Bionic Attitude Transformation Combined with Closed Motion for a Free Floating Space Robot

In order to realize the small error attitude transformation of a free floating space robot,a new method of three degrees of freedom（ DOF） attitude transformation was proposed for the space robot using a bionic joint. A general kinematic model of the space robot was established based on the law of linear and angular momentum conservation. A combinational joint model was established combined with bionic joint and closed motion. The attitude transformation of planar,two DOF and three DOF is analyzed and simulated by the model,and it is verified that the feasibility of attitude transformation in three DOF space. Finally,the specific scheme of disturbance elimination in attitude transformation is presented and simulation results are obtained.Therefore,the range of application field of the bionic joint model has been expanded.

Numerical study on transom stern ventilation and resistance of high-speed ship in calm water

A transom stern is a common design feature for a high-speed ship.In the present study,the transom stern ventilation of NPL 3b,5b hull is investigated by three methods:H−H formula,Doctors’formula,and computational fluid dynamics(CFD)method at first.For the CFD method,the ratios of the wave elevation and wetted area are used to determine the transom ventilation.Comparisons of results show that Doctors’formula is more accurate to calculate the critical transom draft Froude number.And then a Rankine panel method(RPM)based on the high-order boundary element method incorporated the modified transom stern condition is implemented to evaluate the steady wave problem of a high-speed fishery patrol ship in calm water.Besides,free-surface(FS)and double body(DB)simulations based on Star-CCM+are carried out to obtain the wave-making resistance and total resistance.The results of the resistance and wave pattern around the fishery patrol ship computed by RPM show generally good agreement with experimental measurement and CFD results.Numerical results indicate that the developed Rankine panel method with transom condition could predict the resistance of high-speed displacement ships with good accuracy.