Giuseppe Pernorio

A SMA actuated artificial earthworm

This paper presents the design and development of a microrobot which aims to replicate the locomotion principle of earthworms. The undulatory locomotion of living earthworms has been investigated deeply from the biological point of view, but attempts at replication of earthworm models in real size are limited. The authors have designed an artificial earthworm with four modules which can be driven independently according to defined undulatory patterns with a typical frequency of 0.5 Hz. Each module is actuated by one or more SMA springs whose configuration has been designed in order to limit wiring problems and optimize working frequency. The robot is covered by a shaped silicone material which can be used as a platform to insert tiny legs for obtaining differential friction conditions. Preliminary tests demonstrate that the earthworm prototypes can move with a speed of 0.22 mm/s, thus approximating the behavior of biological earthworms.

Shape memory alloy clamping devices of a capsule for monitoring tasks in the gastrointestinal tract

This paper describes the development of an active clamping mechanism to be integrated into a swallowable pill for the diagnosis of the gastrointestinal (GI) tract. The clamping system allows us to stop the pill at desired sites of the GI tract for long monitoring purposes. After discussing the major technical constraints, the design of the core component, i.e. the gripper, based on FEA (finite element analysis), is illustrated as well as its fabrication process. Symmetric and asymmetric gripper designs are described. The actuation is provided by shape memory alloys (SMA), and it is driven by a dedicated electrical interface. Then the working prototypes have been tested in vitro: for both kinds of grippers a pull-back force up to 0.6 N has been measured. A preliminary theoretical model for the gripper has been derived and compared to the experimental results.

Locomotion of a legged capsule in the gastrointestinal tract: theoretical study and preliminary technological results

This work illustrates the analysis of locomotion in the gastrointestinal tract obtainable by a legged capsule for diagnostic and therapeutic purposes. A preliminary simulation of the legged locomotion onto slippery and deformable substrates has been performed and -simultaneously- mechanisms for on board actuation of the legs have been developed and tested. Moreover, an engineering translation of medical needs in endoscopy is presented, with some ad hoc solutions for improving diagnostic capabilities.

Design, Fabrication and Performances of a Biomimetic Robotic Earthworm

This paper presents the design and development of a microrobot which aims to replicate the locomotion principle of earthworms. By investigating the biological field, the authors developed artificial earthworms by mimicking the structures and locomotion principles of real ones. Prototypes with or without micro-legs (which affect the locomotion performance) have been developed. Each prototype has four modules which can be driven independently according to defined undulatory patterns with a typical frequency of 0.5 Hz. Each module is actuated by one or more SMA springs whose configuration has been designed in order to limit the wiring problems and optimizing working frequency. The robots are covered by shaped silicone material which can be used as a platform to insert tiny legs for obtaining differential friction conditions. Preliminary tests demonstrate that the maximum speed of earthworm prototypes can reach 0.22 mm/s without micro-legs and 2.5 mm/s with micro-legs, thus approximating the behavior of biological earthworms

A Novel SMA-Based Actuator for a Legged Endoscopic Capsule

This paper describes the design, modelling and fabrication of a shape memory alloy micro-actuation concept for application in an endoscopic capsule. The constraints of the actuators are discussed based on the planned integration in a swallowable capsule and a preliminary concept of a legged system with shape memory alloy actuation is presented and tested. Based on the preliminary results, a modelling of the system is given in order to optimize the actuator design in terms on length, diameter, angle and force. Thus, a new high performance prototype is developed and characterized, thus verifying the theoretical model

Development of a legged capsule for the gastrointestinal tract: an experimental set-up

The experimental study reported in this paper illustrates the development of a legged locomotion system for autonomous medical microrobots with the final goal to perform gastrointestinal (GI) diagnosis by minimally invasive endoscopy. An active teleoperated diagnostic capsule should be able to adapt its gait to changing gut diameters and vary its patterns to turn, rotate or stop based on the encountered pathologies. Therefore, in order to obtain propulsion in the GI tract, locomotion effectiveness, adaptability and dexterity are required. A biomechanical integrative approach has been followed, based on the investigation of biological legged locomotion models, with the aim to derive design rules for a legged artificial system. Because of the locomotion parameters which are critical for obtaining an effective locomotion are a lot and they are often difficult to be modelled and simulated, an experimental set-up has been developed in order to accomplish the problem analysis before designing the final endoscopic wireless capsule. An hexapod device with a sprawled insect-like posture has been developed. The device is provided with six superelastic legs, which are actuated by push-pull cables moved by traditional DC servomotors. Preliminary tests on porcine bowel and on latex GI simulators have been performed on a dedicated and sensorized design of a future test-bench, thus allowing to derive important guidelines for the wireless capsule development and for implementing the best gait

Clamping Tools of a Capsule for Monitoring the Gastrointestinal Tract Problem Analysis and Preliminary Technological Activity

This paper describes the development of an active clamping mechanism to be integrated into a swallowable pill for the diagnosis of the gastrointestinal (GI) tract. The clamping system allows to stop the pill in desired sites of the GI tract for long monitoring purposes. After discussing the major technical constraints, the design of the clamping system, based on FEA (Finite Element Analysis), is illustrated as well as its fabrication process. The clamping unit is actuated exploiting Shape Memory Alloys (SMA), in wires and spring configuration, and it is driven by a dedicated electrical interface. A fine tuning has been performed in order to limit the power consumption. Then a working prototype is fabricated and preliminarily tested, pointing out a capability of the grasping system over 40 g.