Experimental Assessment of the Ride Comfort of Farm Tractors

2013 ◽  
Author(s):  
Stefano Dominoni ◽  
Massimiliano Gobbi ◽  
Giampiero Mastinu ◽  
Giorgio Previati
Keyword(s):  
Ride Comfort ◽  
The Body ◽  
Whole Body ◽  
Huge Number ◽  
Comfort Index ◽  
Proper Comparison ◽  
Vertical Accelerations ◽  
The Time Domain ◽  
Iso 2631 ◽  
Whole Body Vibrations

The paper is focused on the assessment of the ride comfort of that farm tractors. The problem of assessing the ride comfort is crucial due to the fact that operators spend part of their own lives on board of such machines, exposed to whole body vibrations potentially harmful for their health. The paper deals with the experimental measurement of the relevant vibration occurring at the tractor body, at the cabin and at the seat. The focus is on which accelerations are actually relevant and have to be taken into account. A number of farm tractors have been instrumented and run under monitored conditions. The test track was equipped with a number of cleats able to force at resonance the cabin and the seat. The six motions of the tractor body and the six motions of the cabin were measured. The motion of the seat was measured. The signals have been processed in the time domain. Some interesting occurrence have been highlighted referring to the amplification that a badly regulated seat can provide under certain circumstances. The comfort index was computed according with ISO 2631 and other standards. The acceleration of the seated subject was described at different positions on the body. It turned out that the acceleration of the head was particularly relevant for establishing a comparison among different tractors. Synthetic indices have been derived from the measured data able to correlate the subjective drivers’ feeling with the measured level of vibration. The conclusion is that for a proper comparison of the ride performance of different farm tractors a huge number of measurements are needed. There is no possibility to record only the vertical accelerations to assess the ride comfort of farm tractors.

scholarly journals Passsenger Ride Comfort and International Roughness Index Specifications in the Slovak Republic

2019 ◽  
Vol 21 (1) ◽  
pp. 14-21
Author(s):  
Peter Mucka ◽  
George Juraj Stein ◽  
Peter Tobolka
Keyword(s):  
Road Network ◽  
Ride Comfort ◽  
Slovak Republic ◽  
Point Of View ◽  
Whole Body ◽  
Acceleration Response ◽  
International Roughness Index ◽  
Roughness Index ◽  
Iso 2631 ◽  
Whole Body Vibrations

New original results are presented on relation between passenger’s whole-body vibration (WBV) and longitudinal road unevenness characterised by the International Roughness Index (IRI) in 100-m segments. Measurements were provided in nine different cars of six vehicle categories operated on about 1860 km of road network. Vibration total value based on the root mean square (RMS) of the frequency-weighted acceleration was used to quantify the ride comfort at seat surface and seat base (i.e. vehicle floor) in three orthogonal axes. The relations between passenger’s acceleration response, comfort reaction levels according to the ISO 2631-1: 1997 and the IRI road unevenness classes, used by the Slovak Road Administration, were estimated. Results indicated higher WBV by ~ 20 % on the motorways than on the 1st and 2nd class roads in the same IRI road class. Using the same IRI road classes for motorways and the 1st and 2nd class roads seems not to be appropriate from the point of view of the whole-body vibrations.

scholarly journals Occupational Vibration in Urban Bus and Influence on Driver’s Lower Limbs

2018 ◽  
Vol 4 (1) ◽  
pp. 56-66
Author(s):  
M. Cvetkovic ◽  
J. Santos Baptista ◽  
M. A. Pires Vaz
Keyword(s):  
Whole Body Vibration ◽  
Working Environment ◽  
Lower Limbs ◽  
Whole Body ◽  
Body Vibration ◽  
Prisma Statement ◽  
Physical Changes ◽  
Iso 2631 ◽  
The Impact ◽  
Whole Body Vibrations

The whole-body vibration occurs in many occupational activities, promoting discomfort in the working environment and inducing a variety of psycho – physical changes where consequences as a permanent dysfunction of certain parts of the organism may occur. The main goal of this short systematic review is finding the articles with the most reliable results relating whole-body vibrations to buses and, to compare them with the results of drivers’ lower limbs musculoskeletal disease which occurs as a consequence of many year exposure. PRISMA Statement Methodology was used and thereby 27 Scientific Journals and 25 Index - Database were searched through where 3996 works were found, of which 24 were included in this paper. As a leading standard for analysis of the whole-body vibration the ISO 2631 – 1 is used, while in some papers as an additional standard the ISO 2631-5 is also used for the sake of better understanding the vibrations. Furthermore, the European Directive 2002/44 / EC is included where a daily action exposure to the whole-body vibrations is exactly deter-mined. All the results presented in the paper were compared with the aforesaid standards. After having searched the databases, papers that deal with research of the impact of the vibration on the driver’s lower limbs did not contain any information’s on the described problem.

Series Active Variable Geometry Suspension Robust Control Based on Full-Vehicle Dynamics

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Cheng Cheng ◽  
Simos A. Evangelou
Keyword(s):  
High Performance ◽  
Performance Enhancement ◽  
Ride Comfort ◽  
The Body ◽  
Control Technique ◽  
Variable Geometry ◽  
Physical Constraints ◽  
Car Model ◽  
Time Domains ◽  
Vertical Accelerations

This paper demonstrates the ride comfort and road holding performance enhancement of the new road vehicle series active variable geometry suspension (SAVGS) concept using an H∞ control technique. In contrast with the previously reported work that considered simpler quarter-car models, the present work designs and evaluates control systems using full-car dynamics thereby taking into account the coupled responses from the four independently actuated corners of the vehicle. Thus, the study utilizes a nonlinear full-car model that represents accurately the dynamics and geometry of a high performance car with the new double wishbone active suspension concept. The robust H∞ control design exploits the linearized dynamics of the nonlinear model at a trim state, and it is formulated as a disturbance rejection problem that aims to reduce the body vertical accelerations and tire deflections while guaranteeing operation inside the existing physical constraints. The proposed controller is installed on the nonlinear full-car model, and its performance is examined in the frequency and time domains for various operating maneuvers, with respect to the conventional passive suspension and the previously designed SAVGS H∞ control schemes with simpler vehicle models.

scholarly journals Raised Pedestrian Crossings: Analysis of Their Characteristics on a Road Network and Geometric Sizing Proposal

2019 ◽  
Vol 9 (14) ◽  
pp. 2844 ◽  
Author(s):  
Loprencipe ◽  
Moretti ◽  
Pantuso ◽  
Banfi
Keyword(s):  
Urban Areas ◽  
Ride Comfort ◽  
International Standards ◽  
Motor Vehicles ◽  
Whole Body ◽  
Vehicle Speed ◽  
Traffic Calming ◽  
Dynamic Performances ◽  
Vertical Accelerations ◽  
Pedestrian Crossing

In urban areas traffic-calming strategies and pedestrian friendly measures are often adopted to reduce the adverse impacts of motor vehicles on vulnerable users. This study surveyed 24 raised pedestrian crossings (RPCs) to examine their geometrical and functional characteristics. Geometric characteristics, location, administrative and effective vehicle speed, and the whole-body vibration acceleration induced to vehicle occupants while they are passing over, were considered. In addition to the analysis of the field data, geometrical and functional criteria to design RPCs were carried out. Particularly, two design approaches have been considered. In the first one, RPC provides a designated route across a carriageway raised to the same level, or close to the same level, as the sidewalks that provide access to the pedestrian crossing. In such condition, an RPC is not a traffic-calming device and its design should satisfy geometrical and comfort criteria for designing roads. The results from the surveys demonstrated that less than 10% of RPCs guarantee ride comfort. According to the second design approach, an RPC acts both as a marked pedestrian feature and as a traffic-calming device (i.e., it is trapezoidal in shape with sharp edges). The analysis of the vertical accelerations on vehicle occupants reveal that more than 90% of the surveyed RPCs comply with geometrical and dynamic criteria for speed tables. Extreme variations concerning the observed geometrical characteristics of RPCs and the modelled dynamic performances have been observed: It results in noneffective treatments. Therefore, the results of this study would contribute to providing geometric best practices for overcoming the regulation gap in this subject, and designing RPCs according to international standards.

Development of Seated Human Model With Uncertain Parameters and Estimation of the Ride Comfort

2018 ◽  
Author(s):  
Jong-Jin Bae ◽  
Namcheol Kang
Keyword(s):  
Ride Comfort ◽  
Probability Distributions ◽  
Equations Of Motion ◽  
Degree Of Freedom ◽  
Human Model ◽  
Whole Body ◽  
Mode Shapes ◽  
Comfort Index ◽  
Parametric Studies ◽  
Nonlinear Equations Of Motion

This study deals with the biodynamic responses of the 5-degree-of-freedom mathematical human model to whole-body vibrations in a vehicle. The nonlinear equations of motion of the human model were derived, and the spring constants and damping coefficients were extracted from the experimental data in the literature using optimization process. The natural frequencies and mode shapes were also calculated using linearized human model. In order to examine the effects of the variations of the human parameters, the parametric studies with respect to the stiffness values were performed. The mode veering phenomenon was observed between fourth and fifth mode of the linearized human model. In addition, the frequency responses of the nonlinear 5-degree-of-freedom model were also obtained, and the frequency shift and jump phenomena were observed. Furthermore, the estimation of the ride comfort was performed using CarSim and Matlab/Simulink with several road profiles according to ISO classification. Besides, we also calculated the ride comfort index using BS 6841 standard. In order to calculate the statistical responses of human model, the Monte-Carlo simulation applied to the nonlinear human model having uncertain stiffness assuming Gaussian distribution. These stochastic approaches enable the proposed human model to estimate probability distributions of the ride comfort index.

Ride Quality of High-Speed Trains Traveling Over the Corrugated Rails

2006 ◽  
Author(s):  
H. Farahpour ◽  
D. Younesian ◽  
E. Esmailzadeh
Keyword(s):  
High Speed ◽  
Ride Comfort ◽  
The Body ◽  
Ride Quality ◽  
Comfort Index ◽  
Suspension Systems ◽  
Power Spectral ◽  
High Speed Trains ◽  
Train Speed ◽  
Secondary Suspension

Ride comfort of high-speed trains is studied using Sperling's comfort index. Dynamic model is developed in the frequency domain and the power spectral density (PSD) of the body acceleration is obtained for four classes of tracks. The obtained acceleration PSD is then filtered using Sperling's filter. The effects of the rail roughness and train speed on the comfort indicators are investigated. A parametric study is also carried out to evaluate the effects of the primary and secondary suspension systems on the comfort indicators.

Sensations, Perception Thresholds and Temporary Threshold Shifts of Whole Body Vibrations in Sitting and Standing Posture

1986 ◽  
Vol 5 (2) ◽  
pp. 68-77 ◽  
Author(s):  
Ulf Landström ◽  
Ronnie Lundström
Keyword(s):  
Subjective Experience ◽  
Whole Body Vibration ◽  
The Body ◽  
Whole Body ◽  
Standing Posture ◽  
Sitting Posture ◽  
Body Vibration ◽  
Vibration Fatigue ◽  
C 30 ◽  
Whole Body Vibrations

The experiments were conducted to evaluate the subjective experience associated with sinusoidal whole body vibration. Exposures were carried out in vertical (z) direction with the subject placed in upright sitting and standing positions. According to the present results, the vibration perception level is approximately the same for both postures, about 80–90 dB, (re 1 μm/s2 (r.m.s)) when comparing frequencies below 100 Hz. The threshold values were found to be influenced by the body weight, heavy people being more sensitive to whole body vibration in sitting posture, light people being more sensitive to vibrations in standing posture. Furthermore, the present study clearly shows the existence of temporary threshold shifts (TTS) in perception of whole body vibration after 5 minutes of vibration fatigue. If measured c. 30 seconds after the end of the exposure the temporary threshold shifts were in the magnitude of 10 dB.

scholarly journals WHOLE BODY AND HAND-ARM VIBRATIONS ON OFF-ROAD VEHICLE USED IN ACADEMICALS COMPETITIONS

2017 ◽  
Vol 24 (5) ◽  
pp. 375-382
Author(s):  
Fábio Celso Oliveira ◽  
Geice Paula Villibor ◽  
Joseph Kalil Khoury Junior ◽  
Éder Harisson Ferreira Lima
Keyword(s):  
Whole Body Vibration ◽  
Whole Body ◽  
Vibration Exposure ◽  
Military Operations ◽  
Road Vehicles ◽  
Body Vibration ◽  
Acceleration Level ◽  
Vertical Accelerations ◽  
Warning Limits ◽  
Iso 2631

Off-road vehicles, baja type, are designed for locomotion on irregular terrains with several obstacles, to pull loads with effciency, furthermore, are compact and easy to operate. Such vehicles have wide use in agriculture, construction, transportation and military operations. Baja vehicle provide to pilot an exposure to high levels of mechanical vibrations. With the present work aimed to determine the whole body vibration and hand-arm vibration in the pilot using the vehicle designed by UFVbaja team. The vibrations levels incident on the pilot was measured in three different terrain conditions and different forward speeds. It was determinate the root mean square acceleration and daily vibration exposure at the seat pad and hand-arm of pilot. For whole body vibration was obtained the daily vibration dose value. The values were confronted with standards ISO 2631-1. The acceleration level, normalized to 8 hour, exceeded the warning limits for all worked conditions. To Baja vehicle operating in plowing soil, the transverse and vertical accelerations exceeded the limit level. In general, incident acceleration levels on the pilot were considered high, which reinforces the need for seats projects of suspension, steering and seat that effectively reduce the vibration transmitted to pilot body and hand-arm system.

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