Research of the Influence of Road Excitation on Human Body Comfort under the Harvester Working Condition

2019 ◽  
Vol 35 (4) ◽  
pp. 495-502
Author(s):  
Wei Jiang ◽  
Jie Zhou ◽  
Hongmei Xu ◽  
Shuang Liu ◽  
Chenglong Wang ◽  
...  
Keyword(s):  
Root Mean Square ◽  
Human Body ◽  
Surface Hardness ◽  
Low Frequency ◽  
Road Surface ◽  
Mean Square ◽  
Low Frequency Vibration ◽  
Road Excitation ◽  
Combine Harvester ◽  
Road Surface Roughness

Abstract. When the harvester travels in the field, road excitation will cause low-frequency vibration within 3 Hz, which is the most sensitive frequency range of human body. In order to evaluate the influence of road excitation on the comfort feelings of the harvester driver, vibration acceleration data were collected when the combine harvester was travelling at high and low speeds on flat-soft road, flat-solid road, and rough-solid road. The vibration comfort of the harvester was evaluated by root mean square (RMS) of weighted acceleration. The results showed that the speed of harvester, road surface roughness and hardness have great effects on harvester vibration comfort. Soft road has an obvious absorption effect on the vibration at 70 Hz. The increase in the speed of harvester and road surface hardness and roughness elevates the subjective discomfort of the driver. Keywords: Combine harvester, Comfort research, Road excitation, Root mean square of weighted acceleration, Vibration test.

scholarly journals Improving Low Frequency Isolation Performance of Optical Platforms Using Electromagnetic Active-Negative-Stiffness Method

2020 ◽  
Vol 10 (20) ◽  
pp. 7342
Author(s):  
Yamin Zhao ◽  
Junning Cui ◽  
Junchao Zhao ◽  
Xingyuan Bian ◽  
Limin Zou
Keyword(s):  
Root Mean Square ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Laser Interferometry ◽  
Relative Displacement ◽  
Negative Stiffness ◽  
Mean Square ◽  
Electromagnetic Actuators ◽  
Micro Vibration ◽  
Isolation Performance

To improve the low-frequency isolation performance of optical platforms, an electromagnetic active-negative-stiffness generator (EANSG) was proposed, using nano-resolution laser interferometry sensors to monitor the micro-vibration of an optical platform, and precision electromagnetic actuators integrated with a relative displacement feedback strategy to counteract the positive stiffness of pneumatic springs within a micro-vibration stroke, thereby producing high-static-low-dynamic stiffness characteristics. The effectiveness of the method was verified by both theoretical and experimental analyses. The experimental results show that the vertical natural frequency of the optical platform was reduced from 2.00 to 1.37 Hz, the root mean square of displacement was reduced from 1.28 to 0.69 μm, and the root mean square of velocity was reduced from 14.60 to 9.33 μm/s, proving that the proposed method can effectively enhance the low frequency isolation performance of optical platforms.

scholarly journals A fast vibration-level adjustment method for low-frequency vibration calibration based on modified filtered-x least mean square algorithm

2020 ◽  
Vol 53 (3-4) ◽  
pp. 328-338
Author(s):  
Chao Li ◽  
Zhangwei Chen
Keyword(s):  
Control Method ◽  
Low Frequency ◽  
Successive Approximation Method ◽  
Control Input ◽  
Mean Square ◽  
Least Mean Square ◽  
Vibration Level ◽  
Calibration System ◽  
Low Frequency Vibration ◽  
Least Mean Square Algorithm

Traditionally, successive approximation method is applied to the vibration-level adjustment of vibration calibration system, which leads to a time-consuming work for low-frequency vibration calibration. In this paper, a novel control method for low-frequency vibration calibration system is proposed based on adaptive filter. First, the problem of the traditional vibration-level adjustment for low-frequency signals is depicted. Then, an adaptive control algorithm is presented, in which the control input is composed of two weighted sinusoidal signals with a phase difference of 90°. The weighted vector is updated in real time using a modified filtered-x least mean square algorithm. Unlike filtered-x least mean square algorithm, the proposed modified filtered-x least mean square algorithm does not require a pre-identification of the controlled system and has a reduced computational complexity. The convergence property of the proposed method is analyzed in detail. Finally, the proposed method is implemented on a low-frequency vibration calibration system. Experimental results show that the proposed modified filtered-x least mean square algorithm can significantly reduce the time of the vibration-level adjustment in low-frequency band.

scholarly journals Evaluating car's ride comfort and controlling vibration of suspension system based on adaptive PID control

2021 ◽  
Vol 1 (1) ◽  
pp. 1-9
Author(s):  
Zongwei Li ◽  
◽  
Vanliem Nguyen ◽  
Keyword(s):  
Root Mean Square ◽  
Pid Control ◽  
Ride Comfort ◽  
Vertical Vibration ◽  
Suspension System ◽  
Operating Conditions ◽  
Road Surface ◽  
Vehicle Body ◽  
Mean Square ◽  
Adaptive Pid Control

The vertical vibration of the vehicles not only affects the durability of parts of the vehicle and road surface but it also affects the driver’s ride comfort and health. The aim of this study is to evaluate the effect of the vertical vibration on the driver’s ride comfort and health under the vehicle different operating conditions. The adaptive PID control is then applied to improve the vehicle's ride comfort. To achieve this goal, a 2D vibration model for the cars with 5 DOF is established to simulate. The different operating conditions of the speed, road surface, load, and working time of the vehicles are respectively evaluated based on the vertical weighted r.m.s. acceleration responses of the driver’s seat and the international standard ISO 2631. The results show that the road surface condition has the greatest influence on the driver’s comfort and health. With the vehicle's suspension system controlled by the adaptive PID controller, the ride comfort of the vehicle is significantly improved under the various road surfaces. Particularly, at ISO level B, the vertical driver's seat root-mean-square acceleration value is greatly reduced by 24.99 % while the pitching vehicle body root-mean-square acceleration value is decreased by 25.10 % in comparison with the passive suspension system.

scholarly journals Prediction of Lower Extremity Multi-Joint Angles during Overground Walking by Using a Single IMU with a Low Frequency Based on an LSTM Recurrent Neural Network

Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 53
Author(s):  
Joohwan Sung ◽  
Sungmin Han ◽  
Heesu Park ◽  
Hyun-Myung Cho ◽  
Soree Hwang ◽  
...  
Keyword(s):  
Neural Network ◽  
Root Mean Square Error ◽  
Mean Square Error ◽  
Root Mean Square ◽  
Recurrent Neural Network ◽  
Joint Angle ◽  
Low Frequency ◽  
Measurement Unit ◽  
Mean Square ◽  
Overground Walking

The joint angle during gait is an important indicator, such as injury risk index, rehabilitation status evaluation, etc. To analyze gait, inertial measurement unit (IMU) sensors have been used in studies and continuously developed; however, they are difficult to utilize in daily life because of the inconvenience of having to attach multiple sensors together and the difficulty of long-term use due to the battery consumption required for high data sampling rates. To overcome these problems, this study propose a multi-joint angle estimation method based on a long short-term memory (LSTM) recurrent neural network with a single low-frequency (23 Hz) IMU sensor. IMU sensor data attached to the lateral shank were measured during overground walking at a self-selected speed for 30 healthy young persons. The results show a comparatively good accuracy level, similar to previous studies using high-frequency IMU sensors. Compared to the reference results obtained from the motion capture system, the estimated angle coefficient of determination (R2) is greater than 0.74, and the root mean square error and normalized root mean square error (NRMSE) are less than 7° and 9.87%, respectively. The knee joint showed the best estimation performance in terms of the NRMSE and R2 among the hip, knee, and ankle joints.

Effect of Low-Frequency Vibration on Human Body in Standing Position Exposed to Railway Vehicle

2018 ◽  
Vol 10 (3) ◽  
Author(s):  
Rajesh Govindan ◽  
Suraj Prakash Harsha
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Human Body ◽  
Low Frequency ◽  
Vertical Direction ◽  
Standing Position ◽  
Mode Shapes ◽  
Railway Vehicle ◽  
Lateral Direction ◽  
Low Frequency Vibration

In this paper, the dynamic characteristics of the human body were investigated by developing a 3-D finite element model based on 50th percentile anthropometric data for a 54 kg Indian male subject in standing position by considering human body segments as an ellipsoid. The finite element modal analysis is carried out to extract several low-frequency vibration modes and its vibration mode shapes were presented in this paper. The results show that the lowest natural frequency of the standing passenger model occurs in the fore-and-aft direction. The second natural frequency occurs in the lateral direction and the first order natural frequency of the standing passenger model in the vertical direction occurs at 5.379 Hz. The model will be helpful to predict the vibration response of human body under various vibration environment encounters in the railway vehicle.

scholarly journals Perception of Low Frequency Vibrations by Heavy Vehicle Drivers

2002 ◽  
Vol 21 (2) ◽  
pp. 65-75 ◽  
Author(s):  
Rayya Hassan ◽  
Kerry McManus
Keyword(s):  
Surface Roughness ◽  
Low Frequency ◽  
Subjective Assessment ◽  
Truck Drivers ◽  
Vehicle Body ◽  
Whole Body ◽  
Ride Quality ◽  
Related Factors ◽  
Low Frequency Vibration ◽  
Road Surface Roughness

A study was initiated to identify the levels and frequencies of heavy articulated vehicle body vibrations at which the drivers perceive the ride as uncomfortable. The study involved conducting a subjective assessment survey in which a panel of truck drivers were asked to rate the ride quality provided by a number of road sections with different surface roughness characteristics. The study's objective was achieved by correlating the mean panel ratings (MPRs) to road surface roughness contents in different one-third-octave bands of the roughness spectrum. The results showed that at 100 km/h, truck drivers object mainly to motions resulting from roughness excitations of the low frequency vibration modes of the truck body in the range 1.42 – 5.7 Hz. These results were validated by correlating MPRs with the levels of whole body vibrations measured on the driver's seat in a representative vehicle while traversing some test sections. MPRs were found to correlate well with the measured overall vibration total values and the likely comfort reactions to various magnitudes of overall vibration total values given by ISO 2631–1. The influence on MPRs of vehicle and driver related factors were also investigated and commented upon.

A Study of Vertical Vibration Transmissibility by the Human Body

2013 ◽  
Vol 325-326 ◽  
pp. 152-157 ◽  
Author(s):  
Mihaela Picu
Keyword(s):  
Root Mean Square ◽  
Human Body ◽  
Longitudinal Vibration ◽  
Whole Body ◽  
Mean Square ◽  
Low Frequencies ◽  
Acceleration Signal ◽  
Resonance Frequencies ◽  
Vibrating Platform ◽  
Vibration Transmissibility

The transmission of longitudinal vibration (generated by the vibrating platform Brüel & Kjær 4827) in the whole body of ten subjects was investigated. Altogether 200 individual tests were made. Vibration was measured with 356A16 PCB Piezotronics triaxial accelerometers fixed to the toes, ankles, lumbar, cervical, fingers, elbow and shoulder. Vibrations were analyzed with a multiple acquisition vibrations system NetdB. Data were processed using dBFA Suite. Vibration time was 1min and frequency range was between 10-40Hz, because the low frequencies are the resonance frequencies for the human body. Body vibration transmissibility was determined by the ratio of root mean square acceleration signal from accelerometer by the root mean square of acceleration signal from the vibrating platform. It was found that the accelerations at the lumbar level are more attenuated than the accelerations at the ankle level.

Analysis of motorcycle vibration comfort based on rigid-flexible coupling model

2020 ◽  
Vol 51 (6) ◽  
pp. 110-115
Author(s):  
Yu Feng ◽  
Xie Jun
Keyword(s):  
Low Frequency ◽  
Coupling Model ◽  
Design Stage ◽  
Vibration Level ◽  
Subjective Impression ◽  
Flexible Coupling ◽  
The Road ◽  
Low Frequency Vibration ◽  
Road Roughness ◽  
Road Excitation

Based on the rigid-flexible coupling model, this article utilized ADAMS to establish a dynamics model of a motorcycle, in which the engine excitation and road excitation were determined. According to the ISO5349 and ISO2631 standards, the vibration of the motorcycle at 60 km/h was analyzed. The results showed that the high-frequency vibration of the engine accounted for the most vibration at the handle when driving on the B-class road at 60 km/h, and the vibration level was uncomfortable. In contrast, the low-frequency vibration of the road roughness was the main excitation of the cushion vibration, and the vibration level was relatively uncomfortable. These results were in accordance with the subjective impression on human observers, indicating that the vibration comfort analysis method based on the rigid-flexible coupling model was correct and effective to provide theoretical basis for the subsequent improvement and modification early in the design stage.

scholarly journals Influence of Low Frequency Vibration on the Human Body

1991 ◽  
Vol 27 (Supplement) ◽  
pp. 144-145 ◽  
Author(s):  
M. Uchikune ◽  
Y. Yoshida
Keyword(s):  
Human Body ◽  
Low Frequency ◽  
Low Frequency Vibration
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