Research On Modeling And Control Of Gliding Motion Of Underwater Gliding Snake Robot

The underwater gliding snake robot is a new kind of underwater bionic robot.It introduces gliding gait on the basis of underwater snake-like robot,so that it can achieve long distance gliding movement through buoyancy regulation system on the basis of retaining underwater snake-like robot.However,as a new type of bionic underwater robot,there is a gap in the robot model,and the design of the relevant motion controller is rarely proposed.For this purpose,the kinematics analysis and dynamic model of the water-sliding snake-shaped robot were firstly carried out,and the hydrodynamic parameters with great influence were simulated.Based on the established model,a tilt motion controller based on backstepping method is designed and processed for external disturbance.Firstly,the motion principle and joint structure of underwater gliding snake robot are designed and analyzed.Secondly,the subsequent modeling of the robot is hypothesized and explained.After that,the relative coordinate system is established with the body as the coordinate center,and the definition of relative motion parameters and kinematics is introduced.According to the momentum theorem and moment of momentum theorem,the 3d gliding motion equation of the robot is deduced.In order to obtain the drag force,lift force and pitch moment of underwater gliding snake robot when it is in gliding state,the hydrodynamic parameters of the second generation new underwater gliding snake robot were solved by using CFX software using computational fluid dynamics method.:According to the routine working form of underwater gliding snake robot,the vertical plane working form of underwater gliding snake robot is analyzed.Based on the obtained nonlinear motion model,the optimal quadratic control strategy LQR is adopted to design the state feedback controller to verify the validity of the motion model.Considering that the linearization may cause the performance of the controller to decrease,a new trim motion controller based on the anti-step method is designed,and the stability of the controller is proved.The control effects of the two are compared in the simulation experiment,and the superiority of the inverse step controller is proved.Aiming at the problem that the underwater gliding snake-like robot(UGSR)has input constraints and unknown external disturbance when implementing gliding motion,the backstepping control method based on Nussbaum function and nonlinear disturbance observer is proposed to improve its pitching motion tracking performance.The vertical plane motion of the under-actuated underwater gliding snake-like robot is analyzed and conditionally simplified,and the corresponding kinematics and dynamic equations are obtained.Nussbaum function and hyperbolic tangent function are combined to deal with the problem of system control input saturations,which avoids the controller singularity problem of the latter,and the nonlinear disturbance observer is used to effectively observe and compensate the external complex disturbance.The backstepping controller for designing pitching motion tracking,in which the computational expansion problem caused by the virtual item in the backstepping method is eliminated by the dynamic surface method.The controller designed based on Lyapunov stability theory ensures that the system can achieve global uniform stability of velocity and position semaphore.The results show that compared with the traditional backstepping method,the proposed scheme can improve the response time and error convergence speed to some extent,and the nonlinear disturbance observer has a good performance for the observation of complex disturbances.The designed controller can effectively track the longitudinal motion of the robot under the unknown disturbance and has strong robustness.On the basis of theoretical research,the principle prototype platform of underwater gliding snake robot is introduced,including its structure design and control system.On this basis,relevant experimental studies were carried out to verify the snake movement and glide movement of underwater gliding snake-like robot,and verify the correctness of relevant theoretical analysis as well as the maneuverability and efficiency of the experimental platform.