Ensuring safe and effective physical human-robot interaction (pHRI) remains a critical challenge in industrial robotics, particularly in ensuring compliance with ISO/TS 15066 safety standards. This paper proposes a novel framework to achieve a safe and robust physical human-robot interaction (pHRI). The framework adapts the parameters of a variable admittance controller online in order to guarantee passivity and compliance with ISO/TS 15066. Passivity is guaranteed using an energy tank, while a safety constraint explicitly handles the Power and Force Limiting (PFL) energy limit. Experimental validation on an industrial robot demonstrates the effectiveness of the framework.

In recent years, production systems have become highly sophisticated and complex. As a result, while on the one hand, the least-skilled labor has been partially displaced by machines, high-skilled labor is more required to supervise and control advanced automation systems. In many cases, the complexity of machines implies an increased complexity of human–machine interfaces (HMIs), which are the main point of contact between the operator and the machine. To enable effective use of HMIs and to enable their usage by workers with different knowledge and capabilities, novel design approaches have been proposed. In particular, in this article, we consider the approach developed in the framework of the European research project INCLUSIVE, which aimed at designing industrial HMIs that adapt to the skills and capabilities of human operators. As a case study, we consider an adaptive interaction system for the woodworking industry and present an extensive evaluation carried out in real production environment with shopfloor workers. The effectiveness of the INCLUSIVE approach has been assessed with subjective and objective measurements and compared to that of interaction systems customarily used in industry. Results have shown that users appreciated the INCLUSIVE system and largely preferred it over the customary system. Moreover, with regard to objective performance-related measurements, they performed better when using the INCLUSIVE system since they received tailored guidance during the considered working tasks. Note to Practitioners— This article was motivated by the fact that advanced automation systems are often highly complex for human operators. To address this problem, we focus on the importance of designing the automation system around users and discuss an approach for adaptive automation, called INCLUSIVE. Its main feature is that it adapts the human–machine interface (HMI) according to operator’s skills, capabilities, and current mental fatigue. In this article, we provide an extensive evaluation of the INCLUSIVE system, considering a company producing woodworking machines as a use case. Assessment was carried out in the company shopfloor, considering real workers, and the INCLUSIVE system was compared with the customary HMI running on the company machines. The results of our study suggest that adapting the interaction to operator’s needs allows better working performance while letting workers more satisfied with the use of the system.

This paper deals with the traffic management of multiple Automated Guided Vehicles (AGVs) in an automatic factory or warehouse. We propose innovative methods, evolved from the studies previously conducted in [1], to coordinate a fleet of AGVs in an industrial environment, and we describe the methodologies developed to build a complete traffic manager software. The software is based on a multi-layer control architecture: a higher-level layer useful to model the traffic of vehicles among the different areas of the warehouse, a middle layer which acts as a bridge between the traffic model and the path planner, and a lower-level layer which represents the roadmap itself and, hence, defines the optimal path to be followed by each vehicle. Finally, the AGVs movement coordination is managed separately through a centralized control in order to avoid conflicts and deadlocks.The aim is to make theoretical methods applicable to a real environment facing the usual problems related to the industrial applications, which have been overlooked in [1]. Indeed, the roadmap is usually constrained by the plant layout, especially in medium size factories, and paths can not be arbitrarily defined. Hence, the aim is to realize a reliable and robust software able to manage real scenarios, allowing the traffic management of multiple AGVs. The proposed method aims at flexibility by considering a coordination strategy not based on assumptions and ad-hoc rules.

While modern production systems are becoming increasingly technologically advanced, the presence of human operators remains fundamental in industrial workplaces. To complement and enhance the capabilities of human workers, approaches based on adaptive automation have been introduced. They consist of adapting the behavior of the system according to the user’s capabilities and effort. In this article, we present a general holistic framework for adaptive automation, called INCLUSIVE, that assists the operator during working tasks. The system consists of three modules. First, a thorough characterization of the operator’s constitutional and situational condition is provided; based on this, properly tailored adaptation is given, and if necessary, further training and support are provided. The framework has been implemented and tested considering three industrial use cases, selected as representative of a wide area of interest for the industry in Europe, in terms of both production requirements and involved operators. Tests have been carried out in real production environments, considering real production tasks carried out by 53 shop-floor workers. Results have shown that workers’ satisfaction when using the INCLUSIVE system and their performances was increased with respect to customary interaction systems currently used in industries. Moreover, the achieved results were used to formulate a set of recommendations for the design and implementation of an adaptive interaction system in relation to ensuring worker satisfaction and system usability in an industrial environment, as well as performance requirements.Note to Practitioners—This article was motivated by the fact that, despite modern advanced automation, human operators are still central in the manufacturing process. However, technological progress often causes challenging interaction with complex industrial systems. The goal of this article is to introduce a complete framework for adaptive automation, with the ultimate goal of facilitating the interaction of human operators with complex industrial systems. The framework relies on three modules: measurement of human capabilities, the adaption of the interaction system, and additional teaching and support. The three modules are discussed at a high level, independently of the target application. Moreover, to facilitate their application in specific working contexts, examples are provided with respect to three different industrial applications. Results of tests carried out with shop-floor operators show that implementing the proposed framework allows better working performance and increases worker satisfaction with the use of automation.

Modern production systems are becoming more and more complex to comply with diversified market needs, flexible production, and competitiveness. Despite technological progress, the presence of human operators is still fundamental in production plants, since they have the important role of supervising and monitoring processes, by interacting with such complex machines. The complexity of machines implies an increased complexity of human-machine interfaces (HMIs), which are the main point of contact between the operator and the machine. Thus, HMIs cannot be considered anymore an accessory to the machine and their improvement has become an important part of the design of the whole machines, to enable a nonstressful interaction and make them easy to also use less skilled operators. In this article, we present a general framework for the design of HMIs that adapt to the skills and capabilities of the operator, with the ultimate aim of enabling a smooth and efficient interaction and improving user's situation awareness. Adaptation is achieved by considering three different levels: perception (i.e., how information is presented), cognition (i.e., what information is presented), and interaction (i.e., how interaction is enabled). For each level, general guidelines for adaptation are provided, thus defining a meta-HMI independent of the application. Finally, some examples of how the proposed adaptation patterns can be applied to the case of procedural and extraordinary maintenance tasks are presented.

Smart manufacturing is targeted as the next generation of manufacturing by many national and international strategic development. The increasingly rich production data, the integration and extensive application of information technology, and the intelligent data processing and system modeling methods have collectively enabled smart manufacturing. Building upon them, manufacturing system modeling, knowledge acquisition, design, and real-time control are the key components [item 1) in the Appendix], [item 2) in the Appendix]. It is still one of the really huge challenges to gather data, transform them into information, and derive knowledge out of this information, especially given the requirement of knowledge that can be trusted as manufacturing systems may harm humans and the environment if they come to the wrong conclusion. Despite the learning and derivation of knowledge, it could be modeled beforehand and taken, for example, as an environmental model for online decisions like in deliberative agent-based systems. Nevertheless, for decisions during operation, real-time requirements, dependability, and security issues are to be guaranteed. Finally, for acceptance and trust, humans need to “understand” the reasons behind automated decisions; therefore, explainability or at least a white box description is an issue of such knowledge-based systems.

Multi-robot systems are able to achieve common objectives exchanging information among each other. This is possible exploiting a communication structure, usually modeled as a graph, whose topological properties (such as connectivity) are very relevant in the overall performance of the multirobot system. When considering mobile robots, such properties can change over time: robots are then controlled to preserve them, thus guaranteeing the possibility, for the overall system, to achieve its goals. This, however, implies limitations on the possible motion patterns of the robots, thus reducing the flexibility of the overall multi-robot system. In this paper we introduce teleoperation as a means to reduce these limitations, allowing temporary violations of topological properties, with the aim of increasing the flexibility of the multi-robot system.

Collaborative robots are one of the key drivers in Industry 4.0 and they have evolved considerably since the last decades of the 20th century. With respect to the industrial robots, collaborative robots are more productive, flexible, versatile and safer. In the recent years, many industrial robot producers and startups entered the segment of collaborative robots. In this paper, we propose a methodology for developing a comparative analysis of the collaborative robots currently available in the market. The goal of the paper is to provide a framework for allowing the benchmarking, based on common robot parameters and standardized experiments that can be performed with the robot under investigation. An experimental technological review of three different collaborative robots is provided, to show how the methodology can be applied in real cases.

The complexity of modern industrial production systems and the persistent connectivity at the local level of manufacturing resources by means of IoT technologies are encouraging the study of increasingly flexible and reconfigurable control methods. Currently industrial software agents are mainly used for controlling job-shop organized systems, relying on negotiation mechanisms between Product agents and Resource agents. In this paper instead, we aim to develop a distributed production line controller, using agent-based technology for designing decentralized and communicating local state machines. The objective of the study is to obtain a global control system deriving from the interaction and exchange of information between software agents associated with each machine on the production line. The controller implemented has the purpose of eliminating the central infrastructure, generally present in industrial automation systems: the goal is to move the decision-making process locally by associating intelligent entities to each machine. The advantage of decentralization lies in the possibility of having a modular, flexible and reconfigurable line controller concept: indeed, there is no supervisor aware of the entire system to control. The agents can also collaborate for a line detection in case of very complex line without there being statistical evidence of performance deterioration. To validate the functionality of this approach, experimental tests were conducted in a virtual environment.

In order to make robot programming more easy and immediate, walk-through programming techniques can be exploited. However, a modification of a portion of the trajectory usually means to execute the path from the beginning. In this paper we propose a passivity-based framework to modify the trajectory online, manually driving the robot throughout the desired correction. The system follows the initial trajectory, encoded with Dynamical Movement Primitives, by setting high gains in the admittance control. When the human operator grabs the end-effector, the robot becomes compliant and the user can easily teach the desired correction, until he/she releases it at the end of the modification. Finally, the correction is optimally joined to the initial trajectory, restarting the path tracking. To avoid unsafe behaviors, the variation of the admittance parameters is performed exploiting energy tanks, in order to preserve the passivity of the interaction.

Accurate yield estimation is very important for improving the vineyard management, the quality of the grapes and the health of the vines. The most common systems use RGB image processing for achieving a good estimation. In order to collect images, robots or farming vehicles can be equipped with a RGB camera. In this paper, we propose a low-cost autonomous system which can navigate through a vineyard while collecting grape pictures in order to provide a yield estimation. Our system uses only a laser scanner to detect the row and follows it until its end, then it navigates towards the next one, exploiting the knowledge of the vineyard. The navigation algorithm was tested both in simulation and in a real environment with good results. Furthermore, a yield estimation of two different grape varieties is presented.

In this paper we consider a multi-robot system that shares the environment with external entities, and we propose a methodology for controlling the interaction with them. In particular, we consider the problem of achieving a desired dynamic interaction model, in such a way that the multi-robot system exchanges desired forces with external entities. This is obtained by introducing local deformations of the coupling actions among the robots. The proposed method ensures preservation of the passivity property, which provides safety guarantees in the interaction with the (possibly poorly known) external entities.

In multi-robot systems passive interconnections among agents are often exploited to achieve a desired and robustly stable cooperative behavior. Nevertheless, the passivity constraint limits the kinds of behaviors that can be achieved. In this paper, we exploit the concept of energy tank for building a novel generalized interconnection that allows to impose any kind of dynamic coupling between two passive systems in a flexible way while preserving the passivity of the overall coupled system. The proposed strategy is validated by simulations and experiments.

In this paper we present a general framework for affective human-robot interaction that allows users to intuitively interact with a robot and takes into account their mental fatigue, thus simplifying the task or providing assistance when the user feels stressed. Interaction with the robot is achieved by naturally mapping user's forearm motion, detected with a smartwatch, into robot's motion. High-level commands can be provided by means of gestures. An approach based on affective robotics is used to adapt the level of robot's autonomy to the cognitive workload of the user. User's mental fatigue is detected from the analysis of heart rate, also measured by the smartwatch. The framework is general and can be applied to different robotic systems. In this paper, we consider its experimental validation on a wheeled mobile robot.

Simulation is the key technology to enhance the product and production engineering processes. This paper presents an example of application of the simulation to the virtual design and optimization of a industrial production line.

Modern manufacturing systems typically require high degrees of flexibility, in terms of ability to customize the production lines to the constantly changing market requests. For this purpose, manufacturing systems are required to be able to cope with changes in the types of products, and in the size of the production batches. As a consequence, the human-machine interfaces (HMIs) are typically very complex, and include a wide range of possible operational modes and commands. This generally implies an unsustainable cognitive workload for the human operators, in addition to a non-negligible training effort. To overcome this issue, in this paper we present a methodology for the design of adaptive human-centred HMIs for industrial machines and robots. The proposed approach relies on three pillars: measurement of user's capabilities, adaptation of the information presented in the HMI, and training of the user. The results expected from the application of the proposed methodology are investigated in terms of increased customization and productivity of manufacturing processes, and wider acceptance of automation technologies. The proposed approach has been devised in the framework of the European project INCLUSIVE.

In physical human-robot interaction, the coexistence of robots and humans in the same workspace requires the guarantee of a stable interaction, trying to minimize the effort for the operator. To this aim, the admittance control is widely used and the appropriate selection of the its parameters is crucial, since they affect both the stability and the ability of the robot to interact with the user. In this paper, we present a strategy for detecting deviations from the nominal behavior of an admittance-controlled robot and for adapting the parameters of the controller while guaranteeing the passivity. The proposed methodology is validated on a KUKA LWR 4+.

This paper presents TIREBOT, a novel tire-workshop robotic co-worker that can safely move in a tire workshop and assist the operator in lifting and transporting wheels among several working stations. A safe and cooperative navigation strategy based on the concept of danger field is illustrated. Finally, TIREBOT is experimentally evaluated in a real tire-workshop and used by real operator in order to assess the usability and the effectiveness of the robot in a real operating scenario.

In this paper we consider the problem of controlling the dynamic behavior of a multi-robot system while interacting with the environment. In particular, we propose a general methodology that, by means of locally scaling inter-robot coupling relationships, leads to achieving a desired interactive behavior. The proposed method is shown to guarantee passivity preservation, which ensures a safe interaction. The performance of the proposed methodology is evaluated in simulation, over large-scale multi-robot systems.

Admittance control is a widely used approach for guaranteeing a compliant behavior of the robot in physical human-robot interaction. When an admittance-controlled robot is coupled with a human, the dynamics of the human can cause deviations from the desired behavior of the robot, mainly due to a stiffening of the human arm, and thus generate high-frequency unsafe oscillations of the robot. In this paper we present a novel methodology for detecting the rising oscillations in the human-robot interaction. Furthermore, we propose a passivity-preserving strategy to adapt the parameter of the admittance control in order to get rid of the high-frequency oscillations and, when possible, to restore the desired interaction model. A thorough experimental validation of the proposed strategy is performed on a group of 26 users performing a cooperative task.

In this paper we address the problem of assigning a set of tasks to a set of Automated Guided Vehicles (AGVs), in a conflict-free manner. Specifically, we consider a system of multiple AGVs, moving along a predefined roadmap, and utilized for transportation of goods in automated warehouses. Sequential application of task assignment and path planning often gives rise to pathological situations, such as deadlocks, in which AGVs block each other, thus preventing tasks completion. In this paper we propose a method for assigning tasks while taking into account the subsequent path planning, encoding possible conflicts into a conflict graph, that is subsequently utilized for defining constraints of an optimization problem. Simulations are performed on maps of real industrial environments, to compare the proposed method with traditional task assignment.

In this paper, we propose a novel methodology for achieving complex dynamic behaviors in multirobot systems. In particular, we consider a multirobot system partitioned into two subgroups: 1) dependent and 2) independent robots. Independent robots are utilized as a control input, and their motion is controlled in such a way that the dependent robots solve a tracking problem, that is following arbitrarily defined setpoint trajectories, in a coordinated manner. The control strategy proposed in this paper explicitly addresses the collision avoidance problem, utilizing a null space-based behavioral approach: this leads to combining, in a non conflicting manner, the tracking control law with a collision avoidance strategy. The combination of these control actions allows the robots to execute their task in a safe way. Avoidance of collisions is formally proven in this paper, and the proposed methodology is validated by means of simulations and experiments on real robots.

The utilization of modular and reusable resources would reduce complexity and lead-time for the design of cyber-physical systems. Even if different theories have been proposed, there is not a general definition and metamodel applicable for reusable resources. Energetic approaches constitute the state of the art for modeling the dynamics of physical systems. Within this work, Power-Oriented Graphs energetic approach is adapted to cyber-physical systems in order to provide a definition for reusable resources. Eventually, a metamodel for reusable resources is proposed.

This paper introduces a control strategy for obtaining cooperative tracking of periodic setpoint trajectories in multi-robot systems. A heterogeneous group of robots is considered: a few independent robots are used as a control input for the system, with the aim of controlling the position of the remaining robots, namely the dependent ones. The control strategy presented in this paper explicitly considers changes in the communication topology among the robots. These changes happen as the system evolves, since robots are equipped with finite range communication devices.

Wave variables are a very popular approach for dealing with communication delay in bilateral teleoperation because of their effectiveness and of their simplicity. Nevertheless, the inherent dynamics of wave based communication channels is often deleterious for the transparency of the teleoperation system. Recently proposed architectures like TDPN, PSPM and two layers approach allow to achieve a high transparency at the price of a complex architecture, with some parameters to tune empirically. In this paper we propose a novel wave based architecture that blends the high performance that can be achieved by recently proposed architectures with the simplicity of wave based bilateral teleoperation.

This paper describes a walk-through programming technique, based on admittance control and tool dynamics compensation, to ease and simplify the process of trajectory learning in common industrial setups. In the walk-through programming, the human operator grabs the tool attached at the robot end-effector and “walks” the robot through the desired positions. During the teaching phase, the robot records the positions and then it will be able to interpolate them to reproduce the trajectory back. In the proposed control architecture, the admittance control allows to provide a compliant behavior during the interaction between the human operator and the robot end-effector, while the algorithm of compensation of the tool dynamics allows to directly use the real tool in the teaching phase. In this way, the setup used for the teaching can directly be the one used for performing the reproduction task. Experiments have been performed to validate the proposed control architecture and a pick and place example has been implemented to show a possible application in the industrial field.

Because of their simplicity, wave variables have become almost a standard strategy for stabilizing delayed bilateral teleoperation systems. However, the price to pay for a stable behavior is a degradation in the performance of the teleoperation system. Recently, more flexible and transparency oriented bilateral architectures have been proposed (e.g. TDPN, PSPM, Two-Layer approach) but they are complex to implement and to tune. In [1], a strategy for blending the high performance of the new control methodologies with the simplicity of wave based bilateral teleoperation has been proposed. Nevertheless, while appealing in terms of simplicity, this method is conservative in terms of the transparency that can be achieved. In this paper, we extend the architecture in [1] in order to optimize the use of the energy and for achieving a coupling that is as close as possible to the desired one while preserving the passivity of the overall system.

In this paper we consider the problem of coordinating the motion of a group of Automated Guided Vehicles (AGVs) utilized in industrial environments for logistics operations. In particular, we consider a hierarchical coordination strategy, where the environment is partitioned into sectors: coordination on the top layer defines the sequence of sectors to be traveled, while coordination on the bottom layer deals with traffic management inside each sector. In this paper we introduce a novel partitioning algorithm, that defines the sectors in a dynamic manner, taking into account both the shape of the (generally non-convex) environment, and the current distribution of the AGVs. This is achieved exploiting a clustering algorithm, and subsequently defining the sectors based on the geodesic distance.

This paper describes innovative sensing technologies and control techniques, that aim at improving the performance of groups of Automated Guided Vehicles (AGVs) used for logistics operations in industrial environments. We explicitly consider the situation where the environment is shared among AGVs, manually driven vehicles, and human operators. In this situation, safety is a major issue, that needs always to be guaranteed, while still maximizing the efficiency of the system. This paper describes some of the main achievements of the PAN-Robots European project.

In this paper we propose a novel algorithm for the dynamic routing of a group of Autonomous Guided Vehicles (AGVs) used for transporting goods in automatic warehouses. Our strategy allows to improve the efficiency of a fleet of AGVs in terms of delivery time and its computational burden is sufficiently small to be embedded in standard industrial traffic management system. The algorithm is validated in a small-scale automatic warehouse with real AGVs.

We present Timing Diagram Testing for Verification & Validation (T4V, which is red as "tav") for Industrial Automation Systems. T4V is our approach to address the problem of generating test sequence to verify & validate (V&V) industrial automation systems software. T4V aims to solve this problem by generating test sequences from the timing diagrams of software specifications. Then, run them in Real-Time (RT) onto the PLC, check part of their conformance on-the-run, save the test outlines, and automatically analyze the outlines through an algorithmic verification. We currently implemented T4V for IEC61131-3 platforms (e.g. Beckhoff TwinCAT3) and Rockwell Automation PLCs, but we are integrating it only in our testing and V&V platform for Beckhoff PLCs. We believe that T4V may simplify and/or face the challenges of V&V in order to enable a more efficient and effective testing. Moreover, we believe that it could help PLC providers to understand the needs of an environment with testing and V&V features integrated.

We present our Abstraction Layer Object-Oriented Architecture (ALOOA) and its application to Motion Control. This layer provides a higher level of abstraction than that provided by the well-known PLCOpen library. In fact, the proposed approach uses OO features (i.e. methods, inheritance, and polymorphism) which allow us to define a generic device of motion control, whose hardware-dependent implementation details are then developed with specific Function Blocks (FBs) and methods. We are currently developing and using in our software the ALOOA and its libraries. As result, we can create hardware-independent software applications. Additionally, we achieved a reuse degree of our code of about 70% and improved its maintainability. ALOOA approach could be used to simplify and/or fulfill the maintainability, life-cycle-management, and the specific-platforms-and-their-limitations challenges. Moreover, it could help the OO features to penetrate further into the PLC world.

Autonomous vehicles require advances sensing technologies, in order to be able to safely share the environment with human operators. Those sensing technologies are in fact necessary for identifying the presence of unforeseen objects, and measuring their position and velocity. Furthermore, classification is necessary for effectively predicting their behavior. In this paper we consider the presence of sensing systems both on-board each vehicle, and installed on infrastructural elements. While the simultaneous presence of multiple sources of information heavily improves the amount (and quality) of available data, it generates the need for effective data fusion and storage systems. Hence, we introduce a centralized cloud service, that is in charge of receiving and merging data acquired by different sensing systems. Those data are then distributed to the autonomous vehicles, that exploit them for implementing advanced navigation strategies. The proposed methodology is validated in a real industrial environment to safely perform obstacle avoidance with an autonomously driven forklift.

When teleoperating a multi-robot system it is useful to control the kind of behavior of the fleet depending on the environment it is moving in. In this paper, a novel bilateral control architecture for teleoperating a group of mobile robots is proposed. The user can command the robots both as a flexible and amorphous group and as a set of agents executing different trajectories for achieving a desired task, mimicking a conductor-orchestra paradigm. Exploiting passivity based control, we ensure a stable and safe behavior for the user. The proposed teleoperation strategy is validated by means of experiments.

This paper deals with a holistic approach to coordinate a fleet of automated guided vehicles (AGVs) in an industrial environment. We propose an ensemble approach based on a two layer control architecture and on an automatic algorithm for the definition of the roadmap. The roadmap is built by considering the path planning algorithm implemented on the hierarchical architecture and vice versa. In this way, we want to manage the coordination of the whole system in order to increase the flexibility and the global efficiency. Furthermore, the roadmap is computed in order to maximize the redundancy, the coverage and the connectivity. The architecture is composed of two layers. The low-level represents the roadmap itself. The high-level describes the topological relationship among different areas of the environment. The path planning algorithm works on both these levels and the subsequent coordination among AGVs is obtained exploiting shared resource (i.e., centralized information) and local negotiation (i.e., decentralized coordination). The proposed approach is validated by means of simulations and comparison using real plants. Note to Practitioners-The motivation of this work grows from the need to increase the flexibility and efficiency of current multi-AGV systems. In particular, in the current state-of-the-art the AGVs are guided through a manually defined roadmap with ad-hoc strategies for coordination. This is translated into high setup time requested for installation and the impossibility to easily respond to dynamic changes of the environment. The proposed method aims at managing all the design, setup and control process in an automatic manner, decreasing the time for setup and installation. The flexibility is also increased by considering a coordination strategy for the fleet of AGVs not based on manual ad-hoc rules. Simulations are performed in order to compare the proposed approach to the current industrial one. In the future, industrial aspects, as the warehouse management system, will be integrated in order to achieve a real and complete industrial functionality.

Decentralized control strategies for multirobot systems have been extensively studied over the past few years. Typically, these strategies aim at exploiting local interaction rules to regulate the overall state of the multirobot system toward a desired configuration, thus generating some desired coordinated behaviors, such as synchronization, swarming, deployment, or formation control. However, when considering the real-world application of multirobot systems, more complex cooperative dynamic behaviors are desirable. Along these lines, in this paper, we propose a methodology to control a multirobot system for cooperatively tracking arbitrarily defined periodic setpoint trajectories. This objective is fulfilled partitioning the multirobot system into independent robots (that can provide control inputs) and dependent robots (that are controlled through local interaction). The motion of the independent robots is then defined in such a way that, exploiting local interactions, the dependent robots are controlled to track the desired trajectories. The proposed control strategy is validated by means of simulations and experiments on real robots.

We developed an UML-State-charts Object Oriented Design Pattern for PLCs IEC61131-3. This PLC UML-State-chart Design Pattern aims to explore the advantage of Object Oriented Programming by IEC61131-3 in PLCs, and to provide a direct map of UML State-chart to PLC code. We illustrates the design pattern and its use through UML Class diagrams and an application example. This Design Pattern can be used to reduce the development time of State-charts in automation software. It can also lead towards further investigations in PLC Design Patterns that may improve the whole development of automation software.

This paper deals with decentralized coordination of Automated Guided Vehicles (AGVs). We propose a hierarchical traffic control algorithm, that implements path planning on a two layer architecture. The high-level layer describes the topological relationships among different areas of the environment. In the low-level layer, each area includes a set of fixed routes, along which the AGVs have to move. An algorithm is also introduced for the automatic definition of the route map itself. The coordination among the AGVs is obtained exploiting shared resources (i.e. centralized information) and local negotiation (i.e. decentralized coordination). The proposed strategy is validated by means of simulations using real plant.

Decentralized control of networked systems has been widely investigated in the literature, with the aim of regulating the overall state of the system to some desired configuration, thus obtaining coordinated emerging behaviors (e.g. synchronization, swarming, coverage, formation control) by means of local interaction. In this paper we introduce a methodology to solve a tracking problem, that is defining a decentralized control strategy for making a networked system follow an arbitrarily defined periodic setpoint function. The most suitable interconnection topology is defined together with the control law as the solution of a constrained optimization problem, in order to ensure asymptotic tracking. Simulations are provided for validating the proposed control strategy.

This paper deals with the automatic generation of a roadmap. We propose an approach to build a roadmap for Automated Guided Vehicles (AGVs) used for logistics operations in industrial environments. The algorithm computes a roadmap in such a way that the coverage, the connectivity and the redundancy of the paths are maximized. In this way the flexibility and the efficiency of the AGV system can be increased. The proposed approach is validated by means of comparison with different roadmaps manually built in real plants.

Networked systems and decentralized control strategies have been widely investigated in the literature, with the objective of obtaining coordinated emerging behaviors by means of local interaction. While typical approaches aim at solving regulation problems (e.g. synchronization, swarming, coverage, formation control) a few works have recently appeared that move towards the solution of more complex problems, such as tracking of arbitrary setpoint functions. Based on the formulation introduced in [1], this objective is obtained in this paper partitioning the networked systems into leaders (that can provide control inputs) and followers (that are controlled through local interaction). In this paper we provide a methodology for letting the leaders estimate the state of the followers in a decentralized manner: this estimate is then used for control purposes. Simulations are provided for validating the proposed control strategy.

Over the last few years, systems have become a combination of multiple disciplines, such as mechanical, electrical, electronics and software engineering. A great number of methods have been introduced to face the increasing complexity of mechatronic systems but all show difficulties on integrating the various methodologies and competences of the single disciplines. For this reason, we are going to propose a brand-new design methodology and we have started here from the identification of some fundamental tools.

Hardware-in-the-Loop (HIL) is an important strategy to test a control system on a model of the real plant. This is particular important in the engineering process related to machine development since it permit to save many resources wasted in the development of a real experiment. This paper discusses how the modular approach in system development (Machine Modular Development, MMD), can support the system engineer (SE) to deal with system complexity in achieving a good HIL structure for validating the automation software.

In this paper, we present a new impedance control strategy that allows to reproduce a time-varying stiffness. By properly controlling the energy exchanged during the action, we guarantee the system passivity for any choice of the stiffness matrix, especially in case of time-varying stiffness, and therefore a stable behavior of the robot both in free motion and in interaction with an environment.

In this paper we introduce a collision avoidance control strategy for groups of mobile robots moving in a three-dimensional environment, whose dynamics are described according to the Lagrangian model. The proposed strategy is based on the use of gyroscopic forces, that ensure obstacle avoidance without interfering with the convergence properties of the multi-robot system's desired control law. Moreover, we introduce a method to define the direction of the force in an optimal way, in order to introduce the smallest possible perturbation with respect to the desired behavior of the system. Collision avoidance and convergence properties are analytically demonstrated, and simulation results are provided for validation purpose.

Decentralized control of networked systems has been widely investigated in the literature, with the aim of obtaining coordinated emerging behaviors (e.g. synchronization, swarming, coverage, formation control) by means of local interaction. In this paper we consider the possibility of injecting external inputs into the networked system, in order to obtain more complex cooperative behaviors. Specifically, we introduce a strategy that makes it possible to control the overall state of the networked system by directly controlling only a subset of the networked agents, namely the leaders. Exploiting local interaction rules, it is possible to define the inputs for the leaders in such a way that each follower is forced to track a desired periodic setpoint.

The verification and validation (V&V) of the controllers for complex mechatronic devices is an important step to assure performance and quality of the overall system. In particular, in the field of manufacturing of automatic packaging machines, it is common practice postpone the development of the control system until the mechanical part of the machine is finalized. This fact have rose the issue about simulation techniques to support the controller V&V at early development stage of the machine, to parallelize the development of the control and the mechanics. In particular, the Hardware in the Loop (i.e. the connection of the real controller with a simulated model of the machine) is currently under consideration by several researchers for provide support to the V&V of the system. This paper presents a methodology for the development of a HIL simulation which aims to the V&V of the distributed control system at early development stage of a packaging machine.

Design of complex systems involving a number of experts from various fields necessarily includes modeling at different levels of abstraction. Modeling is particularly important in the initial phase of a joint project when all system requirements and constraints have to be clearly defined and understood by all the partners. Once an unambiguous structural model has been achieved and components interfaces fixed, design of components can be done independently. For the initial phase, a very simplified modeling methodology based on UML that can be easily understood and applied has been proposed. The application of the methodology has been presented through the design of full structural model of the infrastructure for precision farming. Modeled infrastructure is an open ICT hardware-software solution based on ISOBUS specification, that enables partial automation of tractors increasing safety and production efficiency. Model achieved through several steps presents a mutual understanding platform between the partners. Most importantly, a precise model has been achieved without the necessity of in deep study of UML by all the partners.

While RGB-D sensors are becoming more and more popular in mobile robotics laboratories, they are usually not yet adopted for industrial applications. In fact, in this field, depth measurements are generally acquired by means of laser scanners and, when visual information is needed, by means of stereo-cameras. The aim of this paper is to perform an experimental validation, to compare the performance of a stereo-camera and an RGB-D sensor, in a specific application: mobile robot localization for industrial applications. Experiments are performed exploiting artificial landmarks (defined by a self-similar pattern), placed in known positions in the environment.

In this paper we consider the global localization problem for an industrial AGV moving in a known environment. The problem consists of determining the pose of the vehicle without any prior information about its location. The vehicle is supposed to be equipped with a laser scanner that allows to measure the range and bearing of the vehicle with respect to a set of anonymous landmarks. A map with the positions of all landmarks in the environment is available to the localization system. We propose a novel algorithm for AGV self-localization based on landmarks identification that can take into account also false detections, very common in industrial environments. The pose is computed with a single scan (2D), without any sensor fusion. The performance of the proposed strategy is shown both by simulations and experiments on real industrial plants.

In this paper we propose an algorithm for coordinating a fleet of Automated Guided Vehicles (AGVs) that go through predefined paths in a dynamic industrial environment. Coordination diagrams are used to define a mapping between the configuration space of the fleet and a set of motion constraints that the vehicles must satisfy in order to avoid mutual collisions. The motion actions that maximize the advancement of the fleet while respecting the constraints are determined by a polynomial time heuristic algorithm.

In this paper we address the trajectory tracking problem for groups of mobile robots. We consider trajectories described by completely arbitrary shaped closed curves. The proposed control strategy is a completely decentralized algorithm, and does not require any global synchronization. The desired behavior is obtained by means of some properly designed artificial potential functions.

In this paper we describe a novel decentralized control strategy to realize formations of mobile robots. We first describe a methodology to obtain a formation with the shape of a regular polygon. Then, applying a bijective coordinates transformation, we show how to obtain a formation with an arbitrary shape. Our control strategy is based on the interaction of some artificial potential fields, but it is not affected by the problem of local minima.

In this paper we propose a methodology for coordinating a group of mobile robots following predefined paths in a dynamic industrial environment. Coordination diagrams are used for representing the possible collisions among the robots. Exploiting the structure of the industrial application we are dealing with, we propose an algorithm for efficiently composing the coordination diagram. Furthermore, we classify the possible collisions that can take place and the induced geometry of the resulting coordination diagram. Finally, we exploit this information for developing a planning algorithm that allows to coordinate the robots and to take into account unexpected events that can occur in an industrial environment.

In this paper we address the problem of formation control of a group of robots that exchange information over a delayed communication network. We consider the Virtual Body Artificial Potential approach for stabilizing a group of robots at a desired formation. We show that it is possible to model the controlled system as a set of elements exchanging energy along a power preserving interconnection structure. We exploit the scattering framework to stabilize the robots in the desired formation independently of any delay in the communication of the information.

After stability, transparency is the major issue in the design of a telemanipulation system. In this paper, we exploit the behavioral approach in order to provide an index for the evaluation of transparency in port-Hamiltonian-based teleoperators. Furthermore, we provide a transparency analysis of packet switching scattering-based communication channels.

The paper presents advanced issues in modelling and simulation of complex packaging line. In particular, we developed a theoretical model of a line with two machines and a buffer, which is a simplified version of a real packaging line from Tetra Pak company. The paper reports also about simulation results that confirm theoretical supposals.

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

In several applications involving haptic interfaces it can be desirable to scale the interaction force perceived by the user. The most intuitive approach is to change the stiffness of the virtual environment but, unfortunately, changing the physical parameters that characterize a virtual environment is a potentially destabilizing action. In this paper we embed in the intrinsically passive haptic scheme recently proposed in S. Stramigioli et al. (2005) a power scaling interconnection that allows to scale the force perceived by the user while preserving the passivity, and consequently the stable behavior, of the overall system

Passivity based bilateral telemanipulation schemes are often subject to a position drift between master and slave if the communication channel is implemented using scattering variables. The magnitude of this position mismatch can be significant during interaction tasks. In this paper we propose a passivity preserving scheme for compensating the position drift arising during contact tasks in port-Hamiltonian based telemanipulation improving the kinematic perception of the remote environment felt by the human operator

The aim of the paper is to provide a practical method to introduce design principles typical of the object-oriented approach, like “design by extension”, to the application domain of manufacturing systems control design. The proposed method is based on a domain-specific extension of the modeling language UML and on the formalization of design models as transition systems for verification purposes. Object-oriented models, formalized according to the proposed semantics, can be analyzed with model checking techniques in order to verify the behavioral conformity of object classes, according to a notion of substitutability which is defined in the paper specifically for the proposed modeling language.

The aim of this paper is to provide a unified language for modeling both control software and physical plants in real time control systems. This is done by embedding the bond graph modeling language for physical systems into the UML-RT framework, widely used to model distributed real-time software.

After stability, transparency is the major issue in the design of a telemanipulation system. In this paper we exploit a behavioral approach in order to provide an index for the evaluation of transparency in port-Hamiltonian based teleoperators. Furthermore we provide a transparency analysis of packet switching scattering based communication channels.

In several applications involving bilateral telemanipulation, master and slave robots act at different power scales (e.g. telesurgery). The aim of this paper is to embed power scaling into port-Hamiltonian based bilateral telemanipulation schemes, In order to deal with nonnegligible transmission delays we propose a novel scattering based communication strategy to properly scale the power exchanged by master and slave while preserving a stable behavior of the overall scheme.

In this paper, we present a novel way to approach the interconnection of a continuous and a discrete time physical system first presented in . This is done in a way which preserves passivity of the coupled system independently of the sampling time T. This strategy can be used both in the field of telemanipulation, for the implementation of a passive master/slave system on a digital transmission line with varying time delays and possible loss of packets (e.g., the Internet), and in the field of haptics, where the virtual environment should 'feel' like a physical equivalent system.

The paper describes a methodological framework that aims to apply formal design and verification techniques in the development of industrial control systems, with particular regard to the domain of manufacturing machines. The methodology is based on an object-oriented approach, revisited in a mechatronic perspective, and is supported by the specification methods proposed by the UML language. This language, opportunely adapted to the application domain, permits to describe control system design models which are modular, reusable and independent from the implementation architecture. The implementation domain is taken into account only during the verification phase, in which it is necessary to identify a correct semantical interpretation according to the execution model of the computational platform. In particular, the different frameworks of the industrial standards IEC 61131-3 and IEC 61499 are considered and compared with each other. The paper shows that formal verification techniques can be applied to prove the correctness of the design specification or to guide its iterative refinement, thanks to a translation of the O-O model into the input language of the model checking tool SMV.

In this paper we present an intrinsically passive telemanipulation scheme over a digital transmission line Internet-like. We present an analysis of the energetic behavior of the communication line both in case of loss of packages and in case of variable delay. The sample data nature of the passive controller is explicitly taken into account following the approach outlined.

In this paper two problems arising in the digital passive scheme for telemanipulation presented in are addressed. At first, we show how to preserve system passivity in presence of quantization error introduced by position sensor (i.e. encoders) by introducing energy dissipation. Then, we introduce a scheme for a redundant communication channel that will compensate for missed packets improving performances while preserving passivity of the overall scheme.

In this paper the problem of delayed virtual environments in haptics is addressed. We show that the approach outlined is no longer passive in case of (computational) delay on the output of the virtual environment. Passivity can be recovered using scattering theory; a discretization algorithm which leads to a discrete passive port-Hamiltonian systems with respect to any delay on the output is proposed.

This paper presents a practical experiment on the use of visual servoing for robotic tracking and manipulation of objects moving on a plane. In this work, the image is acquired from the camera mounted on the end-effector of a 6 DOF industrial robot, and processed on a standard PC-based vision system in order to close the visual servoing loop with a PID based controller. The PID has been implemented with a variable structure, modified according to the estimated velocity of the target, in order to achieve a good step response and to eliminate steady-state error with a moving target. The possibility to perform a stable tracking and to estimate the target dynamics allows also to grasp the object with a prediction based trajectory planning.

This paper presents a novel approach to the interconnection of a continuous time and a discrete time physical system. This is done in a way which preserves the passivity of the coupled system independently of the sampling time. A direct application in the field of haptic displays, where a virtual environment should feel like equivalent physical systems, is presented.