Stretchable capacitive tactile skin on humanoid robot fingers - first experiments and results

A stretchable tactile sensor skin has been demonstrated on the dorsal side of a robotic hand for the first time. The sensors can detect normal pressures on the same scale as human skin but also in excess of 250 kPa and withstand strains in excess of 15%. Using tactile information from the sensors mounted on a glove worn by a humanoid robot's hand, obstacle detection and surface reconstruction tasks were successfully completed in order to demonstrate the performance of the sensors under applied strains and pressure

Comparing Piezoresistive Substrates for Tactile Sensing in Dexterous Hands

While tactile skins have been shown to be useful for detecting collisions between a robotic arm and its environment, they have not been extensively used for improving robotic grasping and in-hand manipulation. We propose a novel sensor design for use in covering existing multi-fingered robot hands. We analyze the performance of four different piezoresistive materials using both fabric and anti-static foam substrates in benchtop experiments. We find that although the piezoresistive foam was designed as packing material and not for use as a sensing substrate, it performs comparably with fabrics specifically designed for this purpose. While these results demonstrate the potential of piezoresistive foams for tactile sensing applications, they do not fully characterize the efficacy of these sensors for use in robot manipulation. As such, we use a high density foam substrate to develop a scalable tactile skin that can be attached to the palm of a robotic hand. We demonstrate several robotic manipulation tasks using this sensor to show its ability to reliably detect and localize contact, as well as analyze contact patterns during grasping and transport tasks.Comment: 10 figures, 8 pages, submitted to ICRA 202

Chapter Large Scale Capacitive Skin for Robots

Communications engineering / telecommunication

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

An Embedded, Multi-Modal Sensor System for Scalable Robotic and Prosthetic Hand Fingers

Grasping and manipulation with anthropomorphic robotic and prosthetic hands presents a scientific challenge regarding mechanical design, sensor system, and control. Apart from the mechanical design of such hands, embedding sensors needed for closed-loop control of grasping tasks remains a hard problem due to limited space and required high level of integration of different components. In this paper we present a scalable design model of artificial fingers, which combines mechanical design and embedded electronics with a sophisticated multi-modal sensor system consisting of sensors for sensing normal and shear force, distance, acceleration, temperature, and joint angles. The design is fully parametric, allowing automated scaling of the fingers to arbitrary dimensions in the human hand spectrum. To this end, the electronic parts are composed of interchangeable modules that facilitate the echanical scaling of the fingers and are fully enclosed by the mechanical parts of the finger. The resulting design model allows deriving freely scalable and multimodally sensorised fingers for robotic and prosthetic hands. Four physical demonstrators are assembled and tested to evaluate the approach

An Embedded, Multi-Modal Sensor System for Scalable Robotic and Prosthetic Hand Fingers

Grasping and manipulation with anthropomorphic robotic and prosthetic hands presents a scientific challenge regarding mechanical design, sensor system, and control. Apart from the mechanical design of such hands, embedding sensors needed for closed-loop control of grasping tasks remains a hard problem due to limited space and required high level of integration of different components. In this paper we present a scalable design model of artificial fingers, which combines mechanical design and embedded electronics with a sophisticated multi-modal sensor system consisting of sensors for sensing normal and shear force, distance, acceleration, temperature, and joint angles. The design is fully parametric, allowing automated scaling of the fingers to arbitrary dimensions in the human hand spectrum. To this end, the electronic parts are composed of interchangeable modules that facilitate the echanical scaling of the fingers and are fully enclosed by the mechanical parts of the finger. The resulting design model allows deriving freely scalable and multimodally sensorised fingers for robotic and prosthetic hands. Four physical demonstrators are assembled and tested to evaluate the approach

Artificial skin with sense of touch for robotic hand

This Master of Science thesis proposes a method to fabricate a soft robotic hand (SRH) with a sense of touch. Electronic skin (e-skin) – flexible and/or stretchable electronics that mimic the functions of human skin – is actively researched and developed for robotic applications (especially humanoid robots), owing to the high demand of robots that can safely interact with humans in the different industrial sectors. E-skin is also in demand for high-quality prosthetics that leverage the advances in brain-machine interfaces. The emphasis in this thesis is on the fabrication and characterization of an e-skin. The objective of this skin is to give an estimation of the amount of force exerted on it, which is beneficial for the SRH to feedback information about the manipulated object. We are aiming in this thesis to use fabrication approach of rapid prototyping to fulfill the following characteristics in SRH: actuation, soft touch, and sensation capabilities. Accordingly, we propose using 3D printing to fabricate both hand skeleton and molds to be used for artificial skin casting. Fingers are actuated by driving cables which are extended through inner channels embedded inside the hand skeleton. The specific goal of this thesis is to compare two different types of touch sensors for e-skin, one piezoresistive and one capacitive. The selected technologies are discussed in detail, and sensors based on these technologies are fabricated, characterized and analyzed comparatively. The results showed the potential of disclosing tactile information by implanting sensors in SRH. With comparing the piezoresistive sensor to the capacitive sensor, the latter exhibited a simpler approach for integration with the artificial skin to develop e-skin because it was feasible to fabricate the e-skin in one step instead of fabricating the artificial skin and the sensor separately. From the perspective of performance, capacitive sensor demonstrated higher efficiency in general compared to the piezoresistive sensor. As an example, the response in the piezore-sistive and capacitive sensor, showed linearity of 5.3% (on a logarithmic scale) 1.8% for both sensors, respectively. Moreover, the signal hysteresis in the capacitive sensor was better with a deviation of 2.7%, compared to 18.2% for the piezoresistive sensor. Finally, a SRH with integrated touch sensors is demonstrated. This paves the way for further research on utilizing the developed e-skin for objects recognition during hand gripping or designing a closed control loop system for dexterous control over the force of gripping. Moreover, an efficient artificial limb with sensation capabilities can be developed to feedback sensory information to the brain of the patient after being processed by a brain-machine interface

Synthetic and bio-artificial tactile sensing: a review

This paper reviews the state of the art of artificial tactile sensing, with a particular focus on bio-hybrid and fully-biological approaches. To this aim, the study of physiology of the human sense of touch and of the coding mechanisms of tactile information is a significant starting point, which is briefly explored in this review. Then, the progress towards the development of an artificial sense of touch are investigated. Artificial tactile sensing is analysed with respect to the possible approaches to fabricate the outer interface layer: synthetic skin versus bio-artificial skin. With particular respect to the synthetic skin approach, a brief overview is provided on various technologies and transduction principles that can be integrated beneath the skin layer. Then, the main focus moves to approaches characterized by the use of bio-artificial skin as an outer layer of the artificial sensory system. Within this design solution for the skin, bio-hybrid and fully-biological tactile sensing systems are thoroughly presented: while significant results have been reported for the development of tissue engineered skins, the development of mechanotransduction units and their integration is a recent trend that is still lagging behind, therefore requiring research efforts and investments. In the last part of the paper, application domains and perspectives of the reviewed tactile sensing technologies are discussed