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A giraffe using its tongue to extend its reach. A combination found in nature of a continuum manipulator at the end of rigid-linked structure. http://www.funnyanimalsite.com/pictures/Giraffe_Tongue.htm.
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In this paper, we examine key issues underlying the design and operation of robots featuring continuous body ("continuum") elements. We contrast continuum and continuum-like robots created to date with their counterparts in the natural world. It is observed that natural continuum locomotors or manipulators almost invariably rely on hard or discrete...
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We demonstrate manipulation of objects using the dynamics of a rope-like structure attached to a mobile robot as a passive tail. Three challenges arise in modeling and planning: the physics involved is nontrivial, the tail is underactuated, and motions of the object are nondeterministic. For such systems, some actions are well characterized by a si...
Citations
... Another current research field in which SMA actuators are gaining relevance is continuum robotics. Inspired by elephant trunks, tentacles, or snakes in nature, robotic structures are being developed without discrete mechanical joints [48,49]. SMA wires are suitable as manipulators for robotic structures, for example, in the medical field in endoscopes, guide wires or catheters. ...
Shape memory alloys (SMAs) have been established in a wide range of applications. Lead by the medical sector, nickel-titanium-based alloys are used for the realization of stents, guide wires, and other medical or surgical equipment. Besides this field, where mainly the superelastic material characteristics are used, first products based on actuation via the shape memory effect have been introduced to the market. These shape memory actuators or actuator systems either use temperature change directly for the realization of work output, for example, in thermostat valves, or are thermally activated by an applied electric current. This chapter gives an overview of recent SMA-based actuator systems and applications in a variety of fields from industry over bionics to automotive and aerospace.
... More details and information is necessary. However, more control effort is usually needed to maintain the position accuracy and repeatability of CRs (Cowan and Walker, 2013). ...
Traditional aerial manipulation systems were usually composed of rigid-link manipulators attached to an aerial platform, arising several rigidity-related issues such as difficulties of reach, compliant motion, adaptability to object’s shape and pose uncertainties, and safety of human-manipulator interactions, especially in unstructured and confined environments. To address these issues, partially compliant manipulators, composed of rigid links and compliant/flexible joints, were proposed; however, they still suffer from insufficient dexterity and maneuverability. In this article, a new set of compliant aerial manipulators is suggested. For this purpose, the concept of aerial continuum manipulation system (ACMS) is introduced, several conceptual configurations are proposed, and the functionalities of ACMSs for different applications are discussed. Then, the performances of proposed aerial manipulators are compared with conventional aerial manipulators by implementing available benchmarks in the literature. To enhance the comparison, new features with related benchmarks are presented and used for evaluation purposes. In this study, the advantages of ACMSs over their rigid-link counterparts are illustrated and the potential applications of ACMSs are suggested. The open problems such as those related to dynamic coupling and control of ACMSs are also highlighted.
... The design of robotic arms has been part of the robotics evolution by incorporating not only new materials and mechanical structures, but also novel application-specific models. An example of this evolution is hyper-redundant robots; these have a mechanical structure capable of deforming continuously according to their degrees of freedom (DoF) to adapt to disorderly (unstructured) environments [10,11]; these robots resemble living organisms or their parts, such as snakes or elephant trunks; they are denoted as continuous manipulators and are widely applied in the medical area (for minimal invasive surgeries), for in-orbit servicing, grasping, and locomotion in unstructured environments [5,12,13]. However, working with this type of robot implies solving complex and computationally costly inverse kinematics and real-time collision-free path planning problems [10,11,14]. ...
... An example of this evolution is hyper-redundant robots; these have a mechanical structure capable of deforming continuously according to their degrees of freedom (DoF) to adapt to disorderly (unstructured) environments [10,11]; these robots resemble living organisms or their parts, such as snakes or elephant trunks; they are denoted as continuous manipulators and are widely applied in the medical area (for minimal invasive surgeries), for in-orbit servicing, grasping, and locomotion in unstructured environments [5,12,13]. However, working with this type of robot implies solving complex and computationally costly inverse kinematics and real-time collision-free path planning problems [10,11,14]. ...
... The EHPPM can model the obstacles by two separate sets, namely a set of circles (circular obstacles) and another set of ellipsoidal approximations (ellipsoidal obstacles) [22][23][24]. As a result, W(x, y) can be represented by Equation (11). ...
Achieving the smart motion of any autonomous or semi-autonomous robot requires an efficient algorithm to determine a feasible collision-free path. In this paper, a novel collision-free path homotopy-based path-planning algorithm applied to planar robotic arms is presented. The algorithm utilizes homotopy continuation methods (HCMs) to solve the non-linear algebraic equations system (NAES) that models the robot’s workspace. The method was validated with three case studies with robotic arms in different configurations. For the first case, a robot arm with three links must enter a narrow corridor with two obstacles. For the second case, a six-link robot arm with a gripper is required to take an object inside a narrow corridor with two obstacles. For the third case, a twenty-link arm must take an object inside a maze-like environment. These case studies validated, by simulation, the versatility and capacity of the proposed path-planning algorithm. The results show that the CPU time is dozens of milliseconds with a memory consumption less than 4.5 kB for the first two cases. For the third case, the CPU time is around 2.7 s and the memory consumption around 18 kB. Finally, the method’s performance was further validated using the industrial robot arm CRS CataLyst-5 by Thermo Electron. View Full-Text
... Comparing with the rigid articulated robot arm, the continuum robot offers preferable compliance by diminishing the stiffness, but also certainly leads to decreasing the stability and the accuracy [15], especially when the scale of the continuum robot is larger [16,17]. Moreover, the payload and the gravity considerably further reduce the precision of motion planning, and increase the challenge in controlling a continuum robot due to its insufficient stiffness [18]. ...
This paper presents a novel robot arm that is capable of switching between a rigid robot arm and a continuum robot arm. Therefore, the novel robot arm can perform adaptive physical interaction and manipulation against complex working environments and tasks. The switch-ability of the robot arm is achieved with two types of joints: knee-like flexible joints and continuum flexible joints, with which the continuum segment of the robot arm is capable of locking and losing, hence the degree of freedom of the robot arm is capable to be switched. In this work, kinematics is established for specifying the relationship between joints space and global coordinates in both rigid and continuum configurations. Then, the posture and workspace in rigid and continuum configurations are analyzed and illustrated with numerical simulations, and compared based on the established kinematic model. Finally, a series of preliminary experimental testing toward the joint motion and stiffness has been carried out to validate the design, the kinematic model, and the motion performance of the proposed robot arm. Both the numerical and experimental results show that the knee-like joints can guarantee favorable motion accuracy, and the motion of continuum segment from the testing is well aligned with the motion calculated from the theoretical model. Moreover, the stiffness of rigid configuration is larger than the continuum configuration based on the stiffness experiment results. Therefore, the proposed novel robot arm is capable to handle adaptive interaction and manipulation in a diverse environment through the switching between the rigid and continuum configurations.
... More importantly, continuum robots can interact safely with humans [ 3 , 4 , 11 ]. Inspired by biology in nature, many kinds of continuum robots are proposed, such as octopus-inspired robots [12] , tendril continuum manipulators [13] , snake-like robots [14] , Nomenclature ξ Normalized arc-length parameter. · Derivative with respect to time. ...
The accurate dynamic model for continuum robots is necessary to expand their range of applications. In this paper, a modular approach is proposed for dynamic modeling of cable-driven multisegment continuum robots. The previous dynamic models are usually formulated as a set of ordinary differential equations. However, the derived dynamic model in this paper is formulated as a set of differential-algebraic equations, resulting in the coefficient matrices of adjacent modules being decoupled. Reformulation of the existing coefficient matrices is not required as the number of modules increases, which makes the presented approach suitable for modular modeling. The continuum deformations, including elongation or contraction, bending, and torsion, are taken into account. Hermite interpolation is adopted to describe the flexible shape of each backbone, avoiding the singularity and additional constraints of constant strains. Static and dynamic experiments were implemented on continuum robot prototypes. The normalized errors are less than 3.83% and 6.93% of the robot length in the static and dynamic experiments. The presented model is experimentally validated.
... The design of discrete and continuum manipulators was inspired by nature. Many organisms like monkeys, Climbing morning glory vine, Octopus, Stingray, Komodo dragon, giraffe, brittle star, basket star use the same mechanism as that of discrete and continuum manipulators for their survival [5]. The use of flexible discrete manipulators in cobots increases its efficiency in terms of production and safety. ...
Proposed two-link flexible manipulators suit the requirement of larger work volume than the traditional flexible manipulators and handle high payloads equal to that of rigid manipulators. The simulation was performed on the Computer-Aided Design (CAD) model of the Motoman HC-10DT, a Human-Collaborative robot. During the analysis, one link of the manipulator was modified as a flexible manipulator for which static and modal analysis was done and compared the results with the actual link of the robot to validate the proposed design. The kinematic analysis was also done to find the reach of the modified robot. Total deformation on both the flexible manipulator and the actual link of the robot was 0.2mm but the maximum von Mises stress acting on the flexible manipulator was 2.97% lesser than that of the rigid link of the robot. Eventually, the safety factor of the flexible manipulator was higher compared to the rigid link. The factor of safety of the upper link is 1.41 and the lower link is 1.51 whereas the actual link of the robot has the safety factor of 1.30.
... Moreover, in the space industry robots play an important role in imaging and investigating the characteristics of components in space research [8]. The heavy use of robots in industrial applications results from their stable quality and productivity level, cost minimization, and safety improvements in dangerous environments [9]. The selection of robots for a particular application and manufacturing environment is a difficult task for decision makers. ...
The gap between researchers who carry out scientific exploration and practitioners who can make use of the research results is well known. In addition, while practitioners place a high value on research, they do not read many research papers. This paper attempts to define and prioritise future research in robotics using the analytical hierarchy process (AHP). Fifteen research alternatives and gaps, five performance criteria, eight industry types, and six production processes, investigated by both academics and practitioners, are filtered to six alternatives, four performance criteria, three industry types, and three production processes, respectively, based on the most important factors in decision-making. Subsequently, they are analysed by the Expert Choice software. This research aims at bridging the gap between academics and practitioners in robotics research and at conducting research that is relevant to industry. The results indicate that the research in multi-robot control ranked first with 26.8%, followed by the research in safe control with 23.3% and the research in remote robot supervision with 19.0%. The research in force control ranked fourth with 17.8%, followed by the research in 3D vision and wireless communication with 8.4% and 6.4%, respectively. Based on the results, the academics involved in robotics research should direct their effort to the research activities that received the highest priority in the AHP model.
... Moreover, in the space industry robots play an important role in imaging and investigating the characteristics of components in space research [8]. The heavy use of robots in industrial applications results from their stable quality and productivity level, cost minimization, and safety improvements in dangerous environments [9]. The selection of robots for a particular application and manufacturing environment is a difficult task for decision makers. ...
The gap between researchers who carry out scientific exploration and practitioners who can make use of the research results is well known. In addition, while practitioners place a high value on research, they do not read many research papers. This paper attempts to define and prioritise future research in robotics using the analytical hierarchy process (AHP). Fifteen research alternatives and gaps, five performance criteria, eight industry types, and six production processes, investigated by both academics and practitioners, are filtered to six alternatives, four performance criteria, three industry types, and three production processes, respectively, based on the most important factors in decision-making. Subsequently, they are analysed by the Expert Choice software. This research aims at bridging the gap between academics and practitioners in robotics research and at conducting research that is relevant to industry. The results indicate that the research in multi-robot control ranked first with 26.8%, followed by the research in safe control with 23.3% and the research in remote robot supervision with 19.0%. The research in force control ranked fourth with 17.8%, followed by the research in 3D vision and wireless communication with 8.4% and 6.4%, respectively. Based on the results, the academics involved in robotics research should direct their effort to the research activities that received the highest priority in the AHP model.
... Continuum robots have increased flexibility, and thereby dexterity, compared to their rigid-link counterparts (the importance of continuum robots [7]). Figure 1 from [8] illustrates the essential difference between a discrete, a serpentine, and a continuous-link structure. ...
This paper presents a literature survey documenting the evolution of continuum robots over the past two decades (1999–present). Attention is paid to bioinspired soft robots with respect to the following three design parameters: structure, materials, and actuation. Using this three-faced prism, we identify the uniqueness and novelty of robots that have hitherto not been publicly disclosed. The motivation for this study comes from the fact that continuum soft robots can make inroads in industrial manufacturing, and their adoption will be accelerated if their key advantages over counterparts with rigid links are clear. Four different taxonomies of continuum robots are included in this study, enabling researchers to quickly identify robots of relevance to their studies. The kinematics and dynamics of these robots are not covered, nor is their application in surgical manipulation.
... The ideas presented in this section complement previous treatments of cognitive time (VanRullen and Koch 2003) including the notion of a 'perceptual moment' (Allport 1968;Shallice 1964;Stroud 1967), and the suggestion that brain oscillations act as discrete clocks to support this type of computation (Buschman and Miller 2009;Buschman and Miller 2010b). They also resonate with recent developments in machine learning (Linderman et al. 2017) and some of the problems faced in modern robotics (Cowan and Walker 2013;Schaal 2006). In short, the coupling of categorical decision making and dynamic perception (and motor control) raises some deep questions about the temporal scheduling of perception (and action). ...
In this thesis, we appeal to recent developments in theoretical neurobiology – namely, active inference – to understand the active visual system and its disorders. Chapter 1 reviews the neurobiology of active vision. This introduces some of the key conceptual themes around attention and inference that recur through subsequent chapters. Chapter 2 provides a technical overview of active inference, and its interpretation in terms of message passing between populations of neurons. Chapter 3 applies the material in Chapter 2 to provide a computational characterisation of the oculomotor system. This deals with two key challenges in active vision: deciding where to look, and working out how to look there. The homology between this message passing and the brain networks solving these inference problems provide a basis for in silico lesion experiments, and an account of the aberrant neural computations that give rise to clinical oculomotor signs (including internuclear ophthalmoplegia). Chapter 4 picks up on the role of uncertainty resolution in deciding where to look, and examines the role of beliefs about the quality (or precision) of data in perceptual inference. We illustrate how abnormal prior beliefs influence inferences about uncertainty and give rise to neuromodulatory changes and visual hallucinatory phenomena (of the sort associated with synucleinopathies). We then demonstrate how synthetic pharmacological perturbations that alter these neuromodulatory systems give rise to the oculomotor changes associated with drugs acting upon these systems. Chapter 5 develops a model of visual neglect, using an oculomotor version of a line cancellation task. We then test a prediction of this model using magnetoencephalography and dynamic causal modelling. Chapter 6 concludes by situating the work in this thesis in the context of computational neurology. This illustrates how the variational principles used here to characterise the active visual system may be generalised to other sensorimotor systems and their disorders.
