| Pneumatic soft manipulators,which can effectively make up for the shortcomings of traditional rigid manipulators,have broad application prospects in the medical,agricultural picking,industrial production,and other fields due to their high flexibility,adaptability,and safe human-machine interaction.At present,the structural design,statics and kinematics modeling,driving,and control of the soft fingers are the research hotspots in the world.Based on the traditional single-cavity soft finger,this research proposes a new type of double-cavity-driven composite structure soft finger,and the following researches were carried out:(1)A new type of dual-cavity-driven composite structured soft finger was proposed,which combines the SPN(slow pneumatic network)and the FPN(fast pneumatic network)structures to improve the DOF of the traditional pneumatic soft finger,as well as its flexibility.Finite element analysis based on the Abaqus platform was used to explore the effects of key structural parameters(such as the airbag spacing,cross-sectional shape,wall thickness,quantity,width,and height of the soft finger)on the motion characteristics and deformation performance of the newly proposed soft finger,based on which,optimization design of the soft finger is completed.When using the 3-D printing technology,we fabricated the mold required for the production of the soft finger.Then,the Dragon Skin 30 silicone rubber was selected to make the finger.(2)Based on the Yeoh energy density model,the principles of virtual work and the torque balance,a systemic mathematical model between the air pressure and bending deformation of the newly proposed finger was built.To established the kinematics model of the soft finger,the piecewise constant curvature theoretical model(PCC)and the DH parametric method were used,which played a theoretical foundation for the grasping control of the soft manipulator.(3)To use the newly proposed soft finger,a three-finger-based soft manipulator was constructed.In the meanwhile,a pneumatic proportional valve produced by Festo company was used as the core to build a pneumatic control system for soft manipulator.Also,a high-performance 32-bit ARM microcontroller was used to develop an electrical control system for the soft manipulator,in which driving air pressure control,air pressure sensor monitoring,data/command wireless transmission,and recording were realized.Moreover,a special monitoring software in a PC terminal was developed by using the Lab VIEW.(4)The finite element analysis(FEA)and experimental testing were combined to investigate the influence of the driving air pressure on the bending deformation and fingertip coordinates of the soft finger,and then to verify the effectiveness of the established bending angle model and kinematics model.To evaluate the proposed the comprehensive performance of the newly proposed dual-cavity-composite-structurebased soft finger,a single-cavity SPN,a single-cavity FPN,a dual-cavity SPN,and a dual-cavity FPN soft fingers have been designed and manufactured,and performance comparison experiments have been carried out.The results show that the new soft finger shows the optimal comprehensive performance,involving the bending deformation,fingertip force,relative stiffness,and fingertip movement range.In the meanwhile,fingertip grasping,envelope grasping,and physical grasping had been tested also.The results show that the newly proposed soft hand embodies a flexible movement ability,strong load ability,and it can realize the non-destructive and stable grasping of items with different shapes and qualities,especially for the fragile items. |
PDF Full Text Request