Cheng Dong Wu

Moving Object Detection Based on Improved Variational GAC Model

In view of the detection of moving object in video sequence, the traditional moving object detection algorithms are researched. The paper presents a new algorithm for object detection based on initial contour and improved variational GAC model. First, this method built up background model utilizing Gaussian mixture model and background subtraction to extract initial contour of the object; taking initial contour as initial value of curve evolution. Then, an improved restriction item is introduced into variational GAC vector model, the proposed restriction item that is a nonlinear hear equation with normalized diffusion rate, therefore re-initialization procedure of level set function is completely eliminated. Iteration number of curve evolution and run time is reduced. The experimental show that accurate contour of moving object is got and this algorithm is effective and feasible in real video environment.

The Research of the Four-Bar Bionic Active Knee

The robot joints are usually rotational axis by two link joints, bionic features is not strong. The shortcomings of intelligent MR damper control multi-axis bionic knee can only provide resistance and certain sizes to regain momentum, cannot provide larger power, therefore this paper gives by the multi-axis four-bar structure, ball screw transmission multiaxial bionic active knee institutions. And analysis the human leg institutions and commonly used two-bar structure, through multi-variable optimization method to solve the design parameters of knee joint structure, the motor angular velocity and torque. And established in a bionic active the knees virtual prototype.

Improved D/TA and Information Fusion Based on HMM Indoor Localization

This paper describes an efficient Bayesian framework for localization based on Ultra-wide Bandwidth (UWB) system. Approximate grid-based method based on the Hidden Markov Model (HMM) is an effective method to estimate the position of the Moving Terminal (MT) with the mixed line-of-sight/non-line-of-sight (LOS/NLOS) situation. This article proposes an algorithm by modifying the Position Transition Probability (PTP) according to the practical dynamic model and uses the information fusion effectively. We compare the Maximum Likelihood (ML) estimation with Detection/Tracking Algorithm (D/TA) estimation and its improved algorithm by simulation, in which the localization to an identical trajectory has been tested. The results of the analysis show that the proposed method has better accuracy and stability.

Study on Interactional Characteristics of WT Wheelchair Robot with Stairs during Stair-Climbing Process

The characteristics of interaction between WT wheelchair robot and stair environments is analyzed and possible patterns of WT wheelchair robot during the stairs climbing are summarized, and then the criterion to determine the pattern of the wheelchair robot is proposed. STATEFLOW module in MATLAB is used to simulating the whole stair-climbing of WT wheelchair robot, and an entire analytical procedure about how to determine the pattern by using the simulation curves is given.

Robust Visual Tracking Using Particle Filtering on SL(3) Group

Considering the process of objects imaging in the camera is essentially the projection transformation process. The paper proposes a novel visual tracking method using particle filtering on SL(3) group to predict the changes of the target area boundaries of next moment, which is used for dynamic model. Meanwhile, covariance matrices are applied for observation model. Extensive experiments prove that the proposed method can realize stable and accurate tracking for object with significant geometric deformation, even for nonrigid objects.

Design of Greenhouse Monitoring System Based on Zigbee

To satisfy the requirement of the control parameters in greenhouse, this paper introduced the design scheme of monitoring and control system based on Zigbee due to its low-cost, simplicity and mobility. We designed the sensor node, control node and gateway node based on CC2430, described the design method of hardware circuit and the flow chart of software. By monitoring the environment factors in real time, such as illumination, temperature, humility and carbon dioxide, the spray system, ventilation fans and lighting lamps were automated controlled to satisfy crop growth requirement. The monitoring system is easy to expand and update, and the program interface is friendly to operate.

By the Ball Screw Drive a New Initiative Knee Joint Structure Design

Passive AKPs being currently in use do not respond to the needs of daily living activities of many amputees. For example, it is difficult to climb stairs with natural posture and to adjust the stiffness of the knee joint motion during the swing phase. Therefore this paper proposes the instantaneous center with variable rotating multiaxial knee, the multiaxial four league rod mechanism composition, have bionic similarity, involving active knee mechanism design and experiment. Artificial limb main part is through motor based on active control knee flexion knee actuator.This paper was designed by the ball screw electric a new initiative knee institutions.

Covariance Tracking Algorithm on Bilateral Filtering under Lie Group Structure

The existing object tracking method using covariance modeling is hard to reach the desired tracking performance when the deformation of moving target and illumination changes are drastic, we proposed a object tracking algorithm based on bilateral filtering. Firstly, the algorithm deals the image to be tracked with bilateral filtering, and extracts the needed features of filtered image to construct covariance matrix as tracking model. Secondly, under log-Euclidean Riemannian metric, we construct similarity measure for object covariance matrix and model updating strategy. Extensive experiments show that the proposed method has better adaptability for object deformation and illumination changes.

A New Robust Tracking Approach in NLOS Environments

In wireless sensor networks, NLOS propagation often enlarges the errors of position estimates when time-of-arrival (TOA) measurements are used. To mitigate the effects caused by NLOS propagation, herein, an EKF-based robust non-parametric approach is proposed. In this paper, we utilize the variable kernel method to obtain an approximate noise density function, which is inexpensively computational and then used to improve the mobile positioning accuracy. Note that the standard EKF often works well when NLOS error is adequately low. This property could also be used to improve the accuracy of mobile positioning. In the proposed algorithm, a hard decision is employed to choose the rational position estimate which may come from the non-parametric approach or the standard EKF. Numerical simulations show a significant improvement over the standard EKF.

Simulation and Experimental Study of the Direction Control Based on the Torque Compensation of a Snake Robot

Because the direction goals of the snake robot are different in applications, e.g. the target point and target path, the direction control of a snake robot is a challenging problem. We have proposed a control method, which is called passive creeping based on the energy balance. In this paper, the direction of the snake robot which is controlled by the passive creeping control method is discussed. A new direction control method which is based on the torque compensation is proposed. The direction control method set a universal direction goal for all the applications. The torque of the head joint which leads the locomotion direction is adjusted by the torque compensation. The compensated torque decreases the angle between the direction of the body axis and the expected direction by the exponential decay function. In simulation, the trajectory and the angle express the process of direction adjustment. The error analysis proves the validity and adaptability of the proposed direction control. Also the validity of the proposed method is proved by the experiment which is based on the virtual/physical mixed experimental system.