Toward Perceptive Soft Robots: Progress and Challenges (original) (raw)
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Towards creating a flexible shape sensor for soft robots
2018 IEEE International Conference on Soft Robotics (RoboSoft), 2018
Recent advances in robotics have witnessed an increasing transition from designing conventional robots with rigid components to partially or completely soft ones. Soft robots are known to be highly deformable and stretchable which makes the process of registering their shape and orientation in 3D challenging. This paper presents a first step of creating a flexible shape sensor for soft robots and a calibration algorithm that can compensate for different planar deflection conditions. In this paper, we describe the design and fabrication of the proposed shape sensor prototype utilizing three segmented optical fibers along the length of a flexible continuum arm. Three experimental scenarios of deflection are investigated to validate the relation between a mechanical deflection of the prototype and the change in intensity of the optical fibers' tip outputs (15 degrees deflection to the right and left, and planar double-bending). Camera images of the intensity circles without bending are used as a reference to relate the images features (location, angles, size, and intensity) to other bending cases. This study demonstrates the potential of relating the deflection status of a soft sensor to the image samples collected through a camera for the purpose of reconstructing and calibrating the shape sensor in 2D-space using MATLAB image processing toolbox and machine learning.
Advanced Intelligent Systems, 2021
Unlike conventional robots, soft robots are mostly inspired by biological systems and try to imitate the intrinsic softness, flexibility, and adaptability that conventional robots cannot achieve without direct control of motor function. [1] In conventional robots, the components, such as motors, sensors, rigid links, and controllers, are usually easily stacked. Soft robotics, instead, imitates biological structures in which sensing, control, and actuation are fully integrated and distributed in a soft body. [2-4] In addition, a soft and flexible body enables the robot to be lighter, adaptable, and operatable in humaninhabited environments, where both robustness and reliability ensure compliance and safety. [5,6] This approach to robotics has created a series of novel soft mobile platforms, manipulators, and other structures that perform increasingly complex tasks, such as locomotion on uneven terrain, manipulating objects of known and unknown shapes, wearable robotics-all benefitting from the intrinsic property of a soft robotic system. [7-10] There are several actuation principles behind these goals, which span from pressure-driven [11-13] and tendon-driven [14,15] to various stimulus responses (e.g., humidity, temperature, light). [16-19] Of these, pneumatic-driven, soft, muscle-like actuators exploit the effects of multiple mechanical deformations to generate controlled motion. [20-22] To better understand the actuation of soft deformations and the related robotic behavior, embedded sensing plays a major role in controlling the current configuration and enabling a live interaction with the environment. An inherently compliant system thus needs to be able to sense whether the deformation is self-induced through actuation or a consequence of an external stimulus. Using such information, a soft actuator can detect changes in the environment and adapt to them by modifying its configuration, [23] behavior, [24] and the force applied. [25] However, in most cases, this information is provided by external sensing units, such as cameras or motion trackers. [26] Some elastomeric-based actuators have also demonstrated both exteroception and proprioception through embedded strain and pressure sensors, [27,28] enabling them to sense and respond to external forces. [29-33]
Advanced Engineering Materials, 2017
The emerging field of soft robotics makes use of many classes of materials including metals, low glass transition temperature (Tg) plastics, and high Tg elastomers. Dependent on the specific design, all of these materials may result in extrinsically soft robots. Organic elastomers, however, have elastic moduli ranging from tens of megapascals down to kilopascals; robots composed of such materials are intrinsically soft − they are always compliant independent of their shape. This class of soft machines has been used to reduce control complexity and manufacturing cost of robots, while enabling sophisticated and novel functionalities often in direct contact with humans. This review focuses on a particular type of intrinsically soft, elastomeric robot − those powered via fluidic pressurization.
Design Considerations for 3D Printed, Soft, Multimaterial Resistive Sensors for Soft Robotics
Frontiers in Robotics and AI, 2019
Sensor design for soft robots is a challenging problem because of the wide range of design parameters (e.g., geometry, material, actuation type, etc.) critical to their function. While conventional rigid sensors work effectively for soft robotics in specific situations, sensors that are directly integrated into the bodies of soft robots could help improve both their exteroceptive and interoceptive capabilities. To address this challenge, we designed sensors that can be co-fabricated with soft robot bodies using commercial 3D printers, without additional modification. We describe an approach to the design and fabrication of compliant, resistive soft sensors using a Connex3 Objet350 multimaterial printer and investigated an analytical comparison to sensors of similar geometries. The sensors consist of layers of commercial photopolymers with varying conductivities. We characterized the conductivity of TangoPlus, TangoBlackPlus, VeroClear, and Support705 materials under various conditions and demonstrate applications in which we can take advantage of these embedded sensors.
A Survey on Actuators, Sensors and Control Mechanism Used in Soft Robotics
A proposed adaptive soft orthotic device performs motion sensing and production of assistive forces with a modular, pneumatically-driven, hyper-elastic composite. Wrapping the material around a joint will allow simultaneous motion sensing and active force response through shape and rigidity control. This monolithic elastomer sheet contains a series of miniaturized pneumatically-powered McKibben-type actuators that exert tension and enable adaptive rigidity control. The elastomer is embedded with conductive liquid channels that detect strain and bending deformations induced by the pneumatic actuators. In addition, the proposed system is modular and can be configured for a diverse range of motor tasks, joints, and human subjects. This modular functionality is accomplished with a decentralized network of self-configuring nodes that manage the collection of sensory data and the delivery of actuator feedback commands. This paper mainly describes the design of the soft orthotic device as well as actuator and sensor components. The characterization of the individual sensors, actuators, and the integrated device is also presented.
Soft Robotics: Challenges and Perspectives
Procedia Computer Science, 2011
There has been an increasing interest in the use of unconventional materials and morphologies in robotic systems because the underlying mechanical properties (such as body shapes, elasticity, viscosity, softness, density and stickiness) are crucial research topics for our in-depth understanding of embodied intelligence. The detailed investigations of physical system-environment interactions are particularly important for systematic development of technologies and theories of emergent adaptive behaviors. Based on the presentations and discussion in the Future Emerging Technology (fet11) conference, this article introduces the recent technological development in the field of soft robotics, and speculates about the implications and challenges in the robotics and embodied intelligence research. © Selection and peer-review under responsibility of FET11 conference organizers and published by Elsevier B.V.
Soft Robotics: New Perspectives for Robot Bodyware and Control
Frontiers in bioengineering and biotechnology, 2014
The remarkable advances of robotics in the last 50 years, which represent an incredible wealth of knowledge, are based on the fundamental assumption that robots are chains of rigid links. The use of soft materials in robotics, driven not only by new scientific paradigms (biomimetics, morphological computation, and others), but also by many applications (biomedical, service, rescue robots, and many more), is going to overcome these basic assumptions and makes the well-known theories and techniques poorly applicable, opening new perspectives for robot design and control. The current examples of soft robots represent a variety of solutions for actuation and control. Though very first steps, they have the potential for a radical technological change. Soft robotics is not just a new direction of technological development, but a novel approach to robotics, unhinging its fundamentals, with the potential to produce a new generation of robots, in the support of humans in our natural environm...
Bio-inspired soft robotics: Material selection, actuation, and design
Extreme Mechanics Letters
Animals exploit the deformability of soft structures to move efficiently in complex natural environments. These soft structures are inherently compliant and enable large strains in components not typically found in robotics. Such capabilities have inspired robotic engineers to incorporate soft technologies into their designs. One goal in soft robotics is to endow robots with new, bioinspired features that permit morphologically adaptive interactions with unpredictable environments. Here, we review three key elements of bioinspired soft robots from a mechanics vantage point, namely, materials selection, actuation, and design. Soft materials are necessary for safe interaction and overall actuation of bioinspired robots. The intrinsic properties of materials in soft robots allow for an ''embodied intelligence'' that can potentially reduce the mechanical and algorithmic complexity in ways not possible with rigidbodied robots Finally, soft robotics can be combined with tissue engineering and synthetic biology to create bio-hybrid systems with unique sensing, dynamic response, and mobility. Bioinspired soft robots have the ability to also expedite the evolution of co-robots that can safely interact with humans.
Integrated soft bending sensor for soft robotic manipulators
Soft, flexible robotic manipulators offer many advantages to Minimally Invasive Surgery (MIS) compared to using conventional rigid laparoscopic instruments: Soft robots are inherently safe due to the material used for the body structure and their compliant actuation system allowing safe interaction with its soft environment; the flexibility allows bending around organs and navigating along trajectories within the complex anatomical environment. To feedback the tip position of these manipulators required for position control for instance, it is beneficial to integrate a bending sensor that accurately determines the curvature. This paper presents a bending sensor embedded into a pneumatically actuated, soft manipulator based on a silicone body structure. The sensing system is made of three threads of stretchable electro-conductive yarn inserted in the periphery for direct measurement of the actuation chamber lengths. The bending sensor is able to measure elongation and bending behaviour. The soft structure of the manipulator is maintained. Our sensor is benchmarked using a commercially available magnetic tracking system.
ArXiv, 2019
Traditional robots have rigid links and structures that limit their ability to interact with the dynamics of their immediate environment. For example, conventional robot manipulators with rigid links can only manipulate objects using specific end effectors. These robots often encounter difficulties operating in unstructured and highly congested environments. A variety of biological organisms exhibit complex movement with soft structures devoid of rigid components. Inspired by biology, researchers have been able to design and build soft robots. With a soft structure and redundant degrees of freedom, these robots can be used for delicate tasks in unstructured environments. This review discusses the motivation for soft robots, their design processes as well as their applications and limitations. Soft robots have the ability to operate in unstructured environment due to their inherent potential to exploit morphological computation to adapt to, and interact with, the world in a way that ...