The assignment is within the scope of the TISCALI project, which is to improve the condition assessment of sewers. One of the aims of TISCALI is to develop solutions for Assessing Sewer Condition (ASC). For the quality control of concrete structures, the compressive strength is considered an important property. The Schmidt hammer is a tool that can measure the strength relatively. This tool is currently not used for assessing the sewer pipes, as it has to be operated manually. For autonomous inspection a robotic arm has to carry the hammer and place it on the surface of the pipe. A big disadvantage of the hammer is that it always has to be placed perpendicular to the surface. On top of that, the hammer always applies the same force. Besides, the method is also not fully reliable, a high repeatability error occurs.
A solution should be developed, so the robotic arm is able to measure the strength properties of the concrete pipe. This robotic arm already has sensors to be able to position itself and the robot is also able to apply certain forces. It is however unknown what accuracy is required to locate flaws in concrete. The research question is therefore stated as follows: 'To what extend can interaction between a robotic arm and the surface of a concrete pipe be used to locate structural flaws in the pipe?'
To answer this question, a robotic arm will apply an impact force on the surface of concrete samples. The concrete samples will be blocks and pipes. The elastic behavior of the concrete sample will cause a reaction force on the robotic arm, which can be measured at the joint of the arm, due to the feedback applied by the robot. An experimental setup will be designed, to test the ability to locate cracks on the concrete samples. A model of the system, the robotic arm making contact to the surface of the sample, should be designed. This model has to be able to estimate properties of material, while parameters in the model, stiffness for example, can be changed. Eventually the system should be able to apply the impact on different positions with more de rees of freedom and be able to detect cracks in the material.