Elham Kowsari ^1* Reza Ghabcheloo ²

• ¹ Postdoctoral research fellow, Tampere, Finland
• ² Tampere University, Tampere, Pirkanmaa, Finland

In this paper, we propose a novel optimal feedforward controller for Hydraulic manipulators equipped with a passive grapple, which tends to sway during and after movement. We apply this strategy to a forwarder machine featuring a passive grappling mechanism commonly used in forestry for log-loading tasks. The proposed optimal feedforward controller is notable for its smooth operation, low computational demands, and efficient damping sway. It proves especially effective and versatile, even in initial sway, highlighting its robustness. The controller's computational efficiency and reduced hardware needs make it a cost-effective sway control solution. Additionally, by adjusting the parameter of the cost function defined here, the performance can be customized according to the operator's preferences. It has been implemented using the Amesim model of a forwarder to evaluate the proposed controller. Simulation results for two different forwarder movements show a significant reduction in sway motions, with an average decrease of more than 60%. This improvement is achieved without extra sway-detection sensors, simplifying the design and cutting costs. Moreover, our method's versatility and broad applicability suggest its potential across various fields. It provides a new framework for designing anti-sway controllers for construction cranes, forestry vehicles, aerial drones carrying slung loads, and other robotic manipulators with passive end-effectors. This adaptability paves the way for developing customized anti-sway motion control systems, promising significant advances in safety and efficiency.