Generalized ACE Constrained Progressive Edge-Growth LDPC Code Design

In this letter, we propose a generalization of the progressive edge-growth (PEG) algorithm with the aim of designing LDPC code graphs with substantially improved approximated cycle extrinsic message degree (ACE) properties. The proposed realization of generalized PEG algorithm outperforms original PEG algorithm and its subsequent modification proposed by Xiao and Banihashemi.     

Contact control concepts in manipulation robotics-an overview

This paper presents the state of the art in the control of robotic manipulators in constrained motion tasks. Contact control concepts are classified using different criteria, and their main characteristics are analyzed. For each of the presented contact control concepts, the essential characteristics are stated. The paper covers some early ideas and their later improvements, as well as trends in this field. The advantages and drawbacks of the various control schemes are outlined, and they are compared from the standpoint of their implementation issues. In the paper, all characteristic results in the stability analysis of robotic manipulators in the constrained motion tasks are briefly reported. A new approach to the correct solution of contact tasks control is mentioned as well     

Scalable Video Multicast Using Expanding Window Fountain Codes

Fountain codes were introduced as an efficient and universal forward error correction (FEC) solution for data multicast over lossy packet networks. They have recently been proposed for large scale multimedia content delivery in practical multimedia distribution systems. However, standard fountain codes, such as LT or Raptor codes, are not designed to meet unequal error protection (UEP) requirements typical in real-time scalable video multicast applications. In this paper, we propose recently introduced UEP expanding window fountain (EWF) codes as a flexible and efficient solution for real-time scalable video multicast. We demonstrate that the design flexibility and UEP performance make EWF codes ideally suited for this scenario, i.e., EWF codes offer a number of design parameters to be ldquotunedrdquo at the server side to meet the different reception criteria of heterogeneous receivers. The performance analysis using both analytical results and simulation experiments of H.264 scalable video coding (SVC) multicast to heterogeneous receiver classes confirms the flexibility and efficiency of the proposed EWF-based FEC solution.     

Human-and-Humanoid Postures Under External Disturbances: Modeling,Simulation, and Robustness. Part 2: Simulation and Robustness

The sophisticated method for mathematical modeling of humanoid robots formulated in Part 1 of this paper is applied here to the dynamic task of keeping a posture under disturbance, which is equally important to humans and humanoid robots. The idea of this work is to develop and realize a simulator tool for dynamic analysis of human-or-humanoid behavior under disturbances. To show the potentials and verify this tool, we comparatively analyze the robustness of some postures to external disturbance. At this stage of research we do not conduct real experiments with humans/humanoids but try to verify our simulation tool by relying on available experience. Therefore, the postures for comparison are taken from everyday life and from sports: upright standing, squat posture, and three karate postures. As the external disturbance we choose an impulse and a permanent force, both with variable direction and magnitude.     

On the Stability of Biped Locomotion

The stability of legged machines in locomotion is considered. The general machine has a rigid body to which legs are attached. Locomotion is performed on level smooth surfaces.     

Towards nonadaptive and adaptive control of manipulation robots

Control synthesis for robotic systems with a variable payload is considered. First, we synthesize a robust, nonadaptive decentralized control using an approximative system model. Then, we analyze the stability of an exact system model. We thus check whether the robotic manipulator is stabilized for all allowable payload variations. If the simple decentralized control cannot accommodate all expected payload variations we introduce additional load, nonadaptive, feedback loop. This global control requires force transducers to be implemented in manipulator joints. If such nonadaptive control cannot stabilize robotic manipulator trajectories we suggest another adaptive control scheme. This control scheme includes an algorithm for on-line identification of variable payload and adaptation of local gains.     

Contribution of suboptimal control of manipulation robots

Nonlinear model of an active spatial mechanism is considered as a set of subsystems each associated to one mechanical degree of freedom. For each decoupled subsystem, control, minimizing local criterion, is synthesized. Since the destabilizing influence of coupling among subsystems could be strong, global control is introduced in order to decrease suboptimality of the decentralized control applied. The control synthesis is demonstrated on an example of a six degree of freedom (DOF) manipulator.     

Observer-based fault diagnosis in manipulation robots

The problem of fault detection and isolation (FDI) in manipulation robots described by nonlinear dynamic models is studied. It is supposed that the FDI process is based on the bank of diagnostic observers. To design the nonlinear observers, original mathematical technique (so-called algebra of functions) is used. The procedures for obtaining the diagnostic observers based on the algebra of functions are developed. Different kinds of sensors and their influence on a quality of the FDI process are studied. The modeling results reflecting the relationships between the faults and the residuals are presented. Use of the FDI methods allows us to prevent the destruction of equipment and avoid great losses.     

Mathematical model of multiple manipulators: cooperative compliant manipulation on dynamical environments

The mathematical model of multiple non-redundant rigid robot manipulators performing cooperative work on a single dynamical object of which the motion is constrained by a dynamical environment is presented. The coordinated robots have to simultaneously move the object along a predetermined known trajectory on the constraint environment, exert a prespecified contact force on the environment, and regulate the internal force in the object. The manipulator dynamics, the object dynamics and the environment dynamics are taken into consideration, together with the material constraints imposed on the system (contact conditions between robots and object and between object and environment), and program constraints (specified internal forces, contact forces, object motion). The modelling procedure is illustrated by an example.