Design And Performance Research Of Rigid-flexible Hybrid Robot Dexterous Hands Based On Parallel Mechanism

Since the beginning of the 21 st century,the proportion of industrial robots in industrial production is increasing,and the requirements for their performance are also improving.Due to its speciality,the common end effector of industrial robot can only complete a single and simple grasping action,which is difficult to meet the increasing complex operation requirements.As a new type of end-effector,multi-fingered dexterous hand has good versatility and adaptability in grasping,and can complete complex and diverse operational tasks.Therefore,it has important research significance and application prospect.At present,most of the multi-fingered dexterous hands are in series structure,and the driving mode is underactuated,which makes the dexterous hands have the disadvantages of poor stability and low precision.Meanwhile,the design of fort-position hybrid control is complicated and difficult.According to the above analysis,using the advantages of parallel mechanism in motion accuracy,bearing capacity and stability,this paper proposed a dexterous robot hand with parallel finger mechanism,and designed a constant force fingertip mechanism to provide a stable and reliable force environment,and greatly simplify the control algorithm.Firstly,the grasping movements of human fingers were analyzed,and the movement type needed by fingers to complete grasping was determined.Based on the Lie group theory,a humanoid parallel finger mechanism was designed,and a three-fingered dexterous hand based on the humanoid parallel finger mechanism was proposed,and the 3D modeling design was carried out.Secondly,the DOF of the parallel finger mechanism was verified,and the kinematics analysis was carried out,including the forward and inverse kinematics solutions,Jacobian matrix and acceleration matrix.Thirdly,the performance of the parallel finger mechanism was studied and analyzed.The workspace of the parallel finger mechanism was determined by using the structural parameters and driving range of the finger mechanism.The singularity pose,dexterity and statics were analyzed by using the established Jacobian matrix.Fourth,the grasping mode of dexterous hand was studied,and the degree of freedom,kinematics and space of coordinated operation of precise grasping was analyzed.By analyzing the conditions satisfying the force closure,a mathematical model for solving the initial grasping position satisfying the force closure was obtained,and the grasping position was optimized based on the stability index.Fifth,Based on the combination of positive and negative stiffness mechanisms,a constant force fingertip mechanism was designed.The force analysis of the strong grasping of dexterous hand was carried out,and the calculation model of the sum of the minimum driving moment satisfying the stable grasping was obtained.Finally,the virtual prototype of the dexterous hand was established,and the kinematics,constant force fingertips and strong grasping were simulated analysis.A physical prototype of the parallel dexterous hand was made,and the related motion and grasping experiments were analyzed.Through theoretical analysis and experimental research on the dexterous hand,it is verified that the multi-fingered dexterous hand designed in this paper has good dexterity,adaptability and carrying capacity.It has a variety of grasping modes,which can operate grasping objects.Meanwhile,the constant force fingertips can provide a stable force output environment.Dexterous hands can meet the requirements of industrial production and manufacturing.