First Tests on a Prototype Device for the Active Control of Whole-Body Vibrations on Agricultural Tractors
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In old tractors, apart from tires, the only means for the reduction of vibration was a seat consisting of a sheet metal shell supported by a simple U-shaped spring. Today, the effects of seats, cabins, axles, suspensions and tires combine to increase comfort and safety at levels that were once unimaginable. Trying to improve the safety and comfort levels in the work-places, this work describes a first experience on the application of a vibration active control system (AVC) on a medium-power agricultural tractor. Its seat’s suspension was integrated by an electromagnetic actuator generating movements opposing to those caused by soil unevenness, based on the signals received from two accelerometers measuring the vibrations at the seat and at the cab platform. A further instrumentation measured the driver whole-body vibration providing the frequency analysis and the calculation of the weighted accelerations and the acceleration sum vector (av). The tests were carried out on a compacted ground circuit with a section with natural unevenness. They aimed at evaluating the effects of the AVC system by comparing the whole-body vibrations measured in “ON” and “OFF” modes. The maximum accelerations always occurred at 2.5 Hz. The reduction mostly regarded the az component (“ON”:0.66 m s−2;“OFF”:0.94 m s−2). The resultant av were 1.47 m s−2 and 1.97 m s−2 respectively for “ON” and “OFF” modes. In both tests, the differences between the values of weighted accelerations were lower due to the effect of the filter “A”. The above data resulted from the acquisition along the entire established paths. Since only limited sections of the tracks were uneven, the results underestimated the actual reduction achieved on the obstacles, which becomes more evident by observing the FFT diagrams.
KeywordsVibration Active vibration control Tractor Driver comfort
This work was supported by the sub-project AgriDigit financed by the Ministry of Agricultural, Food and Forestry Policies (MiPAAF) (DM 36503/7305/2018).
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