High Precision Robotic Navigation and Sensing Jiazhe Tang Dr. Rodrigo Aviles-Espinosa Dr. Elizabeth Rendon-Morales jt558@sussex.ac.uk e.rendon-morales@sussex.ac.uk r.aviles-espinosa@sussex.ac.uk School of Engineering and Informatics, University of Sussex, Brighton, UK Machine vision system for quantification of aortic and pulmonic valvuloplasty catheter compliance Reference [1] F. C. A. Groen, I. T. Young, and G. Ligthart, ‘A comparison of different focus functions for use in autofocus algorithms’, Cytometry, vol. 6, no. 2, pp. 81–91, Mar. 1985, doi: 10.1002/cyto.990060202. [2] University College London, China et al., ‘Valvuloplasty Balloon Catheter Sizing Approach for Calcified Aortic Valve with Different Annulus Ratios’, in Proceedings of The 15th Hamlyn Symposium on Medical Robotics 2023, The Hamlyn Centre, Imperial College London London, UK, Jun. 2023, pp. 37–38. doi: 10.31256/HSMR2023.19. [3] X. Huang, E. Rendon-Morales, and R. Aviles-Espinosa, ‘ROMI: Design and Experimental Evaluation of a Linear Delta Robotic System for High-Precision Applications’, Machines, vol. 11, no. 12, p. 1072, Dec. 2023, doi: 10.3390/machines11121072. Introduction Research Gaps Experiment Methods & Results Balloon aortic valvuloplasty (BAV) is a simple and low-cost treatment for patients with severe aortic stenosis, for aortic valve replacement and to select the proper transcatheter heart valve (THV) size. During THV implantation choosing the correct balloon size is paramount to reduce the risks of coronary occlusion, annular damage or THV embolization. In this research, we present a non-contact metrology system for BAV measurement based on a high precision robotic system equipped with a five elements brightfield microscope system. The robot is controlled though a custom-made GUI operated though an FPGA. The balloon initial diameter is determined optically. Upon ballon inflation, the defocused image is then refocused though passive focusing algorithms used to identify the best focal position. Current methods for selecting the proper balloon dimensions are based on transoesophageal echocardiography and computed tomography all these requiring exposing the patients to high doses of radiation [1]. Moreover, the images require to be analysed by specialized staff. Alternative methods propose the use of BAV to determine the correct THV size using a sterile calliper [2]. This, being a contact-based measurement may compromise the measurement accuracy. Sterile Calliper [2] ROMI [3] Transoesophageal Echocardiography Computed Tomography [1] Each focus evaluation function has its own array of scores. We normalize each of these arrays individually and then plot the results. Balloon with 1 Atmosphere, All Focus Methods Test Results Conclusion • Current results considering algorithms such as the Absolute Tenengrad based on image differentiation, Vollath‘s F4 based on correlation measurement, and Normalized Variance based on statistics, shows that the selected focus algorithms are able to converge at the same focal position. • It allowing for a fast and precise BAV balloon calibration with sub-millimetre accuracy <10 um showing the potential of the here presented work to be used in medial settings to automate preoperative balloon characterization. • Future work will focus on measuring the initial size of the balloon, and according effective passive automatic focus method to determine the change of the size of the balloon. Balloon with 1 Atmosphere, Effective Focus Methods Test Results Not Focused Focused • Set initial position. (Position C) • Down to position A. • Start autonomy moving. • Go to A, go to B, then go to A. • It should pass the best focus point twice, which will give back two peak on the results of the focus evaluation function diagram.