Design And Implementation Of The Control System For A Pneumatically Actuated Continuum Manipulator

Continuum manipulators have the flexibility that the rigid manipulator cannot match,playing an increasingly important role in many fields;however,there is a significant challenge on its control issue.This paper mainly focuses on carrying out a reasonable structure for the pneumatically actuated continuum manipulator with flexible pneumatic actuators(FPA),designing its hardware system,and constructing experimental platform.Furthermore,for the problem of strong nonlinear control,a model-free control method is developed,which is exactly a data-driven control strategy,to address the shape control issue for a pneumatically actuated continuum manipulator.Aiming at the requirements of the compliant capture task using the pneumatic continuum manipulator,firstly,the biomimetic mechanism of continuum organism is analyzed.Inspired by that,the action mode of the continuum arm,the type and assembly position of the actuators are determined according to the hydrostatic skeletons.Secondly,the internal structure and working principle of the flexible pneumatic actuator are analyzed after the determination of their reasonable layout.Air pipe and electrical wiring are settled,which means the pneumatic continuum manipulator can flexibly achieve the bending/stretching motion afterward.Finally,with designed mechanical structure,the working principle of the pneumatic system and the control system are illustrated.Then,the components of the systems are selected correctly for the purpose of rapidity and stability.The experimental platform is built in the end.Based on the functional frame structure,the single-air-channel simulation model is constructed with modified model of the FPA.The rationality of the system design is verified by numerical simulation,which provides the idea for realizing the control system.Furthermore,for the problem of super-redundancy of the pneumatically actuated continuum manipulator with multi-air-channels,it is necessary to design a reasonable kinematics model to reflect the relationship between joint space and task space.Regarding to the singular problem occurring in homogeneous transfer matrix while under the vertical state,a modal kinematics is established according to the mode shape function for that reason.Aiming at the problem of excessive computation caused by the integral expression of complex terms in the dynamic model of continuum manipulator,the recursive calculation method is used to simplify the dynamic model expression.Because of the uncertainties of the system model and the strong nonlinear problem,the model-free adaptive sliding mode controller(MFASMC)is proposed in order to better shape the pneumatic continuum manipulator.Firstly,the equation of motion is processed as a full-form dynamic linearization based on the generalized Lipschitz condition.Secondly,with a particular criterion function,model-free adaptive control law(MFAC)is proposed,where the pseudo partial derivative matrices are estimated according to the modified projection algorithm.In order to speed up the convergence speed of the error,the sliding mode control law(SMC)is designed to act on the controlled object jointly.In the end,the effect of the control algorithm is observed through numerical simulation,which is compared with PD controller;furthermore,the MFASMC is employed on the experimental platform,performing the smoothly capture task,to verify its effectiveness.