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A robotic system for actively stiffening flexible manipulators
A system for actively changing the stiffness of a long, thin, flexible robotic manipulator has been designed for cardiologists to use in a range of diagnosis and treatment procedures. Low-stiffness manipulators, such as catheters, are ideal for steering through vasculature with low risk of tissue injury. However, such instruments are not well-suited for applying force to tissue. The proposed system solves this problem by using a series of bead-shaped vertebrae containing pull wires to actively change the stiffness of the catheter, similar to gooseneck surgical retractors. Individual wires steer the catheter to a desired location. All wires are then tensioned to create friction between each vertebra and prevent sliding, therefore resisting motion. While this design concept has been implemented manually in various settings for decades, fine robotic control of the friction and stiffness of the system relies on a thorough understanding of the friction properties between vertebral segments. We have developed an analytical model to understand the interactions between vertebrae and determine the relationships between system parameters and the overall stiffness of the catheter. Experiments validated the calculations from the model and the functionality of the system by applying known loads to the tip of the catheter and measuring the catheter displacement. The catheter stiffness was measured to range from 100 N/m to 800 N/m, which is sufficient for performing many surgical tasks on tissue. This system can be useful in minimally invasive procedures involving direct instrument contact with tissue by improving accuracy, safety, and work flow.Engineering and Applied Science
Soft Robot-Assisted Minimally Invasive Surgery and Interventions: Advances and Outlook
Since the emergence of soft robotics around two decades ago, research interest in the field has escalated at a pace. It is fuelled by the industry's appreciation of the wide range of soft materials available that can be used to create highly dexterous robots with adaptability characteristics far beyond that which can be achieved with rigid component devices. The ability, inherent in soft robots, to compliantly adapt to the environment, has significantly sparked interest from the surgical robotics community. This article provides an in-depth overview of recent progress and outlines the remaining challenges in the development of soft robotics for minimally invasive surgery
Development of a Tendon-Actuated Lightweight In-Space MANipulator (TALISMAN)
An invention of a new and novel space robotic manipulator is described. By using a combination of lightweight truss links, a novel hinge joint, tendon-articulation and passive tension stiffening, this new robotic manipulator architecture achieves compact packaging, high strength, stiffness and dexterity while being very lightweight compared to conventional manipulators. The manipulator is also very modular; easy to scale for different reach, load and stiffness requirements; enabling customization for a diverse set of applications. Novel features of the new manipulator concept are described as well as some of the approaches to implement these design features. Two diverse applications are presented to show the versatility of the concept. First generation prototype hardware was designed, manufactured and has been assembled into a working manipulator that is being used to refine and extend development efforts
Continuum Robots for Space Applications Based on Layer-Jamming Scales with Stiffness Capability
Continuum robots, which have continuous mechanical structures comparable to the flexibility in elephant trunks and octopus arms, have been primarily geared toward the medical and defense communities. In space, however, NASA projects these robots to have a place in irregular inspection routines. The inherent compliance and bending of these continuum arms are especially suitable for inspection in obstructed spaces to ensure proper equipment functionality. In this paper, we propose a new solution that improves on the functionality of previous continuum robots, via a novel mechanical scaly layer-jamming design. Layer-jamming assisted continuum arms have previously required pneumatic sources for actuation, which limit their portability and usage in aerospace applications. This paper combines the compliance of continuum arms and stiffness modulation of the layer jamming mechanism to design new hybrid layer jamming continuum arms. The novel designs use an electromechanical actuation which eliminates the previous need for pneumatic actuation therefore making the hardware compact and portable
Bioinspired Soft Actuation System Using Shape Memory Alloys
Soft robotics requires technologies that are capable of generating forces even though the bodies are composed of very light, flexible and soft elements. A soft actuation mechanism was developed in this work, taking inspiration from the arm of the Octopus vulgaris, specifically from the muscular hydrostat which represents its constitutive muscular structure. On the basis of the authors’ previous works on shape memory alloy (SMA) springs used as soft actuators, a specific arrangement of such SMA springs is presented, which is combined with a flexible braided sleeve featuring a conical shape and a motor-driven cable. This robot arm is able to perform tasks in water such as grasping, multi-bending gestures, shortening and elongation along its longitudinal axis. The whole structure of the arm is described in detail and experimental results on workspace, bending and grasping capabilities and generated forces are presented. Moreover, this paper demonstrates that it is possible to realize a self-contained octopus-like robotic arm with no rigid parts, highly adaptable and suitable to be mounted on underwater vehicles. Its softness allows interaction with all types of objects with very low risks of damage and limited safety issues, while at the same time producing relatively high forces when necessary
Embodiment design of soft continuum robots
This article presents the results of a multidisciplinary project where mechatronic engineers worked alongside biologists to develop a soft robotic arm that captures key features of octopus anatomy and neurophysiology. The concept of embodiment (the dynamic coupling between sensory-motor control, anatomy, materials and environment that allows for the animal to achieve adaptive behaviours) is used as a starting point for the design process but tempered by current engineering technologies and approaches. In this article, the embodied design requirements are first discussed from a robotic viewpoint by taking into account real-life engineering limitations; then, the motor control schemes inspired by octopus nervous system are investigated. Finally, the mechanical and control design of a prototype is presented that appropriately blends bio-inspiration and engineering limitations. Simulated and experimental results show that the developed continuum robotic arm is able to reproduce octopus-like motions for bending, reaching and grasping
Snake-Like Robots for Minimally Invasive, Single Port, and Intraluminal Surgeries
The surgical paradigm of Minimally Invasive Surgery (MIS) has been a key
driver to the adoption of robotic surgical assistance. Progress in the last
three decades has led to a gradual transition from manual laparoscopic surgery
with rigid instruments to robot-assisted surgery. In the last decade, the
increasing demand for new surgical paradigms to enable access into the anatomy
without skin incision (intraluminal surgery) or with a single skin incision
(Single Port Access surgery - SPA) has led researchers to investigate
snake-like flexible surgical devices. In this chapter, we first present an
overview of the background, motivation, and taxonomy of MIS and its newer
derivatives. Challenges of MIS and its newer derivatives (SPA and intraluminal
surgery) are outlined along with the architectures of new snake-like robots
meeting these challenges. We also examine the commercial and research surgical
platforms developed over the years, to address the specific functional
requirements and constraints imposed by operations in confined spaces. The
chapter concludes with an evaluation of open problems in surgical robotics for
intraluminal and SPA, and a look at future trends in surgical robot design that
could potentially address these unmet needs.Comment: 41 pages, 18 figures. Preprint of article published in the
Encyclopedia of Medical Robotics 2018, World Scientific Publishing Company
www.worldscientific.com/doi/abs/10.1142/9789813232266_000
Stiffness Change for Reconfiguration of Inflated Beam Robots
Active control of the shape of soft robots is challenging. Despite having an
infinite number of passive degrees of freedom (DOFs), soft robots typically
only have a few actively controllable DOFs, limited by the number of degrees of
actuation (DOAs). The complexity of actuators restricts the number of DOAs that
can be incorporated into soft robots. Active shape control is further
complicated by the buckling of soft robots under compressive forces; this is
particularly challenging for compliant continuum robots due to their long
aspect ratios. In this work, we show how variable stiffness can enable shape
control of soft robots by addressing these challenges. Dynamically changing the
stiffness of sections along a compliant continuum robot can selectively
"activate" discrete joints. By changing which joints are activated, the output
of a single actuator can be reconfigured to actively control many different
joints, thus decoupling the number of controllable DOFs from the number of
DOAs. We demonstrate embedded positive pressure layer jamming as a simple
method for stiffness change in inflated beam robots, its compatibility with
growing robots, and its use as an "activating" technology. We experimentally
characterize the stiffness change in a growing inflated beam robot and present
finite element models which serve as guides for robot design and fabrication.
We fabricate a multi-segment everting inflated beam robot and demonstrate how
stiffness change is compatible with growth through tip eversion, enables an
increase in workspace, and achieves new actuation patterns not possible without
stiffening
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