Passive-joint sensors for parallel robots

Beside a quantity of well-known positive characteristics parallel robots also obtain a couple of negative properties limiting their efficient use in certain application areas nowadays. Additional sensors integrated in the passive joints provide the possibility to overcome several of these limitations simultaneously thus leading towards an increasing overall system performance. In detail, different control functions, necessary for fast, precise and safe robot operation like calibration, workspace monitoring and position control can be improved. To tap the potential of the concept of passive joint sensors, algorithms to evaluate the additional sensor information for certain control functions and an approach to determine the necessary sensor resolution for a class of parallel robots are developed. Different sensor configurations are investigated and compared due to computational efficiency and resolution demands. Furthermore, specifications of passive joint sensors for parallel robots in industrial environments are discussed. Based on these requirements, we report on the development of new inductive microsensors for angle measurement capable for integration e.g. into rotary joints of high-performance parallel robots. Basic design and process technologies of the single sensor components as well as first measuring results are described.