Active-Side Calculation Method for a Backhoe Hydraulic Excavator with Incomplete Digging Resistance in a Normal State

Abstract

The digging resistance in a normal state is the key to excavator design and automated excavation. It is difficult to accurately predict, simulate, or directly measure the digging resistance in a normal state due to uncertainties in the soil properties and excavation parameters. In this paper, a research idea is proposed that uses the working device as the entry point to indirectly calculate the digging resistance in a normal state by measuring the motion parameters and the cylinder pressure intensity. Based on the rule of combination for spatial force systems, a method for combining and projecting the system of the digging resistance is proposed in which the system is projected as six parts, and the tangential force, normal force, and bending moment in the plane of symmetry of the working device are the objects of the solution to avoid redundant equations. Based on kinematics and dynamics models of the excavator and the force and moment equilibrium conditions of the working device, equations for the active-side calculation of the incomplete digging resistance are derived. Based on these equations, the motion parameters of the working device and data on the cylinder pressure intensity obtained by measurement are used to calculate the incomplete digging resistance. The validation scheme and process proposed use the incomplete digging resistance as the external load to obtain the simulated stress of the working device through transient analysis. The simulated stress and the measured stress corresponding to the position of the measurement point are extracted and compared. The results show that there is a difference in the size of the numerical value between the simulated and measured stress, but the variation law is highly consistent, which validates the calculation method. In this paper, an active-side calculation method is provided for the incomplete digging resistance in a normal state without considering the soil-tool interaction relationships, which lays a theoretical foundation for the study of the digging resistance characteristics in a normal state, as well as excavator design and automated excavation.

Bucket structure optimization of backhoe hydraulic excavator based on compound digging trajectory and limit digging force

“…The main digging area of the excavator is below the ground and the influence of the main digging area on the digging performance is considered at the beginning of the excavator design, therefore, the digging trajectory in the main digging area is chosen as the premise of the study. A compound digging trajectory was obtained through the compound digging action of excavator, 23 this trajectory is shown in Figure 2(b), the corresponding tooling clamp angle variation of this trajectory is shown in Figure 3.…”

Research on the matching characteristics of the theoretical digging force of a backhoe hydraulic excavator

“…Two different conditions of free continuous digging in the normal digging area were selected, where Condition 1 was the operation of normal soil piling on the stopping surface and Condition 2 was the operation of free continuous trenching in the main digging area. Based on the incomplete digging resistance model 8 established by the team, the angular displacement data required in the tests included the angle of rotation of the boom relative to the body, the angle of rotation of the stick relative to the boom and the angle of rotation of the bucket relative to the stick; the required pressure data included the pressure data of the rod and rodless chambers of the boom hydraulic cylinder, stick hydraulic cylinder and bucket hydraulic cylinder; and the angular displacement and sensor location layout in the tests are detailed in reference 25 .…”

“…Therefore, the authors' team has established that the working object is a common tertiary soil mixed with stones, the working condition is a common mounding operation before stopping and trenching in the main digging area, and the digging method is constant free continuous compound digging. A method for calculating the incomplete digging resistance using measured data from the working devices has been proposed; see reference 8 for details.…”

Dynamic digging force modeling and comparative analysis of backhoe hydraulic excavators

“…Consequently, recent studies have increasingly employed methods such as numerical simulation to comprehensively describe the digging resistance from various perspectives. A model was developed by Ren et al [3] to address the issue of incomplete digging resistance on the active side during normal digging. This model utilizes indirect measurements of the work unit motion parameters and hydraulic cylinder pressure, with the work unit serving as the starting point for analysis.…”