Validation of an analytical method for payload estimation in excavators

In this proposed paper, a measurement based validation for a previously developed payload estimation method for excavators [1] is presented. The payload here refers to the weight exerted at the operating end (bucket) of the working attachment of an excavator due to the amount of material in the bucket. The proposed method employs an analytical approach, relying on calculating the payload as a function of the joint torques of the excavator working attachment. Since this approach requires the knowledge of the inertial parameters of the working attachment, a method to estimate these was proposed. The mass, center of mass and mass moment of inertia of each link are estimated recursively using simple motion trajectories of the working attachment. Once the inertial parameters are thus estimated, the payload can be estimated as a function of joint torques. Both these estimation methods were validated using measurements done on an 18 t hydraulic excavator. The paper discusses in detail the measurement runs performed for the validation, as well as the subsequent evaluation of the measurement data. Finally, the quality of the results is elaborated on, and suggestions for improvement of the accuracy and reproducibility of both estimation methods are presented.