NEWS Semi-automation functions applied for forwarder cranes will improve operator performance, while vibration reduction can increase operator comfort. Szabolcs Fodor defends the results in his thesis at Umeå University on the 27 October.
Szabolcs Fodor besides the crane prototype. Photo: Ismael Castillo
Forests provide the main supply of wood, that is renewable, reusable and recyclable raw resource, which is needed for our everyday life. To carefully exploit these resources, advanced heavy-duty machines are used in the process, such as forwarders. A forwarder is a forestry vehicle that collects and carries logs from the harvesting site to the road side. To perform this operation human operators are trained to manually control a robotic arm, crane, that is mounted on the forwarder. However, this task is not easy, is mentally demanding and most of the times affects operator productivity.
The first part of my thesis deals with semi-automation functions, meaning execution of automatic motions of the crane that are initiated by the operators. Basically, during the automated motions the operators can rest or focus on other aspects of the crane manipulation. Mostly, Szabolcs Fodor used techniques from conventional robotics and control theory field and adapted them to fit into the semi-automation context of the forwarder crane.
“The advantage of the methods and techniques that were developed consists in their simplicity and practicality, but also suggest easier application for real forestry machines,” says Szabolcs Fodor.
In the second part of the thesis Szabolcs Fodor studied the effects of vibrations created by lifting and lowering motions of the crane in the vertical plane. On one hand these vibrations are the result of aggressive operator commands that also cause discomfort in the cabin, and on the other hand introduce wear, which reduces the lifetime of the main lift cylinder. These vibrations are reduced with active vibration damping methods, meaning that designated sensors actively monitor the magnitude of the crane oscillations and an electronic control system uses this information to introduce additional energy to the input control signal to reduce the vibrations.
All of the proposed methods and techniques were experimentally verified on a forwarder crane prototype to test their feasibility. It is available at the Department of Applied Physics and Electronics.
Szabolcs Fodor is from Transylvania, Romania. He holds a Dipl. Ing. Degree in Automation and applied electronics from SHUT (Sapientia – Hungarian University of Transylvania) and Bsc in Computer Science from Petru Maior University.
Friday 27 October, Szabolcs Fodor at the Department of Applied Physics and Electronics, Umeå University, defends his thesis entitled Towards semi-automation of forwarder cranes: automated trajectory planning and active vibration damping.
The public defense will take place at 13.00 in room N420, 4th floor, Naturvetarhuset, Umeå University.
Faculty opponent is Professor Torben Ole Andersen, Institutionen för Energiteknik, Hydrauliska och Mekatroniska System, Aalborg universitet, Aalborg, Denmark
Szabolcs Fodor, the Department of Applied Physics and ElectronicsTelephone: +46(0)72-563 94 80
Email: szabolcs.fodor@umu.se
Editor: Ingrid Söderbergh