Estimation of Soil Pressures Based on the Pressures in the Hydraulic System for a Legged Forestry Machine

Harvesting operations with wheeled forestry machines can bring great harm to wet soils due to the machine weight and wheel slip. Factors such as the reduction of wheel slip, machine weight and total area affected by forestry machines are crucial in protecting soils. The accurate measurement of the pressure introduced by forestry machines to the soil, without harming the structure of the ground nor making assumptions of the tire or ground behavior, poses a challenge. Within this article a method to calculate the contact soil pressure, of a portal advancing mechanism for sensitive soils is presented. The results are then further evaluated based on simulative results. B y using the kinematics of the legged machine, it becomes possible to determine the soil pressure without making rough assumptions of the legs or the ground. The kinematic allows to measure the forces of the hydraulic actuators that are holding the legs in position. Through this, a direct calculation of the force which is transferred to the ground can be made. To determine the forces of the hydraulic actuators in a movement cycle, a coupled simulation of the kinematic and hydraulic system is set up. ... mehrUsing the determined pressures in the cylinders the exerted force on the ground is calculated. The developed calculation method has been set up in such a manner that the results can easily be compared to real world test data in future studies. In addition, the effects of this particular legged forestry machine on the ground will be compared to other machine types under the consideration, that with this new concept no slip is expected. Using this approach, the soil pressure and the impact on the ground of a legged forestry machine can be evaluated in an early stage of development.