Abstract: This paper presents a nonlinear H∞ control law for underactuated mechanical systems with input coupling. Apart from the controlled degrees of freedom (DOF), the proposed controller considers the dynamics of the remaining DOF in the cost variable, which allows to stabilize them. The underactuated mechanical system is normalized to obtain a diagonal inertia matrix allowing to weigh with...

Path following of underactuated surface vessels is important practice in ship motion control field. Some of current studies have restrictions on forms of desired trajectory of which straight line or sinusoid curve was excluded. In this paper, adaptive robust controllers for path following of underactuated surface vessels are proposed based on hierarchical sliding mode method which suits various...

Smaller autonomous underwater vehicles that use differential thrust for surge and yaw motion control has the advantage of low cost and, at the same time, increased ma­ neuverability in yaw direction. However, since such vehicles are underactuated vehicles, design of an autonomous control system that enables the vehicle to autonomously track a predefined trajectory is challenging. In this paper,...

In this work, we attempt to learn a neural network policy for dynamic, underactuated locomotion tasks. Learning a policy for such a task is non trivial due to the dynamic, fast changing, non linear and contact rich dynamics of this task. We use existing trajectory optimization techniques to optimize a set of policies. For this, we present a method that allows to learn contact rich dynamics for ...

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...

In the development of robotic hands, researchers have sought to increase inherent functionality without incurring greater complexity and cost. In this paper, we extend the manipulation capabilities of a simple gripper through a novel, underactuated design that produces several distinctive modes of operation. The proposed asymmetric hand design, the Multi-Modal (M) Gripper, consists of a modular...

Second order sliding mode control synthesis is developed for underactuated mechanical systems, operating under uncertainty conditions. In order to locally stabilize an underactuated system around an unstable equilibrium, an output is specified in such a way that the corresponding zero dynamics is locally asymptotically stable. Then, the desired stability property of the closed-loop system is pr...

In the development of robotic hands, researchers have sought to increase inherent functionality without incurring greater complexity and cost. In this paper, we extend the manipulation capabilities of a simple gripper through a novel, underactuated design that produces several distinctive modes of operation. The proposed asymmetric hand design, the Multi-Modal (M 2 ) Gripper, consists of a modu...

This paper describes a new concept in underactuated hand design, motivated by a study of parallel mechanisms. Inspired by the end-effector motion and system reconfiguration in parallel wrists, we propose a morphology of fingers such that during fingertip precision manipulation the instantaneous screw axes, which describe the displacement of the grasped object respect to the palm of the hand, al...

Underactuated vehicles have gained much attention in the recent years due to increasing amount of aerial and underwater as well nanosatellites. Trajectory tracking control these is a substantial aspect for an range application domains. However, external disturbances parts internal dynamics are often unknown or very time-consuming model. To overcome this issue, we present law underactuated rigid...