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A scene-level two-pass video rate controller for high efficiency video coding (HEVC) standard is proposed in this paper. The proposed rate controller is suitable for many pre-recorded applications in which encoded videos are transferred later on through a communication channel with limited bandwidth and buffering constraint. This rate controller operates in two passes. In the first pass, the video sequence is compressed and relevant information is collected. In the second pass, an optimal base quantization parameter (QP) for each video scene is calculated by simplifying the λ-domain rate-distortion model. Then, using the optimal base QP and the known QP cascading technique, a QP is computed for each picture in the scene. In this way, the quality of the compressed video is kept relatively constant during a scene and thus it provides a high-level perceptual quality for the compressed video. The base QP may be slightly modified during the second pass encoding by a fuzzy controller according to the second pass encoding results and the buffer status. The proposed rate controller has been implemented on H.265/HEVC standard reference software. Experimental results show that in comparison with the constant QP encoding and three known rate control algorithms the proposed algorithm provides a high-level quality for tested video sequences while the required buffering delay is low and the available bandwidth is fully used.

A fuzzy rate controller with buffer constraint in combination with a perceptual quality controller is proposed for streaming applications of the AVC/H.264 scalable (SVC) video. The bit rate of each video layer is controlled separately by the fuzzy controller that adjusts the quantization parameter (QP) on a group of pictures (GOP) basis. The QPs of pictures are computed from the GOP QP by the well-known QP cascading technique. While the fuzzy controller provides the buffering constraint for each video layer, the quality controller tries to improve the perceptual quality of the compressed video based on the foveated just-noticeable distortion (FJND) model. The quality controller regulates the QP of each macroblock around the picture QP based on the visibility threshold of the FJND model. In these applications, the initial buffering allows slight variations of the bit rate leading to produce a variable bit rate (VBR) video bit stream with consistent quality. Experimental results show that the proposed algorithm effectively adapts to the buffer size, while strictly prevents buffer overflow and underflow. In addition, incorporating the perceptual quality controller into the fuzzy rate controller achieves higher perceptual quality at the same bit rate.

Since the development of data centers, power management (i.e., assessment, consumption and monitoring) has been a great challenge among scientists and engineers. By emerging a new generation of data center in the form of Hyperscale cloud data centers (HCDC), this concern has become more devastating than ever. The huge physical scale and the high level of system utilization through large power compensating system are some of the main characteristics of today’s HCDC. The lack of appropriate power assessment from available power estimation models, prevents professionals from designing an accurate HCDCcapacity planning. In particular, during steady state workload processing at the high utilization rate of HCDCtechnology, the inlet cold temperature level rises up and this trace can be effect to the computable power consumption. In this article, we show how the ambient temperature have significant negative impact on power consumption and for an accurate and proper estimation of the power consumption of HCDC, we propose a temperature-aware power consumption model. The model is evaluated by SimWare for various server types and configurations and results prove the effectiveness and accuracy of the proposed model. At the end, we show the proposed model can be applicable for both homogeneous and heterogeneous HCDCs.

The new High Efficiency Video Coding (HEVC) standard is targeted for high-resolution video contents that are suitable for many high-delay video communications applications, such as video streaming. A few-rate control algorithms (RCAs) have been proposed for the HEVC in the literature. Almost all state-of-the-art RCAs proposed for the HEVC are optimized for constant bit rate low-delay applications. In order to reach a higher visual quality in high-delay applications, such as video streaming, a proportional integral derivative (PID)-fuzzy RCA with the buffering constraint is proposed for the HEVC in this paper. The proposed RCA is designed to minimize fluctuations of quantization parameter (QP) while the buffering constraints are fully obeyed. Unlike conventional fuzzy-PID algorithms that use a PID controller for control and a fuzzy system for tuning the PID parameters, the proposed algorithm uses a fuzzy controller with proportional, integral, and derivative inputs. A base QP is calculated for each group of picture (GOP) by the PID-fuzzy controller and determined QP offsets are added to the base QP to obtain the QP of frames at different temporal layers in the GOP. Experimental results indicate that high rate-distortion performance, fulfilled buffering constraint, and the high visual quality of compressed video are gained simultaneously by the proposed algorithm with low computational complexity.

In order to obtain haptic interaction with precise force feedback from the environment, for an exoskeleton, a robotic 2-jaw gripper is proposed. To reach this goal, a gripper is designed based on optimizing the link lengths to maximize the amount of weight that the gripper could hold and built with parallel jaws and two Force Sensitive Resistor (FSR) sensors for measuring the force applied on the jaws. The gripper is used as an end effector for a palletizing 3-DOF robotic arm and is interfaced to a computer using an Arduino board. The FSRs are both calibrated before object grasping, and as a result, the force exerted on each jaw while grasping objects is obtained. This data is consequently used to achieve four goals: detect an object presence, prevent the object from being damaged during grasp, evaluate the object weight through the coefficient of friction and obtain safe haptic feedback for a master exoskeleton (HEXON11Hand Exoskeleton of New technologies research center). The experimental results are provided within the mechanism relations and numerical simulation to validate the desired tasks.

This paper describes the design and kinematic optimization of a novel, underactuated, linkage driven exoskeleton mechanism to provide haptic force feedback to the index and thumb fingers. Existing exoskeletons are either not compatible with the human hand kinematic chain or so heavy that they cannot be compatibly installed on a human hand, which in turn affects the natural motion of the hand. In order to improve functionalities, the design of a novel (HEXON11Hand Exoskeleton of New technologies research center) based on a multi-criteria optimization is proposed to simultaneously maximize applied force to the finger and workspace of the attached exoskeleton. The optimization procedure consists of both the Perpendicular Impact Force (PIF) and the Global Isotropy Index (GIl), considering worst-case collision avoidance. Finally, the exoskeleton mechanism functionalities within the achieved link length through the optimization procedure are validated, and design is proposed for further fabrication.

The application of linear motor-driven stages as the feed drivers of CNC micro milling machine tools is growing. In addition to employ high speed and high precision equipment such as linear motor-driven stages, the precision of the machined contours is highly dependent on the capabilities of the servo controllers. In this paper, the design of a precise controller for a two-axis LMDS has been investigated for micro-milling applications. In such feed drives, disturbances such as friction, force ripples, and machining forces have adverse effects on the workpiece positioning precision due to the direct drive concept behind them. Therefore, in order to have an acceptable transient response and disturbance rejection properties, a two-degree-of-freedom proportional–integral–derivative controller was employed for each axis. To design this controller, the zero-placement method was used. To compensate disturbances and machining contour errors, the utilization of Kalman filter observers, neural networks, cross-coupled controllers, and different integration of them were studied. The controllers were experimentally examined for circular motions. An integrated controller consisted of a Kalman filter disturbance observer, a cross-coupled controller, and a well-designed two-degree-of-freedom proportional–integral–derivative controller resulted in a high contouring and tracking precision. The controller could also reduce the spikes caused by the friction at the motion reversal points such as the quadrants in circle trajectories.

Efficient actuation is an important requirement in electromechanical designs. Although hydraulic actuators are used extensively when high-magnitude forces are present in heavy machinery, they are not very energy-efficient. This paper aims to increase the efficiency of electro-hydraulic servo systems after introducing a controllable supply pressure and six mode of operation for different condition. This process allows for the system to have very low energy consumption whenever its environmental force agrees with its position reference signal. For this purpose, first, the electrohydraulic servo systems is modeled and a robust H∞ controller is designed for each mode of operation. The resulting control system works based on applying each mode strategy at right time to save energy. The effectiveness of this method is tested by conducting experiments on a hydraulic test rig and presenting the experimental results.

The high -efficiency video coding (HEVC) standard was introduced for high-resolution video contents suitable for many high-delay applications. The bit rate of compressed video is controlled in almost all digital video applications according to the practical constraints such as available channel bandwidth and allowed delay or buffering constraint. In high-delay video applications such as video broadcasting and video streaming applications, variable-bit-rate videos can provide a higher visual quality than constant-bit-rate videos. In this paper, a rate control algorithm (RCA) for high-delay applications of the HEVC standard with buffering constraint is proposed. A fuzzy controller and a virtual buffer are used in the proposed RCA. The fuzzy controller is designed to minimize the fluctuations of quantization parameter (QP) while the buffering constraint is obeyed. It computes a base QP for each group of pictures (GOP) to prevent unnecessary fluctuations of QP at GOP level and thereafter provide a higher visual quality. Experimental results show that not only the bit rate and but also buffering constraints are fully maintained but also the objective quality of compressed video is well preserved. Moreover, the proposed RCA provides smooth QP and peak signal-to-noise ratio close to constant QP case for encoded videos that means high subjective quality.

In this paper, a rate control algorithm for variable bit rate video applications with buffer constraint is proposed. The proposed algorithm utilizes a fuzzy rate controller and a perceptual quality controller. The fuzzy controller computes a base quantization parameter (QP) for each video picture to provide the buffer constraint. Then, the perceptual quality controller uses a human visual system (HVS) model namely foveated just-noticeable distortion (FJND) model to improve the perceptual quality of encoded video by modulating the QP of macroblocks around the picture QP. The proposed rate control algorithm has been implemented on the JM H.264/AVC reference software and obtained experimental results show that it can produce encoded videos with high perceptual quality while the buffering constraint is strongly obeyed.

Digital video stabilization (DVS) allows acquiring video sequences without disturbing jerkiness, removing unwanted camera movements. A good DVS should remove the unwanted camera movements while maintains the intentional camera movements. In this article, we propose a novel real-time DVS algorithm with a short-delay. The proposed DVS compensates the camera jitters applying an adaptive fuzzy filter on the global motion of video frames. The adaptive filter is an infinite impulse response (IIR) non-causal filter which is tuned by a fuzzy system adaptively to the camera motion characteristics. The fuzzy system itself is also tuned during operation according to the amount of camera jitters. The fuzzy system uses two inputs which are quantitative representations of the unwanted and the intentional camera movements. The global motion of video frames is estimated based on the block motion vectors which resulted by video encoder during motion estimation operation. Experimental results indicate a good performance for the proposed algorithm.

Gas metal arc welding (GMAW) process is one of the most widespread welding processes in industries and using robots to manipulate the welding torch leads to excellent production quality, reliability, efficiency, and cost-effectiveness. In the previous researches, the automatic GMAW system including robotic arm, moving workpiece table and vision capability are developed for real-time seam tracking and welding of complex parts. Despite a precise tracking result achieved by the robotic methods, the welding metal deposit is uncontrolled and generates a varying bead shape on the seam. This problem comes from the variable relative speed between the torch and the curved seam and deteriorate the welded product mechanical properties. In this article, a novel approach is proposed to adjust the GMAW parameters in real-time according to the measured relative speed. Based on the process affecting parameters, a control algorithm is designed. Then some mechatronic elements are added to the system to accomplish the process control. The experimental results indicate the approach efficiency on the bead shape uniformity.

This paper presents a study on electro-hydraulic servo system for the purpose of position control using a compatible linear model. The system has high level of nonlinearity and linearization introduces extra error in system model. In order to reduce this error several methods of linearization uncertainty are discussed. In spite of applying Taylor's series for all methods, several procedures are used for considering uncertainty on linearization constants. In the first procedure, a simple bound is considered for each linearization constant. In the second procedure, a polytope is extracted for the uncertainty by a graphical method. Finally, a procedure with less conservativeness and less restriction is proposed. This procedure is used to extract the linear model of the electro-hydraulic servo system for the task of position control. The resulting model is used to synthesize an output-feedback H∞ controller for the EHSS using a Linear Matrix Inequality (LMI)-based approach. The effectiveness of the proposed method is demonstrated by simulation and experimental results. The results showed that the procedure is less conservative and has the fastest operation without any overshoot.

Electro-Hydraulic Servo Systems (EHSS) are employed as actuators to track the desired trajectory and exert force in heavy-duty industrial applications. The EHSS is often prone to problems such as leakage and actuator seal damage during the course of its utilization. These faults which cannot be directly detected from current sensor values, can eventually result in complications and degrade control performance. The goal of this research is to use representation learning concepts to detect these faults with decreased complexity. The objective is to find a nonlinear mapping to transform raw data into another space in which classification becomes easier. The data are driven from the hydraulic supply pressure signal. To find the mapping, a custom-built optimization algorithm is proposed along with a suitable cost function to carry out the search for the new representation. The performance of the resulting transformation is tested in an experimental setting to show the merits of the proposed method.

SUMMARYThis paper presents a new observer-based adaptive controller for handling an object withunknowngeometry, center of mass, and inertia using a cooperative robotic system. The cooperative robotic system comprises three Cartesian robots, where robots and the grasped object form a closed-loop kinematic chain. The unknown object is approximated by three virtual links of unknown lengths rigidly attached to one another at the object's center of mass (COM). Due to the unknown COM and unknown inertia of the object, the lengths and inertia of these virtual links are unknown, resulting in kinematic and dynamic uncertainties in the control system. A parameter estimator is proposed to estimate the object's COM to compensate for kinematic uncertainties of the system. Moreover, a new dynamic adaptation law is developed to cope with dynamic uncertainties of the object. The dynamic equations of the cooperative system are transformed from joint space into task space. These task space dynamics are transformed into object space by passively decomposing the dynamics into two decoupled systems, i.e.lockedandshapedsystems. An adaptive controller is developed for the locked system, and the shaped system is controlled by a composite controller based on a PD controller plus a stabilizing damping term. The stability of the proposed controllers is shown using the passivity concept and Lyapunov theorem. Simulation results show that the closed-loop position error asymptotically converges to zero. It is also shown that kinematic and dynamic adaptation parameters converge to real and bounded values respectively.

Background Telesurgery delivers surgical care to a ‘remote’ patient by means of robotic manipulators. When accurate positioning of the surgeon's tool is required, as in microsurgery, physiological tremor causes unwanted imprecision during a surgical operation. Accurate estimation/compensation of physiological tremor in teleoperation systems has been shown to improve performance during telesurgery. Method A new control architecture is proposed for estimation and compensation of physiological tremor in the presence of communication time delays. This control architecture guarantees stability with satisfactory transparency. In addition, the proposed method can be used for applications that require modifications in transmitted signals through communication channels. Stability of the bilateral tremor-compensated teleoperation is preserved by extending the bilateral teleoperation to the equivalent trilateral Dual-master/Single-slave teleoperation. The bandlimited multiple Fourier linear combiner (BMFLC) algorithm is employed for real-time estimation of the operator's physiological tremor. Results Two kinds of stability analysis are employed. In the model-base controller, Llewellyn's Criterion is used to analyze the teleoperation absolute stability. In the second method, a nonmodel-based controller is proposed and the stability of the time-delayed teleoperated system is proved by employing a Lyapunov function. Experimental results are presented to validate the effectiveness of the new control architecture. The tremorous motion is measured by accelerometer to be compensated in real time. In addition, a Needle-Insertion setup is proposed as a slave robot for the application of brachytherapy, in which the needle penetrates in the desired position. The slave performs the desired task in two classes of environments (free motion of the slave and in the soft tissue). Conclusion Experiments show that the proposed control architecture effectively compensates the user's tremorous motion and the slave follows only the master's voluntary motion in a stable manner. Copyright © 2012 John Wiley & Sons, Ltd.

Welding is one of the most common method of connecting parts. Welding methods and processes are very diverse. Welding can be of fusion or solid state types. Arc welding, which is classified as fusion method, is the most widespread method of welding, and it involves many processes. In gas metal arc welding or metal inert gas–metal active gas, the protection of the molten weld pool is carried out by a shielding gas and the filler metal is in the form of wire which is automatically fed to the molten weld pool. As a semi-metallic arc process, the gas metal arc welding is a very good process for robotic welding. In this article, to conduct the metal active gas welding torch, an auxiliary ball screw servomechanism is proposed to move under a welder robot to track the welded seam. This servomechanism acts as a moving fixture and operates separately from the robot. At last, a decentralized control method based on adaptive sliding mode is designed and implemented on the fixture to provide the desired motion. Experimental results demonstrate an appropriate accuracy of seam tracking and error compensation by the proposed method.

The second version of the high-efficiency video coding standard introduced a scalable extension, which is called scalable high-efficiency video coding. It is necessary to design appropriate rate controllers for this extension based on the specific application requirements. According to delay and buffering constraints, rate control algorithms are divided into constant bit rate and variable bit rate (VBR) algorithms. Our focus is on high-delay applications like streaming and broadcast for which VBR controllers are suitable. Our proposed VBR controller utilizes a fuzzy logic-based algorithm to control long-term average bit rate while preventing buffer overflow or underflow. Targeting perceptual quality, the proposed algorithm has been implemented at the group of pictures level to minimize unnecessary fluctuations of quantization parameter and consequently minimizing video quality fluctuations. Experimental results show a high performance in terms of rate control and quality of the compressed video for the proposed algorithm.

A novel technique for implementing statistical multiplexing (StatMux) of broadcast services over Digital Video Broadcasting for Handhelds (DVB-H) channels is proposed. DVB-H uses a time-sliced transmission scheme to reduce the power consumption used for radio reception part in DVB-H receivers. Due to the time-sliced transmission scheme, the implementation of known StatMux methods for DVB-H application presents some challenges which are addressed in this paper. The proposed StatMux technique is implemented in conjunction with the time-slicing transmission scheme. The combination is similar to a time division multiplexing (TDM) scheme. The proposed StatMux method considerably decreases the end-to-end delay of DVB-H services while it maximizes the usage of available bandwidth. Moreover, the proposed method can effectively decrease the channel switching delay of DVB-H services. Simulation results show a high performance for the proposed StatMux method.

A novel joint video encoding and statistical multiplexing (StatMux) method for broadcasting over digital video broadcasting for handhelds (DVB-H) channels is proposed to improve the quality of encoded video and to decrease the end-to-end delay in a broadcast system. The main parts of end-to-end delay in a DVB-H system result from a time-sliced transmission scheme that is used in DVB-H and from the bit rate variations of service bit streams. The time-sliced transmission scheme is utilized in DVB-H to reduce the power consumption of DVB-H receivers. Variable bit rate (VBR) video bit streams are used in DVB-H to improve the video quality and compression performance. The time-sliced transmission scheme has increased the channel switching delay, i.e., switching to a new audio-visual service, in DVB-H. The used VBR bit streams increase the required buffering delays in the whole system. The different parts of end-to-end delay in a DVB-H system can be affected by the used video encoding and multiplexing methods. Different scenarios for encoding and StatMux of video sources for DVB-H application are studied in this paper. Moreover, a new method for jointly encoding and StatMux of video sources is proposed that not only decreases the end-to-end delay but also improves the average quality of compressed video by dynamically distributing available bandwidth between the video sources according to their relative complexity. Performance of the proposed method is validated by simulation results.

A novel semi-fuzzy (SF) rate control algorithm (RCA) for variable bit rate (VBR) video applications is proposed. The proposed RCA is optimized to provide high quality compressed video bit streams in a wide operating range from constant quality to nearly constant bit rate. Thanks to a low degree of computational complexity, it is suitable for real-time applications of VBR video. The proposed RCA operates under given buffer size, delay and quality constraints. It provides a VBR video bit stream by controlling the quantization parameter (QP) on a picture basis. The QP is mainly controlled by a fuzzy rate controller and a deterministic quality controller, which are optimized such that they minimize the variation of quality to provide encoded video with high and stable visual quality. The proposed RCA has been implemented in an H.264/AVC video codec and the experimental results show that it provides a high-level average quality for encoded video while strictly obeying the buffering delay and quality constraints.

Language teaching is an important device to expand and introduce culture to the other nations. Rule-governed structures are necessary for better understanding and learning of one language. This article aims at introducing the patterns of the structures of Persian simple sentences; moreover it describes these patterns with some examples from Persian to help the learners (especially non-native learners) have better understanding of them. DOI: 10.5901/jesr.2016.v6n1p94

A novel method is proposed which minimizes the tune-in time of "channel zapping", i.e. changing from one audiovisual service to another, in IP datacasting (IPDC) over Digital Video Broadcasting for Handheld terminals (DVB-H). DVB-H uses a time-sliced transmission scheme enabling a receiver to turn radio reception off for those time-slices that are not of interest to the user and thus reducing the power consumption used for radio reception. One of the significant factors in tune-in time is the time from the start of media decoding to the start of correct output from decoding, which is minimized when a time-slice starts with a random access point picture such as an independent decoding refresh (IDR) picture in H.264/AVC standard. In IPDC over DVB-H, encapsulation to time-slices is performed independently from encoding in a network element called IP encapsulator. At the time of encoding, time-slice boundaries are typically not known exactly, and it is therefore impossible to govern the location of IDR pictures relative to time-slices. It is proposed that an additional stream consisting of IDR pictures only is transmitted to the IP encapsulator, which replaces pictures in a normal bit stream with IDR pictures according to time-slice boundaries in order to achieve the minimum tune-in delay. Replacing pictures causes a mismatch in the pixel values of the reference pictures between the encoder and decoder and the mismatch error is propagated in the reconstructed video. It has to be ensured that the propagated error is subjectively negligible. Furthermore, the "spliced" stream resulting from the operation of the IP encapsulator should comply with the Hypothetical Reference Decoder (HRD) specification of H.264/AVC. Error propagation caused by the proposed splicing method is analysed and a video rate control system is proposed to satisfy the HRD requirements for the spliced stream. Simulation results show that in addition to fulfilling H.264/AVC compliancy, good average quality of decoded video is achieved with minimum tune-in delay and complexity

A fuzzy-proportional-integral (PI) rate control algorithm (RCA) for broadcasting applications of the high efficiency video coding (HEVC) standard is proposed in this paper. In this application controlled variable bit rate video bit streams are preferred to constant bit rate streams. A fuzzy-PI controller and a virtual buffer are used in our algorithm to calculate a base quantization parameter (QP) for each group of picture without using any rate-distortion model that leads to a low level of computational complexity. Fulfilled buffering constraint and high visual quality with damped unnecessary QP fluctuations must be reached at the same time. It is obvious from experimental results that these necessities are fully maintained by the proposed RCA.

In this paper a new fuzzy rate control algorithm is proposed for variable bit rate video applications of the High Efficiency Video Coding (HEVC) standard. The proposed controller considers given buffer size and target bit rate as constraints for control. In fact, it provides a variable bit rate video bit stream by controlling the quantization parameter (QP) on frame based. The QP for each frame is controlled by the fuzzy controller such that to minimize fluctuations in the visual quality of compressed video. The proposed algorithm has been implemented in the HEVC standard reference software (HM). Experimental results show that it provides an average quality, in terms of PSNR, similar to the HM rate control method for encoded video whereas having much less buffering delay.

A fuzzy rate control algorithm (RCA) with buffer constraint is presented for H.264/SVC standard with independently controlling each layer. By calculating the variation of quantization parameter (QP) instead of QP itself on group of pictures (GOP) level, this algorithm can be used efficiently for video streaming applications. The initial buffering in these applications allows slight variations in bit rate leading to produce a variable bit rate video bit stream with a consistent quality. A low computational complexity makes this controller suitable for real time applications. Experimental results show that the proposed algorithm effectively adapts itself to available buffer space, while strictly preventing it from overflow and underflow so that a PSNR gain up to 0.5dB in some cases is obtained.

This paper presented a fuzzy rate control algorithm for scalable extension of H.264/AVC (H.264/SVC video coding standard). The algorithm operates on the group of picture (GOP) level of scalable layers. It aggregates the bit streams of all scalable layers in a virtual buffer and adjusts the QP of the base layer according to a feedback signal from the buffer status. Considering the dependency of SVC layers, the QPs of the enhancement layers are computed with respect to the derived QP of the base layer. This method guarantees a constant relative higher quality for each enhancement layer. From the quality consistency point of view, as well as delay constraint, the algorithm is optimized to be used for a wide range of variable bit rate (VBR) applications. Simulation results show that the proposed fuzzy controller provides much higher average quality in comparison with the constant QP (CQP) method while, the buffer constraint is completely obeyed.

In the original publication, the affiliations of the two authors were incorrectly written as “University of Sistan and Bluchestan” when it should be “University of Sistan and Baluchestan.” The correct affiliations are presented in this erratum.

In the present paper, the objective of hybrid impedance control is specified and a robust hybrid impedance control approach is proposed. Based on the concept of hybrid control, the task space is decomposed into position and force controlled subspaces. Impedance control is used in the position controlled subspace. Desired inertia and damping are applied in the force controlled subspace to meliorate the dynamic behavior of robot manipulator. Robust controller using the variable structure model reaching control (VSMRC) is introduced that can realize the objective impedance in the sliding mode in finite time. In order to overcome the chattering effect due to sliding mode approach, fuzzy logic methodology is employed in the control system. In addition, the reaching transient response is undertaken with prescribed quality. Simulating the control system for a 6DOF PUMA560 robot confirms the validity and effectiveness of the proposed control system.

In the present paper, the objective of hybrid control is specified and an adaptive hybrid force/motion control approach is proposed. Based on the concept of hybrid control, the task space is decomposed into position and force controlled subspaces. An adaptive scheme is presented which makes the controller robust when the robot is in interaction with an unknown non-rigid environment. By using the classical Lyapunov method, it is demonstrated that the proposed control law ensures the tracking of the unconstrained components of the desired end-effector trajectories, with regulation of the desired contact force along the constrained direction. Simulation results verify the effectiveness of our prosperous adaptive hybrid control in robot-environment interaction.

This paper proposes a lossless data hiding (LDH) scheme on uncompressed video data based on a multi-level histogram shifting mechanism in integer wavelet transform (IWT) domain. The proposed method enables the exact recovery of the original host signal upon extracting the embedded information, if the watermarked image is not affected by any other process. In the proposed scheme, the approximation subband image of the luminance component of a video frame is computed. Then, it is divided into non overlapping blocks. In each block, the differences between the neighboring elements are computed and a histogram is made on the difference values. The secret data are embedded into the blocks based on a multi-level shifting mechanism of the histogram. Experimental results show that proposed scheme can hide a large amount of information within a video frame with a high degree of robustness against H.264/AVC encoding.

This paper addresses a new control scheme for bilateral telesurgical system with flexible links surgical robot. In this regard, hybrid structure of feedback and feedforward controller is suggested for flexible slave robot. This approach utilizes capability of Input Shaping (IS) as feedforward controller to reduce vibration at robot's end tip and the feedback controller based on collocated Proportional-Derivative (PD) for control rigid body motion of the system. Stability of closed loop input shaper for nonlinear systems is discussed for the first time in this article. The stability conditions for overall system with constant communication time delay are derived using lyapunov method. Due to the independence of the system parameters, combination of these controllers results stability robustness to parameter uncertainties. Moreover, It is shown that reshaped master command to slave's controller improves tracking performance in the presence of robot flexibility. Simulation results are used to verify the main theoretical points of this paper and demonstrate the effectiveness of proposed control framework in terms of input tracking and vibration suppression.

Digital video stabilization (DVS) allows acquiring video sequences without disturbing jerkiness, removing unwanted camera movements. A good DVS should remove the unwanted camera movements while maintains the intentional camera movements. In this article, we propose a novel DVS algorithm that compensates the camera jitters applying an adaptive fuzzy filter on the global motion of video frames. The adaptive fuzzy filter is a simple infinite impulse response filter which is tuned by a fuzzy system adaptively to the camera motion characteristics. The fuzzy system is also tuned during operation according to the amount of camera jitters. The fuzzy system uses two inputs which are quantitative representations of the unwanted and the intentional camera movements. The global motion of video frames is estimated based on the block motion vectors which resulted by video encoder during motion estimation operation. Experimental results indicate a good performance for the proposed algorithm.

In this paper, a robust lossless data hiding scheme on uncompressed video data based on histogram distribution constrained (HDC) scheme is proposed. The proposed method is a reversible data hiding algorithm which enables exact recovery of the original video without any distortion after extracting hidden information, if the watermarked video is not affected by any other process. The algorithm is robust against H.246/AVC video compression. In the proposed method, the luminance components of video frames are used to embed the watermark data bits. The luminance component is divided into non-overlapping blocks and the arithmetic difference of each block is computed. In the next step, the hiding data are embedded into the blocks by shifting the arithmetic difference values. The performance of the proposed algorithm is evaluated with respect to imperceptibility, robustness against H.264 video coding and data payload capacity by simulations. Simulation results demonstrate a high performance for the proposed method.

Piezoelectric actuators are widely used in micromanipulation tasks such as Atomic Force Microscopy and Cell Manipulation. However, the hysteresis nonlinearity and the creep reduce their fidelity and cause difficulties in the micromanipulation control procedure. Besides, variation of temperature and external loads could change the model parameters identified for the piezo actuator. In this paper, a novel feedforward-feedback controller is proposed. The Prandtl-Ishlinskii model is utilized to linearize the actuator hysteresis in feedforward scheme and a sliding mode based impedance control with perturbation estimation is used to cancel out the thermal and external load disturbances in feedback scheme. The efficiency of the proposed controller is verified by experiments.

Digital Video Broadcasting for Handheld terminals (DVB-H) is an ETSI specification for delivering broadcast services to battery-powered handheld receivers [4, 7]. DVB-H is mainly based on the DVB-T specification for digital terrestrial television. Comparing to digital terrestrial television, handheld television is much more difficult from technical points of view. First, mobile terminals have very small antenna size comparing to standard television antennas. Consequently, handheld terminals need stronger signals than standard television. Second, mobile reception is expected everywhere, especially inside buildings and in vehicles. This demands extraordinary robustness for transmission signal. Third problem of handheld terminals is limited power supply which restricts consumption of TV content. The DVB-H mobile TV standard addresses these issues by adding a number of features to DVB-T standard. DVB-H adds functional changes in the link and physical layers while it is backward compatible with DVB-T. In the link layer, DVB-H has two new elements when compared to DVB-T: Time Slicing and Multiprotocol Encapsulation Forward Error Correction (MPE-FEC). In the physical layer, DVB-H also has two extensions to DVB-T: DVB-H Signaling and 4K-Mode OFDM. More details about these extensions are presented in the sequel.

This paper presents a rate control (RC) algorithm for the scalable extension of the H.264/AVC video coding standard. The proposed rate controller is designed for real-time video streaming with buffer constraint. Since a large buffer delay and bit rate variation are allowed in this kind of applications, our proposal reduces the quantization parameter (QP) fluctuation to provide consistent visual quality bit streams to receivers with a variety of spatio-temporal resolutions and processing capabilities. The low computational cost is another characteristic of the described method, since a simple lookup table is used to regulate the QP variation on a frame basis.

The slave robot of the macro-micro teleoperation system presented in this paper is a 1-DOF piezo actuator including hysteresis nonlinearity. This nonlinear behavior makes robot control a complex task. In this research the nonlinear and uncertain dynamics of the slave robot has been entered directly into the teleoperation control loop. The LuGre friction model is used as the estimator of the hysteresis loop to cancel out this undesirable term. A 2-DOF master-slave system is decomposed into two 1-DOF systems: a shape system representing the master-slave position coordination, and a locked system representing the dynamics of the coordinated system. For making the closed-loop teleoperation system passive against dynamic parameter uncertainty and force measurement inaccuracy, four virtual flywheels are designed. In this way, the energy generated by troublesome terms inside controllers (i.e. the terms which may endanger passivity of the controller) would be taken from the bounded kinetic energy deposited on these flywheels. Simulations are performed to show effectiveness of the proposed controllers.

The slave robot in this research is a 1-DOF piezo actuatorwhich includes hysteresis nonlinearity. Nonlinear hysteresis behavior makes robot control a complex task. In this research, the nonlinear and uncertain dynamics of the slave robot has been considered through the teleoperation control loop. LuGre friction model is used as the estimator of the hysteresis loop. An impedance controller for the master side and a sliding-mode-based impedance controller for the slave side have been proposed. The latter is a sliding mode controller, because the plant is nonlinear and uncertain. Also, it is an impedance controller providing both high performances during contact and excellent tracking in free space motion. These controllers make teleoperator robustly stable against uncertainties and bounded constant time delay. Meanwhile, scaling factors, known as sources of instability, have no disturbing effect. After canceling the nonlinear term out of the teleoperator by the controllers, stability of the entire system will be guaranteed by Llewellyn's absolute stability criterion. Performance of the proposed controllers is investigated through simulation.

A joint video encoding and statistical multiplexing (StatMux) method for broadcasting over DVB-H (digital video broadcasting for handhelds) channels is proposed to decrease the channel changing delay. DVB-H uses a time-sliced transmission scheme to reduce the power consumption used for radio reception in DVB-H receivers. Channel changing delay, i.e. changing from one audio-visual service to another, increases due to the time slicing scheme in DVB-H. The proposed method decreases the buffering delay as a part of channel changing delay by dynamically distribution of available bandwidth between the video sources according to their temporal bit rates. Moreover, the proposed method in combination with the time-slicing decreases the overall channel changing delay by other means.

This paper introduces a method for unequal error protection (UEP) of media data in a time-sliced DVB-H channel. Media datagrams are assigned priorities using some a-priori knowledge. Datagrams covering a certain period of playback time are first grouped based on the priority assignment. Each group is then protected using Reed?Solomon forward error correction (FEC) codes and packed into multi-protocol encapsulation (MPE) FEC frames as defined by the DVB-H standard. All MPE-FEC frames for a certain period of playback time are then sent back to back without any delay between these MPE-FEC frames. This method of UEP is generic and can be tuned according to the priority assignment algorithm. Simulations using H.264/AVC video were conducted to evaluate the performance of the proposed method. It used a simple priority assignment algorithm. The resulting rate distortion graphs show good performance and an average luma peak signal-to-noise ratio (PSNR) improvement of up to 0.8 dB was achieved.

In this paper, we propose a real-time, low-complexity video rate control algorithm designed to obey buffer constraints. The algorithm is optimized for streaming and local recording applications in mobile devices. Today, most mobile phones include a digital camera that can be used to capture video. The on-phone processor technology has become powerful enough to encode video in real-time. The resulting file can, for example, be archived in the phone's memory, or (progressively or as one block) downloaded, through the 3G mobile network, Bluetooth, or WLAN, to Internet-connected computer systems. From here, all forms of multimedia transmission, such as streaming, file sharing, or multimedia mail become possible. In local recording and streaming applications on a mobile phone, we assume that no memory for storage of uncompressed video is available. Therefore, look-ahead and multi-path rate control is not possible. Furthermore, considering the processing power and, more importantly, battery life constraints in mobile devices, the proposed algorithm needs to be as simple as possible. The described algorithm implements a variable bitrate (VBR) by controlling the quantization scale (QS) on a per picture basis. The QS is calculated based on two other QSs, which correspond to constant rate and constant quality rate controls. The algorithm utilizes the variable bitrate benefits as much as possible so as to minimize the variation of the QS scale, and to provide encoded video with high visual quality. Although it strictly obeys buffering constraints as discussed later, the experimental results show that it allows encoded video at average quality levels significantly higher than reported in earlier works

In this paper we propose a general and precise rate-distortion (RD) model for standard video codecs, including MPEG-4, H.263 and AVC H.264. The model can be used in almost all video rate control algorithms for different applications, from one-pass to multi-pass, and from constant rate to constant quality. It is designed taking into account previous theoretical results, and based on new assumptions which are confirmed by comprehensive practical experiments. We conceptually divide the RD model into two separate parts. The first part is codec specific and reflects the codec's properties. The second part is video content specific and describes the interaction between the video content and the encoder. This division provides several advantages. The model performs more precisely but needs less updating efforts. Furthermore, in this paper we introduce a simple complexity measure for the video content. As an example, we parameterized the RD model by the complexity measure for the estimation of intra frame bits. This example can be used for complexity estimation in a start frame and in the scene cuts. The experimental results show that both the RD model and complexity measure perform well, with high precision as estimation tools.

In this paper we propose a special bit allocation method which can be used in most rate control algorithms in variable rate video applications. In real-time video communication applications, we need a constant short-term average bitrate, while in variable bitrate applications such as streaming and local recording applications, a constant long-term average bitrate is sufficient and more short-term variation in bitrate is acceptable. In comparison with constant bitrate video, a variable bitrate video can provide better visual quality and coding efficiency for compressed video sequences. Furthermore, while more variation in bitrate is possible we have additional degrees of freedom to control the encoding parameters. We propose a special bit allocation algorithm to take advantage of this freedom in variable bitrate video. We introduce a new type of frame namely SPP frame (SPecial P frame) that can be used in combination with I, P, B and other types of frames in different encoders including H.263, MPEG-4 and H.264/AVC encoders. We propose a simple method to implement the SPP frames independently of the rate control algorithm. The experimental results show that the SPP frames can considerably increase the total average quality of variable rate encoded video