Digital Theses Archive


Tesi etd-04182021-112828

Type of thesis
E-mail address
Modular Soft Robotic Systems for Bioinspired Crawling Locomotion
Scientific disciplinary sector
Istituto di Biorobotica - BIOROBOTICS
relatore Prof. LASCHI, CECILIA
  • bioinspiration
  • crawling locomotion
  • modular robotics
  • soft actuator and sensing
  • soft robotic applications
  • variable stiffness
Exam session start date
The goal of this thesis is to explore how bioinspired soft robotics systems can be created using soft fluid-powered elastomeric bodies. This work is challenging in terms of design translation, fabrication and experimental validation of both single and multi-segment modular soft robotics systems consisting of actuators and sensors for crawling locomotion inspired by the invertebrate organisms such as "Snail and Earthworm". First, this thesis elaborates the process to develop various soft actuators with feasible functionalities. That is, novel approaches to design, fabrication, performance, and control are presented, along with extensive experimental evaluations using several soft robot prototypes. More specifically, three feasible actuators have been developed to achieve different soft machines to perform locomotion and manipulation morphologies, which are distinguished by their actuator designs, namely: pneunet, porous foam and hydrogel driven systems. In addition, three different rapid fabrication methods are investigated: Laser-cut molding and silicone casting, desktop fabrication and machining, and additive manufacturing. Second, this thesis explains the design and material fabrication of integrated soft sensors to understand the deformation of the robot and the environment (surface or terrain) through intrinsic proprioception and exteroception. More specifically, the sensorized foam actuator (SFA) with foam core acts as both actuator and proprioception sensor, which can detect direct actuation and passive deformation. For exteroception sensing, a special sensorized foot module (SFM) was developed based on a barometric MEMS pressure sensor encapsulated with an elastomer layer to understand anisotropic terrain and detect changes on the foot surface. Third, this thesis describes the locomotion principle of pedal waves in snails by a modular soft robot that is both self-contained and capable of fast modular body movements. In particular, the design, fabrication, control, and experiments of a soft crawling robot is detailed, with a focus on enabling the robot to perform a unique crawling locomotion inspired by the muscle motions observed in flat crawling sole of snail. The robot uses a hybrid body with an integrated actuator and sensor, described in Chapters 3 and 4. These are the components involved in the design and development of the very first modular snail-inspired robot. In addition, the robot has a novel fluidic actuation system that drives body motion and has all the subsystems of a conventional robot: power, actuation, sensing, and control. The crawling robot is designed to emulate various terrain reactions in addition to forward motion, as such maneuvers require rapid accelerations with continuous body movements. Using the modular robotic system we prove the biological hypothesis of pedal wave locomotion in snail with their different gait patterns. Finally, the new capabilities offered by this modular soft robotics system are validated through extensive physical experiments. These are (i) gait 1: normal speed locomotion, (ii) gait 2: rapid speed locomotion, method 1 (wave frequency doubles), (iii) gait 3: rapid speed locomotion, method 2 (wave length doubles), and (iv) difference in pedal wave locomotion on flat and sloped surfaces. Through these projects and others listed below, I have demonstrated the integrated fabrication solution for modular soft robots. In my dissertation, I present solutions demonstrated through scientific design, fabrication, testing, and evaluation of robot prototypes that utilize and demonstrate five key properties, such as. Intrinsic compliance: provided by passive stiffness and flexible components, Integrated design approach: provided by porous elastic foam that acts as both actuator and sensor, Exteroception: provided by a soft barometric pressure sensor to understand forces on anisotropic surfaces, Bioinspiration: provided by traveling wave locomotion towards a modular continuum soft robot, and Modular robot design: provided by independent control of modular segments to achieve motions performing complex task such as locomotion and manipulation. The combination of these key features would advance the field of soft robotics towards targeted applications such as inspection robots, medical and wearable robots.