Sendren Sheng-Dong Xu

Study of Nonsingular Fast Terminal Sliding-Mode Fault-Tolerant Control

This paper studies fault-tolerant control (FTC) designs based on nonsingular terminal sliding-mode control and nonsingular fast terminal sliding-mode control (NFTSMC). The proposed active FTC laws are shown to be able to achieve fault-tolerant objectives and maintain stabilization performance even when some of the actuators fail to operate. In comparison to existing sliding-mode control (SMC) fault-tolerant designs, the proposed schemes not only can retain the advantages of traditional SMC, including fast response, easy implementation, and robustness to disturbances/uncertainties, but also make the system states reach the control objective point in a finite amount of time. Moreover, they also resolve the potential singularity phenomena in traditional terminal and faster terminal SMC designs; meanwhile, the proposed NFTSMC fault-tolerant scheme also possesses the benefit of faster state convergence speed of NFTSMC. Finally, the proposed analytical results are also applied to the attitude control of a spacecraft. Simulation results demonstrate the benefits of the proposed schemes.

Study of Nonlinear Integral Sliding Mode Fault-Tolerant Control

This paper studies an active fault-tolerant control (FTC) design based on an integral sliding mode control (ISMC) strategy for a class of uncertain nonlinear systems. It is shown that under the proposed scheme, the closed-loop system can tolerate certain allowable actuator faults whenever fault detection and diagnosis information is available, and the scheme also retains the main advantages of the ISMC technique. These advantages include robustness, rapid response, and ease of implementation. Moreover, the state response of the resulting closed-loop system under normal operation and different fault conditions is predictable from the response of a preselected fault-free certain system, which can be determined by the designer. Consequently, the engineer has the flexibility in selecting an (optimal) control law for the preselected system according to the system requirements. The analytical results obtained are also applied to the attitude control of a spacecraft. The simulation results clearly demonstrate the benefits of the proposed scheme.

SSIM-Based Quality-on-Demand Energy-Saving Schemes for OLED Displays

This paper investigates how to precisely transform images displaying color on organic light-emitting diodes (OLEDs) in real time for the purpose of energy-saving that meets the personal viewing quality requirements based on the structural similarity (SSIM) assessment. These methods could be applied to real-time energy-saving transformation of any displaying media, including video playback on OLEDs, and it will save up to 20% of the displaying power consumption based on the predicted SSIM = 0.9, which has very good image quality after the transformation.

Modeling and motion analysis of four-Mecanum wheel omni-directional mobile platform

Because of its comprehensive and flexible sporty performance, omni-directional mobile platform is widely used in industrial production, daily life as well as military fields. Disposed on four terminals of the vehicle body, each wheels movement is controlled by an independent motor respectively. In this paper, we provide a structural analysis and motion resolving solution to the platform based on four separate Mecanum wheels. We then study the proper layouts that meet the conditions required for full-directional movements. Finally, we build the perspective mathematical model in its kinematics and dynamics terms.

Optimal Fuzzy Controller Design Using an Evolutionary Strategy- Based Particle Swarm Optimization for Redundant Wheeled Robots

This paper presents an optimal fuzzy controller design method using an evolutionary strategy-based particle swarm optimization (ESPSO) to four-wheeled redundant mobile robots, called FC-ESPSO. In comparison with conventional fuzzy controllers, this approach takes the advantages of evolutionary strategy, fuzzy control, and PSO, thereby obtaining better population diversity, avoiding premature convergence, and achieving self-adaptive redundant control. This hybrid computing is then applied to develop an optimal fuzzy controller of redundant wheeled robots. The optimal parameters of the dynamic controller are self-adaptive via the proposed FC-ESPSO to resolve trajectory-tracking problem. Simulation results are given to exhibit the merits of the proposed FC-ESPSO than other related control methods for redundant wheeled robots.

Real-time quality-on-demand energy-saving schemes for OLED-based displays

This paper proposes the novel methods which are able to real-timely and dynamically transform the RGB values of images displayed on the organic light-emitting diode (OLED), in the case where the personal viewing quality requirements are able to be met based on the peak signal to noise ratio (PSNR) prediction. The methods could also be applied to the real-time energy-saving transformation of any displaying media including the video playback on OLED. Simulation results show that by the proposed methods it will own the advantage of efficiently saving the displaying power consumption up to 51%.

Multi-root I/O virtualization based redundant systems

Redundancy, a method being designed to prevent failures due to software/hardware problem, is one of the most common applications in fault-tolerance systems. In this paper, we provide a multi-root I/O virtualization (MR-IOV) based redundant system architecture which supports high performance, reliability, and scalability to improve conventional redundant architecture with hardware multiplexer for the fail-over function. In order to fix this drawback, we proposed a redundant architecture to save these statuses in the shared memory, and the backup system will apply the states to fail-over primary host. From experiment results, we observe that the proposed architecture is feasible and it is better than the conventional redundant architecture.

Super-Twisting-Algorithm-Based Terminal Sliding Mode Control for a Bioreactor System

This study proposes a class of super-twisting-algorithm-based (STA-based) terminal sliding mode control (TSMC) for a bioreactor system with second-order type dynamics. TSMC not only can retain the advantages of conventional sliding mode control (CSMC), including easy implementation, robustness to disturbances, and fast response, but also can make the system states converge to the equivalent point in a finite amount of time after the system states intersect the sliding surface. The chattering phenomena in TSMC will originally exist on the sliding surface after the system states achieve the sliding surface and before the system states reach the equivalent point. However, by using the super twisting algorithm (STA), the chattering phenomena can be obviously reduced. The proposed method is also compared with two other methods: (1) CSMC without STA and (2) TSMC without STA. Finally, the control schemes are applied to the control of a bioreactor system to illustrate the effectiveness and applicability. Simulation results show that it can achieve better performance by using the proposed method.

Global Stabilization for a Class of Genuinely Nonlinear Systems With a Time-Varying Power: An Interval Homogeneous Domination Approach

This paper addresses the problem of global state feedback stabilization for a class of genuinely nonlinear systems with a time-varying power. By revamping the so-called adding a power integrator technique and the homogeneous domination approach, a new design method called interval homogeneous domination approach is proposed to delicately design a state feedback control law that renders the nonlinear systems globally asymptotically stable. The novelty of the proposed scheme owes to the systematic fashion that provides a distinct perspective to solve the stabilization problem for the nonlinear systems with a time-varying power.

Edge enhanced SIFT for moving object detection

This paper is to report our study on the moving object detection from surveillance images. For motion detection, some existed methods are used to find specific features between images and then to define the moving speeds of objects. However, human-created features may be difficult to define and to acquire especially when the objects are unknown. In this paper, the scale-invariant feature transform (SIFT) method is adopted to define features for motion detection. In the image, SIFT can be used to catch the properties of scale and rotation invariant. Even if the foreground target is partially obscured and the image is taken in a different angle and distance, SIFT can still have nice matching performances. However, when applied in detecting moving objects, SIFT does not work well due to finding incorrect features in the match. In this study, an enhanced edge detection method is proposed for Laplace of Gaussian (LoG) based SIFT. From the simulation results, it is evident that our proposed method can find more feature matching in the video image.