F. Sun

Actuator Nonlinearities Compensation Using RBF Neural Networks in Robot Control System

In this paper, a compensation scheme is presented for general actuator nonlinearities. The compensator uses two neural networks, one to estimate the unknown actuator nonlinearities and another to provide adaptive compensation in the feedforward path. Since radial basis function network has the universal approximation property and can avoid the local minima problem, the compensator uses RBF neural networks to estimate the actuator nonlinearities and eliminate their effects. GL matrix and operator are introduced to help prove the stability of the system. Rigorous proofs of closed-loop stability for the compensator are provided and yield turning algorithms for the weights of the RBF neural networks. The whole scheme provides a general procedure for using RBF neural networks to compensate the actuator nonlinearities in robot control system. Simulation results verify the effectiveness of the designed scheme and the theoretical discussion.

Global Sliding Mode Control with Adaptive Fuzzy Chattering Free Method for Nonlinear System

A novel fuzzy global sliding mode control (FGSMC) scheme is proposed for position tracking of a class of second-order nonlinear uncertain system. In the proposed scheme, we integrate input-output linearization technique to cancel the nonlinearities. By designing global sliding mode surface, the proposed scheme eliminates reaching phase problem so that the closed-loop system always shows invariance property to parameter uncertainties. Fuzzy logic systems are used to approximate the unknown system functions and switch item. Robust adaptive law is proposed to reduce approximation errors between true nonlinear functions and fuzzy systems, thus chattering phenomenon can be eliminated. Stability of the proposed control scheme is proved and the scheme is applied to an inverted pendulum system. Simulation studies are provided to confirm performance and effectiveness of the proposed control approach

A Hierarchical and Distributed QoS Routing Protocol for Two-layered Satellite Networks

The rapid development of onboard processing (OBP) pushes broadband satellite networks to carry on multimedia traffic. However, the function of onboard routing cannot be provided entirely in existing satellite networks with inter-satellite links (ISLs), and QoS of satellite networks cannot be reliably guaranteed because of great difficulties in processing of QoS services. In this paper, a two-layered low earth orbit (LEO) and medium earth orbit (MEO) satellite network (LMSN) is presented. Based on the idea of time-slot division, a novel dynamic hierarchical and distributed QoS routing protocol (HDRP) is investigated, and an adaptive bandwidth-constrained minimum-delay path (BMDP) algorithm is developed to calculate routing tables efficiently using the QoS metric information composed of delays and bandwidth. The performance of the LMSN and HDRP is also evaluated through simulations and theoretical analysis

The intelligent grasping tactics of dexterous hand

In the task of grasping objects with robotic hand, power grasp, also called whole hand grasp, is usually adopted. However, power grasp may incur severe target object deformation. To address this issue, a hybrid control algorithm is proposed, which could control dexterous robotic hand at different stages. When robotic hand does not contact target object, the speed of the fingers increases sharply under the position control law, guaranteeing the rapidness of the system. During the close contact process, the features of tactile data are analyzed and matrix models that corresponds to different types of objects are set up; and then corresponding integral separation PID control law is designed meticulously. The proposed method is verified by the experiment platform, showing a promising performance.

Vehicle Detection Based on Hypothesis and Verification of Objects

A novel method to detect vehicles is presented in the paper. Firstly, hypothesis of the vehicle is formed according to the geometrical features of the rear of the vehicle by the statistical histogram. Secondly, hypothesis is verified by the property of the shadow cast by the car according to a prior acknowledgement of traffic scene. Lastly, the vehicle detection is realized by hypothesis and verification of objects. The experimental results show the efficiency and feasibility of the method.

Decoupling Control of the Two-link Flexible Manipulator

To compensate for the coupling force between the joints of the two-link manipulator, using the tip deflection measured by an optical measurement device with position sensitive detectors (PSD), a decoupling controller based on the cloud model is presented in this paper. In the proposed control strategy, the control experience qualitatively expressed by linguistic is transformed into the control rulers through linguistic atoms and cloud models with normal representation. The Experiment studies on the test-bed of a two-link flexible manipulator are carried out to show the capability and effectiveness of the proposed approach.