Improved hydraulic forest boom end-effector acceleration control to counterbalance the gravitational load force in horizontal timber cutting using actuator redundancy

摘要

This paper concentrates on the forest machines, which are working in the cut-to-length method. The study deals with the boom lowering function, which is a potential solution to avoid cutting damages during the timber cutting process. The purpose is momentarily to counterbalance the gravitational force of a log in horizontal timber cutting. The analysis is carried out in actuator coordinates so as to make the results usable in control schemes with actuator position feedback. In this study redundancy resolution of hydraulic forest boom is considered. Three different pseudoinverse-based redundancy resolutions are presented and compared in terms of hydraulic parameters. The first redundancy resolution is unweighted (minimum sum of squares of actuator velocities), the second and third are weighted (minimum kinetic energy) and (minimum load flow norm). Simulations of a typical task with the proposed method show that minimizing the actuator load flow yields the best results. The improvement of the boom lowering function is a part of the research project, which is aimed to improve timber cutting efficiency in a single-grip harvester.