This paper describes a modeling methodology to support the design process of complex systems. The main challenge in modern industrial applications is the sheer volume of data involved in the design process. While using high-level abstraction is necessary to manage this data and analyze the system “as a whole,” designers need also to retain all the low-level information of the system, in order to be able to perform optimizations and modifications at later times. The solution proposed here is to use a hierarchy of models, each one describing the system at different levels of abstraction, and arrange them in such a way that it is possible to easily “map” each level onto the others. The topmost layer of the system description is expressed in System Modeling Language, a general-purpose modeling language based on Unified Modeling Language.

ISO/TS 15066 is globally recognized as the guideline for designing safe collaborative robotic cells, where human and robot collaborate in order to fulfill a common job. Current approaches for implementing the ISO/TS 15066 guidelines lead to a conservative behavior (e.g. low velocity) of the robot and, consequently, to poor performance of the collaborative cell. In this paper, we propose an approach based on control barrier functions that allows to maximize the performance of a robot acting in a collaborative cell while satisfying the ISO/TS 15066 regulations. The proposed approach has been successfully validated both in simulation and through experiments.

The paper describes a control architecture for industrial robotic applications allowing human/robot interactions, using an admittance control scheme and direct sensing of the human inputs. The aim of the proposed scheme is to support the operator of an industrial robot, equipped with a force/torque (F/T) sensor on the end-effector, during human/robot collaboration tasks involving heavy payloads carried by the robot. In these practical applications, the dynamics of the load may significatively affect the measurements of the F/T sensor. Model-based compensation of such dynamic effects requires to compute linear acceleration and angular acceleration/velocity of the load, that in this paper are estimated by means of a quaternion-based Kalman filter and assuming that the only available measurements come from the forward kinematics of the robot. Experimental results demonstrate the feasibility of the approach and its industrial applicability.

This paper describes a modeling language that aims to provide a unified framework for representing control systems, namely, physical plants coupled with computer-based control devices. The proposed modeling methodology is based on the cardinal principle of object orientation, which allows describing both control software and physical components using the same basic concepts, particularly those of capsules, ports, and protocols. Furthermore, it is illustrated how the well-known object-oriented specification language unified modeling language can be adopted, provided an adequate formalization of its semantics, to describe structural and behavioral aspects of control systems, related to both logical and physical parts. Note to Practitioners-The development of an automated system within an industrial setting is a complex task, whose successful result depends on the joint efforts of a team of designers with different scientific backgrounds and specialized knowledge. In fact, an automated system is typically composed of a mechanical assembly, which must be precisely designed and manufactured, and a set of sensors and actuators (e.g., electrical drives, pneumatic systems, etc.), which are, on their turn, controlled most of the time by means of digital processors. Of course, both electrical parts and control algorithms (e.g., proportional, integral, and derivative (PID) regulators, logic and supervisory control, reference trajectories for mechanical motions, etc.) should be designed with the same care given to mechanical aspects. Moreover, it is undeniable that none of the various parts composing the automated system design specification can, on their own, allow engineers to understand the actual behavior of the whole system, especially without a common description language that is understandable for all of the designers. The present paper introduces a unified language which aims to support integrated design specifications of automated systems, including the dynamics of heterogeneous physical assemblies, the discrete-event behavior of distributed control software, and the specification of interface ports between the plant and the control system. With the proposed language, it is possible to obtain a complete picture of the automated system suitable for its simulation, documentation, and validation. The modeling language described in the paper supports the principles of object orientation. This choice moves in the direction of enhancing modularity and reusability properties of design specifications, which are aspects of great importance in the design practice. Moreover, the object-oriented approach to automated systems design proposed in the paper aims to introduce the concept of "design by extension" in the manufacturing industry. This means that the definition of specialization relationships between classes of components implies that those components should be designed in order to be substitutable with each other, especially from a dynamic point of view. This aspect will be the subject of further papers illustrating other practical insights on the use of object-oriented models for automated systems