Applied Mechanics and Materials Vol. 394

Abstract: Neural network self-learning optimization PID control algorithm is put forward for free-floating space robot with flexible manipulators. Firstly, dynamics model of space flexible robot is established, then, neural network with good learning ability is used to approach non-linear system. Optimization algorithm of network weights is designed to speed up the learning speed and the adjustment velocity. Error function is offered by PID controller. The neural network self-learning PID control method can improve the control precision.

Abstract: The single neutron adaptive PID controller is applied to the angular velocity tracking control of the hydraulic lifting system. The angle velocity tracking control strategy of the lifting process is proposed, and the lifting angle velocity is designed based on the sine acceleration function, and the lifting angle velocity dynamic programming based on the real-time angle is proposed. The single neutron adaptive PID control method is studied, and in order to improve its performance, a method utilizing genetic algorithm to optimize these parameters of single neuron PID controller is presented. The control algorithm is applied to the large mechanical lifting process successfully, and the simulation results show that the control performance of the Adaptive PSD Controller is more effective.

Abstract: A large variable speed constant frequency (VSCF) wind power system usually adopts the variable pitch control technology to ensure the output power is steady to ensure the safety of the wind power system above the rated wind speed. But the strong nonlinear and large moment of inertia of wind turbine result in the difficulty of variable pitch control, both simple fuzzy control and conventional PID control can not achieve a good control effect. Concerning this issue, variable pitch control algorithm is proposed based on self-tuning fuzzy adaptive PID control strategy. According to the dynamic model of VSCF, a simulation model of wind turbine control system is built in this paper with Matlab/Simulink. When the wind speed is random variable above the rated speed, the simulation results show that the proposed control strategy can keep the output power of the system around the rated power.

Abstract: Since fully automatic image segmentation on natural images is usually hard to provide guaranteed results, interactive scheme with a few simple user inputs becomes a good alternative. This paper presents a novel interactive method based on regional attacking and merging mechanism within a cellular automaton (CA) framework. With an attacking rule based on regions maximal similarity, the adjacent homogeneous regions that are initialized by pre-segmentation are automatically merged and labeled, the users only need to indicate the object and background regions with rough markers. The whole process neednt set any similarity threshold in advance and the desired contours are effectively extracted by labeling all the non-marker regions as either background or object. Extensive experiments are performed and the results show that the proposed scheme can reliably extract the object contours from the complex background.

Abstract: To meet the demands of the rotating structure for self-power, a novel gyromagnetic piezo-cantilever generator (GPCG) excited by the coupling between rotating magnets and those fixed on piezo-cantilever was presented. The influence of magnetic force (number and configuration of the magnets) and rotating speed on energy generation of the GPCG was investigated experimentally. The research results show that there are 9 optimal rotating speeds for the GPCG to achieve peak voltage at speed range of 0-1390r/min. With 1 magnet (ø12x2mm³) fixed on piezo-cantilever, the increasing number of rotating magnets (ø12x4mm³) in the same place (n_s) of the rotator exerts no influence on the optimal rotating speeds, but leads to rising output voltage. At 1042.5r/min, the achieved peak voltages from the GPCG in the case of n_s=1/2/4/6 are 13.2/16.6/23.8/27.8V respectively. The optimal speeds decrease and the peak voltage rises with the increasing number of magnets evenly distributed on the rotator (n_d). In the case of 1 magnet fixed on piezo-cantilever and n_d=1/2/4/8, the optimal rotating speeds and the peek voltages from the GPCG are 708.9/528.2/528.2/264.1r/min and 13.2/16.6/23.8/27.8V respectively.

Abstract: In this paper the spacecraft attitude stability problem with external disturbance are considered. A nonlinear attitude controller introducing disturbance suppression for spacecraft is designed using internal model principle. The effectiveness and robustness are demonstrated through a series of numerical simulations.

Abstract: This paper presents a methodology for the development of an UAV Autopilot System, based on modeling, instrumentation and a control law, with the purpose of stabilizing the airplane attitude. Firstly, were made experimental test flights by manual control for obtaining the longitudinal model parameters using the Matlab toolbox called "System Identification Tool". The model is represented by a transfer function of the pitch angle with respect to the elevator into an open-loop system. The system is stabilized using a PD controller (derivative-proportional) tuned with poles placement method. The zero exclusion principle is used to compute the robustness margin of the closed-loop system. Different experiments were made in order to validate theoretical results which are presented at the end of this work.

Abstract: The selection and design of the sensor is one of the key technologies for UHF PD detection. The UHF sensors popular used in PD detection and location in substation are partial discharge UHF sensor are usually ultra wideband antenna in the frequency range of 200 MHz to 1.5 GHz, which contains interference from communication signals. Accordingly, in order to improve the detection sensitivity and the signal-to-noise ratio, a kind of multi-band UHF narrowband sensor is proposed and designed in accordance with the principles of the loop antenna for PD detection. The proposed frequency resonant bands are set in the ranges of 480MHz-520MHz, 800MHz-850MHz and 1.1GHz-1.2GHz. The design based on simulation is finished and the performances of the prototype sensor are researched by parametric test and PD detection of three typical discharges: corona discharge, surface discharge and metallic particles discharge generated by PD mode. Results show that the selection of band for the UHF sensor is reasonable, and the sensor is with high sensitivity.

Abstract: We describe the development of teleoperated robotic cleaning systems for use in a highly radioactive zone of a hot-cell. As the hot-cell is active, direct access to the in-cell by human workers is not possible because of the nature of the high radioactivity of spent nuclear fuel. The teleoperated robotic cleaning systems were designed and developed to clean up or decontaminate a contaminated floor of the in-cell in a remote manner, thereby completely eliminating human interaction with hazardous radioactive contaminants. These robotic cleaning systems are classified into two systems depending on the task environment they are applied to - ROCCS (RObotic Contamination Collection System)-I and-II. We present the environmental, functional, mechanical design considerations, controls and capabilities of the developed teleoperated robotic cleaning systems.

Abstract: Learning from Demonstration (LfD) is a technique for teaching a system through demonstration. In areas like service robotics the robot should be user friendly in terms of coding, so LfD techniques will be of greater advantage in this domain. In this paper two novel approaches, counter based technique and encoder based technique is proposed for teaching a mobile service robot to navigate from one point to another with a novel state based obstacle avoidance technique. The main aim of the work is to develop an LfD Algorithm which is less complex in terms of hardware and software. Both the proposed methods along with obstacle avoidance have been implemented and tested using Player/Stage robotics simulator.