Design And Experimental Study Of Multi-degree-of-freedom Flexible Manipulator With Variable Stiffness

Aiming at the limitation of flexible robot technology in variable stiffness characteristics,based on the principle of biomimetic muscles and the braided pneumatic artificial muscle as a new intelligent material,a multi-degree-of-freedom variable stiffness soft manipulator is designed around the variable stiffness characteristics of the soft robot.The research is carried out systematically from the aspects of configuration design,theoretical modeling,prototype making and experimental testing,which broadens and enriches the research methods of flexible robots in the field of variable stiffness,and it provides a new design idea for exploring the variable stiffness characteristics of flexible robots.Firstly,based on the principle of biomimetic muscles,the structural characteristics of Octopus hand muscles are analyzed,and the design mechanism of crisscross muscles is summarized.According to the biomimetic entanglement principle,the transverse muscles are designed as spiral-wound type.Combined with the structural characteristics and performance advantages of the new pneumatic artificial muscle actuator,the configuration scheme of the multi-degree of freedom variable stiffness soft manipulator model is put forward.The scheme model is designed by the three-dimensional mapping software concretely,and carried out the planning and analysis of its regular motion modes.Secondly,starting from the structural characteristics of the model,the shrinkage and expansion characteristics and mechanical properties of the pneumatic muscle actuator are studied and analyzed.Based on the structural characteristics of the soft robot and the assumption of equal arc,the kinematics and statics analysis of the whole model are carried out by using the improved D-H method.The homogeneous transformation equation and static equilibrium equation of the end posture are solved,and the workspace of the end of the manipulator is drawn.Then,according to the configuration scheme of the soft manipulator,starting from the practical engineering concept,spring is added to the transverse artificial muscle as the skeleton to maintain its spiral shape,and the prototype of the manipulator is developed by cooperating with the longitudinal artificial muscle.According to the driving characteristics of artificial muscle,a set of hardware control system with good stability,real-time and high integration is built.Finally,the upper computer control system based on MFC module is compiled,and an experimental platform for the software manipulator is established.The mechanical properties of a single artificial muscle are tested,and the variable stiffness characteristics of the whole muscle are verified.Then the theoretical values of kinematics and statics are compared and analyzed with the experimental data,and various kinds of grasping experiments are carried out.