Model tests with submerged bodies are routine work at SVA Potsdam. The measurements are carried out with full scale objects and scaled models. The range of testing objects covers submerged vessels like ROVs, AUVs and submarines as well as submerged propulsion systems like podded drives and waterjets. Moreover rather “exotic” cases like marine animals and divers can be measured.
Generally, the main objective of the analyses is the measurement of forces with these objects. Beside the static resistance forces, lateral forces resulting from oblique inflow and the effects of steering devices are of special interest. Likewise, measurements of static forces acting upon self driven systems can be provided. For systems identification of submerged bodies forces measurements even of captivated, self driven models can be performed. Moreover the motions of a free running model that is sailing down a computer controlled course can be analysed. Even wake field measurements of submerged bodies can be executed. With these systems the measurement point is located outside the model and above the water surface. The 3- or 6-components force balances vary with respect to measurement range and sensitivity.
The most flexible and thus the optimal device for the measurement of submerged objects is the SUBPMM (SUB Planar Motion Mechanism) system.
Regarding submarines special attention is laid upon the determination of motion behaviour. With the SUBPMM device the movement in a second plane can be superposed onto the towing direction. Thereby all model motions and the coefficients for the equations of motion can be retrieved. One special feature of the SUBPMM is the location of the measurement point inside the model; this way the influences of the towing gear can be eliminated! The SUBPMM can be utilized for models of 1 - 6 m and depths of 0.5 - 2.5 m. The propulsors are driven by encapsulated modules of different sizes, combining motor and dynamometer. The fins are controlled by encapsulated servo drives.
Free running submerged vehicles can also be run autonomously.
To this end an encapsulated computer is installed onboard the model. According to a given program the drives and fins are controlled by the computer, keeping the vessel on its course.
