Dynamics of walking movement of an experimental vehicle

Abstract

Introduction. The work examines an experimental vehicle with a combined method of movement – rolling and walking, designed for transporting agricultural goods in field conditions. The choice of movement method depends on the bearing capacity of the supporting surface and the roughness of the terrain. When performing a walking method of movement by a vehicle, the most dangerous stage is the transfer of the first and third moving parts, at the moment of separation from the supporting surface of the movers. The peculiarity of performing walking movement by an experimental vehicle is due to changes in the reactions of the supporting surface between the movers in contact with the ground, as well as the roll angle of the vehicle body, due to changes in the position of the center of mass of the entire structure when performing a “step”. The nature of the change in dynamic parameters during the walking method of moving an experimental vehicle is an urgent task, the research results of which are presented in the work for the period of performing one “step”.
Object. The subject of the study is the laws of change in tangential and normal reactions of the supporting surface, as well as the roll angle of an experimental vehicle on soil surfaces such as loam, fine sand, and clay.
Materials and methods. A mathematical model of machine dynamics when moving over various soils has been developed. The viscoelastic-plastic model was adopted as a soil model.
Results and conclusions. As a result of numerical experiments, the range of changes in the kinematic parameters of the machine was determined, the characteristics of the redistribution of tangential and normal reactions of the supporting surface were obtained, and the roll angle when performing a “step” by the first moving part of the experimental vehicle on various ground surfaces was determined. Thus, the minimum reaction to the middle moving part was 670 N on a clay soil surface, and the maximum was 880 N on fine sand. The minimum roll angle was φ2=2.23⁰ on fine sand, and the maximum φ3=2.75⁰ on clay soils.