Authors: Giorgio Cannata, Mirko D'Andrea, Marco Maggiali, Francesca Monti

Abstract: This paper presents a model for a tendon driven robot eye designed to emulate the actual saccadic and smooth pursuit movements performed by human eyes. Physiological saccadic motions obey the so called Listing's Law which constrains the admissible eye's angular velocities. The paper discusses conditions making possible to implement the Listing's Law on a purely mechanical basis, i.e. without active control.

Keywords: robot eye,Listing's law,tendon actuated robots

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Filoktimon Repoulias, Evangelos Papadopoulos

Abstract: This paper considers the problem of spatial planning and open-loop control for underactuated AUVs. Given a smooth inertial 3D trajectory to be followed by some vehicle point, the developed algorithm uses the vehicle dynamic model, and computes the 3D corresponding body-fixed linear and angular velocities as well as vehicle orientations, yielding a feasible 6 DOF trajectory. The design of tracking controllers is then facilitated by using this trajectory, which is consistent with AUV dynamics. The full 6 DOF computed trajectory is further used to compute the efforts for the three available control inputs and to result in an open-loop trajectory controller.

Keywords: underactuated AUV,3D trajectory planning,tracking

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Emanuel Slawinski, Jose Postigo, Vicente Mut, Carlos Soria

Abstract: This paper addresses a stable control structure for the bilateral teleoperation of mobile robots with visual feedback in presence of time-varying delay. The proposed control structure uses estimated parameters of the human operator and a fictitious force which is calculated using data fusion from ultrasonic sensors and optical flow field from panoramic images. To illustrate the performance and stability of the proposed control structure, several teleoperation experiments between Argentina and Brazil linked via Internet are shown.

Keywords: internet,mobile robots,teleoperation,time-varying delay

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Thomas Hulin, Carsten Preusche, Gerd Hirzinger

Abstract: This paper is about haptic simulations of virtual walls, which are represented by a discrete PD-control. A normalized discrete-time transfer function is used to derive the fundamental stability boundaries for this problem. Hereby, the case of direct action and the more often case of an one sampling step delayed action are addressed. Inside the stable region the set of all parameters was determined that result in real system poles. Furthermore, three different design criteria are compared to find optimum control parameters for the virtual wall. Finally, important conclusions for haptic simulations are derived.

Keywords: haptic rendering,virtual spring,virtual damper,PD-control,stability boundary,virtual wall

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Rezia Molfino, Roberto P. Razzoli, Matteo Zoppi

Abstract: The paper addresses the flexible assembly and disassembly of electro-mechanical products in white industry. The work is in the frame of a research project on modular assembly systems for innovative production systems. For the assembly and disassembly of washing-machine components, instead of a sequence of dedicated stations with specialized grippers designed for each component, the alternative solution of highdegree-of-freedom assembly cells using reconfigurable grippers for components holding and handling is investigated. A low-cost, multifunctional adaptable gripper for handling cylindrical and prismatic shaped parts within dimensional ranges typical of the washing machines components, as provided by the industrial partner Electrolux-Zanussi, is presented and its functionalities shown and evaluated.

Keywords: assembly,design,automation,handling,manipulation

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Jean Michel Pflimlin, Philippe Soueres, Tarek Hamel, Robert Mahony

Abstract: This paper describes a control strategy to stabilize the position of a Vertical Takeoff and Landing (VTOL) Unmanned Aerial Vehicle (UAV) in crosswind. The proposed approach takes advantage of the cascade structure of the system to design a hierarchical controller involving a High Level Controller devoted to position control and a Low Level Controller devoted to attitude stabilization. Both controllers are designed by means of backstepping techniques that allow the stabilization of the vehicle's position while on-line estimation of the unknown aerodynamic forces. Simulations as well as experimental results are presented to illustrate the concept.

Keywords: VTOL UAV,ducted fan,attitude control,position control

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: S. Torres, J. A. Mendez, L. Acosta, V. M. Becerra

Abstract: This work presents a new robust control scheme for articulated robotic systems. The aim of the controller is to add an adaptive scheme to the standard robust controller in order to improve its performance, especially in the case of unknown parameters or unknown variable loading. This paper presents real results for a Puma-560 robot, comparing the new strategy with the classical robust controller. They show a case in which the original controller does not exhibit a good performance, due to the presence of model uncertainties. The new strategy tries to tune automatically the uncertainty bound parameter of the robust action and results show that it has a satisfactory behaviour compared with the previous strategies.

Keywords: robust control,robot manipulators,adaptive control

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: L. F. Baptista, J. M. M. Martins, J. M. G. Sa da Costa

Abstract: One of the major drawbacks of flexible-link robot applications is its low tip precision, which is an essential characteristic for applications with position and interaction control with a contact surface. In this paper, position and interaction control strategies considering a rigid contact surface are applied to a flexible-link manipulator. The applied strategies are based on the closed-loop inverse kinematics algorithm (CLIK) to obtain the desired angular references to the joint position controller. The control schemes were previously tested by simulation and further implemented on a two degrees of mobility flexible-link planar robot. The obtained experimental results exhibit a good position and force tracking performance. The overall results reveal the successful implementation of the control architectures for a robot with one flexible link.

Keywords: flexible-link manipulator,closed loop inverse kinematics,tip position control,interaction control,real-time control

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Daniele Fontanelli, Riccardo Viviani, Luca Greco, Andrea Caiti, Antonio Bicchi

Abstract: Research of a modular stabilizing control law for uncertain, nonholonomic mobile systems with actuators limitation has been investigated. Modular design allows the definition of a stabilizing control law for the kinematic model. The presence of uncertainties in the actuators parameters or in the vehicle dynamics has been treated both adding suitable components to the Lyapunov function and using parameters adaptation laws (e.g. adaptive control and backstepping techniques). Simulations are reported for the set point stabilization of a unicycle like vehicle showing the feasibility of the proposed approach. Torque limitations for a unicycle like vehicle has been investigated using backstepping techniques for the vehicle tracking problem. Simulations are reported.

Keywords: nonholonomic systems,adaptive control,limited actuation,vehicle control

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: U. Spaelter, E. Samur, H. Bleuler

Abstract: Haptic Devices are key elements of surgery simulators, as they allow surgeons to experience the contact forces during the manipulation of the virtual tissue in a training session. Friction drives add important features to surgery simulation, like tool insertion and complete removal during the training and thus add realism to the simulation. In this paper we present a 2-DOF friction drive for smooth and slip-free tool translation and rotation, which is part of a 4-DOF haptic device for training of a gynecologic intervention (hysteroscopy). We present a specially developed mechanical design and the control structure for efficient friction compensation and low force ripple in the context of high quality haptic (force feedback) systems. The prototype is presented and experimental results are discussed.

Keywords: haptic device,mechanical and control design,surgery simulation,friction drive

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Matthew Spenko, Steven Dubowsky, Karl Iagnemma

Abstract: At high speeds in natural terrain, unmanned ground vehicles can experience unexpected situations that require rapid hazard avoidance maneuvers. In these scenarios there is often limited time to replan a path based on high-order dynamic models. This paper presents a novel method for high speed navigation and hazard avoidance based on the two dimensional "trajectory space", a compact and computationally efficient model-based representation of a robot's dynamic performance limits on natural terrain. This paper also presents a novel method for trajectory replanning, based on a "curvature matching" technique. Experimental results on a small high-speed UGV demonstrate the method's effectiveness.

Keywords: autonomous mobile robots,obstacle avoidance

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: None

Abstract:

Keywords:

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Nabil Zemiti, Guillaume Morel, Barthelemy Cagneau, Delphine Bellot, Alain Micaelli

Abstract: In this paper, we consider the problem of force control for kinematically constrained manipulators (KCMs). In particular, we show that the force component selection is not appropriate in general to solve the force control problem for KCMs. Moreover, by formulating the problem in the joint space, we show how to properly design a stable force controller for KCMs subject to arbitrary external forces applied to their end-effector. Experimental results with a kinematically constrained laparoscopic comanipulator illustrate these propositions.

Keywords: force control,passivity,kinematic instability,surgical robotics

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: G. Pezzuto, J. Gancet, S. Nabulsi

Abstract: The paper explains the recent improvements in the control architecture of a four-legged, two-roped walking robot conceived and designed for consolidation of almost vertical and irregular rocky walls. Saferdrill robot, whose development is funded by EC under Co-operative Research programme, must operate in harsh conditions and remotely controlled in order to make positioning and performing downhill drilling up to 20 m from a remote and safe place. The system architecture used to coordinate the manoeuvrability of the positioning, the drilling process, and the remote operation of the machine are explained.

Keywords: control system design,industrial robot,robotics,remote control,users interfaces

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Francisco J. T. Vargas, Edson R. De Pieri, Eugenio B. Castelan, Cristiane C. Paim

Abstract: This paper presents an experimental implementation of position and force control of a like industrial manipulator considering robustness and friction compensation aspects. Project of controllers are done using the De Luca and Manes model and a control strategy based on Variable Structure Control (VSC). Practical implementation is done considering tasks as cut of material and tracking reference for force and position. These tasks were implemented in a research SCARA robot, with four degrees of freedom with force sensor and open architecture of control.

Keywords: friction compensation,position and force control,robustness

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Mahmoud Tarokh, Xiaomang Zhang

Abstract: The paper presents a genetic algorithm approach to real-time trajectory tracking of redundant and non-redundant manipulators. The joint angle trajectories are found by applying genetic operators to a set of suitably generated configurations so that the end-effector follows a desired workspace trajectory accurately. The probability of applying a particular genetic operator is adapted on-line to achieve fast convergence to the solution. The adaptation is based on two measures, namely, diversity and fitness of the generated configurations. In order to achieve fast tracking, special provisions are made so that only an appropriate small region in the joint space is searched. The tracking problem is solved at the position rather the then velocity level. As such the proposed method does not use the manipulator Jacobian inverse or pseudo-inverse matrix and is shown to be free from problems such as excessive joint velocities due to singularities. Simulation results are presented for the 6-DOF Puma and the 7-DOF Robotic that show good tracking accuracy and reasonable joint velocities.

Keywords: robot trajectory tracking,genetic algorithms

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Raul Suarez, Gerrit Farber

Abstract: Determining the grasp optimal configuration of a mechanical hand is a computational hard work, mainly due to the large number of degrees of freedom (fingers and wrist) and possible solutions, and to the constraints imposed by the object. The paper presents an approach to reduce this problem under certain conditions. The configurations of the hand to grasp rectangular parallelepipeds of different sizes are determined off-line using an optimality criterion. The wrist positions of these configurations are approximated with functions of the size of the object "inside" the hand. These functions are stored to be used for a fast on-line computation of a real grasp configuration. The approach has been implemented and numerical examples are presented.

Keywords: robot hands,grasping and manipulation

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Riccardo Morselli, Roberto Zanasi

Abstract: The port Hamiltonian framework is a powerful tool for modeling a wide class of nonlinear systems such as robots and, more generally, mechatronic systems. A wide variety of mechatronic systems are controlled by operating dissipative components and the standard approaches for the control of port Hamiltonian systems are not applicable. Facing the limitation that the controlled devices can only dissipate power, the issue is to find a proper control law to satisfy the control requirements. This paper proposes to choose the control inputs to lead the input power of a subsystem in oder to satisfy the requirements by controlling the energy stored or the power dissipated in that subsystem. A slight extension of the definition of port Hamiltonian system is proposed to allow the description of a larger set of mechatronic systems. Although some important issues remain open, the example of the semi-active suspension shows that some positive results can be achieved by applying the proposed approach.

Keywords: nonlinear control,automotive control,semi-active suspension

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Vinicius Menezes de Oliveira, Walter Fetter Lages

Abstract: This work is focused on the position control of an underactuated brachiation mobile robot with 3 links. We present the modeling of the dynamics of the robot and introduce the application of the nonlinear model-based predictive control (NMPC) to such a system. The robot has 3 revolute joints but only one of them is actuated, i.e., the robot has less control inputs than degrees of freedom. The investigation of the NMPC to control such a system is due to the fact that NMPC is able do deal with constraints (state or input limitations) in a direct way, obtaining an optimal control law. Simulation results are shown, as well as some directions for future developments.

Keywords: brachiation mobile robot,nonlinear control,underactuated systems,NMPC

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Fernando Zumbado, Marcia K. O'Malley

Abstract: This paper describes the time-domain identification of the three translational degrees-of-freedom of a six degree-of-freedom hand controller, used to teleoperate Robonaut, a humanoid robotic assistant developed by NASA. Each axis is independently identified due to the decoupled nature of the manipulator design. Results of the identification experiments are presented, including implications of assumptions of decoupling and linearity. Future work will include identification of the rotational degrees of freedom of the FRHC gimbal, development of a linear parameter varying model, and incorporation of this model into a simulation of the bilateral teleoperation system.

Keywords: system identification,robot dynamics,robotic manipulators,telemanipulation,frequency domain,human-machine interface

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Kristijan Macek, Roland Siegwart

Abstract: This paper addresses the problem of path planning of mobile robots in dynamic environments. A collision-free trajectory of the robot is generated in the presence of moving obstacles that is three times differentiable and enables direct derivation of kinematic level controls for the robot. A chained form decomposition and state transformation for a geometric and time criterion of collision avoidance is based on an approach where closed-form solution is found for a polynomial family of curves based on only one adjustable parameter for collision avoidance. However, the sensitivity of the parameter is considerable and can induce trajectories with large detours from the goal direction. Therefore, a family of curves based on B-splines is introduced here that enables better local curve shape control. Relative obstacles to robot movement determines the prohibited regions in the transformed space. Thereafter, a collision-free path is found by a line-segment expansion from the transformed start and goal configuration based on Rapidly-exploring Random Trees. Thus obtained path is further approximated by a B-spline curve resulting in the final smooth trajectory.

Keywords:

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Elzbieta Roszkowska

Abstract: The paper presents a DES-based controller for an emerging, important class of industrial and public transport media - guidepath-based, zone-controlled, closed traffic systems. We build upon and extend our earlier results concerning the formal methods of control synthesis. An essential requirement for the traffic flow in these systems is that the vehicles maintain their ability to access every location in the underlying guidepathnetwork, throughout the entire, presumably infinite, length of the system operation. The proposed construction ensures the required qualitative features of the control and gives a formal framework for the development of the computer-aided system that allows an experimental, simulation-based optimization of the parameters that decide about the system efficiency.

Keywords: guidepath-based traffic system,DES-based controller,liveness enforcement

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Elzbieta Jarzebowska, Rafal Lewandowski

Abstract: The paper presents a dynamic modeling and control design for a wheeled vehicle with idle wheels. An example we detail is a roller-racer. For this system, we cannot determine its global motion by just the shape variation, since it does not posses a sufficient number of nonholonomic constraint equations. Kinematics must be complemented with the system dynamics. Using the Boltzmann-Hamel equations we develop a control oriented dynamic model for the roller-racer. Based on this model we design a modified computed torque controller to track its desired motion. We demonstrate that the Boltzmann-Hamel equations offer a competitive tool to develop dynamic control models for constrained systems and they may facilitate a subsequent controller design.

Keywords: nonholonomic system dynamics,the Boltzmann-Hamel equations,motion tracking,computed torque controller

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Sven Gestegard Robertz, Anders Nilsson, Klas Nilsson, Mathias Haage

Abstract: For future robot control, there is a strong need for tools and methods supporting the development and deployment of control software. To this end, we propose a method for developing embedded software based on the standard Java language and multi-stage deployment and verification towards the embedded platform. The proposed method allows us to develop embedded Java software on the desktop using standard software tools for implementation, and the majority of testing and verification. The subsequent deployment is done in stages from pure Java to hard real-time embedded C. The source code of the application remains unchanged during all the stages, where components of the platform are changed one at a time. That makes it easier to find and cope with platform-related problems due to different run-time environments and thread models. As enabling technology we use the LJRT platform, a novel solution for hard real-time Java in embedded systems based on Java to C translation, real-time GC, and an off-the-shelf, real-time OS (e.g. Linux/RTAI). The proposed method has been experimentally tested in the development of a robot control application.

Keywords:

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006

Authors: Nelson R. S. Costa, Darwin G. Caldwell

Abstract: Currently many patients with brain/spinal cord/sport injuries or stroke, are confined to wheelchairs which results in many secondary conditions. Locomotor training attempts to encourage the patient to undertake walking exercises but the physical effort is such that there is poor compliance, as it requires a highly intensive and task-specific therapy approach. Powered Locomotor trainers aim to promote motor recovery, reducing this effort to a tolerable level encouraging higher levels of exercise, improved secondary health care and to obtain a better understanding of human motor walking gait. This paper will address the development and control of a lower limb exoskeleton for active assistive walking.

Keywords: exoskeleton,walking,control,rehabilitation,pneumatic muscle actuators,muscle

Identifier: None

Conference: Eighth International IFAC Symposium on Robot Control, 2006

Location: Santa Cristina Convent, University of Bologna, Italy

Start Date: Wed Sep 06 2006 - End Date: Fri Sep 08 2006