Development of a flexible three-axial tactile sensor array for a robotic finger

In this paper, we propose a flexible three-axial tactile sensor array for measuring both normal and shear loads. The sensor array has 16 tactile sensor units based on piezoresistive strain gauge. It is constructed on a Kapton polyimide film using advanced polymer micromachining technologies. Thin metal strain gauges are embedded in polyimide to measure normal and shear loads, which are tested by applying forces from 0 to 1?N. The developed sensor unit had a hysteresis error of about 9% and repeatability error of about 1.31%. The sensor showed a good resulting image when pressed by a circle-shaped object with 10?N loads. The proposed flexible three-axial tactile sensor array can be applied in a curved or compliant surface that requires slip detection and flexibility, such as a robotic finger.     

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.     

Development of a sensor information integrated expert system for optimizing die polishing

This paper presents a polishing expert system integrated with sensor information which can modify the polishing sequence and conditions initially set by the system using the on-site polishing status detected. A practical system using AE sensors is developed for rotational and curved-surface polishing. A database and a knowledge base for polishing processes are established by using the results of experiments and also expert's experience. Evaluations are performed for a die of an automobile headlight lamp by using both the sensor-integrated expert system and the expert system without sensor. The results show that the sensor-integrated expert system provides more optimal polishing conditions since the proposed system takes advantage of the on-line sensor information.     

Development of tactile sensor for measuring hair touch feeling

In this paper, a tactile sensor system for evaluation of human hair under dry and wet conditions is developed. The polyvinylidene fluoride (PVDF) film is used as the sensory material. The sensor consists of an acrylic base, a silicone rubber, a PVDF film. A surface projection is put on the PVDF film as the contacting part. The sensor output is obtained by contacting and scanning objects. Panels imitating the physical and chemical properties of human hair surface are fabricated and used as measuring objects for stable measurement. Panels cleaned down with several kinds of hair-care products are measured by the sensor. By comparison between the sensor output and human sensory evaluation, it was confirmed that the sensor outputs have a good correlation with human sensory evaluation. It was found that the sensor system is available for monitoring hair conditions in both dry and wet conditions.     

Development of a bioinspired MEMS based capacitive tactile sensor for a robotic finger

This paper presents the development of a MEMS based capacitive tactile sensor intended to be incorporated into a tactile array as the core element of a biomimetic fingerpad. The use of standard microfabrication technologies in realising the device allowed a cost efficient fabrication involving only a few process steps. A low noise readout electronics system was developed for measuring the sensor response. The performance of both bare and packaged sensors was evaluated by direct probing of individual capacitive sensor units and characterising their response to load–unload indentation cycles.     

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.     

Design of a discrete Kalman filter for a tactile sensor in a feedback control system

This paper presents a design methodology for the optimum linear filter and predictor applied to robot sensor signals, as well as a sensitivity analysis of the kalman algorithms for uncertainties in the estimation of signal and noise parameters. Simulation of the filtration and prediction processes was made assuming a first-order spectrum of a pure signal and white measurement noise. Calculations of the algorithm errors, dependent on the accuracy of the signal and noise parameter estimation, were done for various spectra of the signal and for various signal-to-noise ratios. Furthermore, the sensitivity curves of the Kalman filter and predictor are presented. The outlined considerations might be helpful for designers when synthesizing optimum linear digital filters applied to sensor signals. Although that particular procedure has been designed for a robot tactile sensor application, the conclusions are more general, and applications may be found elsewhere.     

WTMS: a system for collecting and analyzing topic-specific Web information

With the explosive growth of the World Wide Web, it is becoming increasingly difficult for users to collect and analyze Web pages that are relevant to a particular topic. To address this problem we are developing WTMS, a system for Web topic management. In this paper we explain how the WTMS crawler efficiently collects Web pages for a topic. We also introduce the user interface of the system that integrates several techniques for analyzing the collection. Moreover, we present the various views of the interface that allow navigation through the information space. We highlight several examples to show how the system enables the user to gain useful insights about the collection.     

An optical tactile sensor for manipulators

A touch sensor for robots was designed, built and demonstrated. It is based on a deformable elastic reflective surface and optical fiber technology. The device is relatively immune to electromagnetic noise and may be used in environments where it is important to protect sensitive electronic equipment from such noise. The sensed touch pattern is easily read and interpreted by a computer using current video technology. The design allows for extremely high spatial resolution (2100 sensitive spots per square inch achieved here). Spatial resolution must be traded off with sensor pad thickness to retain adequate sensitivity.     

基于光学的触觉传感器电路设计

相较于电信号触觉传感器,基于光学的触觉传感器性能更好,受外界环境影响小,抗干扰性能更高.触觉传感器以弹性材料模拟人体皮肤,在弹性材料内部有标记点阵列.用摄像头拍摄标记点的图像,通过测量弹性材料受力发生形变时标记点阵列的位移情况来求解出力的分布情况,进一步计算出触觉信息.传感器采用EP4CGx30为主处理芯片,采用双层电路堆叠的方式实现,总尺寸为40mm×20mm×15 mm.     

基于FPGA的视频信息采集系统设计

文章介绍了一种基于FPGA的防信息泄漏视频信息采集系统.用可编程逻辑器件FPGA控制两片SDRAM交替读写.实现视频信号的无缝缓冲传输;在FPGA读取视频信息后.先用位面分层技术把串行视频信息转换为并行数据再送到视频电缆上.通过仿真和实验验证,该系统既满足视频系统对实时性的要求,又能有效降低视频信息在传输电统上的信息泄漏.     

Lump localisation through a deformation-based tactile feedback system using a biologically inspired finger sensor

The ability to localise harder areas in soft tissues is often desired during robot-assisted surgical operations. A deformation-based tactile feedback system was tested for the detection of objects within soft tissues, after being chosen over common pressure-based designs. This system uses a biologically inspired sensor that offers a new finger-like approach to tactile sensing. A tactile shape display developed from previous successful designs was used to output the sensed tactile information. Using the tactile feedback system on a mechanical teleoperated device, test subjects palpated a number of artificial tissue models to locate objects of varying stiffness. The addition of the tactile feedback system improved the detection of the objects from 64% to 98%, reduced the localisation error from 18 to 11 mm, and also decreased the time the users spent palpating the tissue from 55 to 37 s. This demonstrates that a deformation-based tactile feedback system can be used to successfully locate hard embedded objects within soft tissue, with a significant improvement over force and visual feedback alone. During testing, it was found that the users were able to more accurately locate the softest embedded objects compared to stiffer ones. Reasons for this observation are discussed.     

A new micromachined sensor system for tactile measurements of high aspect ratio microstructures

A new tactile sensor with piezoresistive read-out is presented. The sensor is designed for measurements of high aspect ratio structures with a resolution of some 10 nm and a measuring range of hundreds of micrometer. Possible applications of the sensor are suggested. The silicon micromachining fabrication process is shown in detail next to the finite element simulations we performed. First measurements and a calibration process are described and the results are shown. The implementation into a measuring system is indicated.     

基于CPLD的田径训练运动学信息采集系统

针对目前田径科学化训练手段比较单一，设计一种基于CPLD的田径训练运动学信息采集系统，该系统的核心技术是基于阵列柔性传感器研制的数字跑道。采用CPLD芯片实时检测、获取运动员训练时，其脚底与跑道接触的形状、时间等信息，同时系统的实时性和项目适应性也能得到保证，可用于其它需要测量步姿的场合。在用于数字跑道模块的实验中，该采集系统工作稳定，采集速度快，满足设计要求。     

Object imaging with a piezoelectric robotic tactile sensor

A two-dimensional, electrically multiplexed robotic tactile sensor was realized by coupling a piezoelectric polyvinylidene fluoride (PVDF) polymer film to a monolithic silicon integrated circuit (IC). The IC incorporates 64 sensor electrodes arranged in a symmetrical 8×8 matrix. Each electrode occupies a 400×400 μm square area, and they are separated from each other by 300 μm. A 40-μm-thick piezoelectric PVDF polymer film was attached to the electrode array with an electrically nonconductive methane adhesive. The response of the tactile sensor is linear for loads spanning 0.8-135 grams-of-force (gmf) (0.00-1.35 Newtons (N)). The response bandwidth is 25 Hz, the hysteresis level is tolerable, and, for operation in the sensor's linear range, taxel crosstalk is negligible. The historically persistent stability and response reproducibility limitation associated with piezoelectric-based tactile sensors has been solved by implementing a novel pre-charge voltage bias technique to initialize the pre- and post-load sensor responses. A rudimentary tactile object image measurement procedure for applied loads has been devised to recognize the silhouette of a sharp edge, square, trapezoid, isosceles triangle, circle, toroid, slotted screw, and cross-slotted screw     

Multiplexed piezoelectric polymer tactile sensor

An electrically multiplexed robotic tactile sensor has been realized using a monolithic silicon-integrated circuit coupled to a piezoelectric polyvinylidene fluoride (PVDF) film. The integrated circuit incorporates 25 sensor electrodes arranged in a symmetrical 5 × 5 matrix. Each electrode occupies a 600 × 600 m?m square area, and they are separated from each other by 600 m?m. A 25-m?m thick PVDF film was experimentally determined to be compatible with the fabrication process, and also yielded very favorable tactile sensing performance characteristics. The response of the tactile sensor is essentially linear for loads spanning 0.8 to 60 g force (gmf). The response bandwidth is 33 Hz, the hysteresis level is very small, and crosstalk is not a significant problem. A novel precharge bias scheme has been implemented to stabilize the pre- and postload sensor response. A rudimentary tactile object image measurement process was evaluated to recognize the shapes of circular, rectangular, toroidal, and hexagonal loads.     

A microcomputer system for collecting and processing physiological information about the masticatory system.

A software system has been written for IBM PC, XT, AT and compatible computers to be used for data collection, analysis and display. The system supports the sampling and processing of data for jaw movement tracks, myoelectrical activities of masticatory muscles, the temporomandibular joint (TMJ) and occlusal sounds and bite force, etc. The package includes the following functions: calculating displacement, velocity, curvature, and curvature center of jaw movement trace, analyzing myoelectrical signals in amplitude integration, root mean square and power spectrum, processing TMJ sounds and occlusal sounds and bite force, analysing jaw movement traces and myoelectrical activities during mastication simultaneously, determining the maxillomandibular relations, etc. The program also provides versatile formatting capability for video, printing and plotting of data, and graph creation. The most of the above programs have flexibility and adaptability to other physiological signal processes.     

Micromechanical three-axial tactile force sensor for micromaterial characterisation

 A three-axial tactile force sensor for the investigation of micromechanical structures has been developed using silicon micromachining technology. The sensor is capable of performing mechanical micro material characterisation such as the determination of the spring constant of complex micromechanical structures. Another application for this sensor is dimensional metrology where it has been tested as a 3D probe in a test set-up for coordinate measurements.     

Evaluation of a grey scale tactile array sensor pad for robotic applications

Since sensory feedback is an important part of robot control and the acquisition, manipulation, and recognition of objects, incorporating a sense of touch into a robotic system can greatly enhance the performance of that system. This article describes the evaluation of a recently developed low-resolution tactile array sensor pad system for use in robotic applications. Computer algorithms are developed which acquire data from the sensor pad and display the data on a CRT screen. Vision algorithms are implemented in order to extract the necessary information from the tactile data which will aid in the acquisition, manipulation, and recognition of objects. An object's pose is estimated by calculating its center of gravity (position) and principal axis (orientation). Recognizing an object and distinguishing between different objects is accomplished by implementing algorithms which estimate an object's perimeter (shape) and area (size). This work demonstrates that a low-resolution tactile array sensor is capable of providing the information that is required for many robotic applications in which objects must be acquired, manipulated, and recognized. Such a system provides a low-cost alternative to more conventional vision-based systems.