Proofs of Control of a Quadrotor and a Ground Vehicle Manipulating an Object

This paper focuses on the control of a cooperative system composed of an Unmanned Aerial Vehicle (UAV) and an Unmanned Ground Vehicle (UGV) manipulating an object. The two units are subject to input saturations and collaborate to move the object to a desired pose characterized by its position and inclination. The dynamics are derived using Euler-Lagrange method. A pre-stabilizing control law is proposed where the UGV is tasked to deploy the object to a certain position whereas the UAV adjusts its inclination. In particular, a proportional-derivative control law is proposed for the UGV, and a cascade control approach is used for the UAV, where the inner loop controls the attitude of the UAV and the outer loop stabilizes the inclination of the object. Then, we prove the stability of the points of equilibrium using small gain arguments. To ensure constraints satisfaction at all times, a reference governor unit is added to the pre-stabilizing control scheme. Finally, numerical results combined with experimental results are provided to validate the effectiveness of the proposed control scheme in practice.Comment: 16 pages, 7 figure

Wrench Capability Analysis of Aerial Cable Towed Systems

International audienceAerial cable towed systems (ACTSs) can be created by joining unmanned aerial vehicles (UAVs) to a payload to extend the capabilities of the system beyond those of an individual UAV. This paper describes a systematic method of evaluating the avail- able wrench set and the robustness of equilibrium of ACTSs by adapting wrench analysis techniques used in cable-driven parallel robots to account for the constraints of quadrotor actuation. Case studies are provided to demonstrate the analysis of different classes of ACTSs, as a means of evaluating the design and operating configurations

Extended Derivations and Additional Simulations for Aerial Robots Tethered by Cables or Bars

Online appendix to:``Dynamics, Control and Estimation for Aerial Robots Tethered by Cables or Bars'' IEEE Transaction on RoboticsThis document is a technical attachment to M. Tognon and A. Franchi ``Dynamics, Control and Estimation for Aerial Robots Tethered by Cables or Bars'' IEEE Transaction on Robotics as an extension of the differential flatness and simulation sections

Extended Derivations and Additional Simulations for Aerial Robots Tethered by Cables or Bars

Online appendix to:``Dynamics, Control and Estimation for Aerial Robots Tethered by Cables or Bars'' IEEE Transaction on RoboticsThis document is a technical attachment to M. Tognon and A. Franchi ``Dynamics, Control and Estimation for Aerial Robots Tethered by Cables or Bars'' IEEE Transaction on Robotics as an extension of the differential flatness and simulation sections

Dynamics, Control, and Estimation for Aerial Robots Tethered by Cables or Bars

Accepted for IEEE Transaction on RoboticsInternational audienceWe consider the problem of controlling an aerial robot connected to the ground by a passive cable or a passive rigid link. We provide a thorough characterization of this nonlinear dynamical robotic system in terms of fundamental properties such as differential flatness, controllability, and observability. We prove that the robotic system is differentially flat with respect to two output pairs: elevation of the link and attitude of the vehicle; elevation of the link and longitudinal link force (e.g., cable tension, or bar compression). We show the design of an almost globally convergent nonlinear observer of the full state that resorts only to an onboard accelerometer and a gyroscope. We also design two almost globally convergent nonlinear controllers to track any sufficiently smooth time-varying trajectory of the two output pairs. Finally we numerically test the robustness of the proposed method in several far-from-nominal conditions: nonlinear cross-coupling effects, parameter deviations, measurements noise and non ideal actuators