Task space-based dynamic trajectory planning for digging process of a hydraulic excavator with the integration of soil–bucket interaction

Abstract

In this paper, a task space-based methodology for dynamic trajectory planning for digging process of a hydraulic excavator is presented, with the integration of soil–bucket interaction. An extended soil–bucket interaction model, which adds the resistive moment compared to the previous models, is provided in this research. This improved model is validated by comparing with the measurement data taken from field experiments before integrating it into a dynamic model of an excavator. Further, Newton–Euler method is used for the derivation of the dynamics of each link of the excavator to determine the joint forces, which can cause the machine damage. The position and orientation trajectories of the bucket in the task space are parameterized by using the B-splines, so as to achieve the task-oriented operations and ensure the operation flexibility. The joint space motion characteristics are obtained by solving the inverse kinematics of the working mechanism of an excavator. Moreover, to avoid the operation uncertainty for a given bucket tip position trajectory and reduce the computational effort, the self-motion parameters are introduced when solving the inverse kinematics of the redundant working mechanism. All these self-motion parameters are taken as a set of design variables in the trajectory optimization problem. Also, the limits on the hydraulic driving forces, joint angles, angular velocities and accelerations, as well as bucket capacity are considered as the optimization constraints for the digging process. Finally, optimization examples of two typical digging categories (i.e. level digging work and slope digging work) are given to demonstrate and verify the capabilities of the new methodology proposed in this research. The results show that the proposed method can effectively generate the optimal trajectories satisfying the following criteria: time efficiency, energy efficiency, and least machine damage. This work lays a solid foundation for motion planning and autonomous control of an excavator.

Prediction of the Cutting Resistance Force of the Soil Containing Stony Fractions

“…1* , Тургунбаев М.С. 2 1 И. Раззаков атындағы Қырғыз мемлекеттік техникалық университеті, Бішкек, Қырғызстан;…”

A Novel Method of Soil Parameter Identification and Force Prediction for Automatic Excavation

“…Furthermore, using the cavity expansion theory, Park established a resistance prediction model when the bucket penetrated the soil [19]. This model was used for soil resistance prediction in the study by Bennett et al [9] and Zou et al [20]. However, due to the complexity of this model and the inability to reverse the soil parameters from the force, directly using this model to identify soil parameters is difficult.…”

“…This condition is different from the soil box experiment in Test 1, where it is convenient to use instruments to obtain accurate parameters of the test soil. As the soil properties suffer after excavation, and obtaining the entire soil bulk for parameter testing is difficult, the field experiment can only estimate the parameters according to the soil conditions on the site [20], which are inaccurate. The average values of cylinder pressures measured by sensors in multiple experiments are shown in Fig.…”

“…Similarly, Zeng et al established a soil resistance model based on the principle of soil mechanics and applied it to predict the resistive force of lunar soil collection [18]. Furthermore, Zou added the soil inertial force to Park's model [19] and used it to predict excavation resistance and trajectory planning [20]. Among these models, the FEE model proposed by Reece is considered as a classic model for soil-tool mechanical analysis and is widely used in soil resistance prediction [9], [14].…”

Dynamic modelling and accuracy analysis for front-end weighing system of LHD vehicles

“…In fact, in this field, the weighing research of excavators has achieved better results, which largely owes to the establishment of a more accurate load dynamic model of front-end working mechanism (e.g., Newton-Euler or Kane method), 4,22–24 so high accurate weighing has higher requirements for the load dynamic models of working mechanism. At present, some scholars have carried on the research in the kinematics or dynamics (ignored the load effect) and the control for the front-end mechanism of LHD or loader.…”