Marco Piccigallo

Design of a Novel Bimanual Robotic System for Single-Port Laparoscopy

This paper presents the design and fabrication of Single-Port lapaRoscopy bImaNual roboT (SPRINT), a novel teleoperated robotic system for minimally invasive surgery. SPRINT, specifically designed for single-port laparoscopy, is a high-dexterity miniature robot, able to reproduce the movement of the hands of the surgeon, who controls the system through a master interface. It comprises two arms with six degrees of freedom (DOFs) that can be individually inserted and removed in a 30-mm-diameter umbilical access port. The system is designed to leave a central lumen free during operations, thus allowing the insertion of other laparoscopic tools. The four distal DOFs of each arm are actuated by on-board brushless dc motors, while the two proximal DOFs of the shoulder are actuated by external motors. The constraints generated by maximum size and power requirements led to the design of compact mechanisms for the actuation of the joints. The wrist is actuated by three motors hosted in the forearm, with a peculiar differential mechanism that allows us to have intersecting roll-pitch-roll axes. Preliminary tests and validations were performed ex vivo by surgeons on a first prototype of the system.

Variable Stiffness Actuators for Fast and Safe Motion Control

In this paper we propose Variable Stiffness actuation [1] as a viable mechanical/ control co-design approach for guaranteeing control performance for robot arms that are inherently safe to humans in their environment. A new actuator under development in our Lab is then proposed, which incorporate the possibility to vary transmission stiffness during motion execution, thus allowing substantial motion speed-up while maintaining low injury risk levels.

Physical human-robot interaction: Dependability, safety, and performance

Robots designed to share an environment with humans, such as e.g. in domestic or entertainment applications or in cooperative material-handling tasks, must fulfill different requirements from those typically met in industry. It is often the case, for instance, that accuracy requirements are less demanding. On the other hand, concerns of paramount importance are safety and dependability of the robot system. According to such difference in requirements, it can be expected that usage of conventional industrial arms for anthropic environments will be far from optimal. An approach to increase the safety level of robot arms interacting with humans consists in the introduction of compliance at the mechanical design level. In this paper we discuss the problem of achieving good performances in accuracy and promptness with a robot manipulator under the condition that safety is guaranteed throughout whole task execution. Intuitively, while a rigid and powerful structure of the arm would favor its performance, lightweight compliant structures are more suitable for safe operation. The quantitative analysis of the resulting design trade-off between safety and performance has a strong impact on how robot mechanisms and controllers should be designed for human- interactive applications. We discuss few different possible concepts for safely actuating joints, and focus on aspects related to the implementation of the mechanics and control of this new class of robots.

Lightweight Hand-held Robot for Laparoscopic Surgery

Some phases of laparoscopic interventions, such as suturing, require precise and dexterous movements that are difficult to perform by means of rigid instruments. Multi-DOF hand-held instruments and teleoperated systems have been developed to increase movement dexterity. In this paper, we present the design of a novel hand-held robotic instrument that can be operated by the surgeon with one hand only, while standing at the operating table and acting on a traditional laparoscopic instrument with the other hand. Its main advantages are the low weight, achieved by dislocating the motors and using a flexible transmission, and the possibility to switch end-effector, changing the instrument type according to the phase of the intervention. The instrument can be used easily and rapidly, since it does not require long or complex set-up procedures. We describe the instrument design, the development of the first prototype and compare it to rigid instruments in the ability to approach sutures at various angles.

Hand-held robotic instrument for dextrous laparoscopic interventions

Surgical instruments used in many types of minimally invasive procedures are rigid or only limitedly flexible. Some common tasks like suturing, require precise and dextrous movements that are difficult to perform by means of instruments with limited degrees of freedom (DOF).

Real-time control and evaluation of a teleoperated miniature arm for Single Port Laparoscopy

This paper presents the control architecture and the first performance evaluation results of a novel and highly-dexterous 18 degrees of freedom (DOF) miniature master/slave teleoperated robotic system called SPRINT (Single-Port la-paRoscopy bimaNual roboT). The system was evaluated in terms of positioning accuracy, repeatability, tracking error during local teleoperation and end-effector payload. Moreover, it was experimentally verified that the control architecture is real-time compliant at an operating frequency of 1 kHz and it is also reliable in terms of safety. The architecture accounts for cases when the robot is lead through singularities, and includes other safety mechanisms, such as supervision tasks and watchdog timers. Peliminary tests that were performed by surgeons in-vitro suggest that the SPRINT robot, along with its real-time control architecture, could become in the near future a reliable system in the field of Single Port Laparoscopy.

Comparison of control modes of a hand-held robot for laparoscopic surgery

Teleoperated robots for minimally invasive surgery make surgeons loose direct contact with the patient. We are developing a handheld, dexterous surgical robot that can be controlled with one hand only, while standing at the operating table. The instrument is composed of a master part (the handle) and a slave part (the tip). This work compares the performance of different control modes, i.e. different ways to map the degrees of freedom of the handle to those of the tip. We ask users to drive the tip along complex trajectories in a virtual environment, using the real master to drive a simulated slave, and assess their performance. Results show that, concerning time, users with no training in laparoscopy prefer a direct mapping of position and orientation, like in free hand motion. However, users trained in laparoscopy perform equally fast with our hand-held robot and, concerning precision, make a smaller number of errors.

Bioinspired Robotic Dual-Camera System for High-Resolution Vision

Due to the limited resolution of both cameras and displays, acuity of artificial vision systems is currently well below the human eye. Visual acuity, in cameras as well as in animal eyes, can be increased by making smaller receptors or bigger eyes. In some applications, the size of the camera is constrained, so alternative solutions must be sought. This paper presents a robotic dual-camera vision system whose design is inspired by the visual system of jumping spiders (Salticidae family). The system is composed of a telephoto camera whose field of view (FOV) can be moved within the larger FOV of a wide-angle camera and allows to form a high-resolution image, i.e., an image with the FOV of the wide-angle camera, yet having the same resolution as the telephoto camera. We describe the design of the robotic system, the direct and inverse kinematics, and the image processing algorithms that allow to build the high-resolution image. Images from experiments are presented, together with a discussion on sources of errors and possible solutions. The system is particularly useful for fixed-camera monitoring or teleoperation applications, such as remote surveillance and minimally invasive surgery. The system achieves seven times higher resolution than typical commercial endoscopes.

Stomach simulator for analysis and validation of surgical endoluminal robots

A testing environment that imitates gastric geometry and contractile activity is necessary to analyse and validate endoluminal surgical robotic devices developed for gastric pathologies. To achieve this goal, a silicone stomach model and a mechanical setup to simulate gastric contractile motion were designed and fabricated. The developed stomach simulator was validated and its usefulness was demonstrated by means of internal pressure measurements and self-assembly tests of mock-ups of capsule devices. The results demonstrated that the stomach simulator is helpful for quantitative evaluation of endoluminal robotic devices before in-vitro/in-vivo experiments.