A general framework for automatic robotic palpation

Palpation process using elastography has been studied for malign tissue localization. This technique has been applied in ultrasound and magnetic resonance imaging modalities. However, the ultrasound features make it suitable for roboticassisted systems in real-time [1], [2], [3]. The basic principle of ultrasound elastography is based on quasi-static mechanic compression of a target tissue with an ultrasound probe to obtain its elastic parameters. This parameters are generally imaged in an elastogram for visual purposes. The procedure to obtain an elastogram in hospitals is done by hand. Nevertheless, drawbacks like abrupt changes in force compression and motion stability of the hand affect the elastogram quality an sometimes ending in a wrong diagnosis. The dexterity of a robot can tackle these issues using a stable compression motion of the ultrasound probe. Very few investigations have been undertaken regarding the use of ultrasound elastography in robot-assisted procedures. These works are related to the field of laparoscopy. For example, a snake-like robot was presented in [4], where a micro ultrasound probe attached at the distal part of the robot was used to find hard lesions by palpation motion. The da Vinci surgical robot (Intuitive Surgical Inc.) was also used to obtain elastic information of a tissue of interest by controlling the motion of a laparoscopic 2-D ultrasound probe [5]. Using a similar framework, in [6] a mechanical vibrator placed on the skin of the patient was proposed instead of controlling the motion of the ultrasound probe. However, none of these works use the strain information to control the robot.