Soft robot actuators using energy-efficient valves controlled by electropermanent magnets

This paper presents the design, fabrication, and evaluation of a novel type of valve that uses an electropermanent magnet [1]. This valve is then used to build actuators for a soft robot. The developed EPM valves require only a brief (5 ms) pulse of current to turn flow on or off for an indefinite period of time. EPMvalves are characterized and demonstrated to be well suited for the control of elastomer fluidic actuators. The valves drive the pressurization and depressurization of fluidic channels within soft actuators. Furthermore, the forward locomotion of a soft, multi-actuator rolling robot is driven by EPM valves. The small size and energy-efficiency of EPM valves may make them valuable in soft mobile robot applications.United States. Defense Advanced Research Projects Agency (Grant W911NF-08-C-0060)United States. Defense Advanced Research Projects Agency (Grant W911NF-08-1-0228)Boeing Compan

The Milli-Motein: A self-folding chain of programmable matter with a one centimeter module pitch

The Milli-Motein (Millimeter-Scale Motorized Protein) is ca chain of programmable matter with a 1 cm pitch. It can fold itself into digitized approximations of arbitrary three-dimensional shapes. The small size of the Milli-Motein segments is enabled by the use of our new electropermanent wobble stepper motors, described in this paper, and by a highly integrated electronic and mechanical design. The chain is an interlocked series of connected motor rotors and stators, wrapped with a continuous flex circuit to provide communications, control, and power transmission capabilities. The Milli-Motein uses off-the-shelf electronic components and fasteners, and custom parts fabricated by conventional and electric discharge machining, assembled with screws, glue, and solder using tweezers under a microscope. We perform shape reconfiguration experiments using a four-segment Milli-Motein. It can switch from a straight line to a prescribed shape in 5 seconds, consuming 2.6 W power during reconfiguration. It can hold its shape indefinitely without power. During reconfiguration, a segment can lift the weight of one but not two segments as a horizontal cantilever.United States. Defense Advanced Research Projects Agency. Programmable Matter ProgramUnited States. Defense Advanced Research Projects Agency. Maximum Mobility and Manipulation (M3) ProgramUnited States. Army Research Office (Grant W911NF-08-1-0254)United States. Army Research Office (Grant W911NF-11-1-0096)Massachusetts Institute of Technology. Center for Bits and Atom

Electropermanent magnetic anchoring for surgery and endoscopy

The use of magnets for anchoring of instrumentation in minimally invasive surgery and endoscopy has become of increased interest in recent years. Permanent magnets have significant advantages over electromagnets for these applications; larger anchoring and retraction force for comparable size and volume without the need for any external power supply. However, permanent magnets represent a potential hazard in the operating field where inadvertent attraction to surgical instrumentation is often undesirable. The current work proposes an interesting hybrid approach which marries the high forces of permanent magnets with the control of electromagnetic technology including the ability to turn the magnet OFF when necessary. This is achieved through the use of an electropermanent magnet, which is designed for surgical retraction across the abdominal and gastric walls. Our electropermanent magnet, which is hand-held and does not require continuous power, is designed with a center lumen which may be used for trocar or needle insertion. The device in this application has been demonstrated successfully in the porcine model where coupling between an intraluminal ring magnet and our electropermanent magnet facilitated guided insertion of an 18 Fr Tuohy needle for guidewire placement. Subsequent investigations have demonstrated the ability to control the coupling distance of the system alleviating shortcomings with current methods of magnetic coupling due to variation in transabdominal wall thicknesses. With further refinement, the magnet may find application in the anchoring of endoscopic and surgical instrumentation for minimally invasive interventions in the gastrointestinal tract

Robotic Actuation and Control with Programmable, Field-Activated Material Systems

This dissertation presents novel, field-activated smart material systems for the actuation and control of autonomous robots. Smart materials, a type of material whose properties can be changed with an external stimuli, represent a promising direction to expand upon existing robotic control and actuation methods, particularly in the sub-fields of soft robotics and robotic grasping. Specifically, this work makes the following contributions: i) a literature review that synthesizes recent work on field-activated smart materials and their use in soft robotics; ii) an electrorheological fluid (ERF) valve to control soft actuators; iii) magnetic elastomers (MEs) to increase the grip strength of soft grippers; and iv) a low-power method for torque transmission enabled by magnetorheological fluid (MRF) and electropermanent magnet arrays. After the introduction, this dissertation presents a comprehensive literature review paper (Chapter 2) regarding the use of field-activated materials in soft robotics, with an emphasis on magnetic elastomers. The second paper (Chapter 3) describes the development of a 3D-printed pressure valve intended to leverage the pressuring-holding properties of ERF when under the influence of a high voltage field to actuate soft actuators. The third paper (Chapter 4) demonstrates how magnetic elastomers and magnetic fields can enhance soft robotic grip strength and versatility. The fourth paper (Chapter 5) models, fabricates, and characterizes a MRF-containing clutch device able to rapidly and reversibly module the amount of torque transmitted from an input shaft to an output by leveraging low-power electropermanent magnet arrays. Each work focuses on a field-activated smart material to perform a specific robotic function, with particular emphasis given to compliant mechanisms and soft robotics, as well as to reducing cost and improving ease of fabrication with the use of modern fabrication techniques. In these described papers, field-activated materials are first modeled and then deployed in functional prototypes, and their robotic utility is described in detail after extensive experimental characterization

非線形弾性要素による内部力補償に基づく無段階変位–力変換機構の創生 ― 微小操作力で強大な磁気力・把持力・制動力・張力を制御可能とするロボット要素 ―

Tohoku University博士（情報科学）thesi

Coordinated locomotion between robots separated by a surface

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 69-70).This SM thesis presents the design, modeling, and experimental verification of a novel, programmable connection mechanism for robots separated by a-surface. The connector uses electropermanent magnets (EPMs) [5] to establish a continuum of clamping force between the robots, enabling the motion of one robot to slave the other during a variety of maneuvers. The author designs a novel, solid-state EPM arrangement capable of generating up to an estimated 890N of clamping force under environmental load conditions. A relationship between geometric and environmental variables and connection assembly performance is first modeled and subsequently experimentally characterized. By implementing these connectors in a custom manufactured pair of assembly robots, the author demonstrates the connection assembly and magnetizing hardware can be compactly fit within a tetherless robot application. This mechanism provides a repeatable, easily-automated alternative to robotic systems that depend on mechanic means to regulate clamping force [6].by Andrew D. Marchese.S.M

Compliant Electric Actuators Based on Handed Shearing Auxetics

In this paper, we explore a new class of electric motor-driven compliant actuators based on handed shearing auxetic cylinders. This technique combines the benefits of compliant bodies from soft robotic actuators with the simplicity of direct coupling to electric motors. We demonstrate the effectiveness of this technique by creating linear actuators, a four degree-of-freedom robotic platform, and a soft robotic gripper. We compare the soft robotic gripper against a state of the art pneumatic soft gripper, finding similar grasping performance in a significantly smaller and more energy-efficient package.Boeing CompanyNational Science Foundation (U.S.) (grant numbers NSF IIS- 1226883)National Science Foundation (U.S.) (grant numbers NSF CCF-1138967

Novel pneumatic circuit for the computational control of soft robots

Soft robots are of significant research interest in recent decades due to their adaptability to unstructured environments and safe interaction with humans. Soft pneumatic robots, one of the most dominant subsets of soft robots, utilize the interaction between soft elastomeric materials and pressurized air to achieve desired functions. However, the systems currently used for signal computation and pneumatic regulation often make use of rigid valves, pumps, syringe drivers, microcontrollers et al. These bulky and non-integrable devices limit the performance of pneumatically-driven soft robots, carrying challenges for the robot to be miniaturized, untethered, and agile. This DPhil aims to develop pneumatic circuits that can be integrated into the soft robot bodies while performing both onboard computation and control. This thesis presents our contributions towards the aforementioned objective step by step. Firstly, we designed a 3D-printable bistable valve with tunable behaviours for controlling soft pneumatic robots. As an integrable control device, the valve stores one bit of binary information without requiring a constant energy supply and correspondingly controls a pneumatic chamber. Secondly, in order to reduce the number of valves required to control multi-chamber soft robots, we introduced a modular approach to design multi-channel bistable valves based on the previous work. Thirdly, in order to achieve continuous pressure modulation with integrable devices, we designed a soft proportional valve, utilizing the continuous deformation of Magnetorheological Elastomer (MRE) under magnetic flux. Apart from the analogue activation manner, this design also ensures a fast response time, operating at a time scale of tens of milliseconds, much shorter than the mechanical response time of most soft pneumatic actuators. Fourthly, to achieve onboard proportional control of multi-chamber soft robots, we developed an MRE valve array with an embedded cooling chamber. Physical experiments showed that our MRE valve array ensured the independence and accuracy of each valve unit within it, with a significantly lowered temperature of 73.9 $^o$C under 5 minutes of operation. Lastly, we developed an open-source software toolbox supporting the design of integrable pneumatic logic circuits to enhance their accessibility and performance. The toolbox comes with a graphical user interface (GUI) to take users' desired logic functions in the form of a truth table and a set of 2D space constraints related to the available space onboard the robot. It then schedules the pneumatic circuit which performs the desired computation within the space constraints and produces a 3D-printable CAD file that can be fabricated and used directly. The work presented in this thesis enables the community to simplify the process of integrating control devices into soft pneumatic robots, thereby paving the way for a new generation of fully untethered and autonomous soft robots

Autonomous Soft Robotic Fish Capable of Escape Maneuvers Using Fluidic Elastomer Actuators

In this work we describe an autonomous soft-bodied robot that is both self-contained and capable of rapid, continuum-body motion. We detail the design, modeling, fabrication, and control of the soft fish, focusing on enabling the robot to perform rapid escape responses. The robot employs a compliant body with embedded actuators emulating the slender anatomical form of a fish. In addition, the robot has a novel fluidic actuation system that drives body motion and has all the subsystems of a traditional robot onboard: power, actuation, processing, and control. At the core of the fish's soft body is an array of fluidic elastomer actuators. We design the fish to emulate escape responses in addition to forward swimming because such maneuvers require rapid body accelerations and continuum-body motion. These maneuvers showcase the performance capabilities of this self-contained robot. The kinematics and controllability of the robot during simulated escape response maneuvers are analyzed and compared with studies on biological fish. We show that during escape responses, the soft-bodied robot has similar input–output relationships to those observed in biological fish. The major implication of this work is that we show soft robots can be both self-contained and capable of rapid body motion.National Science Foundation (U.S.) (NSF IIS1226883)National Science Foundation (U.S.) (NSF CCF1138967)National Science Foundation (U.S.) (1122374