Modeling and Validation of a Web Ontology Language Based Disassembly Planning Information Model

Disassembly, a process of separating the end of life (EOL) product into discrete components for re-utilizing their associated residual values, is an important enabler for the sustainable manufacturing. This work focuses on the modeling of the disassembly planning related information and develops a disassembly information model (DIM) based on an extensive investigation of various informational aspects in the domain of disassembly planning. The developed DIM, which represents an appropriate systematization and classification of the products, processes, uncertainties, and degradations related information, follows a layered modeling methodology in which DIM is subdivided into layers with the intent to separate general knowledge into different levels of abstractions and reach a balance between information reusability and information usability. Two prototype disassembly planning related applications have been incorporated to validate the usability and reusability of the developed DIM.

Optimal Control of a Hybrid Rhythmic-Discrete Task: The Bouncing Ball Revisited

Rhythmically bouncing a ball with a racket is a hybrid task that combines continuous rhythmic actuation of the racket with the control of discrete impact events between racket and ball. This study presents experimental data and a two-layered modeling framework that explicitly addresses the hybrid nature of control: a first discrete layer calculates the state to reach at impact and the second continuous layer smoothly drives the racket to this desired state, based on optimality principles. The testbed for this hybrid model is task performance at a range of increasingly slower tempos. When slowing the rhythm of the bouncing actions, the continuous cycles become separated into a sequence of discrete movements interspersed by dwell times and directed to achieve the desired impact. Analyses of human performance show increasing variability of performance measures with slower tempi, associated with a change in racket trajectories from approximately sinusoidal to less symmetrical velocity profiles. Matching results of model simulations give support to a hybrid control model based on optimality, and therefore suggest that optimality principles are applicable to the sensorimotor control of complex movements such as ball bouncing.