Research And Manufacture Of Variable Stiffness Soft Humanoid Finger Based On Lmpa

Soft robotics is a new research area in robotics.The adaptability and adaptability of its structure and materials have compliant interaction and high adaptability,which makes up for the deficiencies of rigid robots to some extent.Soft manipulators have become an important branch of research with its wide applicability.The soft manipulators are made of soft materials with unlimited degrees of freedom.Their dexterous structure and high flexibility of the material bring about problems of large nonlinear deformation and passive deformation.The human finger has a flexible bending grip and has a variable stiffness feature.According to the structure and function of the human finger,an articulated flexible human finger with variable stiffness was proposed,and its design,manufacturing,kinematics modeling,pneumatic control and prototype experiments were studied.First,articulating human fingers are developed based on fiber-reinforced actuators.By referring to the size,shape and movement characteristics of the human finger,the metacarpophalangeal joints are independently driven,the two finger joints use the same drive,and the articulation effect is achieved by limiting the extension actuators on one side;Variable stiffness is achieved by embedding a low-melting alloy,and the overall stiffness is changed by changing the temperature between the solid and liquid phases.Second-order Yeoh model is used to analyze the structural parameters that affect bending angle through ABAQUS finite element techniqueSecondly,for the problem that the nonlinearity of the superelastic flexible material causes the modeling of the soft humanoid finger movement difficult,the virtual work principle is used to solve the problem of elastic strain energy and air pressure for virtual work.The elastic strain energy density function is used to calculate the energy stored in the entire deformation,and the kinematics relationship between the bending angle and the driving air pressure is established;the parameters in kinematics are determined by linearizing the experimental data.The accuracy of the kinematic model was verified through experiments.A soft humanoid finger was prepared using a 3D printing mold step casting process.Again,the soft body finger control system is designed for the characteristics of the soft-driven air pressure.Through the Ethernet communication and CAN bus control stepper motor to adjust the charge and discharge mechanism,using PID control algorithm to achieve closed-loop control based on air pressure feedback,air pressure,charge and deflation speed and flow continuously stable adjustable control.The control system has very good scalability and modularity.Based on the QT library and the VS2010 development platform,a host computer interface and a drive control system were programmed to perform motion control on the humanoid finger of the soft.Finally,the expansion and deflation mechanism was set up to build a multi-channel pressure control platform for prototype experiments of soft fingers.A soft finger bending angle measurement platform was designed and built,and the bending angle,hysteresis,bending performance,bending moment,stiffness,and single finger load characteristics were measured.Assembled the soft to simulate the human hand and carried out the grab planning.The gesture experiment,the grabbing experiment,and the finger displacement experiment were performed respectively,which verified the flexibility,versatility,and human-computer interaction security of the humanoid finger of the soft.