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The generation of plastic parts in small volume batches has an enormous economic significance. Application fields for parts in small lot sizes are the fabrication of prototypes in the design process or individualized products. The goal thereby often is not only to produce show objects, but functional parts with specific materials, high dimensional accuracy and proper mechanical properties in a short amount of time. The conventional way to produce thermoplastic plastic parts is given by injection molding and extrusion. Characteristics for this technology are the resulting good and homogeneous mechanical component properties, but shape freedom is limited and the process is time consumptive because an individual tool is needed for each product. Depending on the design of the part the geometry of the tool can be complex and an iterative process is necessary to create a suitable mold. On the other hand, the technology of additive manufacturing is a growing market for the quick and cheap production of parts as prototypes, but still the range of materials is limited and anisotropic mechanical component properties are ongoing problems. The combination of both technologies is known as rapid tooling, where the mold is produced in an additive manufacturing process and then used in an injection molding or casting process. This approach combines the benefits of both technologies in term of time and cost efficiency and good component properties. Problems here are the combination of different materials for mold and component and the missing process knowledge and automatization. In this paper an extrusion-based additive manufacturing technology is used to combine additive manufacturing and injection infill generation for thermoplast in one process. The proposed working principle is to generate the outer contour of the part by filament extrusion as mold to ensure high accuracy and good surface quality and fill the mold using an extrusion process of polymer melt without filament generation. Accordingly, the mold becomes part of the component and the same material can be used for the mold and the infill. Since the viscosity of most thermoplastic polymer melts is too high to fill big structures and undercuts, an algorithm is proposed to generate a chamber structure inside the part. Consequently, the fabrication process consists of several iterative cycles of mold generation and injection processes. For this paper polyamide 6 is used to demonstrate the process. Experiments were performed to find the optimal chamber geometry and size to avoid holes and generate a high quality infill. Several component properties such as density, tensile strength and fabrication time are analyzed. In spite of still existing blowholes, a higher component density could be achieved with the proposed process compared to additive manufacturing. However, the tensile strength is still significantly lower. The failures appeared at the weld lines, where warm polymer melt was injected to already colder chambers below. Still manual processes are sources of possible defects as well. The integration of a RFID chip is shown as an additional feature of the process of easy integration of passive electronic elements.

Since the minimally invasive surgery has significant benefits for the patient, special equipment and techniques are constantly enhanced in this relatively new surgical field, so that more challenging surgical applications can be achieved. Thereby, the major aim is to enable the surgeon to manipulate instruments inside the human body intuitively, despite restricted access to the operating field and limited workspace. With our spine like overtube system for use with standard endoscopes and standard endoscopic instruments, we provide a system facilitating tissue manipulation with sufficient triangulation. In this paper we describe our 3D-printed manipulator system for minimally invasive applications and its pure mechanical control and actuation concepts. Following our aim of an individualized disposable system, in a first step we demonstrate the feasibility of a 3D-printed surgical robotic system by laboratory experiments and a clinical evaluation on a porcine model.

Today’s landscape of medical devices is dominated by stand-alone systems and proprietary interfaces lacking cross-vendor interoperability. This complicates or even impedes the innovation of novel, intelligent assistance systems relying on the collaboration of medical devices. Emerging approaches use the service-oriented architecture (SOA) paradigm based on Internet protocol (IP) to enable communication between medical devices. While this works well for scenarios with no or only soft timing constraints, the underlying best-effort communication scheme is insufficient for time critical data. Real-time (RT) networks are able to reliably guarantee fixed latency boundaries, for example, by using time division multiple access (TDMA) communication patterns. However, deterministic RT networks come with their own limitations such as tedious, inflexible configuration and a more restricted bandwidth allocation. In this contribution we overcome the drawbacks of both approaches by describing and implementing mechanisms that allow the two networks to interact. We introduce the first implementation of a medical device network that offers hard RT guarantees for control and sensor data and integrates into SOA networks. Based on two application examples we show how the flexibility of SOA networks and the reliability of RT networks can be combined to achieve an open network infrastructure for medical devices in the operating room (OR).

Surgical navigation systems based on optical tracking technology all suffer from the requirement for an unobstructed line-of-sight. The optical path between stereo camera and tracked objects has to be kept free or the navigation is suspended. In this article, we present a new module that combines the information of two tracking cameras simultaneously, to view the surgical site from two different angles. The module is designed to work with legacy navigation systems and established tools in order to facilitate its way into the operating room. With the new module, the staff's workspace can be expanded and the availability of navigation information during an intervention can be increased.

Medical devices are becoming ever more complex through constant integration of new technologies. From a regulatory perspective guaranteeing safety and low risks associated with these devices is becoming increasingly challenging for device manufacturers. This work is based on a previously developed novel software tool for risk management of medical devices. The software implements relational links among technical documents and thereby integrates sections such as system components, system requirements, product manual and others into risk management in order to increase traceability and consistency. In this paper the developed software tool was experimentally evaluated and compared to the state of the art methodology by a usability study with 14 subjects. Results show a higher mean effectivity, efficiency and subjective user satisfaction for our tool. User satisfaction could be proven to be significantly higher for our tool with a significance level of 5%.

Minimally invasive surgery offers the benefits of reduced patient trauma, faster recovery and shorter hospital stay to the patients, what motivates its development towards further less invasive applications. In this work, we present a concept for adapting our 3D-printed overtube manipulator to single incision laparoscopic surgery. Furthermore, we describe the integration of a surgeon supporting ultrasound imaging into the manipulator system, which can be used to supply augmented reality features. With our concept, we aim to meet the demand for systems that enable enhanced tissue manipulation as well as the request for the supply of additional information for the surgeon regarding the inside of organs and tissue structures in order to improve the surgical outcome.

Capsule endoscopes used for diagnosis in the gastro intestinal tract have gained much popularity in recent years due to the minimized patient discomfort and available operating range. New therapeutic applications of these devices are surgical interventions or medication at specific locations. So far capsule endoscopic devices are passively propelled prohibiting these new approaches. To overcome this issue we presented a Magnet Drive Unit (MDU) for external actuation for robotic capsule devices in our previous work. While MDU is used for manipulation of a capsule-robot, there has not been any information of the current location of the robot within the patient. Therefore, we propose a novel ultrasound based tracking system for the capsule-robot and endoscopic devices in this manuscript. The tracking system consists of a Cartesian robot actuating a transcutaneous sonographic probe in two degrees of freedom. While the capsule-robot is propelled by MDU, our tracking system generates sonographic images through the back of the patient showing the current location of the capsule. The results of our experiments unveil that our concept is feasible and can be used to navigate a robotic capsule device inside the human body.

During the implantation of Deep Brain Stimulation Electrodes for the treatment of Parkinson's disease the operating team of neurosurgeons and neurologists evaluates the symptom improvement at multiple electrode positions in order to decide where a permanent electrode can achieve the best benefits. This evaluation is done and documented manually. In this project a mechatronic device has been developed that measures the main symptoms rigidity, tremor and bradykinesia. The acquired data support the neurologist to decide on the implantation site. This paper describes the software architecture of the device, since the software on the mechatronic device as well as the user-software presenting the data to the neurologist are essential for the benefit of the decision were to place the electrode.

The development of minimally invasive surgery will lead to the further reduction of incisions regarding single-port surgery using only one single artificial or natural incision. Thus, it appears that instruments and workflow have to be designed in a way that provides a dexterous manipulation of instruments inside the body. The aim should be to support the surgeon with a system most suitable to the specific application. This article presents the concept of designing an individualized robot for minimally invasive surgery (e.g. partial nephrectomy) on basis of our Multi-Arm Snake-Like Robot. The system is designed as overtube for standard optics in minimally invasive surgery and possesses articulated arms to manipulate standard instruments enabling the physician to manipulate tissue from two sides (triangulation of the instruments). By using additive manufacturing and new design algorithms, we were able to design robotic structures adaptable to different clinical applications such as endoscopic or laparoscopic interventions. This paper presents the first step towards a patient, surgeon and task specific automated design of disposable robots.

The tympanoplasty-III is a widely used method to heal the conductive hearing loss with passive prostheses. One of the major challenges during this procedure is to determine the correct prosthesis length during the surgery, in order to apply an optimal tension on the tissues. However, a suboptimal tension on the tissues may occur because of a varying ambient pressure and tissue changes after the operation. This may decrease the quality of sound conduction, cause prosthesis luxation and even injure the tympanic membrane or inner ear. Yet, the state of the art prostheses can only be adjusted during the operation and they cannot adapt themselves to these postoperative changes. In this paper, we present a manufacturing concept for a new middle ear prosthesis that can adapt its length to postoperative changes. Our work on the manufacturing process includes an early concept evaluation with a finite element model as well as our first outcomes with the manufactured prosthesis models.

Surgical interventions at the middle ear are very challenging tasks for surgeons. At an otosclerosis the stapes is immobile because of an abnormal bone growth so that the sound transmission is disturbed. Therefore, a stapedotomy is performed where the stapes is partly replaced by a small implant to reconstruct the path of sound transmission. The state of the art is to use handheld micro instruments. However, the structures are, as well as the required precision, in the range of sub-millimeters, and the view is limited due to the narrow ear canal. Because of the human hand tremor, which goes from some tenth millimeters up to some millimeters, the intervention is very delicate. Until now, there are no assistance systems for guiding surgical instruments available. In this contribution we present the further development of a formerly presented micro-macro telemanipulator system. New functionality for coarse and fine positioning was implemented, as well as a processing unit and a quick-changer for exchanging the micro manipulator. In a preliminary experiment standard-based position repeatability is obtained. It is shown that the repeatability of the current macro robot is appropriate for the task and so the approach has high potential for supporting the surgeon in ENT surgery.

In this article, we present a new physical model for the surgical simulation of interventions in the middle ear and temporal bone. The goal of the work was to provide on one side a detailed and easy to use model for the training of stapes plastic surgeries and on the other side a realistic testing environment for a surgical robotic system formally presented of our group. The stapedotomy, a common stapes plastic, is an intervention at the middle ear to reconstruct the path of sound transmission using a small implant. It is performed, e.g., in case of a conductive hearing loss due to an otosclerosis, which is a disease of abnormal bone growth at the stapes, the smallest of the auditory ossicles. The training of the intervention is typically done at human preparations. However, there is a lack of reproducibility and availability. The presented new physical middle ear model allows to simulate the main steps of stapes plastics including the manipulation of bone structures and inserting a stapes-prosthesis. It contains of a detailed 3D printed temporal bone with a flexible and removable ossicular chain coming from high resolution μCT (micro computed tomography) data. Our experiments show, that it is possible to perform the main steps of the stapedotomy close to the real procedure. The anatomic structures are realistic enough for the purpose. As far as we know, it is the first physical model, with removable ossicles, as well as a modular auditory canal and middle ear area, for simulating the implantation of stapes-prosthesis fabricated by 3D printing.

This paper describes the concept and realization of a handheld device for the implant deployment during the minimally-invasive closure of the left atrial appendage (LAA). This implant serves as stroke prevention for patients suffering from atrial fibrillation. The implant is delivered by a catheter and unfolds automatically when it leaves the catheter. According to the user manual the deployment of the implant takes place in three steps with the user having to move two components in predetermined distances and directions to ensure the safe deployment. The mechanism described in this paper solves this task by converting a continuous rotational input at the user interface into an intermittent translational movement of the two components through the use of a star wheel drive. The paper describes the construction and calculation of the device and in detail the gear and presents an experiment that showed the potential advantages of the device.

This contribution presents different concepts for base stations complementing a fluid intake monitoring system. The motivation behind this research is the high amount of dehydration diagnoses in hospitals. Affected patients are almost exclusively elderly people. Therefore a monitoring system is needed that is able to detect insufficient fluid intake, especially designed for this demographic group. The foundation of this system is based on smart sensor cups which are able to deduce fluid intake by detecting the filling level. This paper focuses on complementary devices for these cups which are necessary in order to build an exhaustive monitoring system. Depending on the intended scenario, the primary functions are charging the sensor cups and receiving and displaying data. This data is either displayed for an immediate feedback or subsequently transferred to a central server for storage in a database or further processing. This contribution presents three different concepts: a simple multi charging station for up to four cups simultaneously, a stand-alone base station able to charge and display informations gathered by one sensor cup and a network-compatible base station for several cups. The system mentioned last is also able to transfer their data via Ethernet to a server. The interface between sensor cup and system as well as their intended use are presented in detail for each concept. The evaluation concentrates on the reliability of a system build on scenarios around the network-compatible base station.

This paper presents an investigation of ideal geometry and material parameters of piezo-driven axisymmetric unimorph actuators for micropump applications. Based on Classic Laminated Plate Theory, closed form expressions for the transverse and radial displacement under diverse loads are derived for two types of unimorph actuators. The general approach allows an application of this theory to almost arbitrary actuator geometries. Using analytical and numerical methods, both actuators are optimized to achieve maximum stroke volume at predefined pressure conditions. In this process, strikingly simple expressions are found, constituting the theoretical maximum stroke volume of a circular bender type actuator. The optimization is complemented by a non-linear FEM study that confines the scope of the the analytical results. In summary, the optimization procedure presented in this paper facilitates the design of piezoelectrically driven unimorph diaphragm actuators by providing generic design rules regarding materials and geometrical dimensions.

PurposeThis paper aims to verify a new method for accurate part manufacturing using a 3D printer. In particular, the direction and position dependence of the printed results are to be verified within the building area. The results of the accomplished experiments are to be used for the computation of new printer adjustments.Design/methodology/approachTest cubes with a defined edge length were printed and measured afterwards. The test cubes were distributed thereby either over the entire building area or only for a small part of the building area. Next, the test cubes were measured and the differences between measured and desired values were used for adjustment of the printer parameter settings. Therefore, the “bleed compensation” settings were used.FindingsThe deviations depended strongly on the position in the building area of the printer. In dependence of the position and orientation, different deviations in the three dimensions of the printer coordinate system resulted. By a calibration of the printer parameters for a reduced part of the processed area, the print accuracy could be strongly increased. Afterward, the calibration the deviations could be reduced from 0.4 mm ±0.2 mm to under 0.04 mm ±0.03 mm.Originality/valueThe work shows the position and direction dependency of the 3D‐printer manufacturing accuracy. Furthermore, a calibration procedure for bleed compensation calibration is presented.

This contribution presents an automated approach to generate drinking protocols. This documentation process is used in nursing homes in order to prevent dehydration in elderly people. Smart cups are used to deduce fluid intake from filling levels. Electrodes at different vertical positions allow to detect discrete filling levels depending on the amount of beverage in the cup. A conductive sensor is combined with an inductive charging unit and a radio module in order to build a functional prototype with regard to food compliance, dishwasher compatibility and subtle appearance. An evaluation of the sensor has shown a strong influence of the beverage type. While water and most soft drinks result in unambiguous measurements, remnants, especially of milk, disturb an interpretation of sensor values severely. However, the prototype offers a reliable way to automatically monitor fluid intake of those unproblematic beverages.

The concept presented in this paper describes two new approaches to integrate transfer support functions into wheelchairs. The goal is to relieve caregivers and nurses in their daily task of lifting patients from and to the wheelchair without the need of an additional external lift device, such as commonly used lifting cranes or lifting belts. The contributions of this paper are (i) the design of two different mechanical linkages, which realize two types of transfer motions, (ii) the selection of a passive actuator for weight compensation and simulation of the force induced by it (static design), as well as (iii) the experimental evaluation of the simulation using rapid prototyping functional models of the concepts. The results are two different design concepts, each of which can realize a particular, smooth transfer motion.

In this contribution we present a portable system which records interactions with objects of daily use automatically. The system is based on an Ultra High Frequency (UHF) Radio-Frequency IDentification (RFID) device and can be worn around the wrist. It is able to detect proximity to objects marked with an RFID tag, store collected information and transfer it wirelessly to a server. Such devices are developed worldwide to enable elderly people to live independently at home as long as possible. One approach, which we aim at with our concept, is to record Activities of Daily Living (ADL), thus making cognitive decline in elderlies easier to detect and compensate. Compared to other approaches (e.g. video/audio surveillance, presence sensors, floor pressure sensors), RFID-based solutions have the advantage of preserving the user's privacy, being robust with multiple inhabitants (or pets) and being easy and low-cost to install. However, their detection range and portability tend to be lower. In this article we present the concept and its evaluation in respect to the achievable detection range and ability to detect proximity to objects in a simulated breakfast scenario.

This paper presents an evaluation of an algorithm that optimises the infills of the geometries that contain at least one pointed end. Computation of the infills, as a part of path planning, falls within the slicing procedure, which in turn is a standard process step in creating a 3D part via rapid prototyping techniques. The computation of the infill trajectories were conducted according to its final application — a droplet generating 3D printer that extrudes plastic droplets on a moving platform. The most commonly used infill techniques are several boundary contours followed by either raster lines or further contours. With these standard techniques particular geometries that contain narrow sub-geometries or pointed ends are not properly filled. The improper infilling results partly due to the limitation on the size of the extruding unit and partly due to the standard trajectories, that do not take in account particular geometry shapes. In particular, the faulty infilling results in voids (underfills) and/or bulges (over-fills). In their previous work, the authors presented a novel algorithm, that concentrates on the pointed end geometries and computes the trajectories for the droplet positioning such that the under-fills and over-fills are minimised. As an extension to the proposed algorithm, this paper presents the algorithm outcome in a form of a look-up table. To every sharp angle a number of insertions of additional droplets, as well as the number of deletions is assigned. Moreover, a 3D model of a pointed end has been sliced and filled according to the algorithmic results and compared with the 3D parts filled according to the standard infill techniques. The printed parts demonstrate the effectiveness of the improved infills. After measuring the height profile of the different parts, the parts printed as suggested by the algorithm led to the smoothest final surface.

Dehydration among elderly people is both a widespread and health threatening problem which requires continuous monitoring of beverage intake. In this contribution a concept for a system for automatic detection of filling levels based on radio frequency identification (RFID) is presented. It consists of passive sensor cups including a resistive sensor system and an RFID transponder as well as an RFID reader with an interface for analyzing gathered data on a PC. This concept is evaluated using a prototype in respect to range and accuracy of single and connected measurements. It is demonstrated that RFID based monitoring of drinking behavior is possible and achieves results comparable to the state of the art independently of beverages.

The goal in minimally-invasive surgery like NOTES (natural orifice transluminal endoscopic surgery), or single-port surgery, through one artificial incision, is to reduce the operative and post-operative stresses for the patients. Today's challenges for physicians during procedures are the missing mobility of the used flexible instruments inside the human body. Primarily the missing ability to manipulate tissue from different sides (triangulation of instruments) needs to be obtained. This article proposes the next prototype of our Multi Arm Snake-Like Robot and focuses on the kinematic development of the overtube body-frame for the flexible endoscope. We are following a new way developing a system for minimally- invasive surgery by using additive manufacturing methods like selective laser sintering (SLS). By using SLS it is feasible to create stiff structures with local flexure hinges monolithically that are custom made adapted for different patients and surgeries. To adapt our systems to different standard endoscopic equipment, procedures and patients we use a unique puzzle-clip mechanism. In the experiment the modularization of the system through the puzzle-clip system is shown. The used raw material PA 2200, a polyamide based thermoplastic polymer, is certificated as biocompatible according to DIN EN ISO 10993. This proves that the proposed Multi Arm Snake-Like SLS Robot system gets more advances towards the use during minimally-invasive procedures. And has a high chance to reach the final goal the clinical certification.

In the present paper a compact model for a piezoelectric drop-on-demand (DoD) printhead is derived from basic electrical, mechanical and fluid mechanical relationships. The model covers the whole droplet generation process, spanning over the electrical as well as the mechanical and fluidmechanical domains. It allows predictions about essential droplet characteristics, such as droplet volume and flight velocity, for a given set of droplet generator (DG) dimensions, material and fluid properties and a predetermined electrical excitation. This enables the targeted adaption of the droplet generator's design to varying application requirements, such as different fluid properties, with a minimum number of design iterations. The model is implemented by transferring the resulting differential equations to the Matlab/SIMULINK™ simulation environment. It is verified by comparing its output with an extensive empirical dataset which is obtained by fabricating a selection of droplet generators with different geometrical dimensions and testing them with several different fluids. Despite the fact that the model is based on strongly simplified physical relationships, it is able to accurately predict the minimum excitation voltage needed for droplet generation as well as the droplet velocity. However, the volume of the ejected droplets could not be predicted with satisfactory results, which is attributed to the limited accuracy of the nozzle submodel.

The middle ear is a sophisticated mechanism which transmits sound waves from the outer ear to the inner ear, while it amplifies and filters the sound waves depending on their frequency. However, the sound path can be broken due to traumas, infections, ossification or alteration. In this case, the surgeons reconstruct the sound path with an implant, mostly with passive titanium prostheses. Developers need an environment to validate these implants. The current environment for this purpose is the human temporal bone from cadavers, which does not provide reproducible conditions for experiments. In this paper, we present a new anatomical human middle ear model. We have segmented the essential functional elements from μCT-data (micro computed tomography). We have reproduced the bony structures with a 3D printer and the soft tissues with silicone rubber casting. Our experiments show that the model transmits the sound waves from the tympanic membrane to the inner ear as in a human middle ear. We also present that the articulated ossicles are suitable to reconstruct the ossicular chain with different types of passive prostheses.

Electromagnetic position sensing in navigation of metallic instruments requires measures for compensating for error due to distortions of the generated electromagnetic field by the metallic objects. In dental implantology, the working volume can be modelled by a plate at a defined position. Pitch, yaw and movements along the drill axis of the tool in the active working volume are small. Thus, error compensation is necessary only for three degrees of freedom for this application. We build a setup for the instrument navigation with a field generator fixed to a patient seat and performed tool calibrations in a defined working volume. During calibration, a vector field of error vectors was found and stored in a look-up table. The pose-dependant error vectors are determined at fixed supporting points and defined rotations around the drill axis of the tool. Entries of the look-up table were used to compensate for errors during navigation. Two experiments were performed, both resulting in positioning accuracy below 1 mm. Yet, robustness for clinical use of the method has to be proven.

A new experimental support system for milling cavities for cochlear implants is proposed. In contrast to assisting the milling task by drilling jigs, image-based navigation systems or robots, the approach of “Navigated Control” features a supervision of the power of the user controlled instrument. The main feature is the decrease of the power of an active instrument depending on the location of this instrument relative to a planned volume. A first experiment to determine the accuracy of the system in contrast to conventional manual milling is presented. The accuracy of the manual milling with “Navigated Control” was at 0.2 ± 0.2 mm compared to the lower accuracy of the conventional manual milling without “Navigated Control” at 0.8 ± 0.2 mm. The results are discussed.

Medical Robotics Workshop MRWS Kevin Cleary a; Brian Davies b; Gabor Fichtinger c; Jocelyne Troccaz d; Tim Lueth e; Vance Watson f a ISIS Center, Department of Radiology, Georgetown University Medical Center, Washington, DC, USA b Department of Mechanical Engineering, Imperial College, London, UK c Center for Computer-Integrated Surgery, Johns Hopkins University, Baltimore, Maryland, USA d Laboratoire TIMC, Faculte de Medecine, Universite Joseph Fourier, Grenoble, France e Surgical Navigation and Robotics Lab, Charite Campus Virchow, Berlin, Germany f Department of Radiology, Georgetown University Hospital/MedStar Health, Washington, DC, USA

In this paper the problem of under-filled pointed ends is introduced and mathematically defined. To tackle this problem, we present a new algorithm that detects and fills the critical areas, which arise at the 3D printed plastic parts. While printing the contours and/or infill lines, due to the limitations based on the width of the extruded material, narrow edges and pointed ends remain improperly filled. This eventually results in 3D printed objects with the final geometry that differs greatly from the initial geometry. This paper presents the fundamentals for solving the problem of 3D printing of geometries which contain narrow pointed ends. The critical area of the pointed ends is mathematically defined and, depending on the angle, the formulae for the calculation of under-filled and over-filled areas are given. The newly developed algorithm, based on the 3D Printing plastic droplet generation process, assures that the droplets of the repeating contours are placed at the edges of the contour-segments and by that minimises the potential under-fills. Furthermore, an additional number of droplets is defined, that are either printed in or removed from the under-filled areas in the angle bisector. The proposed algorithm is applied on parts, whose geometry describes pointed ends. The final 3D printed parts are very appealing and their shape resembles the original geometry more than the final shape of the parts without applying the algorithm.

The use of three-dimensional scanning techniques in the medical field has become increasingly relevant. Laser projection systems have been applied onto human skin tissue in a variety of ways, especially in navigated surgery. However, a highly accurate and portable scanning system with the ability to analyze human tissue from multiple recording directions has yet to be developed and certified as a Class I medical device. This project aims to find the ideal setup of a portable, intuitive and certified scanning system of human tissue without the need of projective equipment. The scanning tool consists of a stereo camera by Northern Digital Instruments (NDI) and an infrared laser module. This paper presents the system’s ideal parameter settings while varying its accuracy when applying a laser module with wavelength of 850nm onto human tissue.Copyright © 2014 by ASME

Accurate three dimensional scanning of surfaces, especially on humans, is more and more relevant. The usage of laser projection systems is widespread. However, a medical certification Class I, high accuracy, a flexible and not static handling as well as the ability to record from more than one direction has never been combined in a single device. Our project aims at the ideal setting for an easy to use, flexible scanning method from more than one recording direction for human tissue without a need of protective equipment. A minimum of requirements for the user and the system itself, as well a possible certification as medical product shall be implemented using a high accurate NDI stereo camera. Interactions and influences of the considered laser modules and reflectors on/with the camera were examined. In this paper, we present, to the authors' best knowledge, novel results of an ideal parameter setting and the requirements based on an 850nm laser module and human tissue for possible applications in navigated surgery or individualized prosthetics.

This chapter provides a kinematic design approach for specific folding structures, consisting of vertices with four intersecting creases, such that they can achieve two given folding configurations. These configurations are defined in terms of up to two planar curves, which are approximated by a polyline that is a particular part of the folding structure. We call these structures Miura-ori-based structures or linkages because the design approach makes use of the particular motion characteristics of the 1-DOF mechanism equivalent of the Miura-ori folding pattern. To achieve the design goal we apply a two-configuration synthesis, also provided in a previous work, which is based on the screw axis of a specific relative displacement. A classification of the slide along the screw axis allows it to determine the creases connecting consecutive links of the folding structure as revolute joints.

In this paper a new slicing method for filling an arbitrary polygon with 3D-balls for a 3D plastic droplet generation process is presented. The work principle of the 3D plastic droplet generation is to squeeze the plastic material through a nozzle, out of which small hardened balls are formed and based on the contour and infill algorithm the 3D objects filled with plastic droplets are layer-wise created. Zigzag lines and the Shrinking contours infill strategies, used in the most slicing software of the similar rapid prototyping process Fused Deposition Modelling (FDM) are applicable in this case as well, but do not take advantage of utilising droplets. In the proposed algorithm, each of the slices with contour polygons is intersected with a constant fixed 3D densest sphere formation. Those spheres, which are within a polygon of a certain slice, are forming printed droplets. The droplet placement is by applying this algorithm predefined and completely controlled. Moreover, the holes within a slice, as well as between the slices are minimised and regularly scattered. In the experiment the density of a cube filled with droplets with three different infill strategies (Zig-zag, Shrinking contours and the dense 3D packing) is measured and the dense 3D packing method results in the highest density. This method leads to achieving the goal of producing the 3D objects with fine surface quality and sufficient stability.

In this paper the sensing and control mechanism for an interactive controlled robot system is presented. The described robot is the first active surgical robot system for maxillofacial surgery in a clinical environment. The robot is teached and operated by an interactive control concept that allows the user to guide the robot directly by grasping and manipulating the TCP of the robot. Since the robot is manipulating a patient's skull bone and it is guided at the same time by a surgeon using die TCP sensing, control, safety, and man-machine-interface are of paramount importance.

The main advantage of distributed controlled robots and subsystems is the decentralized task execution by the system components. In this way, properties for the design of flexible control architectures like modularity, fault-tolerance, integrability and extendibility are easily obtained; furthermore, it is possible to use the concepts of distributed knowledge and decentralized world representation. On the other hand, coordination between the components, e.g. path planning for collision avoidance between both manipulators in a two-arm system, is very difficult to guarantee. To explain these concepts, the Karlsruhe Autonomous Mobile Robot (KAMRO), which is being developed at our institute, is considered. The robot system consists of several subcomponents like two manipulators, hand-eye cameras, one overhead camera and a mobile platform. Extensions to the distributed control architecture KAMARA (KArlsruhe Multi-Agent Robot Architecture) are described that are used to overcome coordination problems, e.g. as c...

Fabrication of plastic parts is an important scope of application for various branches of industry. This does not only concern manufacturing of end products but also production of sample parts in small lot sizes. Currently, most plastic parts are injection-molded. Consequently, it is first necessary to produce appropiate moldings, for example by milling of metal. This is very time-consuming on one hand and uneconomical concerning costs for production in small lot sizes on the other hand. Furthermore, the variety of forms is restricted considerably which is a clear disadvantage concerning the production of prototypes or spare parts. The use of a free-forming droplet generator for producing plastic parts can provide remedy. The patented principle of the printing process used in this approach is to produce droplets of liquified plastic in a preparation unit. Sequential discharge of these droplets builds a part in the installation space by solidifying of the droplets into balls. Since each 3D printing process needs its own data preprocessing, this article presents its fundamentals. STL data is used as input data and allows almost any kind of geometry. In general, a typical workflow for processing STL data is as follows: slicing volume data in order to gain contours that form 2D boarders, offsetting contours for a true to scale building process, filling of slices dependent on (offset) contours and generation of machine-code (g-code) that can be executed by the 3D printer in order to build an accurate and high-quality part. The model used in this approach is based on the droplets produced by the machine. A more detailed description of all the process-specific invidual steps from slicing up to g-code generation is presented within the scope of this paper. The continual development of custom-made algorithms based on process-specific models and parameters has resulted in the generation of g-code that could be executed on a 3D plastic polymer printer based on droplet generation for the first time. The resulting sample parts are very appealing. In conclusion, the results have shown that the whole production process can be a significant benefit especially for rapid prototyping of sample parts or spare parts.

Control of pressure is one of the most decisive parameters influencing the quality and reproducibility of products when dealing with plastics producing techniques such as injection molding, extrusion, and related techniques. For that purpose different types of pressure sensors for specific tasks come into action. Different tasks can be different working pressure ranges, static or dynamic pressure, working temperatures and requirements concerning the environment. Therefore different types of pressure sensors are commonly used which most often transform mechanical deformation into electrical signals and these in turn are converted into the value of pressure. This in turn can mean extensive effort for installation and insulation of the pressure sensors. An approach to design a pressure sensor based solely on its mechanical deformation is basic idea of the present work. The pressure sensor consists of a flexible element which is in fact a thin plate with a ram on its outer side and can be clamped easily at any desired area on a melt channel. When being applied to pressure the working pressure causes a deflection of the flexible element. Measuring this deflection and knowing the mechanical behavior of the flexible element allows the calculation of the value of pressure. To get to know to the mechanical behavior, especially the stiffness, of the flexible element a test rig was designed and refined. In the test rig as substitution of the pressure variable but defined load can be applied using a piezo-electrical actuator with integrated position sensor. Measuring the applied force using a force sensor and measuring the resulting deflection of the flexible element using a length gauge allows to calculate the stiffness of the flexible element. Regarding the flexible element as Kirchhoff plate a constant stiffness is expected and this could be proven taking measurements. When taking a look at the deflection of the piezo-electrical actuator and the flexible element there is a difference due to the elasticity of the test rig itself. When determining the stiffness of the test rig a non-constant stiffness was detected which was not expected. Reason for that is the non-constant stiffness of the used force sensor though stated other by the manufacturer. This could be proven substituting the force sensor with the flexible element. With that the flexible element showed to be appropriate to be used as force sensor with a constant stiffness.

The next step in minimally invasive surgery is the further reduction of incisions by surgery through natural orifices (NOTES) or one single artificial incision (Single-Port). However, physicians pointed out, that those procedures are only possible if new technologies will increase the dexterity of the instruments inside of the body. Especially the missing ability to manipulate tissue from two sides (triangulation), needs to be obtained. This article is about the development of different kinematics for a Multi Arm Snake-Like Robot to manipulate flexible endoscopic instruments at the tip of a flexible endoscope. By using Selective Laser Sintering (SLS) it is feasible to create various shapes and designs, custom made for different patients. We are using flexure hinges and compliant mechanisms to create defined movements in serial kinematic structures. In the experiments, the relation between different structures and the influence of the inserted flexible endoscopic instrument are compared. The proposed kinematics are able to manipulate flexible endoscopic instruments. That proves that SLS structures get more advances towards a use for a flexible Single-Port Multi Arm Snake-Like Robot.

In this manuscript we propose a robot with a novel kinematics and a novel imaging concept for a transcutaneous ultrasound probe. The underlying goal is to provide a laparoscopic surgeon intraoperative real-time images from within the surgical field without additional man power. The robot is manually controlled by the surgeon through a joystick console. The device is divided into two separate chambers. One is filled with pressurized water and incorporates an transcutaneous ultrasound probe. It is covered with a flexible silicone membrane that is in contact with the patient. The second cavity incorporates the kinematics and is filled with pressurized air. The kinematics has four degrees of freedom (two translational and two rotatory). In this paper, we provide the mathematical description for the direct as well as for the indirect kinematics along with a validation experiment.

Since rapid manufacturing (RM) technologies such as selective laser sintering (SLS) are on the edge to be used for the fabrication of fully functional components or even complete technical devices, we have to adapt the way we think of designing and assembling printable parts. RM makes it possible to realize complex geometrical structures with ease in small amounts at low cost. And it is possible to customize the geometry of e.g. a robot and simply print it according to the desired specifications. To make those technical possibilities available for any developer - no matter what technical background one has, from children to engineers, from hobby to professional use - it is important to automate basic design steps. In this paper we present a concept for the automated construction of gear boxes and our first step for achieving this goal: design algorithms for gear racks, spur gears and helical gears with internal and external involute toothing implemented in Matlab. The geometrical and mathematical description, the algorithms' concept and the creation of the STL files is explained. The gear wheels are designed to be compatible with all gear wheels according to ISO 2771.

In this article a new universal gripping adapter for a medical macro-micro telemanipulation system for the middle ear surgery is presented. The telemanipulation system should enable the surgeon to precisely manipulate tissue in interventions at the middle ear like the stapedotomy. The system proposed by Entsfellner et al. [1] contains of a joystick console, a robotic carrier system (macro-manipulator) with a robotic hand and three fingers, an active gripping adapter, a surgical micro-manipulator, and a microsurgical instrument. Using the adapter, no further modifications at the medical approved carrier system are necessary. The carrier system holds and guides the micro-manipulator with help of its robotic fingers. Both robotic systems can be sterilized using separate sterile foils. So the micro-manipulator can be attached to or removed from the carrier system at any time during an operation, and, if desired, exchanged with another device like, e.g., an endoscope. Furthermore, the control of the micro-manipulator by slightly moving the robotic fingers is possible and so no further cables or connections are necessary to transmit the control signals from the macro to the micro-manipulator. The surgeon can control the whole system telemanipulated by an OR (operating room) table mounted joystick console with touch display.

This paper presents a topological and dimensional kinematic synthesis methodology that can be used to constrain the movement of kinematic planar, spherical, and spatial revolute–revolute dyads (RR dyads). The approach is inspired by a subcategory of origami called rigid origami, which deals with highly overconstrained spatial deployable linkages. An example is the Miura-ori folding pattern used to deploy solar panels in space. In addition to this application, this linkage also provides an interesting way to constrain general RR dyads so that they perform a single DOF motion. Here, these mechanisms are called origami-guided RR chains, and computer aided design models (CAD) of the planar, spherical and spatial type are presented. The dimensional synthesis approach allows us to constrain consecutive links using R or C joints so that the links satisfy two arbitrarily predefined task positions. This leads to what we call the two-configuration synthesis of linkages, and we examine a concrete synthesis procedure for an origami-guided spatial RR chain, which is also built using rapid prototyping. The procedure actually combines the two-configuration synthesis approach with the synthesis of the spatial TS dyad, and the paper provides an outlook on further ways to apply the two-configuration synthesis and also to synthesize the origami-guided RR chains.

The objective of this work is twofold: firstly, to present the potential of CAD-based techniques with respect to implementing a user-friendly tool for systematic and efficient kinematic modeling and analysis of general assembly products, and secondly, to detail the significance of this approach for the development of a Robotic Assembly Language Planning Hierarchy (RALPH), a task-level automatic robot programming system. With the Product Assembly Modeler (PAM) as the environment for kinematic modeling, the geometric and topological information in the system's database is utilized to derive and solve the kinematic equations that characterize a mechanism. Spatial relationships play a central role in this process as they represent the kinematic constraints implied by the joints. The advantages of embedding kinematic analysis in PAM comprise the fleidbility of modeling open and closed loop mechanisms, the visual study of motion of a mechanism, and the evaluation of the integrity of the design. PAM also provides the geometric and topological data for RALPH to generate a process plan for robotic assembly. CAD-based kinematic modeling and analysis plays a key role with respect to automated programming of industrial robots due to the importance of the inverse kinematic problem.

In this presentation a practical look is taken at how the use of implant and electrode technology can be employed to create biological brains for robots, to enable human enhancement and to diminish the effects of certain neural illnesses. In all cases the end result is to increase the range of abilities of the recipients. An indication is given of a number of areas in which such technology has already had a profound effect, a key element being the need for a clear interface linking a biological brain directly with computer technology.

A novel experimentation platform, which is based on a piezoelectrically driven inkjet printhead and on a support plate, is presented. A huge number of fluids has to be ejected due to the large variety of possible applications for inkjet printheads. Each fluid with its special characteristics usually requires a redesign of the printhead to be able to be ejected. This inkjet printhead is manufactured in a batch process with rapid prototyping techniques in order to be able to be adapted to new boundary conditions in a time saving manner. The manufacturing time only amounts less than 30 minutes. The inkjet printhead is inserted into a support plate. Here, it is electrically as well as fluidically connected without any soldering or gluing processes. Heating elements, temperature as well as pressure sensors, and a fluid reservoir are integrated. The reproducibility of experiments is thereby given. Furthermore, printing fluids with solid-liquid phase transition is possible. The inkjet printhead can be changed within only one minute.

Flexible rhino endoscopes have been extensively used in many surgical and diagnostic procedures, such as in a rhinoscopy to examine the tumor or polyp in nasal cavity. However, the orientation of flexible endoscopes is only based on the endoscopic images, making its manipulation complex and requiring clinical experience. Therefore, we proposed a hand-held manipulator to motorize a standard flexible rhino endoscope. In this paper, we present a method to steer the motorized flexible rhino endoscope by using endoscopic images. A vision technique is used to extract the dark region from the image, which represents the distant inner space of nasal cavity and indicates the heading direction of the endoscope. Using this computer recognized target orientation, automatic endoscope steering becomes possible. Experiments were conducted in an anatomical model to simulate rhinoscopy. The results show that the image-guided steering is significantly faster than traditional manual steering and that the measured accuracy of the system fulfills current clinical requirements.

Intelligent control architecture of autonomous robot systems must be modular, scaleable, extendible, and adaptable to the available capacity of computer control systems. For the support of these properties, the concept of adaptive control structure, ACS, is presented in this paper. Experiments with small autonomous assembly robot show the successful use of ACS.

There were over 28.000 kidney tumor incidences in Germany in 2010. Minimally invasive (laparoscopic) removal of these tumors has become more and more popular. Intraoperative imaging during these procedures is mainly performed with videolaparoscopes. However, they provide only superficial images of the operating field increasing the challenge to remove the tumor. Conventional sonographic approaches may overcome this problem but require an additional assistant to guide the probe. To eliminate the need for an additional assistant, we developed a new robot with four degrees of freedom to motorize a sonographic probe. The robot can be installed in the operating room table and is directly controlled by the surgeon with telemanipulation. In experiments we showed that the accuracy of the kinematic is above the resolution of the sonographic probe.Copyright © 2012 by ASME

With the spread of endoscopic interventions the postoperative stress for patients has been reduced clearly. These interventions through natural orifices of the body (Natural orifice transluminal endoscopic surgery: NOTES) need miniaturized instruments with high precision, high range of motion and a high force load transmission. Our aim is to develop a mechatronic, single-port robotic system to guide and move flexible endoscopic instruments and optics inside the body. The system should be adapted to a flexible endoscope and consists of two flexible and actuated end-effectors that carry and manipulate flexible instruments. Due to the flexible end of the structure, laparoscopic single-port surgery through one incision and endoscopic surgery through a natural orifice would be possible. The concepts and prototypes were realized by selective laser sintering (SLS). One way to create flexible structures for a single use robot is to use universal joints assembled together in series. Next, selective laser sintering can now print these parts with the joints already assembled, in one part. There is no need for assembling or adhesive bonding. The final step is to replace the real joints of the cardan shafts with elastic joints. The proposed joints are made by the powder PA 2200 based on nylon. This basic powder is certificated as biocompatible according to ISO 10993-1. The challenge in this new field of printed medical robotics is to define a manufacturing process that enables you to design a part, create it by SLS and get it approved as a medical product.

When dealing with plastics producing techniques such as injection molding and extrusion control of pressure is a decisive parameter influencing the quality and reproducibility of plastics products. Different types of pressure sensors are commonly used which most often transform mechanical deformation into electrical signals and these in turn are converted into the value of pressure. In some cases separate pressure chambers might be necessary, often the pressure range is limited, and usage of electrical components lead to constraints concerning temperature range. This in turn means extensive effort for installation and insulation of the pressure sensors for example when you want to control the pressure at any desired area of the injection system. This work is based on an approach of using a flexible element and determining the pressure solely by its deformation. This eliminates thermal insulation and electromagnetic shielding. But concurrently this demands some knowledge concerning the mechanical behavior of the flexible element. To determine the mechanical behavior of the flexible element especially its stiffness different approaches have been taken into account. First one is to regard the flexible element as Kirchhoff plate. This analytic approach implies a constant bending stiffness which means a linear dependency between working pressure and resulting deflection. This could be confirmed evaluating measurement data that has been taken using a test rig specially designed for that task. In the test rig as substitution of the pressure a variable but defined load can be applied. When carrying out some measurements with one certain flexible element the influence of assembling and disassembling the test rig was obvious. Only when not changing the assembled test rig measurements have been reproducible. Main reason was the radial variance of applied load and the center of the flexible element. In order to solve that a test rig was redesigned including a centering device to guarantee load transmission happening always at the same point. Additionally influence of certain linkages in the test rig has been investigated. Combination of both leads to a more reliable and better test rig with higher reproducibility.