327 research outputs found
3D printed pneumatic soft actuators and sensors: their modeling, performance quantification, control and applications in soft robotic systems
Continued technological progress in robotic systems has led to more applications where robots and humans operate in close proximity and even physical contact in some cases. Soft robots, which are primarily made of highly compliant and deformable materials, provide inherently safe features, unlike conventional robots that are made of stiff and rigid components. These robots are ideal for interacting safely with humans and operating in highly dynamic environments. Soft robotics is a rapidly developing field exploiting biomimetic design principles, novel sensor and actuation concepts, and advanced manufacturing techniques.
This work presents novel soft pneumatic actuators and sensors that are directly 3D printed in one manufacturing step without requiring postprocessing and support materials using low-cost and open-source fused deposition modeling (FDM) 3D printers that employ an off-the-shelf commercially available soft thermoplastic poly(urethane) (TPU). The performance of the soft actuators and sensors developed is optimized and predicted using finite element modeling (FEM) analytical models in some cases. A hyperelastic material model is developed for the TPU based on its experimental stress-strain data for use in FEM analysis. The novel soft vacuum bending (SOVA) and linear (LSOVA) actuators reported can be used in diverse robotic applications including locomotion robots, adaptive grippers, parallel manipulators, artificial muscles, modular robots, prosthetic hands, and prosthetic fingers. Also, the novel soft pneumatic sensing chambers (SPSC) developed can be used in diverse interactive human-machine interfaces including wearable gloves for virtual reality applications and controllers for soft adaptive grippers, soft push buttons for science, technology, engineering, and mathematics (STEM) education platforms, haptic feedback devices for rehabilitation, game controllers and throttle controllers for gaming and bending sensors for soft prosthetic hands. These SPSCs are directly 3D printed and embedded in a monolithic soft robotic finger as position and touch sensors for real-time position and force control. One of the aims of soft robotics is to design and fabricate robotic systems with a monolithic topology embedded with its actuators and sensors such that they can safely interact with their immediate physical environment. The results and conclusions of this thesis have significantly contributed to the realization of this aim
Soft Gloves: A Review on Recent Developments in Actuation, Sensing, Control and Applications
Interest in soft gloves, both robotic and haptic, has enormously grown over the past decade, due to their inherent compliance, which makes them particularly suitable for direct interaction with the human hand. Robotic soft gloves have been developed for hand rehabilitation, for ADLs assistance, or sometimes for both. Haptic soft gloves may be applied in virtual reality (VR) applications or to give sensory feedback in combination with prostheses or to control robots. This paper presents an updated review of the state of the art of soft gloves, with a particular focus on actuation, sensing, and control, combined with a detailed analysis of the devices according to their application field. The review is organized on two levels: a prospective review allows the highlighting of the main trends in soft gloves development and applications, and an analytical review performs an in-depth analysis of the technical solutions developed and implemented in the revised scientific research. Additional minor evaluations integrate the analysis, such as a synthetic investigation of the main results in the clinical studies and trials referred in literature which involve soft gloves
Design, Modeling and Control of a 3D Printed Monolithic Soft Robotic Finger with Embedded Pneumatic Sensing Chambers
IEEE This paper presents a directly 3D printed soft monolithic robotic finger with embedded soft pneumatic sensing chambers (PSC) as position and touch sensors. The monolithic finger was fabricated using a low-cost and open-source fused deposition modeling (FDM) 3D printer that employs an off-the-shelf soft and flexible commercially available thermoplastic polyurethane (TPU). A single soft hinge with an embedded PSC was optimized using finite element modeling (FEM) and a hyperelastic material model to obtain a linear relationship between the internal change in the volume of its PSC and the corresponding input mechanical modality, to minimize its bending stiffness and to maximize its internal volume. The soft hinges with embedded PSCs have several advantages, such as fast response to very small changes in their internal volume (~0.0026ml/°), linearity, negligible hysteresis, repeatability, reliability, long lifetime and low power consumption. Also, the flexion of the soft robotic finger was predicted using a geometric model for use in real-time control. The real-time position and pressure/force control of the soft robotic finger were achieved using feedback signals from the soft hinges and the touch PSC embedded in the tip of the finger. This study contributes to the development of seamlessly embedding optimized sensing elements in the monolithic topology of a soft robotic system and controlling the robotic system using the feedback data provided by the sensing elements to validate their performance
3D printed flexure hinges for soft monolithic prosthetic fingers
Mechanical compliance is one of the primary properties of structures in nature playing a key role in their efficiency. This study investigates a number of commonly used flexure hinges to determine a flexure hinge morphology, which generates large displacements under a lowest possible force input. The aim of this is to design a soft and monolithic robotic finger. Fused deposition modeling, a low-cost 3D printing technique, was used to fabricate the flexure hinges and the soft monolithic robotic fingers. Experimental and finite element analyses suggest that a nonsymmetric elliptical flexure hinge is the most suitable type for use in the soft monolithic robotic finger. Having estimated the effective elastic modulus, flexion of the soft monolithic robotic fingers was simulated and this showed a good correlation with the actual experimental results. The soft monolithic robotic fingers can be employed to handle objects with unknown shapes and are also potential low-cost candidates for establishing soft and one-piece prosthetic hands with light weight. A three-finger gripper has been constructed using the identified flexure hinge to handle objects with irregular shapes such as agricultural products
A continuum robotic platform for endoscopic non-contact laser surgery: design, control, and preclinical evaluation
The application of laser technologies in surgical interventions has been accepted in the clinical
domain due to their atraumatic properties. In addition to manual application of fibre-guided
lasers with tissue contact, non-contact transoral laser microsurgery (TLM) of laryngeal tumours
has been prevailed in ENT surgery. However, TLM requires many years of surgical training
for tumour resection in order to preserve the function of adjacent organs and thus preserve the
patient’s quality of life. The positioning of the microscopic laser applicator outside the patient
can also impede a direct line-of-sight to the target area due to anatomical variability and limit
the working space. Further clinical challenges include positioning the laser focus on the tissue
surface, imaging, planning and performing laser ablation, and motion of the target area during
surgery. This dissertation aims to address the limitations of TLM through robotic approaches and
intraoperative assistance. Although a trend towards minimally invasive surgery is apparent, no
highly integrated platform for endoscopic delivery of focused laser radiation is available to date.
Likewise, there are no known devices that incorporate scene information from endoscopic imaging
into ablation planning and execution. For focusing of the laser beam close to the target tissue, this
work first presents miniaturised focusing optics that can be integrated into endoscopic systems.
Experimental trials characterise the optical properties and the ablation performance. A robotic
platform is realised for manipulation of the focusing optics. This is based on a variable-length
continuum manipulator. The latter enables movements of the endoscopic end effector in five
degrees of freedom with a mechatronic actuation unit. The kinematic modelling and control of the
robot are integrated into a modular framework that is evaluated experimentally. The manipulation
of focused laser radiation also requires precise adjustment of the focal position on the tissue. For
this purpose, visual, haptic and visual-haptic assistance functions are presented. These support
the operator during teleoperation to set an optimal working distance. Advantages of visual-haptic
assistance are demonstrated in a user study. The system performance and usability of the overall
robotic system are assessed in an additional user study. Analogous to a clinical scenario, the
subjects follow predefined target patterns with a laser spot. The mean positioning accuracy of the
spot is 0.5 mm. Finally, methods of image-guided robot control are introduced to automate laser
ablation. Experiments confirm a positive effect of proposed automation concepts on non-contact
laser surgery.Die Anwendung von Lasertechnologien in chirurgischen Interventionen hat sich aufgrund der atraumatischen Eigenschaften in der Klinik etabliert. Neben manueller Applikation von fasergefĂĽhrten
Lasern mit Gewebekontakt hat sich die kontaktfreie transorale Lasermikrochirurgie (TLM) von
Tumoren des Larynx in der HNO-Chirurgie durchgesetzt. Die TLM erfordert zur Tumorresektion
jedoch ein langjähriges chirurgisches Training, um die Funktion der angrenzenden Organe zu
sichern und damit die Lebensqualität der Patienten zu erhalten. Die Positionierung des mikroskopis chen Laserapplikators außerhalb des Patienten kann zudem die direkte Sicht auf das Zielgebiet
durch anatomische Variabilität erschweren und den Arbeitsraum einschränken. Weitere klinische
Herausforderungen betreffen die Positionierung des Laserfokus auf der Gewebeoberfläche, die
Bildgebung, die Planung und AusfĂĽhrung der Laserablation sowie intraoperative Bewegungen
des Zielgebietes. Die vorliegende Dissertation zielt darauf ab, die Limitierungen der TLM durch
robotische Ansätze und intraoperative Assistenz zu adressieren. Obwohl ein Trend zur minimal
invasiven Chirurgie besteht, sind bislang keine hochintegrierten Plattformen fĂĽr die endoskopische
Applikation fokussierter Laserstrahlung verfĂĽgbar. Ebenfalls sind keine Systeme bekannt, die
Szeneninformationen aus der endoskopischen Bildgebung in die Ablationsplanung und -ausfĂĽhrung
einbeziehen. Für eine situsnahe Fokussierung des Laserstrahls wird in dieser Arbeit zunächst
eine miniaturisierte Fokussieroptik zur Integration in endoskopische Systeme vorgestellt. Experimentelle Versuche charakterisieren die optischen Eigenschaften und das Ablationsverhalten. Zur
Manipulation der Fokussieroptik wird eine robotische Plattform realisiert. Diese basiert auf einem
längenveränderlichen Kontinuumsmanipulator. Letzterer ermöglicht in Kombination mit einer
mechatronischen Aktuierungseinheit Bewegungen des Endoskopkopfes in fĂĽnf Freiheitsgraden.
Die kinematische Modellierung und Regelung des Systems werden in ein modulares Framework
eingebunden und evaluiert. Die Manipulation fokussierter Laserstrahlung erfordert zudem eine
präzise Anpassung der Fokuslage auf das Gewebe. Dafür werden visuelle, haptische und visuell haptische Assistenzfunktionen eingeführt. Diese unterstützen den Anwender bei Teleoperation
zur Einstellung eines optimalen Arbeitsabstandes. In einer Anwenderstudie werden Vorteile der
visuell-haptischen Assistenz nachgewiesen. Die Systemperformanz und Gebrauchstauglichkeit
des robotischen Gesamtsystems werden in einer weiteren Anwenderstudie untersucht. Analog zu
einem klinischen Einsatz verfolgen die Probanden mit einem Laserspot vorgegebene Sollpfade. Die
mittlere Positioniergenauigkeit des Spots beträgt dabei 0,5 mm. Zur Automatisierung der Ablation
werden abschließend Methoden der bildgestützten Regelung vorgestellt. Experimente bestätigen
einen positiven Effekt der Automationskonzepte fĂĽr die kontaktfreie Laserchirurgie
Electroadhesive Auxetics as Programmable Layer Jamming Skins for Formable Crust Shape Displays
Shape displays are a class of haptic devices that enable whole-hand haptic
exploration of 3D surfaces. However, their scalability is limited by the
mechanical complexity and high cost of traditional actuator arrays. In this
paper, we propose using electroadhesive auxetic skins as a strain-limiting
layer to create programmable shape change in a continuous ("formable crust")
shape display. Auxetic skins are manufactured as flexible printed circuit
boards with dielectric-laminated electrodes on each auxetic unit cell (AUC),
using monolithic fabrication to lower cost and assembly time. By layering
multiple sheets and applying a voltage between electrodes on subsequent layers,
electroadhesion locks individual AUCs, achieving a maximum in-plane stiffness
variation of 7.6x with a power consumption of 50 uW/AUC. We first characterize
an individual AUC and compare results to a kinematic model. We then validate
the ability of a 5x5 AUC array to actively modify its own axial and transverse
stiffness. Finally, we demonstrate this array in a continuous shape display as
a strain-limiting skin to programmatically modulate the shape output of an
inflatable LDPE pouch. Integrating electroadhesion with auxetics enables new
capabilities for scalable, low-profile, and low-power control of flexible
robotic systems.Comment: Accepted to IEEE International Conference on Robotics and Automation
(ICRA 2023
Surgical Applications of Compliant Mechanisms:A Review
Current surgical devices are mostly rigid and are made of stiff materials, even though their predominant use is on soft and wet tissues. With the emergence of compliant mechanisms (CMs), surgical tools can be designed to be flexible and made using soft materials. CMs offer many advantages such as monolithic fabrication, high precision, no wear, no friction, and no need for lubrication. It is therefore beneficial to consolidate the developments in this field and point to challenges ahead. With this objective, in this article, we review the application of CMs to surgical interventions. The scope of the review covers five aspects that are important in the development of surgical devices: (i) conceptual design and synthesis, (ii) analysis, (iii) materials, (iv) maim facturing, and (v) actuation. Furthermore, the surgical applications of CMs are assessed by classification into five major groups, namely, (i) grasping and cutting, (ii) reachability and steerability, (iii) transmission, (iv) sensing, and (v) implants and deployable devices. The scope and prospects of surgical devices using CMs are also discussed
Force Sensing Surgical Grasper with Folding Capacitive Sensor
Minimally-invasive surgery (MIS) has brought many benefits to the operating room, however, MIS procedures result in an absence of force feedback, and surgeons cannot as accurately feel the tissue they are working on, or the forces that they are applying. One of the barriers to introducing MIS instruments with force feedback systems is the high cost of manufacturing and assembly. Instruments must also be sterilized before every use, a process that can destroy embedded sensing systems. An instrument that can be disposed of after a single use and produced in bulk at a low cost is desirable. Printed circuit micro-electro-mechanical systems (PCMEMS) is an emerging manufacturing technology that may represent an economically viable method of bulk manufacturing small, single-use medical devices, including surgical graspers. This thesis presents the design and realization of a PCMEMS surgical grasper that can fit within a 5 mm trocar, and can accurately measure forces in 3 axes, over a range of +/-4 N. The designed instrument is the first PCMEMS grasper to feature multi-axis sensing, and has a sensing range twice as large as current PCMEMS devices. Experimental results suggest that the performance of the sensing system is similar to conventionally-manufactured MIS instruments that use capacitive force transducers. The techniques applied in this thesis may be useful for developing a range of PCMEMS devices with capacitive sensors. Improvements to the design of the grasper and sensing system are suggested, and several points are presented to inform the direction of future work related to PCMEMS MIS instruments
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