Design And Experiment Research Of An Underactuated Hand With Rope And Pulley

Human beings rely on spacecraft for the exploration of the universe.With the development of technology,it is becoming more and more important to develop a non-cooperative objective capture device which must have the properties of simpleness,less-weight,stiffness and strong output forces.Underactuated mechanisms are studied by more and more scientists because those mechanisms can fit various outlines of target using drive sources whose number is smaller than the number of its degrees of freedom(DOF),which meets the condition above.A design scheme of a three-phalange rope-pulley underactuated robotic hand is proposed in this paper.The robotic hand can grasp object in different shapes by fitting their outlines automatically using the principle of four bar linkages motion.The 3D model is established after the dimension parameters and the types of sencors.The underactuated fingers are the foundation of grasping of the robotic hand.Analyses of single underactuated fingers is provided.The kinematics characteristics is studied by using the connections among the dimension parameters in the mechanical finger.The statics characteristics is studied by using split-bar method to gain the relationship among the output grasping forces and the input driving force.The reason of deviations between the ideal model and the actual circumstance of single finger are analysed.The prerequisite of stable capture to target is that two fingers and the object reach the force balance.The underactuated fingers can get into their stable posture adaptively by slipping along the outlines of object.The target achieves force balance and get into its stable position with two mechanical fingers enveloping movement.The stable postures of fingers and the stable areas of the target object are calculated using statics model of whole mechanical system by Matlab programs.The demo prototype is built and the calibration experiments have been made.The kinematics characteristics has been proved by measuring the speed of single finger driving by different speed sources.The statics characteristics has been proved by using single finger to envelope the objects in various shapes adaptively.The experiments of using two fingers to grasp round object to confirm finger stable posture and the objective stable area has been made.All the expe riments show the correctness of analyses.