A compliant self-adaptive gripper with proprioceptive haptic feedback

Grippers and robotic hands are an important field in robotics. Recently, the combination of grasping devices and haptic feedback has been a promising avenue for many applications such as laparoscopic surgery and spatial telemanipulation. This paper presents the work behind a new self-adaptive, a.k.a. underactuated, gripper with a proprioceptive haptic feedback in which the apparent stiffness of the gripper as seen by its actuator is used to estimate contact location. This system combines many technologies and concepts in an integrated mechatronic tool. Among them, underactuated grasping, haptic feedback, compliant joints and a differential seesaw mechanism are used. Following a theoretical modeling of the gripper based on the virtual work principle, the authors present numerical data used to validate this model. Then, a presentation of the practical prototype is given, discussing the sensors, controllers, and mechanical architecture. Finally, the control law and the experimental validation of the haptic feedback are presented.     

Haptic function evaluation of multi-material part design

Recently haptic shape modeling has got a momentum in industrial and conceptual design. In this paper, a real-time haptic interface of synthesized shape modeling and haptic function evaluation of product design for multi-material part is presented. Due to the advancement of manufacturing technologies, multi-material is increasingly employed by industrial designers as a means for increasing the appeals of a product while also adding functional capability. Multi-material part manufacturing processes allow designers to select different materials for different portions of a product in order to improve the material-function compatibility for the overall product. For quick design verification, the shape design and function evaluation are implemented in the same haptic environment where a load can be applied to a part design using a haptic device and at the same time the combined reaction of the part in terms of displacement and reaction can be visualized and felt by the user. The intuitive correlation between the applied force and incurred displacement (or deflection) provides an instant evaluation of the stiffness of a part design. The proposed methodology is illustrated through a case study: the design of a toothbrush.     

一种柔性机器人的子杆法建模方法

本文实现了一种用虚拟刚性子杆及被动关节模型模拟柔性杆,进而对空间多杆柔性 机器人建模的方法;采用遗传算法解决了子杆参数的优化辨识问题;讨论了这一建模方法的 适用范围;并通过Raleigh阻尼的引入完善了这一方法;最后通过仿真初步验证了这一方法 的有效性和正确性．     

On the development of a haptic system for rapid product development

This paper presents a system development that extends haptic modeling to a number of key aspects in product development. Since haptic modeling has been developed based on physical laws, it is anticipated that a natural link between the virtual world and practical applications can be established based on haptic interaction. In the proposed system, a haptic device is used as the central mechanism for reverse engineering, shape modeling, real time mechanical property analysis, machining tool path planning and coordinate measuring machine (CMM) tolerance inspection path planning. With all these features in a single haptic system, it is possible to construct a three dimensional part by either haptic shape modeling or reverse engineering, then performing real-time mechanical property analysis in which the stiffness of a part can be felt and intuitively evaluated by the user, or generating collision free cutter tool path and CMM tolerance inspection path. Due to the force feed back in all of the above activities, the product development process is more intuitive, efficient and user-friendly. A prototype system has been developed to demonstrate the proposed capabilities.     

A cohesive modeling technique for theoretical and experimental estimation of damping in serial robots with rigid and flexible links

Dynamic model incorporating damping characteristics, namely joint damping and structural damping in flexible links, of the serial robots with rigid and flexible links is presented. A novel procedure, based on the unified approach of theoretical formulation and analysis of experimental data, is proposed for the estimation of damping coefficients. First, the dynamic model of a robotic system with rigid and flexible links is presented. Next, the modifications in the dynamic model due to the considerations of damping characteristics of joints and structural damping characteristics of the flexible links are presented. A systematic methodology based on analysis of data obtained from experiments is presented for estimation and determination of damping coefficients of rigid-flexible links. The determination of joint damping coefficients, is based on the logarithmic decay of the amplitude of the oscillations of robotic links, while the structural damping coefficients are estimated mainly using the modal analysis and the method of evolving spectra. The method of evolving spectra, based on the Fast Fourier Transform of the decay of the amplitude in structural vibrations of the robot links in progressive windows is used to estimate the structural damping ratios while the critical structural coefficients are determined using the modal analysis. The methodology is illustrated through a series of simple experiments on simple robotic systems. The experimental results are then compared with the simulation results incorporating the damping coefficients determined using the proposed procedure. The comparisons leads to the validation of the proposed dynamic modeling technique, modeling of the damping characteristics, and the method proposed for estimation of damping coefficients for rigid-flexible link robotic systems.     

应用于网上虚拟手术的自适应变形模型

提出并开发了一种适用于网上虚拟手术的自适应变形模型.在这个模型里,外力逐层地传播到软组织里,从而导致变形.通过控制外力的渗透深度,变形只局限在某些区域内发生,而模拟的计算量和准确性亦得以优化.该方法避免了在传统的质点弹簧模型中建立刚度矩阵的繁复程序.实验结果表明,这个模型可以用来模拟不同机械特性的材料,亦可用于在虚拟环境里模拟多用户的协同工作,或与多自由度的触觉式设备结合使用.     

A graph grammar-based formal validation of object-process diagrams

Two basic requirements from a system’s conceptual model are correctness and comprehensibility. Most modeling methodologies satisfy only one of these apparently contradicting requirements, usually comprehensibility, leaving aside problems of correctness and ambiguousness that are associated with expressiveness. Some formal modeling languages do exist, but in these languages a complete model of a complex system is fairly complicated to understand. Object-process methodology (OPM) is a holistic systems modeling methodology that combines the two major aspects of a system—structure and behavior—in one model, providing mechanisms to manage the complexity of the model using refinement-abstraction operations, which divide a complex system into many interconnected diagrams. Although the basic syntax and semantics of an OPM model are defined, they are incomplete and leave room for incorrect or ambiguous models. This work advances the formal definition of OPM by providing a graph grammar for creating and checking OPM diagrams. The grammar provides a validation methodology of the semantic and syntactic correctness of a single object-process diagram.     

Compact and lightweight optical torque sensor for robots with increased range

This paper describes the development of a compact and lightweight optical torque sensor for robots with increased range. The torque generated can only be measured by placing a torque sensor on each joint, which makes the joint bulky and heavy adding extra load to be carried by robots. In this paper, we propose a compact and lightweight design for the torque sensor. This sensor can measure torque of robot's links by detecting torsion. The optical technique is used to detect angular displacement in the joints. As optical technique is immune to electromagnetic interference, light weight, and it also required simple electronics. The torque can be calculated by using torque and twist angle relation. The proposed design is simulated by FEM software (ANSYS), and it shows successful measurements of the torque with a load capacity of 100 Nm, which is sufficient for the torque generated in robot's joints. The designed optical torque sensor is manufactured by electrical discharge machining (EDM). The optical torque sensor is calibrated and several experiments are conducted to ensure its feasibility with the robot.     

Bridging the HASM: An OWL ontology for modeling the information pathways in haptic interfaces software

Haptics technology has received enormous attention to enhance human computer interaction. The last decade has witnessed a rapid progress in haptic application software development due to the fact that the underlying technology has become mature and has opened up novel research areas. In an attempt to organize the path between cause and effect we envision a need for a standard for haptic application software modeling. In order for the software to better enhance the tactile information sensation, flow and perception and also make interaction between humans and haptics more efficient and natural, we need a formal representation of the haptics domain. This article proposes the use of HASM, a haptic applications software modeling ontology to formally model the haptics domain in order to be used during the specifications and design phases of developing software applications for haptic interfaces. The presented ontology captures the existing knowledge in haptics domain, using OWL, and defines the pathways that the haptic information follows between the human and the machine haptic system, using SWRL rules. The haptic ontology that has been developed will be used as a basis to design effective user interfaces and assist the development of software modeling for haptic devices. A case study is demonstrating how this haptic ontology can be used to design a software model that analyzes the perception of a haptic property of an object by interacting with a haptic device.     

基于UML的嵌入式系统建模及模型验证机制研究

统一建模语言UML在嵌入式系统设计建模中已经获得了广泛的认可,并有很多成功的应用,但UML存在时间约束描述能力不强和所建模型形式化复杂、验证难的问题。针对上述问题,本文提出了使用UML扩展机制对UML状态图进行时间扩展,建立系统状态一约束一事件矩阵来对模型进行形式化描述的方法。该方法解决了UML在嵌入式系统建模时存在的问题。应用实例和实验结果验证了该方法的可行性和有效性。     

An improved dynamic modeling of a multibody system with spherical joints

A dynamic modeling of multibody systems having spherical joints is reported in this work. In general, three intersecting orthogonal revolute joints are substituted for a spherical joint with vanishing lengths of intermediate links between the revolute joints. This procedure increases sizes of associated matrices in the equations of motion, thus increasing computational burden of an algorithm used for dynamic simulation and control. In the proposed methodology, Euler parameters, which are typically used for representation of a rigid-body orientation in three-dimensional Cartesian space, are employed to represent the orientation of a spherical joint that connects a link to its previous one providing three-degree-of-freedom motion capability. For the dynamic modeling, the concept of the Decoupled Natural Orthogonal Complement (DeNOC) matrices is utilized. It is shown in this work that the representation of spherical joints motion using Euler parameters avoids the unnecessary introduction of the intermediate links, thereby no increase in the sizes of the associated matrices with the dynamic equations of motion. To confirm the efficiency of the proposed representation, it is illustrated with the dynamic modeling of a spatial four-bar Revolute-Spherical–Spherical-Revolute (RSSR) mechanism, where the CPU time of the dynamic modeling based on proposed methodology is compared with that based on the revolute joints substitution. Finally, it is explained how a complex suspension and steering linkage can be modeled using the proposed concept of Euler parameters to represent a spherical joint.     

Design and kinetostatic analysis of a new parallel manipulator

This paper proposes an innovative design for a parallel manipulator that can be applied to a machine tool. The proposed parallel manipulator has three degrees of freedom (DOFs), including the rotations of a moving platform about the x and y axes and a translation of this platform along the z-axis. A passive link is introduced into this new parallel manipulator in order to increase the stiffness of the system and eliminate any unexpected motion. Both direct and inverse kinematic problems are investigated, and a dynamic model using a Newton–Euler approach is implemented. The global system stiffness of the proposed parallel manipulator, which considers the compliance of links and joints, is formulated and the kinetostatic analysis is conducted. Finally, a case study is presented to demonstrate the applications of the kinematic and dynamic models and to verify the concept of the new design.     

Stable haptic interaction using a damping model to implement a realistic tooth-cutting simulation for dental training

It is difficult to implement a stable and realistic haptic simulation for cutting rigid objects that is based on a damping model because of an inevitable conflict between stability and high output force. This paper presents passivity techniques to show that an excessive damping coefficient causes the output stiffness to exceed the maximum output stiffness of the haptic device, leading to instability. By analysing the damping model of a haptic dental-training simulator, we construct a relationship among the damping coefficient, position resolution, sampling frequency, human operation, and the maximum achievable device stiffness that will still maintain device stability. A method is also provided to restrict the output stiffness of the haptic device to ensure stability while enabling the realistic haptic simulation of cutting rigid objects (teeth) that is based in a damping model. Our analysis and conclusions are verified by a damping model that is constructed for a dental-training haptic display. Three types of haptic devices are used in our analysis and experiments.     

基于磁流变液的力/触觉再现系统研究进展

力/触觉再现技术是当前新兴的研究领域.介绍了最近10年来基于磁流变液的力/触觉再现系统的国内外研究进展情况.总结了基于磁流变液的力/触觉再现技术的研究内容,包括执行装置的结构设计、模型研究以及再现系统控制研究,讨论了基于磁流变液的力/触觉再现系统开发过程中的关键技术.如提高便携式触觉接口中执行装置的力矩/重量比.减小静态力、克服被动系统力/触觉表达局限性,指出了今后发展的趋势.阐述了基于磁流变液的力/触觉再现系统的优势,并展望了其应用前景.     

平面联接固定结合部动力学模型的一种建模方法

机械结构结合部精确建模是对含结合部的机械结构进行动态分析和优化设计的关键问题之一。文章主要研究块体结构和平板由螺栓联接后构成的固定结合部的动力学建模问题。将结合部区域的刚度特性用结合部的材料机械特性参数等效表达,提出了虚拟接触材料的结合部刚度表达模型。通过模态实验和模型修正识别出不同结合面工况下虚拟接触材料的弹性模量,建立了含结合部动力特性的有限元模型。该模型可方便用于含结合部结构的有限元计算,经试验验证满足实际工程应用要求。     

A new methodology for joint stiffness identification of heavy duty industrial robots with the counterbalancing system

This paper deals with the joint stiffness modeling and identification of the heavy duty industrial robot with the counterbalancing system (CBS), which is important for the workspace optimization and deflection compensation in the robotic manufacturing. Shortcomings of the traditional method for the joint stiffness modeling and corresponding identification are analyzed in this paper. Motivated by the advantage and limitations of the traditional approach, a new identification methodology based on the servo motor current and corresponding position deflection is proposed to obtain the accurate joint stiffness. To validate the effectiveness of the proposed method for the joint stiffness modeling and identification, an identification and validation experiment is carried out using the HH-150 heavy duty industrial robot. The results show that the proposed methodology is able to identify the joint stiffness of the heavy duty industrial robot with the CBS, and the proposed new methodology outperforms in terms of accuracy, convenience and efficiency for the joint stiffness identification.     

Determining model accuracy of network traces

Accurate network modeling is critical to the design of network protocols. Traditional modeling approaches, such as Discrete Time Markov Chains (DTMC) are limited in their ability to model time-varying characteristics. This problem is exacerbated in the wireless domain, where fading events create extreme burstiness of delays, losses, and errors on wireless links. In this paper, we describe the data preconditioning modeling technique that is capable of capturing the statistical characteristics of wired and wireless network traces. We revise our previous developed data preconditioning modeling algorithm, the Markov-based Trace Analysis (MTA), and present the Multiple states MTA (MMTA) algorithm. Our main contributions are methodologies created to quantify the accuracy of network models, methodology to choose the most accurate model for a given network and characteristic of interest (e.g., delay, loss, or error process), and the validation of our data preconditioning modeling algorithms.