Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Collision Recovery Control of a Foldable Quadrotor

Karishma Patnaik, Shatadal Mishra, Zachary Chase, Wenlong Zhang

TL;DR

The paper tackles collision resilience for small UAVs by introducing a foldable quadrotor with integrated torsional springs that prolong impact duration and reduce peak forces on the main body. It combines a physics-based post-collision model with an adaptive recovery controller that generates a collision-driven setpoint from the observed impact velocity, enabling stable, overshoot-free reentry. Through simulations and real-time flight tests, the foldable design shows significantly lower rebound velocities and reliable recovery compared to a rigid quadrotor, improving survivability and mission continuity in cluttered environments. The results highlight a practical approach to collision resilience that preserves payload integrity and enables safer operation in high-disturbance scenarios.

Abstract

Autonomous missions of small unmanned aerial vehicles (UAVs) are prone to collisions owing to environmental disturbances and localization errors. Consequently, a UAV that can endure collisions and perform recovery control in critical aerial missions is desirable to prevent loss of the vehicle and/or payload. We address this problem by proposing a novel foldable quadrotor system which can sustain collisions and recover safely. The quadrotor is designed with integrated mechanical compliance using a torsional spring such that the impact time is increased and the net impact force on the main body is decreased. The post-collision dynamics is analysed and a recovery controller is proposed which stabilizes the system to a hovering location without additional collisions. Flight test results on the proposed and a conventional quadrotor demonstrate that for the former, integrated spring-damper characteristics reduce the rebound velocity and lead to simple recovery control algorithms in the event of unintended collisions as compared to a rigid quadrotor of the same dimension.

Collision Recovery Control of a Foldable Quadrotor

TL;DR

The paper tackles collision resilience for small UAVs by introducing a foldable quadrotor with integrated torsional springs that prolong impact duration and reduce peak forces on the main body. It combines a physics-based post-collision model with an adaptive recovery controller that generates a collision-driven setpoint from the observed impact velocity, enabling stable, overshoot-free reentry. Through simulations and real-time flight tests, the foldable design shows significantly lower rebound velocities and reliable recovery compared to a rigid quadrotor, improving survivability and mission continuity in cluttered environments. The results highlight a practical approach to collision resilience that preserves payload integrity and enables safer operation in high-disturbance scenarios.

Abstract

Autonomous missions of small unmanned aerial vehicles (UAVs) are prone to collisions owing to environmental disturbances and localization errors. Consequently, a UAV that can endure collisions and perform recovery control in critical aerial missions is desirable to prevent loss of the vehicle and/or payload. We address this problem by proposing a novel foldable quadrotor system which can sustain collisions and recover safely. The quadrotor is designed with integrated mechanical compliance using a torsional spring such that the impact time is increased and the net impact force on the main body is decreased. The post-collision dynamics is analysed and a recovery controller is proposed which stabilizes the system to a hovering location without additional collisions. Flight test results on the proposed and a conventional quadrotor demonstrate that for the former, integrated spring-damper characteristics reduce the rebound velocity and lead to simple recovery control algorithms in the event of unintended collisions as compared to a rigid quadrotor of the same dimension.

Paper Structure

This paper contains 14 sections, 6 equations, 9 figures, 1 table.

Table of Contents

  1. Introduction
  2. Hardware
  3. Finite Element Analysis
  4. Analysis And Control
  5. Quadrotor Modeling
  6. Analyzing Post-Collision Dynamics
  7. Initial Conditions Post Collision
  8. Comparison with Rigid Quadrotor
  9. Proposed Recovery Controller
  10. Simulations and Experimental Validation
  11. Real-Time Flight Tests
  12. Hardware Setup
  13. Experimental Results
  14. Conclusion and Future Work

Figures (9)

  • Figure 1: The foldable quadrotor proposed in this paper. The left figure shows the top view and the right figure shows the side view of the quadrotor. A video for the experiments can be found at https://youtu.be/obepryCvdZ4
  • Figure 2: Exploded view of the components of the folding mechanism based on a passive spring
  • Figure 3: A top view of the quadrotor dimensions after complete retraction during collision. Besides being collision resilient, the fully extended arms have a motor-motor distance of about 290mm and the completely retracted position is around 230mm, a 20% reduction in the motor-motor distance.
  • Figure 4: Cross section cut of the arm geometry and factor of safety plot denoting impact force intensity.
  • Figure 5: Inertial and body frame description. The quadrotor arms are modelled as spring integrated subsystems with the same spring constant for every arm.
  • ...and 4 more figures