Experimental Validation and Updating of the Flexible Multibody Model of a Commercial 3R Planar Manipulator

2011 ◽  
Author(s):  
Stefano Fiorati ◽  
Emiliano Mucchi ◽  
Raffaele Di Gregorio ◽  
Giorgio Dalpiaz
Keyword(s):  
Ad Hoc ◽  
Low Frequency ◽  
Experimental Tests ◽  
Low Speed ◽  
Operational Conditions ◽  
Multibody Model ◽  
Planar Manipulators ◽  
Flexible Multibody ◽  
Modes Of Vibration ◽  
Synthesis Methodology

Serial planar manipulators are diffusely used either as stand-alone machines or as part of more complex cells, and many commercial planar manipulators are available on the market. These commercial machines are mainly destined to accomplish low-speed tasks, and they are designed by taking into account their flexibility at most in the joints. Unfortunately, there are particular installation conditions in which even low-speed tasks can generate low-frequency vibrations that highly interfere with the task. This aspect is highlighted here with reference to a commercial 3R planar manipulator, and how to manage this problem is explained. In this sight, a flexible multibody model is developed where the flexibility of the frame, the manipulator is fixed to, is modeled over the flexibility of the joints, that is introduced as lumped stiffness. In particular, the flexible frame is included in the model by using a Component Mode Synthesis methodology, in which only the natural modes of vibration and the static constrain modes are accounted. The model is validated through an experimental campaign. The experimental tests consist of several modal analyses, together with acceleration and laser Doppler measurements in operational conditions. This methodology allows to provide a model which takes into account the installation conditions, and gives a tool for studying ad-hoc solutions which prevent the occurrence of low-frequency vibrations.

Multibody modeling and vibration testing of 3R planar manipulators: effects of flexible installation frames

Robotica ◽  
2013 ◽  
Vol 31 (8) ◽  
pp. 1209-1220
Author(s):  
Emiliano Mucchi ◽  
Stefano Fiorati ◽  
Raffaele Di Gregorio ◽  
Giorgio Dalpiaz
Keyword(s):  
Ad Hoc ◽  
Low Frequency ◽  
Experimental Tests ◽  
Multibody Modeling ◽  
Low Speed ◽  
Operational Conditions ◽  
Multibody Model ◽  
Planar Manipulators ◽  
Flexible Multibody ◽  
Synthesis Methodology

SUMMARYThis work presents the experimental validation and updating of a flexible multibody model ideated for taking into account installation conditions of industrial serial planar manipulators without resorting to cumbersome modeling. The flexibility of the frame, the manipulator is fixed, is modeled over the flexibility of joints, which is introduced as lumped stiffness. In particular, the flexible frame is included in the model by using the Component Mode Synthesis methodology, in which only the natural modes of vibration and the static constrain modes are accounted. The flexible multibody model has been developed because these commercial machines are mainly used to perform low-speed tasks, and they are designed by taking into account their flexibility at most in the joints. Unfortunately, there are particular installation conditions in which even low-speed tasks can generate low-frequency vibrations that highly interfere with the task. This aspect is considered here, and how to manage this problem is explained by using the developed multibody model. The model is validated through experimental measurements. The experimental tests consist of several modal analyses, together with acceleration and laser Doppler measurements in operational conditions. This methodology takes into account the installation conditions through the model of flexible frame, and gives a tool for studying ad hoc solutions which prevent the occurrence of unwanted low-frequency vibrations.

scholarly journals A phase-locked loop using ESO-based loop filter for grid-connected converter: performance analysis

2021 ◽  
Author(s):  
Baoling Guo ◽  
Seddik Bacha ◽  
Mazen Alamir ◽  
Julien Pouget
Keyword(s):  
Performance Analysis ◽  
Frequency Domain ◽  
Low Frequency ◽  
Experimental Tests ◽  
Frequency Measurement ◽  
Phase Locked Loop ◽  
Frequency Domain Analysis ◽  
Loop Filter ◽  
Control Stability ◽  
Unbalanced Grid

AbstractAn extended state observer (ESO)-based loop filter is designed for the phase-locked loop (PLL) involved in a disturbed grid-connected converter (GcC). This ESO-based design enhances the performances and robustness of the PLL, and, therefore, improves control performances of the disturbed GcCs. Besides, the ESO-based LF can be applied to PLLs with extra filters for abnormal grid conditions. The unbalanced grid is particularly taken into account for the performance analysis. A tuning approach based on the well-designed PI controller is discussed, which results in a fair comparison with conventional PI-type PLLs. The frequency domain properties are quantitatively analysed with respect to the control stability and the noises rejection. The frequency domain analysis and simulation results suggest that the performances of the generated ESO-based controllers are comparable to those of the PI control at low frequency, while have better ability to attenuate high-frequency measurement noises. The phase margin decreases slightly, but remains acceptable. Finally, experimental tests are conducted with a hybrid power hardware-in-the-loop benchmark, in which balanced/unbalanced cases are both explored. The obtained results prove the effectiveness of ESO-based PLLs when applied to the disturbed GcC.

scholarly journals Accuracy Improvement of Stator Inductance Identification Method Based on Low-Frequency Current Injection for Three-Level NPC Inverter-Fed IM Drives in Locked-Rotor Standstill Condition

Electronics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 488
Author(s):  
Yerganat Khojakhan ◽  
Kyoung-Min Choo ◽  
Junsin Yi ◽  
Chung-Yuen Won
Keyword(s):  
Induction Motor ◽  
Low Frequency ◽  
Current Injection ◽  
Heavy Load ◽  
Injection Test ◽  
Low Speed ◽  
Injection Speed ◽  
Speed Test ◽  
Identification Method ◽  
Drive Systems

In this paper, a stator inductance identification process is proposed. The process is based on a three-level neutral-point-clamped (NPC) inverter-fed induction motor (IM) drive with a standstill condition. Previously, a low-speed alternating current (AC) injection test for stator inductance identification was proposed to overcome practical problems in conventional identification methods for three-level NPC inverter-based IM drives. However, the low-speed AC injection test-based identification method has some problems if a heavy load or mechanical brake is connected, as these can forcibly bring the rotor to a standstill during parameter identification. Since this low-speed testing-based identification assumes the motor torque is considerably lower in low-speed operations, some inaccuracy is inevitable in this kind of standstill condition. In this paper, the proposed current injection speed generator is based on the previously studied low-speed test-based stator inductance identification method, but the proposed approach gives more accurate estimates under the aforementioned standstill conditions. The proposed method regulates the speed for sinusoidal low-frequency AC injection on the basis of the instantaneous reactive and air-gap active power ratio. This proposed stator inductance identification method is more accurate than conventional fixed low-frequency AC signal injection identification method for three-level NPC inverter-fed IM drive systems with a locked-rotor standstill condition. The proposed method’s accuracy and reliability were verified by simulation and experiment using an 18.5 kW induction motor.

Asymptotic derivation of a refined equation for an elastic beam resting on a Winkler foundation

2021 ◽  
pp. 108128652110238
Author(s):  
Barış Erbaş ◽  
Julius Kaplunov ◽  
Isaac Elishakoff
Keyword(s):  
Ad Hoc ◽  
Moving Load ◽  
Low Frequency ◽  
Elastic Beam ◽  
Winkler Foundation ◽  
One Dimensional ◽  
Beam Equations ◽  
Dimensional Equation ◽  
Phase And Group Velocities ◽  
Group Velocities

A two-dimensional mixed problem for a thin elastic strip resting on a Winkler foundation is considered within the framework of plane stress setup. The relative stiffness of the foundation is supposed to be small to ensure low-frequency vibrations. Asymptotic analysis at a higher order results in a one-dimensional equation of bending motion refining numerous ad hoc developments starting from Timoshenko-type beam equations. Two-term expansions through the foundation stiffness are presented for phase and group velocities, as well as for the critical velocity of a moving load. In addition, the formula for the longitudinal displacements of the beam due to its transverse compression is derived.

scholarly journals Cancellation exponents and multifractal scaling laws in the solar wind magnetohydrodynamic turbulence

1996 ◽  
Vol 14 (8) ◽  
pp. 777-785 ◽  
Author(s):  
V. Carbone ◽  
R. Bruno
Keyword(s):  
Solar Wind ◽  
Velocity Field ◽  
Scaling Laws ◽  
Interplanetary Medium ◽  
Low Frequency ◽  
Scaling Exponent ◽  
Magnetohydrodynamic Turbulence ◽  
Low Speed ◽  
Multifractal Scaling

Abstract. Some signed measures in turbulence are found to be sign-singular, that is their sign reverses continuously on arbitrary finer scales with a reduction of the cancellation between positive and negative contributions. The strength of the singularity is characterized by a scaling exponent κ, the cancellation exponent. In the present study by using some turbulent samples of the velocity field obtained from spacecraft measurements in the interplanetary medium, we show that sign-singularity is present everywhere in low-frequency turbulent samples. The cancellation exponent can be related to the characteristic scaling laws of turbulence. Differences in the values of κ, calculated in both high- and low-speed streams, allow us to outline some physical differences in the samples with different velocities.

The Feature Extraction Method of Gear Magnetic Memory Signal

2013 ◽  
Vol 819 ◽  
pp. 206-211
Author(s):  
Yong Gang Xu ◽  
Zhi Cong Xie ◽  
Lin Li Cui ◽  
Jing Wang
Keyword(s):  
Gear Tooth ◽  
Low Frequency ◽  
Magnetic Memory ◽  
Magnetic Signal ◽  
Heavy Load ◽  
Low Speed ◽  
Feature Extraction Method ◽  
Test Technology ◽  
Time Scale Decomposition ◽  
Memory Signals

Magnetic memory test technology is a new nondestructive testing technique, which is able to detect of the stress concentration area and potential fault of low speed and heavy load gear. Because the magnetic memory signals are easy to be disturbed by various sources of noises, a new method based on the intrinsic time-scale decomposition (ITD) is proposed to achieve the extraction of magnetic memory signal. Firstly, the magnetic memory signals are decomposed into several proper rotation components (PRC) and a trend component by ITD. Then reconstruct the first four order PRCs to eliminate the low frequency cyclic composition of magnetic memory signal and magnetic noise. Finally, the magnetic signal strengths of each gear tooth root are extracted using cycle average and local statistic method. The results of Experiments show that the method is suitable to pick up effective ingredients of signal to extract signal feature and has important application value in potential fault diagnosis of low speed and heavy load gearbox.

scholarly journals Multibody model of fruit harvesting trucks: comparison with experimental data and rollover analysis

2018 ◽  
Vol 49 (2) ◽  
pp. 92-99 ◽  
Author(s):  
Stefano Melzi ◽  
Edoardo Sabbioni ◽  
Michele Vignati ◽  
Maurizio Cutini ◽  
Massimo Brambilla ◽  
...  
Keyword(s):  
Experimental Tests ◽  
Soil Stiffness ◽  
Safety Issues ◽  
Multibody Model ◽  
Centre Of Gravity ◽  
Rollover Risk ◽  
Speed Up ◽  
The Stability ◽  
Italian National Institute ◽  
Comparison With Experimental Data

Fruit harvesting trucks are used to easy and speed-up the work of agricultural operators. These vehicles are provided with a moving cargo bed, which can be raised up to 3 meters from the ground so that workers are closer to the plants top. Due to factors like height of centre of gravity and operation on soft and irregular soil, these vehicles present several safety issues. This research, carried out inside a project funded by INAIL (Italian National Institute for Insurance against Accidents at Work), analysed the stability of fruit harvesting trucks with particular focus on rollover risk. Experimental tests were carried out to characterise the response of these vehicles. Multibody models of two trucks were then developed and used to determine the rollover angle along a generic direction considering the effect of vehicle configuration and of tire-soil stiffness.

scholarly journals ByeLab: An Agricultural Mobile Robot Prototype for Proximal Sensing and Precision Farming

2017 ◽  
Author(s):  
Renato Vidoni ◽  
Raimondo Gallo ◽  
Gianluca Ristorto ◽  
Giovanni Carabin ◽  
Fabrizio Mazzetto ◽  
...  
Keyword(s):  
Health Status ◽  
Mobile Robot ◽  
Ad Hoc ◽  
Experimental Tests ◽  
Precision Farming ◽  
Controlled Environment ◽  
Mechatronic Systems ◽  
Proximal Sensing ◽  
Bionic Eye ◽  
Outdoor Environments

At today, available mechatronics technology allows exploiting smart and precise sensors as well as embedded and effective mechatronic systems for developing (semi-)autonomous robotic platforms able to both navigate in different outdoor environments and implementing Precision Farming techniques. In this work, the experimental outdoor assessment of the performance of a mobile robotic lab, the ByeLab — Bionic eYe Laboratory — is presented and discussed. The ByeLab, developed at the Faculty of Science and Technology of the Free University of Bolzano (I), has been conceived with the aim of creating a (semi-)autonomous robotic system able to sense and monitor the health status of orchards and vineyards. For assessing and measuring the shape and the volume of the canopy, LIDAR technology coupled with ad-hoc developed algorithms have been exploited. To validate the ByeLab different experimental tests have been carried out. In addition to the in-lab and structured environments experimental tests that allowed to tune the algorithms, in this work the assessment of its capabilities — in particular the sensoric system — has been made outdoor controlled environment tests.

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