| Tunnel shotcreting manipulator is widely used in all kinds of highway and railway tunnels and mines.Aiming at the problems of low degree of automation,complex manual operation and potential life and health hazards in the use of all kinds of shotcreting manipulator on the market,the research on Tunnel shotcreting manipulator is carried out.In this paper,firstly,the kinematics of the mechanism is analyzed.Secondly,combined with the shotcreting technology and construction technical specifications,the shotcreting deposition rate model and tunnel shotcreting trajectory generation algorithm are studied.Aiming at the motion characteristics and kinematics programs of an 8-DOF manipulator,the forward kinematics model of the mechanism is established based on D-H method,and the velocity Jacobian matrix is established based on vector product method.In order to analyze the inverse kinematics of the mechanism,a twice-calculated method is proposed to solve its inverse kinematics.First,a set of optimized numerical inverse solutions is obtained based on the weighted minimum parametric method of the joint avoidance limit optimization function,based on which the analytical solution of the inverse solution is derived by the joint angle parameterization method,and finally the inverse kinematics and joint avoidance limit are simulated and verified by the linear motion trajectory.For the prediction of concrete coatings deposition thickness in the spraying process,the influencing factors of the spraying process are analyzed and relevant reasonable assumptions are made,a beta distribution model is proposed to describe the shape of the coating thickness distribution and a planar spraying deposition rate model is established,a dynamic spraying model is established for the linear and circular trajectories commonly used in actual spraying and an example is given for simulation verification,considering the actual surface to be sprayed.Based on the plane shotcrete deposition rate model,the shotcrete deposition rate model for complex free-form surfaces is established,and the overlap spacing of adjacent trajectories is modeled for the multi-trajectory shotcrete spraying problem and solved optimally with the objective of regional flatness for adjacent trajectories.Aiming at the problem of tunnel automatic shotcreting operation,combined with the shotcreting technology and construction technical specifications,the tunnel automatic shotcreting strategy is proposed.Based on this strategy,the point cloud model of the tunnel surface to be shotcreted is divided into sections,layers and slices.The shotcreting trajectory generation algorithm within the slice area is mainly studied.The bounding box slice method is used to slice the point cloud model,and the point cloud projection method is used to get the result.In order to realize the interpolation and fitting of the original trajectory points in the slice,the interpolation algorithms of spatial straight line trajectory,circular arc trajectory and B-spline trajectory are studied,and a simulation example is given to verify the results.Finally,the specific structure of the prototype is designed,the important joints and key components are simulated for driving force and stress,and a control system with Trio controller as the core is built and the motion control experiments are conducted to verify the automatic shotcrete spraying capability. |
