RESUMO
Objective To propose a new multi-joint series venipuncture system, explore the mechanics and kinematics-based related control problems involved in needle insertion and needle picking during the puncture process, and verify feasibility of this system. Methods A puncture manipulator was built, and needle displacement control algorithm was proposed by combing with the puncture mechanics model. The the forward kinematics was calculated by using DH method, so as to obtain the tip coordinates. Then the inverse kinematics was calculated by using the geometric method. The forward and inverse processes were closely connected. The position error of the end coordinates before and after needle picking was compared by using the method of kinematics positive solution-inverse solution-re-positive solution. Finally, experimental verification and simulation were conducted by combining with the physical object. Results Through simulation and experiments, accuracy of the theoretical model was verified. The needle insertion algorithm could be used to achieve success with only one needle insertion, which provided theoretical basis for the control of robot arm. The position error before and after needle picking could be controlled within 1 mm from the end trajectory. The end needle tip of robot arm was almost kept fixed during the needle picking process. Therefore, this needle picking scheme was feasible and could basically verify that the needle picking action of robot arm met the accuracy and safety requirements. Conclusions The venipuncture manipulator truly simulates the needle insertion and needle picking action during the puncture process, and can safely and accurately realize the needle insertion and needle picking action with needle tip as the fixed point, indicating that it has certain clinical value.
RESUMO
Objective To obtain a more suitable puncture method for venipuncture robot through experiments.Methods By using different puncture speeds and angles for biomimetic materials, the force-time curves by various puncture methods were obtained. Results During puncture process, with the increase of the puncture angle, a smaller puncture force was required. The faster puncture speed would lead to a larger puncture force. Conclusions The 40°-45° puncture angleand the 120-300 mm/min puncture speed should be used for designing the puncture method of venipuncture robot. The results provide references for selecting the puncture angle and speed of the venipuncture robot.
RESUMO
Objective To design and develop an in vitro simulation device for circumferential stress of mural coronary artery, so as to achieve the in vitro loading of mural circumferential stress under coronary myocardial bridge oppression with different degrees. MethodsUsing the in vitro simulation device for myocardial bridge coronary artery hemodynamics, the in vitro measurement of mural circumferential stress was achieved. Based on the experimental data, the in vitro loading of mural circumferential stress under coronary myocardial bridge oppression with different degrees was achieved. Results The in vitro measurement experiment showed that the maximum, average and fluctuation of circumferential stress at proximal end of mural coronary artery would increase significantly with the increase in the degree of myocardial bridge oppression. The in vitro loading experiment of mural circumferential stress verified that the loading waveform coincided basically with the experimental waveform from in vitro measurement. Conclusions The device could realize the in vitro loading of mural circumferential stress, which provided an in vitro simulation platform which was as close as possible to the in vivo environment, so as to explore the influence from hemodynamic abnormality of proximal mural coronary artery on the occurrence of atherosclerosis and plaque rupture.