José L. Poza

Agent-based distributed architecture for mobile robot control

Mobile robots are physical agents that move and interact continuously while embedded in a dynamic environment. Communications can be one of the most difficult parts of building robot architecture because of the increasing complexity of sensor and actuator hardware, and the interaction between intelligent features and real-time constraints. Currently, hybrid architectures offer the most widespread solutions for controlling intelligent mobile robots. This paper deals with the communications framework necessary to design and implement these architectures. The main goal of this work is to design a modular and portable architecture that allows the development of robot control systems. A multi-level and distributed architecture based on the reactive/deliberative paradigm is presented. Its main components are mobile software agents that interact through a distributed blackboard communications framework. These agents can be run on onboard processors, as well as on fixed workstations depending on their real-time restrictions. The presented control architecture has been tested in a real mobile robot and results demonstrate the effectiveness of distributing software agents to guarantee hard real-time execution.

Communication jitter influence on control loops using protocols for distributedreal-time systems on can bus

Abstract The paper focuses on the behaviour of distributed control loops affected by the jitter derived from the communication latencies of CAN. The work uses a hybrid communication protocol between a pure TTP (Time Triggered Protocol) and ETP (Event Triggered Protocol), a reasonable choice for distributed real-time systems, as a reactive mobile robot. This hybrid protocol shares the time-slots to reduce the jitter effects. This guarantees fixed transmissions latencies for periodic messages, allowing also sporadic messages transmission, as is the case of alarms, or in long data blocks, by means of using shared TTP slots. The protocol assigns private time slots for realtime messages, and shared time slots for non real-time messages. Also, the protocol uses only a simple and static table. The implementation is validated by means of a quantitative comparison, using the data obtained from a simulation of a typical distributed control system consisting of an industrial process and a remote controller forming a closed control loop that uses CAN as its communication channel. In the simulation, the effect of the jitter introduced into the control loop is measured for the above mentioned communication protocols, and the obtained results from this simulation are also discussed.

QoS-Based Middleware Architecture for Distributed Control Systems

This paper presents an implementation of a middleware architecture to control distributed systems. The main objective is providing a QoS level between the communications layer and the control layer. This architecture is based on the use of a hierarchical communications structure called “logical namespace tree” and a structured set of control processes interconnected, called “logical sensors graph”. This architecture is named Frame Sensor Adapter Control (FSA-Ctrl). In this architecture both: communication layer and control layer can manage the QoS policies. The communication layer is based on the Data Distribution Service (DDS), a standard proposed by Object Management Group (OMG). Control layer is derived from the Sensor Web Enablement (SWE) model proposed by Open Geospatial Consortium (OGC). By means of QoS policies, control components can take important decisions about distributed questions, like components mobility or information redundancy detection.

From the Queue to the Quality of Service Policy: A Middleware Implementation

Quality of service policies in communications is one of the current trends in distributed systems based on middleware technology. To implement the QoS policies it is necessary to define some common parameters. The aim of the QoS policies is to optimize the user defined QoS parameters. This article describes how to obtain the common QoS parameters using message queues for the communications and control components of communication. The paper introduces the “Queue-based Quality of Service Cycle” concept for each middleware component. The QoS parameters are obtained directly from the queue parameters, and Quality of Service Policies controls directly the message queues to obtain the user-defined parameters values.

REAL-TIME CONTROL AND MONITORING IN A CONTAINER TERMINAL

Abstract Management, control, monitoring and detecting errors in distributed industrial systems is strongly dependent on the physical and functional topology. This paper describes a solution to this problem by monitoring the event channel instead of monitoring the nodes. Multi-agent architecture is an appropriate framework to this kind of systems because it optimizes the complete yard management and uses an event-oriented channel to support the communication between agents.

Communication system architecture to manage a containers terminal

Currently, containers are used in the transport of products because of the point-to-point service they offer. By using specialized cranes, operation in maritime transport and land transport can be achieved quickly. To optimize the operation costs, the whole management of terminal is computerized proportionally with the complexity of the problem. The multi-agent system paradigm seems suitable to solve the computational problem. The communication between agents and the corresponding data warehouse is made by means of a number of content-oriented communication channels. For supplying an organized message routes to the system, an event oriented communication system has been developed. The communication channels determine the communication system architecture. This paper describes how common communications architecture for agents can facilitate the management of an industrial system. The aim is to separate the agents of the communications. The communications system used is based on the distributed blackboard architecture.

An architecture to control mobile robots by means of code delegation and multi-agent systems

Abstract In this paper is presented an architecture to control mobile intelligent robots based on the hybrid reactive/deliberative paradigm. This architecture is multi-level and distributed, and their main components are mobile software agents that interact through a distributed blackboard communications system. These agents can run on processors on board or on fixed workstations depending on its real time constraints.

Adding an Ontology to a Standardized QoS-Based MAS Middleware

In a Multi-Agent system, middleware is one of the components used to isolate control and communications. The use of standards in the implementation of an intelligent distributed system is always advantageous. This paper presents a middleware that provides support to a multi-agent system. Middleware is based on the standard Data Distribution Services (DDS), proposed by Object Management Group (OGM). Middleware organizes information by tree based ontology and provides a set of quality of service policies that agents can use to increase efficiency. DDS provides a set of quality of service policy. Joining quality of service policy and the ontology allows getting many advantages, among others the possibility of to conceal some details of the communications system to agents, the correct location of the agents in the distributed system, or the monitoring agents in terms of quality of service. For modeling the middleware architecture it has used UML class diagrams. As an example it has presented the implementation of a mobile robot navigation system through agents that model behaviors.

Wall/corner classification. A new ultrasonic amplitude-based approach

Abstract In this work, a simple model of the amplitude response of the ultrasonic echoes is used to assess about the nature of the detected objects, enabling its classification between walls and corners. The ultrasonic signal comes from a unique pair of rotating emitter/receiver transducers. The amplitude of the echoes together with their time of flight are used in a simple data fusion process that exploits the geometric features of the two main types of reflectors-walls and corners-to identify the detected objects in a scene, locating them into the map with reasonably good precision. To apply the amplitude-based model, only one parameter of the environment is needed: the reflection coefficient of each surface. The data fusion process can be carried out using different algorithms. Each of these algorithms has its pros and cons, yielding different success percentages and different computational costs In this paper, a comparative study on two classification algorithms is also presented. The first one is based directly on the amplitude model, and the other is based on the k-neighbours algorithm, widely used in pattern recognition. Finally, a comparative table shows the results obtained in the classification of targets with distances from sensor ranging between 0.5 to 4 metres, and with incidence angles ranging between 20° to 70°

Adding real data to detect emotions by means of smart resource artifacts in MAS

This article proposes an application of a social emotional model, which allows to extract, analyse, represent and manage the social emotion of a group of entities. Specifically, the application is based on how music can influence in a positive or negative way over emotional states. The proposed approach employs the JaCalIVE framework, which facilitates the development of this kind of environments. A physical device called smart resource offers to agents processed sensor data as a service. So that, agents obtain real data from a smart resource. MAS uses the smart resource as an artifact by means of a specific communications protocol. The framework includes a design method and a physical simulator. In this way, the social emotional model allows the creation of simulations over JaCalIVE, in which the emotional states are used in the decision-making of the agents.