Tania K. Morimoto

[D81] Hapkit: An open-hardware haptic device for online education

Summary form only given. Courses involving a laboratory component are conspicuously missing from the recent upsurge in online courses, limiting student access to hands-on educational experiences. We present a low-cost, open-hardware haptic device, called Hapkit, designed to provide a hands-on laboratory experience in an introductory online haptics course. Hapkit is a one-degree-of-freedom kinesthetic haptic device that allows users to input motions and feel programmed forces. Based on previous haptic paddle designs, Hapkit consists of a motor, magneto-resistive sensor and rotating magnet, laser-cut acrylic structure, friction drive, force-sensitive resistor, and custom Arduino-based controller board. The CAD files, parts list and costs, assembly instructions, and sample software are posted at http://hapkit.stanford.edu so the public can both recreate Hapkit and modify its design. The corresponding online haptics course, piloted in Autumn 2013, will be available as a self-paced course at http://hapticsonline.stanford.edu. In this demonstration, conference attendees will be able to assemble and program Hapkits.

Surgeon design interface for patient-specific concentric tube robots

Concentric tube robots have potential for use in a wide variety of surgical procedures due to their small size, dexterity, and ability to move in highly curved paths. Unlike most existing clinical robots, the design of these robots can be developed and manufactured on a patient- and procedure-specific basis. The design of concentric tube robots typically requires significant computation and optimization, and it remains unclear how the surgeon should be involved. We propose to use a virtual reality-based design environment for surgeons to easily and intuitively visualize and design a set of concentric tube robots for a specific patient and procedure. In this paper, we describe a novel patient-specific design process in the context of the virtual reality interface. We also show a resulting concentric tube robot design, created by a pediatric urologist to access a kidney stone in a pediatric patient.

Design of 3-D Printed Concentric Tube Robots

Concentric tube surgical robots are minimally invasive devices with the advantages of snake-like reconfigurability, long and thin form factor, and placement of actuation outside the patients body. These robots can also be designed and manufactured to acquire targets in specific patients for treating specific diseases in a manner that minimizes invasiveness. We propose that concentric tube robots can be manufactured using 3-D printing technology on a patient- and procedure-specific basis. In this paper, we define the design requirements and manufacturing constraints for 3-D printed concentric tube robots and experimentally demonstrate the capabilities of these robots. While numerous 3-D printing technologies and materials can be used to create such robots, one successful example uses selective laser sintering to make an outer tube with a polyether block amide and uses stereolithography to make an inner tube with a polypropylene-like material. This enables a tube pair with precurvatures of 0.0775 and 0.0455 mm-1, which can withstand strains of 20% and 5.5% for the outer and inner tubes, respectively.

Robot Guided Sheaths (RoGS) for Percutaneous Access to the Pediatric Kidney: Patient-Specific Design and Preliminary Results

Robot-guided sheaths consisting of pre-curved tubes and steerable needles are proposed to provide surgical access to locations deep within the body. In comparison to current minimally invasive surgical robotic instruments, these sheaths are thinner, can move along more highly curved paths, and are potentially less expensive. This paper presents the patient-specific design of the pre-curved tube portion of a robot-guided sheath for access to a kidney stone; such a device could be used for delivery of an endoscope to fragment and remove the stone in a pediatric patient. First, feasible two-dimensional paths were determined considering workspace limitations, including avoidance of the ribs and lung, and minimizing collateral damage to surrounding tissue by leveraging the curvatures of the sheaths. Second, building on prior work in concentric-tube robot mechanics, the mechanical interaction of a two-element sheath was modeled and the resulting kinematics was demonstrated to achieve a feasible path in simulation. In addition, as a first step toward three-dimensional planning, patient-specific CT data was used to reconstruct a three-dimensional model of the area of interest.Copyright

Series pneumatic artificial muscles (sPAMs) and application to a soft continuum robot

We describe a new series pneumatic artificial muscle (sPAM) and its application as an actuator for a soft continuum robot. The robot consists of three sPAMs arranged radially around a tubular pneumatic backbone. Analogous to tendons, the sPAMs exert a tension force on the robots pneumatic backbone, causing bending that is approximately constant curvature. Unlike a traditional tendon driven continuum robot, the robot is entirely soft and contains no hard components, making it safer for human interaction. Models of both the sPAM and soft continuum robot kinematics are presented and experimentally verified. We found a mean position accuracy of 5.5 cm for predicting the end-effector position of a 42 cm long robot with the kinematic model. Finally, closed-loop control is demonstrated using an eye-in-hand visual servo control law which provides a simple interface for operation by a human. The soft continuum robot with closed-loop control was found to have a step-response rise time and settling time of less than two seconds.

Toward the Design of Personalized Continuum Surgical Robots

Robot-assisted minimally invasive surgical systems enable procedures with reduced pain, recovery time, and scarring compared to traditional surgery. While these improvements benefit a large number of patients, safe access to diseased sites is not always possible for specialized patient groups, including pediatric patients, due to their anatomical differences. We propose a patient-specific design paradigm that leverages the surgeon’s expertise to design and fabricate robots based on preoperative medical images. The components of the patient-specific robot design process are a virtual reality design interface enabling the surgeon to design patient-specific tools, 3-D printing of these tools with a biodegradable polyester, and an actuation and control system for deployment. The designed robot is a concentric tube robot, a type of continuum robot constructed from precurved, elastic, nesting tubes. We demonstrate the overall patient-specific design workflow, from preoperative images to physical implementation, for an example clinical scenario: nonlinear renal access to a pediatric kidney. We also measure the system’s behavior as it is deployed through real and artificial tissue. System integration and successful benchtop experiments in ex vivo liver and in a phantom patient model demonstrate the feasibility of using a patient-specific design workflow to plan, fabricate, and deploy personalized, flexible continuum robots.

PD42-12 DESIGN, FABRICATION, AND TESTING OF PATIENT-SPECIFIC CONCENTRIC TUBE ROBOTS FOR NONLINEAR RENAL ACCESS AND MASS ABLATION

INTRODUCTION AND OBJECTIVES: To address limitations of current commercial, mass-produced robot-assisted surgical systems widely used in urology and other surgical specialties, we propose to develop patientand procedure-specific dexterous robots. Our focus is on a class of continuum robots known as concentric tube robots, which are comprised of a series of hollow, nesting, precurved tubes that are individually inserted and rotated with respect to one another in order to change the shape of the overall robot. We aim to develop a method for designing, fabricating, and driving a patient-specific concentric tube robot as an alternative paradigm to traditional robotic surgical systems in order to improve procedures for specialized patient groups. As a test case we focus here on nonlinear renal access, for example, subcostal punctures into the upper pole calyces of the kidney to ablate an endophytic renal mass. METHODS: To enable patient-specific design of these robots, a virtual-reality based interface was developed. The interface leverages the expertise of a surgeon by immersing him or her in a 3-D virtual environment that includes a reconstructed model of the patient’s thoracoabdominal anatomy based on CT scans. Once the surgeon designs the set of concentric tubes, we generate a 3-D model and subsequently 3-D print each tube using a biocompatible polycaprolactone (PCL) filament. The printed tubes are then nested one inside the next and attached to the compact, modular actuation and control system we built for driving these robots. The surgeon controls the movement of the concentric tube robot through a teleoperation control scheme. RESULTS: A board-certified urologist performed a preliminary test of the entire system. After an explanation of the interface and its features, the surgeon was immersed in the virtual environment (using 3D reconstructions of an actual patient’s upper abdominal anatomy, including kidney and an associated upper caliceal lesion) and tasked with designing a set of tubes to access the lesion. Based on his intuition and expertise, he designed three different sets, which were then 3-D printed with PCL. The surgeon then performed mock procedures by driving each concentric tube robot into a phantom model of the patient’s thoracoabdominal anatomy in order to reach the lesion. The lesion was generated using a thermochromic dye which changes color when heated. Once the target was reached, a radiofrequency ablation (RFA) probe was passed through the concentric tube robot and successful ablation confirmed by color change of the lesion. CONCLUSIONS: This work proposes a framework for integration of the surgeon into design and fabrication of a set of patientand procedurespecific concentric tubes. Preliminary results demonstrate that a surgeon can use the interface to design a concentric tube robot to access and ablate renal lesions by RFA.