Objekt-Manipulation und Steuerung der Greifkraft durch Verwendung von Taktilen Sensoren

This dissertation describes a new type of tactile sensor and an improved version of the dynamic tactile sensing approach that can provide a regularly updated and accurate estimate of minimum applied forces for use in the control of gripper manipulation. The pre-slip sensing algorithm is proposed and implemented into two-finger robot gripper. An algorithm that can discriminate between types of contact surface and recognize objects at the contact stage is also proposed. A technique for recognizing objects using tactile sensor arrays, and a method based on the quadric surface parameter for classifying grasped objects is described. Tactile arrays can recognize surface types on contact, making it possible for a tactile system to recognize translation, rotation, and scaling of an object independently.Diese Dissertation beschreibt eine neue Art von taktilen Sensoren und einen verbesserten Ansatz zur dynamischen Erfassung von taktilen daten, der in regelmäßigen Zeitabständen eine genaue Bewertung der minimalen Greifkraft liefert, die zur Steuerung des Greifers nötig ist. Ein Berechnungsverfahren zur Voraussage des Schlupfs, das in einen Zwei-Finger-Greifarm eines Roboters eingebaut wurde, wird vorgestellt. Auch ein Algorithmus zur Unterscheidung von verschiedenen Oberflächenarten und zur Erkennung von Objektformen bei der Berührung wird vorgestellt. Ein Verfahren zur Objekterkennung mit Hilfe einer Matrix aus taktilen Sensoren und eine Methode zur Klassifikation ergriffener Objekte, basierend auf den Daten einer rechteckigen Oberfläche, werden beschrieben. Mit Hilfe dieser Matrix können unter schiedliche Arten von Oberflächen bei Berührung erkannt werden, was es für das Tastsystem möglich macht, Verschiebung, Drehung und Größe eines Objektes unabhängig voneinander zu erkennen

Tactile-based Manipulation of Deformable Objects with Dynamic Center of Mass

International audienceTactile sensing feedback provides feasible solutions to robotic dexterous manipulation tasks. In this paper, we present a novel tactile-based framework for detecting/correcting slips and regulating grasping forces while manipulating de-formable objects with the dynamic center of mass. This framework consists of a tangential force based slip detection method and a deformation prevention approach relying on weight estimation. Moreover, we propose a new strategy for manipulating deformable heavy objects. Objects with different stiffnesses, surface textures, and centers of mass are tested in experiments. Results show that proposed approaches are capable of handling objects with uncertainties in their characteristics, and also robust to external disturbances

Microfabricated tactile sensors for biomedical applications: a review

During the last decades, tactile sensors based on different sensing principles have been developed due to the growing interest in robotics and, mainly, in medical applications. Several technological solutions have been employed to design tactile sensors; in particular, solutions based on microfabrication present several attractive features. Microfabrication technologies allow for developing miniaturized sensors with good performance in terms of metrological properties (e.g., accuracy, sensitivity, low power consumption, and frequency response). Small size and good metrological properties heighten the potential role of tactile sensors in medicine, making them especially attractive to be integrated in smart interfaces and microsurgical tools. This paper provides an overview of microfabricated tactile sensors, focusing on the mean principles of sensing, i.e., piezoresistive, piezoelectric and capacitive sensors. These sensors are employed for measuring contact properties, in particular force and pressure, in three main medical fields, i.e., prosthetics and artificial skin, minimal access surgery and smart interfaces for biomechanical analysis. The working principles and the metrological properties of the most promising tactile, microfabricated sensors are analyzed, together with their application in medicine. Finally, the new emerging technologies in these fields are briefly described

Sensors for Robotic Hands: A Survey of State of the Art

Recent decades have seen significant progress in the field of artificial hands. Most of the surveys, which try to capture the latest developments in this field, focused on actuation and control systems of these devices. In this paper, our goal is to provide a comprehensive survey of the sensors for artificial hands. In order to present the evolution of the field, we cover five year periods starting at the turn of the millennium. At each period, we present the robot hands with a focus on their sensor systems dividing them into categories, such as prosthetics, research devices, and industrial end-effectors.We also cover the sensors developed for robot hand usage in each era. Finally, the period between 2010 and 2015 introduces the reader to the state of the art and also hints to the future directions in the sensor development for artificial hands

Toward tactilely transparent gloves: Collocated slip sensing and vibrotactile actuation

Tactile information plays a critical role in the human ability to manipulate objects with one\u27s hands. Many environments require the use of protective gloves that diminish essential tactile feedback. Under these circumstances, seemingly simple tasks such as picking up an object can become very difficult. This paper introduces the SlipGlove, a novel device that uses an advanced sensing and actuation system to return this vital tactile information to the user. Our SlipGlove prototypes focus on providing tactile cues associated with slip between the glove and a contact surface. Relative motion is sensed using optical mouse sensors embedded in the glove\u27s surface. This information is conveyed to the wearer via miniature vibration motors placed inside the glove against the wearer\u27s skin. The collocation of slip sensing and tactile feedback creates a system that is natural and intuitive to use. We report results from a human subject study demonstrating that the SlipGlove allows the wearer to approach the capabilities of bare skin in detecting and reacting to fingertip slip. Users of the SlipGlove also had significantly faster and more consistent reaction to fingertip slip when compared to a traditional glove design. The SlipGlove technology allows us to enhance human perception when interacting with real environments and move toward the goal of a tactilely transparent glove

A Review of Non-Invasive Haptic Feedback stimulation Techniques for Upper Extremity Prostheses

A sense of touch is essential for amputees to reintegrate into their social and work life. The design of the next generation of the prostheses will have the ability to effectively convey the tactile information between the amputee and the artificial limbs. This work reviews non-invasive haptic feedback stimulation techniques to convey the tactile information from the prosthetic hand to the amputee’s brain. Various types of actuators that been used to stimulate the patient’s residual limb for different types of artificial prostheses in previous studies have been reviewed in terms of functionality, effectiveness, wearability and comfort. The non-invasive hybrid feedback stimulation system was found to be better in terms of the stimulus identification rate of the haptic prostheses’ users. It can be conclude that integrating hybrid haptic feedback stimulation system with the upper limb prostheses leads to improving its acceptance among users

Biomechanical Texture Coding and Transmission of Texture Information in Rat Whiskers

Classically, texture discrimination has been thought to be based on ‘global’ codes, i.e. frequency (signal analysis based on Fourier analysis) or intensity (signal analysis based on averaging), which both rely on integration of the vibrotactile signal across time and/or space. Recently, a novel ‘local’ coding scheme based on the waveform of frictional movements, discrete short- lasting kinematic events (i.e. stick-slip movements called slips) has been formulated. In the first part of my study I performed biomechanical measurements of relative movements of a rat vibrissa across sandpapers of different roughness. My major finding is that the classic global codes convey some information about texture identity but are consistently outperformed by the slip-based local code. Moreover, the slip code also surpasses the global ones in coding for active scanning parameters. This is remarkable as it suggests that the slip code would explicitly allow the whisking rat to optimize perception by selecting goal-specific scanning strategies. I therefore provide evidence that short stick-slip events may contribute to the perceptual mechanism by which rodent vibrissa code surface roughness. In the second part, I studied the biomechanics of how such events are transmitted from tip to follicle where mechano-transduction occurs. For this purpose, ultra-fast videography recording of the entire beam of a plucked rat whisker rubbing across sandpaper was employed. I found that slip events are conveyed almost instantly from tip to follicle while amplifying moments by a factor of about 1000. From these results, I argue that the mechanics of the whisker serve as a passive amplification device that faithfully represents stick-slip events to the neuronal receptors. Using measures of correlation, I moreover found that amongst the kinematic 8 variables, acceleration portrays dynamic variables (forces) best. The time series of acceleration at the base of the whisker provided a fair proxy to the time series of forces (dynamical variables) acting on the whisker base. Acceleration measurements (easily done via videography) may therefore provide an access to at least the relative amplitude of forces. This may be important for future work in behaving animals, where dynamical variables are notoriously difficult to measure