Excavators are crucial heavy equipment on construction sites, performing diverse earthwork tasks. The construction worksite is experiencing a labor shortage due to an aging workforce. Training new operators requires significant time and resources. Furthermore, the construction environment is hazardous, with a higher rate of excavator-related accidents. Autonomous excavators offer an effective solution by reducing the need for operators in risky environments and substituting skilled workers. Trajectory planning algorithms are vital for autonomous excavators, with skilled operators’ paths serving as important references. However, many studies do not adequately consider skilled operators’ methods or the actual excavation environment. This paper introduced a rule-based algorithm for excavation trajectory planning using terrain data. Based on analysis results of skilled operators’ paths, the proposed algorithm categorizes the excavation process into three stages, depending on the usage rate of the excavator"s joints. Terrain data were derived by projecting point clouds from a stereo depth camera onto a side plane. The path was modified if the excavation volume exceeded a set limit to avoid excessive load. The algorithm was tested with a 30-ton excavator, demonstrating validation of operability and efficiency similar to that of skilled operators.

This study determined the equivalent moment of inertia of the upper rotating body of an excavator, for the inertial endurance test of an excavator slewing system. The input speed and torque of the slewing reducer were measured by an excavator slewing test, and the equivalent moment of inertia of the upper rotating body of the excavator was calculated using iterative calculation. We developed a dynamic simulation model of the excavator slewing system, and validated the model by comparing it with the slewing test results. Using the validated model, we further developed a simulation model for the inertial endurance test, that considers the moment of inertia of the upper rotating body of an excavator. We concluded that the new dynamic model for the inertial endurance test of an excavator slewing system well exemplified the actual slewing test results.