Research On Human Grasp Movement Analysis And The Postural Synergy Anthropomorphic Hand

Human hands can accomplish a variety of grasp tasks in daily life.The complexity,variety of the tasks and the complex biological structure of human hand make people understand the grasp movement challenging,which restrict the development of the anthropomorphic robotic hand.For designing an anthropomorphic hand,people hope that the anthropomorphic hand can reconstruct the human grasp movement characteristic by a simplied mechanism and control system with an anthropomorphic appearance.Therefore,for further understanding the human grasp movement and simplying the mechanism and control system,this paper focus on the analysis of human grasp movement,reconstruction of the human grasp characteristic and simplification to the mechanism and control system of the anthropomorphic hand via postural synergy,and design of the postural synergy anthropomorphic hand,the main research contents are as follows:In order to understand the human grasp movement clearer and more systematic,the analysis starts from the human hand movement functionality and gradually refines to the grasp movement.Based on the hand action,a hierarchical tree is built according to the previous significant definitions of hand movement classification and the action goal.The hand action is decomposed into prehensile and non-prehensile class contained 9 sub-classes.The human prehensile functionality is further studied.A prehensile taxonomy is constructed for exploring the influence factors of human grasp postures.The analysis result shows that the object shape,size and relative positions with human hand are the major influence factors leading to the prehensile diversity.After considering all three influence factors,a human grasp posture capture system is built and a human tolerance grasping dataset is constructed.Compared with the other two traditional grasp posture datasets,the experimental results show that the tolrrance grasp dataset can represent the human grasp functionality more comprehensively.Human grasp movement is analyzed based on the constructed human tolerance grasping data set.The basic statistic is presented for understanding the distribution characteristic of each joint angle.A joint movement correlation analysis method is proposed.Firstly,the correlation analysis to each joint is presented.Then,the correlation analysis between fingers and between joints are separately carried out for a better application.Analysis of variance is used to analyze the influence of the object shape,size and relative position to the thumb and four-finger grasp postures.As it is difficult for human to control each hand joint independently,the jo int movement independence is defined and quantified through correlatioin coefficient,variance and information entropy of the joint angle.Finally,an EMG based experiment is presented for verifying the independence quantification results.In order to meet both the appearance and functionality anthropomorphism requirements of anthropomorphic hand design,a synthetic framework is constructed for evaluating the anthropomorphism with 12 anthropomorphism indexes,and the piecewise function and index matrix quantified evaluation methods are proposed.The anthropomorphism of seven representative prosthetic hands is quantified and evaluated.The correlation analysis is carried out to the evaluated results of each index,and the design priority of anthropomorphism indexes is obtained.Whether from the view of the quantified evalution results or design priority,the actuation configuration always should be considered with a high priority.Therefore,based on the human grasp movement analysis results of chapter 3,the actuation configuration strategies are proposed and the module-devision actuation configuration is built.For further simplifying the mechanism and control system,the postural synergy is applied to actuation modules of four fingers.The number of actuators and control dimensionality are reduced.Finally,the mechanical implementation performance is evaluated,so as to lay the foundation for both the actuators and the mechanism to be embedded in the palm.As postural synergy mechanism size is always large and the structure is not compact enough,the mechanism is miniaturized and able to be embedded in the palm with a compact sturcture,an inter-module postural synergy hand is built.Based on the module-division actuation configuration of four fingers,the mechanism and arrangement are both determined.For further miniaturizing the implemented mechanism of postural synergy,synergy matrix is decomposed,and the MCP and PIP joint motions are decomposed into proportion motion,transmmition chain motion and differential motion,mechanically implemented by the pulley,gear transmission chain and planetary gear differential mechanism.The finger is designed,and the MCP and PIP joint can be separated actuated by tendons.Finally,the characteristic reconstruction experiment of postural synergy basis,posture reconstruction experiment and object grasp experiment are presented to verify the performance of inter-module postural synergy hand.The experimental results show that the postural synergy hand can perform the postural synergy basis characteristic of human hand,reconstruct the Feix grasp taxonomy with a diversity of grasp postures and grasp different objects successfully with a simple control manner.