Inference about Transient States of Innovative RCM Structure for Soft Tissue Surgery Using FEM Taking into Account Inputs from in Vitro Experiment on Cardiovascular Tissue

-Surgical robots with the RCM mechanical systems are used clinically in such areas of surgery as: laparoscopy, heart surgery and urology. Transient state analysis using the FEM method of the innovative surgical robot structure based on the RCM mechanism with four degrees of freedom was performed. Such the mechanism enables the movement of the constant point, which extends its possibilities in relation to classic constant point mechanisms used in hospitals. The mesh computational model enables determination of: stresses, displacements and strains during transient analysis based on the von Mises hypothesis. Experienced cardiac surgeon performed in vitro experiment on cardiovascular tissue using endoscopic instruments for positioning and tissue incision activities. The trajectory of endoscopic instruments was determined using four optical CMOS sensors. A problem of the endoscope position was solved using APAS software and DLT algorithm. The Savitzky - Golay polynomial smoothing was used to filter a signal from the random component. The width of the numerical window for the SG procedure was determined based on the Durbin-Watson formula. Values of stresses related to the safety factor, displacements related to the positioning accuracy and repeatability as well as strains determining a susceptibility of the surgical robot structure were obtained. On their basis, the safety factor was determined and it was found that from the point of view of its value, the structure is safe in relation to the analysis of transient states. The work made it possible to observe and evaluate the stress values and the susceptibility of the structure of the surgical robot during the analysis of transient states, taking into account inputs that occur during cardiac surgery.