Small industrial robots for on-aircraft repair of composite structures

In this paper, a new approach for an "on-aircraft" milling system for composite scarfing is proposed. Different types of kinematics are compared by defined criteria. Small industrial robots show a high potential to be a competitive solution for this application. The main disadvantage of industrial robots is the low rigidity, but for on-aircraft application there are additional elasticities expected anyway due to the fixation device and the workpiece. Hence, the three general possibilities for reducing the tool path deviations in an elastic system are discussed and corresponding methods are presented and partly investigated. Thereby, an investigation of the elasticity of some commercial small-size industrial robots is presented. In addition, it is shown that the accuracy of small robots can be increased by compensation of the robots' elasticities. Finally, a feasible approach for an online compensation method is presented.