Fluid-based soft actuators are an attractive option for lightweight and human-safe robots. These actuators, combined with fluid pressure force feedback, are in principle a form of series-elastic actuation (SEA), in which nearly all driving-point (e.g. motor/gearbox) friction can be eliminated. Fiber-elastomer soft actuators offer unique low-friction and low-hysteresis mechanical properties which are particularly suited to force-control based on internal pressure force feedback, rather than traditional external force feedback using force/tactile sensing, since discontinuous (Coulomb) endpoint friction is unobservable to internal fluid pressure. However, compensation of endpoint smooth hysteresis through a model-based feedforward term is possible. We report on internal-pressure force feedback through a disturbance observer (DOB) and model-based feedforward compensation of endpoint friction and nonlinear hysteresis for a 2-DOF lightweight robotic gripper driven by rolling-diaphragm linear actuators coupled to direct-drive brushless motors, achieving an active low-frequency endpoint impedance range ("Z-width") of 50dB.
Worcester Polytechnic Institute（伍斯特理工学院）；NVIDIA（英伟达）；University of Copenhagen（哥本哈根大学）
In this work we present a framework that is capable of accurately representing soft robotic actuators in a multiphysics environment in real-time. We propose a constraint-based dynamics model of a 1-dimensional pneumatic soft actuator that accounts for internal pressure forces, as well as the effect of actuator latency and damping under inflation and deflation and demonstrate its accuracy a full soft robotic snake with the composition of multiple 1D actuators. We verify our model's accuracy in static deformation and dynamic locomotion open-loop control experiments. To achieve real-time performa…
Soft robots are promising for manipulation tasks thanks to their compliance, safety, and high degree of freedom. However, the commonly used bidirectional continuum segment design means soft robotic manipulators only function in a limited hemispherical workspace. This work increases a soft robotic arm's workspace by designing, fabricating, and controlling an additional soft prismatic actuator at the base of the soft arm. This actuator consists of pneumatic artificial muscles and a piston, making the actuator back-driveable. We increase the task space volume by 116\%, and we are now able to perf…
A Robotic Testing Platform for Pipelined Discovery of Resilient Soft Actuators
Department of Mechanical and Industrial Engineering, University of Toronto（多伦多大学机械与工业工程系）；Institute of Materials Science, University of Connecticut（康涅狄格大学材料科学研究所）；School of Mechanical, Aerospace, and Manufacturing Engineering, University of Connecticut（康涅狄格大学机械、航空航天与制造工程学院）；Material Science and Engineering, University of Connecticut（康涅狄格大学材料科学与工程系）；Inorganic Polymers Department, Petru Poni Institute of Macromolecular Chemistry（彼得·波尼宏分子化学研究所无机聚合物部门）
Japan Advanced Institute of Science and Technology（日本先端科学技术大学院大学）；Tokyo Institute of Technology（东京工业大学）
To increase the awareness and impact, soft robotics needs to go beyond the lab environment and should be readily accessible to those even with no robotic expertise. However, most prevailing manufacturing methodologies require either professional equipment or materials that are not usually available to common people, thereby constraining the accessibility of soft robotics. In this communication, we propose a lightweight and low-cost soft bending actuator, called BPActuator, that can be easily fabricated with plastics and balloons. We fabricated a range of actuators with various morphology for c…
This paper evaluates the capabilities of a soft robotic pneumatic actuator derived from the terrain display haptic device, "The Smart Shoe." The bladder design of the Smart Shoe is upgraded to include a pressure supply and greater output flow capabilities. A bench top setup is created to rigorously test this new type of actuator. The bandwidth and stiffness capability of this new actuator are evaluated relative to forces and displacements encountered during human gait. Four force vs. displacement profiles relevant to haptic terrain display are proposed and tested using sliding-mode tracking co…
Centre for Advanced Robotics（高级机器人中心）；School of Engineering and Materials Science（工程与材料科学学院）；Queen Mary University of London（伦敦玛丽女王大学）
Common disabilities like stroke and spinal cord injuries may cause loss of motor function in hands. They can be treated with robot assisted rehabilitation techniques, like continuously opening and closing the hand with help of a robot, in a cheaper, and less time consuming manner than traditional methods. Hand exoskeletons are developed to assist rehabilitation, but their bulky nature brings with it certain challenges. As soft robots use elastomeric and fabric elements rather than heavy links, and operate with pneumatic, hydraulic or tendon based rather than traditional rotary or linear motors…
Towards Soft Robotic Exogloves for Musculoskeletal Manipulation to Reduce Pain and Spasticity
Department of Mechanical Engineering, Stevens Institute of Technology（机械工程系，史蒂文斯理工学院）；Faculty of Mechanical Engineering, Stevens Institute of Technology（机械工程学院，史蒂文斯理工学院）
EquiMus: Energy-Equivalent Dynamic Modeling and Simulation of Musculoskeletal Robots Driven by Linear Elastic Actuators
Department of Mechanical Engineering, State Key Laboratory of Tribology in Advanced Equipment, Beijing Key Laboratory of Transformative High-end Manufacturing Equipment and Technology（机械工程系、摩擦学国家重点实验室、北京 transformative 高端制造装备与技术重点实验室）
University laboratories deliver unique hands-on experimentation for STEM students but often lack state-of-the-art equipment and provide limited access to their equipment. The University of Texas Cloud Laboratory provides remote access to a cutting-edge series elastic actuators for student experimentation regarding human-centered robotics, dynamical systems, and controls. Through a browser-based interface, students are provided with various learning materials using the remote hardware-in-the-loop system for effective experiment-based education. This paper discusses the methods used to connect r…
University of Arkansas（阿肯色大学）；Vanderbilt University（范德堡大学）；DePaul University（德保罗大学）
Soft robotics have gained increased attention from the robotic community due to their unique features such as compliance and human safety. Impressive amount of soft robotic prototypes have shown their superior performance over their rigid counter parts in healthcare, rehabilitation, and search and rescue applications. However, soft robots are yet to capitalize on their potential outside laboratories and this could be attributed to lack of advanced sensing capabilities and real-time dynamic models. In this pilot study, we explore the use of high-accuracy, high-bandwidth deformation sensing via …
Reconfigurable, Transformable Soft Pneumatic Actuator with Tunable 3D Deformations for Dexterous Soft Robotics Applications
Hong Kong University of Science and Technology (HKUST)（香港科技大学）；HKUST Shenzhen-Hong Kong Collaborative Innovation Research Institute（香港科技大学深圳-香港协同创新研究院）
We present a self-contained, soft robotic hand composed of soft pneumatic actuator modules that are equipped with strain and pressure sensing. We show how this data can be used to discern whether a grasp was successful. Co-locating sensing and embedded computation with the actuators greatly simplifies control and system integration. Equipped with a small pump, the hand is self-contained and needs only power and data supplied by a single USB connection to a PC. We demonstrate its function by grasping a variety of objects ranging from very small to large and heavy objects weighing more than the …
National University of Singapore (NUS)（新加坡国立大学）；Advanced Robotics Center (ARC) at NUS（新加坡国立大学先进机器人中心）
The shoulder is responsible for the movement of the entire upper limb. It is capable of articulating in three degrees-of-freedom (DOF), enabling the arm to perform manipulation actions with incomparable dexterity. Exoskeletons targeting the shoulder must be able to emulate its complex kinematics. While typical architectures have proven to be useful, they employ complex and usually inadequate techniques to match the mobility of the shoulder. A new 2-DOF soft robotic shoulder exoskeleton is presented. Modular soft robotic actuators with separated inflation modules on the exoskeleton are able to …
This study is part of research aiming at increasing the range of dynamic tasks for teleoperated field robotics in order to allow operators to use the full range of human motions without being limited by the dynamics of the robotic manipulator. A new variable impedance actuator (VIA) was designed, capable of reproducing motions through teleoperation from precise positioning tasks to highly dynamic tasks. The design requirements based on previous human user studies were a stiffness changing time of 50 ms, a peak output velocity of 20 rad/s and variable damping allowing to suppress undesired osci…
New York University（纽约大学）；Sapienza University of Rome（罗马第一大学）
Soft actuators have attracted a great deal of interest in the context of rehabilitative and assistive robots for increasing safety and lowering costs as compared to rigid-body robotic systems. During actuation, soft actuators experience high levels of deformation, which can lead to microscale fractures in their elastomeric structure, which fatigues the system over time and eventually leads to macroscale damages and eventually failure. This paper reports finite element modeling (FEM) of pneu-nets at high angles, along with repetitive experimentation at high deformation rates, in order to study …
Compared to traditional rigid robotics, soft robotics has attracted increasing attention due to its advantages as compliance, safety, and low cost. As an essential part of soft robotics, the soft robotic gripper also shows its superior while grasping the objects with irregular shapes. Recent research has been conducted to improve its grasping performance by adjusting the variable effective length (VEL). However, the VEL achieved by multi-chamber design or tunable stiffness shape memory material requires complex pneumatic circuit design or a time-consuming phase-changing process. This work prop…
Successful soft robot modeling approaches appearing in recent literature have been based on a variety of distinct theories, including traditional robotic theory, continuum mechanics, and machine learning. Though specific modeling techniques have been developed for and validated against already realized systems, their strengths and weaknesses have not been explicitly compared against each other. In this paper, we show how three distinct model structures ---a lumped-parameter model, a continuum mechanical model, and a neural network--- compare in capturing the gross trends and specific features …
This paper discusses and contests the claims of ``Soft Pneumatic Actuator Fascicles for High Force and Reliability'' a research article which was originally published in the March 2017 issue of the Journal Soft Robotics. The original paper claims that the summed forces of multiple thin-walled extending McKibben muscles are greater than a volumetrically equivalent actuator of the same length at the same pressure. The original paper also claims that the purported benefit becomes more pronounced as the number of smaller actuators is increased. Using reasonable assumptions, the analysis of this pa…
Roboticists have been seeking to address this situation in recent years through the use of soft robots. Unfortunately, identifying appropriate models for the complete analysis and investigation of soft robots for design and control purposes can be problematic. This paper seeks to address this challenge by proposing two complementary modeling techniques for a particular type of soft robotic actuator known as a Fiber-Reinforced Elastomeric Enclosure (FREE). We propose that researchers can leverage multiple models to fill gaps in the understanding of the behavior of soft robots. We present and ev…
This paper presents preliminary results of the design, development, and evaluation of a hand rehabilitation glove fabricated using lobster-inspired hybrid design with rigid and soft components for actuation. Inspired by the bending abdomen of lobsters, hybrid actuators are built with serially jointed rigid shells actuated by pressurized soft chambers inside to generate bending motions. Such bio-inspiration absorbs features from the classical rigid-bodied robotics with precisely-defined motion generation, as well as the emerging soft robotics with light-weight, physically safe, and adaptive act…
University of California, Santa Barbara（加州大学圣巴巴拉分校）；University of New South Wales（新南威尔士大学）
Conformable robotic systems are attractive for applications in which they can be used to actuate structures with large surface areas, to provide forces through wearable garments, or to realize autonomous robotic systems. We present a new family of soft actuators that we refer to as Fluidic Fabric Muscle Sheets (FFMS). They are composite fabric structures that integrate fluidic transmissions based on arrays of elastic tubes. These sheet-like actuators can strain, squeeze, bend, and conform to hard or soft objects of arbitrary shapes or sizes, including the human body. We show how to design and …
Design, Dynamic Modeling and Control of a 2-DOF Robotic Wrist Actuated by Twisted and Coiled Actuators
College of Advanced Manufacturing and Robotics（先进制造与机器人学院）；State Key Laboratory of Turbulence and Complex Systems（湍流与复杂系统国家重点实验室）；Peking University（北京大学）；Department of Electrical and Computer Engineering（电气与计算机工程系）
Magnetic Tactile-Driven Soft Actuator for Intelligent Grasping and Firmness Evaluation
Soft BioRobotics Perception Lab, Istituto Italiano di Tecnologia (IIT)（软生物机器人感知实验室，意大利技术研究院）；The BioRobotics Institute, Scuola Superiore Sant’Anna (SSSA)（生物机器人研究所，圣安娜高等学院）；Department of Haptic Intelligence, CVTE Guangzhou Shiyuan Electronics Co., Ltd（触觉智能部门，广州世渊电子有限公司）；Università degli Studi di Genova (UniGe)（热那亚大学）
ETH Zurich（苏黎世联邦理工学院）；The University of Tokyo（东京大学）
Due to their inherent compliance, soft robots are more versatile than rigid linked robots when they interact with their environment, such as object manipulation or biomimetic motion, and considered the key element in introducing robots to everyday environments. Although various soft robotic actuators exist, past research has focused primarily on designing and analyzing single components. Limited effort has been made to combine each component to create an overall capable, integrated soft robot. Ideally, the behavior of such a robot can be accurately modeled, and its motion within an environment…
Literary Emotions in Motion: A Soft Robotics Installation for Tactile Storytelling
Department of Mechanical Engineering, University of Chile（智利大学机械工程系）；Independent Researcher（独立研究员）；Bolivian Catholic University（玻利维亚天主大学）；Institute of Engineering Sciences, University of O’Higgins（奥希金斯大学工程科学研究所）
University of Colorado（科罗拉多大学）；Materials Science and Engineering Program, University of Colorado（科罗拉多大学材料科学与工程项目）；Department of Electrical Engineering, University of Colorado（科罗拉多大学电气工程系）；Department of Computer Science, University of Colorado（科罗拉多大学计算机科学系）
Soft robotics is a field of robotic system design characterized by materials and structures that exhibit large-scale deformation, high compliance, and rich multifunctionality. The incorporation of soft and deformable structures endows soft robotic systems with the compliance and resiliency that makes them well-adapted for unstructured and dynamic environments. While actuation mechanisms for soft robots vary widely, soft electrostatic transducers such as dielectric elastomer actuators (DEAs) and hydraulically amplified self-healing electrostatic (HASEL) actuators have demonstrated promise due t…
An Ergonomic, Customizable Soft Robotic Glove toward Personalized Hand Rehabilitation
The Biorobotics Inst. and Dept. of Excellence in Robotics and AI, Scuola Superiore Sant’Anna, Pisa, Italy（生物机器人研究所和机器人与人工智能卓越部门，圣安娜高等学院，比萨，意大利）；Institute of Mechanical Intelligence and Department of Excellence in Robotics and AI, Scuola Superiore Sant’Anna (SSSA), 56127, Pisa, Italy（机械智能研究所和机器人与人工智能卓越部门，圣安娜高等学院（SSSA），56127，比萨，意大利）；CAS Key Laboratory of Mechanical Behavior and Design of Materials, Institute of Humanoid Robots, School of Engineering Sciences, University of Science and Technology of China, Hefei, China（中国科学技术大学材料机械行为与设计国家重点实验室，人形机器人研究所，工程科学学院，合肥，中国）；Modular Implantable Neuroprostheses (MINE) Laboratory, Università Vita-Salute San Raffaele & Sant’Anna School of Advanced Studies, Milan, Italy（可植入神经假体（MINE）实验室，维塔-桑瑞法大学及圣安娜高级研究学院，米兰，意大利）；Careggi University Hospital, 50134 Florence, Italy（Careggi大学医院，50134，佛罗伦萨，意大利）；Bertarelli Fndn. Chair in Translational Neuroengineering, Neuro X Institute, École Polytechnique Fédérale de Lausanne (EPFL), Laussane, Switzerland（伯特拉里基金会转化神经工程主席，Neuro X研究所，洛桑联邦理工学院（EPFL），洛桑，瑞士）
Beijing National Research Center for Information Science and Technology (BNRist)（北京信息科学与技术国家研究中心（BNRist））；State Key Lab on Intelligent Technology and Systems（智能技术与系统国家重点实验室）；Tsinghua University（清华大学）
Tactile sensing plays an important role in robotic perception and manipulation. To overcome the real-world limitations of data collection, simulating tactile response in virtual environment comes as a desire direction of robotic research. Most existing works model the tactile sensor as a rigid multi-body, which is incapable of reflecting the elastic property of the tactile sensor as well as characterizing the fine-grained physical interaction between two objects. In this paper, we propose Elastic Interaction of Particles (EIP), a novel framework for tactile emulation. At its core, EIP models t…
Realizing high-performance soft robotic grippers is challenging because of the inherent limitations of the soft actuators and artificial muscles that drive them, including low force output, small actuation range, and poor compactness. Despite advances in this area, realizing compact soft grippers with high dexterity and force output is still challenging. This paper explores twisted string actuators (TSAs) to drive a soft robotic gripper. TSAs have been used in numerous robotic applications, but their inclusion in soft robots has been limited. The proposed design of the gripper was inspired by …
University of Wollongong（伍伦贡大学）；National University of Singapore（新加坡国立大学）
This paper deals with the robust force and position control problems of Series Elastic Actuators. It is shown that a Series Elastic Actuator's force control problem can be described by a second-order dynamic model which suffers from only matched disturbances. However, the position control dynamics of a Series Elastic Actuator is of fourth-order and includes matched and mismatched disturbances. In other words, a Series Elastic Actuator's position control is more complicated than its force control, particularly when disturbances are considered. A novel robust motion controller is proposed for Se…
University of Illinois Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；Beckman Institute for Advanced Science and Technology（贝克曼高等科学技术研究所）；University of Michigan（密歇根大学）
Many soft-body organisms found in nature flourish underwater. Similarly, soft robots are potentially well-suited for underwater environments partly because the problematic effects of gravity, friction, and harmonic oscillations are less severe underwater. However, it remains a challenge to design, fabricate, waterproof, model, and control underwater soft robotic systems. Furthermore, submersible robots usually do not have configurable components because of the need for sealed electronics and mechanical elements. This work presents the development of a modular and submersible soft robotic arm d…
In this paper, we present an adjustable-equilibrium parallel elastic actuator (AE-PEA). The actuator consists of a motor, an equilibrium adjusting mechanism, and a spring arranged into a cylindrical geometry, similar to a motor-gearbox assembly. The novel component of the actuator is the equilibrium adjusting mechanism which (i) does not require external energy to maintain the equilibrium position of the actuator even if the spring is deformed and (ii) enables equilibrium position control with low energy cost by rotating the spring while keeping it undeformed. Adjustable equilibrium parallel e…
École Polytechnique Fédérale de Lausanne（洛桑联邦理工学院）
We present a fully edible pneumatic actuator based on gelatin-glycerol composite. The actuator is monolithic, fabricated via a molding process, and measures 90 mm in length, 20 mm in width, and 17 mm in thickness. Thanks to the composite mechanical characteristics similar to those of silicone elastomers, the actuator exhibits a bending angle of 170.3 ° and a blocked force of 0.34 N at the applied pressure of 25 kPa. These values are comparable to elastomer based pneumatic actuators. As a validation example, two actuators are integrated to form a gripper capable of handling various objects, hig…
