Dexterous grippers: between simple industrial grippers and complex robotic hands

This thesis addresses the issue of introducing dexterity, namely the ability to manipulate objects in hand, into simple mechanical grippers. Among the many possibilities to give dexterity to a gripping device we opted to intervene at the finger-pad surface since it is the part of the end effector directly in contact with the object to be manipulated. The first contribution is the development of an under-actuated gripper with Active Surfaces on the inner side of the fingers which allow to in-hand manipulate the grasped objects. The gripper, named Velvet Fingers, was designed from the theoretical concepts, manufactured, assembled and then turned into an applicative scenario. A second main contribution of this thesis, carried out in collaboration with AASS Research Center, of the University of \"Orebro (Sweden), is a grasp execution routine using the Active Surfaces of the Velvet Fingers to achieve a robust power grasp starting from an initial fingertip grasp. This routine is very useful and effective in cluttered environment where an initial fingertip grasp is much more likely to be feasible than a bulky power grasp. The third main contribution is the development of a small gripper for small household objects such as cans, small bottles, little boxes, tennis balls etc. This gripper, named Velvet-II, is able to perform in-hand manipulation tasks, to elicit information from the grasped object, namely the contact point location and the components of the grasping forces and to detect incipient slippage between the gripper and the object. Within a collaboration with AASS Research Center the gripper has been employed on a robotic platform for autonomous picking and palletizing

Safe and effective physical human-robot interaction: Approaches to variable compliance via soft joints and soft grippers

The work described in this thesis focusses on designing and building two novel physical devices in a robotic arm structure. The arm is intended for human-robot interaction in the domestic assistive robotics area. The first device aims at helping to ensure the safety of the human user. It acts as a mechanical fuse and disconnects the robotic arm link from its motor in case of collision. The device behaves in a rigid manner in normal operational times and in a compliant manner in case of potentially harmful collisions: it relies on a variable compliance. The second device is the end-effector of the robotic arm. It is a novel grasping device that aims at accommodating varying object shapes. This is achieved by the structure of the grasping device that is a soft structure with a compliant and a rigid phase. Its completely soft structure is able to mould to the object's shape in the compliant phase, while the rigid phase allows holding the object in a stable way.In this study, variable compliance is defined as a physical structure's change from a compliant to a rigid behaviour and vice versa. Due to its versatility and effectiveness, variable compliance has become the founding block of the design of the two devices in the robot arm physical structure. The novelty of the employment of variable compliance in this thesis resides in its use in both rigid and soft devices in order to help ensure both safety and adaptable grasping in one integrated physical structure, the robot arm.The safety device has been designed, modelled, produced, tested and physically embedded in the robot arm system. Compared to previous work in this field, the feature described in this thesis' work has a major advantage: its torque threshold can be actively regulated depending on the operational situation. The threshold torque is best described by an exponential curve in the mathematical model while it is best fit by a second order equation in the experimental data. The mismatch is more considerable for high values of threshold torque. However, both curves reflect that threshold torque magnitude increases by increasing the setting of the device. Testing of both the passive decoupling and active threshold torque regulation show that both are successfully obtained. The second novel feature of the robot arm is the soft grasping device inspired by hydrostatic skeletons. Its ability to passively adapts to complex shapes objects, reduces the complexity of the grasping action control. This gripper is low-cost, soft, cable-driven and it features no stiff sections. Its versatility, variable compliance and stable grasp are shown in several experiments. A model of the forward kinematics of the system is derived from observation of its bending behaviour.Variable compliance has shown to be a very relevant principle for the design and implementation of a robotic arm aimed at safely interacting with human users and that can reduce grasp control complexity by passively adapting to the object's shape

Haptics: Science, Technology, Applications

This open access book constitutes the proceedings of the 13th International Conference on Human Haptic Sensing and Touch Enabled Computer Applications, EuroHaptics 2022, held in Hamburg, Germany, in May 2022. The 36 regular papers included in this book were carefully reviewed and selected from 129 submissions. They were organized in topical sections as follows: haptic science; haptic technology; and haptic applications

Soft pneumatic devices for blood circulation improvement

The research activity I am presenting in this thesis lies within the framework of a cooperation between the University of Cagliari (Applied Mechanics and Robotics lab, headed by professor Andrea Manuello Bertetto, and the research group of physicians referencing to professor Alberto Concu at the Laboratory of Sports Physiology, Department of Medical Sciences), and the Polytechnic of Turin (professor Carlo Ferraresi and his equipe at the Group of Automation and Robotics, Department of Mechanical and Aerospace Engineering) This research was also funded by the Italian Ministry of Research (MIUR – PRIN 2009). My activity has been mainly carried on at the Department of Mechanics, Robotics lab under the supervision of prof. Manuello; I have also spent one year at the Control Lab of the School of Electrical Engineering at Aalto University (Helsinki, Finland). The tests on the patients were taken at the Laboratory of Sports Physiology, Cagliari. I will be describing the design, development and testing of some soft pneumatic flexible devices meant to apply an intermittent massage and to restore blood circulation in lower limbs in order to improve cardiac output and wellness in general. The choice of the actuators, as well as the pneumatic circuits and air distribution system and PLC control patterns will be outlined. The trial run of the devices have been field--‐tested as soon a prototype was ready, so as to tune its features step--‐by--‐ step. I am also giving a characterization of a commercial thin force sensor after briefly reviewing some other type of thin pressure transducer. It has been used to gauge the contact pressure between the actuator and the subject’s skin in order to correlate the level of discomfort to the supply pressure, and to feed this value back to regulate the supply air flow. In order for the massage to be still effective without causing pain or distress or any cutoff to the blood flow, some control objective have been set, consisting in the regulation of the contact force so that it comes to the constant set point smoothly and its value holds constant until unloading occurs. The targets of such mechatronic devices range from paraplegic patients lacking of muscle tone because of their spinal cord damage, to elite endurance athletes needing a circulation booster when resting from practicing after serious injuries leading to bed rest. Encouraging results have been attained for both these two categories, based on the monitored hemodynamic variables

Climbing and Walking Robots

With the advancement of technology, new exciting approaches enable us to render mobile robotic systems more versatile, robust and cost-efficient. Some researchers combine climbing and walking techniques with a modular approach, a reconfigurable approach, or a swarm approach to realize novel prototypes as flexible mobile robotic platforms featuring all necessary locomotion capabilities. The purpose of this book is to provide an overview of the latest wide-range achievements in climbing and walking robotic technology to researchers, scientists, and engineers throughout the world. Different aspects including control simulation, locomotion realization, methodology, and system integration are presented from the scientific and from the technical point of view. This book consists of two main parts, one dealing with walking robots, the second with climbing robots. The content is also grouped by theoretical research and applicative realization. Every chapter offers a considerable amount of interesting and useful information

Using MapReduce Streaming for Distributed Life Simulation on the Cloud

Distributed software simulations are indispensable in the study of large-scale life models but often require the use of technically complex lower-level distributed computing frameworks, such as MPI. We propose to overcome the complexity challenge by applying the emerging MapReduce (MR) model to distributed life simulations and by running such simulations on the cloud. Technically, we design optimized MR streaming algorithms for discrete and continuous versions of Conway’s life according to a general MR streaming pattern. We chose life because it is simple enough as a testbed for MR’s applicability to a-life simulations and general enough to make our results applicable to various lattice-based a-life models. We implement and empirically evaluate our algorithms’ performance on Amazon’s Elastic MR cloud. Our experiments demonstrate that a single MR optimization technique called strip partitioning can reduce the execution time of continuous life simulations by 64%. To the best of our knowledge, we are the first to propose and evaluate MR streaming algorithms for lattice-based simulations. Our algorithms can serve as prototypes in the development of novel MR simulation algorithms for large-scale lattice-based a-life models.https://digitalcommons.chapman.edu/scs_books/1014/thumbnail.jp