A Constraint-Based Robotic Soccer Team

It is a challenging task for a team of multiple fast-moving robots to cooperate with each other and to compete with another team in a dynamic, real-time environment. For a robot team to play soccer successfully, various technologies have to be incorporated including robotic architecture, multi-agent collaboration and real-time reasoning. A robot is an integrated system, with a controller embedded in its plant. A robotic system is the coupling of a robot to its environment. Robotic systems are, in general, hybrid dynamic systems, consisting of continuous, discrete and event-driven components. Constraint Nets (CN) provide a semantic model for modeling hybrid dynamic systems. Controllers are embedded constraint solvers that solve constraints in real-time. A controller for our robot soccer team, UBC Dynamo98, has been modeled in CN, and implemented in Java, using the Java Beans architecture. A coach program using an evolutionary algorithm has also been designed and implemented to adjust the weights of the constraints and other parameters in the controller. The results demonstrate that the formal CN approach is a practical tool for designing and implementing controllers for robots in multi-agent real-time environments. They also demonstrate the effectiveness of applying the evolutionary algorithm to the CN-modeled controllers.     

基于自抗扰控制器的机器人无标定手眼协调

研究机器人无标定手眼协调问题.分析了图像空间到机器人操作空间之间的非线性映 射关系,并把非线性的映射关系看成是系统的未建模动态.基于自抗扰控制器思想,通过对系统 未建模动态和外扰的补偿,完成了不依赖于任务的无标定手眼协调控制器的设计,实现了广泛意 义的机器人无标定手眼协调控制.仿真和实验结果表明了该方法的有效性.     

Design and Implementation of a Low Cost Multi-Fingered Robotic Hand Using a Method of Blocks

The control of a mechanical robotic hand is plagued by an inability to derive accurate dynamic models of such a mechanism. The aspects of static and kinetic friction are major obstacles in the control of a mechanical hand. This paper presents a fuzzy-like based controller and its implementation for a low cost robotic hand. The controller has the ability to automatically regenerate the member set during the translation of any arbitrary joint in a robotic hand. A series of simulations has been conducted that illustrate the effectiveness of this controller for providing smooth translation independent of frictional forces.The implementation of the controller used here is based on an IBM compatible computer using a custom designed acquisition/conversion interface and a mechanical hand assembly. A hand with a progressively linked finger structure has been used for simplicity. The acquisition system used here allows bidirectional communication with the sensors and actuators of the hand.A series of experiments have been conducted which verify that the method of blocks was successful for controlling joint position. The simulation results include both fine movements, needed for dexterity, and gross movements that can be used for grasping. This robotic hand produces good results in a low cost implementation.     

FT-AVS: a Fault-tolerant Architecture for Real-Time Active Vision

The nature of most problems addressed by robotics requires that robotic systems possess real-time properties. Additionally, as a result of steady increases in power and decreases in the cost of technology, it has become feasible to integrate sophisticated vision systems into robotic tasks. This can be seen by the recent interest in active vision.The purpose of this paper is two-fold: we first present a novel architecture for real-time active vision systems, and then enhance the architecture with a unified approach to fault tolerance. Our system is designed modularly in order to enable the flexible addition of hardware and software redundancy and also to allow reconfiguration when and where needed. This gives us the ability to handle faults in the context of active vision. Further, the distribution of software on the available hardware is such that users can utilize a dual-model of execution (simulation and rapid prototyping). Lastly, the tests we ran on the implemented architecture in order to validate the results of the experimentation and simulations show a good correlation of parameters.     

A Real-Time, Hierarchical, Sensor-Based Robotic System Architecture

A robotic system architecture is presented and its real-time performance, when used to control a robotic gripper system for deformation-free handling of limp material, is evaluated. A major problem to be overcome has been the integrability and compatibility issues between various components of the developed system. The software and hardware protocols and interfaces developed to control and coordinate the subsystem operations and interactions are presented. The performance of the developed real-time, hierarchical, sensor-based robotic system architecture is found to meet and satisfy a set of system operational constraints and demands as dictated by the industry.     

基于小波网络的机器人视觉伺服控制研究

本文基于小波神经网络设计了一种三关节机器人视觉伺服系统。该系统采用eye-in-hand方式,基于图像特征构成视觉反馈,来完成机器人抓取物体的任务。论文对系统结构、坐标变换、成像原理、视觉控制器进行了详细的设计,并通过仿真试验证明了所设计控制系统的有效性。     

A Neural Tactile Architecture Applied to Real-time Stiffness Estimation for a Large Scale of Robotic Grasping Systems

This paper presents a model for solving the problem of real-time neural estimation of stiffness characteristics for unknown objects. For that, an original neural architecture is proposed for a large scale robotic grasping systems applied for unknown object with unspecified stiffness characteristics. The force acquisition is based on tactile information from force sensors in robotic manipulator. The proposed model has been implemented on a robotic gripper with two parallel fingers and on a one d.o.f. robotic finger with opponent artificial muscles and angular displacements. This self-organized model is inspired of human biological system, and is carried out by means of Topographic Maps and Vector Associative Maps. Experimental results demonstrate the efficiency of this new approach.     

Decentralized autonomous control of a quadrupedal locomotion robot using oscillators

This article deals with the design of a control system for a quadrupedal locomotion robot. The proposed control system is composed of a leg motion controller and a gait pattern controller within a hierarchical architecture. The leg controller drives actuators at the joints of the legs using a high-gain local feedback control. It receives the command signal from the gait pattern controller. The gait pattern controller, on the other hand, involves nonlinear oscillators. These oscillators interact with each other through signals from the touch sensors located at the tips of the legs. Various gait patterns emerge through the mutual entrainment of these oscillators. As a result, the system walks stably in a wide velocity range by changing its gait patterns and limiting the increase in energy consumption of the actuators. The performance of the proposed control system is verified by numerical simulations. This work was presented in part at the Fifth International Symposium on Artificial Life and Robotics, Oita, Japan, January 26–28, 2000     

Development of micro-robot system for playing soccer games

This paper surveys recent trends in developing a micro-robot soccer system, and presents a design procedure for soccer-playing robots, focusing on our system based on the centralized approach. The robot soccer game has a lot of challenging problems, such as coordination between robots, motion planning of robots, visual recognition of objects, and so on. Considering the results of the MIROSOT contests, the centralized approach may be more powerful than the distributed approach in order to implement such functions. Our attempt was to develop a micro-robot system with a remote-brainless control architecture. After that, new techniques were applied to the chasis design, the actuators, the radio link, the vision system software, and the control strategy software. Using a fast vision system, we obtain the configuration of each robot, and then the host computer computes the desired motion and commands each robot directly via RF communication. We describe in detail some technical tips for developing the robots, and explain our strategy for obtaining the scores. This article also includes the most recent improvements in robot hardware and software. This work was presented, in part, at the Third International Symposium on Artificial Life and Robotics, Oita, Japan, January 19–21, 1998     

Precise Positioning of Binocular Eye-to-Hand Robotic Manipulators

This article addresses the visual servoing of a rigid robotic manipulator equipped with a binocular vision system in eye-to-hand configuration. The control goal is to move the robot end-effector to a visually determined target position precisely without knowing the precise camera model. Many vision-based robotic positioning systems have been successfully implemented and validated by supporting experimental results. Nevertheless, this research aims at providing stability analysis for a class of robotic set-point control systems employing image-based feedback laws. Specifically, by exploring epipolar geometry of the binocular vision system, a binocular visual constraint is found to assist in establishing stability property of the feedback system. Any three-degree-of-freedom positioning task, if satisfying appropriate conditions with the image-based encoding approach, can be encoded in such a way that the encoded error, when driven to zero, implies that the original task has been accomplished with precision. The corresponding image-based control law is proposed to drive the encoded error to zero. The overall closed-loop system is exponentially stable provided that the binocular model imprecision is small.     

机器人控制器核心设备的实时性研究

机器人控制器核心系统的实时性提高与改进是一个关键问题,结合机器人控制器的特点对操作系统平台的实时性进行分析,着重比较了Linux操作系统和改进的RTLinux实时操作系统在实时性上的区别,对机器人控制器任务采用多线程机制进行实时域和非实时域的重新划分,并提出一套实时性改造方案,完成机器人控制器的任务,最后给出了一个在RTLinux操作系统下实现硬件设备实时驱动程序的一个例子。     

Secure cooperation in a distributed robot system using active RFIDs

In this article, we develop a distributed robotic system that can provide various services in a real environment using ad-hoc networked active radio frequency identifications (RFIDs). These services are derived from a large amount of data acquired from sensors connected to active RFIDs. The primary advantage of this method is that it facilitates the construction of a real-environment monitoring system. Furthermore, a human's status and position can easily be identified by fitting active RFIDs to subjects. However, a security system is required for a radio ad-hoc network and a cooperation system between active RFIDs. In our research, we developed a multirobot cooperating system as a multiagent system and applied it to an active RFID, which has limited resources. We also developed a security system for active RFID communication that can be executed using limited resources. We then integrated the multiagent system and security system. We also constructed a robotic environment that can provide various services using active RFIDs and then evaluated it. This work was presented in part at the 10th International Symposium on Artificial Life and Robotics, Oita, Japan, February 4–6, 2005     

基于无线网络的云医疗机器人系统仿真

医疗机器人是一门集医学、仿生学、机械力学、材料学、计算机科学、运筹学、机器人学等学科于一体的新兴交叉学科。随着传感器技术、通信设备,尤其是云计算的发展,云医疗机器人应运而生。一个云医疗机器人只需要少量的硬件和软件配置,它所需的大部分资源和计算过程由连接的云端提供。云医疗机器人从计算或者资源配置密集型转化为效率和功能密集型,从而可以更高效地完成复杂任务。本文设计一种云医疗机器人系统平台,该平台由医疗云平台层和远程云机器人层组成。以系统平台为基础,利用无线网络技术设计2个云医疗机器人系统案例,并进行仿真。仿真结果表明,云医疗机器人系统具有效率高、成本低和应用性强等特点。     

Modelling and optimal controller design of networked control systems with multiple delays

In this paper we discuss the modelling and control of networked control systems (NCS) where sensors, actuators and controllers are distributed and interconnected by a common communication network. Multiple distributed communication delays as well as multiple inputs and multiple outputs (MIMO) are considered in the modelling algorithm. In addition, the asynchronous sampling mechanisms of distributed sensors are characterized to obtain the actual time delays between sensors and the controller. Due to the characteristics of a network architecture, piecewise constant plant inputs are assumed and discrete-time models of plant and controller dynamics are adopted to analyse the stability and performance of a closed-loop NCS. The analysis result is used to verify the stability and performance of an NCS without considering the impact of multiple time delays in the controller design. In addition, the proposed NCS model is used as a foundation for optimal controller design. The proposed control algorithm utilizes the information of delayed signals and improves the control performance of a control system encountering distributed communication delays. Several simulation studies are provided to verify the control performance of the proposed controller design.     

Closed-Loop Control of Robotic Arc Welding System with Full-penetration Monitoring

The real-time detection of the state of the gap and weld penetration control are two fundamental issues in robotic arc welding. However, traditional robotic arc welding lacks external information feedback and the function of real-time adjusting. The objective of this research is to adopt new sensing techniques and artificial intelligence to ensure the stability of the welding process through controlling penetration depth and weld pool geometry. A novel arc welding robot system including function modules (visual modules, data acquisition modules) and corresponding software system was developed. Thus, the autonomy and intelligence of the arc welding robot system is realized. Aimed at solving welding penetration depth, a neural network (NN) model is developed to calculate the full penetration state, which is specified by the back-side bead width (Wb), from the top-side vision sensing technique. And then, a versatile algorithm developed to provide robust real-time processing of images for use with a vision-based computer control system is discussed. To this end, the peak current self adaptive regulating controller with weld gap compensation was designed in the robotic arc welding control system. Using this closed-loop control experiments have been conducted to verify the effectiveness of the proposed control system for the robotic arc welding process. The results show that the standard error of the Wb is 0.124 regardless of the variations in the state of the gap.     

Evaluation of the Unified Model of the Sphere for Fisheye Cameras in Robotic Applications

Abstract

A wide field of view is required for many robotic vision tasks. Such an aperture may be acquired by a fisheye camera, which provides a full image compared to catadioptric visual sensors, and does not increase the size and the weakness of the imaging system with respect to perspective cameras. While a unified model exists for all central catadioptric systems, many different models, approximating the radial distortions, exist for fisheye cameras. It is shown in this paper that the unified projection model proposed for central catadioptric cameras is also valid for fisheye cameras in the context of robotic applications. This model consists of a projection onto a virtual unitary sphere followed by a perspective projection onto an image plane. This model is shown equivalent to almost all the fisheye models. Calibration with four cameras and partial Euclidean reconstruction are done using this model, and lead to persuasive results. Finally, an application to a mobile robot navigation task is proposed and correctly executed along a 200-m trajectory.     

A concept of dynamically reconfigurable real-time vision system for autonomous mobile robotics

This paper describes specific constraints of vision systems that are dedicated to be embedded in mobile robots. If PC-based hardware architecture is convenient in this field because of its versatility, flexibility, performance, and cost, current real-time operating systems are not completely adapted to long processing with varying duration, and it is often necessary to oversize the system to guarantee fail-safe functioning. Also, interactions with other robotic tasks having more priority are difficult to handle. To answer this problem, we have developed a dynamically reconfigurable vision processing system, based on the innovative features of Cleopatre real-time applicative layer concerning scheduling and fault tolerance. This framework allows to define emergency and optional tasks to ensure a minimal quality of service for the other subsystems of the robot, while allowing to adapt dynamically vision processing chain to an exceptional overlasting vision process or processor overload. Thus, it allows a better cohabitation of several subsystems in a single hardware, and to develop less expensive but safe systems, as they will be designed for the regular case and not rare exceptional ones. Finally, it brings a new way to think and develop vision systems, with pairs of complementary operators.     

Dynamic Analysis and Distributed Control of the Tetrobot Modular Reconfigurable Robotic System

Reconfigurable robotic systems can be adapted to different tasks or environments by reorganizing their mechanical configurations. Such systems have many redundant degrees of freedom in order to meet the combined demands of strength, rigidity, workspace kinematics, reconfigurability, and fault tolerance. In order to implement these new generations of robotic system, new approaches must be considered for design, analysis, and control. This paper presents an efficient distributed computational scheme which computes the kinematics, dynamics, redundancy resolution, and control inputs for real-time application to the control of the Tetrobot modular reconfigurable robots. The entire system is decomposed into subsystems based on a modular approach and Newton's equations of motion are derived and implemented using a recursive propagation algorithm. Two different dynamic resolution of redundancy schemes, the centralized Jacobian method and the distributed virtual force method, are proposed to optimize the actuating forces. Finally, distributed dynamic control algorithms provide an efficient modular implementation of the control architecture for a large family of configurations.     

Cooperation Protocols in Multi-Agent Robotic Systems

Multi-agent robotic systems are useful in many practical applications. For some tasks, such as holding a conference, cooperation among agents are necessary. For other tasks, such as cleaning a room, multiple agents can work in parallel for better performance. This paper provides help-based (HCP) and coordination-based (CCP) protocols for controlling agents to accomplish multi-agent tasks. The HCP utilizes efficient negotiation to coordinate agents into groups. The CCP improves overall performance by exchanging local knowledge among agents and making decisions in parallel. A reactive and modularized agent architecture was employed to implement the protocols. Since each protocol is embedded into the architecture, it is efficient and effective. In addition, the protocols are deadlock-free. The protocols were utilized to solve the Object-Sorting Task, which abstracts two characteristics of tasks: parallelism and cooperation. The experimental results showed that 1) both HCP and CCP are stable under different workload; 2) the protocols can effectively utilize the agent-power to achieve super-linear improvement; 3) The CCP is better than the HCP in both performance and speedup.