Design and analysis of synchronization for real-time closed-loop control in robotics

In the framework of the ORCCAD system, periodic and multirate 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. However, using synchronizations may lead to dead-locks or temporal inconsistencies. In this paper, we examine the consequences of introducing such synchronization in terms of structural and temporal problems which may occur and how they may be detected using Petri net modeling and analysis. We conclude with some guidelines about how to add such synchronization to design deadlock-free and efficient implementations of real-time periodic control laws.