A Modular Soft Robotic Wrist for Underwater Manipulation (original) (raw)
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Scientific Reports
Modern marine biologists seeking to study or interact with deep-sea organisms are confronted with few options beyond industrial robotic arms, claws, and suction samplers. This limits biological interactions to a subset of "rugged" and mostly immotile fauna. As the deep sea is one of the most biologically diverse and least studied ecosystems on the planet, there is much room for innovation in facilitating delicate interactions with a multitude of organisms. The biodiversity and physiology of shallow marine systems, such as coral reefs, are common study targets due to the easier nature of access; SCUBA diving allows for in situ delicate human interactions. Beyond the range of technical SCUBA (~150 m), the ability to achieve the same level of human dexterity using robotic systems becomes critically important. The deep ocean is navigated primarily by manned submersibles or remotely operated vehicles, which currently offer few options for delicate manipulation. Here we present results in developing a soft robotic manipulator for deep-sea biological sampling. This low-power glove-controlled soft robot was designed with the future marine biologist in mind, where science can be conducted at a comparable or better means than via a human diver and at depths well beyond the limits of SCUBA. The technology relies on compliant materials that are matched with the soft and fragile nature of marine organisms, and uses seawater as the working fluid. Actuators are driven by a custom proportional-control hydraulic engine that requires less than 50 W of electrical power, making it suitable for battery-powered operation. A wearable glove master allows for intuitive control of the arm. The manipulator system has been successfully operated in depths exceeding 2300 m (3500 psi) and has been field-tested onboard a manned submersible and unmanned remotely operated vehicles. The design, development, testing, and field trials of the soft manipulator is placed in context with existing systems and we offer suggestions for future work based on these findings.
Robotics
Several bio-inspired underwater robots have been demonstrated in the last few years that can horizontally swim using different smart actuators. However, very few works have been presented on robots which can swim vertically, have a payload and resemble a jellyfish-like creature. In this work, we present the design, fabrication, and performance characterization of a new tethered robotic jellyfish, which is based on inflatable soft pneumatic composite (SPC) actuators. These soft actuators use compressed air to expand and contract, which help the robot to swim vertically in water. The soft actuators consist of elastomeric air chambers and very thin steel springs, which contribute to gaining faster motion of the biomimetic robot. A prototype of 220 mm in diameter and consisting of eight actuating units was fabricated and tested underwater in a fish tank. It reached a height of 400 mm within 2.5 s while carrying a dead weight of 100 g when tested at 70 psi (483 kPa) pressure. This high p...
IEEE Robotics & Automation Magazine, 2018
Ieee rObOTIcS & AUTOmATION mAGAZINe • 1070-9932/18©2018Ieee C urrent underwater end-effector technology has limits in terms of finesse and versatility. Because of this, the execution of several underwater operations, such as archeological recovery and biological sampling, often still requires direct intervention by human operators, exposing them to the risks of working in a difficult environment. This article proposes the design and implementation of an underactuated and compliant underwater end effector that embodies grasp capabilities comparable to those of a scuba's real hand as well as the large grasping envelope of grippers. The proposed end effector (Figure 1), with a design based on the Pisa/IIT SoftHand, is composed of a watertight modular chamber with pressure compensation-hosting the electronics and motor-and of a set of two soft terminal devices that implement an adaptive grasping function, one with an anthropomorphic hand form and one with a gripper-like form for medium/small and large object manipulation, respectively. These devices have been tested in a laboratory to withstand a pressure of 50 bar without damage or degradation in performance and are readily interchangeable through a custom fast tool change system. The two parts are connected via a magnetic drive coupling to transfer actuator torque to the wet fingers. Field results, obtained with the end effector controlled underwater by a human operator (10-m depth), show good grasping performance in terms of both dexterity and force tasks. Moreover, preliminary laboratory testing shows the possibility of implementing basic yet meaningful intrinsic force sensing for the reconstruction of fundamental grasp interactions.
Underwater Soft Robotics: A Review of Bioinspiration in Design, Actuation, Modeling, and Control
Micromachines, 2022
Nature and biological creatures are some of the main sources of inspiration for humans. Engineers have aspired to emulate these natural systems. As rigid systems become increasingly limited in their capabilities to perform complex tasks and adapt to their environment like living creatures, the need for soft systems has become more prominent due to the similar complex, compliant, and flexible characteristics they share with intelligent natural systems. This review provides an overview of the recent developments in the soft robotics field, with a focus on the underwater application frontier.
Bioinspired design and fabrication principles of reliable fluidic soft actuation modules
2015 IEEE International Conference on Robotics and Biomimetics (ROBIO), 2015
A large percentage of the field of robotics is devoted to catching up to what nature can already do. Taking inspiration from the snake and the jumping spider, we describe advances towards standardized modular multi-material composite soft pneumatic actuator design and fabrication. Previous pneumatic bi-directional bending actuators used in our soft robotic snake suffered from repeatability challenges and were prone to bursting in the seams. Here, we present a standardized fabrication method of soft pneumatic actuators to reduce the seams and incorporate a more reliable port for the input pressure. In addition, we explore the integration of our flexible curvature sensor, allowing for less invasive proprioceptive sensing of the actuator state. Finally, taking inspiration from jumping spider legs we also propose a plastic exoskeleton system, which can guide soft actuators to form complex shapes when pressurized. We show that all of these actuators were consistent and reliable over numerous trials. The next step is to combine these individual actuators into their respective bioinspired robotic systems: a soft modular snake and a soft jumping spider.
Body-Powered and Portable Soft Hydraulic Actuators as Prosthetic Hands
Robotics
Soft robotic actuators are highly flexible, compliant, dexterous, and lightweight alternatives that can potentially replace conventional rigid actuators in various human-centric applications. This research aims to develop a soft robotic actuator that leverages body movements to mimic the function of human fingers for gripping and grasping tasks. Unlike the predominantly used chamber-based actuation, this study utilizes actuators made from elastomers embedded with fiber braiding. The Young’s modulus of the elastomer and braiding angles of the fiber highly influenced the bending angle and force generated by these actuators. In this experiment, the bending and force profiles of these actuators were characterized by varying the combinations of elastomeric materials and braiding angles to suit hand manipulation tasks. Additionally, we found that utilizing water, which is relatively more incompressible than air, as the actuation fluid enabled easier actuation of the actuators using body m...
International Journal of Intelligent Robotics and Applications, 2022
Underwater exploration or inspection requires suitable robotic systems capable of maneuvering, manipulating objects, and operating untethered in complex environmental conditions. Traditional robots have been used to perform many tasks underwater. However, they have limited degrees of freedom, manipulation capabilities, portability, and have disruptive interactions with aquatic life. Research in soft robotics seeks to incorporate ideas of the natural flexibility and agility of aquatic species into man-made technologies to improve the current capabilities of robots using biomimetics. In this paper, we present a novel design, fabrication, and testing results of an underwater robot known as Kraken that has tentacles to mimic the arm movement of an octopus. To control the arm motion, Kraken utilizes a hybrid actuation technology consisting of stepper motors and twisted and a coiled fishing line polymer muscle (TCPFL). TCPs are becoming one of the promising actuation technologies due to their high actuation stroke, high force, light weight, and low cost. We have studied different arm stiffness configurations of the tentacles tailored to operate in different modalities (curling, twisting, and bending), to control the shape of the tentacles and grasp irregular objects delicately. Kraken uses an onboard battery, a wireless programmable joystick, a buoyancy system for depth control, all housed in a three-layer 3D printed dome-like structure. Here, we present Kraken fully functioning underwater in an Olympic-size swimming pool using its servo actuated tentacles and other test results on the TCPFL actuated tentacles in a laboratory setting. This is the first time that an embedded TCPFL actuator within elastomer has been proposed for the tentacles of an octopus-like robot along with the performance of the structures. Further, as a case study, we showed the functionality of the robot in grasping objects underwater for field robotics applications.
Development of the functional unit of a completely soft octopus-like robotic arm
2012 4th IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics (BioRob), 2012
In the presented paper the realization of an artificial functional unit of muscular hydrostat inspired by the octopus is shown. The octopus has been chosen because it shows high manipulation capabilities and dexterity without a skeletal support, thus it is a good example of Embodied Intelligence. Inspiration from Nature concerns the features that are interesting from a robotic point of view for the development of an artificial muscular hydrostat: in particular actuators arrangement and their antagonistic mechanism. The main focus was on the two key elements of the unit: soft actuators and support structure. Shape memory alloys (SMA) has been chosen for actuation technology, whereas the support structure is a braided sleeve, that provides spatial continuity to the action of the actuators. Two contiguous units have been built and tested in water. Capabilities of shortening, elongation and bending have been observed and their performances evaluated. A maximum elongation of 43% has been recorded from shortened to elongated condition, with a diameter variation of 25%, finding a good match with the expected results from the support structure models. Relative angle between extremities has been measured during bending in two conditions and their efficiency has been compared.
Two-chambers soft actuator bending and rotational properties for underwater application
Indonesian Journal of Electrical Engineering and Computer Science, 2019
This paper presents a study on bending and rotational properties of two-chambers soft actuator for underwater application. Previous study demonstrated the actuator characteristics required to optimize the bending performance and its potential to perform underwater because of the actuator material. However, there is less study of the actuator performance underwater as well as how the actuator tips rotating during actuator bending motion. In this paper, three tests have been proposed which are comparisons of bending angle simulation and experiment in air environment, bending angle performance in air and underwater environment as well as rotational angle of actuator tip in air environment. The bending angle of soft actuator is measured based on displacement in horizontal and vertical axis and for rotational angle, gyro sensor has been used. Based on the analysis, it is proven that the fabricated soft actuator performs almost similar trend to the simulation. It is also demonstrated that...