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This paper describes a method to measure the rocking motion of lab-scale armour units. Sensors as found in mobile phones are used. These sensors, data-storage and battery are all embedded in the model units, such that they can be applied without wires attached to them. The technique is applied to double-layer units in order to compare the results to the existing knowledge for this type of armour layers. In contrast to previous research, the gyroscope reading is used to determine the (rocking) impact velocities. Two pioneer measurement series are described. From the readings both the temporal distribution of rocking can be inferred, as well as the spatial distribution. The temporal probability distribution for the rocking events seems logarithmic, with the impact velocity u2% being in the same order of magnitude as those reported earlier. These measurements indicate that for a randomly placed cube in an armour layer most rocking and most violent impact velocities occur about 2Dn under the waterline, instead of around the waterline. Moreover, the wave steepness is seen to have an effect on the rocking intensity. From the measurements with multiple units it can be seen that the measured impact velocity exhibits a large spatial variation among different units at an otherwise equal location., Hydraulic Structures and Flood Risk

This paper describes a method to measure the rocking motion of lab-scale armour units. Sensors as found in mobile phones are used. These sensors, data-storage and battery are all embedded in the model units, such that they can be applied without wires attached to them. The technique is applied to double-layer units in order to compare the results to the existing knowledge for this type of armour layers. In contrast to previous research, the gyroscope reading is used to determine the (rocking) impact velocities. Two pioneer measurement series are described. From the readings both the temporal distribution of rocking can be inferred, as well as the spatial distribution. The temporal probability distribution for the rocking events seems logarithmic, with the impact velocity u2% being in the same order of magnitude as those reported earlier. These measurements indicate that for a randomly placed cube in an armour layer most rocking and most violent impact velocities occur about 2Dn under the waterline, instead of around the waterline. Moreover, the wave steepness is seen to have an effect on the rocking intensity. From the measurements with multiple units it can be seen that the measured impact velocity exhibits a large spatial variation among different units at an otherwise equal location., Hydraulic Structures and Flood Risk

Rocking behavior of breakwater research was conducted by Centre for Civil Engineering Research and Codes workgroup CUR C70 (1989) and after that no further validation of the research work has been done. In order to understand the rocking behavior and validate the previously conducted research CUR C70 (1989) wave flume test has been conducted in similar setup. One of the important parameter of rocking behavior is the magnitude of impact velocity and the distribution of this impact velocity stochastically and spatially. This research investigates the order of the magnitude of the impact velocity and distribution of the impact velocity comparing, validating and concluding new findings those were not incorporated in CUR C70 (1989) research. During this research a new type of sensor Tinyduino has been used inside a cube to measure the acceleration and angular velocity of the cubes. Eight of these sensors were used in eight different cubes. All the sensors were tested properly in Deltares to check the sensors working properly and better understanding the sensors. Before this research two test programs were performed by Deltares in tetrapod in double layer using this Tinyduino sensor in stand alone mode but the data were not analyzed. This research analyzed the data for the tetrapods provided by Deltares and compared with CUR 70 (1989). During this analysis and the testing of the sensors it is found that angular velocity measurement can be much more reliable than acceleration hence the angular velocity measurement is used during data processing of instrumented cubes in double layer. For experiments eight instrumented cubes were placed using very flexible wire in a randomly placed double layer cubes with same size and almost similar density over a permeable filter layer. The slope 1:1.5 is used for the experiment same as the CUR C70 (1989) research conducted. The cubes were placed in one constant level but the water level is varied in order to demonstrate, Coastal and Marine Engineering and Management (CoMEM)

Rocking behavior of breakwater research was conducted by Centre for Civil Engineering Research and Codes workgroup CUR C70 (1989) and after that no further validation of the research work has been done. In order to understand the rocking behavior and validate the previously conducted research CUR C70 (1989) wave flume test has been conducted in similar setup. One of the important parameter of rocking behavior is the magnitude of impact velocity and the distribution of this impact velocity stochastically and spatially. This research investigates the order of the magnitude of the impact velocity and distribution of the impact velocity comparing, validating and concluding new findings those were not incorporated in CUR C70 (1989) research. During this research a new type of sensor Tinyduino has been used inside a cube to measure the acceleration and angular velocity of the cubes. Eight of these sensors were used in eight different cubes. All the sensors were tested properly in Deltares to check the sensors working properly and better understanding the sensors. Before this research two test programs were performed by Deltares in tetrapod in double layer using this Tinyduino sensor in stand alone mode but the data were not analyzed. This research analyzed the data for the tetrapods provided by Deltares and compared with CUR 70 (1989). During this analysis and the testing of the sensors it is found that angular velocity measurement can be much more reliable than acceleration hence the angular velocity measurement is used during data processing of instrumented cubes in double layer. For experiments eight instrumented cubes were placed using very flexible wire in a randomly placed double layer cubes with same size and almost similar density over a permeable filter layer. The slope 1:1.5 is used for the experiment same as the CUR C70 (1989) research conducted. The cubes were placed in one constant level but the water level is varied in order to demonstrate, Coastal and Marine Engineering and Management (CoMEM)