On the Validation of Robotics Control Systems Part II: Analysis of real-time closed-loop control tasks

In the framework of the {\sc Orccad} system, periodic and multi-rate control laws are implemented in terms of a set of computing tasks to be executed under a real-time operating system. Simulations and experiments demonstrate that partially synchronizing such tasks can improve the practical performance of the implementation. In this paper, we examine the consequences of introducing such synchronisation in terms of two temporal problems which may occur and how they may be detected using Petri net modeling. We conclude with some guidelines about how to add such synchronisation to design deadlock free and efficient real-time periodic control laws