Applied Mechanics and Materials Vols. 325-326

Abstract: This paper is basic on a new production small-scale mining road header. It researches the characters of the hydraulic system and mainly concerns on its constant power systems mathematical models, analysis of stability of working condition, the simulation and modulation using the software of AMESim.

Abstract: In the optimisation stage of the systems one of the more important step is the optimisation of the dynamic behavior of all elements with priority the elements what have the slow frequency, like motors. The paper try to show how will be possible to optimise very easily the dynamic behavior of elements and systems, using LabVIEW propre instrumentation and the application of the transfer functions and neural tnetwork theory. By appling the virtual LabVIEW instrumentation is possible to choose on-line the optimal values for each constructive and functional parameters of the elements and the systems to obtain one good dynamic answer: maximal acceleration without vibration, minimum answer time and maximal precision. The paper presents some of the more important used transfer functions in the assisted analyse of the elements and systems and some practical results of the assisted optimisation by using the neural network method. In the research were been used some different way to optimize the convergence process, for example: using one time- delay of the first and second output from the neural layers; using the recursive link and time- delay; using the bipolar sigmoid hyperbolic tangent sensitive function replacing the sigmoid simple sensitive function. By on-line simulation of the neural network was possible to know what will be the influences of all network parameters like the input data, weight, biases matrix, sensitive functions, closed loops and time- delay, to the gradient errors, in a convergence process. In the optimization research we used the minimization of the gradient error function between the output and the target.

Abstract: The paper purpose is to present some aspects regarding the control system of unmanned aerial vehicle - UAV, used for local observations, surveillance and monitoring of interest area or as a training target for anti-aircraft systems. The calculus methodology allows a numerical simulation of UAV evolution in bad atmospheric conditions by using a nonlinear model, as well as a linear one for obtaining the guidance command. The UAV model which will be presented has six DOF (degrees of freedom), and an autonomous control system. This theoretical development allows us to build the stability matrix, command matrix and the control matrix and finally to analyze the stability of autonomous UAV flight. A robust guidance system, based on Kalman filter will be evaluated for different fly conditions and the results will be presented. The flight parameters and guidance will be analyzed. The paper is inspired by national project SAMO (Autonomous Aerial Monitoring System for Interest Areas of Great Endurance). Keywords: UAV, Simulation, Control, Guidance, Endurance, Surveillance, Monitoring, Kalman filter

Abstract: The guidance system of the NERVA small space launcher is based on the six degrees-of-freedom information delivered by an inertial platform. Due to the main scope of the project sponsored by the Romanian Ministry of Education, Research, Youth and Sports to build a cost-effective space launcher, the inertial platform was built with extensive use of on-the-shelf, low cost inertial sensors and equipment. Concerns regarding the behavior and reliability of the sensing block were solved during the first flight experiment in June 2010, on-board the military, unguided drone missile RT-759-01 NERVA-1 and the results are described. The behavior of the electronics under the dynamical loads of the rocket flight, involving overloads of more than 20 g-s and the level of vibration during the real flight was the focus of the flight test, the first ever performed in Romania. The data were broadcast through a eight channel telemetry chain and received on the ground in two different locations for reliability enhancement. The data acquisition performed very well and supplied the basis for further development of the more accurate orbital injection guidance system of the NERVA launcher of small satellites in LEO.

Abstract: The quadrotor is starting to be considered a serious candidate for small and precise VTOL UAV missions. However, one important drawback is the insufficient payload capability. The current paper proposes the star-shaped octorotor as a solution. Its dynamic model is derived and a control mechanism for stabilization and trajectory tracking is designed and tested using numerical simulations. The approach proves to be feasible. Thus, the base for creating an autonomous octorotor UAV is established.

Abstract: Joint flexibility is the key factor during dynamic control of robot manipulator. Accurate dynamic model is the fundamental of manipulator system design, analysis and control. This paper adopts Lagrange method to accomplish two degrees freedom manipulator modeling, and then design Backstepping control law according to a single-link manipulator. For the above control law, the proof of the Lyapunov stability is given and simulations are done. The simulated result suggested that the static error is decreased.

Abstract: The difference between the attitude angle and the rotation angle will cause the modeling error of DTG. The accurate calculation model of azimuth is established according to the relationship between the attitude angle and rotation angle. The error between the accurate calculation model and the traditional model is analyzed by simulating. The simulation show that the modeling error is proportional to the tilt angle and the pitch angle, when the change of the tilt angle and the pitch angle is 1°, the max change of the modeling error will be 3.6701.

Abstract: Pico-satellite’s potential use is increasingly gaining nation’s recognition. Because of its small volume and light weight, it is necessary to develop the special deployer. The key technologies of Zhejiang University Pico-Satellite Deployer (ZDPSD) are, cutter unlocking the door, conical spring driving the pico-satellite, oriented rail restricting the direction and locking shaft fixing the door. In September 2010, the two pico-satellites were launched and deployed successfully at the predetermined orbit. The paper includes designing and analyzing of the moving system, mode analyzing of the deployer and the experiments on ground and in-orbit. The key process of the development is summarized, which can be regarded as reference for the further developing.

Abstract: In this paper, a novel 3-degree-of-freedom (DOF) parallel manipulator that can perform three rotations around the remote centre is presented. The theory of screws and reciprocal screws is employed for the analysis of the geometric conditions. In particular, using circular guide to instead of R joints, so that has the advantage of enabling continuous 360° revolute around Z-axis. The inverse kinematics of mechanism is given and the workspace has a good performance. To compare with the machine constructed with traditional joints, it has the advantage of high rigidity and precision.

Abstract: Modern cars are integrated with more and more electronic devices, controllers, sensors, actuators, bring more convenience, comfort and safety to the driver. Therefore, complex functions have much higher requirement on communication network, with higher speed, so accelerate new type of vehicle network application, such as FlexRay, Ethernet, and etc. Wireless connection could provide a convenient and flexible topology, transport protocol solution, also could resolve vehicle electronic limit. This paper proposes vehicle network system architecture based on communication, including three types of wireless application on the network, covering three major direction, intelligent terminal connection, wireless diagnostic, telematics and some solutions on the key points specific. Description in the paper is already built to specification, and integrated in the test samples of the related electric control system on the demo car.