This comparative study shows the behaviour of 3 different controllers used to perform an automatic robotic ultrasound scan of breast tissue. Performing automatic US scans has several advantages such as reducing variability between doctors, the possibility of keeping a constant deformation or repeating a US scan multiple times without having very variant results.
To perform an automatic scan, a predefined trajectory is given to a 7DoF robot. However, this trajectory does not ensure contact of the US transducer with the breast, therefore, the trajectory has to be adapted in real-time to ensure contact. To do so, a force controller, a US image-based controller and a hybrid force-image controller have been implemented and tested in 3 different hardness phantoms.
The force and hybrid controller makes use of a calibrated force sensor to ensure a constant contact force with the tissue. The image-based controller uses a confidence map to ensure that a desired percentage of the US probe is in contact with the tissue. Furthermore, the hybrid and image controller ensures that the US probe is normally oriented to the tissue.
The results are analysed to determine which controller is the optimal for automated robotic US scan of breast tissue, and possible applications in different body tissues.