Research On Design And Control System Of Flexible Dexterous Hand Based On C-shaped Joint

With the expanding application of robots in the fields of service and healthcare,the demand for dexterous manipulation of objects is increasing.As a key component for achieving dexterous manipulation in robots,a dexterous hand has the characteristics of high flexibility and strong operational capability.Its application in national defense,healthcare,rescue,aerospace,and industrial production is of great significance.Therefore,the development of a low-cost,practical,multi-fingered,and flexible dexterous hand that can be applied to a variety of object grasping and manipulation has become a key issue and research hotspot in the field of robot dexterity,with broad application prospects.This paper designs a flexible dexterous hand based on a C-shaped joint,and conducts in-depth research on the C-shaped joint,structural design,kinematics,motion space,and control system of the flexible dexterous hand.Simulation and experimental verification are also completed.Firstly,this article analyzes the physiological structure and grasping patterns of the human hand and proposes a new finger joint design with bi-directional stiffness,namely the C-shaped joint.Based on the C-shaped joint,the design of the five fingers of the flexible and dexterous hand is completed.On the other hand,considering the needs of the service and medical industries,the design of the thumb and little finger’s swinging structure and the adhesive palm structure are conducted,which endows the dexterous hand with higher degrees of freedom.Relevant transmission and drive schemes are also designed.Secondly,the C-shaped joint is theoretically analyzed using the bending member theory and the thin shell theory.The equations of the bending moments in forward and reverse directions are derived,and simulation analysis and finger joint bearing experiments are conducted using finite element methods.The maximum stiffness in the reverse direction is found to be 36 times that in the forward direction.Based on the D-H parameter method,the forward and inverse kinematics of the dexterous hand are calculated and analyzed.MATLAB is used to obtain the workspace of finger motion and to derive the Jacobian matrices between the fingertip and each joint,as well as the relationship between the joint velocity vector and the generalized velocity vector of the fingertip.Thirdly,the control system of the dexterous hand is built.The selection of actuator components and the design of the pneumatic system are completed.The hardware circuit and software system of the control system are introduced.The control system adopts a combination of upper and lower computer control modes and has the advantages of simple operation,convenience,reliability,and stability.Finally,the experimental testing platform of the dexterous hand is established.Gesture action experiments,finger support experiments,palm adhesion experiments,and little finger swing experiments are conducted to verify the reliability of the design of each part of the flexible and dexterous hand and the stability of the control system.Ten physical grasping experiments and multitasking grasping experiments are then conducted,and the results show that the dexterous hand has high degrees of freedom,high dexterity,and simple,convenient,and reliable operation.Furthermore,the practicality of the dexterous hand based on myoelectric signals is validated.Firstly,the myoelectric signals and SEMG acquisition system are introduced,and relevant interactive operation experiments are conducted.The experimental results show that the average recognition rate of the three hand gestures based on myoelectric signals is above 90%,and the myoelectric-based dexterous hand has broad application prospects.