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Special Issue "Tactile Sensors and Sensing Systems"

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Physical Sensors".

Deadline for manuscript submissions: closed (15 December 2013)

Special Issue Editor

Guest Editor
Prof. Dr. Maurizio Valle

Department of Electrical, Electronic and Telecommunications Engineering, and Naval Architecture, University of Genova, Via Opera Pia 11A, I16145, Genova, Italy
Fax: +39 348 305 3884
Interests: tactile sensors; sensor interface electronics; microelectronics and nanoelectronics; sensor networks; embedded systems

Special Issue Information

Dear Colleagues,

Since early 80s, tactile sensing has been an evolving research field involving a strong interdisciplinary effort from researchers in different fields, namely electronics, mechanics, material science, measurement methods, system engineering, robotics and bioengineering, etc. Nonetheless only starting from last decade, the research community has been addressing the topic with a holistic approach putting on the field not only transducers development but also system integration and engineering issues.

In the meanwhile, the number of potential applications has increased very rapidly, e.g., humanoid and industrial robots, health care systems, medical instrumentation and prosthetic devices, augmented reality, human-machine interaction and many others. But established and reliable technologies and systems are still on the way.

In spite of the large and increasing interest and promising applications, tactile sensing is still in its infancy: remarkable examples of tactile sensing systems and technologies have been proposed yet their capability to address specific applications and their extension to other fields is questionable. Many technological and systems issues are still open and require a coordinated and strong effort to effectively address. Open issues involve, e.g., whole body awareness (i.e., large area skin), conformability and stretchability, structured design methodology, maintenance, calibration, system integration, interpretation of tactile data, reliability, fault tolerance and robustness, scalability, effective use of materials, small size and low power consumption, etc.

The special issue aims to provide an overview of current studies and achievements on tactile sensing, paving the way to its effective applications in real world.

Prof. Dr. Maurizio Valle
Guest Editor

Submission

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Keywords

  • smart and novel sensing materials
  • flexible and conformable sensors and arrays
  • sensors electronic interface
  • artificial skin
  • tactile data processing and interpretation
  • system integration
  • touch-based Human-Robot Interaction

Published Papers (17 papers)

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Research

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Open AccessArticle Computational Intelligence Techniques for Tactile Sensing Systems
Sensors 2014, 14(6), 10952-10976; doi:10.3390/s140610952
Received: 15 January 2014 / Revised: 5 June 2014 / Accepted: 10 June 2014 / Published: 19 June 2014
Cited by 2 | PDF Full-text (717 KB) | HTML Full-text | XML Full-text
Abstract
Tactile sensing helps robots interact with humans and objects effectively in real environments. Piezoelectric polymer sensors provide the functional building blocks of the robotic electronic skin, mainly thanks to their flexibility and suitability for detecting dynamic contact events and for recognizing the [...] Read more.
Tactile sensing helps robots interact with humans and objects effectively in real environments. Piezoelectric polymer sensors provide the functional building blocks of the robotic electronic skin, mainly thanks to their flexibility and suitability for detecting dynamic contact events and for recognizing the touch modality. The paper focuses on the ability of tactile sensing systems to support the challenging recognition of certain qualities/modalities of touch. The research applies novel computational intelligence techniques and a tensor-based approach for the classification of touch modalities; its main results consist in providing a procedure to enhance system generalization ability and architecture for multi-class recognition applications. An experimental campaign involving 70 participants using three different modalities in touching the upper surface of the sensor array was conducted, and confirmed the validity of the approach. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Open AccessArticle Integration of Fiber-Optic Sensor Arrays into a Multi-Modal Tactile Sensor Processing System for Robotic End-Effectors
Sensors 2014, 14(4), 6854-6876; doi:10.3390/s140406854
Received: 7 January 2014 / Revised: 1 April 2014 / Accepted: 11 April 2014 / Published: 16 April 2014
Cited by 3 | PDF Full-text (4952 KB) | HTML Full-text | XML Full-text
Abstract
With the increasing complexity of robotic missions and the development towards long-term autonomous systems, the need for multi-modal sensing of the environment increases. Until now, the use of tactile sensor systems has been mostly based on sensing one modality of forces in [...] Read more.
With the increasing complexity of robotic missions and the development towards long-term autonomous systems, the need for multi-modal sensing of the environment increases. Until now, the use of tactile sensor systems has been mostly based on sensing one modality of forces in the robotic end-effector. The use of a multi-modal tactile sensory system is motivated, which combines static and dynamic force sensor arrays together with an absolute force measurement system. This publication is focused on the development of a compact sensor interface for a fiber-optic sensor array, as optic measurement principles tend to have a bulky interface. Mechanical, electrical and software approaches are combined to realize an integrated structure that provides decentralized data pre-processing of the tactile measurements. Local behaviors are implemented using this setup to show the effectiveness of this approach. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Open AccessArticle Contact Region Estimation Based on a Vision-Based Tactile Sensor Using a Deformable Touchpad
Sensors 2014, 14(4), 5805-5822; doi:10.3390/s140405805
Received: 30 January 2014 / Revised: 10 March 2014 / Accepted: 20 March 2014 / Published: 25 March 2014
PDF Full-text (861 KB) | HTML Full-text | XML Full-text
Abstract
A new method is proposed to estimate the contact region between a sensor and an object using a deformable tactile sensor. The sensor consists of a charge-coupled device (CCD) camera, light-emitting diode (LED) lights and a deformable touchpad. The sensor can obtain [...] Read more.
A new method is proposed to estimate the contact region between a sensor and an object using a deformable tactile sensor. The sensor consists of a charge-coupled device (CCD) camera, light-emitting diode (LED) lights and a deformable touchpad. The sensor can obtain a variety of tactile information, such as the contact region, multi-axis contact force, slippage, shape, position and orientation of an object in contact with the touchpad. The proposed method is based on the movements of dots printed on the surface of the touchpad and classifies the contact state of dots into three types—A non-contacting dot, a sticking dot and a slipping dot. Considering the movements of the dots with noise and errors, equations are formulated to discriminate between the contacting dots and the non-contacting dots. A set of the contacting dots discriminated by the formulated equations can construct the contact region. Next, a method is developed to detect the dots in images of the surface of the touchpad captured by the CCD camera. A method to assign numbers to dots for calculating the displacements of the dots is also proposed. Finally, the proposed methods are validated by experimental results. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Open AccessArticle A Finger-Shaped Tactile Sensor for Fabric Surfaces Evaluation by 2-Dimensional Active Sliding Touch
Sensors 2014, 14(3), 4899-4913; doi:10.3390/s140304899
Received: 8 January 2014 / Revised: 12 February 2014 / Accepted: 18 February 2014 / Published: 11 March 2014
Cited by 7 | PDF Full-text (504 KB) | HTML Full-text | XML Full-text
Abstract
Sliding tactile perception is a basic function for human beings to determine the mechanical properties of object surfaces and recognize materials. Imitating this process, this paper proposes a novel finger-shaped tactile sensor based on a thin piezoelectric polyvinylidene fluoride (PVDF) film for [...] Read more.
Sliding tactile perception is a basic function for human beings to determine the mechanical properties of object surfaces and recognize materials. Imitating this process, this paper proposes a novel finger-shaped tactile sensor based on a thin piezoelectric polyvinylidene fluoride (PVDF) film for surface texture measurement. A parallelogram mechanism is designed to ensure that the sensor applies a constant contact force perpendicular to the object surface, and a 2-dimensional movable mechanical structure is utilized to generate the relative motion at a certain speed between the sensor and the object surface. By controlling the 2-dimensional motion of the finger-shaped sensor along the object surface, small height/depth variation of surface texture changes the output charge of PVDF film then surface texture can be measured. In this paper, the finger-shaped tactile sensor is used to evaluate and classify five different kinds of linen. Fast Fourier Transformation (FFT) is utilized to get original attribute data of surface in the frequency domain, and principal component analysis (PCA) is used to compress the attribute data and extract feature information. Finally, low dimensional features are classified by Support Vector Machine (SVM). The experimental results show that this finger-shaped tactile sensor is effective and high accurate for discriminating the five textures. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Open AccessArticle Intrinsic Embedded Sensors for Polymeric Mechatronics: Flexure and Force Sensing
Sensors 2014, 14(3), 3861-3870; doi:10.3390/s140303861
Received: 16 December 2013 / Revised: 12 February 2014 / Accepted: 19 February 2014 / Published: 25 February 2014
Cited by 3 | PDF Full-text (641 KB) | HTML Full-text | XML Full-text
Abstract
While polymeric fabrication processes, including recent advances in additive manufacturing, have revolutionized manufacturing, little work has been done on effective sensing elements compatible with and embedded within polymeric structures. In this paper, we describe the development and evaluation of two important sensing [...] Read more.
While polymeric fabrication processes, including recent advances in additive manufacturing, have revolutionized manufacturing, little work has been done on effective sensing elements compatible with and embedded within polymeric structures. In this paper, we describe the development and evaluation of two important sensing modalities for embedding in polymeric mechatronic and robotic mechanisms: multi-axis flexure joint angle sensing utilizing IR phototransistors, and a small (12 mm), three-axis force sensing via embedded silicon strain gages with similar performance characteristics as an equally sized metal element based sensor. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Open AccessArticle Object Recognition and Localization: The Role of Tactile Sensors
Sensors 2014, 14(2), 3227-3266; doi:10.3390/s140203227
Received: 23 December 2013 / Revised: 31 January 2014 / Accepted: 8 February 2014 / Published: 18 February 2014
Cited by 5 | PDF Full-text (10257 KB) | HTML Full-text | XML Full-text
Abstract
Tactile sensors, because of their intrinsic insensitivity to lighting conditions and water turbidity, provide promising opportunities for augmenting the capabilities of vision sensors in applications involving object recognition and localization. This paper presents two approaches for haptic object recognition and localization for [...] Read more.
Tactile sensors, because of their intrinsic insensitivity to lighting conditions and water turbidity, provide promising opportunities for augmenting the capabilities of vision sensors in applications involving object recognition and localization. This paper presents two approaches for haptic object recognition and localization for ground and underwater environments. The first approach called Batch Ransac and Iterative Closest Point augmented Particle Filter (BRICPPF) is based on an innovative combination of particle filters, Iterative-Closest-Point algorithm, and a feature-based Random Sampling and Consensus (RANSAC) algorithm for database matching. It can handle a large database of 3D-objects of complex shapes and performs a complete six-degree-of-freedom localization of static objects. The algorithms are validated by experimentation in ground and underwater environments using real hardware. To our knowledge this is the first instance of haptic object recognition and localization in underwater environments. The second approach is biologically inspired, and provides a close integration between exploration and recognition. An edge following exploration strategy is developed that receives feedback from the current state of recognition. A recognition by parts approach is developed which uses the BRICPPF for object sub-part recognition. Object exploration is either directed to explore a part until it is successfully recognized, or is directed towards new parts to endorse the current recognition belief. This approach is validated by simulation experiments. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Open AccessArticle Driving Interface Based on Tactile Sensors for Electric Wheelchairs or Trolleys
Sensors 2014, 14(2), 2644-2662; doi:10.3390/s140202644
Received: 28 December 2013 / Revised: 15 January 2014 / Accepted: 17 January 2014 / Published: 10 February 2014
Cited by 2 | PDF Full-text (1504 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This paper introduces a novel device based on a tactile interface to replace the attendant joystick in electric wheelchairs. It can also be used in other vehicles such as shopping trolleys. Its use allows intuitive driving that requires little or no training, [...] Read more.
This paper introduces a novel device based on a tactile interface to replace the attendant joystick in electric wheelchairs. It can also be used in other vehicles such as shopping trolleys. Its use allows intuitive driving that requires little or no training, so its usability is high. This is achieved by a tactile sensor located on the handlebar of the chair or trolley and the processing of the information provided by it. When the user interacts with the handle of the chair or trolley, he or she exerts a pressure pattern that depends on the intention to accelerate, brake or turn to the left or right. The electronics within the device then perform the signal conditioning and processing of the information received, identifying the intention of the user on the basis of this pattern using an algorithm, and translating it into control signals for the control module of the wheelchair. These signals are equivalent to those provided by a joystick. This proposal aims to help disabled people and their attendees and prolong the personal autonomy in a context of aging populations. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Open AccessArticle Seeing by Touch: Evaluation of a Soft Biologically-Inspired Artificial Fingertip in Real-Time Active Touch
Sensors 2014, 14(2), 2561-2577; doi:10.3390/s140202561
Received: 25 December 2013 / Revised: 23 January 2014 / Accepted: 27 January 2014 / Published: 7 February 2014
Cited by 6 | PDF Full-text (523 KB) | HTML Full-text | XML Full-text
Abstract
Effective tactile sensing for artificial platforms remains an open issue in robotics. This study investigates the performance of a soft biologically-inspired artificial fingertip in active exploration tasks. The fingertip sensor replicates the mechanisms within human skin and offers a robust solution that [...] Read more.
Effective tactile sensing for artificial platforms remains an open issue in robotics. This study investigates the performance of a soft biologically-inspired artificial fingertip in active exploration tasks. The fingertip sensor replicates the mechanisms within human skin and offers a robust solution that can be used both for tactile sensing and gripping/manipulating objects. The softness of the optical sensor’s contact surface also allows safer interactions with objects. High-level tactile features such as edges are extrapolated from the sensor’s output and the information is used to generate a tactile image. The work presented in this paper aims to investigate and evaluate this artificial fingertip for 2D shape reconstruction. The sensor was mounted on a robot arm to allow autonomous exploration of different objects. The sensor and a number of human participants were then tested for their abilities to track the raised perimeters of different planar objects and compared. By observing the technique and accuracy of the human subjects, simple but effective parameters were determined in order to evaluate the artificial system’s performance. The results prove the capability of the sensor in such active exploration tasks, with a comparable performance to the human subjects despite it using tactile data alone whereas the human participants were also able to use proprioceptive cues. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Figures

Open AccessArticle A Two-Ply Polymer-Based Flexible Tactile Sensor Sheet Using Electric Capacitance
Sensors 2014, 14(2), 2225-2238; doi:10.3390/s140202225
Received: 24 December 2013 / Revised: 14 January 2014 / Accepted: 23 January 2014 / Published: 29 January 2014
Cited by 2 | PDF Full-text (416 KB) | HTML Full-text | XML Full-text
Abstract
Traditional capacitive tactile sensor sheets usually have a three-layered structure, with a dielectric layer sandwiched by two electrode layers. Each electrode layer has a number of parallel ribbon-like electrodes. The electrodes on the two electrode layers are oriented orthogonally and each crossing [...] Read more.
Traditional capacitive tactile sensor sheets usually have a three-layered structure, with a dielectric layer sandwiched by two electrode layers. Each electrode layer has a number of parallel ribbon-like electrodes. The electrodes on the two electrode layers are oriented orthogonally and each crossing point of the two perpendicular electrode arrays makes up a capacitive sensor cell on the sheet. It is well known that compatibility between measuring precision and resolution is difficult, since decreasing the width of the electrodes is required to obtain a high resolution, however, this may lead to reduction of the area of the sensor cells, and as a result, lead to a low Signal/Noise (S/N) ratio. To overcome this problem, a new multilayered structure and related calculation procedure are proposed. This new structure stacks two or more sensor sheets with shifts in position. Both a high precision and a high resolution can be obtained by combining the signals of the stacked sensor sheets. Trial production was made and the effect was confirmed. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Open AccessArticle Control Framework for Dexterous Manipulation Using Dynamic Visual Servoing and Tactile Sensors’ Feedback
Sensors 2014, 14(1), 1787-1804; doi:10.3390/s140101787
Received: 16 December 2013 / Revised: 10 January 2014 / Accepted: 15 January 2014 / Published: 21 January 2014
Cited by 7 | PDF Full-text (654 KB) | HTML Full-text | XML Full-text
Abstract
Tactile sensors play an important role in robotics manipulation to perform dexterous and complex tasks. This paper presents a novel control framework to perform dexterous manipulation with multi-fingered robotic hands using feedback data from tactile and visual sensors. This control framework permits [...] Read more.
Tactile sensors play an important role in robotics manipulation to perform dexterous and complex tasks. This paper presents a novel control framework to perform dexterous manipulation with multi-fingered robotic hands using feedback data from tactile and visual sensors. This control framework permits the definition of new visual controllers which allow the path tracking of the object motion taking into account both the dynamics model of the robot hand and the grasping force of the fingertips under a hybrid control scheme. In addition, the proposed general method employs optimal control to obtain the desired behaviour in the joint space of the fingers based on an indicated cost function which determines how the control effort is distributed over the joints of the robotic hand. Finally, authors show experimental verifications on a real robotic manipulation system for some of the controllers derived from the control framework. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Open AccessArticle Micro-Vibration-Based Slip Detection in Tactile Force Sensors
Sensors 2014, 14(1), 709-730; doi:10.3390/s140100709
Received: 5 November 2013 / Revised: 6 December 2013 / Accepted: 27 December 2013 / Published: 3 January 2014
Cited by 5 | PDF Full-text (1527 KB) | HTML Full-text | XML Full-text
Abstract
Tactile sensing provides critical information, such as force, texture, shape or temperature, in manipulation tasks. In particular, tactile sensors traditionally used in robotics are emphasized in contact force determination for grasping control and object recognition. Nevertheless, slip detection is also crucial to [...] Read more.
Tactile sensing provides critical information, such as force, texture, shape or temperature, in manipulation tasks. In particular, tactile sensors traditionally used in robotics are emphasized in contact force determination for grasping control and object recognition. Nevertheless, slip detection is also crucial to successfully manipulate an object. Several approaches have appeared to detect slipping, the majority being a combination of complex sensors with complex algorithms. In this paper, we deal with simplicity, analyzing how a novel, but simple, algorithm, based on micro-vibration detection, can be used in a simple, but low-cost and durable, force sensor. We also analyze the results of using the same principle to detect slipping in other force sensors based on flexible parts. In particular, we show and compare the slip detection with: (i) a flexible finger, designed by the authors, acting as a force sensor; (ii) the finger torque sensor of a commercial robotic hand; (iii) a commercial six-axis force sensor mounted on the wrist of a robot; and (iv) a fingertip piezoresistive matrix sensor. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Figures

Open AccessArticle Active Design Method for the Static Characteristics of a Piezoelectric Six-Axis Force/Torque Sensor
Sensors 2014, 14(1), 659-671; doi:10.3390/s140100659
Received: 11 October 2013 / Revised: 15 December 2013 / Accepted: 23 December 2013 / Published: 2 January 2014
Cited by 3 | PDF Full-text (701 KB) | HTML Full-text | XML Full-text
Abstract
To address the bottleneck issues of an elastic-style six-axis force/torque sensor (six-axis force sensor), this work proposes a no-elastic piezoelectric six-axis force sensor. The operating principle of the piezoelectric six-axis force sensor is analyzed, and a structural model is constructed. The static-active [...] Read more.
To address the bottleneck issues of an elastic-style six-axis force/torque sensor (six-axis force sensor), this work proposes a no-elastic piezoelectric six-axis force sensor. The operating principle of the piezoelectric six-axis force sensor is analyzed, and a structural model is constructed. The static-active design theory of the piezoelectric six-axis force sensor is established, including a static analytical/mathematical model and numerical simulation model (finite element model). A piezoelectric six-axis force sensor experimental prototype is developed according to the analytical mathematical model and numerical simulation model, and selected static characteristic parameters (including sensitivity, isotropic degree and cross-coupling) are tested using this model with three approaches. The measured results are in agreement with the analytical results from the static-active design method. Therefore, this study has successfully established a foundation for further research into the piezoelectric multi-axis force sensor and an overall design approach based on static characteristics. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Figures

Open AccessArticle P(VDF-TrFE) Polymer-Based Thin Films Deposited on Stainless Steel Substrates Treated Using Water Dissociation for Flexible Tactile Sensor Development
Sensors 2013, 13(11), 14777-14796; doi:10.3390/s131114777
Received: 15 August 2013 / Revised: 11 October 2013 / Accepted: 23 October 2013 / Published: 30 October 2013
Cited by 3 | PDF Full-text (1050 KB) | HTML Full-text | XML Full-text
Abstract
In this work, deionized (DI) water dissociation was used to treat and change the contact angle of the surface of stainless steel substrates followed by the spin coating of P(VDF-TrFE) material for the fabrication of tactile sensors. The contact angle of the [...] Read more.
In this work, deionized (DI) water dissociation was used to treat and change the contact angle of the surface of stainless steel substrates followed by the spin coating of P(VDF-TrFE) material for the fabrication of tactile sensors. The contact angle of the stainless steel surface decreased 14° at −30 V treatment; thus, the adhesion strength between the P(VDF-TrFE) thin film and the stainless steel substrate increased by 90%. Although the adhesion strength was increased at negative voltage treatment, it is observed that the crystallinity value of the P(VDF-TrFE) thin film declined to 37% at −60 V. In addition, the remanent polarization value of the P(VDF-TrFE) thin film declined from 5.6 mC/cm2 to 4.61 mC/cm2 for treatment voltages between −5 V and −60 V. A maximum value of approximately 1000 KV/cm of the coercive field value was obtained with the treatment at −15 V. The d33 value was approximately −10.7 pC/N for the substrate treated at 0 V and reached a minimum of −5 pC/N for treatment at −60 V. By using the P(VDF-TrFE) thin-film as the sensing material for tactile sensors, human pulse measurements were obtained from areas including the carotid, brachial, ankle, radial artery, and apical regions. In addition, the tactile sensor is suitable for monitoring the Cun, Guan, and Chi acupoints located at the radial artery region in Traditional Chinese Medicine (TCM). Waveform measurements of the Cun, Guan, and Chi acupoints are crucial because, in TCM, the various waveforms provided information regarding the health conditions of organs. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Open AccessArticle Force Sensitive Handles and Capacitive Touch Sensor for Driving a Flexible Haptic-Based Immersive System
Sensors 2013, 13(10), 13487-13508; doi:10.3390/s131013487
Received: 8 July 2013 / Revised: 20 September 2013 / Accepted: 24 September 2013 / Published: 9 October 2013
Cited by 4 | PDF Full-text (17302 KB) | HTML Full-text | XML Full-text
Abstract
In this article, we present an approach that uses both two force sensitive handles (FSH) and a flexible capacitive touch sensor (FCTS) to drive a haptic-based immersive system. The immersive system has been developed as part of a multimodal interface for product [...] Read more.
In this article, we present an approach that uses both two force sensitive handles (FSH) and a flexible capacitive touch sensor (FCTS) to drive a haptic-based immersive system. The immersive system has been developed as part of a multimodal interface for product design. The haptic interface consists of a strip that can be used by product designers to evaluate the quality of a 3D virtual shape by using touch, vision and hearing and, also, to interactively change the shape of the virtual object. Specifically, the user interacts with the FSH to move the virtual object and to appropriately position the haptic interface for retrieving the six degrees of freedom required for both manipulation and modification modalities. The FCTS allows the system to track the movement and position of the user’s fingers on the strip, which is used for rendering visual and sound feedback. Two evaluation experiments are described, which involve both the evaluation and the modification of a 3D shape. Results show that the use of the haptic strip for the evaluation of aesthetic shapes is effective and supports product designers in the appreciation of the aesthetic qualities of the shape. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Open AccessArticle Application of a Force Sensor to Improve the Reliability of Measurement with Articulated Arm Coordinate Measuring Machines
Sensors 2013, 13(8), 10430-10448; doi:10.3390/s130810430
Received: 8 June 2013 / Revised: 22 July 2013 / Accepted: 8 August 2013 / Published: 13 August 2013
Cited by 10 | PDF Full-text (875 KB) | HTML Full-text | XML Full-text
Abstract
A study of the operator contact force influence on the performance of Articulated Arm Coordinate Measuring Machines (AACMMs) is presented in this paper. After developing a sensor capable of measuring the contact force applied by an operator, a ring gauge has been [...] Read more.
A study of the operator contact force influence on the performance of Articulated Arm Coordinate Measuring Machines (AACMMs) is presented in this paper. After developing a sensor capable of measuring the contact force applied by an operator, a ring gauge has been used to analyse the relationship between the contact force and diameter and form errors measured with the AACMM. As a result, contact force has been proved as one of the main factors influencing the AACMM performance. A probe deflection model based on the Finite Element Method (FEM) has been also proposed in order to obtain the AACMM probe deflection caused by contact force. This allows measurement correction by comparing them with reference values, specifically, a ring gauge. Experimental test results show a significant measurement improvement that minimizes diameter error. Finally, an uncertainty evaluation for the contact force sensor and AACMM measurements with and without probe deflection model has been carried out in order to validate the ability of the sensor and the methodology followed. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)
Open AccessArticle Measuring Center of Pressure Signals to Quantify Human Balance Using Multivariate Multiscale Entropy by Designing a Force Platform
Sensors 2013, 13(8), 10151-10166; doi:10.3390/s130810151
Received: 3 June 2013 / Revised: 27 July 2013 / Accepted: 1 August 2013 / Published: 8 August 2013
Cited by 10 | PDF Full-text (510 KB) | HTML Full-text | XML Full-text
Abstract
To assess the improvement of human body balance, a low cost and portable measuring device of center of pressure (COP), known as center of pressure and complexity monitoring system (CPCMS), has been developed for data logging and analysis. In order to prove [...] Read more.
To assess the improvement of human body balance, a low cost and portable measuring device of center of pressure (COP), known as center of pressure and complexity monitoring system (CPCMS), has been developed for data logging and analysis. In order to prove that the system can estimate the different magnitude of different sways in comparison with the commercial Advanced Mechanical Technology Incorporation (AMTI) system, four sway tests have been developed (i.e., eyes open, eyes closed, eyes open with water pad, and eyes closed with water pad) to produce different sway displacements. Firstly, static and dynamic tests were conducted to investigate the feasibility of the system. Then, correlation tests of the CPCMS and AMTI systems have been compared with four sway tests. The results are within the acceptable range. Furthermore, multivariate empirical mode decomposition (MEMD) and enhanced multivariate multiscale entropy (MMSE) analysis methods have been used to analyze COP data reported by the CPCMS and compare it with the AMTI system. The improvements of the CPCMS are 35% to 70% (open eyes test) and 60% to 70% (eyes closed test) with and without water pad. The AMTI system has shown an improvement of 40% to 80% (open eyes test) and 65% to 75% (closed eyes test). The results indicate that the CPCMS system can achieve similar results to the commercial product so it can determine the balance. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)

Review

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Open AccessReview Flexible Tactile Sensing Based on Piezoresistive Composites: A Review
Sensors 2014, 14(3), 5296-5332; doi:10.3390/s140305296
Received: 2 January 2014 / Revised: 7 February 2014 / Accepted: 18 February 2014 / Published: 14 March 2014
Cited by 41 | PDF Full-text (2802 KB) | HTML Full-text | XML Full-text
Abstract
The large expansion of the robotic field in the last decades has created a growing interest in the research and development of tactile sensing solutions for robot hand and body integration. Piezoresistive composites are one of the most widely employed materials for [...] Read more.
The large expansion of the robotic field in the last decades has created a growing interest in the research and development of tactile sensing solutions for robot hand and body integration. Piezoresistive composites are one of the most widely employed materials for this purpose, combining simple and low cost preparation with high flexibility and conformability to surfaces, low power consumption, and the use of simple read-out electronics. This work provides a review on the different type of composite materials, classified according to the conduction mechanism and analyzing the physics behind it. In particular piezoresistors, strain gauges, percolative and quantum tunnelling devices are reviewed here, with a perspective overview on the most used filler types and polymeric matrices. A description of the state-of-the-art of the tactile sensor solutions from the point of view of the architecture, the design and the performance is also reviewed, with a perspective outlook on the main promising applications. Full article
(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)

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