Research On Automatic Cross Section Profiling Theory And Control Strategy For Boom-type Roadheader

Boom-type roadheader has found widespread application in tunnel excavation. In recent years, research on automation and automatic cross section profiling of boom-type roadheader has become a focus abroad, and some of the results have been put into practical application. However, these studies are still in its infancy in our country. The final aim of researching on automatic roadheader is to replace the manually operated roadheader, develop its application domain, adapt to poor working conditions, cut production cost, improve tunnel profiling precision, reduce labor intensity and increase production efficiency. The goal of this thesis is to achieve automatic cross section profiling of longitudinal axis boom-type roadheader. Kinematics, dynamics and electro-hydraulic proportional control system for the roadheader are analyzed and modelled. Monitoring theory of cross section contour, as well as cutting trajectory planning theory and control strategy are studied. The overall coordinate system of roadheader is constructed, and close kinematics loop is established. Kinematics of manipulator, body and roadheader are analyzed using the theory of homogeneous transformation and robotic kinematics, and the kinematics equations in the joint space and the drive space are established, and spatial position of roadheader cutting head are given. Kinematics simulations are completed.Cutting resistance forces are analyzed and studied. Based on the D'Alembert principle and the Lagrange equation, the joint generalized force, the joint generalized torque and the dynamic model of the roadheader manipulator are established. Research showed that the dynamatics equation is closely related to the form and the position of the manipulator, and have the characteristics of non-linear and strong-coupling.The pressure compensation electro-hydraulic proportional system of the roadheader is designed, and the working principle of LSS (Load Sensing System) is analyzed. Models of the hydraulic control system for the roadheader manipulator are deduced. Some key parameters are estimated and identified. Study showed that the hydraulic control system model is multi-variable, slow time-varying and non-linear.Real-time monitor of the position of the cutting head and the size of the contour is very important to automatic cross section profiling. From structure of the cutting head, coordinates of pick are established according to position of contour boundary. Relations among the cutting limit scope of the pick, the joint angle of the manipulator, and the cutting depth are analyzed, and coordinates of the contour boundary are given. Curve equation and coordinate of the cross section contour and the directional expression of tunnel centerline are established.Shapes of the cutting trajectory are analyzed and summarized, and trajectory plannings of the manipulator in the joint space and the driving space are developed by straight-line interpolation method with parabola transition, and simulations are carried out. Calibrations of the non-parallel cross section and adjustments of the cross section are studied.With the joint angle, the cylinder drive force, the cylinder output speed and travel as controlled objects, control strategies of accurate trajectory tracking for the manipulator are studied, which include non-linear PID control of the joint angle, variable structure control of the cylinder drive force and model reference adaptive control of the cylinder output travel. Control algorithms are designed, and simulations and experiments are carried out. It is shown whatever for control precision and velocity the accurate trajectory tracking is reached using the adaptive control of the cylinder drive velocity and travel. So the adaptive control in the thesis can be utilized for trajectory tracking control of the manipulator. The results of experiment proved the validity of the fundamental research.