Development Of A 5-DOF Hybrid Robot For Intersecting Curve Flame Cutting

This dissertation presents a theoretical package for kinematics and workspace analysis, continuous path planning, development of the PC based control system for a new 5-DOF hybrid robot known as the TriVariant-B, out of which a pipe intersecting curve cutting machine has been developed. The following contributions have been made.The inverse kinematic analysis of the 5-DOF hybrid robot is carried out using vector based method and the interference and singularity free solution is selected. By using Newton-Raphson method, the numerical algorithm is developed to solve the forward displacement problem of the 2-DOF spherical parallel module. It takes less than 35μs to solve the forward displacement problem using this algorithm and thereby can be used for the real time applications. The Jacobian matrix of the hybrid robot is formulated, which is useful for the tool path planning and motion control.Given the dimensional parameters and the joint limits, a geometrical constraint method is presented to determine the boundary of the reachable workspace. In addition, the project orientation workspace of the end-effector at any arbitrary point within the position workspace is achieved by using polar coordinate systems. As a result, the continuity of the motion of the end-effector within these workspaces can be ensuredA novel path planning method for generating point-vector trajectory is proposed and algorithms of time synchronization and the transitions between different path segments are developed. On the basis of velocity profile analysis, an approach for trajectory planning and interpolation is proposed for generating parametric and implicit space curves. Computer simulations show that the ideal trajectory accuracy up to the second order approximation can be obtained. The real-time trajectory in joint space is also obtained using piecewise cubic splines to achieve C2 continuity. The hardware platform of the TriVariant-B robot control system is developed based on PC and motion controller and the reconfigurable of the software architecture is designed to meet demands in various applications such as cutting, welding, light machining, assembly, pick-and-place, etc. The graphical programming environment LabVIEW is employed to develop the key control functions such as homing, trajectory control, JOG control, online simulation, network data communications, etc. and great efficiency has been achieved in the development and testing procedure due to the special manner of data flow diagram.The TriVariant-B robot has been used to develop a pipe intersecting curve frame cutting unit and the techniques to improve its accuracy, efficiency and applicability are investigated, such as fast home position calibration, quick localization of the steel pipe in the world coordinate systems, trajectory planning of intersecting curve cutting with bevel angles, etc. As a result, the products have been widely used in the construction of flare stack tower pylons in petrochemical enterprises.