一种高分辨力柔性触觉传感器

本文描述了一种基于全内反射原理，用透明橡胶材料作为波导板的柔性触觉传感器。该传感器除具有一般刚性波导板触觉传感器的高分辨力等特点外，还具有柔性好，力灵敏阈值低，不怕碰撞等特点，该传感器特别适合装在智能机器人手爪上，为机器人系统高效率地获取物体形状，位置和姿态信息，实现智能抓握物体，操作物体等功能提供了有效的手段。     

Design and Developmental Metrics of a ‘Skin-Like’ Multi-Input Quasi-Compliant Robotic Gripper Sensor Using Tactile Matrix

Slip-resistant robust grasping of objects during remote manipulation remains one of the major open issues in robotics. Finer measurement of tangential force and slippage need to be considered for the task planning and control of robotic gripper in operation. Design and development of such a multi-sensory tactile array is reported in this paper, which is aimed for direct use in an instrumented jaw intelligent robot gripper for potentially hazardous radioactive environments. A new design has been reported in the paper, wherein sensing members of the prototype follow a combination of beam (bending) and truss-type (axial deformation) behavior under external loadings. Various characteristics of the sensor, viz. condition number, static and dynamic stiffness, sensitivity and repeatability have been evaluated, based on the results from field trials of the prototype. Besides the comparatively larger prototype, a miniaturized version of the sensor has also been developed and tested for object grasping in real-time.     

基于PVDF的三维力机器人触觉传感器的设计

当机器手抓取时物体受力信息检测是抓取过程顺利进行的基础,检测三维方向上的力便可充分反映物体的受力信息。当前用于抓取过程中三维力检测的触觉传感器还存在着一些不足,基于此,论文拟设计一种基于PVDF的三维力机器人触觉传感器。论文展示了传感器的结构设计,建立了压电薄膜及传感头结构的数学模型,设计了调理电路并对传感器进行测试和验证,结果表明该传感器能有效检测机器手抓取过程中的三维力信息。     

Intelligent robotic gripper with adaptive grasping force

The on-off control robot gripper is widely employed in pick-and-place operations in Cartesian space for handling hard objects between two positions. Without contact force monitoring, it can not be applied in fragile or soft objects handling. Although, an appropriate grasping force or gripper opening for each target could be searched by trial-and-error process, it needs expensive force/torque sensor or an accurate gripper position controller. It has too expensive and complex control strategy disadvantages for most of industrial applications. In addition, it can not overcome the target slip problem due to mass uncertainty and dynamic factor. Here, an intelligent gripper is designed with embedded distributed control structure for overcoming the uncertainty of object’s mass and soft/hard features. A communication signal is specified to integrate both robot arm and gripper control kernels for executing the robotic position control and gripper force control functions in sequence. An efficient model-free intelligent fuzzy sliding mode control strategy is employed to design the position and force controllers of gripper, respectively. Experimental results of pick-and-place soft and hard objects with grasping force auto-tuning and anti-slip control strategy are shown by pictures to verify the dynamic performance of this distributed control system. The position and force tracking errors are less than 1 mm and 0.1 N, respectively.

     

一种新型机器人三维力柔性触觉传感器的设计

基于柔性力敏导电橡胶材料,设计了一种能测量三维力的新型机器人柔性触觉传感器。研究了力敏导电橡胶材料的压阻效应,阐述了触觉传感器的设计思想,分别进行了触觉传感器单元设计和阵列结构设计和研究。获得了计算三维力的数学模型,并通过实验进行了三维力的验证。结果表明,设计的机器人三维力柔性触觉传感器具有设计简单,造价低廉,柔顺性好等优点,而且布置成阵列结构可用于医疗、体育、机器人等领域中检测三维力信息。     

A strategy for fast grasping of unknown objects using partial shape information from range sensors

In this paper, we present a strategy for fast grasping of unknown objects based on the partial shape information from range sensors for a mobile robot with a parallel-jaw gripper. The proposed method can realize fast grasping of an unknown object without needing complete information of the object or learning from grasping experience. Information regarding the shape of the object is acquired by a 2D range sensor installed on the robot at an inclined angle to the ground. Features for determining the maximal contact area are extracted directly from the partial shape information of the unknown object to determine the candidate grasping points. Note that since the shape and mass are unknown before grasping, a successful and stable grasp cannot be in fact guaranteed. Thus, after performing a grasping trial, the mobile robot uses the 2D range sensor to judge whether the object can be lifted. If a grasping trial fails, the mobile robot will quickly find other candidate grasping points for another trial until a successful and stable grasp is realized. The proposed approach has been tested in experiments, which found that a mobile robot with a parallel-jaw gripper can successfully grasp a wide variety of objects using the proposed algorithm. The results illustrate the validity of the proposed algorithm in term of the grasping time.     

Estimation of Grip Force and Slip Behavior During Robotic Grasp Using Data Fusion and Hypothesis Testing: Case Study with a Matrix Sensor

Algorithmic data fusion for multi-sensory system becomes extremely challenging, particularly where the elemental sensory units do vary in type, size and characteristics. Although traditional theories on sensory data fusion fit quite satisfactorily in searching a pre-defined object with a tentative dimension and depth perception, they fail to do justice in cases where profile of the object do vary from a point-mass to a finite spatial dimension. The present paper dwells on modeling, algorithm and experimental analysis of two novel fusion rule-bases, which are implemented in a small-sized tactile array sensor to be used in robot gripper. A new proposition has also been developed for assessing the decision threshold, signaling the presence of object inside the grasp-zone of the gripper. Besides, the developed model evaluates the approximate planar area of the grasped object alongwith its shape in real-time. The model also provides estimate for the gripping force required to sustain a stable grasp of the object vis-à-vis slippage characteristics, if any.     

Analysis and design of a new piezoresistive tactile sensor system for robotic applications

The development of an experimental tactile sensor system fitted on a robot work-table is analyzed in this paper. In the first stage of this research a 16 × 16 piezoresistive sensor was used, attached on the work-table of an ASEA IRB-2000 robot. The keypoint of the above design is that the sensor is not used just to obtain texture information, as it is happens when it is fitted on the gripper, but also to obtain tactile data from the object nonvisible base-surface and finally the object weight. The experimental system is designed so as to allow variation in the design parameters to determine the best set of parameter values for optimal performance of the sensor. Experiments carried out show the operability of the above system and, furthermore, the advantages using this sensor topology.     

Robust bin-picking system using tactile sensor

ABSTRACT

This paper presents a robust bin-picking system utilizing tactile sensors and a vision sensor. The object position and orientation are estimated using a fast template-matching method through the vision sensor. When a robot picks up an object, the tactile sensors detect the success or failure of the grasping, and a force sensor detects the contact with the environment. A weight sensor is also used to judge whether the lifting of the object has been successful. The robust and efficient bin-picking system presented herein is implemented through the integration of different sensors. In particular, the tactile sensors realize rope-shaped object picking that has yet to be made possible with conventional picking systems. The effectiveness of the proposed method was confirmed through grasping experiments and in a competitive event at the World Robot Challenge 2018.     

A servo-controlled robot gripper with multiple sensors and its logical specification

The logical specification of a microprocessor-based air-servo-controlled robot hand is presented, as well as its actual implementation. This hand can accommodate a wide variety of workpieces and allows for flexible assembly through the use of an automatic quick-change fingertip. The changeable set of gripper fingers is equipped with sensors, including a tactile force sensor, a crossfire sensor, a proximity sensor, and a slip sensor. A changeable set of gripper fingers with different sensing ranges can cope with certain subranges of the workpiece spectrum. A considerable cost saving is achieved by not changing the gripper itself. This specially designed hardware and software system includes position and force feedback. A PUMA 560 is used to test the success of the entire process.     

Development of soft and distributed tactile sensors and the application to a humanoid robot

This paper describes a comprehensive tactile sensor system which can cover wide areas of full-body robots. Based on design criteria which are introduced from requirements, we develop two types of tactile sensor elements. One is a multi-valued touch sensor which has multi-level pressure thresholds. It is capable of covering wide areas of robot surfaces. The other is made of soft, conductive gel, which has the advantage of compliance compared with other sheet-type tactile sensors. With these two types sensors, we develop the tactile sensor system on the full-body robot 'H4'. Details of the sensor system on the robot and some experiments using tactile information are described.     

用PVDF制作的机器人传感器

在分析PVDF敏感特性的基础上，阐述了用核材料研制的三维腕力传感器、阵列压力传感器及热觉传感器，给出了三种传感器的结构及相应信号处理方法．     

压阻式触觉传感器对法向力和剪切力的检测

灵活的触觉传感器应该具有像皮肤一样的功能,能够检测施加力的大小和方向.改进的压阻式触觉传感器,主要由中心芯和4个侧壁组成,法向力和剪切力的感测元件不同.将压阻式触觉传感器嵌入到一个聚二甲基硅氧烷(PDMS)弹性体中,以实现力的柔性检测.通过仿真分析,得到此种触觉传感器对法向力的检测范围为600 Pa~65 kPa,可测得的最小剪切力为900 Pa.通过进一步分析,得到施加法向力和剪切力时法向力感测元件阻值的变化曲线,可得此种触觉传感器能够有效降低法向力感测元件与剪切力感测元件之间的干扰.所开发的触觉传感器可以灵活检测施加的法向力和剪切力,可应用于机器人手臂和假肢上.     

Distributed cooperative control of multiple high-speed trains under a moving block system by nonlinear mapping-based feedback

Science China Information Sciences - The experiment on impedance adaptation to achieve stable grasp for an under-actuated gripper grasping different unknown objects with tactile array is conducted....     

Development of a smart handheld surgical tool with tactile feedback

This paper presents a handheld surgical tool adapting a tactile feedback system. The tool consists of a 3-degree-of-freedom (DOF) force sensor and three tactile displays. The sensor is easily embedded in the tool by adopting the capacitive transduction principle. The sensor measures the direction and magnitude of the 3-DOF force applied to the tool tip. The fingertip grasping the tool is stimulated by the tactile display to transmit the contact force information measured by the sensor. The tactile display is actuated by employing a soft actuator technology based on a dielectric elastomer actuator such as a type of electroactive polymer actuator. In this work, a prototype of the tool is designed and fabricated. Its performance is experimentally validated.     

敏感高分子“人工皮肤” 力觉感受器 的数学理论依据

本文以PVDF敏感材料的结构性能为出发点,对机器人触觉传感器——人工皮肤的理论基础进行了研究,并就PVDF的压电性从弹性力学的角度进行了分析。在此基础上给出了这一变形体的非线性动态系统的数学描述,为精确而有效地采集力觉感受器的压电信号奠定了基础,为机器人触觉力传感器的设计与制造提供了理论依据。     

Force control of a robot gripper based on human grasping schemes

This paper describes the force control of a robot gripper that is modeled on the basis of human grasping schemes. In the cases in which fluctuation in load is induced by movement of the object, human beings are able to precisely change the grasping forces according to changes in fingertip forces perpendicular to the grasping direction. The characteristics of strengthening and weakening of forces vary with respect to the safety margin. Here, a model for determining the grasping force of a robot gripper, which depends on the object's acceleration, is described. In this model, unexpected subtle load forces can be compensated by minimal required forces to prevent slip.     

水下机器人手爪力感知系统研究

提出了一种水下机器人手爪力感知系统的组成结构,该力感知系统由一个六维力/力矩传感器和三指夹持器指端的三个指力传感器组成,本文介绍了上述两种传感器的设计和标定,并对利用该手爪系统抓取物体进行了实际测试和分析,实验结果表明;所设计的力感知系统能够实时地感知腕力和夹持力信息,可以满足机械手力控制的需要.     

Comparison of contact sensor localization abilities during manipulation

This paper presents an experimental comparison of tactile array versus force-torque sensing for localizing contact during manipulation. The manipulation tasks involved rotating objects and translating objects using a planar two fingered manipulator. A pin and a box were selected as limiting cases of point and line contact against a cylindrical robot finger tip. Practical implementations of the two sensor types are compared theoretically and experimentally, and three different localization algorithms for the tactile array sensor are considered. Force-torque contact sensing results suffered from difficulties in calibration, transient forces, and low grasp force. Tactile array sensing was immune to these problems and the effect of shear loading was only noticeable for a simple centroid algorithm. The results show that with care, both of these sensing schemes can determine the contact location within a millimeter during real manipulation tasks.     

虚拟触觉传感器的仿真模型研究

本文根据真实触觉传感器的原理,对虚拟触觉传感器的仿真模型进行了研究,以便 在机器人手抓拾取操作中揭示与材料特性相关的触觉信息瞬态特性,进而为在虚拟环境中从 事基于传感信息的机器人柔性操作、精密装配操作等提供良好的研究平台．