Conversion mechanism for solving the end-stop problem of hydraulic power take-off system for wave energy

End-stop problem is a critical issue in the hydraulic power take-off (PTO) system. This paper focuses on studying the conversion mechanism of the hydraulic PTO system of the proposed multi-body articulated wave energy converter (WEC), which aims to address the end-stop problem. Taking into consideration the working requirements of the proposed WEC as the constraint condition, the single compound hinge type swing cylinder 6-bar mechanism is designed as WEC's hydraulic PTO conversion mechanism. The movement and dynamics of the mechanism is analyzed, and its parameter optimization mathematical model is established. By integrating software ADAMS and MATLAB with iSIGHT, the optimal design of the mechanism is realized by using a pointer automatic optimizer. The results show that the hydraulic cylinder can avoid the end-stop problem in extreme conditions. Furthermore, it can also make full use of its effective stroke to improve the energy conversion efficiency. Finally, the operational performance of the hydraulic PTO system is validated by sea trials.