Rotatable Platform Research Articles

Non-contact measurement of insulating bearing coating thickness based on multi-sensor combination

A high-resolution and non-contact method for measuring the thickness of the insulating ceramic coating is proposed. The measurement system consists of a chromatic confocal sensor, eddy-current sensor, prism, mirror, and high-precision rotatable and liftable platform. The chromatic confocal sensor can obtain the distance from the outer surface of the insulating coating, and the eddy-current sensor can get the distance from the inner surface of the insulating coating. The coating thickness can be obtained from the two sensors’ data combination and calculation. The geometrical optical path is analyzed to study the effect of the prism and mirror on the confocal sensor. The eddy-current sensor is simulated by COMSOL software with electromagnetic theories to explore the relationship between its output response and the measured surface's curvature. The sensing parameters of the two sensors are calibrated and optimized through simulation and experimental validation. Measurement software is developed by Labview to display the coating thickness in real time and reveal its distribution by 3D surface reconstruction. The measuring system’s performance is tested by an insulating bearing with a 60 mm outer radius. The results show that the axial resolution of the measuring system is 0.1 μm, the repeatable linearity is less than 3 μm, the dynamic measuring linearity relative to the mean value of the coating’s thickness is less than 8 μm, the detection speed is about 50 points/min. It has the advantages of high precision, non-contact, quick speed, stability, and visual display.

In-situ alignment of 3D printed anisotropic hard magnets

Within this work, we demonstrate in-situ alignment of the easy axis single-crystal magnetic particles inside a polymer matrix using fused filament fabrication. Two different magnetic materials are investigated: (i) Strontium hexaferrite inside a PA6 matrix, fill grade: 49 vol% and (ii) Samarium iron nitride inside a PA12 matrix, fill grade: 44 vol%. In the presence of the external alignment field, the strontium hexaferrite particles inside the PA6 matrix can be well aligned with a ratio of remnant magnetization to saturation magnetization in an easy axis of 0.7. No significant alignment for samarium iron nitride could be achieved. The results show the feasibility to fabricate magnets with arbitrary and locally defined easy axis using fused filament fabrication since the permanent magnets (or alternatively an electromagnet) can be mounted on a rotatable platform.

Design and test of a laser lighting device for plant growth.

Aiming at the problems of high energy consumption, complex wiring, high layout cost, limited use environment, and limited function of conventional plant lighting equipment such as fluorescent lamps, sodium lamps, etc., this paper develops a type of laser device for plant growth with nanometer lasers based on the design of an intelligent control system of an immune algorithm, constant current driving circuit of the laser, pulse power supply, and rotatable intelligent platform to make the device more stable, reliable, practical, and energy efficient, and provides a useful reference for the innovation and application of materials, processes, and methods of plant lighting. The effects of nanometer laser light supplementation on the growth of purple lettuce, romaine lettuce, Chinese cabbage, and you-mai vegetable have been studied with the vegetables mentioned above as experimental materials and with natural light as the control sample. The results show that the nanometer laser device significantly increases stem height, stem thickness, leaf area, leaf number, and chlorophyll content, effectively promotes plant growth, and achieves efficient cultivation. In the future, studies of the effects of laser treatment on plant physiology and biochemistry will be sped up to explore the molecular biological mechanism of lasers to promote application and technological innovation of lasers in lighting for plant growth and the laser device in productivity.

A calibration method for rotary optical encoder temperature error in a rotational inertial navigation system

A rotary optical encoder is an important component in a rotational inertial navigation system (RINS). It is used to form a closed-loop motor control system and calculate the system attitude. The system performance will be affected by the encoder’s error. Ín addition to the installation errors, the working temperature variants can lead to encoder error. Therefore, in this paper we propose a method to calibrate and compensate the temperature errors of rotary optical encoders. First, an independent testing mechanism with position limitation and a rotatable platform is designed and produced to verify the temperature influence on encoders. Then, the temperature error of the rotary optical encoder used in RINS is calculated by a gyroscope whose sensitive axis is parallel to the same motor axis. The method is verified by a self-researched single-axis RINS. According to the experimental results, the measurement accuracy is increased by more than 47.9% compared to the traditional method.

Dynamic modeling and performance analysis of a lower-mobility parallel robot with a rotatable platform.

Recently, applications of high-speed, lightweight parallel robots have been gaining increasing interest. Studies have shown that their elastic that their elastic deformation during operation often affects the robot's dynamic performance. In this paper, we designed and studied a 3 DOF parallel robot with a rotatable working platform. We developed a rigid-flexible coupled dynamics model consisting of a fully flexible rod and a rigid platform by combining the Assumed Mode Method with the Augmented Lagrange Method. The driving moments under three different modes were used as feedforward in the model's numerical simulation and analysis. We conducted a comparative analysis demonstrating that the flexible rod's elastic deformation under a redundant drive is significantly smaller than that of a non-redundant one, leading to a better suppression effect on vibration. The system's dynamic performance under the redundant drive was significantly superior compared to that of the non-redundant one. Additionally, the motion accuracy was higher and the driving mode b was better than that of the driving mode c. Finally, the proposed dynamics model's correctness was verified by modeling it in Adams.

Simultaneous temperature and refractive index sensor based on an L-like Michelson interferometer.

We experimentally demonstrate, to the best of our knowledge, temperature and refractive index (RI) sensing with a novel L-like Michelson interferometer (MI). Two MIs are designed based on single-mode fiber (SMF) and multimode fiber (MMF), respectively, fabricated via an oxyhydrogen flame and a rotatable platform. By comparative experiments on the size and bent degree of the sensor, the corresponding parameters of the sensor with excellent performance are determined for measurement experiments. The RI sensitivity of the SMF L-like MI reaches -131.0nm/RIU, and the highest temperature sensitivity is 94.17 pm/°C. The highest RI of the MMF L-like MI is 176.5 nm/RIU, and the temperature sensitivity is 104.2 pm/°C. The L-like MI has advantages of low cost and easy fabrication, and is a promising temperature and RI sensor in a wide range of measurements.

Monitoring Cyanobacteria Bloom in Dianchi Lake Based on Ground-Based Multispectral Remote-Sensing Imaging: Preliminary Results

Some lakes in China have undergone serious eutrophication, with cyanobacterial blooms occurring frequently. Dynamic monitoring of cyanobacterial blooms is important. At present, the traditional lake-survey-based cyanobacterial bloom monitoring is spatiotemporally limited and requires considerable human and material resources. Although satellite remote sensing can rapidly monitor large-scale cyanobacterial blooms, clouds and other factors often mean that effective images cannot be obtained. It is also difficult to use this method to dynamically monitor and manage aquatic environments and provide early warnings of cyanobacterial blooms in lakes and reservoirs. In contrast, ground-based remote sensing can operate under cloud cover and thus act as a new technical method to dynamically monitor cyanobacterial blooms. In this study, ground-based remote-sensing technology was applied to multitemporal, multidirectional, and multiscene monitoring of cyanobacterial blooms in Dianchi Lake via an area array multispectral camera mounted on a rotatable cloud platform at a fixed station. Results indicate that ground-based imaging remote sensing can accurately reflect the spatiotemporal distribution characteristics of cyanobacterial blooms and provide timely and accurate data for salvage treatment and early warnings. Thus, ground-based multispectral remote-sensing data can operationalize the dynamic monitoring of cyanobacterial blooms. The methods and results from this study can provide references for monitoring such blooms in other lakes.

Development of Multi-Axis Crank Linkage Motion System for Synchronized Flight Simulation with VR Immersion

This paper developed a rotatable multi-axis motion platform combined with virtual reality (VR) immersion for flight simulation purposes. The system could simulate the state of the flight operation. The platform was mainly comprised of three crank linkage mechanisms to replace an expensive six degrees of freedom (DoF) Stewart platform. Then, an independent subsystem which could rotate ±180° was installed at the center of the platform. Therefore, this platform exhibited 4-DoF movement, such as heave, roll, pitch, and yaw. In the servo motor control unit, Visual Studio C# was applied as the software to establish a motion control system to interact with the motion controller and four sets of servo motors. Ethernet Control Automation Technology (EtherCAT) was utilized to communicate the commands and orders between a PC and each servo motor. The optimum controller parameters of this system were obtained using Simulink simulation and verified by experiment. The multiple sets of servo motors and crank linkage mechanisms were synchronized with flight VR imagery. For VR imagery, the software Unity was used to design the flying digital content. The controller was used to transmit the platform’s spatial information to meet the direction of the pilot commands and to compensate the direction of the deviation in spatial coordinates. To achieve synchronized response and motion with respect to the three crank linkage mechanism platform and VR imagery on the tester’s goggle view, the relation of the spatial coordinate of VR imagery and three crank linkage mechanisms was transformed to angular displacement, speed and acceleration which were used to command the motor drive system. As soon as the position of the VR imagery changed, the computer instantly synchronized the VR imagery information to the multi-axis platform and performed multi-axis dynamic motion synchronously according to its commanded information. The testers can thus immerse in the VR image environment by watching the VR content, and obtain a flying experience.

Development of the Soft X-ray AGM-AGS RIXS beamline at the Taiwan Photon Source.

We report on the development of a high-resolution and highly efficient beamline for soft X-ray resonant inelastic X-ray scattering (RIXS) located at the Taiwan Photon Source. This beamline adopts an optical design that uses an active grating monochromator (AGM) and an active grating spectrometer (AGS) to implement the energy compensation principle of grating dispersion. Active gratings are utilized to diminish defocus, coma and higher-order aberrations, as well as to decrease the slope errors caused by thermal deformation and optical polishing. The AGS is mounted on a rotatable granite platform to enable momentum-resolved RIXS measurements with scattering angles over a wide range. Several high-precision instruments developed in-house for this beamline are described briefly. The best energy resolution obtained from this AGM-AGS beamline was 12.4 meV at 530 eV, achieving a resolving power of 4.2× 104, while the bandwidth of the incident soft X-rays was kept at 0.5 eV. To demonstrate the scientific impact of high-resolution RIXS, we present an example of momentum-resolved RIXS measurements on a high-temperature superconducting cuprate, i.e. La2-xSrxCuO4. The measurements reveal the A1g buckling phonons in superconducting cuprates, opening a new opportunity to investigate the coupling between these phonons and charge-density waves.

Determination of the Friction Angle between the Wheat Ear and Stripper Fingers

Introduction. Determining the angle of friction between stripper fingers and a wheat ear is an important task aimed at finding the optimal design parameters and operating modes of stripping devices. When stripper fingers and wheat ears interact, the relative position of the ear glumes, flower glumes, and grains is densified. In this case, the spikelet surface roughness changes. Materials and Methods. A series of experiments was carried out to determine the angles of friction between a steel stripper fingers and wheat ears. Wheat varieties “Moskovskaya 40” and “Moskovskaya 56” were selected for the study. The experimental measuring installation is a frame with a rotatable platform mounted on it with the adjustable angle of rotation. The goniometer head provides the ability to fix the platform rotation angle value. The weight suspended from the stem of the plant imitated the forces arising in the process of stripping. The width and thickness of the wheat ear were also measured and recorded. Results. The influence of the size of the wheat ear on the angle of friction is determined. The results of the study are divided into two groups. The following values of the friction angles were obtained: 26.4–31.5° for the wheat with ear width of less than 10.4 mm; 22.0–27.1° for the wheat with ear width of more than 10.4 mm. Discussion and Conclusion. The angles of friction of wheat ears on the stripper fingers for wheat varieties specific to the Central region are obtained. The dependence of the angle of friction on the ratio of the geometric dimensions of the wheat ear and the slit width of the stripper fingers is established. When a wheat ear width is less than 10.4 mm, an effect of pinching the spikelets between the stripper fingers was observed. In this case, the coefficient of friction noticeably increased.

Dynamic Analysis of Semi-Circular Dry-Joint Masonry Arches: Small-Scale Experiment and Discrete Element Modeling

This study presents a numerical investigation of the dynamic behavior of dry-joint unreinforced semi-circular masonry arches using the discrete element method (DEM). Masonry arches are analyzed as a system of rigid blocks, mechanically interacting with each other through relative contact displacements. First, the applied modeling strategy is validated using a small-scale tilting experiment performed on a 3D printed arch model and a custom-made rotatable platform. Then, quasi-static and dynamic analysis analyses are performed on computational models to better understand the seismic capacity of the masonry arches depending on the frequency content of the excitations, thickness-to-radius ratios, scale of the arch, and the contact stiffness values. The results of the analyses reveal the capabilities of the discrete element models on the simulation of masonry arches. Particular findings include these types of arches’ vulnerability to excitations lower than 2 Hz dominant frequency. Furthermore, the impact of scale and slenderness become more pronounced for frequencies greater than 2 Hz. Finally, it is observed that once contact stiffness values are larger than 10 GPa/m, the effect of this parameter is negligible; but it should be carefully selected at lower values.

Performance of fast-ion loss diagnostic on EAST.

The scintillator-based detector for fast-ion loss measurements has been installed on EAST. To obtain high temporal resolution for fast-ion loss diagnostics, fast photomultiplier tube systems have been developed which can supply the complementary measurements to the previous image system with good energy and pitch resolution by using a CCD camera. By applying the rotatable platform, the prompt losses of beam-ions can be measured in normal and reverse magnetic field. The thick-target bremsstrahlung occurring in the stainless steel shield with energetic electrons can produce X-rays, which will strike on the scintillator based detector. To understand this interference on fast-ion loss signals, the effects of energetic electrons on the scintillator-based detector are studied, including runaway electrons in the plasma ramping-up phase and fast electrons accelerated by the lower hybrid wave.

A Novel 2R Parallel Mechanism for Alt-azimuth Pedestal

This paper presents a novel 2R parallel mechanism used as alt-azimuth pedestal, i.e. a 2-DOF (degree-of-freedom) pedestal for supporting and rotating equipment about two perpendicular axes. Its active joints are two sliders equipped with servo control on a circular rail. The synchronous and asynchronous motions of the two sliders lead to the azimuth (rotation about the vertical axis) and pitch (rotation about the horizontal axis) of the rotatable platform, respectively. The DOF computation and kinematics are dealt with firstly, and then the dynamic model of the 2R parallel mechanism is established by using the Lagrange equation. Eventually, a numerical simulation of the typical trajectory motion is carried out, and the actuating torque needed in the actuators for the trajectory tracking motion is worked out by employing the derived inverse dynamic equations, which is consistent with the result obtained from commercial software. This study lays a solid base for the further investigation and engineering implementation of the 2R parallel mechanism.

Development of test platform for evaluating disturbance characteristics of a lunar soil sampler

Lunar soil sampling technique is of great significant scientific and practical significance and hopefully improve the current situation of global energy shortage. Lunar soil sampler is one of the most important parts of drilling and coring system to collect lunar soil sample. The coring method in this paper has the advantages of high recovery rate, low power consumption, effectively keeping the sequence stratigraphy, etc. In this paper, a test platform for evaluating disturbance characteristics of a lunar soil sampler is proposed. The test platform is composition with drilling mechanism, core-pulling mechanism, position servo system of lunar soil simulant container, and rotatable platform, etc. The ground tests of drilling and sampling were carried out to analysis the disturbance state of the sample collected by the lunar soil sampler.

Three-dimensional indoor visible light positioning system with a single transmitter and a single tilted receiver

Recently, visible light positioning has gradually become a research hotspot in indoor environments. Based on a single transmitter and a single tilted optical receiver, a three-dimensional (3-D) indoor visible light positioning system is proposed. The tilted optical receiver is installed on a rotatable and retractable platform. The 3-D space is divided many two-dimensional (2-D) planes by lifting the platform of the optical receiver. In each 2-D plane, various azimuth angles can be obtained by rotating the receiver platform, which offers a feasible way to perform multiple measurements with different azimuth angles to achieve the angle gain. According to the difference of the angle gain, a 3-D positioning algorithm is proposed. Experimental results show that the proposed positioning algorithm can provide good positioning accuracy.

Innovative Project of Prototype Railway Wagon and Intermodal Transport System

A special wagon with a low rotatable loading platform for transportation of truck vehicles by rail was developed in Military University of Technology in the Department of Mechanics and Applied Computer Science in Warsaw. The essence of such reloading is to place the semitrailer on a special rotatable platform with the use of a truck tractor. The structure can be used for transportation of different types of vehicles such as tractors, trucks, trailers, semitrailers and cargo containers. The wagon allows quick and fast loading and unloading without any platform infrastructure or terminals. An intermodal transport system based on an innovative concept of the railway wagon, which will use the national railway infrastructure, was developed. The process of loading and unloading the trailers can be performed considering a whole train or individual wagons from any part of the train (no cranes needed). This type of railway wagon will allow transport companies to save time and money for road transport. The advantages of this construction are reduction of the negative impact on the environment as well as an increase of road safety by reducing the number of vehicles on the roads. As part of the work on the wagon and the intermodal transport system, a strength test of the wagon structure was carried out and the effort of the basic components of a the wagon and a complete structure was estimated. For this purpose, numerical analysis was used.

FE numerical tests of railway wagon for intermodal transport according to PN-EU standards

Abstract A special wagon, presented in the paper, can be used for intermodal transport of various types of vehicles. It enables transport of vehicles of 36 tons mass and height of 4m on the GB1 clearance height. An innovative wagon is equipped with a frame-support with marginal parts mounted on standard biaxial bogies and the central part lowered with a rotatable loading platform. The rotating part of wagon acts as a kind of platform, allowing truck to move through it during load/unload. During railway operation, this rotating platform is to become an integrated part of the wagon; the tailboards of the rotating part will be connected to the over-bogie part with the special locks. A unique concept of the wagon structure forced a design approach which was rather unusual for the rail industry. Since the design team aimed at very challenging demands of GB1 envelope and usage of standard bogies, the layout of the wagon had to be thoroughly examined in terms of its overall stiffness. Every major design change had to be simulated in order to accurately predict its influence on the whole wagon structure. FE analysis was used for numerical tests of such a wagon structure in different configurations. The calculations were carried out on the basis of PN-EN standards. Selected results of numerical tests of the prototype version of a such wagon for intermodal transports were presented in the paper.

Household Automatic Grain-Bagging Machine System

A small automatic grain-bagging machine system for household is presented on the basis of analyzing the demand for grain-bagging in household with more cultivated lands. The household automatic grain-bagging machine (HAGBM) is composed of grain conveyer device, opening and hanging bag device, automatic weighing measurement device, grain bagging device, sewing bag device and control system. Their structures are detailedly analyzed and 3D models are built up by Solidworks software. Control system has been discussed. It adopts PLC to control four motors and a weight sensor. The results indicate that four opening and hanging bag mechanisms installed on a rotatable platform complete four main processes of automatic grain-bagging. HAGBM suits automatic grain-bagging of households. It has small machine, high efficiency, and easy disassembling. It has more practical significance under lacking of young rural labor force.

A New Method to Control and Monitor a 6 D.O.F. Robot Arm

This paper mainly talks about the design of a controlling and monitoring system of the robot arm based on FPGA. The robot arm has 6 DOFs (Degree of Freedom). Every joint was driven by a servo motor. These servo motors were located as the finger, the wrist, the three arms and a rotatable platform. The FPGA programs were completed using the Verilog HDL. We programmed a LabVIEW VI to function as a controlling center. The data between PC and FPGA were transported through a ZigBee wireless network which consisted of 2 XBee devices and a wireless camera. They were used to monitor the moving condition of the arms. The experimental results show that the robot arms move with no apparent delay controlled by the host computer. The real-time display of the arm’s status is realized by the upper computer.

Self-cleaning in tree frog toe pads; a mechanism for recovering from contamination without the need for grooming

Tree frogs use adhesive toe pads for climbing on a variety of surfaces. They rely on wet adhesion, which is aided by the secretion of mucus. In nature, the pads will undoubtedly get contaminated regularly through usage, but appear to maintain their stickiness over time. Here, we show in two experiments that the toe pads of White's tree frogs (Litoria caerulea) quickly recover from contamination through a self-cleaning mechanism. We compared adhesive forces prior to and after contamination of (1) the whole animal on a rotatable platform and (2) individual toe pads in restrained frogs mimicking individual steps using a motorised stage. In both cases, the adhesive forces recovered after a few steps but this took significantly longer in single toe pad experiments from restrained frogs, showing that use of the pads increases recovery. We propose that both shear movements and a 'flushing' effect of the secreted mucus play an important role in shedding particles/contaminants.