By analyzing the physiological structure and motion characteristics of human ankle joint, a four degree of freedom generalized spherical parallel mechanism is proposed to meet the needs of ankle rehabilitation. Using the spiral theory to analyze the motion characteristics of the mechanism and based on the method of describing the position with spherical coordinates and the posture with Euler Angle, the inverse solution of the closed vector equation of mechanism position is established. The workspace of mechanism is analyzed according to the constraint conditions of inverse solution. The workspace of the moving spherical center of the mechanism is used to match the movement space of the tibiotalar joint, and the workspace of the dynamic platform is used to match the movement space of subtalar joint. Genetic algorithm is used to optimize the key scale parameters of the mechanism. The results show that the workspace of the generalized spherical parallel mechanism can satisfy the actual movement space of human ankle joint rehabilitation. The results of this paper can provide theoretical basis and experimental reference for the design of ankle joint rehabilitation robot with high matching degree.
Objective To summarize the research progress of copper and its derivatives in gastrointestinal tumors in recent years, aiming to provide reference for clinical diagnosis and treatment decisions. Method The literatures related to copper homeostasis and copper death in recent years were read and summarized, and the research progress on the role of copper in cancer and copper applications in cancer diagnosis and treatment was reviewed. Results Copper was an essential trace element involved in a variety of basic biological processes. Elevated levels of copper in serum and tissues were associated with the development of tumors. As the mechanisms of copper action in various gastrointestinal tumors were being investigated, the use of copper and related derivatives in the treatment of cancer patients had become a new strategy. Conclusion Copper and its derivatives have a promising future in the treatment of gastrointestinal tumors, but their benefits in clinical patients still need to be demonstrated in numerous clinical trials.