Design of asynchronously stimulated robot behaviours

The paper presents how the design of robot control systems should deal with two fundamental aspects of their functioning: asynchronous arrival of data from the environment and their processing resulting in the required system behaviour. The behaviour of the system is described by transition functions. However, the definition of those functions must take into account that not all data required for controlling the system are readily available, thus different variants of transition functions taking into account only the currently available data have to be defined. The overall system behaviour is then specified in terms of Petri nets, while the mathematical expression of the transition functions is complemented by the use of data flow diagrams. The paper presents the general design method and exemplifies it on the case of a robot visual servo utilising two cameras: an eye-in-hand and a stand-alone one.