Abstract: This paper introduces a flexible hardware and software architecture for a smart video sensor. This sensor has been applied in a video surveillance application where some of these video sensors are deployed, constituting the sensory nodes of a distributed surveillance system. In this system, a video sensor node processes images locally in order to extract objects of interest, and classify them. The sensor node reports the processing results to other nodes in the cloud (a user or higher level software) in the form of an XML description. The hardware architecture of each sensor node has been developed using two DSP processors and an FPGA that controls, in a flexible way, the interconnection among processors and the image data flow. The developed node software is based on pluggable components and runs on a provided execution run-time. Some basic and application-specific software components have been developed, in particular: acquisition, segmentation, labeling, tracking, classification and feature extraction. Preliminary results demonstrate that the system can achieve up to 7.5 frames per second in the worst case, and the true positive rates in the classification of objects are better than 80%.
Abstract: 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(1) 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. (c) 2007 Elsevier Ltd. All rights reserved.
Abstract: This paper analyzes the use of ultrasonic echo amplitudes to evaluate the characteristics of the detected surfaces (such as distinguishing between walls and corners). The shape and surface characteristics of the environment, such as roughness or absorption coefficient, as well as the distance and the angle of incidence, have high influence on the amplitude of the echoes. As a consequence, the amplitude of the received echoes has received little attention from robotic researchers. Instead, time-of-flight (ToF) has been used as the main source of information of the environment. It is also well known that the shape of the echoes of a corner is the same as that of a wall [IEEE Trans. Pattern Anal. Mach. Intell. (PAMI), 12 (1990) 560]. Several authors have proposed special multi-transducer configurations to avoid this problem. This paper studies the amplitude of received echoes and presents a simple model to predict the shape and amplitude of echoes received from different materials in environments composed of walls and corners. Using this model, and analysing the amplitude of the echoes it is possible to distinguish between walls and corners in a single scan of a single ultrasonic transducer pair. The parameters of the model were obtained from tests performed on different materials and surfaces. The last section of the paper shows the experimental results of the wall-corner classifications obtained in real tests during the walk of a mobile robot. The results suggest that the method proposed can be of great interest for map building in robotics. (C) 2004 Elsevier B.V. All rights reserved.
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 real-time 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. Copyright (C) 2003 IFAC.
Abstract: This paper(1) presents a study about the amplitude of ultrasonic echoes and a simple model is proposed to predict the shape and amplitude of echoes received from different materials in environments composed of walls and corners. Using this model is possible to distinguish between walls and corners, in a single circular scan of a single ultrasonic transducer pair The parameters of the model have been derived after exhaustive tests performed on different materials and surfaces. Finally, the experimental results of wall-corner classifications obtained in real tests during the walk of a mobile robot are presented. The results suggest that the proposed method can be of great interest for map building in robotics.
Abstract: This paper(1) highlights the characteristics of software and hardware architecture for intelligent sensor and actuators in a distributed system as a mobile robot. The work focuses on reactive architectures and the method to interchange sensor and control data among distributed nodes. The work proposes a hybrid communication protocol between a pure TTP (Time Triggered Protocol) and ETP (Event Triggered Protocol) and reactive architecture for dual devices (sensor/actuator). Finally, a case study and experimental results with message latencies are presented.
Abstract: The amplitude response of infrared (IR) sensors based on reflected amplitude of the surrounding objects is non-linear and depends on the reflectance characteristics of the object surface. As a result, the main use of IR sensors in robotics is for obstacle avoidance. Nevertheless, their inherently fast response is very attractive for enhancing the real-time operation of a mobile robot in, for instance, map building tasks. Thus, it seems that the development of new low-cost IR sensors able to accurately measure distances with reduced response times is worth researching. In this paper, a new IR sensor based on the light intensity back-scattered from objects and able to measure distances of up to I m is described. Also, the sensor model is described and the expected errors in distance estimates are analysed and modelled. Finally, the experimental results obtained are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.
Abstract: Mobile robotics development provides an excellent opportunity to experiment with various architectural solutions for distributed real-time systems. This is because of the increasing complexity of sensor and actuator hardware, and the interaction between intelligent features and real-time constraints. Currently, hybrid control structures seem to be the most widespread method of control. This paper describes a communications scenario resulting from hybrid structures. The YAIR robot and its communication infrastructure is described by addressing the control problems found and the solutions adopted. This paper presents a case study of implementing a hybrid communications system using the CAN bus. The worst-case message delay analysis for this bus is also presented, as well as the structure of identifiers defining its semantic possibilities. The deliberative part of the communication system is a developed object bus on TCP/IP protocol networks. The programming interface at this level takes the form of a distributed blackboard with extended properties such as a bind-notification mechanism and a temporal register recording the temporal firewall of information supplied. The overlap between both communication systems is a gateway service performing bi-directional mirroring over a set of CAN identifiers. Finally, a system test is presented. The test emphasises the intra-level gateway for validating performance and time expressiveness. (C) 2002 Elsevier Science Ltd. All rights reserved.
Abstract: This paper introduces an embedded architecture and the low-level video processing algorithms developed for an intelligent node that is a part of a distributed intelligent sensory network for surveillance purposes. In this paper, details of the architecture developed for this node are given, together with the low-level video processing algorithms used, as well as the results obtained after their implementation. The video board has been developed using two DSP processors for video processing tasks, as well as a FPGA dedicated to image capture (VGA size) and to dispatch them to the DSP processors. The low-level software includes acquisition, segmentation, labeling, tracking and classification of detected objects into three main categories: Person, Group and Luggage. Also, additional features are extracted from each object in the frame. The unit has to communicate the classification results and the main features obtained using XML streaming to upper levels, as well as the processed frames, using a JPEG stream. All these functionalities are currently running in the built prototypes.
Abstract: This paper describes an implementation of a region- based memory manager that performs the allocation and deallocation in constant-time. Also, aditional functional- ity for generating arrays which can grow arbitrarily has been implemented. Thus, external fragmentation is over- comed, and the appearance of memory leaks has been considerably reduced. All these features make this alloca- tor particularly useful for computer vision applications. The main goal has been to replace the general purpose allocator on some critical places in order to remove frag- mentation and improve performance. The use of Regions also reduces programmer burden. The main disadvantage of this method is that it leads to a higher memory con- sumption peaks than general-purpose allocators. System developers need to stablish an upper bound for the max- imum memory that can be allocated at once. In this pa- per, the performance of our approach has been compared against an architecture-optimized general purpose mem- ory allocator in a real-time vision application.
Abstract: Geometric representation of the environment, known as mapping, plays an important role in mobile robotics as it support various tasks such as localization, path planning and motion control. Line models represent a popular approach to represent the geometric features of the environment. The mapping problem gives rise to a variety of solutions for using different exteroceptive sensors (sonar infrared, laser vision, etc.). One of the possible choices is to use an infrared sensor (IR sensor). These devices art, inexpensive, practical and widely available. Infrared sensors are largely used in obstacle avoiding processes because they are fast and cheap, and require only simple signal processing. Although the collision avoidance routine has received good attention for many years, the infrared feature mapping has been neglected. A problem with this kind of sensor is its short range (about one meter). This problem forces to an incremental mapping approach, so the robot has to move and concurrently model the environment. In this paper we present an IR sensor able to measure distances based on the light that is back-scattered from objects. This IR sensor is used for line-based map building purposes, so we also present a methodology for line extraction, range data clustering and line segmentation. The experimental test has been carried out in a long corridor and results show the usefulness of the IR sensor and the methodology we propose for feature extraction and line-based mapping processes.
Notes: 13th IEEE International Conference on Emerging Technologies and Factory Automation, Hamburg, GERMANY, SEP 15-18, 2008
Abstract: Ultrasound sensors, despite their low cost, are less common than other sensors used for robot localization. This is because its main drawback: The lack of reliable bearing information. We introduce a rotary ultrasonic sensor able to extract features in a 360 degrees- scan and classify them as wall or corner For robot localization purposes, these features are matched with a set of line-features stored on a priori known map. The localization process is carried out through an Extended Kalman Filter that fuses data provided by a dead-reckoning system with measurements data provided by the rotary sonar This paper also presents techniques we use to classification the detected features. The experimental test carried out in a long corridor shows the usefulness of the rotary sensor for feature extraction and robot localization process. The results show that localization error is in subcentimeter range.
Notes: 12th IEEE International Conference on Emerging Technologies and Factory Automation, Patras, GREECE, SEP 25-28, 2007
Abstract: Estimation of objects in a 3D space is a fundamental problem in computer vision and robotics. This paper describes an algorithm and its implementation for a vision module as a sensor of a biped robot (YABIRO). The embedded vision sensor is able to estimate the position of objects like spheres in 3D space. Objects are defined with their size and color in a model. The vision sensor detects the positions or at least the directions to the objects and stores them in a history. The algorithm includes a new voting system for detected objects, based on how trustable the detection was, and a new edge filter to terminate edges on the circle border for the circle detection. The systems frame rate depends on the area of interest and lies between 5 Hz and 20 Hz. With a mechanical size of 36x32 mm it is smaller than a matchbox.
Notes: 4th International Workshop on Intelligent Solutions in Embedded Systems (WISES 2006), Vienna, AUSTRIA, JUN 30, 2006
Abstract: In this paper, an advanced architecture for embedded control systems to be used in a mobile biped robot, called YABIRO-II, is presented. The robot has a total height of 55 cm, and a total weight of 4 Kg. Also, it has a total of 27 degrees of freedom (DOF). This number of joints enables YABIRO-II to produce many different gait configurations, and is also suitable to test and validate the proposed distributed control architecture. This distributed architecture has been designed to obtain a high technological robot platform. Also, a real time software platform has been also developed to control the robot from an embedded-PC node, helped by a reliable dual-CAN network to distribute all the robot information between sensors and actuators nodes.
Notes: 6th IEEE/RAS International Conference on Humanoid Robots, Genoa, ITALY, DEC 04-06, 2006
Abstract: This paper introduces the basis of a graphical software application, designed for low cost hardware, as a flexible platform to work on mobile robots. VirtualRobot has proven to be a useful tool in mobile robot and sensor simulation. In this paper, some simulations of mobile robot applications will be shown with the help of VirtualRobot Simulator.
Abstract: This paper describes the design and implementation of a CAN Time-Triggered based communication protocol named SCoCAN, (Shared Channel on CAN), intended for use in distributed control systems, as is the case of autonomous mobile robots. This protocol enables real time communication between different intelligent nodes (sensors, actuators and controllers). The SCoCAN protocol has been implemented in the YAIR robot nodes, producing minimum jitter in the sensor-control-actuator loops. This hybrid protocol follows a scheme between pure TTP (Time Triggered Protocol) and ETP (Event Triggered Protocol), that guarantees acceptable response times and is deterministic.
Notes: 10th IEEE International Conference on Emerging Technologies and Factory Automation, Catania, ITALY, SEP 19-22, 2005
Abstract: In this paper we present a real time architecture for embedded control systems to be used in a mobile biped robot called YABIRO(1). The robot has a total of 14 degrees of freedom (DOF). This number of joints enables YABIRO to produce many different gait configurations, and is also suitable to test and validate the proposed real time control architecture. A new embedded intelligent motor controller (IMCD) has been also designed and implemented in each joint node of the distributed architecture, to work inside the real time network.
Notes: IEEE International Symposium on Computational Intelligence in Robotics and Automation, Espoo, FINLAND, JUN 09-30, 2005
Abstract: This paper(1) presents a study about the amplitude of ultrasonic echoes and a simple model is proposed to predict the shape and amplitude of echoes received from different materials in environments composed of walls and corners. Using this model is possible to distinguish between walls and corners, in a single circular scan of a single ultrasonic transducer pair The parameters of the model have been derived after exhaustive tests performed on different materials and surfaces. Finally, the experimental results of wall-corner classifications obtained in real tests during the walk of a mobile robot are presented. The results suggest that the proposed method can be of great interest for map building in robotics.
Notes: 11th International Conference on Advanced Robotics (ICAR 2003), COIMBRA, PORTUGAL, JUN 30-JUL 03, 2003
Abstract: This paper(1) highlights the characteristics of software and hardware architecture for intelligent sensor and actuators in a distributed system as a mobile robot. The work focuses on reactive architectures and the method to interchange sensor and control data among distributed nodes. The work proposes a hybrid communication protocol between a pure TTP (Time Triggered Protocol) and ETP (Event Triggered Protocol) and reactive architecture for dual devices (sensor/actuator). Finally, a case study and experimental results with message latencies are presented.
Notes: 11th International Conference on Advanced Robotics (ICAR 2003), COIMBRA, PORTUGAL, JUN 30-JUL 03, 2003
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 real-time 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. Copyright (C) 2003 IFAC.
Notes: 5th IFAC International Symposium on Intelligent Components and Instruments for Control Applications, Aveiro, PORTUGAL, JUL 09-11, 2003
Abstract: This paper describes a communication system called SC (Sistema de Comunicaciones) that is suitable for real-time systems with distributed sensory architecture. This system has been implemented in the YAIR robot, an autonomous robot with intelligent sensors that produces different measurements about the environment and its position within it. To guarantee good response times, the sensory modules are connected using the CAN bus. The robot’s main controller executes a control algorithm that can be decomposed into smaller parts using a communications server. Thus, the execution can be shared between different processors connected through an Ethernet network. Copyright (C) 2000 IFAC.
Notes: 6th IFAC Workshop on Algorithms and Architectures for Real-Time Control (AARTC 2000), PALMA DE MALLORCA, SPAIN, MAY 15-17, 2000
Abstract: In the last few years, research in mobile robot architectures have increased because the need of autonomy. This research has been addressed mainly into multisensor robots to enhance the perception skills and fusing the data, obtaining coherency and good quality information. In this work, a robot architecture under development called YAIR is presented.YAIR (Yet Another Intelligent Robot) is an experimental, multisensor prototype of autonomous robot that is currently being developed to serve as a platform to experiment with different real time issues, as distributed sensor systems, data fusion algorithms, operating systems, field buses and robot control. This paper focuses into the control architecture based on behaviours and with a decentralised selection mechanism. The sensor modules in the robot are the described below and all of them are connected to a main controller using the CAN bus. Copyright (C) 1998 IFAC.
Notes: 5th IFAC Workshop on Intelligent Manufacturing Systems (IMS 98), GRAMADO, BRAZIL, NOV 09-11, 1998
Abstract: In this paper an ultrasonic sensor is presented, aimed to map building in autonomous robot applications. By means of a rotary movement the sensor can be settled up to 200 angular positions. The data processing performed in the sensor module gives more elaborated data than the usual ToF ultrasonic sensor systems and it is possible to detect all objects placed in the scenario with its signal amplitude value. Due to the quality of data is possible to reduce the amount of angular readings required to construct the map. As results indicate it is possible to obtain good maps using only a very reduced set of readings. Copyright (C) 1998 IFAC.
Abstract: In this paper an ultrasonic sensor is presented, aimed to map building in autonomous robot applications. By means of a rotary movement the sensor can be settled up to 200 angular positions. The data processing performed in the sensor module gives more elaborated data than the usual ToF ultrasonic sensor systems and it is possible to detect all objects placed in the scenario with its signal amplitude value. Due to the quality of data is possible to reduce the amount of angular readings required to construct the map. As results indicate it is possible to obtain good maps using only a very reduced set of readings. Copyright (C) 1998 IFAC.
Notes: 3rd IFAC Symposium on Intelligent Autonomous Vehicles 1998 (IAV 98), MADRID, SPAIN, MAR 25-27, 1998
Abstract: In this paper the results in the development of a sonar array sensor for the use in mobile robot platforms are presented. The work involves hardware development and signal processing techniques for the reconstruction of the scene. The developed sensor uses an array of four transducers to improve the distance measurement and angular resolution. Its angular response has some sidelobes around the main lobe. The main advantage of this approach is a sharper main lobe, compared with the main lobe of the only one pair emitter-receiver device. However, the lateral sidelobes have significant amplitude and can produce false peaks detection. This problem can be addressed using adequate deconvolution methods. This approach decreases the amplitude of the sidelobes and produces a high quality data with low angular ambiguity. This allows map building with better data, obtaining good results in real environments. The tests performed show good enough obstacle detection results in a normal office environment. The signal processing treatment is adequate for the DSP implementation allowing the use of the sensor on a real-time mobile vehicle. The use of the measurements in sensor fusion levels for the map building, reduces the complexity and uncertainty of this process, allowing a simple signal-fusion level and increasing the quality of the final map. Copyright (C) 1998 IFAC.
Notes: IFAC Workshop on Intelligent Components for Vehicles, SEVILLE, SPAIN, MAR 23-24, 1998
Abstract: Yet Another Intelligent Robot (YAIR) is a multisensor prototype of autonomous robot that is currently being developed. The main purpose of this experimental robot is to provide a general platform to research about different real time issues such as distributed sensor systems, data fusion algorithms, operating systems and field buses. This paper describes the robot architecture developed around the CAN (Controller Area Network) bus standard. The paper also analyzes the operational modes that can be found in the robot. Seven basic modes have been defined. Each mode is related with its different movement types and the specific tasks than can be programmed. A preliminar study of the real time characteristics for the different message sets used in each operational mode is also presented.
Notes: 3rd IFAC Symposium on Intelligent Components and Instruments for Control Applications (SICICA 97), ANNECY LE VIEUX, FRANCE, JUN 09-11, 1997
