R6-7 Spy Bot

Inspiration

Rainbow Six Siege features a compact two-wheeled reconnaissance drone that operators deploy to scout enemy positions. We wanted to bring this gadget to life as a fully functional ground robot with live video streaming.

What it does

The R6-7 Spy Bot is a two-wheeled ground reconnaissance robot that allows an operator to remotely navigate tight spaces while viewing a live camera feed on a handheld controller.

Live FPV video streamed over 5.8 GHz analog to a portable display
Differential drive for agile maneuvering and zero-radius turns
Pitch-stabilized camera gimbal allowing the operator to look up/down
IMU-based stabilization that keeps the robot level during acceleration

The drone reaches speeds up to 14 mph.

How we built it

We designed a custom hardware architecture that prioritizes low latency and power stability.

Hardware:

Dual Raspberry Pi 4s (one on drone, one on controller)
MAXYNOS THOR brushless motors with 19:1 planetary gearboxes
50A bidirectional ESCs for forward/reverse control
MPU6050 IMU for pitch angle sensing
TS832/RC832 5.8 GHz analog FPV system
HV/LV System: 4S LiPo (14.8V) for motors, 18650 shield (5V) for compute

Software:

Multi-threaded C++ with three concurrent workers:
- Gamepad input at 200 Hz
- Motor control loop at 50 Hz with PID stabilization
- Camera streaming at 30 fps to framebuffer
Complementary filter fusing gyroscope and accelerometer data
Rate-limited throttle ramping to prevent tip-overs

Challenges we ran into

FPV antenna connection: Getting reliable video between the TS832 transmitter and RC832 receiver required careful positioning and testing different channels to avoid interference
nRF24L01+PA+LNA rx/tx: Receiving and transmitting packets between the controller and drone

Accomplishments that we're proud of

Managed to fit all hardware (two batteries, Pi, IMU, camera, servo gimbal, two motors, two ESCs, FPV transmitter) into a custom and compact chassis
Achieved sub-100ms video latency using analog FPV instead of WiFi streaming
Implemented smooth PID-based pitch stabilization that keeps the robot level during aggressive acceleration

What we learned

Multi-threading in C++: Using std::thread and std::atomic for lock-free communication between workers
PWM motor control: Servo-style 50 Hz PWM signals with 1000-2000μs pulse widths
Sensor fusion: Complementary filtering to combine gyro (fast, drifts) with accelerometer (slow, noisy)
PID tuning: Balancing Kp/Ki/Kd gains for responsive but stable control
Linux device interfaces: V4L2 for camera, /dev/input/js* for gamepad, /dev/fb0 for framebuffer

What's next for R6-7 Spy Bot

Better wheels and tires: We ran out of time to print the TPU-based tire
Jumping mechanism: The in-game drone can jump, looking to add a spring-loaded launcher
Autonomous features: Obstacle avoidance and waypoint navigation using computer vision