Research On Variable Stiffness Robot Gripper And Grasping Strategy

As emerging interdisciplinary subjects continue to emerge,robotic gripper,as an important part of robotic systems,have taken on more and more complex tasks,and have put forward higher requirements for their adaptability.Compared with traditional fixed-rigidity gripper,variable-stiffness robotic gripper have the advantages of both rigid and flexible gripper,and can be adapted to a wider range of gripping tasks.At the same time,the end gripping device on the traditional mechanical arm usually has a single function and only one or few gripping postures,which makes it difficult to adapt well to different types of gripping needs.In view of this situation,this paper designs a stiffness adjustment device,and uses the characteristics of the nonlinear spring stiffness that changes with the initial compression to achieve the stiffness adjustment function.At the same time,in order to reduce the size of the equipment as much as possible,a motor reuse scheme is adopted.The original driver of the system can adjust the stiffness at a specific position,and the number of drivers is not increased when adjusting the stiffness.On this basis,the grasping posture of the human hand is analyzed,and from the perspective of function,by increasing the freedom of the palm of the hand,the robot gripper device can be designed to achieve a variety of gripping postures,which expands the gripper to a certain extent.Working scene.At the same time,using the concept of functional zoning,the two-degree-of-freedom and three-degree-of-freedom finger link structures are designed.The driver is configured according to the grip function and fine-tuning function of the finger,and the power and speed of the motor are reasonably distributed,which helps to reduce the hand.Gripper volume reduces costs.The kinematics and statics of the single finger of the gripper were analyzed,the working space was calculated and the motor position corresponding to the joint angle was calculated,and the overall structural design was finally completed.Next,the control structure of the system is designed,the stiffness switching and posture selection in the grasping process are analyzed and studied,and the fingertip force control in the grasping process is realized through the position-based impedance force tracking algorithm.Finally,an experimental platform with variable stiffness gripper was built and related experiments were carried out.The platform includes a complete mechanical structure,drive control system and corresponding control program.In the relevant experimental part,the rotational stiffness of the finger joint was measured to verify the feasibility of stiffness adjustment.Using the flexible link of the finger joint,through the control of the position,the force control of the open loop of the fingertip is realized,and after the force sensor is added,the position-based impedance force working algorithm is used to realize the force-controlled grasping.Grabbing experiments with different postures were carried out,and a design concept adapted to various gripping postures was realized.