Next Issue
Previous Issue

Table of Contents

Robotics, Volume 7, Issue 2 (June 2018)

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
View options order results:
result details:
Displaying articles 1-17
Export citation of selected articles as:
Open AccessArticle A Simple Robotic Eye-In-Hand Camera Positioning and Alignment Control Method Based on Parallelogram Features
Received: 16 April 2018 / Revised: 8 June 2018 / Accepted: 15 June 2018 / Published: 18 June 2018
PDF Full-text (2973 KB) | HTML Full-text | XML Full-text
Abstract
A simple and effective method for camera positioning and alignment control for robotic pick-and-place tasks is described here. A parallelogram feature is encoded into each 3D object or target location. To determine the pose of each part and guide the robot precisely, a
[...] Read more.
A simple and effective method for camera positioning and alignment control for robotic pick-and-place tasks is described here. A parallelogram feature is encoded into each 3D object or target location. To determine the pose of each part and guide the robot precisely, a camera is mounted on the robot end-flange to determine and measure the location and pose of the part. The robot then adjusts the camera to align it with the located part so that it can be grasped. The overall robot control system follows a continuous look-and-move control strategy. After a position-based coarse alignment, a sequence of image-based fine alignment steps is carried out, and the part is then picked and placed by the robot arm gripper. Experimental results showed an excellent applicability of the proposed approach for pick-and-place tasks, and the overall errors were 1.2 mm for positioning and 1.0° for orientation angle. Full article
Figures

Figure 1

Open AccessArticle Optimal Kinematic Design of a 6-UCU Kind Gough-Stewart Platform with a Guaranteed Given Accuracy
Received: 24 April 2018 / Revised: 11 June 2018 / Accepted: 15 June 2018 / Published: 18 June 2018
PDF Full-text (1569 KB) | HTML Full-text | XML Full-text
Abstract
The 6-UCU (U-universal joint; C-cylinder joint) kind Gough-Stewart platform is extensively employed in motion simulators due to its high accuracy, large payload, and high-speed capability. However, because of the manufacturing and assembling errors, the real geometry may be different from the nominal one.
[...] Read more.
The 6-UCU (U-universal joint; C-cylinder joint) kind Gough-Stewart platform is extensively employed in motion simulators due to its high accuracy, large payload, and high-speed capability. However, because of the manufacturing and assembling errors, the real geometry may be different from the nominal one. In the design process of the high-accuracy Gough-Stewart platform, one needs to consider these errors. The purpose of this paper is to propose an optimal design method for the 6-UCU kind Gough-Stewart platform with a guaranteed given accuracy. Accuracy analysis of the 6-UCU kind Gough-Stewart platform is presented by considering the limb length errors and joint position errors. An optimal design method is proposed by using a multi-objective evolutionary algorithm, the non-dominated sorting genetic algorithm II (NSGA-II). A set of Pareto-optimal parameters was found by applying the proposed optimal design method. An engineering design case was studied to verify the effectiveness of the proposed method. Full article
(This article belongs to the Special Issue Kinematics and Robot Design)
Figures

Figure 1

Open AccessArticle Kinematics of the 3(RPSP)-S Fully Spherical Parallel Manipulator by Means of Screw Theory
Received: 16 May 2018 / Revised: 8 June 2018 / Accepted: 11 June 2018 / Published: 15 June 2018
PDF Full-text (696 KB) | HTML Full-text | XML Full-text
Abstract
In this work, the kinematics of a spherical parallel manipulator composed of three peripheral limbs equipped with linear actuators and a passive center shaft is approached by means of the theory of screws. The displacement analysis is carried out solving closure equations, which
[...] Read more.
In this work, the kinematics of a spherical parallel manipulator composed of three peripheral limbs equipped with linear actuators and a passive center shaft is approached by means of the theory of screws. The displacement analysis is carried out solving closure equations, which are obtained upon simple linear combinations of the components of two unit vectors describing the orientation of the moving platform. After, the input-output equations of velocity and acceleration of the spherical parallel manipulator are systematically obtained by resorting to reciprocal-screw theory. This strategy avoids the computation of the passive joint velocity and acceleration rates of the robot manipulator. Numerical examples illustrate the efficiency of the proposed method. Full article
(This article belongs to the Special Issue Feature Papers)
Figures

Figure 1

Open AccessArticle Lower Limb Exoskeleton for Rehabilitation with Improved Postural Equilibrium
Received: 28 March 2018 / Revised: 29 May 2018 / Accepted: 4 June 2018 / Published: 8 June 2018
PDF Full-text (882 KB) | HTML Full-text | XML Full-text
Abstract
In this work we present a lower limb haptic exoskeleton suitable for patient rehabilitation, specifically in the presence of illness on postural equilibrium. Exoskeletons have been mostly conceived to increase strength, while in this work patient compliance with postural equilibrium enhancement is embedded.
[...] Read more.
In this work we present a lower limb haptic exoskeleton suitable for patient rehabilitation, specifically in the presence of illness on postural equilibrium. Exoskeletons have been mostly conceived to increase strength, while in this work patient compliance with postural equilibrium enhancement is embedded. This is achieved with two hierarchical feedback loops. The internal one, closing the loop on the joint space of the exoskeleton offers compliance to the patient in the neighborhood of a reference posture. It exploits mechanical admittance control in a position loop, measuring the patient’s Electro Miographical (EMG) signals. The problem is solved using multi variable robust control theory with a two degrees of freedom setting. A second control loop is superimposed on the first one, operating on the Cartesian space so as to guarantee postural equilibrium. It controls the patient’s Center of Gravity (COG) and Zero Moment Point (ZMP) by moving the internal loop reference. Special attention has been devoted to the mechanical multi-chain model of the exoskeleton which exploits Kane’s method using the Autolev symbolic computational environment. The aspects covered are: the switching system between single and double stance, the system’s non-holonomic nature, dependent and independent joint angles, redundancy in the torque controls and balancing weight in double stance. Physical experiments to validate the compliance method based on admittance control have been performed on an elbow joint at first. Then, to further validate the haptic interaction with the patient in a realistic situation, experiments have been conducted on a first exoskeleton prototype, while the overall system has been simulated in a realistic case study. Full article
Figures

Figure 1

Open AccessArticle Hexapods with Plane-Symmetric Self-Motions
Received: 30 April 2018 / Revised: 5 June 2018 / Accepted: 5 June 2018 / Published: 8 June 2018
PDF Full-text (4742 KB) | HTML Full-text | XML Full-text
Abstract
A hexapod is a parallel manipulator where the platform is linked with the base by six legs, which are anchored via spherical joints. In general, such a mechanical device is rigid for fixed leg lengths, but, under particular conditions, it can perform a
[...] Read more.
A hexapod is a parallel manipulator where the platform is linked with the base by six legs, which are anchored via spherical joints. In general, such a mechanical device is rigid for fixed leg lengths, but, under particular conditions, it can perform a so-called self-motion. In this paper, we determine all hexapods possessing self-motions of a special type. The motions under consideration are so-called plane-symmetric ones, which are the straight forward spatial counterpart of planar/spherical symmetric rollings. The full classification of hexapods with plane-symmetric self-motions is achieved by formulating the problem in terms of algebraic geometry by means of Study parameters. It turns out that besides the planar/spherical symmetric rollings with circular paths and two trivial cases (butterfly self-motion and two-dimensional spherical self-motion), only one further solution exists, which is the so-called Duporcq hexapod. This manipulator, which is studied in detail in the last part of the paper, may be of interest for the design of deployable structures due to its kinematotropic behavior and total flat branching singularities. Full article
(This article belongs to the Special Issue Kinematics and Robot Design)
Figures

Figure 1

Open AccessArticle VETO: An Immersive Virtual Environment for Tele-Operation
Received: 12 April 2018 / Revised: 24 May 2018 / Accepted: 4 June 2018 / Published: 8 June 2018
PDF Full-text (11503 KB) | HTML Full-text | XML Full-text
Abstract
This work investigates an over-arching question: how can an immersive virtual environment be connected with its intelligent physical counterpart to allow for a more efficient man-machine collaboration. To this end, an immersive user interface for the purpose of robot tele-operation is designed. A
[...] Read more.
This work investigates an over-arching question: how can an immersive virtual environment be connected with its intelligent physical counterpart to allow for a more efficient man-machine collaboration. To this end, an immersive user interface for the purpose of robot tele-operation is designed. A large amount of sensory data is utilized to build models of the world and its inhabitants in a way that is intuitive to the operator and accurately represents the robot’s real-world state and environment. The game client is capable of handling multiple users, much like a traditional multiplayer game, while visualizing multiple robotic agents operating within the real world. The proposed Virtual Environment for Tele-Operation (VETO) architecture is a tele-operation system that provides a feature-rich framework to implement robotic agents into an immersive end-user game interface. Game levels are generated dynamically on a Graphic Processing Unit or GPU-accelerated server based on real-world sensor data from the robotic agents. A set of user studies are conducted to validate the performance of the proposed architecture compared to traditional tele-robotic applications. The experimental results show significant improvements in both task completion time and task completion rate over traditional tools. Full article
Figures

Figure 1

Open AccessArticle Deep Learning Systems for Estimating Visual Attention in Robot-Assisted Therapy of Children with Autism and Intellectual Disability
Received: 1 May 2018 / Revised: 18 May 2018 / Accepted: 30 May 2018 / Published: 4 June 2018
PDF Full-text (1347 KB) | HTML Full-text | XML Full-text
Abstract
Recent studies suggest that some children with autism prefer robots as tutors for improving their social interaction and communication abilities which are impaired due to their disorder. Indeed, research has focused on developing a very promising form of intervention named Robot-Assisted Therapy. This
[...] Read more.
Recent studies suggest that some children with autism prefer robots as tutors for improving their social interaction and communication abilities which are impaired due to their disorder. Indeed, research has focused on developing a very promising form of intervention named Robot-Assisted Therapy. This area of intervention poses many challenges, including the necessary flexibility and adaptability to real unconstrained therapeutic settings, which are different from the constrained lab settings where most of the technology is typically tested. Among the most common impairments of children with autism and intellectual disability is social attention, which includes difficulties in establishing the correct visual focus of attention. This article presents an investigation on the use of novel deep learning neural network architectures for automatically estimating if the child is focusing their visual attention on the robot during a therapy session, which is an indicator of their engagement. To study the application, the authors gathered data from a clinical experiment in an unconstrained setting, which provided low-resolution videos recorded by the robot camera during the child–robot interaction. Two deep learning approaches are implemented in several variants and compared with a standard algorithm for face detection to verify the feasibility of estimating the status of the child directly from the robot sensors without relying on bulky external settings, which can distress the child with autism. One of the proposed approaches demonstrated a very high accuracy and it can be used for off-line continuous assessment during the therapy or for autonomously adapting the intervention in future robots with better computational capabilities. Full article
(This article belongs to the Special Issue Intelligent Systems in Robotics)
Figures

Figure 1

Open AccessArticle A Structural Optimisation Method for a Soft Pneumatic Actuator
Received: 12 April 2018 / Revised: 21 May 2018 / Accepted: 30 May 2018 / Published: 1 June 2018
PDF Full-text (5402 KB) | HTML Full-text | XML Full-text
Abstract
This study aims to investigate the effects of various design parameters on the actuation performance of a pneumatic network actuator (PNA), optimise its structure using the finite element method (FEM), and subsequently quantify the performance of the resulting actuator topology experimentally. The effects
[...] Read more.
This study aims to investigate the effects of various design parameters on the actuation performance of a pneumatic network actuator (PNA), optimise its structure using the finite element method (FEM), and subsequently quantify the performance of the resulting actuator topology experimentally. The effects of the structural parameters, including the operation pressure, the wall thickness and the gap between the chambers, bottom layer thickness, and the geometry of the channel cross section, on the deformation and bending angle of the actuator were evaluated to optimise the performance of the pneumatic actuator. A Global Analysis of Variance (ANOVA) was performed to investigate how the variables affect the mechanical output of the actuator and, thus, the significance of variables affecting the deformation (and bending angle) of the pneumatic actuator was identified. After the parameter optimisation, a pneumatic channel with a 4.5 mm bottom layer thickness, 1.5 mm wall thickness, and 1.5 mm gap between sequential chambers is recommended to perform optimised bending motion for the pneumatic network actuator. The optimised FE model results were verified experimentally. This design optimisation method based on the FEM and ANOVA analysis can be extended to the topology optimisation of other soft actuators. Full article
Figures

Figure 1

Open AccessArticle Simple Reflex Controller for Decentralized Motor Coordination Based on Resonant Oscillation
Received: 7 April 2018 / Revised: 20 May 2018 / Accepted: 24 May 2018 / Published: 28 May 2018
PDF Full-text (722 KB) | HTML Full-text | XML Full-text
Abstract
This article describes an extremely simple controller as a minimal example of decentralized motor coordination and gait generation. The control strategy is based on the stretch reflex in animals and requires no mutual communication or detailed body models. Despite such simplicity, each controller
[...] Read more.
This article describes an extremely simple controller as a minimal example of decentralized motor coordination and gait generation. The control strategy is based on the stretch reflex in animals and requires no mutual communication or detailed body models. Despite such simplicity, each controller can sync itself and generate various resonant oscillation by only physical interaction through whole body dynamics. To evaluate this controller, we conduct some simulations with a linear spring–mass–damper system and a nonlinear legged robot model with multiple controllers. The former shows an adaptability to change in vibration frequency and the body parameter. In the latter, first we show a limitation of the proposed method due to the nonlinearity, and an alternative method is proposed. Finally, the simple controllers generate versatile gaits just by choosing a control parameter of “speeding up or down,” and the gait generation can be explained by the controllers–body integration based on resonant oscillation. Full article
Figures

Graphical abstract

Open AccessArticle Combining Hector SLAM and Artificial Potential Field for Autonomous Navigation Inside a Greenhouse
Received: 23 March 2018 / Revised: 17 May 2018 / Accepted: 19 May 2018 / Published: 22 May 2018
PDF Full-text (20789 KB) | HTML Full-text | XML Full-text
Abstract
The key factor for autonomous navigation is efficient perception of the surroundings, while being able to move safely from an initial to a final point. We deal in this paper with a wheeled mobile robot working in a GPS-denied environment typical for a
[...] Read more.
The key factor for autonomous navigation is efficient perception of the surroundings, while being able to move safely from an initial to a final point. We deal in this paper with a wheeled mobile robot working in a GPS-denied environment typical for a greenhouse. The Hector Simultaneous Localization and Mapping (SLAM) approach is used in order to estimate the robots’ pose using a LIght Detection And Ranging (LIDAR) sensor. Waypoint following and obstacle avoidance are ensured by means of a new artificial potential field (APF) controller presented in this paper. The combination of the Hector SLAM and the APF controller allows the mobile robot to perform periodic tasks that require autonomous navigation between predefined waypoints. It also provides the mobile robot with a robustness to changing conditions that may occur inside the greenhouse, caused by the dynamic of plant development through the season. In this study, we show that the robot is safe to operate autonomously with a human presence, and that in contrast to classical odometry methods, no calibration is needed for repositioning the robot over repetitive runs. We include here both hardware and software descriptions, as well as simulation and experimental results. Full article
(This article belongs to the Special Issue Agricultural and Field Robotics)
Figures

Figure 1

Open AccessArticle Analysis of Sheepdog-Type Robot Navigation for Goal-Lost-Situation
Received: 16 April 2018 / Revised: 10 May 2018 / Accepted: 17 May 2018 / Published: 18 May 2018
PDF Full-text (2177 KB) | HTML Full-text | XML Full-text
Abstract
In the real world, there is a system in which a dog called a sheepdog stimulates part of a flock of sheep that are freely moving to guide them to a goal position. If we consider this system from the perspective of a
[...] Read more.
In the real world, there is a system in which a dog called a sheepdog stimulates part of a flock of sheep that are freely moving to guide them to a goal position. If we consider this system from the perspective of a control problem, it is an interesting control system: one or more sheepdogs, who act as a small number of controllers, are used to indirectly control many sheep that cannot be directly controlled. For this reason, there have been many studies conducted regarding this system; however, these studies have been limited to building numerical models or performing simulation analyses. Very little research has been done on building a working system. The point we wish to emphasise here is that we attempted to build the sheepdog system in as simple a way as possible. For the purpose, we introduce minimal settings for the sheep model and the sheepdog controller. In the process of building and testing an actual system, we noticed “an emergence of blind zone” because the robots possess size, or so-called cases where the objects in the blind zone cannot be observed because the object is in front. Using the existing method, as the number of sheep increases, it becomes impossible to perceive the goal position, i.e., emerge the goal-lost-situation. This results in the guidance task becoming impossible. As clear identification of the goal position is vital for guidance, we propose a method for cases in which the goal position is invisible. Using our method, the robot appropriately selects another object, and sets this object as the new target. We have confirmed through simulations that the proposed method can maintain guidance regardless of the number of sheep. Full article
Figures

Figure 1

Open AccessArticle Motion Planning for a Chain of Mobile Robots Using A* and Potential Field
Received: 3 April 2018 / Revised: 15 May 2018 / Accepted: 15 May 2018 / Published: 18 May 2018
PDF Full-text (2294 KB) | HTML Full-text | XML Full-text
Abstract
Traditionally, motion planning involved navigating one robot from source to goal for accomplishing a task. Now, tasks mostly require movement of a team of robots to the goal site, requiring a chain of robots to reach the desired goal. While numerous efforts are
[...] Read more.
Traditionally, motion planning involved navigating one robot from source to goal for accomplishing a task. Now, tasks mostly require movement of a team of robots to the goal site, requiring a chain of robots to reach the desired goal. While numerous efforts are made in the literature for solving the problems of motion planning of a single robot and collective robot navigation in isolation, this paper fuses the two paradigms to let a chain of robot navigate. Further, this paper uses SLAM to first make a static map using a high-end robot, over which the physical low-sensing robots run. Deliberative Planning uses A* algorithm to plan the path. Reactive planning uses the Potential Field Approach to avoid obstacles and stay as close to the initial path planned as possible. These two algorithms are then merged to provide an algorithm that allows the robot to reach its goal via the shortest path possible while avoiding obstacles. The algorithm is further extended to multiple robots so that one robot is followed by the next robot and so on, thus forming a chain. In order to maintain the robots in a chain form, the Elastic Strip model is used. The algorithm proposed successfully executes the above stated when tested on Amigobot robots in an office environment using a map made by the Pioneer LX robot. The proposed algorithm works well for moving a group of robots in a chain in a mapped environment. Full article
(This article belongs to the Special Issue Intelligent Systems in Robotics)
Figures

Figure 1

Open AccessArticle Design, Kinematics and Controlling a Novel Soft Robot Arm with Parallel Motion
Received: 19 March 2018 / Revised: 10 May 2018 / Accepted: 16 May 2018 / Published: 17 May 2018
PDF Full-text (5477 KB) | HTML Full-text | XML Full-text
Abstract
This article presents a novel design for a double bend pneumatic muscle actuator (DB-PMA) inspired by snake lateral undulation. The presented actuator has the ability to bend in opposite directions from its two halves. This behavior results in horizontal and vertical movements of
[...] Read more.
This article presents a novel design for a double bend pneumatic muscle actuator (DB-PMA) inspired by snake lateral undulation. The presented actuator has the ability to bend in opposite directions from its two halves. This behavior results in horizontal and vertical movements of the actuator distal ends. The kinematics for the proposed actuator are illustrated and experiments conducted to validate its unique features. Furthermore, a continuum robot arm with the ability to move in parallel (horizontal displacement) is designed with a single DB-PMA and a two-finger soft gripper. The performance of the soft robot arm presented is explained, then another design of the horizontal motion continuum robot arm is proposed, using two self-bending contraction actuators (SBCA) in series to overcome the payload effects on the upper half of the soft arm. Full article
(This article belongs to the Special Issue Soft Machines: Integrating Sensing, Actuation and Computation)
Figures

Graphical abstract

Open AccessArticle Motion Investigation of a Snake Robot with Different Scale Geometry and Coefficient of Friction
Received: 1 March 2018 / Revised: 11 April 2018 / Accepted: 19 April 2018 / Published: 28 April 2018
PDF Full-text (1552 KB) | HTML Full-text | XML Full-text
Abstract
Most snakes in nature have scales at their ventral sides. The anisotropic frictional coefficient of the ventral side of the snakes, as well as snake robots, is considered to be responsible for their serpentine kind of locomotion. However, little work has been done
[...] Read more.
Most snakes in nature have scales at their ventral sides. The anisotropic frictional coefficient of the ventral side of the snakes, as well as snake robots, is considered to be responsible for their serpentine kind of locomotion. However, little work has been done on snake scales so far to make any guidelines for designing snake robots. This paper presents an experimental investigation on the effects of artificial scale geometry on the motion of snake robots that move in a serpentine manner. The motion of a snake robot equipped with artificial scales with different geometries was recorded using a Kinect camera under different speeds of the actuating motors attached to the links of the robot. The results of the investigation showed that the portion of the scales along the central line of the robot did not contributed to the locomotion of the robot, rather, it is the parts of the scales along the lateral edges of the robot that contributed to the motion. It was also found that the lower frictional ratio at low slithering speeds made the snake robot motion unpredictable. The scales with ridges along the direction of the snake body gave better and more stable motion. However, to get the peg effect, the scales needed to have a very high lateral to forward friction ratio, otherwise, significant side slipping occurred, resulting in unpredictable motion. Full article
(This article belongs to the Special Issue Kinematics and Robot Design)
Figures

Figure 1

Open AccessReview Robot Learning from Demonstration in Robotic Assembly: A Survey
Received: 11 February 2018 / Revised: 6 April 2018 / Accepted: 12 April 2018 / Published: 16 April 2018
PDF Full-text (5236 KB) | HTML Full-text | XML Full-text
Abstract
Learning from demonstration (LfD) has been used to help robots to implement manipulation tasks autonomously, in particular, to learn manipulation behaviors from observing the motion executed by human demonstrators. This paper reviews recent research and development in the field of LfD. The main
[...] Read more.
Learning from demonstration (LfD) has been used to help robots to implement manipulation tasks autonomously, in particular, to learn manipulation behaviors from observing the motion executed by human demonstrators. This paper reviews recent research and development in the field of LfD. The main focus is placed on how to demonstrate the example behaviors to the robot in assembly operations, and how to extract the manipulation features for robot learning and generating imitative behaviors. Diverse metrics are analyzed to evaluate the performance of robot imitation learning. Specifically, the application of LfD in robotic assembly is a focal point in this paper. Full article
(This article belongs to the Special Issue Feature Papers)
Figures

Figure 1

Open AccessArticle Prediction Governors for Input-Affine Nonlinear Systems and Application to Automatic Driving Control
Received: 26 February 2018 / Revised: 29 March 2018 / Accepted: 3 April 2018 / Published: 4 April 2018
PDF Full-text (657 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, automatic driving control has attracted attention. To achieve a satisfactory driving control performance, the prediction accuracy of the traveling route is important. If a highly accurate prediction method can be used, an accurate traveling route can be obtained. Despite the
[...] Read more.
In recent years, automatic driving control has attracted attention. To achieve a satisfactory driving control performance, the prediction accuracy of the traveling route is important. If a highly accurate prediction method can be used, an accurate traveling route can be obtained. Despite the considerable efforts that have been invested in improving prediction methods, prediction errors do occur in general. Thus, a method to minimize the influence of prediction errors on automatic driving control systems is required. This need motivated us to focus on the design of a mechanism for shaping prediction signals, which is called a prediction governor. In this study, we first extended our previous study to the input-affine nonlinear system case. Then, we analytically derived a solution to an optimal design problem of prediction governors. Finally, we applied the solution to an automatic driving control system, and demonstrated its usefulness through a numerical example and an experiment using a radio controlled car. Full article
Figures

Figure 1

Open AccessArticle Cable Robot Performance Evaluation by Wrench Exertion Capability
Received: 22 February 2018 / Revised: 23 March 2018 / Accepted: 25 March 2018 / Published: 27 March 2018
PDF Full-text (7219 KB) | HTML Full-text | XML Full-text
Abstract
Although cable driven robots are a type of parallel manipulators, the evaluation of their performances cannot be carried out using the performance indices already developed for parallel robots with rigid links. This is an obvious consequence of the peculiar features of flexible cables—a
[...] Read more.
Although cable driven robots are a type of parallel manipulators, the evaluation of their performances cannot be carried out using the performance indices already developed for parallel robots with rigid links. This is an obvious consequence of the peculiar features of flexible cables—a cable can only exert a tensile and limited force in the direction of the cable itself. A comprehensive performance evaluation can certainly be attained by computing the maximum force (or torque) that can be exerted by the cables on the moving platform along a specific (or any) direction within the whole workspace. This is the idea behind the index—called the Wrench Exertion Capability (WEC)—which can be employed to evaluate the performance of any cable robot topology and is characterized by an efficient and simple formulation based on linear programming. By significantly improving a preliminary computation method for the WEC, this paper proposes an ultimate formulation suitable for any cable robot topology. Several numerical investigations on planar and spatial cable robots are presented to give evidence of the WEC usefulness, comparisons with popular performance indices are also provided. Full article
(This article belongs to the Special Issue Kinematics and Robot Design)
Figures

Figure 1

Back to Top