For a class of robot arms, a proportional derivative (PD) controller plus gravity compensation yields the global asymptotic stability for regulation tasks, and some proportional-integral-derivative (PID) controllers guarantee local regulation without gravity cancellation. However, these controllers cannot render asymptotic stability for tracking tasks. In this paper, a simple decentralized cont...

The aim of this study was to develop a more sophisticated model of the spleen tissue and investigate its interactions with a three-fingered laparoscopic grasper. The spleen tissue, modeled as a hyper viscoelastic material, was subjected to external loadings, imposed by rigid grasping jaws. The tissue deformation as well as the sliding occurrence between tissue and jaws was investigated using no...

A formal impulse-based analysis is presented for the collision of two rigid bodies at single contact point under Coulomb friction in three dimensions (3D). The tangential impulse at the contact is known to be linear in the sliding velocity whose trajectory, parametrized with the normal impulse and referred to as the hodograph, is governed by a generally non-integrable ordinary differential equa...

The key function of the teleoperation system is to support the operator to perform complex, uncertain tasks in hazardous and less structured environments, such as space, nuclear plants, battlefield, surveillance, and underwater operations. In this study a teleoperation system was designed by force feedback joystick, sliding mode non-linear controller and 2 degree of freedom revolute joint robot...

Rigid-tube computations of simple (transverse) shear in crystalline nanotube ropes (CNTRs) reveal that shear modulus and strength increase and decrease with the tube radius, respectively. High modulus to strength ratios suggest that dislocations play a minor role during their plasticity. The computed shear moduli are in agreement with previous studies, although shape change and rolling-based sh...

This study presents a sliding-mode neural-network (SMNN) control system for the tracking control of an n rigid-link robot manipulator to achieve high-precision position control. The aim of this study is to overcome some of the shortcomings of conventional robust controllers such as a model-based adaptive controller requires the system dynamics in detail; the fuzzy rule learning scheme has a lat...

This paper investigates the attitude tracking problem for rigid spacecraft. An adaptive backstepping sliding mode control law is proposed to solve this problem in the presence of inertia uncertainties and external disturbances. The control scheme is developed by combining sliding mode control with adaptive backstepping technique to achieve fast and accurate tracking responses. The proposed cont...

We study the connection between sliding friction and the phase behavior of a simple rigid bead-necklace model of a liquid crystal (LC) lubricant layer confined between two parallel plates. The dynamics is dependent on competing LC ordering mechanisms, including the direction of sliding, and an applied (electric) field. Together with temperature and an applied pressure, determining whether the l...

Distributed finite-time attitude containment control for multiple rigid bodies is addressed in this paper. When there exist multiple stationary leaders, we propose a model-independent control law to guarantee that the attitudes of the followers converge to the stationary convex hull formed by those of the leaders in finite time by using both the one-hop and two-hop neighbors’ information. We al...

The pleural space is modeled in two dimensions as a thin layer of fluid separating a deformable membrane and a rigid surface containing a bump. We computed the steady-state membrane configuration and fluid pressure distribution during relative sliding of the two surfaces. For physiologically relevant values of membrane tension, shear flow-induced pressures near the bump and far-field pressure g...