robocon-r2-drum

R2 was the scoring robot — responsible for receiving balls from R1 and delivering them into scoring positions using a high-speed drum mechanism. Designed for reliability and speed: it had to execute its scoring sequence in under 5 seconds per cycle to keep up with R1's placement rate.

The drum delivery mechanism needed consistent ball trajectory regardless of ball surface wear or variation in loading angle from R1. Early prototypes had a 30% miss rate due to inconsistent drum RPM at load time. The inter-robot coordination also had to be failsafe — if R2 wasn't ready, R1 had to hold without disrupting its own task queue.

Designed all PCBs for R2: power distribution board, BLDC driver board for the drum motor, and the main STM32 controller board. Implemented the drum speed controller with a closed-loop RPM hold using hall-effect feedback. Built the inter-robot comms protocol — a lightweight UART handshake running at 115200 baud with CRC8 error detection.

R2 achieved a >95% delivery success rate in practice runs. The inter-robot protocol had zero communication failures across all scrimmage and competition matches. Drum mechanism produced consistent ball trajectory ±2° across 500+ cycles.