A novel second order filter for the real-time trajectory scaling

Online trajectory scaling approaches represent a possible way for handling robotic systems characterized by kinematic or dynamic saturations. Scaling methods are based on the path/velocity decomposition principle: a dynamic filter is used to modify the longitudinal velocity along a planned path in order to satisfy given system constraints. The strategy here proposed enhances the results of a previous work by enlarging the number of considered constraints. In particular, still accounting for the existence of bounds on joint velocities and torques, in this paper, the presence of constraints on joint accelerations is also considered. Furthermore, the nonlinear filter, which represents the core of the scaling system, has been revised in order to devise a new and more compact implementation. Finally, some practical issues that could occur in actual implementations are discussed and solutions are proposed to overcome possible problems.