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Scratch Team of Single-Rotor Robots and Decentralized Cooperative Transportation with Robot Failure

Koshi Oishi, Yasushi Amano, Jimbo Tomohiko

TL;DR

This work addresses robust cooperative transport using a heterogeneous team of single-rotor aerial robots. It proposes a decentralized control framework combining a Robust Feedback Controller (RFC) that enforces strictly positive realness under mass/COM fluctuations and robot failures with a Variable-Gain Autonomous Switching Controller (VG-ASSC) for multi-output error stabilization, plus an output-approximation scheme to decouple inputs. The method is validated through simulations with different payload shapes and robot mixes, and via real-world experiments showing resilience to COM shifts and failures while maintaining performance. The results demonstrate plug-in/plug-out adaptability and improved robustness over traditional PID approaches, highlighting practical potential for reuse and scalable, heterogeneous aerial transportation.

Abstract

Achieving cooperative transportation by aerial robot teams ensures flexibility regarding payloads and robustness against failures, which has garnered significant attention in recent years. This study proposes a flexible decentralized controller for robots and the shapes of payloads in a cooperative transport task using multiple single-rotor robots. The proposed controller is robust to mass and center of mass (COM) fluctuations and robot failures. Moreover, it possesses asymptotic stability against dynamics errors. Additionally, the controller supports heterogeneous single-rotor robots. Thus, robots with different specifications and deterioration may be effectively utilized for cooperative transportation. This performance is particularly effective for robot reuse. To achieve the aforementioned performance, the controller consists of a parallel structure comprising two controllers: a feedback controller, which renders the system strictly positive real, and a nonlinear controller, which renders the object asymptotic to the target. First, we confirm cooperative transportation using 8 and 10 robots for two shapes through numerical simulation. Subsequently, the cooperative transportation of a rectangle payload (with a weight of approximately 3 kg and maximum length of 1.6 m) is demonstrated using a robot team consisting of three types of robots, even under robot failure and fluctuation in the COM.

Scratch Team of Single-Rotor Robots and Decentralized Cooperative Transportation with Robot Failure

TL;DR

This work addresses robust cooperative transport using a heterogeneous team of single-rotor aerial robots. It proposes a decentralized control framework combining a Robust Feedback Controller (RFC) that enforces strictly positive realness under mass/COM fluctuations and robot failures with a Variable-Gain Autonomous Switching Controller (VG-ASSC) for multi-output error stabilization, plus an output-approximation scheme to decouple inputs. The method is validated through simulations with different payload shapes and robot mixes, and via real-world experiments showing resilience to COM shifts and failures while maintaining performance. The results demonstrate plug-in/plug-out adaptability and improved robustness over traditional PID approaches, highlighting practical potential for reuse and scalable, heterogeneous aerial transportation.

Abstract

Achieving cooperative transportation by aerial robot teams ensures flexibility regarding payloads and robustness against failures, which has garnered significant attention in recent years. This study proposes a flexible decentralized controller for robots and the shapes of payloads in a cooperative transport task using multiple single-rotor robots. The proposed controller is robust to mass and center of mass (COM) fluctuations and robot failures. Moreover, it possesses asymptotic stability against dynamics errors. Additionally, the controller supports heterogeneous single-rotor robots. Thus, robots with different specifications and deterioration may be effectively utilized for cooperative transportation. This performance is particularly effective for robot reuse. To achieve the aforementioned performance, the controller consists of a parallel structure comprising two controllers: a feedback controller, which renders the system strictly positive real, and a nonlinear controller, which renders the object asymptotic to the target. First, we confirm cooperative transportation using 8 and 10 robots for two shapes through numerical simulation. Subsequently, the cooperative transportation of a rectangle payload (with a weight of approximately 3 kg and maximum length of 1.6 m) is demonstrated using a robot team consisting of three types of robots, even under robot failure and fluctuation in the COM.
Paper Structure (25 sections, 1 theorem, 45 equations, 17 figures, 5 tables)

This paper contains 25 sections, 1 theorem, 45 equations, 17 figures, 5 tables.

Table of Contents

  1. Introduction
  2. Related work
  3. Flight model
  4. Decentralized control
  5. Error system
  6. Input transformation
  7. Error dynamics
  8. Output transformation
  9. Robust feedback controller (RFC)
  10. Uncertainty sharing
  11. Strictly positive realization
  12. VG-ASSC for multiple output systems
  13. Asymptotically stabilization
  14. Output approximation
  15. Numerical simulation
  16. ...and 10 more sections

Key Result

Theorem 4.1

Applying the controller of eq. (eq:assc) to the error system comprising eq. (eq:st_fin) shows that the error $\bm{\eta}$ satisfies $\bm{\eta} \rightarrow 0$ as $t \rightarrow \infty$.

Figures (17)

  • Figure 1: Concept
  • Figure 2: Model of cooperative transportation using heterogeneous single-rotor robots ($n_1 = 4$, $n_2 = 2$, $n_3 = 1$, $n_2 = 2$)
  • Figure 3: Fluctuations
  • Figure 4: Pole assignment
  • Figure 5: Proposed controller
  • ...and 12 more figures

Theorems & Definitions (1)

  • Theorem 4.1