Development of a dual-robot system for prototype production

A dual-robot machining system has been developed for manufacturing complex objects. The system consists of two six-axis industrial robots with flexible tool changers, a CAD/CAM package for geometric design and toolpath generation, a robot simulation package for collision avoidance, and a vision system for robot calibration. It offers the flexibility to reconfigure the robots of the system to accommodate workpieces of different shapes and sizes. A prototype of the system has been successfully developed and tested, and shows satisfactory performance in machining quality and control over the configurations of the robots. Examples are given of the application of the system to machining objects with spherical and sculptured surfaces. The system has been shown to be flexible, reconfigurable, automatic, and capable of manufacturing complex prototypes in the current industry environment.     

Development and pilot testing for virtual manufacturing tools with intelligent attributes

The use of synthetic and surrogate tools in training robots and planning events within virtual environments has tremendous potential in making the programming of complex machines simple and easy. For example, by designating tasks off-line with the virtual tools, attributes such as process planning and collision avoidance can be automatically and efficiently incorporated. In our research we have experimented with the use of attribute laden virtual tools in various tasks such as robotic-based grinding and welding processes. Such attribute laden virtual tools aid human operators in path planning as well as in making decisions about the process itself. In this paper we have tested our concepts of virtual tools and the use of attributes such as physical, reflex and command actions. Four sets of experiments were conducted with human subjects. Two kinds of virtual tools were used in these experiments, one with guide plane attributes and the other without them. One set of experiments using the head mounted display interface, tested human performance and evaluated the effect of the learning process in using the virtual tools. Results showed that there was marked improvement in task execution time using the tools laden with guide plane attributes over the unencumbered virtual tools. This paper discusses various future applications of these virtual tools in manufacturing. It is observed that unlike non-haptic visual interfaces, where no physical feed back is available to the user, attribute laden tools could provide a much easier interface to robots.     

Pedestrian-behavior-based mobile agent control in intelligent space

This paper investigates a human walking behavior-based mobile robot control system. The Intelligent Space (iSpace) is a distributed sensory system, which is the background infrastructure to observe human walking in a limited area. The observation of human walking behavior is applied to train fuzzy-neural networks (FNN). The trained FNNs are applied to approximate the obstacle avoidance behavior of human walking. The paper introduces the iSpace and the mobile agents, which are mobile robots, utilizing the intelligence of the iSpace. The observed and trained human walking behaviors are applied to control the mobile agent in a human-robot shared environment. Experimental results demonstrate the effectiveness of the FNN-based control system.     

Obstacle detection and avoidance with noisy measurements using danger zone concepts

Potential collision danger increases if a vehicle gradually moves closer to other vehicles or obstacles. If the collision time can be predicted before the vehicle is dangerously close to other vehicles or obstacles, the vehicle can devise an effective evasive maneuver or reroute its path, thus avoiding collision. This paper proposes an obstacle avoidance algorithm for unmanned vehicles in an unknown environment. The proposed avoidance algorithm uses the danger zone concept to determine whether the obstacle or surrounding vehicle will cause a possible collision. The danger zone is constructed around the vehicle by using semi-algebraic functions. The possible collision can be predicted by checking the sign of these semi-algebraic functions. The semi-algebraic functions for constructing the danger zone apply the relative velocities between the vehicle, and other vehicles or obstacles and can be used for both two- and three-dimensional cases. Several avoidance schemes are provided, with examples to demonstrate the concept of the proposed approach.     

受限柔性机器人的模型降阶及变结构力／位置控制

研究了具有柔性前臂的两连杆柔性机器人的混合力／位置控制问题。首先，利用奇异值分解法对所给出的受限柔性机器人模型进行分解，再利用伪逆的概念引入一个新的降阶坐标使各子系统降价，并分别对各子系统进行力控制器和位置控制器的设计。为了获得对拟静态假设的鲁棒补偿，对位置控制器采用变结构控制并进行了理论论明。最后，通过仿真进一步验证了本方案高精度性和强鲁棒性。     

Conceptual robustness in simultaneous engineering: A formulation in continuous spaces

This paper develops a robust and distributed decision-making procedure for mathematically modeling and computationally supporting simultaneous decision-making by members of an engineering team. The procedure (1) treats variations in the design posed by other members of the design team asconceptual noise; (2) incorporates such noise factors into conceptually robust decision-making; (3) provides preference information to other team members on the variables they control; and (4) determines whether to execute the conceptually robust decision or to wait for further design certainty. While Changet al. (1994) extended Taguchi's approach to such simultaneous decision-making, this paper uses a continuous formulation and discusses the foundations of the procedure in greater detail. The method is demonstrated by a simple distributed design process for a DC motor, and the results are compared with those obtained for the same problem using sequential decision strategies in Krishnanet al. (1991).     

Collision avoidance timing analysis of DSRC-based vehicles

Dedicated short-range communication (DSRC) has been used in prototyped vehicles to test vehicle-to-vehicle communication for collision avoidance. However, there is little study on how collision avoidance software should behave to best mitigate accident collisions. In this paper, we analyse the timing of events and how they influence software-based collision avoidance strategies. We have found that the warning strategies for collision avoidance are constrained by the timing of events such as DSRC communication latency, detection range, road condition, driver reaction and deceleration rate. With these events, we define two collision avoidance timings: critical time to avoid collision and preferred time to avoid collision, and they dictate the design of software-based collision avoidance systems.     

Vision-based sensing and control for space robotics applications

The following problems arise in the precise positioning of payloads by space manipulators: (1) the precise measurement of the relative position and motion of objects in the workspace of the robot; (2) the design of a control system, which is robust and performs well in spite of the effects of structural flexibility and oscillations typically associated with space robots. This paper discusses the solution to the measurement problem by a vision system using photogrammatic image processing to determine the motion of objects in real time. Performance characteristics are presented. The control problem is addressed by a new technique dealing effectively with the challenge posed by the noncollocated sensor/actuator configuration on the flexible robot structure. The laboratory implementation of the measurement and control concepts is discussed. Preliminary results validate the concepts     

虚拟生产环境中的实时碰撞检验技术

针对由机床、机器人等成百上千个物体构成的虚拟生产环境澡的实时碰撞检验问题，提出了一个由数据结构支持的层次化紧符合碰撞检验算法，解决了含凹多面体的、复杂障碍空间中多移动物体的碰撞检验问题，算法能够自动报告将要发生和已经发生的几何接触，并精确检测出两个移动物体的最小欧氏空间距离和最大干涉量，它们是计算干涉力和机器人运动规划中罚函数的重要参数，算法能够快速收敛且鲁棒性好。     

虚拟制造中多机器人虚拟生产平台的研究

以多机器人装配作业为背景,研究了虚拟制造中多机器人虚拟生产平台系统的几何及运动学建模,多机器人协调合作策略,多机器人工作空间分配,机器人手臂的碰撞检验和避碰以及装配线意外故障的处理等关键问题,最络构建起一个完整的多机器人虚拟生产平台。     

基于遇障速度法足球机器人的路径规划

提出了机器人在动态环境下的路径规划方法。这种方法基于机器人运动速度信息制定的避障策略。通过遇障速度的几何变换产生可达避障速度，从而确定运动路径上潜在的障碍物。同时，还推导了机器人路径搜索树网格算法。足球机器人仿真比赛表明，这种方法适用于动态和静态障碍物的避障。     

Oscillators and crank turning: exploiting natural dynamics with a humanoid robot arm

This paper presents an approach to robot-arm control that exploits the natural dynamics of the arm. This is in contrast to traditional approaches, which either ignore or cancel out arm dynamics. While the traditional approaches are more general, they often result in systems and robot designs that are not robust. The alternative approach gives systems that are computationally simple, robust to variation in system parameters, robust to changes in the dynamics themselves, and versatile. The approach is examined using the example of a compliant robot arm, controlled by independent neural oscillators, in a crank-turning task. A model is constructed, and the robot behaviour compared with the model. These data show that the arm-oscillator system is exploiting the natural dynamics by finding and exciting the resonant mode of the underlying mechanical system. Since this is a natural behaviour of the system, the robot behaviour is robust. The paper concludes by discussing the opportunities and limitations of this approach.     

Fatigue control of thin‐walled structures

The control of the ultimate fatigue behaviour of slender thin‐walled structures is treated in the paper. A macro‐ and micromechanical simulation model adopting the neural network approach is used for the numerical analysis of the problem. The numerical treatment of the non‐linear problems is made using the updated Lagrangian formulation of motion combined with the pseudo‐force technique in the FETM‐approach. Each step of the iteration approaches the solution of the linear problem and the feasibility of the parallel processing and neural network numerical techniques is established. The application on the actual slender bridge is made in order to demonstrate the efficiency of the procedures suggested. Copyright © 2003 John Wiley & Sons, Ltd.     

Optimization of washing machine kinematics,dynamics, and stability during spinning using a multistep approach

The vibrations originating from badly distributed load inside the drum are in this paper channeled into cost functions which are used as objectives for optimization. The defined kinematic cost function deals with performance of tub motion and can ensure margins to collision of parts inside the washing machine or constitute a step in the process to increase the machine capacity. The dynamic cost function measures transmitted vertical force to the hosting structure. Forces which cause noise and vibration impact on the surroundings. Two different cost functions for stability of a washing machine in the sense of walking avoidance are also presented. The difference between these formulations is studied with an example, which shows that although it is costly to evaluate the second formulation it will give more freedom to find good washing machine designs. Three different applied problems which aim to optimize different suspension designs for new and existing washing machines are presented. For effective numerical computation of the complex multiobjective optimization problems a multistep approach for washing machine structural optimization is presented. With the help of parallel calculation of the response of dynamic models implemented in Adams?View, the approach has been used to solve the presented problems. Results derived from the solution to the optimization problems have been used in development of new washing machines which afterwards have been put on the market.     

A rear-end collision risk assessment model based on drivers’ collision avoidance process under influences of cell phone use and gender—A driving simulator based study

Driver’s collision avoidance performance has a direct link to the collision risk and crash severity. Previous studies demonstrated that the distracted driving, such as using a cell phone while driving, disrupted the driver’s performance on road. This study aimed to investigate the manner and extent to which cell phone use and driver’s gender affected driving performance and collision risk in a rear-end collision avoidance process. Forty-two licensed drivers completed the driving simulation experiment in three phone use conditions: no phone use, hands-free, and hand-held, in which the drivers drove in a car-following situation with potential rear-end collision risks caused by the leading vehicle’s sudden deceleration. Based on the experiment data, a rear-end collision risk assessment model was developed to assess the influence of cell phone use and driver’s gender. The cell phone use and driver’s gender were found to be significant factors that affected the braking performances in the rear-end collision avoidance process, including the brake reaction time, the deceleration adjusting time and the maximum deceleration rate. The minimum headway distance between the leading vehicle and the simulator during the rear-end collision avoidance process was the final output variable, which could be used to measure the rear-end collision risk and judge whether a collision occurred. The results showed that although cell phone use drivers took some compensatory behaviors in the collision avoidance process to reduce the mental workload, the collision risk in cell phone use conditions was still higher than that without the phone use. More importantly, the results proved that the hands-free condition did not eliminate the safety problem associated with distracted driving because it impaired the driving performance in the same way as much as the use of hand-held phones. In addition, the gender effect indicated that although female drivers had longer reaction time than male drivers in critical situation, they were more quickly in braking with larger maximum deceleration rate, and they tended to keep a larger safety margin with the leading vehicle compared to male drivers. The findings shed some light on the further development of advanced collision avoidance technologies and the targeted intervention strategies about cell phone use while driving.     

非确定因素下汽车半主动悬架的智能控制

以含磁流变阻尼器的1/4 车辆非线性半主动悬架模型为研究对象,在充分考虑该非线性系统未建模动态的基础上提出了具体的神经网络与滑模变结构控制相结合的智能控制策略,有效抑制了悬架系统的振动,使车辆行驶的平顺性与舒适性得以提高.应用神经网络的在线学习能力对非线性动力学模型的不确定部分及外界未知扰动进行了神经网络估计,确定了未知函数的上确界,构造了控制系统的滑模变量并且合理设计神经网络的自适应规律使状态变量快速接近原点.通过稳定性分析证明了此种控制方法是全局渐近收敛的,并且对未建模动态具有强鲁棒性.数值仿真结果验证了该种控制方法的有效性,得到了阻尼器两端控制电压的变化规律.     

A swept volume approach based on hermite interpolation for optimization in collision‐free motion planning

Abstract

The recursive quadratic programming (RQP) technique has been successfully applied for the motion planning problem. This paper inherits the RQP optimization formulation to solve collision‐free motion planning problems. The focus of the paper is to develop a more accurate approach to represent the swept volume based on Hermite interpolation. The non‐convex swept volume may be described by parametric representation. Based on this idea, the non‐convex limitation of the motion planning by the previous RQP technique can be overcome and it has yielded accurate answers in distance calculation. Also, have been presented to illustrate and demonstrate this approach in the paper.     

Bioinspired Electronics for Artificial Sensory Systems

Humans have a myriad of sensory receptors in different sense organs that form the five traditionally recognized senses of sight, hearing, smell, taste, and touch. These receptors detect diverse stimuli originating from the world and turn them into brain‐interpretable electrical impulses for sensory cognitive processing, enabling us to communicate and socialize. Developments in biologically inspired electronics have led to the demonstration of a wide range of electronic sensors in all five traditional categories, with the potential to impact a broad spectrum of applications. Here, recent advances in bioinspired electronics that can function as potential artificial sensory systems, including prosthesis and humanoid robots are reviewed. The mechanisms and demonstrations in mimicking biological sensory systems are individually discussed and the remaining future challenges that must be solved for their versatile use are analyzed. Recent progress in bioinspired electronic sensors shows that the five traditional senses are successfully mimicked using novel electronic components and the performance regarding sensitivity, selectivity, and accuracy have improved to levels that outperform human sensory organs. Finally, neural interfacing techniques for connecting artificial sensors to the brain are discussed.     

Optimization in simulations of human movement planning

This paper discusses optimization algorithms in movement simulations for models of humans, humanoid robots or other mechanisms. Targeted movements between two configurations define a dynamically redundant system, for which there is freedom in the choice of control force time variations. A previously developed formulation for the treatment of targeted dynamics for mechanisms was used as a basis. The paper describes the development of an algorithm related to the method of moving asymptotes for the necessary optimization. The algorithm is specifically adapted to problems which are large and non‐linear but sparse, and which include very high numbers of design variables as well as constraints. In particular, non‐linear equality constraints from dynamic equilibrium equations are important. The optimization algorithm was developed to include these, but also in order to allow successively increasing penalty factors for constraint violations. The resulting setting was shown to be able to handle the systems established, robustly giving convergence to at least a local minimum also for very distant start iterates. The existence of very closely situated local optima, representing very similar movements, was discovered for the problem formulation, calling for an ad hoc method for finding the best of these local optima. Copyright © 2011 John Wiley & Sons, Ltd.