Development of a Method and Strategy for On-Line Reconfiguration of Cable- Driven Parallel Robots as Handling Devices

Due to their parallel and modular structure, cable-driven parallel robots are very well suited for the implementation of a reconfiguration option. The term reconfiguration refers to the adaptation of the robot structure to a changed requirement. Practical measures are, for example, the addition and removal of cables or the displacement of pulleys. Thus, the implementation of a reconfiguration feature on a cable robot increases the range of realizable properties enormously. In the first funding period, a general data model of a reconfigurable cable robot was developed, which allows the depiction of discrete and continuous reconfiguration options. Based on the data model, a strategy to plan a reconfiguration procedure according to a given workspace requirement was introduced. In addition, a procedure for the structural and geometric reconfiguration of a “Computerized-Numeric-Control” system (CNC) was developed and validated by means of a simulation with a real control system.The aim of the follow-up project is to further refine the used workspace description, as well as the process of reconfiguration planning and finally to bring the results together. Currently, the planning of the reconfiguration is based on a method for workspace calculation, that uses an algorithm for cable force distribution. In order to eliminate the dependency on a cable force distribution algorithm, a method for the efficient evaluation of the workspace boundary of the controllable workspace, which is a pure geometric concept, is to be developed. With regard to the planning process based on optimization, the entire process is to be formalized further. With a uniform description of the entire procedure, different methods can be compared directly. For example, it becomes possible to assess the efficiency and accuracy of different numerical solution schemes. Finally, the results of the planning strategy and the practical reconfiguration are to be brought together by a discrete state modelling, followed by the implementation in the real robot afterwards.The steps required for the further implementation of a reconfigurable cable robot are divided into four independent work packages. Within the first package, a method for the efficient calculation of the controllable workspace is to be developed. Based on this, the process of reconfiguration will be further formalized, in order to investigate different numerical solution schemes as well as quality functions. In the last work package a state modelling of the different modules of a reconfigurable cable robot shall be designed and implemented on the existing target system.