In this paper, a nonlinear model of the underactuated six degrees of freedom (6 DOF) quadrotor helicopter was derived based on the Newton-Euler formalism. A new nonlinear robust control strategy was proposed to solve the stabilizing and path following problems in presence of external disturbances and parametric uncertainties. The proposed control structure consist of a sliding mode control base...

In this paper the Wheeled Acrobot (WAcrobot), a novel mechanical system consisting of an underactuated double inverted pendulum robot (Acrobot) equipped with actuated wheels, is described. This underactuated and highly nonlinear system has potential applications in mobile manipulators and leg-wheeled robots. It is also a testbed for researchers studying advanced methodologies in nonlinear contr...

In this work an efficient dynamics algorithm is developed which is applicable to a wide range of multibody systems, including underactuated systems, branched or treetopology systems, robots, and walking machines. The dynamics algorithm is differentiated with respect to the input parameters in order to form sensitivity equations. The algorithm makes use of techniques and notation from the theory...

A nonlinear, closed-loop, time-invariant controller that globally stabilizes an underactuated marine vehicle on a straight course is proposed. Traditional surface vessel linear course tracking autopilots are designed applying linear control methods on the linearized model, thus yielding only local results. Indeed due to the underactuated nature of the system, the model cannot be feedback linear...

This paper presents new techniques for controlling the motion of an underactuated vehicle when disturbances are present and only imperfect state measurements are available for feedback. A state feedback controller is developed and then it is converted to an imperfect state measurement feedback controller. The state feedback tracking control law uses an H∞-optimal design and produces a locally e...

Differential flatness is a property which substantially reduces the difficulty involved in generating dynamically feasible trajectories for underactuated robotic systems. However, there is a large class of robotic systems that are not differentially flat, and an efficient method for computing dynamically feasible trajectories does not exist. In this paper we introduce a weaker but more general ...

We propose a constructive control design for stabilization of non-periodic trajectories of underactuated robots. An important example of such a system is an underactuated “dynamic walking” biped robot traversing rough or uneven terrain. The stabilization problem is inherently challenging due to the nonlinearity, open-loop instability, hybrid (impact) dynamics, and target motions which are not k...

Switched control synthesis is developed for underactuated mechanical systems. In order to locally stabilize an underactuated system around an unstable equilibrium, its output is specified in such a way that the corresponding zero dynamics is locally asymptotically stable. Once such an output has been chosen, the desired stability property of the closed-loop system is provided by applying a Zeno...

This paper presents an adaptive fuzzy backstepping control method that incorporates the dynamic equilibrium state (DES) theory to carry out path tracking for underactuated ships in presence of parameter variations and external disturbances induced by wind, wave and current. First, the optimal DES reference trajectories are designed for the sway displacement and the yaw angle. Then, by combining...

Recently, passivity based control theory (energy approaches) has undergone a breakthrough in dealing with underactated mechanical systems with two successful and similar tools, controlled Lagrangians and controlled Hamiltanians (IDAPBC). Because of the complexity, successful case studies are lacking, for example, MIMO, underactuated and unstable systems. The seminal paper of controlled Lagrangi...