Vertical Pendulum Research Articles

Design and Test of Disturbed Fertilizer Strip-Ejection Device with Vertical Pendulum Bar Based on Discrete Element Method

Fertilizer can improve the yield of crops per unit area, and uniform fertilizer discharge can improve the fertilizer utilization rate. Therefore, it is meaningful to improve the performance of fertilizer-discharge devices in order to improve the modernization level of crop field fertilizer management. To address the problems of operational smoothness, stability and poor uniformity of fertilizer discharge, and other difficult problems encountered with strip fertilizer-discharge devices, this study designs a disturbed fertilizer strip-discharge device with a vertical pendulum. The main factors affecting the performance of fertilizer discharge were the wedge angle of the push-disturbing main pendulum bar (PMPB), the inclination angle of the aided-stirring pendulum pick (APP), the flow gap of the pendulum bar (FGPB), and the operation frequency of the swing-rod combination (SRC). The discrete element method (DEM) was used to establish a simulation model of the fertilizer device to explore the influence of the main factors on the performance of fertilizer discharge, with the coefficient of variation (CV) of fertilizer discharge uniformity and fertilizer discharge accuracy (FDA) used as the evaluation indices. The results show that the factors affecting the CV of fertilizer discharge uniformity and FDA were, in order of priority, the operation frequency of the SRC, the FGPB, the wedge angle of the PMPB, and the inclination angle of the APP. The optimal parameters after rounding were as follows: the wedge angle of the PMPB was 45°, the inclination angle of the APP was 46°, the operation frequency of the SRC was 188 times/min, and the FGPB was 4.5 mm. At this point, the model predicted that the CV of fertilizer discharge uniformity would be 10.53%, and that the FDA would be 3.19%. Using the optimal parameters for bench test verification, it was found that the wedge angle of the PMPB was 45°, the inclination angle of the APP was 46°, the operation frequency of the SRC was 188 times/min, the FGPB was 4.5 mm, the CV of the uniformity of the fertilizer discharge was 11.06%, and the FDA was 3.51%. In the test, the fertilizer-discharge device was stable and had good adaptability to different fertilizers. The results of this study can provide a theoretical reference for the development of precision strip-fertilizer application devices.

Design of A High-Precision Component-Type Vertical Pendulum Tiltmeter Based on FPGA.

This paper presents a high-precision component-type vertical pendulum tiltmeter based on an FPGA (Field Programmable Gate Array) that improves the utility and reliability of geophysical field tilt observation instruments. The system is designed for rapid deployment and offers flexible and efficient adaptability. It comprises a pendulum body, a triangular platform, a locking motor and sealing cover, a ratiometric measurement bridge, a high-speed ADC, and an FPGA embedded system. The pendulum body is a plumb-bob-type single-suspension wire vertical pendulum capable of measuring ground tilt in two orthogonal directions simultaneously. It is installed on a triangular platform, sealed as a whole, and equipped with a locking motor to withstand a free-fall impact of 2 m. The system utilizes a differential capacitance ratio bridge in the measurement circuit, replacing analog circuits with high-speed AD sampling and FPGA digital signal processing technology. This approach reduces hardware expenses and interferences from active devices. The system also features online compilation functionality for flexible measurement parameter settings, high reliability, ease of use, and rapid deployment without the need for professional technical personnel. The proposed tiltmeter holds significant importance for further research in geophysics.

System analysis and experimental investigation of a pendulum-based wave energy converter

Global economic development and environmental protection requirements are increasing the demand for renewable energy rapidly. Wave energy converters are a hotspot in research, and many designs have been proposed. Pendulum-based wave energy converters, because of their sealed structure and high reliability, are drawing researchers' attention. This article considers the concept of a Vertical Axis Parametric Pendulum Wave Energy Converter (VAPPWEC) and focuses mainly on the characteristics of the pendulum system. The dynamic function of the pendulum is proposed. A new evaluation indicator, Cumulative Frequency curves of Angular Velocity (CFAV) is introduced to analyze pendulum motion accurately and evaluate the harvesting performance conveniently. The model test shows the parametric resonance zone of the pendulum with a notable boundary and the pendulum's stability under power take-off (PTO) damping. Additionally, a large-range analysis method based on the Prescribed Excitation Model (PEM) is proposed, and the output power is assessed. Linear damping performs better than constant damping, with a maximum capture width ratio of 39.05%.

Model dan Kendali Modular pada Pendulum Terbalik tipe Rotary

Rotary Inverted Pendulum (RIP) is a physical system that is often used as a theoretical platform and application of non-linear, unstable, and underactuated control systems so that it poses a challenge to design controls and realize them. The mechanical construction of the system consists of a pendulum arm that rotates horizontally on the RIP base shaft and a vertical pendulum arm that swings from a downward position to an upright equilibrium position. This paper presents a model and control scheme for RIP in a modular manner, in which three controller sections are constructed and realized using Multibody Matlab. The three controller parts include: a swing-up using a positive feedback Proportional Derivative controller, a switching mode controller that works to change swing up control scheme into stabilization control when the vertical pendulum arm reaches a position around its upright equilibrium, and stabilization controller to maintain vertical arm balanced using a Proportional Derivative controller. The trajectory of the motion of the pendulum arm and the 3D visualization of the pendulum system presented using Multibody Matlab show the effectiveness of the applied method.

On the issue of the motion of balls in a double pendulum

The paper considers a model of a vertical double pendulum with one suspension centre moving in a vertical plane. For the proposed system of pendulums, differential equations of motion and conditions for the collision of balls are obtained. When modelling the movement of pendulums, the central impact of the balls was considered for various variants of the movement of the suspension point: the suspension point oscillates in the vertical direction; the suspension point makes rotational movements in the vertical plane. In this case, various conditions of the central impact between the balls were considered: absolutely inelastic impact; absolutely elastic impact; impact with the transformation of impact energy (elastic impact). Comparison of the results of the numerical simulation and the results of experiments with the Kapitza pendulum in published sources confirmed the possibility of modelling an elastic impact between balls in a double pendulum and between balls in an autobalancer with a horizontal axis of rotation of the rotor.

Correlation between the tilt anomaly on the vertical pendulum at the Songpan station and the 2021 MS7.4 Maduo earthquake in Qinghai province, China

Understanding the relationship between precursory deformation anomalies and strong earthquakes is vital for physical earthquake prediction. Six months before the 2021 MS7.4 Maduo earthquake in Qinghai province, China, the vertical pendulum at the Songpan station was observed to tilt southward with a high rate and large amplitude. Studies conducted before the 2021 MS7.4 Maduo earthquake inferred the tilt anomaly to be an earthquake precursor. However, after the earthquake, the relation between the earthquake and the anomaly became controversial, partly because the Songpan station is located at a great distance from the epicenter. In this study, based on the deformation anomaly characteristics, relationship between the seismogenic fault and the fault near the anomaly, and associated quantitative analyses, we concluded that this anomaly may be associated with the 2021 MS7.4 Maduo earthquake. The duration and amplitude of this anomaly matched with the magnitude and epicenter distance of the Maduo earthquake. We have also interpreted the reason why the anomaly occurred near a fault that is obliquely intersected with the seismogenic fault and why the anomaly is located far from the earthquake epicenter.

On the Issue of Collision of Balls in an Auto-Balancing Device

Abstract The paper considers a model of a vertical double pendulum, which includes two balls suspended on rigid non-deformable threads to one centre of the suspension. For the proposed system of pendulums, differential equations of motion and conditions for collision of balls have been recorded. When simulating the motion of the pendulums, the central collision of the balls has been considered for various options of the motion of the suspension point: the suspension point is motionless; the suspension point oscillates in the vertical direction; the suspension point makes rotational motions in the vertical plane. Meanwhile, various conditions for the central collision between the balls have been considered: a perfectly inelastic collision; a perfectly elastic collision; a collision with transformation of collision energy (partially elastic collision). The results of numerical simulation are consistent with the behaviour of pendulums in real physical models, which makes it possible to simulate an elastic collision between balls when studying their acceleration in auto-balancing devices.

Design of Ocean Wave Power Plant with a Two-Axis Vertical Pendulum Mechanism System

Renewable energy is a promising potential for the future, where this energy is low emission and environment friendly. One of the renewable energies that are abundant and rarely used is ocean waves. Energy from ocean waves can be extracted using an ocean wave power plant with a pendulum system (PLTGL-SB). The main components of PLTGL-SB are pontoon and pendulum, where the pendulum will oscillate when ocean waves hit the pontoon. This research will analyze PLTGL-SB with a two-axis mechanism. The analyzes were performed with simulations using CFD applications (computational fluid dynamics) and only used three degrees of freedom (pitching, rolling, and heaving). The design of PLTGL-SB has a length of 2.2 m, a width of 1.3 m, a height of 1.61 m, and an overall mass of 199.5 kg with two axes and two pendulums on each axis. The highest simulation results obtained a maximum deviation angle of 32.31° and an angular velocity of 1.44 rad/s with 10 kg pendulum mass and 1.0 m pendulum length at 0.5 m wave amplitude. If this design is used in the rumah apung Bangsring, it will require seven modules of PLTGL-SB and two additional 12V 50Ah batteries.

Energy regulation for a torque-driven vertical inertia wheel pendulum

The energy regulation of a torque–driven vertical inertia wheel pendulum is addressed in this paper, which allows to achieve an oscillatory motion of the non actuated pendulum around its upright position through the proper motion of the actuated inertia wheel. The contribution of the present paper is an energy regulator capable of inducing oscillations of the pendulum with a user specified desired amplitude. More precisely, the proposed controller achieves locally asymptotically an oscillatory motion of pendulum around its upright position, in which its amplitude can be specified within an interval. Simulation and experimental results on a torque–driven inertia wheel pendulum illustrate the performance of the proposed controller.

Tilt Active Vibration Isolation Using Vertical Pendulum and Piezoelectric Transducer with Parallel Controller

Tilt vibrations inevitably have negative effects on some precise engineering even after applying horizontal and vertical vibration isolations. It is difficult to adopt a traditional passive vibration isolation (PVI) scheme to realize tilt vibration isolation. In this paper, we present and develop a tilt active vibration isolation (AVI) device using a vertical pendulum (VP) tiltmeter and a piezoelectric transducer (PZT). The potential resolution of the VP is dependent on the mechanical thermal noise in the frequency bandwidth of about 0.0265 nrad, which need not be considered because it is far below the ground tilt of the laboratory. The tilt sensitivity of the device in an open-loop mode, investigated experimentally using a voltage controller, is found to be (1.63±0.11)×105 V/rad. To compensate for the hysteresis nonlinearity of the PZT, we experimentally established the multi-loop mathematical model of hysteresis, and designed a parallel controller consisting of both a hysteresis inverse model predictor and a digital proportional–integral–differential (PID) adjuster. Finally, the response of the device working in close-loop mode to the tilt vibration was tested experimentally, and the tilt AVI device showed a good vibration isolation performance, which can remarkably reduce the tilt vibration, for example, from 6.0131 μrad to below 0.0103 μrad.

Comment on “Dynamic Tilt Correction Using Direct Rotational Motion Measurements” by Felix Bernauer, Joachim Wassermann, and Heiner Igel

AbstractThis article identifies deficiencies in the article of Bernauer et al. (2020) in performing and describing shake table and numerical (synthetic) testing of newly designed seismic instruments for recording complex translational and rotational motion. In my opinion, this is a result from a deficiency in referencing previously published peer-reviewed papers in this area. I also disagree with Bernauer et al. (2020) interpretation of the origin of errors in a vertical sensor’s recording because the sensitivity of a vertical pendulum type sensor to small tilts is much lower than that of the horizontal. Complete differential equations of pendulum-type horizontal and vertical seismometers are presented and examples of previously performed numerical and shake table tests of seismic instruments are shown.

Nonlinear stress wave generation model as an earthquake precursor

A network of vertical static pendulums (tiltmeters) has been in operation in Central Europe since July 2007. Hundred and eighty three seismic events of magnitude 7 and greater have occurred worldwide (EMSC) during the ten-year period. Several kinds of tilt anomalies were recognised within days up to months before the mainshocks. The most typical anomaly was a sudden tilting, parallel with the geologic structure, where the pendulum was installed. Based on the observations, we are proposing an asperity model, explaining the generation of so called “stress waves” before the mainshocks. Such stress waves of very low frequency (i.e. periods of days up to the first months) could be detected anywhere on the globe, especially on active geological structures, parallel with the fault, where a mainshock can happen. The observations suggest that we could estimate that part of the global fault system, which generates the detected stress wave, and which reaches the critical state. The estimation can be performed according to the amplitude of the stress wave, compared with stress waves detected on other structures of different orientations. According to the length of the stress wave (its period) and the tilt amplitude, it could be possible to estimate the magnitude of the mainshock.

Load calculation and effect of deformation observation around Mudanjiang seismic station

With the acceleration of urbanization, the impact of human production and life on the earthquake observation environment is increasingly prominent. In order to study the influence of the construction of buildings (structures) around the observation station on the geophysical observation data, taking the deformation observation vertical pendulum tiltmeter and cavern strain gauge of Mudanjiang Seismic Station as examples, through field verification, inspection of instrument and equipment working state, environmental interference and meteorological factors, it was found that the construction time and direction of the southeast residential area of the observation station were related to the abnormal characteristics. In this study, based on the principle of superposition of normal concentrated force point load on the surface of semi-infinite body, the load change caused by the construction of station surrounding engineering was quantitatively calculated, and the influence degree of load was analyzed, which would provide support for further clarifying the interference source.

The background noise level of vertical pendulum tiltmeter in China

By using the observation data of the vertical pendulum tiltmeter in China, the influence of different sampling rates on the results of power spectral density is studied, and the background noise level of the seismic frequency band (200–600 s) of different stations and different types of instruments is emphatically analyzed. The conclusions are as follows: 1. The results of both single station and national statistics show that the noise levels of the two types of pendulum tiltmeter equal in the seismic frequency band; 2. There is no obvious regularity in the regional distribution, due to the influence of ocean and active tectonic movement, the noise levels of some stations in coastal areas are relatively high; 3. The curves of high noise level instrument are generally not smooth and burr-prone. Except for some stations affected by the ocean, they are mostly caused by the observation environment or the instrument itself.

Portable vertical pendulum tiltmeter development and application test

The paper presents the design idea of the portable vertical pendulum tiltmeter, based on in-depth understanding of the application situation of existing VP vertical pendulum tiltmeter in the field of precursory observation, in order to further broaden the scope of application and tap its market potential. A high precision capacitance micrometer was redesigned, at the same time, it also has an improved high reliability lock pendulum mechanism, automatic zeroing devices and Integrated low power circuit system, these designs make the vertical pendulum tiltmeter portable, but also has high reliability and stability. The portable vertical pendulum tiltmeter can be used for in situ observation with VP vertical pendulum tiltmeter in existing stations. It can be used for regular checking and troubleshooting of existing tiltmeters, and also can solve the problem of data loss during the maintenance of the tiltmeters. Through the experiments, the test results show that the portable vertical pendulum tiltmeter can record earth tide curve, the various performance index have reached or close to the expected design goals.

Development of synthetic methodology of neuro-fuzzy controller adjusted by genetic algorithm

The paper focuses on a synthetic methodology of a neuro-fuzzy controller adjusted by genetic algorithm for a dynamic control object. An algorithm for controller synthesis and a genetic algorithm for adjusting the controller's parameters have been developed. The methodology has been tested on the classical problem of stabilizing a vertical pendulum on a mobile trolley. The results obtained confirm the efficiency of the methodology and allow for the conclusion that the neuro-fuzzy controller when appropriately adjusted ensures high quality of the stabilization system, even if there are random disturbances on the dynamic object

Study of oscillatory motion using smartphones and tracker software

The purpose of this contribution is to propose a workshop for acquiring data through the use of a smartphone, not necessarily high end, equipped with a camera and the required application installed. With a smartphone and the free Physics Toolbox application, it is possible to study the oscillatory motion of both simple and vertical pendulums. This is possible by measuring the components of acceleration on the three axes by means of a reading from the internal accelerometers of the smartphone. The vertical motion of the pendulum brings to light the concept of elasticity. Thanks to the Tracker software it is possible to study the damped oscillatory motion of a moving body on a semi-circular drive through the video analysis of the motion itself. Tracker is a free video analysis and modelling tool built on the Open Source Physics Java framework. Given the simplicity of the acquisition procedure and data analysis it is possible to study the motion of circular bodies of different sizes and materials in a short amount of time. The activity relating the vertical motion of the pendulum study also allows for the comparison between the classical procedure, using a stopwatch and both proposals procedures, using smartphones and Tracker. The analysis of subsequent data acquisition must be carried out using standard spreadsheet calculations by introducing the concept of error and the techniques to make it as small as possible. The use of the new widespread technologies allows students to approach the physical concepts even outside of a classic laboratory. The ease of use and low cost allow any school environment to propose activities to the entire class by offering more contemporary workstations and organizing groups of a few students.

Analysis of a Single Vertical Pendulum Mechanism on the Pontoon-Boat as a Wave Energy Harvester

The aims of this study are to model the wave energy harvester device using a single pendulum on a pontoon called Single Vertical Pendulum Mechanism (SVPM) and analyze the voltage generated by the mechanism. The simulation method was conducted in order to provide the power generated by SVPM. The SVPM’s dimension was designed on a laboratory scale and the wave amplitude was adjusted by the amplitude on the laboratory pool. The mechanism model uses wave energy as the excitation force of the pendulum. The pendulum oscillates and drives the transmission gear which transmits the force to the generator. The generator produces electrical energy. The variation used in the simulation was the mass of the pendulum, the length of the pendulum’s arm, and the wave amplitude. The maximum power that can be generated by SVPM was 5,735 Watt occurred when the arrangement of SVPM was using the pendulum mass of 0,75 kg and the pendulum length of 0,2 m. The parameter that most affect the generated power of SVPM was the wave amplitude.

Detection of Earth's free oscillation excited by the Japan Mw9.0 Earthquake using different tiltmeter and strainmeter

The observatory network of the Crustal Deformation China Seismological Bureau was equipped with vertical pendulum tiltmeter, borehole tiltmeter, tunnel extension meters, multi-component borehole strainmeter, body strainmeter and other tilt and strain observation instruments. All of these instruments have recorded the Earth's free oscillation excited by the Japan Mw9.0 Earthquake. By analyzing those observations, all of the spheroidal oscillation modes (0S3—0S30) and toroidal oscillation modes (0T3—0T20) excited by the Japan Mw9.0 Earthquake were detected in this paper. In addition, comparing the different observation results which obtained by those instruments, we revealed their capacity to observe different kinds of oscillation and different frequency band modes, and analyzed report the reason. We found that the body strainmeter and the vertical pendulum tiltmeter have better observing results for spheroidal oscillation. Because of high noise in low frequency band, the borehole tiltmeter cannot observe the low-order spheroidal oscillation. In terms of observing the toroidal oscillation, the multi-component borehole strainmeter got a best result. The vertical pendulum tiltmeter observes a few toroidal oscillation modes, and the tunnel extension meters can only observe some low-order modes.

Relationship of Stress Changes and Anomalies in OLR Data of the Wenchuan and Lushan Earthquakes

The Longmenshan fault zone in southwest China has produced two large earthquakes within the last few years: the Wenchuan earthquake with magnitude scale (Ms) 8.0 on May 12, 2008, and the Lushan earthquake with Ms 7.0 on April 20, 2013. In this paper, we investigate the Coulomb stress changes, the data from the strainmeters and pendulum tiltmeter which detected stress changes before the Wenchuan and Lushan earthquakes, and the anomalies in the outgoing longwave radiation (OLR) data observed by National Oceanic and Atmospheric Administration Satellites. We do this using our proposed new change detection method, tested through examination of ten strong earthquakes in China, which can effectively reveal changes in OLR data before and after earthquakes. Our investigation suggests that the positive coseismic Coulomb stresses of Wenchuan may have increased the probability of the earthquake occurring. The pre-earthquake synchronous increments in stresses detected by strainmeters and the pendulum tiltmeter in several seconds can be viewed as slow earthquakes and thus may have triggered the Wenchuan and Lushan earthquakes. Our study indicates that there are larger OLR anomalies in fault zones than nonfault zones and those larger anomalies were generated before the Wenchuan than Lushan earthquakes. There were also larger increments in vertical pendulum tiltmeter and four-component borehole strains before the Wenchuan earthquake than before the Lushan earthquake. Our results suggest that larger stress changes may trigger larger earthquakes and cause larger anomalies in OLR data.