Despite the success and prospects of the robotic catheter system for the cardiovascular access, loss of vision, and haptics have limited its global adoption. A direct implication is the great difficulty posed when trying to eliminate the backlash in catheters during vascular cannulations. As a result, physicians and patients end up been exposed to high radiation for a long period of time. Existing control systems proposed for such interventional robots have not fully consider the hysteretic (backlash) behavior. In this study, a novel robotic catheter system is designed for accessing the human cardiac area through the radial vasculature, while single factor descriptive analysis is employed to characterize the backlash behavior during axial motions of the interventional robot. Based on the descriptive analysis, an adaptive system is proposed for the backlash compensation during the cardiovascular access. The adaptive system consists of a neuro-fuzzy module that predicts a backlash gap based on bounded motion signals, and contact force modulated from a modified error-based force control model. The proposed system is implemented in MATLAB and visual C++. Finally, an in vitro experiment with a human tubular model, shows that the proposed adaptive compensation system can minimize the backlash occurrence during cardiovascular access.

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In this paper, a indoor path planning algorithm is presented to obtain the shortest trajectory for the hex-rotor aircraft in the complex terrains with no-fly zones. This algorithm finds all flyable and feasible trajectories from the start point to the landmarks and from the landmarks to the destination point firstly. Then, it constructs the path network between all landmarks and connects the start point, all landmarks and the destination point. Finally, it finds the final navigable trajectory. To overcome the drawbacks of Global Positioning System (GPS) and improve the positioning accuracy, the visual navigation based on landmarks is employed to assist the Inertial Navigation System (INS). It is accomplished by comparing the corresponding position of landmarks in the real-time image and onboard stored integral referenced image. The landmarks must be visible and distinguishable. The results of simulations and actual indoor flights show that the algorithm proposed in this paper was feasible for path planning and it can be used in indoor and outdoor environments.