A bayesian approach to real-time obstacle avoidance for a mobile robot

Real-time obstacle avoidance is essential for the safe operation of mobile robots in a dynamically changing environment. This paper investigates how an industrial mobile robot can respond to unexpected static obstacles while following a path planned by a global path planner. The obstacle avoidance problem is formulated using decision theory to determine an optimal response based on inaccurate sensor data. The optimal decision rule minimises the Bayes risk by trading between a sidestep maneuver and backtracking to follow an alternative path. Real-time implementation is emphasised here as part of a framework for real world applications. It has been successfully implemented both in simulation and in reality using a mobile robot.     

两轮自平衡机器人控制系统的设计

针对自行设计的两轮自平衡机器人Opyanbot建立了动力学模型,应用最优控制和两轮差动等控制方法设计了控制器,提出了针对两轮自平衡机器人平衡和行进的新策略。为了提高两轮自平衡机器人的控制效果,利用基于DSP数字电路的全数字智能伺服驱动单元IPM100分别精确控制左右轮电机,并利用上位机实时控制机器人的运动状态,提高了控制精度、可靠度和集成度,得到了很好的控制效果。     

Disturbance management design for a holonic multiagent manufacturing system by using hybrid approach

This paper proposes a disturbance management methodology for an agent-based holonic manufacturing system by using hybrid control approach, with its application to a mobile manipulator system. Firstly, the architectures based on holarchy and agents are given. Then the framework of hybrid control strategy is outlined and the stability analysis for the closed-loop system is introduced. The major contribution of this work is the exploration for using hybrid control approach into disturbance management mechanism. The switched disturbance detector is presented and the identification algorithm is given. The hybrid controller is designed to reject the disturbance by switching between reactions against diagnosed symptoms. Finally, the case study onto the mobile manipulator hybrid system verifies the effectiveness and applicability of this design method. It validates the agility, efficiency, and retaining stability to system of the holonic multiagent concept for industrial or other application systems.     

Parkinson's disease: a motor control study using a wrist robot

Deep brain stimulation (DBS) is the most common surgical procedure for patients with Parkinson's disease (PD). DBS has been shown to have a positive effect on PD symptoms; however, its specific effects on motor control are not yet understood. We introduce the novel use of a wrist robot in studying the effects of stimulation on motor performance and learning. We present results from patients performing reaching movements in a null field and in a force field with and without stimulation. We discuss special cases where robotic testing reveals otherwise undiagnosed impairments, and where clinical scores and robot-based scores display opposing trends.     

Control system design of a 3-DOF upper limbs rehabilitation robot

This paper presents the control system design of a rehabilitation and training robot for the upper limbs. Based on a hierarchical structure, this control system allows the execution of sequence of switching control laws (position, force, impedance and force/impedance) corresponding to the required training configuration. A model-based nonlinear controller is used to impose the desired environment to the patient's arm. The knowledge of robot kinematics and dynamics is thus necessary to ensure haptic transparency and patient safety. The identification process of robot dynamics is emphasised and experimental identification results are given for the designed robot. The paper also presents a particular rehabilitation mode named Active-Assisted. Simulation results of this rehabilitation mode illustrate the potentialities of the overall control scheme, which can also be applied to other rehabilitation robots.     

TT-BIP: using correct-by-design BIP approach for modelling real-time system with time-triggered paradigm

In order to combine advantages of real-time operating systems implementing the time-triggered (TT) execution model and model-based design frameworks, we aim at proposing a correct-by-design methodology that derives correct TT implementations from high-level models. This methodology consists of two main steps: (1) transforming the high-level model into an intermediate model which respects the TT communication principles and where all communications between components are simple send/receive interactions, and (2) transforming the obtained intermediate model into the programming language of the target platform. In this paper, we focus on the presentation of the transformational methodology of the first step of this design flow. This methodology produces a correct-by-construction TT model by starting from a high-level model of the application software in behaviour, interaction, priority (BIP). BIP is a component-based framework with formal semantics that rely on multiparty interactions for synchronizing components. Commonly in TT implementations, tasks interact with each other through a communication medium. Our methodology transforms, depending on a user-defined task mapping, high-level BIP models where communication between components is strongly synchronized, into TT model that integrates a communication medium. Thus, only inter-task communications and components participating in such interactions are concerned by the transformation process. We also provide correctness proofs of the transformation and apply it on an industrial case study.     

Control system for the Khepera robot by a neural network with competition and cooperation

This article describes a new approach to control systems for a mobile robot Khepera by using a neural network with competition and cooperation as the processing unit for the robot sensors. Competition makes only one neuron active, while cooperation keeps them all active. In our research, we find that the Khepera controlled by this neural network can maintain a smoother trajectory than when it is controlled by the output values of its own sensors, especially in noisy environments. This work was presented in part at the Fifth International Symposium on Artificial Life and Robotics, Oita, Japan, January 26–28, 2000     

A holdsite method for parts acquisition using a laser rangefinder mounted on a robot wrist

Parts acquisition by a robot is an important industrial problem. Our method makes possible the acquisition of various types of parts which are jumbled together in a pile. An intensity image along with selected range data is used to guide a robot to a location, called a holdsite, at which it can grasp a part. The intensity image gives a rough indication of an area of interest and a laser rangefinder mounted on the robot wrist collects range data in its vicinity. This data is processed using spatial planning methods to find a good holdsite according to safety and stability criteria. The robot is then directed to the holdsite and the part is grasped. The algorithms are simple, fast, and have been successfully tested on a variety of parts.     

Control design for human-like reaching movements using redundancy in robot arm-trunk systems

This paper develops a control algorithm to show the human-like reaching movements in humanoid redundant systems involving the trunk. This algorithm neither requires the computation of pseudo-inverse of Jacobian nor does it need the optimization of any artificial performance index. The control law accommodates the time-varying temporal properties of the muscle stiffness and damping as well as low-pass filter characteristics of human muscles. It uses a time-varying damping shaping matrix and a bijective joint muscle mapping function to describe the spatial characteristics of human reaching motion like quasi-straight line trajectory of the end-effector and symmetric bell shaped velocity profile as well as the temporal characteristics like the occurrence of the peak velocity of the trunk motion after the peak velocity of the arm motion. The aspect of self-motion is also analyzed using the null-space motion of the manipulator Jacobian. The effects of the control parameters on the motion pattern are analyzed in detail and some basic guidelines have been provided to select their proper values. Simulation results show the efficacy of the newly developed algorithm in describing humanmotion characteristics.     

A design approach for ultrareliable real-time systems

A design approach developed over the past few years to formalize redundancy management and validation is described. Redundant elements are partitioned into individual fault-containment regions (FCRs). An FCR is a collection of components that operates correctly regardless of any arbitrary logical or electrical fault outside the region. Conversely, a fault in an FCR cannot cause hardware outside the region to fail. The outputs of all channels are required to agree bit-for-bit under no-fault conditions (exact bitwise consensus). Synchronization, input agreement, and input validity conditions are discussed. The Advanced Information Processing System (AIPS), which is a fault-tolerant distributed architecture based on this approach, is described. A brief overview of recent applications of these systems and current research is presented     

Control system design for mechanical systems using contractiontheory

Contraction theory is a control system tool based on an exact differential analysis of convergence. After establishing new combination properties of contracting systems, the paper derives new controller and observer designs for mechanical systems such as aircraft and underwater vehicles. The classical nonlinear strap down algorithm is also shown to be marginally contracting. The relative simplicity of the approach stems from its effective exploitation of the systems' structural specificities     

Sensory interactive robot trajectory control using a real-time world model

A major consideration in the design of sensory interactive trajectory generation software for a Flight Telerobotic Servicer (FTS) is the availability and maintenance of a current model of the manipulator's world. The NASA/NBS Standard Reference Model for Telerobot Control System Architecture (NASREM), which has been adopted by NASA for control of the FTS, provides a logical computing architecture for telerobotics. It defines a hierarchical control system in which complex tasks are decomposed into progressively simpler subtasks, or objectives. It contains a hierarchy of world modeling modules which maintain the system's internal model of the manipulator and its world by continuously updating the model based upon sensory data. Each world modeling module contains support processes or functions which simultaneously and asynchronously support sensory processing and task decomposition. This paper discusses the role of world modeling in support of trajectory generation and execution. For sensory interactive robot motion control, the world modeling modules must operate rapidly so that the model of the world remains in registration with the real world.This paper discusses the world modeling modules of a hierarchical control system which facilitate sensory interactive trajectories by decoupling and supporting the sensory and manipulator planning processes. We define the types of information which should be included in the interfaces to the modules, as well as the modules' structure and function. Finally, we discuss the real-time implementation and experimental results of a particular sensory interactive algorithm performed in our laboratory.     

Component-based robot system design for grasping tasks

The paper presents a robot system design with highly reusable components for a component-based robot system for manipulation tasks. The robot system is designed based on the analysis of manipulation tasks using a unified modeling language use case diagram. For a service robot with locomotion and manipulation mechanisms, reusability of robot system components is improved by adopting the proposed design. Our structure consists of scenario, task, robot information management server, data analyzer, sensor hardware controller, skill, and motion hardware controller on a component-based robot system. Based on the proposed robot system, we implemented a component-based robot system and subsequently realized a grasping motion by a service robot.     

使用补偿策略的机器人遥操作系统的控制研究

利用混杂动态系统的思想通过同时采用事件和时间驱动的执行器方案来弥补机器人遥操作系统中的不确定时延现象.即作为控制节点的操作者的控制决策发出时间是事件驱动的(满足一定条件下),执行器节点的接收也是事件驱动的,但是执行则是时间驱动的.通过这样的方法确保网络遥操作系统在每一采样周期内都能得到新的控制信号,从而补偿网络延迟.     

Towards a systematic approach to real-time sonification design for surface electromyography

Surface electromyography (sEMG) is a technique for measuring the electrical activity of muscles and is often used as a biofeedback tool. However, challenges associated with the typically visual display of sEMG data have motivated researchers to find non-visual ways of displaying sEMG data, and parameter-mapping sonification has been explored in order to present sEMG data acoustically. Parameter-mapping sonification is a technique that involves mapping values in a data set to acoustic properties of sound. Sonification of EMG data has shown potential for identifying musculoskeletal disease and improving athletic and exercise performance. However, many sonification designs to date have not been systematically evaluated and there have been few quantitative approaches to objective comparisons of sonification paradigms. In this study, we performed a quantitative comparison of different sonification designs in order to test our hypothesis that different sonification designs may be better suited to different tasks. Thirty-six participants (ages 18–31, 14 male) who volunteered to listen to the sEMG sonifications created for this study were asked to identify two different features of the data: muscle activation time and muscle exertion level. Their responses were analyzed in order to determine the effect of sonification design on listener performance. Results indicated that having the sonifications spatialized resulted in the best performance for both tasks. However, different sonification designs resulted in the best performance for the muscle activation time estimation task (Pitch and Loudness mapped redundantly) and the muscle exertion level estimation task (Pitch, Loudness, and Attack mapped redundantly). Further, for the time estimation task, the use of the Attack mapping appeared to reliably inhibit performance. These findings strongly suggest that sonification designs for sEMG need to be designed differently based on the task the user is performing.     

The design of a fuzzy system shell using a database approach

This study presented a prototype of fuzzy system shell called FuzzyAccess. Using Microsoft Access database as a developing tools, the proposed system provided a friendly interface for user self-building a fuzzy system. A novice who has no programming-knowledge can also self-define a new fuzzy project. The main contributions of the proposed system were that using SQL method to search the candidate rules in rule evaluation stage and providing an integrated tuning interface for system adjustment. The SQL method can significantly reduce the search time in rule evaluation. The integrated tuning interface can assist user quickly inspecting the influence among different system parameters adjustment and reducing the system development time.     

移动机器人实时目标跟踪系统设计与实现

针对单目视觉移动机器人目标跟踪的实时性和鲁棒性要求,提出了基于Kalman滤波器的改进Camshift算法检测和定位目标.将Kalman预测值作为目标初始位置,补偿摄像头和目标相对运动导致的目标在图像中的偏移.在系统“跟丢”后判断目标丢失的原因,根据原因自适应拓展搜索窗口作为Cam-shift算法的下一帧初始搜索窗口.为了验证改进算法的有效性,自主研制了一种应用该算法的履带式机器人实时目标跟踪系统.实验结果表明:该系统具有很好的鲁棒性和实时性.     

移动机器人无线实时反馈控制系统的设计

由于移动机器人左右两轮的非线性特征,其反馈调节无法克服这一特性,必须借助PC机来进行调节。为此提出了一种无线实时反馈控制方法,在PC机上加入PID控制算法,实现了对机器人的无线实时反馈控制。