Umberto Scarfogliero

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.

Design and Development of the Long-Jumping "Grillo" Mini Robot

This paper describes the design of a fast long-jumping robot conceived to move in unstructured environments through simple feed-forward control laws. Despite the apparent similarities with hopping, jumping dynamics is peculiar and involve non-trivial issues on actuation powering, energy saving and stability. The Grillo robot described here is a quadruped, 50-mm robot that weights about 15 grams and is suited for a long-jumping gait. Inspired by frog locomotion, a tiny motor load the springs connected to the hind limbs. At take-off, an escapement mechanism releases the loaded springs. This provides a peak power output that can exceed several times the maximum motor power. In this way, the actuation and energy systems can be significantly reduced in weight and size. On the other hand, passive dynamics is exploited by compliant forelegs, that let to partially recover the impact energy in their elastic recoil. Equipped with a 0.2W DC motor, the robot is dimensioned to achieve a forward speed of 1.5 m/s, which corresponds to about 30 body length per second.

A bioinspired concept for high efficiency locomotion in micro robots: the jumping Robot Grillo

This paper presents a bioinspired concept of locomotion for small autonomous robots. Scale effects in locomotion highly influence gait efficiency and in lightweight micro-robots jumping can be more energetically efficient than just walking or climbing. In addition, a jump can make the robot overcome obstacles and uneven terrains. Inspired by nature, the actuation of the proposed robot is entrusted to loaded springs. During the flight phase, energy from an electric micro-motor is collected in springs, while it is released by a click mechanism during take-off. In this way instant power delivered by rear legs (about 5 W) is much higher than the one provided by the motor (0.3 W). Passive compliant legs and low-power actuation result in light, efficient micro-robot, designed to have long autonomy for environment exploration and monitoring. In order to verify these assumptions, a quadruped prototype was developed, with two active rear limbs and passive elastic forelegs. Robot Grillo is 50 mm long and weighs about 10 grams. In conservative simulations the microrobot reaches a forward speed of 1.5 m/s, which corresponds to about 30 body length s-1

The green leafhopper, Cicadella viridis (Hemiptera, Auchenorrhyncha, Cicadellidae), jumps with near-constant acceleration

SUMMARY Jumping insects develop accelerations that can greatly exceed gravitational acceleration. Although several species have been analysed using different tools, ranging from a purely physical to a morpho-physiological approach, instantaneous dynamic and kinematic data concerning the jumping motion are lacking. This is mainly due to the difficulty in observing in detail events that occur in a few milliseconds. In this study, the behaviour of the green leafhopper, Cicadella viridis, was investigated during the take-off phase of the jump, through high-speed video recordings (8000 frames s−1). We demonstrate that C. viridis is able to maintain fairly constant acceleration during overall leg elongation. The force exerted at the foot–ground interface is nearly constant and differs from the force expected from other typical motion models. A biomechanical model was used to highlight that this ability relies on the morphology of C. viridis hind legs, which act as a motion converter with a variable transmission ratio and use the time-dependent musculo-elastic force to generate a nearly constant thrust at the body–ground interface. This modulation mechanism minimizes the risk of breaking the substrate thanks to the absence of force peaks. The results of this study are of broad relevance in different research fields ranging from biomechanics to robotics.

Advanced steps in biped robotics: innovative design and intuitive control through spring-damper actuator

This paper focuses on the study and design of an anthropomorphical light biped robot. The robot presents a total of twelve degree of freedom that permit it to perform a walk in a three dimensional space. Each joint resemble the functionalities of the human articulation and is moved by tendons connected with actuators located in the robots pelvis. We implemented and tested an innovative actuator that permits to set the joint stiffness in real time maintaining a simple position control paradigm. The controller is able to estimate the external load measuring the spring deflection and demonstrated to be particularly robust respect to system uncertainties, such as inertia value changes. Comparing the resulting control law with existing models we found several similarities with the equilibrium point theory.

Human-Oriented Biped Robot Design: Insights into the Development of a truly Anthropomorphic Leg

In this paper we present a human-oriented approach to the study of the biped gait for a humanoid robot. Starting from the analysis of the human lower-limbs, we figured out which features of the human legs are fundamental for a correct walking motion and can be adopted in the mechanical design of a humanoid robot. In particular we focus here on the knee, designed as a compliant human-like knee instead of a classical pin-joint. For the foot we tried to reproduce in a simple mechanical device the mobility and lightness of the human foot, which is very different from a flat surface and has a big impact on walking. We complete the presentation with considerations about the energy consumption of our humanoid design. In our approach the robot gains in adaptability and energetic efficiency, which are the most challenging issues for a biped robot.

Jumping mini-robot with bio-inspired legs

This paper presents a bio-inspired concept for an autonomous centimeter-scale robot for locomotion on un-even terrains with bionic legs. Our previous work, the jumping robot “GRILLO I” (Fig. 1A), is firstly introduced, as well as its limitations. For improving the performance of this prototype, we made biological observations on jumping insects by means of a high speed camera. It was found that the legs configuration let map muscle-like force into a constant force at feet-ground interface, which represents an optimum design for jumping. That gives us the bionic inspiration to redesign the legs that can reproduce the dynamic characteristics of insect jumping. Based on this idea, a new jumping robot prototype, GRILLO II (Fig. 1B), is then presented, as well as jumping details measured by the high speed camera and accelerometer.

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.

LARP, biped robotics conceived as human modelling

This paper presents a human-like control of an innovative biped robot. The robot presents a total of twelve degrees of freedom; each joint resemble the functionalities of the human articulation and is moved by tendons connected with an elastic actuator located in the robots pelvis. We implemented and tested an innovative control architecture (called elastic-reactive control) that permits to vary the joint stiffness in real time maintaining a simple position-control paradigm. The controller is able to estimate the external load measuring the spring deflection and demonstrated to be particularly robust respect to system uncertainties, such as inertia value changes. Comparing the resulting control law with existing models we found several similarities with the Equilibrium Point Theory.

Jumping mini-robot as a model of scale effects on legged locomotion

This paper presents a bio-inspired concept for an autonomous centimeter-scale robot for locomotion on un-even terrains. First, we discuss why legged locomotion can be more effective because of its high efficiency, low energy consumption and environmentally friendly operation. The choice of the optimal gait for the mini-robot is discussed according to its size. A small legged robot with some jumping mechanism can be efficient on compliant terrains, and this additional jumping function allows the robot to overcome obstacles several times higher than itself in a rough terrain. After that, a jumping robot named Grillo, our first prototype, is introduced. We also describe the electronic part of this robot, mainly focusing on control techniques exploited in the airborne phase.