scholarly journals Stabilization of a Rigid Body Payload With Multiple Cooperative Quadrotors

Author(s):  
Farhad A. Goodarzi ◽  
Taeyoung Lee

Abstract This paper presents the full dynamics and control of arbitrary number of quadrotor unmanned aerial vehicles (UAVs) transporting a rigid body. The rigid body is connected to the quadrotors via flexible cables where each flexible cable is modeled as a system of arbitrary number of serially connected links. It is shown that a coordinate-free form of equations of motion can be derived for the complete model without any simplicity assumptions that commonly appear in other literature, according to Lagrangian mechanics on a manifold. A geometric nonlinear controller is presented to transport the rigid body to a fixed desired position while aligning all of the links along the vertical direction. A rigorous mathematical stability proof is given and the desirable features of the proposed controller are illustrated by numerical examples and experimental results.

Author(s):  
Firdaus E. Udwadia ◽  
Aaron D. Schutte

This paper develops a unified methodology for obtaining both the general equations of motion describing the rotational dynamics of a rigid body using quaternions as well as its control. This is achieved in a simple systematic manner using the so-called fundamental equation of constrained motion that permits both the dynamics and the control to be placed within a common framework. It is shown that a first application of this equation yields, in closed form, the equations of rotational dynamics, whereas a second application of the self-same equation yields two new methods for explicitly determining, in closed form, the nonlinear control torque needed to change the orientation of a rigid body. The stability of the controllers developed is analysed, and numerical examples showing the ease and efficacy of the unified methodology are provided.


2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Peng Xu ◽  
Richard E. Groff ◽  
Timothy Burg

The classic tabletop game Shoot-the-Moon has interesting dynamics despite its simple structure, consisting of a steel ball rolling on two cylindrical rods. In this paper, we derive the equations of motion for Shoot-the-Moon using a Lagrangian approach and examine the underactuated, nonlinear, and nonholonomic dynamics. Two ball position controllers are designed, one using a local linearization and another using the nonlinear dynamics. Simulations of both controllers are performed, showing that the ball converges to the setpoint position for the linearized controller and continuous signals can be tracked by the nonlinear controller. Finally, the experimental results are presented for the nonlinear controller applied to a physical implementation of Shoot-the-Moon. The effect of the nonholonomic constraint relating the ball’s linear and angular position is demonstrated. This system has rich dynamics that can provide a challenging problem for control design and serve as a new educational example.


Author(s):  
Andreas Müller ◽  
Shivesh Kumar

AbstractDerivatives of equations of motion (EOM) describing the dynamics of rigid body systems are becoming increasingly relevant for the robotics community and find many applications in design and control of robotic systems. Controlling robots, and multibody systems comprising elastic components in particular, not only requires smooth trajectories but also the time derivatives of the control forces/torques, hence of the EOM. This paper presents the time derivatives of the EOM in closed form up to second-order as an alternative formulation to the existing recursive algorithms for this purpose, which provides a direct insight into the structure of the derivatives. The Lie group formulation for rigid body systems is used giving rise to very compact and easily parameterized equations.


2014 ◽  
Vol 33 (3) ◽  
pp. 315-332 ◽  
Author(s):  
Xiao-Feng Liu ◽  
Hai-Quan Li ◽  
Yi-Jun Chen ◽  
Guo-Ping Cai ◽  
Xi Wang

1992 ◽  
Vol 114 (1) ◽  
pp. 41-49 ◽  
Author(s):  
K. W. Buffinton

The purpose of this investigation is to study the formulation of equations of motion for flexible robots containing translationally moving elastic members that traverse a finite number of distinct support points. The specific system investigated is a two-degree-of-freedom manipulator whose configuration is similar to that of the Stanford Arm and whose translational member is regarded as an elastic beam. Equations of motion are formulated by treating the beam’s supports as kinematical constraints imposed on an unrestrained beam, by discretizing the beam by means of the assumed modes technique, and by applying an alternative form of Kane’s method which is particularly well suited for systems subject to constraints. The resulting equations are programmed and are used to simulate the system’s response when it performs tracking maneuvers. The results provide insights into some of the issues and problems involved in the dynamics and control of manipulators containing highly elastic members connected by prismatic joints.


Author(s):  
L. D. Akulenko ◽  
D. D. Leshchenko ◽  
T. A. Kozachenko

Perturbed rotations of a rigid body close to the regular precession in the Lagrangian case under the action of a restoring moment depending on slow time and nutation angle, as well as a perturbing moment slowly varying with time, are studied. The body is assumed to spin rapidly, and the restoring and perturbing moments are assumed to be small with a certain hierarchy of smallness of the components. A first approximation averaged system of equations of motion for an essentially nonlinear two-frequency system is obtained in the nonresonance case. Examples of motion of a body under the action of particular restoring, perturbing, and control moments of force are considered.


Author(s):  
Yuan Cheng ◽  
Qian Zhou ◽  
Ge-Xue Ren ◽  
Hui Zhang

This paper studies the six degree-of-freedom active isolation of flexible supporting structures using Gough-Stewart platform. The problem arises from a large radio telescope in which the astronomical equipment is mounted on a platform to be stabilized, while the base platform of the mechanism itself is carried by a cable car moving along flexible cables. In this paper, the stabilization problem is equivalent to a dynamics and control problem of multi-body system. A control law of the prediction of the base platform and PD feedback is proposed for the six actuators of the Gough-Stewart platform. Based on numerical results, a model experimental setup has been built up. The control effects are measured with LTD 500 Laser Tracker.


2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Yong-Lin Kuo

This paper presents the nonlinear dynamic modeling and control of a tethered satellite system (TSS), and the control strategy is based on the state-dependent Riccati equation (SDRE). The TSS is modeled by a two-piece dumbbell model, which leads to a set of five nonlinear coupled ordinary differential equations. Two sets of equations of motion are proposed, which are based on the first satellite and the mass center of the TSS. There are two reasons to formulate the two sets of equations. One is to facilitate their mutual comparison due to the complex formulations. The other is to provide them for different application situations. Based on the proposed models, the nonlinear dynamic analysis is performed by numerical simulations. Besides, to reduce the convergence time of the librations of the TSS, the SDRE control with a prescribed degree of stability is developed, and the illustrative examples validate the proposed approach.


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