This master’s thesis is an exploration of force feedback in offshore applications with the intention of teleoperating heavy machinery. Specifically, Allseas provided their field joint coating machine handling for offshore pipelay as the subject and scope of this study. The anti-sway use case is identified through literature research, user and expert interviews, and observation of machine handling. Due to the nature of offshore dynamics coupled with heavy machine movement, sway of these machines is relevant to all specifics of handling and placing the machine on the pipe.

Operators rely on their intuition and experience when manually operating these machines. For the proposed teleoperation of machine handling, the operator is now distanced from the machine, removing their sense of control, direct force contact, and now making them trust in automation. This is where a force feedback telemanipulator can increase situational awareness and human machine performance. This is achieved through returning the direct contact forces back to the operator and providing them intuitive control from afar. With more research, rapid prototyping, and machine simulation, Paddy (the teleoperation force feedback test set up) is designed and developed. The proof-of-concept test set up is built using open-source frameworks such as Stanford Hapkit and Vanderbilt Simulink model, but with substantial redesign for offshore anti-sway use case.

To validate the design and use case, a user test with 12 Allseas engineers is conducted. The task is to mitigate the swing of the FJC simulation via the handheld manipulator with and without force feedback. The results imply that the main hypotheses are valid: (1) force feedback yields faster stabilization times, (2) the perceived workload from NASA-TLX scores is lower for force feedback (3) the user requirements and ease of use UMUX-Lite scores is favourable with force feedback, and (4) embodiment and hand placement influences expectations and feeling the feedback mechanisms. Future research could explore different feedback types (assistance vs. error prevention), feedback basis (sway angle vs. angular velocity) or further confirm these hypotheses.

Force feedback is not typically studied in industrial engineering. Thus, design guidelines are created based on this thesis exploration, emphasizing that force feedback is not an add on, but should be considered from the start of the design process. Lastly, recommendations for force feedback in Allseas and other relevant applications are stated for increased situational awareness, task efficiency, and enhanced HMI.

Wire rope slings are commonly used lifting tools in all sorts of engineering applications. Usually, slings are either loaded axially or they are bent around a load bearing element such as a shackle or pipe. In the latter case, the combination of bending and axial loading introduces additional stresses within the wire rope that cause a reduction in capacity. In the offshore industry, this reduction is currently taken into account using a safety factor recommended by standardization societies such as DNVGL and IMCA. However, the expression to derive this factor solely depends on the rope’s curvature around the bend. Given that steel wire ropes can come in many different geometric configurations and their behavior is nonlinear, it is questionable to assume that this reduction is only based on a single parameter. Consequently, the main research question of this thesis is:

How does the wire rope capacity reduction due to forced bending recommended by DNVGL and IMCA standards compare to analytical and experimental results obtained for wire ropes of different sizes and configurations?

The approach to answering this question starts with a literature study, creating a predictive analytical model and then performing experiments for validation. Findings from the literature study uncover the main parameters affecting wire rope behavior such as lay angles, wire diameters and stress-strain relations. With these insights, an analytical model is created to predict the reduction in capacity of steel wire ropes subjected to forced bending. The model analyzes individual wire behavior and then applies a failure criterion to determine when the entire rope cross-section would fail. Finally, small and full-scale experiments are conducted that test different rope configurations (6x25F-IWRC & 6x36WS-IWRC) with different rope sizes (∅20 mm & ∅77 mm).

Knowledge gained from the literature study, the analytical model and the experiments was combined to come up with conclusions pertaining to the main research question. It was found that rope configurations, specifically wire to rope diameter ratios, played a vital role in the capacity reduction of steel wire rope slings. Additionally, results indicate that the capacity of slings increases with higher lay angles. The results also indicated that expressions recommended by the standards are not conservative enough for certain curvature ranges and ropes. Building on the research question, several observations pertaining to rope ovalization and consistency of failure location raised ideas for further investigation.