Coordinating mobility and manipulation using nonholonomic mobile manipulators

This paper deals with coordinated tasks for mobile nonholonomic manipulators. The systems are composed of a nonholonomic mobile platform and a simple kinematic chain holonomic arm. First, concepts such as redundancy and singular configurations are defined. Then, reduced differential models are introduced. It is then possible to work with a set of independent task coordinates. Applications follow for a planar system in the case of point-to-point and continuous path tasks.     

Estimating text legibility of a mobile display on the basis of translational vibration caused by walking

Abstract— In this study, the effect of vibration on mobile‐phone text legibility caused by walking was examined. Legibility was measured as reading performance and subjective task load when reading from a mobile‐phone display while walking on a treadmill at 1.5 km/hour, 3 km/hour, and an individually defined speed (3.9 km/hour on average). Vibration was measured on the vertical, lateral, and fore‐and‐aft axes during walking. Vibration amplitude was calculated in five different frequency bands (1, 2, 4, 8, and 16 Hz), and correlated with the legibility measures. The amplitude increased most on the vertical and fore‐and‐aft axes as a function of walking speed, and the increase was largest in the 2‐Hz frequency band. Legibility decreased concurrently with increasing vibration. The strong correlation between vibration characteristics and legibility measures suggests that vibration characteristics could, to some degree, be used in estimating small‐display legibility while walking.     

Restock and straightening system for retail automation using compliant and mobile manipulation

As the retail industry keeps expanding and shortage of workers increasing, there is a need for autonomous manipulation of products to support retail operations. The increasing amount of products and customers in establishments such as convenience stores requires the automation of restocking, disposing and straightening of products. The manipulation of products needs to be time-efficient, avoid damaging products and beautify the display of products. In this paper, we propose a robotic system to restock shelves, dispose expired products, and straighten products in retail environments. The proposed mobile manipulator features a custom-made end effector with compact and compliant design to safely and effectively manipulate products in retail stores. Through experiments in a convenience store scenario, we verify the effectiveness of our system to restock, dispose and rearrange items.     

On-line parameter identification of a cart by mobile manipulation pushing

In this paper, a model identification method for unknown parameters of a non-holonomic cart has been developed. By interactions between a mobile manipulator and the cart, the sensory information is collected to estimate the model parameters of the cart. Since the raw data are contaminated by noise that cannot be modeled statistically, a wavelet based least square method (LSM) is proposed to estimate these parameters for the cart. The raw signal is decomposed into certain bandwidths to generate a series of new signals, which are used to estimate the parameters. The new signal, which has the minimal estimation residual in the least square sense, is adopted as the best estimation. The error convergence of the estimation approach is given. The experimental results indicate that the estimation accuracy can be significantly improved by the use of the proposed method.     

High-speed manipulation of information representations. i. normalization and mobile canonicalization

Information representations, IR, are linear representations of N-dimensional topological maps that can be used to describe virtually any abstract (e.g. the properties of a mathematical equation), static (e.g. chemical formulae, still pictures or fingerprints) or dynamic (e.g. flight paths of rockets or cloud chamber pictures) data. An IR can be manipulated to obtain mathematically equivalent forms that are either unique (normal) or alternative (canonical) representations. Here high-speed algorithms for obtaining normal and canonical forms of IRs are described and demonstrated.     

Efficient 3D object perception and grasp planning for mobile manipulation in domestic environments

In this article, we describe efficient methods for tackling everyday mobile manipulation tasks that require object pick-up. In order to achieve real-time performance in complex environments, we focus our approach on fast yet robust solutions. For 3D perception of objects on planar surfaces, we develop scene segmentation methods that process depth images in real-time at high frame rates. We efficiently plan feasible, collision-free grasps for the segmented objects directly from the perceived point clouds to achieve fast execution times. We evaluate our approaches quantitatively in lab experiments and also report on the successful integration of our methods in public demonstrations at RoboCup@Home competitions in 2011 and 2012.     

Precise and efficient pose estimation of stacked objects for mobile manipulation in industrial robotics challenges

Object manipulation tasks such as picking up, carrying and placing should be executed based on the information of objects which are provided by the perception system. A precise and efficient pose estimation system has been developed to address the requirements and to achieve the objectives for autonomous packaging, specifically picking up of stacked non-rigid objects. For fine pose estimation, a drawing pin shaped kernel and pinhole filtering methods are used on the roughly estimated pose of objects. The system has been applied in a realistic industrial environment as a challenging scenario for the Challenge 2 – Shop Floor Logistics and Manipulation on a mobile manipulator in the context of the European Robotics Challenges (EuRoC) project.     

Consideration of LCD legibility for automobiles

Some improvement is required in legibility of liquid crystal displays for them to be used in cars. Many factors - for example LCD material characteristics, cell gap, polarizers, operating conditions and instrument panels arrangements - influence the legibility. The dependence of contrast, viewing angle and response on such factors was investigated and a method of using LCDs for automobiles established.     

Text legibility and the letter superiority effect

Effects of font design and electronic display parameters upon text legibility were determined using a threshold size method. Participants' visual acuity (inverse of the minimum detection size, representing the threshold legibility for each condition) was measured using upper- and lowercase letters and lowercase words in combinations of 6 fonts, 3 font-smoothing modes, 4 font sizes, 10 pixel heights, and 4 stroke widths. Individual lowercase letters were 10% to 20% more legible than lowercase words (i.e., lowercase words must be 10%-20% larger to have the same threshold legibility). This letter superiority effect suggests that individual letters play a large role and word shape plays a smaller role, if any, in word identification at threshold. Pixel height, font, stroke width, and font smoothing had significant main effects on threshold legibility. Optimal legibility was attained at 9 pixels (10 points). Verdana and Arial were the most legible fonts; Times New Roman and Franklin were least legible. Subpixel rendering (ClearType) improved threshold legibility for some fonts and, in combination with Verdana, was the most legible condition. Increased stroke width (bold) improved threshold legibility but only at the thinnest width tested. Potential applications of this research include optimization of font design for legibility and readability.     

Generality in design and compositional verification usingTav

It is a well recognised fact that design errors in parallel systems are often hard to identify—due to their non-deterministic nature. It is therefore important that designs are analysedbefore the implementation phase begins. Even small parallel systems often have an intrinsic structure which is hard to fully understand, and the support of automated tools is therefore indispensable. In order to be of any practical use, the computations of such tools must be (polynomially) effective in terms of the system size, and furthermore it must be possible to reason about the system in terms of the properties of its (parallel) components—in order to avoid state-space explosion. Finally, the well-establishedstepwise refinement design strategy must be supported.The tools of theTav-system fulfil the above requirements, and in this paper we present its features by analysing a simple transmission protocol. The cornerstone of the system is the theory ofmodal transition systems, which allows for efficient decidability, stepwise refinement, and compositionality. The theory also supports a unique feature ofTav, namely the ability to provide explanations in case of design errors.This work has been supported in part by the POTP-project at Aalborg University and by the Esprit project Concur 2.     

移动双臂机械手系统协调操作的视觉伺服技术

本文利用双目泛倾斜变焦摄像机(pan-tilt-zoom,PTZ)像机,实现移动双臂机械手系统的视觉伺服协调操作,重点研究室内复杂环境和光照变化情况下目标物体的检测、识别和定位问题.首先,提出了色调、饱和度、亮度颜色模型(hue-saturation-value,HSV)空间下图像分割的改进算法,通过阈值更新和外接矩形改善分割结果,提高检测算法对环境光照变化的适应性;然后,基于Hu不变矩,利用物体形状特征,对检测得到的物体加以识别:在此基础上,利用摄像机投影矩阵,计算目标物体的空间坐标,实现其定位测量:最后,在实验室平台上,通过模拟双臂倒水操作,验证提出的图像处理和分析算法以及视觉伺服协调操作方案的有效性.实验结果表明移动双臂机械手系统能够成功完成倒水动作的协调操作.     

Rectification of legibility distance in a driving simulator

Visual differences lead to differences in the legibility distances of traffic signs between driving simulators and real road environments. To ensure that the legibility distance in a simulator is similar to that in the real world, this study proposes a theoretical equation for predicting legibility distance and a simple algorithm for determining the magnifying power of a traffic sign for a display system in a simulator. Experiments of traffic sign recognition using a simulator were conducted under quasi-static and dynamic driving conditions. On-road tests were also carried out under quasi-static and dynamic driving conditions. Thirty healthy and non-disabled volunteers were recruited. The experimental results showed that the proposed theoretical equation for predicting legibility distance and the simple algorithm for determining the magnifying power of traffic signs reduced the difference in legibility distances between the simulator and real road environment under quasi-static and dynamic driving conditions.     

Exploring legibility of augmented reality X-ray

Virtual objects can be visualized inside real objects using augmented reality (AR). This visualization is called AR X-ray because it gives the impression of seeing through the real object. In standard AR, virtual information is overlaid on top of the real world. To position a virtual object inside an object, AR X-ray requires partially occluding the virtual object with visually important regions of the real object. In effect, the virtual object becomes less legible compared to when it is completely unoccluded. Legibility is an important consideration for various applications of AR X-ray. In this research, we explored legibility in two implementations of AR X-ray, namely, edge-based and saliency-based. In our first experiment, we explored on the tolerable amounts of occlusion to comfortably distinguish small virtual objects. In our second experiment, we compared edge-based and saliency-based AR X-ray methods when visualizing virtual objects inside various real objects. Moreover, we benchmarked the legibility of these two methods against alpha blending. From our experiments, we observed that users have varied preferences for proper amounts of occlusion cues for both methods. The partial occlusions generated by the edge-based and saliency-based methods need to be adjusted depending on the lighting condition and the texture complexity of the occluding object. In most cases, users identify objects faster with saliency-based AR X-ray than with edge-based AR X-ray. Insights from this research can be directly applied to the development of AR X-ray applications.     

Lighting characteristics, legibility and visual comfort of displays

In future, as well as visual human-computer interfaces, acoustic interfaces will get more and more important. However, the visual channel will be the more important channel due to its capacity. Therefore, it is necessary not only to optimize the display with regard to performance and time, but also to acceptance and subjective workload. On the one hand the single character (luminance, geometry, shape, colour) and on the other hand the arrangement of characters (distance of characters, image distortions, structure of text) should be adapted to human psychophysiological abilities. Moreover, the influence of the environment (lighting) and time-dependent phenomena (flicker, jitter) should be taken into consideration. Good ergonomics should imply the use of all possibilities which the flexible new technology offers for workplaces, including sensory or muscularly handicapped people.     

Lighting characteristics,legibility and visual comfort of displays

Abstract

In future, as well as visual human-computer interfaces, acoustic interfaces will get more and more important. However, the visual channel will be the more important channel due to its capacity. Therefore, it is necessary not only to optimize the display with regard to performance and time, but also to acceptance and subjective workload. On the one hand the single character (luminance, geometry, shape, colour) and on the other hand the arrangement of characters (distance of characters, image distortions, structure of text) should be adapted to human psychophysiological abilities. Moreover, the influence of the environment (lighting) and time-dependent phenomena (flicker, jitter) should be taken into consideration. Good ergonomics should imply the use of all possibilities which the flexible new technology offers for workplaces, including sensory or muscularly handicapped people.     

Design and manufacturing of mobile micro manipulation system with a compliant piezoelectric actuator based micro gripper

This paper presents a new design of mobile micro manipulation system for robotic micro assembly where a compliant piezoelectric actuator based micro gripper is designed for handling the miniature parts and compensation of misalignment during peg-in-hole assembly is done because piezoelectric actuator has capability of producing the displacement in micron range and generates high force instantaneously. This adjusts the misalignment of peg during robotic micro assembly. The throughput/speed of mobile micro manipulation system is found for picking and placing the peg from one hole to next hole position. An analysis of piezoelectric actuator based micro gripper has been carried out where voltage is controlled through a proportional-derivative (PD) controller. By developing a prototype, it is demonstrated that compliant piezoelectric actuator based micro gripper is capable of handling the peg-in-hole assembly task in a mobile micro manipulation system.     

ATE通用性设计与实现

为使ATE具有通用性，首先介绍了ATE的组成，对实现其通用性的问题进行了分析，重点讨论了设计过程中应遵循的原则和方法，并在实际系统设计时进行了运用，使系统的通用性得到了提高。