Development of Rotary Variable Damping and Stiffness Magnetorheological Dampers and their Applications on Robotic Arms and Seat Suspensions

This thesis successfully expanded the idea of variable damping and stiffness (VSVD) from linear magnetorheological dampers (MR) to rotary magnetorheological dampers; and explored the applications of rotary MR dampers on the robotic arms and seat suspension. The idea of variable damping and stiffness has been proved to be able to reduce vibration to a large degree. Variable damping can reduce the vibration amplitude and variable stiffness can shift the natural frequency of the system from excitation and prevent resonance. Linear MR dampers with the capacity of variable damping and stiffness have been studied by researchers. However, Linear MR dampers usually require larger installation space than rotary MR dampers, and need more expensive MR fluids to fill in their chambers. Furthermore, rotary MR dampers are inherently more suitable than linear MR dampers in rotary motions like braking devices or robot joints. Hence, rotary MR dampers capable of simultaneously varying the damping and stiffness are very attractive to solve angular vibration problems. Out of this motivation, a rotary VSVD MR damper was designed, prototyped, with its feature of variable damping and stiffness verified by experimental property tests in this thesis. Its mathematical model was also built with the parameters identified. The experimental tests indicated that it has a 141.6% damping variation and 618.1% stiffness variation. This damper’s successful development paved the way for the applications of rotary MR dampers with the similar capability of variable damping and stiffness

Compliant polymeric actuators as robot drive units

A co-polymer made from Polyvinyl Alcohol and Polyacrylic Acid (PVA-PAA) has been synthesized to form new robotic actuation systems which use the contractile and variable compliance properties of this material. The stimulation of these fibres is studied (particularly chemical activation using acetone and water), as are the factors which influence the response, especially those relating to its performance as an artificial muscle.Mathematical models and simulations of the dynamics of the polymeric strips have been developed, permitting a thorough analysis of the performance determining parameters. Using these models a control strategy has been designed and implemented, with experimental results being obtained for a gripper powered by a flexor/extensor pair formed using these polymeric actuators.An investigation of a second property of the polymer, its variable compliance is also included. Use of this feature has lead to the design, construction and testing of a multi degree-of-freedom dextrous hand, which despite having only a single actuator, can exercise independent control over each joint

Development and Characterization of Velocity Workspaces for the Human Knee.

The knee joint is the most complex joint in the human body. A complete understanding of the physical behavior of the joint is essential for the prevention of injury and efficient treatment of infirmities of the knee. A kinematic model of the human knee including bone surfaces and four major ligaments was studied using techniques pioneered in robotic workspace analysis. The objective of this work was to develop and test methods for determining displacement and velocity workspaces for the model and investigate these workspaces. Data were collected from several sources using magnetic resonance imaging (MRI) and computed tomography (CT). Geometric data, including surface representations and ligament lengths and insertions, were extracted from the images to construct the kinematic model. Fixed orientation displacement workspaces for the tibia relative to the femur were computed using ANSI C programs and visualized using commercial personal computer graphics packages. Interpreting the constraints at a point on the fixed orientation displacement workspace, a corresponding velocity workspace was computed based on extended screw theory, implemented using MATLAB(TM), and visually interpreted by depicting basis elements. With the available data and immediate application of the displacement workspace analysis to clinical settings, fixed orientation displacement workspaces were found to hold the most promise. Significant findings of the velocity workspace analysis include the characterization of the velocity workspaces depending on the interaction of the underlying two-systems of the constraint set, an indication of the contributions from passive constraints to force closure of the joint, computational means to find potentially harmful motions within the model, and realistic motions predicted from solely geometric constraints. Geometric algebra was also investigated as an alternative method of representing the underlying mathematics of the computations with promising results. Recommendations for improving and continuing the research may be divided into three areas: the evolution of the knee model to allow a representation for cartilage and the menisci to be used in the workspace analysis, the integration of kinematic data with the workspace analysis, and the development of in vivo data collection methods to foster validation of the techniques outlined in this dissertation

Snake Robots for Surgical Applications: A Review

Although substantial advancements have been achieved in robot-assisted surgery, the blueprint to existing snake robotics predominantly focuses on the preliminary structural design, control, and human–robot interfaces, with features which have not been particularly explored in the literature. This paper aims to conduct a review of planning and operation concepts of hyper-redundant serpentine robots for surgical use, as well as any future challenges and solutions for better manipulation. Current researchers in the field of the manufacture and navigation of snake robots have faced issues, such as a low dexterity of the end-effectors around delicate organs, state estimation and the lack of depth perception on two-dimensional screens. A wide range of robots have been analysed, such as the i2Snake robot, inspiring the use of force and position feedback, visual servoing and augmented reality (AR). We present the types of actuation methods, robot kinematics, dynamics, sensing, and prospects of AR integration in snake robots, whilst addressing their shortcomings to facilitate the surgeon’s task. For a smoother gait control, validation and optimization algorithms such as deep learning databases are examined to mitigate redundancy in module linkage backlash and accidental self-collision. In essence, we aim to provide an outlook on robot configurations during motion by enhancing their material compositions within anatomical biocompatibility standards

Advances of Italian Machine Design

This 2028 Special Issue presents recent developments and achievements in the field of Mechanism and Machine Science coming from the Italian community with international collaborations and ranging from theoretical contributions to experimental and practical applications. It contains selected contributions that were accepted for presentation at the Second International Conference of IFToMM Italy, IFIT2018, that has been held in Cassino on 29 and 30 November 2018. This IFIT conference is the second event of a series that was established in 2016 by IFToMM Italy in Vicenza. IFIT was established to bring together researchers, industry professionals and students, from the Italian and the international community in an intimate, collegial and stimulating environment

Advanced Mobile Robotics: Volume 3

Mobile robotics is a challenging field with great potential. It covers disciplines including electrical engineering, mechanical engineering, computer science, cognitive science, and social science. It is essential to the design of automated robots, in combination with artificial intelligence, vision, and sensor technologies. Mobile robots are widely used for surveillance, guidance, transportation and entertainment tasks, as well as medical applications. This Special Issue intends to concentrate on recent developments concerning mobile robots and the research surrounding them to enhance studies on the fundamental problems observed in the robots. Various multidisciplinary approaches and integrative contributions including navigation, learning and adaptation, networked system, biologically inspired robots and cognitive methods are welcome contributions to this Special Issue, both from a research and an application perspective

Modellbasierte Kraftregelung einer mit pneumatischen Muskeln angetriebenen Parallelplatform

In the present work, a force and torque controlled Gough-Stewart type parallel platform driven by six actuator legs was developed and evaluated. Each actuator consists of a fluidic muscle which is combined with a prestressed coil spring in order to produce compressive as well as tensile forces. The platform shall be controlled such that arbitrary force functions can be simulated. Through geometric limit analyses, it was verified that the workspace of the mobile platform suffices to the required motion range. The model-based force control of each actuator uses an exponential approximation of the transient pressure responses. The six actuator control loops are embedded into the force and torque control of the parallel manipulator. The platform-control algorithm includes a kinetostatic platform model, which com-putes the corresponding required leg forces in order to achieve the target forces and torques at the end effector of the platform. It was shown that the target end-effector forces and torques, which do not pursue rapid changes, can be produced effectively with the developed parallel manipulator and the established platform control. The steady-state performance of the developed control algorithm sufficed to the requirements of a fine-tuned force and torque control. The manipulator was designed for its future application as a physical simulator of cervical spine motion for assessing effects of, e.g., implants, surgical treatments, etc.Die vorliegende Arbeit befasst sich mit der Entwicklung und Evaluierung einer kraftgeregelten Gough-Stewart Parallelplattform, die von sechs Aktoren angetrieben wird. Die Aktoren bestehen jeweils aus einem pneumatischen Muskel und einer vorgespannten Druckfeder. Die Plattform wird so geregelt, dass beliebige Kraft- und Momentenverläufe erstellt werden können. Durch die geometrische Analyse der Endlagen wurde verifiziert, dass der geforderte Arbeitsraum durch die Plattform erreicht werden kann. Jeder einzelne Aktor wird durch eine modellbasierte Kraftregelung kontrolliert, die unter anderem die Druckbeaufschlagung eines pneumatischen Muskels durch exponentielle Funktionen annähert. Die sechs Regelschleifen der Aktoren sind der Kraft- und Momentenregelung der Parallelplattform untergeordnet. Die Plattformregelung benutzt das kinetostatische Modell der Plattform und berechnet die jeweiligen Aktorkräfte, die zum Erreichen der aktuellen Sollkraft und Sollmomentes an der Plattform notwendig sind. Es wurde gezeigt, dass die geforderten Zielkräfte und Momente effektiv mit der kraftgeregelten Plattform produziert werden können und im stationären Bereich der Sprungantworten eine genaue Kraftregelung möglich ist. Die Parallelplattform wurde konzipiert für ihre zukünftige Anwendung als physikalischer Simulator der menschlichen Halswirbelsäule, unter anderem für die präoperative Analyse chirurgischer Eingriffe, Implantate etc

Remote-controlled ambidextrous robot hand actuated by pneumatic muscles: from feasibility study to design and control algorithms

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University LondonThis thesis relates to the development of the Ambidextrous Robot Hand engineered in Brunel University. Assigned to a robotic hand, the ambidextrous feature means that two different behaviours are accessible from a single robot hand, because of its fingers architecture which permits them to bend in both ways. On one hand, the robotic device can therefore behave as a right hand whereas, on another hand, it can behave as a left hand. The main contribution of this project is its ambidextrous feature, totally unique in robotics area. Moreover, the Ambidextrous Robot Hand is actuated by pneumatic artificial muscles (PAMs), which are not commonly used to drive robot hands. The type of the actuators consequently adds more originality to the project. The primary challenge is to reach an ambidextrous behaviour using PAMs designed to actuate non-ambidextrous robot hands. Thus, a feasibility study is carried out for this purpose. Investigating a number of mechanical possibilities, an ambidextrous design is reached with features almost identical for its right and left sides. A testbench is thereafter designed to investigate this possibility even further to design ambidextrous fingers using 3D printing and an asymmetrical tendons routing engineered to reduce the number of actuators. The Ambidextrous Robot Hand is connected to a remote control interface accessible from its website, which provides video streaming as feedback, to be eventually used as an online rehabilitation device. The secondary main challenge is to implement control algorithms on a robot hand with a range twice larger than others, with an asymmetrical tendons routing and actuated by nonlinear actuators. A number of control algorithms are therefore investigated to interact with the angular displacement of the fingers and the grasping abilities of the hand. Several solutions are found out, notably the implementations of a phasing plane switch control and a sliding-mode control, both specific to the architecture of the Ambidextrous Robot Hand. The implementation of these two algorithms on a robotic hand actuated by PAMs is almost as innovative as the ambidextrous design of the mechanical structure itself

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 296)

This bibliography lists 171 reports, articles and other documents introduced into the NASA scientific and technical information system in March, 1987

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