Design and optimization of a master-slave system for tele-echography application

This paper introduces the research carried out on the design of a robotized tele-echography system. Such a system is composed of a master control device and a slave robotic manipulator. Our objective is to contribute to the French Agence National de Recherche (ANR) project PROSIT by designing both devices. To define the kinematic architecture, we had proposed an approach based on the analysis of the expert gesture as a first step of the design process. We have used a motion capture system to study the ultrasound examination gesture and to define the kinematic specifications for the proposed manipulator. A new kind of architecture was selected: the spherical parallel mechanism (SPM). We have chosen it because it reaches the constraint requirements. The kinematic architecture was synthesized by executing a real-coded genetic algorithm (GA). We integrated optimization criteria in the synthesis of the selected architecture. We have fixed a minimum required workspace and we have chosen to optimized the SPM in terms of dexterity and compacity. Another important part of our research was to design a haptic device to provide a very intuitive control of the tele-operated robot. We have opted for a free hand interface that integrates an active force control and feedback. An Inertial Measurement Unit (IMU) has been integrated. The data collected from the IMU that we integrated are processed by a Kalman Filter. But we have modified this predictor-estimator tool from the state of art to adapt its behavior with respect to the type of motion done by the operator. Experimentations via our motion capture system have demonstrated the accuracy of this orientation control strategy. The final step will be the experimental and clinical validation on real patients.