High precision trajectory planning on freeform surfaces for robotic manipulators

Abstract

The traditional programming method for industrial robots is teaching by demonstration with a joystick or teaching pendant. However, high precision welding, machining, painting or thermal spraying, and other tasks require pre-computed trajectories, since an operator would not be able to accurately guide the manipulator and achieve suitable results. Giving the CAD model of a 3-D freeform surface, and the operating parameters of the task, this paper describes the methodology and steps involved in off-line programming for automatic trajectory generation. The computed waypoints comprise position, orientation, manipulator's end-effector velocities, and accelerations. This work describes the software platform employed for simulation, surface sampling, the use of radial basis function (RBF) for surface modelling, and intersection of surfaces (marching method) to generate paths. The case study for the developed method is the EMMA project <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∗</sup> , a robotic system for in situ high velocity oxy-fuel coating (HVOF) of hydraulic turbine blades. The results highlight the efficacy of the method and the impact of the solution for similar problems.