Research On Key Technology And Application Of McKibben Muscle For Soft Robot

As opposed to traditional rigid robots,soft robots are usually made of low cost,flexible and lightweight materials,which is more suitable to cope with unstructured environments.Robots with soft and compliant bodies are particularly apt to these applications due to their flexibility,versatility and claims to safety.McKibben muscle is a new type of flexible actuator possessing the characteristic of light weight,large output force,flexible,environment-friendly,safety and easy to install,and is an ideal actuator and component material for soft robot,which has already attracted many researchers and national governments.The main contents of this dissertation are briefly addressed as following:(1)First,according to the working principle of McKibben muscles,self-made and expansive McKibben muscles are fabricated and tested,and the stiffness identification models are established.Then a novel variable stiffness soft robotic arm composed of both three contractile and one extensor McKibben muscles is designed,whose stiffness can be adjusted independently of its length.Based on assumptions of output forces of McKibben perpendicular to end-effector,the decoupling of stiffness and location is realized.Based on assumptions of curve movement of this soft arm,the kinematics model is established;the model of relationship between stiffness and inflation pressure of McKibben muscle is established.A stiffness test platform is designed,and the static stiffness model is verified through experiments,so the static model lays a theoretical foundation for position and stiffness control of the soft arm.(2)In order to develop McKibben bending actuators,a novel actuator,SMA-fishing-line is designed and fabricated.A voltage driving model of the SMA-fishing-line is established;contrast experiments of isometric and percentage contraction are carried out.An antagonistic bionic joint driven by the novel SMA-fishing-line actuators is presented,and based on an extended unparallel Prandtl-Ishlinskii(EUPI),its hysteresis model is established.Based on this accurate hysteresis model,a composite PID controller consisting of PID and an integral inverse(I-I)compensator is proposed and its performance is compared with a traditional PID controller through experiments.Finally,a bending actuator,SMA-fishing-line-McKibben muscle is designed and fabricated.The performance tests are carried out.A control method for output force is proposed,and the effectiveness of control system is verified through output force experiments.A gripper driven by SMA-fishing-line-McKibben muscles is designed,and the feasibility of the gripper is verified.(3)PAM possesses strong nonlinear,which is not convenience for control.Auto/Active Disturbances Rejection Controller(ADRC)is designed to control the position and stiffness of McKibben muscle.Because the parameters of ADRC are difficult to adjust,fuzzy adaptive theory is merged with ADRC,and FADRC is designed.Parameters of NLSEF(nonlinear state error feedback control law)and ESO(extended state observer)can be adjusted through fuzzy methods on-line,which increase the robustness of ADRC.Using MATLAB/Simulink,the effectiveness and practicality of control system are verified through simulation.Aimed at the stiffness model and the kinematics model of soft arm designed in chapter two,test rig and control system of stiffness and position control are set up based on Arduino,and the effectiveness of the FADRC controller are validated through variable stiffness control and position control tests.Then variable stiffness soft arm and gripper of SMA-fishing-line-McKibben muscles are assembled,the experimental verification of grasping and passing item task for the soft arm is completed.(4)Aimed at the characteristic of driving medium(pneumatic and hydraulic)of McKibben muscle,a method which allows McKibben muscles filled with water to operate in both compliant pneumatic and stiffer hydraulic modes is proposed.An arm with one degree offreedom driven by pneumatic and hydraulic McKibben muscle is set up,and the contrast tests of these two driving modes are conducted.A method of simultaneously controlling both the hydraulic and pneumatic valves has been demonstrated,and position tracking control is realized.