• real time
• robotic assisted surgery
• teleoperation

A teleoperation system enables human interaction with environments that are inaccessible to direct human contact due to their remoteness or the presence of hazards. Recent interest in robot-assisted surgery is backed by advantages such as minimal invasiveness, enhanced accuracy and dexterity, and increased safety and reliability brought about by master/slave operations. From an engineering point of view, the main goals of teleoperation are twofold: stability and transparency. Transparency is the ability of a teleoperation system to present the undistorted dynamics of the remote environment to the human operator. In the presence of time delays, the stability and transparency of a bilateral teleoperation system are severely affected. In this thesis, two famous bilateral architectures proposed in literature (position-position and position-force schemes) are implemented in a robotic platform constituted by the slave manipulator Viper Robot and the master Phantom haptic interface, connected by an Ethernet cable and the UDP protocol. This platform is controlled by a real-time software system: RTAI. This is a real-time extension for the Linux kernel which allows to write applications with strict timing constraints for Linux. In the force-position scheme, position information is transmitted from master to slave and force information flows in the opposite direction. In the position-position scheme, the forces applied to the manipulators depend on the position difference (error) between them. To evaluate performances of teleoperation schemes implemented, we carried out various experimental tasks. Experiments were conducted on materials of different stiffness (soft sponge, polystyrene and wood), and testing needle insertions in ex-vivo bovine tissues. Finally, a statistical analysis to estimate the subjective performance of transparency and stability has been created.