Abstract:The aim of the paper is to present the experimental results for material model of the sand, case of wet and dry probe. Since traction and side forces derivation methodology and tire-round interaction models for onroad vehicles are widely described, there is a lack of methods for off-road vehicles. The methodology, presented in this work, includes test in various ground conditions and different driving direction. Test results, presented in the paper were acquired for dry and humid sand, for various tire tilt an… Show more
“…3 total longitudinal and transverse forces related to geometrical axes of the wheel can be expressed as below: Figure 3 Geometrical model of the wheel, top view. x–y—coordinate axes relate to the movement direction, x wheel –y wheel —coordinate axes related to the wheel geometry, F long —measured longitudinal force related to the movement direction, F lat —measured lateral force related to the movement direction, F—the resultant force related to coordinate axes of movement direction, F long wheel —longitudinal component of the force related to geometrical wheel axes, Flat wheel—lateral component of the force related to geometrical wheel axes, α w —slip angle (between movement direction and wheel coordinate system) 16 . …”
Section: Methodology Descriptionmentioning
confidence: 99%
“…Input parameters for the model are 16 . Slip angle, Normal force (wheel vertical load), Wheel pressure, Ground pattern.…”
Section: Wheel-surface Model Formulationmentioning
Since the wheel interaction with a certain terrain cases (asphalt, concrete) are known and well described in case of straightforward motion and non-slip and slip cornering conditions, the skid-steered wheeled vehicles case needs to be analyzed. Side-slip for various attack angle has to be investigated. The main area of interest of research that is shown in the project is energy demand calculation of skid-steered wheeled vehicles in various terrain conditions. Certain cases of all-electric vehicles with individual electric motors per wheel demand a precise assessment of longitudinal and lateral forces in order to perform the fully controlled turn. Experimental stand designed and developed by authors allows to test the wheel-surface interaction for various terrain conditions and different driving directions. Test data were acquired for dry and wet sand and granite pavement. Traction and side forces were acquired and used to identify the wheel-soil interaction model parameters for unpropelled wheel. Results in a form of time series including longitudinal and lateral forces show the relation between attack angle, load and surface conditions in terms of stick and slip phenomenon that is essential for skid-steering dynamics calculations. Measurement results are then used for calculation of longitudinal and lateral forces coefficients as a function of attack angle and vertical load. Test were performed in natural environment, thus they are affected by changeable conditions. Multiple runs are used for elimination of that influence. Described experiments are a part of the project that includes results generalization using test validated FEM model. Described work is not intended to develop new ground-tire interaction models, it is focused on numerically efficient traction effort calculation method for various conditions including passive mode—unpropelled wheel.
“…3 total longitudinal and transverse forces related to geometrical axes of the wheel can be expressed as below: Figure 3 Geometrical model of the wheel, top view. x–y—coordinate axes relate to the movement direction, x wheel –y wheel —coordinate axes related to the wheel geometry, F long —measured longitudinal force related to the movement direction, F lat —measured lateral force related to the movement direction, F—the resultant force related to coordinate axes of movement direction, F long wheel —longitudinal component of the force related to geometrical wheel axes, Flat wheel—lateral component of the force related to geometrical wheel axes, α w —slip angle (between movement direction and wheel coordinate system) 16 . …”
Section: Methodology Descriptionmentioning
confidence: 99%
“…Input parameters for the model are 16 . Slip angle, Normal force (wheel vertical load), Wheel pressure, Ground pattern.…”
Section: Wheel-surface Model Formulationmentioning
Since the wheel interaction with a certain terrain cases (asphalt, concrete) are known and well described in case of straightforward motion and non-slip and slip cornering conditions, the skid-steered wheeled vehicles case needs to be analyzed. Side-slip for various attack angle has to be investigated. The main area of interest of research that is shown in the project is energy demand calculation of skid-steered wheeled vehicles in various terrain conditions. Certain cases of all-electric vehicles with individual electric motors per wheel demand a precise assessment of longitudinal and lateral forces in order to perform the fully controlled turn. Experimental stand designed and developed by authors allows to test the wheel-surface interaction for various terrain conditions and different driving directions. Test data were acquired for dry and wet sand and granite pavement. Traction and side forces were acquired and used to identify the wheel-soil interaction model parameters for unpropelled wheel. Results in a form of time series including longitudinal and lateral forces show the relation between attack angle, load and surface conditions in terms of stick and slip phenomenon that is essential for skid-steering dynamics calculations. Measurement results are then used for calculation of longitudinal and lateral forces coefficients as a function of attack angle and vertical load. Test were performed in natural environment, thus they are affected by changeable conditions. Multiple runs are used for elimination of that influence. Described experiments are a part of the project that includes results generalization using test validated FEM model. Described work is not intended to develop new ground-tire interaction models, it is focused on numerically efficient traction effort calculation method for various conditions including passive mode—unpropelled wheel.
“…In the literature, information on specialist stands designed for testing vehicle suspension systems with omnidirectional wheels is limited. The solutions specified in the literature are based on traditional wheels and the determination of resistance [ 16 ]. Earlier research on mobile robots that are fitted with omnidirectional wheels has covered topics such as the kinematic modelling of vehicle movement [ 17 ] and control methods [ 18 , 19 ].…”
This paper describes a test stand for determining the kinematic excitation originating from the contact between a vehicle’s wheel and the ground, thus acting on the single suspension upright of the vehicle. This excitation is unique to the movement of omnidirectional wheels and originates from the irregular envelope of the wheel. The presented attitude enables the vertical displacement of the wheel’s axis rolling on a horizontal surface to be determined. This work includes experimental results considering different wheel orientations against the direction of movement.
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