Mikleš M., Helexa M., Mikleš J. (2017): Research on forest terrain roughness as a source of dynamic action on the vehicle. J. For. Sci., 63: 363-369.The issue of terrain conditions is very complex and its description is approached from different perspectives and with different objectives. Because it consists of the gathering of basic information for a mobile object, a wheeled forestry tractor, the terrain-vehicle approach was taken as the basis. Ground conditions are part of the operating conditions of wheeled forestry tractors. Uneven ground can be regarded as a source of vibration in the vehicle -towing truck. In this respect, given the random shape of the surface roughness, the solution to vibrations leads to a terrain correlation analysis in order to obtain a correlation function and power spectral density of the ground surface. Scanning of the ground micro-profile was performed using a device for quick terrain scanning, which from the mechanical aspect consists of a towing vehicle and a measuring carriage. Correlation function and power spectral density are the evaluation based on ground micro-profile measurements and the results of calculations. Measurements of forest terrain (road) micro-profile were done in the area of Little Fatra and Little Carpathians in Slovakia. In geological terms, the measurements were done in an area with the occurrence of gneiss, granite, limestone and flysch. No measurements were performed in a sandy area.

ABSTRACT:A model of the probability of operating conditions describes running of the examined unit in form of connected probabilities of occurrence of monitored operating factors can be stochastically dependent or independent. Operating factors will be divided, in order to the opportunity of the monitoring, on the quantification of the probability model of the forest skidder, into two parts: terrain conditions (micro and macrorelief of the terrain) and operating conditions (a line of operation, a load, a distance). In this paper opportunities are sought of the relationship between terrain conditions and operating conditions in the defined signification. A field of the application is in a monitoring of operating conditions, planning and organisation of the experiment, in this field. Keywords: probability model; traction force; engine power; tyre characteristics A probability model of operating conditions describes the operation of an examined machine in the form of conjugated occurrence probabilities of particular operation factors. Operation factors can be either stochastic dependent or independent.While quantifying the probability model of a skidder operation, the operation factors are due to the examination of possibilities divided (Mikleš et al. 2010) into two categories: terrain conditions (terrain micro-and macroprofile), operating conditions in a narrower sense (operation period, load, distance).A probability model of operating conditions is to be deduced from the following discussion. Let the operation factors x 1 , x 2 , …, x n describing operating conditions be random/arbitrary functions of the argument l and the operation of the machine be the simultaneous realisation of these factors. Then the effect that "the machine is situated" (works) in the j th operating conditions is equivalent to the effect when the operating conditions are equivalent to the effect when the operation factors x 1