Soft manipulators and grippers: A review

Soft robotics is a growing area of research which utilizes the compliance and adaptability of soft structures to develop highly adaptive robotics for soft interactions. One area in which soft robotics has the ability to make significant impact is in the development of soft grippers and manipulators. With an increased requirement for automation, robotics systems are required to perform task in unstructured and not well defined environments; conditions which conventional rigid robotics are not best suited. This requires a paradigm shift in the methods and materials used to develop robots such that they can adapt to and work safely in human environments. One solution to this is soft robotics, which enables soft interactions with the surroundings while maintaining the ability to apply significant force. This review paper assesses the current materials and methods, actuation methods and sensors which are used in the development of soft manipulators. The achievements and shortcomings of recent technology in these key areas are evaluated, and this paper concludes with a discussion on the potential impacts of soft manipulators on industry and society

Design Principles for Soft-Rigid Hybrid Manipulators

In nature, manipulators have evolved into different morphologies with varying rigidity to accomplish different tasks. Soft and continuum tentacles of the octopus, rigid and strong pincers of the crab and ligamentous jointed fingers of the human demonstrate the relationship between the complexity of a host’s task space and the design of its manipulator. Thus, the purpose of use a robotic manipulator should be considered as an important design parameter which governs the choice of appropriate materials and design rules. For tasks which require delicacy and strength at the same time, such as human-machine interaction, agriculture or robotic surgery hybrid soft-rigid manipulator designs should be investigated. Here, we present four design principles for building hybrid robot manipulators which incorporate soft and rigid materials and demonstrate each principle with working examples

Comparability of Raman Spectroscopic Configurations: A Large Scale Cross-Laboratory Study

This is the final version. Available on open access from the American Chemical Society via the DOI in this recordThe variable configuration of Raman spectroscopic platforms is one of the major obstacles in establishing Raman spectroscopy as a valuable physicochemical method within real-world scenarios such as clinical diagnostics. For such real world applications like diagnostic classification, the models should ideally be usable to predict data from different setups. Whether it is done by training a rugged model with data from many setups or by a primary-replica strategy where models are developed on a 'primary' setup and the test data are generated on 'replicate' setups, this is only possible if the Raman spectra from different setups are consistent, reproducible, and comparable. However, Raman spectra can be highly sensitive to the measurement conditions, and they change from setup to setup even if the same samples are measured. Although increasingly recognized as an issue, the dependence of the Raman spectra on the instrumental configuration is far from being fully understood and great effort is needed to address the resulting spectral variations and to correct for them. To make the severity of the situation clear, we present a round robin experiment investigating the comparability of 35 Raman spectroscopic devices with different configurations in 15 institutes within seven European countries from the COST (European Cooperation in Science and Technology) action Raman4clinics. The experiment was developed in a fashion that allows various instrumental configurations ranging from highly confocal setups to fibre-optic based systems with different excitation wavelengths. We illustrate the spectral variations caused by the instrumental configurations from the perspectives of peak shifts, intensity variations, peak widths, and noise levels. We conclude this contribution with recommendations that may help to improve the inter-laboratory studies.COST (European Cooperation in Science and Technology)Portuguese Foundation for Science and TechnologyNational Research Fund of Luxembourg (FNR)China Scholarship Council (CSC)BOKU Core Facilities Multiscale ImagingDeutsche Forschungsgemeinschaft (DFG, German Research Foundation

Free-space locomotion with thread formation

The paper presents a new concept of locomotion for wheeled or legged robots through an object-free space. The concept is inspired by the behaviour of spiders forming silk threads to move in 3D space. The approach provides the possibility of variation in thread diameter by deforming source material, therefore it is useful for a wider coverage of payload by mobile robots. As a case study, we propose a technology for descending locomotion through a free space with inverted formation of threads in variable diameters. Inverted thread formation is enabled with source material thermoplastic adhesive (TPA) through thermally-induced phase transition. To demonstrate the feasibility of the technology, we have designed and prototyped a 300-gram wheeled robot that can supply and deform TPA into a thread and descend with the thread from an existing hanging structure. Experiment results suggest repeatable inverted thread formation with a diameter range of 1.1-4.5 mm, and a locomotion speed of 0.73 cm per minute with a power consumption of 2.5 W. © 2013 IEEE

A biologically inspired soft robotic hand using chopsticks for grasping tasks

In this paper we investigate the dexterity of human manipulation capabilities by using a soft robotic hand. We built a robotic hand based on our inspiration from the real human’s, which is capable of handling chopsticks for grasping variations of objects. The robotic hand is made of soft structures, by using anthropomorphic configurations of bones, joints, ligaments, and tendons, that are connected to a minimum set of motor components, i.e. only four servomotors. By developing a minimalistic physics model of chopstick handling and its simulation experiments, we have identified one of the necessary conditions of actuation which enables the robot to grasp variations of small objects, those with different shape, size and weight

A dragline-forming mobile robot inspired by spiders

Mobility of wheeled or legged machines can be significantly increased if they are able to move from a solid surface into a three-dimensional space. Although that may be achieved by addition of flying mechanisms, the payload fraction will be the limiting factor in such hybrid mobile machines for many applications. Inspired by spiders producing draglines to assist locomotion, the paper proposes an alternative mobile technology where a robot achieves locomotion from a solid surface into a free space. The technology resembles the dragline production pathway in spiders to a technically feasible degree and enables robots to move with thermoplastic spinning of draglines. As an implementation, a mobile robot has been prototyped with thermoplastic adhesives as source material of the draglines. Experimental results show that a dragline diameter range of 1.17-5.27 mm was achievable by the 185 g mobile robot in descending locomotion from the solid surface of a hanging structure with a power consumption of 4.8 W and an average speed of 5.13 cm min-1. With an open-loop controller consisting of sequences of discrete events, the robot has demonstrated repeatable dragline formation with a relative deviation within -4% and a length close to the metre scale. © 2014 IOP Publishing Ltd

Motion pattern discrimination for soft robots with morphologically flexible sensors

Robots composed of soft materials can achieve high deformability and conformity with unstructured and dynamic environments due to their body mechanics. However, it is challenging to gather desirable information about these robots' behaviors as conventional sensory systems are not designed to detect infinite degrees of freedom on continuum bodies. This paper presents a technical method to sensorize a soft elastic body by using conductive thermoplastic elastomer (CTPE) based strain gauge sensors. Due to its thermoplastic nature, CTPE based sensors can be fabricated in flexible sizes and shapes and integrated into the soft elastic bodies. We analyze soft elastic deformations and extract strain vectors to find finite unique regions on continuum surfaces. Then we use these regions to design the morphologies of our fiber shaped CTPE sensors to discriminate soft robotic behaviors. To demonstrate our approach and show how the programmable sensor morphologies discriminate different motion patterns, we have built a soft elastic prismatic silicone (E = 1.31MPa) block and designed two sensors to discriminate serpentine and twisting patterns

Soft Robotics Education

Robotics education poses a significant challenge because it involves a number of different technological components and disciplines. So far, most of the existing teaching approaches focus on robots with fixed morphologies and rigid structures, which cover only subsets of the entire spectrum of related knowledge. From this perspective, this article explores an application of soft robotics research for robotics education and discusses the challenges and perspectives. We argue that the use of soft materials is crucial for understanding and teaching of a variety of topics related to intelligent adaptive systems. Along with the conceptual discussion, we introduce how the concept can be implemented into practical educational programs and report the latest concrete achievements in our lecture series

Modelling of continuous dragline formation in a mobile robot

A dragline-forming technology has been previously proposed to enable locomotion through an open-space where no solid surfaces present. The technology is intended for situations where payload requirements are unanticipated. In those situations, variability in dragline's diameter can minimize the use of material hence increase self-sufficiency of the robot. In a previous study, a robot was designed, prototyped and proven to be able to descend through an open-space by forming a thermoplastic dragline with a diameter range of 1.1-4.5 mm. However, the speed of locomotion was rather low due to the lack of an adequate control method for thermoplastic dragline formation. In this paper, models of mass flow and thermodynamics along dragline formation pathway are presented. The models are validated in a newly prototyped robot which forms a dragline continuously. Experiment results show that, when compared to the previous prototype and control method which consists of repeated sequences of discrete events, the speed of descending locomotion is significantly increased and reaches 12.0 cm/min