Advances in Bio-Inspired Robots

This book covers three major topics, specifically Biomimetic Robot Design, Mechanical System Design from Bio-Inspiration, and Bio-Inspired Analysis on A Mechanical System. The Biomimetic Robot Design part introduces research on flexible jumping robots, snake robots, and small flying robots, while the Mechanical System Design from Bio-Inspiration part introduces Bioinspired Divide-and-Conquer Design Methodology, Modular Cable-Driven Human-Like Robotic Arm andWall-Climbing Robot. Finally, in the Bio-Inspired Analysis on A Mechanical System part, research contents on the control strategy of Surgical Assistant Robot, modeling of Underwater Thruster, and optimization of Humanoid Robot are introduced

Robot Assisted Shoulder Rehabilitation: Biomechanical Modelling, Design and Performance Evaluation

The upper limb rehabilitation robots have made it possible to improve the motor recovery in stroke survivors while reducing the burden on physical therapists. Compared to manual arm training, robot-supported training can be more intensive, of longer duration, repetitive and task-oriented. To be aligned with the most biomechanically complex joint of human body, the shoulder, specific considerations have to be made in the design of robotic shoulder exoskeletons. It is important to assist all shoulder degrees-of-freedom (DOFs) when implementing robotic exoskeletons for rehabilitation purposes to increase the range of motion (ROM) and avoid any joint axes misalignments between the robot and human’s shoulder that cause undesirable interaction forces and discomfort to the user. The main objective of this work is to design a safe and a robotic exoskeleton for shoulder rehabilitation with physiologically correct movements, lightweight modules, self-alignment characteristics and large workspace. To achieve this goal a comprehensive review of the existing shoulder rehabilitation exoskeletons is conducted first to outline their main advantages and disadvantages, drawbacks and limitations. The research has then focused on biomechanics of the human shoulder which is studied in detail using robotic analysis techniques, i.e. the human shoulder is modelled as a mechanism. The coupled constrained structure of the robotic exoskeleton connected to a human shoulder is considered as a hybrid human-robot mechanism to solve the problem of joint axes misalignments. Finally, a real-scale prototype of the robotic shoulder rehabilitation exoskeleton was built to test its operation and its ability for shoulder rehabilitation

Design and Analysis of a Cable-Driven Test Apparatus for Flapping-Flight Research

The biology, physiology, kinematics, and aerodynamics of insect flight have been a longstanding fascination for biologists and engineers. The former three are easily obtained through the observation of the organic species. The latter though, is very difficult to study in this fashion. In many cases, aerodynamic forces and fluid-body interactions can be simulated with computational fluid dynamics; another option is to use dynamically-scaled, experimental set-ups to measure physically these values. An archetypal, experimental set-up may include one or two scaled wings, where each wing is actuated to achieve upwards of three degrees of freedom. The three degrees of freedom correspond biologically to the stroke, deviation, and rotation motions of real insects. The wing modules may be fixed to rotate about a central, fourth axis, mimicking the insect body rotation. Alternatively, the wing modules can be fixed to translate in one direction, copying the forward flight pattern of an insect. These experiments usually are performed in a tank of mineral oil, seeded to highlight the fluid\u27s movement. Unfortunately, the current state of experimental apparatuses limit the number and complexity of studiable flight patterns. The goal is to use a subset of robotics called cable-driven parallel manipulators to improve upon and expand the capabilities of these apparatuses. For these robots, rigid links are replaced with tensioned cables and actuated via electric motors. Each cable attaches to the central manipulator platform, similar to other parallel manipulators. Some advantages of a cable-driven design are large position workspaces, low inertia, high manipulator dynamics, large strength-to-weight ratio, and no actuator-error stack-up. Cable manipulators have been researched in the lab and have been deployed commercially, such as at professional sports stadiums. The manipulator uses a standard cuboid frame, with eight winches actuating eight cables. The manipulator platform is a scaled insect body, with each wing capable of three degrees of freedom, and an optimized attachment frame for the cables. The manipulator\u27s workspace for six degrees of freedom was derived from previous works and simulated in MathWorks\u27 MATLAB for a variety of parameterizations. The lead design incorporates a novel, new cable configuration for realizing greater rotational capability over standard cable-driven manipulators. While a standard, Straight cable configuration allows for large translation but almost no rotation, the new Twist cable configuration provides a smaller yet spread out workspace that is sustainable through singular rotations up to at least 45°, as well as simultaneous rotations about multiple axes. Optimal trends for the attachment frame are discerned from comparing a multitude of size permutations for singular rotations. No one attachment frame holds equal rotational potential about all three axes; however, the strengths and weaknesses of an attachment frame easily are adaptable based on the proposed insect maneuver. To showcase the versatility of the apparatus with a 6 in × 2 in × 4 in attachment frame, four different flight maneuvers are analyzed. The first two case studies prove the cable-driven apparatus can combine the individual functions of existing experimental apparatuses: MATLAB simulations show the device can perform a stationary 116° yaw rotation and separately can translate the end effector 32 in along one axis. A third case study investigates a previously published work on an evasive pitching maneuver from a hawkmoth. In the original study, the normally six-degree-of-freedom movement was distilled down to only one-dimensional translation and pitch rotation, such that it could be replicated in the lab. Using the cable-driven apparatus though, it is possible instead to reproduce the generalized, six-degree-of-freedom maneuver. Finally, a conceptual flight pattern is created to demonstrate the unique advantages of the cable-driven apparatus. The flight path models a pitched dive into a banked quarter turn, with a pitched climb upon exiting the turn. The equal necessity and coupling of all degrees of freedom for this maneuver means it cannot be performed on current experimental apparatuses, except for the cable-driven apparatus. This new cable-driven test apparatus, with its unique design and modifications, would improve the capabilities for experimental studies and provide the most realistic set-up for flapping-flight research

Reconfigurable cable driven parallel mechanism

Due to the fast growth in industry and in order to reduce manufacturing budget, increase the quality of products and increase the accuracy of manufactured products in addition to assure the safety of workers, people relied on mechanisms for such purposes. Recently, cable driven parallel mechanisms (CDPMs) have attracted much attention due to their many advantages over conventional parallel mechanisms, such as the significantly large workspace and the dynamics capacity. In addition, it has lower mass compared to other parallel mechanisms because of its negligible mass cables compared to the rigid links. In many applications it is required that human interact with machines and robots to achieve tasks precisely and accurately. Therefore, a new domain of scientific research has been introduced, that is human robot interaction, where operators can share the same workspace with robots and machines such as cable driven mechanisms. One of the main requirements due to this interaction that robots should respond to human actions in accurate, harmless way. In addition, the trajectory of the end effector is coming now from the operator and it is very essential that the initial trajectory is kept unchanged to perform tasks such assembly, operating or pick and place while avoiding the cables to interfere with each other or collide with the operator. Accordingly, many issues have been raised such as control, vibrations and stability due the contact between human and robot. Also, one of the most important issues is to guarantee collision free space (to avoid collision between cables and operator and to avoid collisions between cables itself). The aim of this research project is to model, design, analysis and implement reconfigurable six degrees of freedom parallel mechanism driven by eight cables. The main contribution of this work will be as follow. First, develop a nonlinear model and solve the forward and inverse kinematics issue of a fully constrained CDPM given that the attachment points on the rails are moving vertically (conventional cable driven mechanisms have fixed attachment points on the rails) while controlling the cable lengths. Second, the new idea of reconfiguration is then used to avoid interference between cables and between cables and operator limbs in real time by moving one cable’s attachment point on the frame to increase the shortest distance between them while keeping the trajectory of the end effector unchanged. Third, the new proposed approach was tested by creating a simulated intended cable-cable and cable-human interference trajectory, hence detecting and avoiding cable-cable and cable-human collision using the proposed real time reconfiguration while maintaining the initial end effector trajectory. Fourth, study the effect of relocating the attachment points on the constant-orientation wrench feasible workspace of the CDPM. En raison de la croissance de la demande de produits personnalisés et de la nécessité de réduire les coûts de fabrication tout en augmentant la qualité des produits et en augmentant la personnalisation des produits fabriqués en plus d'assurer la sécurité des travailleurs, les concepteurs se sont appuyés sur des mécanismes robotiques afin d’atteindre ces objectifs. Récemment, les mécanismes parallèles entraînés par câble (MPEC) ont attiré beaucoup d'attention en raison de leurs nombreux avantages par rapport aux mécanismes parallèles conventionnels, tels que l'espace de travail considérablement grand et la capacité dynamique. De plus, ce mécanisme a une masse plus faible par rapport à d'autres mécanismes parallèles en raison de ses câbles de masse négligeable comparativement aux liens rigides. Dans de nombreuses applications, il est nécessaire que l’humain interagisse avec les machines et les robots pour réaliser des tâches avec précision et rapidité. Par conséquent, un nouveau domaine de recherche scientifique a été introduit, à savoir l'interaction humain-robot, où les opérateurs peuvent partager le même espace de travail avec des robots et des machines telles que les mécanismes entraînés par des câbles. L'une des principales exigences en raison de cette interaction que les robots doivent répondre aux actions humaines d'une manière sécuritaire et collaboratif. En conséquence, de nombreux problèmes ont été soulevés tels que la commande et la stabilité dues au contact physique entre l’humain et le robot. Aussi, l'un des enjeux les plus importants est de garantir un espace sans collision (pour éviter les collisions entre des câbles et un opérateur et éviter les collisions entre les câbles entre eux). Le but de ce projet de recherche est de modéliser, concevoir, analyser et mettre en œuvre un mécanisme parallèle reconfigurable à six degrés de liberté entraîné par huit câbles. La principale contribution de ces travaux de recherche est de développer un modèle non linéaire et résolvez le problème de cinématique direct et inverse d'un CDPM entièrement contraint étant donné que les points d'attache sur les rails se déplacent verticalement (les mécanismes entraînés par des câbles conventionnels ont des points d'attache fixes sur les rails) tout en contrôlant les longueurs des câbles. Dans une deuxième étape, l’idée de la reconfiguration est ensuite utilisée pour éviter les interférences entre les câbles et entre les câbles et les membres d’un opérateur en temps réel en déplaçant un point de fixation du câble sur le cadre pour augmenter la distance la plus courte entre eux tout en gardant la trajectoire de l'effecteur terminal inchangée. Troisièmement, la nouvelle approche proposée a été évaluée et testée en créant une trajectoire d'interférence câble-câble et câble-humain simulée, détectant et évitant ainsi les collisions câble-câble et câble-humain en utilisant la reconfiguration en temps réel proposée tout en conservant la trajectoire effectrice finale. Enfin la dernière étape des travaux de recherche consiste à étudiez l'effet du déplacement des points d'attache sur l'espace de travail réalisable du CDPM

Dynamically Feasible Trajectories of Fully-Constrained Cable-Suspended Parallel Robots

Cable-Driven Parallel Robots employ multiple cables, whose lengths are controlled by winches, to move an end-effector (EE). In addition to the advantages of other parallel robots, such as low moving inertias and the potential for high dynamics, they also provide specific advantages, such as large workspaces and lower costs. Thus, over the last 30 years, they have been the object of academic research; also, they are being employed in industrial applications. The main issue with cable actuation is its unilaterality, as cables must remain in tension: if they become slack, there is a risk of losing control of the EE's pose. This complicates the control of cable-driven robots and is among the most studied topics in this field. Most previous works resort to extra cables or rigid elements pushing on the EE to guarantee that cables remain taut, but this complicates robot design. An alternative is to use the gravitational and inertial forces acting on the EE to keep cables in tension. This thesis shows that the robot's workspace can be greatly increased, by considering two model architectures. Moreover, practical limits to the feasibility of a motion, such as singularities of the kinematic chain and interference between cables, are considered. Even if a motion is feasible, there is no guarantee that it can be performed with an acceptable precision in the end-effector's pose, due to the inevitable errors in the positioning of the actuators and the elastic deflections of the structure. Therefore, a set of indexes are evaluated to measure the sensitivity of the end-effector's pose to actuation errors. Finally, the stiffness of one of the two architectures is modeled and indexes to measure the global compliance of the robot due to the elasticity of the cables are presented.I robot paralleli a cavi impiegano cavi, la cui lunghezza è controllata da argani, per muovere un elemento terminale o end-effector (EE). Oltre ai vantaggi degli altri robot paralleli, come basse inerzie in movimento e la possibilità di raggiungere velocità e accelerazioni elevate, possono anche fornire vantaggi specifici, come ampi spazi di lavoro e costi inferiori. Pertanto, negli ultimi 30 anni, questi robot sono stati oggetto di ricerche accademiche e stanno trovando applicazione anche in campo industriale. Il problema principale dell'azionamento mediante cavi è che è unilaterale, poiché i cavi possono essere tesi ma non compressi: quando diventano laschi, si rischia di perdere il controllo della posa dell'EE. Questo complica il controllo dei robot ed è uno dei temi più studiati nel settore. Gli studi compiuti sinora ricorrono prevalentemente a cavi addizionali o a elementi rigidi che spingono sull'EE per garantire che i cavi rimangano tesi, ma questo complica la progettazione dei robot. Un'alternativa è sfruttare le forze gravitazionali e inerziali che agiscono sull'EE per mantenere i cavi in tensione. Questa tesi dimostra che, in questo caso, lo spazio di lavoro del robot può essere notevolmente aumentato, applicando questo concetto a due architetture modello. Inoltre, vengono considerati i limiti imposti all'effettiva realizzabilità di un movimento, come le singolarità della catena cinematica e l'interferenza tra i cavi. Anche se un movimento è fattibile, non è garantito che si possa eseguire con precisione accettabile, a causa degli inevitabili errori di posizionamento degli attuatori e delle deformazioni elastiche della struttura. Si valutano quindi alcuni indici per misurare la sensibilità della posizione dell'elemento terminale agli errori di azionamento. Infine, è modellata la rigidezza di una delle due architetture proposte e sono presentati indici per misurare la cedevolezza globale del robot dovuta all'elasticità dei cavi

A Series-Elastic Robot for Back-Pain Rehabilitation

Robotics research has been broadly expanding into various fields during the past decades. It is widely spread and best known for solving many technical necessities in different fields. With the rise of the industrial revolution, it upgraded many factories to use industrial robots to prevent the human operator from dangerous and hazardous tasks. The rapid development of application fields and their complexity have inspired researchers in the robotics community to find innovative solutions to meet the new desired requirements of the field. Currently, the creation of new needs outside the traditional industrial robots are demanding robots to attend to the new market and to assist humans in meeting their daily social needs (i.e., agriculture, construction, cleaning.). The future integration of robots into other types of production processes, added new requirements that require more safety, flexibility, and intelligence in robots. Areas of robotics has evolved into various fields. This dissertation addresses robotics research in four different areas: rehabilitation robots, biologically inspired robots, optimization techniques, and neural network implementation. Although these four areas may seem different from each other, they share some research topics and applications

Modeling of Force and Motion Transmission in Tendon-Driven Surgical Robots

Tendon-based transmission is a common approach for transferring motion and forces in surgical robots. In spite of design simplicity and compactness that comes with the tendon drives, there exists a number of issues associated with the tendon-based transmission. In particular, the elasticity of the tendons and the frictional interaction between the tendon and the routing result in substantially nonlinear behavior. Also, in surgical applications, the distal joints of the robot and instruments cannot be sensorized in most cases due to technical limitations. Therefore, direct measurement of forces and use of feedback motion/force control for compensation of uncertainties in tendon-based motion and force transmission are not possible. However, force/motion estimation and control in tendon-based robots are important in view of the need for haptic feedback in robotic surgery and growing interest in automatizing common surgical tasks. One possible solution to the above-described problem is the development of mathematical models for tendon-based force and motion transmission that can be used for estimation and control purposes. This thesis provides analysis of force and motion transmission in tendon-pulley based surgical robots and addresses various aspects of the transmission modeling problem. Due to similarities between the quasi-static hysteretic behavior of a tendon-pulley based da Vinci® instrument and that of a typical tendon-sheath mechanism, a distributed friction approach for modeling the force transmission in the instrument is developed. The approach is extended to derive a formula for the apparent stiffness of the instrument. Consequently, a method is developed that uses the formula for apparent stiffness of the instrument to determine the stiffness distribution of the tissue palpated. The force transmission hysteresis is further investigated from a phenomenological point of view. It is shown that a classic Preisach hysteresis model can accurately describe the quasi-static input-output force transmission behavior of the da Vinci® instrument. Also, in order to describe the distributed friction effect in tendon-pulley mechanisms, the creep theory from belt mechanics is adopted for the robotic applications. As a result, a novel motion transmission model is suggested for tendon-pulley mechanisms. The developed model is of pseudo-kinematic type as it relates the output displacement to both the input displacement and the input force. The model is subsequently used for position control of the tip of the instrument. Furthermore, the proposed pseudo-kinematic model is extended to compensate for the coupled-hysteresis effect in a multi-DOF motion. A dynamic transmission model is also suggested that describes system’s response to high frequency inputs. Finally, the proposed motion transmission model was used for modeling of the backlash-like hysteresis in RAVEN II surgical robot

Modelling, Test and Practice of Steel Structures

This reprint provides an international forum for the presentation and discussion of the latest developments in structural-steel research and its applications. The topics of this reprint include the modelling, testing and practice of steel structures and steel-based composite structures. A total of 17 high-quality, original papers dealing with all aspects of steel-structures research, including modelling, testing, and construction research on material properties, components, assemblages, connection, and structural behaviors, are included for publication

Results of flutter test OS7 obtained using the 0.14-scale space shuttle orbiter fin/rudder model number 55-0 in the NASA LaRC 16-foot transonic dynamics wind tunnel

A 0.14-scale dynamically scaled model of the space shuttle orbiter vertical tail was tested in a 16-foot transonic dynamic wind tunnel to determine flutter, buffet, and rudder buzz boundaries. Mach numbers between .5 and 1.11 were investigated. Rockwell shuttle model 55-0 was used for this investigation. A description of the test procedure, hardware, and results of this test is presented