Research On The Configuration Of The Variable Wrist-palm For A New Bionic Flexible Wrist-Hand

For the food with features of soft,tender,crisp and different shapes,robotic multi-fingered hands still can't have a flexible and stable grasp till now.Therefore,our research group put forward the concept of ‘a new bionic flexible wrist-hand',consisted of a new robotic palm,which has the ability of adaptive configuration to adjust the size and shape of the grasp space,and soft fingers to complete the grasp manipulation.Through the new robotic palm and soft fingers,the new bionic flexible wrist-hand could satisfy the grasp requirements of most food,and effectively solve the technical problems to apply the robot technology to the food industry.For the purpose of solving the problem of grasping the food with different shapes,this paper aims to design a new type of robotic palm structure through bionic research,which could adjust the grasp configuration adaptively according to the size and shape of the objects to be grasped.Furthermore,the robotic multi-fingered hands with this new palm structure,not only have a higher dexterity and workspace,but also have a better grasp quality.The main contents of this paper are as follows:First,the motion mechanism of octopus' grasping manipulation is analyzed.By casting it to a two-dimensional plane,the generalized arms-palm structure is proposed,which could be configured into any polygons of different size and shape.Based on the generalized arms-palm structure,a new bionic robotic palm structure is designed,named the variable wrist-palm,which could adjust the palm configuration adaptively according to the size and shape of the objects to be grasped,changing the fingers to the best contact points on the object,so that the robotic multi-fingered hand cloud achieve a better grasp quality.Through the configuration analysis and calculation of an example,it is proved that the variable wrist-palm could realize the adaptive configuration of any objects with different size and shape.Secondly,the overall design criterion of the variable wrist-palm is proposed.Combined with the structural scheme,the specific mechanical structure design of the variable wrist-palm is completed,including the design of the cross-rotating mechanism and the guide-translating mechanism.At the same time,the motor selection and multi-sensor configuration are completed.In addition,the actual working space of the variable wrist-palm is analyzed,proving that it could meet the size requirements of most food.Through the simulation analysis,it is proved that the variable wrist-palm has the ability of adaptive configuration of different size and shape objects.At last,a new bionic robotic multi-fingered hand with the variable wrist-palm is designed to complete grasp simulation experiments of the typical objects.Thirdly,the grasping model of the new bionic robotic multi-fingered hand with the variable wrist-palm is established.According to the force balance equation,the necessary condition to achieve the force-closure grasp for the above hand is deduced.Combined with the actual structure of the variable wrist-palm,a shape configuration planning method is proposed,which is composed of the position planning algorithm for contact points and the basic configuration determination,to determine the size of the crossing angle and the basic value of the distances between the fingers' installation center and the center of the palm.In order to achieve a higher flexibility for manipulating objects,a size configuration planning method is proposed,to determine the optimal value of the distances between the fingers' installation center and the center of the palm.Finally,a grasp example is given to demonstrate the effectiveness of the above configuration planning methods of the variable wrist-palm.