Designed a robust control system for quadrotors to safely land after complete failure of one motor. Achieved stable descent by abandoning yaw control and using a custom PID-based architecture, validated through high-fidelity simulation with 97.5% failure detection accuracy.
Emergency Landing and Positional Control for Quadrotor with Motor Failure
Introduction
Emergency Landing and Positional Control System for Quadrotor with Motor Failure As part of Team 97 at the Inter IIT Tech Meet 13.0 – Ideaforge Challenge, we developed an innovative emergency landing system for quadrotor drones facing complete failure of a motor. Recognizing that yaw control becomes infeasible after such a failure, we designed a novel control architecture that intentionally abandons yaw regulation and focuses on modulated thrust and pitch to achieve a controlled descent. We implemented a digital signal filtering system that accurately detects the failed motor with 97.5% precision using band-pass filtering and thresholding. Upon failure detection, the drone’s body frame is rotated by ±45° or ±135° based on the failed rotor, allowing the remaining motors to maintain pitch and thrust symmetry. The control system comprises a custom cascade of PID controllers for thrust and pitch, a control allocator, and a normalization layer. Our simulation in PX4 + Gazebo showed the drone could descend in 4.6 seconds—1.8× slower than free fall—indicating effective control. The system was tested on a 0.7 kg quadrotor and is scalable to 2.0 kg platforms, with future potential for post-failure hover and limited navigation. This project highlights critical thinking in real-world UAV failure recovery, with strong emphasis on embedded systems, control design, and simulation-based validation.