Study On The Control Of Wind Turbine Blade Grinding Robot

As clean reproducible energy, wind energy has winned more and more good graces. As one of the important parts of wind turbine, blade is always damaged by the sand disaster and the erosion of salt spray, besides, the adsorption of insects and dirt in the air always destroy the surface finish, and the operation cost and safety are affected. The common method of recover the surface finish is grinding and reprocessing. The blade is so huge that its maintenance cost is very high, much short fiber and harmful dust is produced during the grinding process. With the outbreak increase of wind energy installed capacity recent years, quite a few blades has entered maintenance period. As more and more blades require the maintenance, how to provide the timely and effective grinding maintenance has been a key technique. The application of robot in blade repairing has many advantages, such as high quality and low cost, reduce the harm of dust and the work intensity, so it is an effective method of liberating worker from the high pollution and intense work.As we know that the blade is always very huge, so mobile manipulator should be adopted as the grinding robot. The mobile manipulator composed of mobile platform and manipulator, is a complex robotic system with the function of movement and operation. It has the advantages of operation flexibility and space broadness. A mobile grinding robot is presented here, with a grinding tool fixed on the end of mobile manipulator. The complex structure and non-holonomic constrain of the mobile manipulator, and the existing dynamic coupling between the platform and manipulator, all these factors bring a great challenge to the control of the robotic system. Besides, there exists interactive force between the manipulator and external environment during the working process, so the effective control of operation force is one of the core problems.A mobile manipulator equipped with grinding tool is used for wind turbine blade maintain mobile robot, as recoording to the characteristic and requirement of blade grinding. The following research work has been carried out.The structure scheme of the mobile wind turbine blade grinding robot is analyzed and determined. The hierarchical control structure of grinding robot is built. And the control strategy of free movement and end-point contact manipulation is determined. Kinematics modeling of mobile platform, manipulator and grinding robot has been finished. The controllability of the robot system has been analyzed, and the motion constraint equation has been derived. The workspace has been gained by building the mechanism model of the manipulator with SimMechanics. The dimension data of typical section has been analyzed to learn the size range of the blade, the rationality of robot mechanism has been verified by comparative analysis.The kinetic equation of the grinding robot is built by Lagrange energy balance method, and the kinetic equations of platform and manipulator are derived from the robot’s, based on which the dynamic coupling is derived. The rule of how the dynamic coupling affects the subsystems is derived by the simulation based on the built SimMechanics model. The finished work affords the base for control system research.The control strategy has been studied. A backstepping velocity controller has been built for the mobile platform, and a dynamic controller with stable convergence is built with considering the velocity controller. A proportion differential plus feedforward compensation controller is built for the manipulator. Compensation is considered for the dynamic coupling between the platform and manipulator, so as to improve the control effect.Force/position hybrid control and impedance control have been compared, and impedance control is accepted as the operation force control strategy. An impedance controller has been built, and simulation is carried out, the finished work establishs foundation for the operation force control of blade grinding process.Coordinate system of blade grinding system is built. Pose and joint velocity description relativing to base coordinate have been derived. The influencing factors of grinding force have been analysised. The control model of the the blade grinding process has been built. The simulation platform based on Solidworks, ADAMS and Matlab/Simulink has been established, and the simulation experiment has been carried out, the feasibility of the grinding robot and its control system has been verified by the experimental results.