Abstract: In a robot motion control system a modular sensor data preprocessing unit is provided between the sensors and a motion control unit. Modules in the data preprocessing unit are activated in a temporal sequence in accordance with the kinds of sensors involved and the technological task to be performed. The data preprocessing unit comprises a data transfer control circuit, a basic function control circuit and a complex function control circuit, each such circuit including a plurality of independently activatable function modules. For example, the complex function circuit includes a velocity control module and a path correction module.