up Weight (AUW) including 6S 4500mAh LiPo &amp; Jetson Nano.

</td></tr><tr><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">**Hover Power**

</td><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">380 W

</td><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">Average draw during steady hover, including onboard compute payload.

</td></tr><tr><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">**Max Power**

</td><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">920 W

</td><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">Peak current draw during emergency maneuvers / dynamic correction.

</td></tr><tr><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">**Power Source**

</td><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">6S 4500 mAh LiPo

</td><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">Sized to complete the 3-mission task cycle within the 30-min window.

</td></tr><tr><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">**Primary Link**

</td><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">5.8 GHz (Wi-Fi)

</td><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">IEEE 802.11 compliant link for high-throughput video &amp; telemetry.

</td></tr><tr><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">**Safety Link**

</td><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">2.4 GHz

</td><td style="border: 1px solid rgb(196, 199, 197); padding: 8px 12px;">Low-latency RadioMaster ExpressLRS manual safety link.

</td></tr></tbody></table>

### Hardware Integration &amp; Component Breakdown

The hardware selection prioritizes structural rigidity, vibration isolation, and indoor localization reliability without reliance on satellite positioning.

- **Carbon Fiber Frame:**<span style="white-space: pre-wrap;"> Built on a 7-inch carbon fiber racing frame selected for high torsional stiffness and ample top/bottom deck area to accommodate the companion computer, power distribution, and downward-facing optical sensors.</span>
- **Propulsion System:**<span style="white-space: pre-wrap;"> Driven by four 1350 Kv brushless motors paired with 7-inch dual-blade propellers. This combination balances high thrust-to-weight ratio with electrical efficiency during steady hovering.</span>
- **Enclosure &amp; Sensor Mounts:**<span style="white-space: pre-wrap;"> A custom 3D-printed housing protects sensitive core electronics from mechanical impacts and provides a rigid down-facing mount for the primary visual landing camera.</span>
- **Flight Control Stack:**<span style="white-space: pre-wrap;"> Uses a T-Motor Velox F7 SE Flight Controller combined with a V70A SE 4-in-1 ESC. The F7 FC is flashed with open-source PX4 or ArduPilot firmware to support MAVLink offboard commands.</span>
- **Indoor Positioning Sensors:**<span style="white-space: pre-wrap;"> Equipped with a Mateksys Optical Flow &amp; LiDAR sensor package. This provides real-time ground velocity tracking and precise altitude measurement to replace GPS in enclosed, signal-degraded environments.</span>
- **Companion Computer &amp; Vision Sensor:**<span style="white-space: pre-wrap;"> An onboard NVIDIA Jetson Nano processes high-level autonomy algorithms. It interfaces with a </span>**Global Shutter USB camera**<span style="white-space: pre-wrap;"> targeting ArUco markers.</span>

### Software &amp; Autonomy Architecture

<span style="white-space: pre-wrap;">The high-level autonomy suite is developed and executed within </span>**MATLAB/Simulink**.

- **Vision Processing Pipeline:**<span style="white-space: pre-wrap;"> A dedicated Simulink model performs real-time image processing in two stages:</span>
    1. **Target Probe Detection:**<span style="white-space: pre-wrap;"> Color-space thresholding (HSV) tuned specifically for yellow-green probe identification.</span>
    2. **Landing &amp; Alignment:**<span style="white-space: pre-wrap;"> ArUco tag identification libraries compute relative 3D pose vectors for accurate landing alignment.</span>
- **Telemetry &amp; Offboard Communications:**<span style="white-space: pre-wrap;"> High-level trajectory setpoints and real-time state estimates are streamed over MAVLink protocol via a 5.8 GHz Wi-Fi bridge.</span>

##### Design Rationale: Global Shutter vs. Rolling Shutter in Indoor Vision:

<span style="white-space: pre-wrap;"> Standard CMOS cameras use rolling shutters that expose pixels line-by-line. Under high drone vibration or swift pitch/roll maneuvers, this introduces severe image warping ("jello effect"), causing ArUco marker detection algorithms to fail or miscalculate target distance.</span>

<span style="white-space: pre-wrap;">Integrating a </span>**Global Shutter camera**<span style="white-space: pre-wrap;"> captures the entire sensor plane simultaneously. This eliminates rolling-shutter distortion during motion, ensuring solid target tracking and accurate 3D pose estimation even during aggressive flight corrections.</span>

### Safety &amp; Fail-Safe Architecture

To guarantee total flight control and satisfy safety protocols within the cage environment, the drone incorporates a triple-redundant fail-safe architecture.

- **Manual RC Override (Primary Safety):**<span style="white-space: pre-wrap;"> A dedicated physical switch assigned on the pilot’s RadioMaster Boxer transmitter immediately revokes offboard MATLAB control, returning raw flight control to the operator.</span>
- **Hard-Coded 3D Geofence (Boundary Protection):**<span style="white-space: pre-wrap;"> A cylindrical 3D geofence is defined directly inside the FC firmware, preventing the drone from drifting into the cage netting regardless of automated setpoint commands.</span>
- **GCS E-Stop (Ground Control Safety):**<span style="white-space: pre-wrap;"> The MATLAB/Simulink operator dashboard features an emergency software kill-switch that transmits an instant motor-disarm instruction.</span>

##### <span style="white-space: pre-wrap;">Signal Loss Procedure (Link-Loss Recovery): </span>

<span style="white-space: pre-wrap;">If the primary 5.8 GHz Wi-Fi data link or 2.4 GHz ExpressLRS control link experiences a complete disconnect, the F7 FC and T-Motor ESCs bypass state-estimation and execute an immediate, autonomous </span>**Land-In-Place**<span style="white-space: pre-wrap;"> sequence. The FC maintains attitude lock while decreasing throttle at a fixed, controlled descent rate to land vertically without drifting.</span>