Rafael Aracil

Motion planning of a climbing parallel robot

Proposes an application of the Stewart-Gough parallel platform as a climbing robot and its kinematics control to climb through long structures describing unknown spatial trajectories, such as palm trunks, tubes, etc. First, the description and design of the climbing parallel robot is presented. Second, the inverse and forward kinematics analysis of a mobile six-degrees-of-freedom parallel robot is described, based on spatial constraint formulation. Finally, the gait pattern and the climbing strategy of the parallel robot is described. The information from this research is being used in an actual climbing parallel robot design at Miguel Hernandez University of Elche (Alicante), Spain.

Advances in Telerobotics

The main purpose of this book is to provide readers with recent advances in the field of Telerobotics. It describes methods, experimental results, applications, and developments, highly relevant for scientists, researchers, and students in Teleoperation. This book is structured in three parts: I. Human System Interfaces, II. Control, and III. Applications. Chapters in part I concentrate on human interface technology which allows a human operator to close the control loop of a remote robot. Topics related to control algorithms - in particular for the case with time delay in the communication network - are the focus in part II, concentrating on bilateral control methods. Part III presents a variety of advanced applications in surgery, space, and other fields relevant to everyday life. The book is complemented by a CD-ROM containing fifteen research videos, which make the contents of the book even more descriptive.

Parallel robots for autonomous climbing along tubular structures

Abstract This paper proposes the application of the Gough–Stewart (G–S) platform as a climbing robot. The idea of using the parallel G–S platform as a climbing robot is a novel solution to carry out tasks that imply a high risk for workers who have to climb on tubular structures. Some mechanical adaptations allow to convert the G–S platform in an autonomous and teleoperated robot capable to move autonomously along tubular structures (posts, steel wires of bridges, trunks of palms, pipes, etc.) or inside of fluid conducting pipes. To show the capacity of using this G–S platform as climbing robot we propose several mechanical designs capable of climbing through these tubular structures. Taking into account these designs and their functionality, we study the dynamics of some different configurations of these robots. In the second part of the paper we present a first prototype used as a climbing robot, developed to climb on palm trunks. Technical specifications of the system are presented and the control scheme is analyzed. Finally several experiments show the capability of this parallel robot to climb on tubular structures.

A climbing parallel robot: a robot to climb along tubular and metallic structures

This article presents the promising applications that can be obtained from parallel robots for climbing. It explores the most important aspects of the mechanical design and control of climbing parallel robots (CPRs) based on the Stewart-Goughs (S-G) platform for tasks in tubular or metallic structures.

Generalized control method by state convergence for teleoperation systems with time delay

In this paper a generalized design and control method for teleoperation systems with communication time delay is presented. The design method is based on the state space formulation and it allows to obtain the control parameters for any teleoperation system where the master and the slave manipulators would be represented by nth-order linear differential equations. Through state convergence between the master and the slave, the control system allows the slave to follow the master inspite of the time delay. The method is also able to establish the desired dynamics of this convergence and the dynamics of the slave manipulator. Experimental results are presented showing the validity of the proposed design and control method.

Telerobotic system for live-power line maintenance: ROBTET

Abstract This paper is focused on a telerobotic application for the maintenance of electrical live-power lines, called “ROBTET”. Maintenance-related tasks are of great relevance for utilities companies, as their goal of achieving a good service quality depends to a great extent on maintenance and inspection issues. On live lines up to 69 kV , the tasks are carried out by teleoperated robots. These manipulators are teleoperated by a human operator sitting in a vehicle required to place the telerobotic system over the desired line. In this paper, the main developments in live-line teleoperated systems are mentioned, followed by a detailed description of the ROBTET. This telerobotic system has been developed by the Universidad Politecnica de Madrid, in collaboration with Iberdrola and Cobra, a Spanish utility company and contractor, respectively. The ROBTET system has been in operation in the Spanish electricity network for over a year, which attests to the success of the prototype and also allows for the incorporation of improvements.

Robotized spraying of prefabricated panels

A robotic manufacturing cell of pre-fabricated glass reinforced cement panels for construction industry has been developed by DISAM for the Spanish construction company Dragados, SA. The main contribution of the developed system is the automatic programming and control of the whole plan. The architects 3D-drawing of the building facade done on a CAD system serves as input. From the CAD design, the optimum facade to panels partition is obtained. In order to manufacture each panel, automatic task and path planning are performed for the equipment present in the manufacturing cell: spraying robot, PLCs, control computer, etc.

Human hand descriptions and gesture recognition for object manipulation

This work focuses on obtaining realistic human hand models that are suitable for manipulation tasks. A 24 degrees of freedom (DoF) kinematic model of the human hand is defined. The model reasonably satisfies realism requirements in simulation and movement. To achieve realism, intra- and inter-finger constraints are obtained. The design of the hand model with 24 DoF is based upon a morphological, physiological and anatomical study of the human hand. The model is used to develop a gesture recognition procedure that uses principal components analysis (PCA) and discriminant functions. Two simplified hand descriptions (nine and six DoF) have been developed in accordance with the constraints obtained previously. The accuracy of the simplified models is almost 5% for the nine DoF hand description and 10% for the six DoF hand description. Finally, some criteria are defined by which to select the hand description best suited to the features of the manipulation task.

Design, modelling and implementation of a 6 URS parallel haptic device

Abstract Tactile exploration of remote or virtual environments needs a mechanical interface that allows the operator to interact with the remote zone. Parallel platforms offer advantages that make them suitable for working as master devices in a bilateral teleoperation scheme. This paper proposes the modification of a 6 UPS Gough–Steward platform by interchanging the linear actuators by cable-driven pantographs with rotational electric actuators in order to improve the workspace and output bandwidth. The paper presents the mechanical design, the geometric and dynamic model, and control algorithms of a 6 URS platform developed to be used either as an impedance display that reads the position of the operator and reflects force or as an admittance display that reads the Cartesian forces and reflects positions.

Climbing parallel robot: a computational and experimental study of its performance around structural nodes

This paper presents a study of the kinematics and dynamics performance of a climbing parallel robot (CPR) to avoid nodes on structural frames. To avoid a structural node, a CPR can acquire some determined postures. A series of postures can be combined to generate the convenient movements to climb along the structural node. The postures of a CPR must be studied to detect its feasibility, because the postures can drive the robot near its singular configurations. Also, the forces originated in the actuators to evade the structural nodes are evaluated. Therefore, the goal of this paper is to show that a Stewart-Gough (S-G) parallel platform can be used as a climbing robot, because a CPR can avoid structural nodes easily and elegantly, in contrast with other types of robots. To support the simulation results presented in the first part of this paper, an experimental testbed has been developed to study the dynamic performance of the CPR prototype around a structural node. The results obtained are very interesting, and show that an industrial potential to use the parallel S-G robot as a climbing robot exists.