Papers by Keyword: Turntable

Abstract: In this paper, analysis and design of an upper turntable of general vertical rocket rivet fixture are presented by employing the finite element methods and topology optimization design which are based on the variable density method, in order to reduce the mass and volume of the turntable of general vertical rocket rivet fixture and improve rivet precision. During the design the loadcase is considered: constant force and torque, which is simplified and closer to actual working conditions. From static analysis of the original turntable, a topology optimization model was set up. By using topology optimization calculations a new turntable model was built and the analysis of it using finite element methods was carried out. Comparison between the optimized model and original was conducted and the results show that the stiffness was remarkably improved, the stress was well-distributed and the displacement was reduced after optimization. For designing other complicated structures this method can also provide reference and guidance.

Abstract: Turntable is the main bearing component of truck crane, its structural-load-carrying capacity influences the operational capability directly. This paper adopts the HyperWorks software to make topology optimization for the turntable structure of QY70G truck crane, and carry out the finite element analysis and comparison for the models before and after optimization, which provides an effective method to improve the turntable structure of truck crane. Turntable is one of the important components of truck crane，it bears hoist boom、lifting、luffing mechanism and bob-weight and so on, it is the transfer center of truck crane when it works, the structure will directly affect the lifting performance of the machine. But, the rotary table structure design is affected by the vehicle shape size and installation and space layout. The traditional design method is based the experience of analogy to check by finite element software, it is difficult to get the design scheme which meets the requirements given above and own better strength and stiffness, it also have the disadvantages of long design cycle and large workload. This article is based on the finite element method and structural topology optimal idea, by means of HyperWorks-OptiStruct, makes finite element analysis for the turntable structure of certain QY70G truck crane, and carries on the structural topology in the condition of setted installation location and space, in order to obtain the ideal design plan.

Abstract: To simulate the real field environment far field, to obtain the best performance of the laser measurements of the turntable tracking system to be developed, can be locked by means of the tracking of the target, the turntable adjusting the rotational angular velocity tracking system size and rotation means, so as to simulate different motion state space moving target effect on the laser irradiation to test the performance targets to achieve the targeting system performance evaluation.

Abstract: The article considers the previously presented manipulating mechanism for positioning of a microphone during acoustical measurements in anechoic chamber. Usually the aims of acoustical measurements in anechoic chamber are: estimation of Sound Power Level of the noise source, measurement of directional characteristics of an electroacoustical transducer, measurement of the sound diffusion characteristic of a given structure and a measurement of Sound Pressure Level on a given measurement grid. The specific of that kind of measurements brings up the need of measurement microphone positioning in many points of the measurement space accordingly to relevant standards. In most cases during the tests it is necessary to position the microphone in certain points on the hemisphere. In such cases utilizing of typical microphone stands impedes the measurement and extends the time needed for the tests. The presented manipulation system for a measurement microphone allows positioning the microphone on the hemisphere around the tested object as required by the standards on the Sound Power Level measurement. Its construction is a simple, rigid form aiming at little effect on the acoustic field inside the chamber whereas the control system and the software are targeted at the maximal flexibility that allows not only standard testing but also scientific research in freely selected scenarios. Since its initial introduction the system has been extended by an additional axis that is used for rotating the microphone, which allows its positioning on the line that is coincident with the centre of rotation of the turntable. Such an extension eliminates the problem of use of the corrections of the directional characteristics of the microphone when measuring the sound signal. The microphone can be positioned directly towards the source of the sound. The article briefly reviews the mechanical construction of the positioning mechanism and focuses on the structure of the control section of the drive system constructed in the manipulator. The method for cooperation of actuators and the control system is presented. Also the description is given for the internal structure of the multi-level control circuits built in the applied drives. Finally the structure of the control application is presented.

Abstract: Aiming at the problem that traditional PID control algorithm is difficult to get ideal control effect, a PID control algorithm based on improved BP neural network is proposed to improve the performance of turntable system. According to the structure and characteristic of BP neural network, the construction of PID controller and the description of improved BP neural network algorithm are introduced at first. Then, on the basis of the least square method and neural network prediction model of controlled object, the weight adjustment algorithm of PID is improved by replacing the measured values of BP network with calculated forecast output. A mathematical model of turntable control system is established and simulated. Simulation results show that the improved BP neural network PID controller has good control performance, high tracking accuracy and strong system robustness, which can be better applied to turntable system.

Abstract: This article describes a research on two degrees of freedom turntable with large panel array, proposed an electric-driven method with self-locking function and modular structure mode. And we designed the large panel array two degrees of freedom turntable with 6m × 6m board. The pointing accuracy of the two-axis is 0.01°, azimuth and pitch angle are range to ± 20°, It’s wind resistance level is 8 and have many advantages such as long-term self-locking, safe, reliable, light weight and so on. This article focuses on the turntable’s driving principles and structures; finite element analysis shows that the structure we designed is reasonably practicable, safe and reliable.

Abstract: A new method is proposed to calibrate the installation errors of SINS. According to the method, the installation errors of the gyro and accelerometer can be calibrated simultaneously, which not depend on latitude, gravity, scale factor and earth's rotation rate. By the multi-position combinations, the installation errors of the gyro and accelerometer are modulated into the sine and cosine functions, which can be identified respectively based on the least squares. In order to verify the correctness of the theoretical analysis, the SINS is experimented by a three-axis turntable, and the installation errors of the gyro and accelerometer are identified respectively according to the proposed method. After the compensation of the installation error, the accuracy of the SINS is improved significantly.

Abstract: A turntable device that can work in spray rack is introduced in this paper. The device can drive the workpieces hanging in the turntable revolute and rotate. The 3d software has been used to design the modeling, and calculated the gear parameters according the requirements of turning, such as allowable stress. Finally the device can meet the technological requirements, automatic and stress. It also got a satisfying result at the application in practical production.

Abstract: The article presents the structural and geometric synthesis and mechanical parameter choice for a manipulation mechanism for measurement microphone positioning during acoustical tests in anechoic chamber. Usually the aims of acoustical measurements in anechoic chamber are: noise source Sound Power Level estimation, electroacoustical transducer directional characteristics measurement, sound diffusing characteristic of a structure measurement, measurement of Sound Pressure Level on a given measurement grid The specific of that kind of measurements brings up the need of measurement microphone positioning in many points of the measurement space accordingly to relevant standards. In most cases during the tests it is necessary to position the microphone in certain points on the hemisphere. In such cases utilizing of typical microphone stands impedes the measurement and extends the time needed for the tests. Those circumstances led to idea of measurement manipulator construction that would allow changing the microphone position during the measurement accordingly to a specified algorithm. The following assumptions for construction were taken: measurement microphone moves on the hemisphere with a maximal radius of 2 m, the weight of transported object (microphone or other) does not exceed 1 kg, positioning accuracy is 1 mm. Structural and geometric synthesis was made taking into account mounting conditions in anechoic chamber in Department of Mechanics and Vibroacoustics AGH-UST. There were several variants labored that fulfilled the assumptions. The choice of particular solution was made based on: • manipulator drives possible installation analysis with regard to their acoustical noise emission • structure stiffness analysis with regard to assumed positioning accuracy of the microphone Finally a modular construction of manipulator was chosen, which is composed of industrial turntable (built in the level of the wire netting) and two linear motion modules (long axis, short axis). That solution means that the device under test fixed on the turntable rotates in the range of 2π, and the measurement microphone moves on the track of one quarter of a circle. Specific angular position of the linear modules was chosen which allows minimal dimensions of linear modules. Simultaneously the control structure and the software part are developed. The usefulness of the manipulator will be definitely confirmed by a research that should evaluate the influence of the construction elements on the acoustical free field in an anechoic chamber.