Authors: Joseph Nsasi Bakambu, Pierre Allard, Erick Dupuis

Abstract: This paper considers the problem of constructing a 3D environment model for space robotics applications. We presented our approach to 3D environment reconstruction from large sparse range data sets. In space robotics applications an accurate and up-to-date model of the environment is very important for variety of reasons. In particular, the model can be used for safe tele-operation, path planning and mapping of points of interest. We propose an on-line reconstruction of the environment using data provided by an on-board 3D range sensor LIDAR. The experiment results demonstrated the effectiveness of our approach in localization, path planning and following scenario on the Mars Yard located at Canadian Space Agency.

Keywords: mobile robot,autonomous navigation,3D localization,path planning

Identifier: 10.3182/20060906-3-IT-2910.00019

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: 10.3182/20060906-3-IT-2910.00057

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. Legnani, A. Visioli, G. Ziliani

Abstract: In this paper, the use of implicit (position based) and explicit hybrid force/velocity control for contour tracking task of unknown (planar) objects is discussed and compared from an industrial point of view. In particular, the joint friction compensation issue is addressed. A large number of experimental results obtained with a 2 degree-of-freedom SCARA industrial manipulator is shown to support the investigation.

Keywords: industrial robots,contour tracking,hybrid force/velocity control

Identifier: 10.3182/20060906-3-IT-2910.00043

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: Andrea Manni, Angelo di Noi, Giovanni Indiveri

Abstract: From the 1970's biped robots have had a large attention from the robotic research community. Yet the issue of controlling dynamically stable walking for arbitrary biped robots is still open. We propose a simple control architecture based on the use of the FRI (Foot Rotation Indicator) point and the support polygon. The major advantage of the proposed architecture is that motion planning (and eventually sensor based re-planning (slower feedback loop)) is limited to the leg joints whereas the trunk and arm degrees of freedom are controlled in closed loop (faster feedback loop) to achieve overall dynamic stability. Such architecture allows to decouple the problem of dynamic stable walking in the two relatively simpler problems of gait generation and robot stabilization. This architecture is particularly suited for small size robots having limited onboard computational power and limited sensor suits. The effectiveness of the proposed method has been validated through Matlab® simulations and experimental tests performed on a Robovie-MS platform.

Keywords: control architecture,dynamically stable gait,foot rotation indicator,support polygon

Identifier: 10.3182/20060906-3-IT-2910.00114

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: Carlos Henrique dos Santos, Guilherme Bittencourt, Raul Guenther, Edson De Pieri

Abstract: This paper investigates the possibility of applying a hybrid control with a fuzzy approach for redundancy resolution to an autonomous underwater vehicle-manipulator system (UVMS). The proposed algorithm generates a desired trajectory for the vehicle that takes into account the energy savings and the increase of system manipulability by a smooth actuation. Simulation results demonstrate the efficiency of this approach.

Keywords: hybrid systems,fuzzy logic,singularity,underwater vehicle-manipulator systems

Identifier: 10.3182/20060906-3-IT-2910.00100

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: 10.3182/20060906-3-IT-2910.00084

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: P. Arena, L. Fortuna, M. Frasca, L. Patane

Abstract: In this paper a new architecture based on a multi-layer analog/digital control system is introduced and applied to an autonomous hexapod robot. The robot structure that consists of 18 degrees of freedom, is controlled by a network of multiple interconnected modules. The system can be tele-operated by a PC through a wireless communication link but it can also operate autonomously by using the information gathered from the sensory system equipped on board. Therefore various methodologies on bio-robot control can be directly implemented and experimentally validated. A set of experimental tests was carried out to characterize the robot performance when employed to accomplish different tasks. The experimental results acquired during a collision avoidance task are also reported and discussed.

Keywords: autonomous hexapod robot,CNN-based CPG,navigation control,multi-layer hybrid structure

Identifier: 10.3182/20060906-3-IT-2910.00126

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: A. Zavala-Rio, V. Santibanez

Abstract: This work proposes a natural saturating extension of the PD with desired gravity compensation (PDdgc) control law for the global regulation of robot manipulators with bounded inputs. Compared to other algorithms previously proposed under the same analytical framework, it proves to be advantageous in several senses. First, it involves a single saturation function at each joint. Second, it does not need to discriminate the terms that shall be bounded since these are simply all of them included within the only saturation involved at every joint. Performance improvements with respect to previously proposed saturating approaches are corroborated through experimental results.

Keywords: global regulation,robot manipulators,bounded inputs,saturations

Identifier: 10.3182/20060906-3-IT-2910.00003

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: Luciene de Oliveira Marin, Mauro Roisenberg, Edson Roberto De Pieri

Abstract: This paper describes a neural network architecture and the online learning policies that permits to an autonomous robot navigates though a maze in order to memorize a path that explores the entire environment, while avoiding obstacles. The state space representation is constructed by unsupervised and competitive learning as well as the mapping state-action is constructed by means of reinforcement learning, during the maze exploration. The result of learning creates a memory of states-actions that emerges an intelligent behavior, such as the path learning. The robot uses only its own infrared distance-sensors to perform obstacle detection, used as pattern recognition cues, while moving in a maze environment. In order to demonstrate the effectiveness and real-time ability of the proposed neural controller, we report a number of simulation results of navigation in unknown maze environments.

Keywords: reactive navigation,mobile robots,ART - adaptive resonance theory,multi-layer perceptron,reinforcement learning,unsupervised learning,on-line learning

Identifier: 10.3182/20060906-3-IT-2910.00013

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 Caltabiano, Giovanni Muscato

Abstract: Planetary exploration rovers are often redundantly actuated, for mechanical robustness and reliability purposes. This paper describes the Integral Redistribution Traction Control Architecture (IR-TCA) applied to this category of robots. The Traction Control Architecture of mobile robots is typically composed by independent decoupled PID speed controllers, one for each motor. In this paper it will be demonstrated that this solution is not suitable in redundantly actuated robots. The IR-TCA is a hierarchical cross-coupled controller, a simple variation to the PID architecture, easily scalable for more complex systems. The stability of this Traction Control Architecture will also be demonstrated. Some comparative tests both with a simulator and a real platform will be presented to show the validity of this control architecture.

Keywords: traction control,mobile robots,control algorithms,controllers,PID,stability analysis

Identifier: 10.3182/20060906-3-IT-2910.00123

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: Alessandro Casavola, Michela Sorbara, Stefano Stramigioli

Abstract: In this paper an extension of the basic Command Governor approach for manipulation of dynamic systems is proposed. This work presents a way to incorporate kinetostatic feedback to the operator maintaining the passivity of the closed-loop system. Preliminary simulation results, without time-delay, are presented showing the theoretically expected effectiveness of the proposed method.

Keywords: constrained control,passivity,port-Hamiltonian systems

Identifier: 10.3182/20060906-3-IT-2910.00091

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: M. Fumagalli, P. Guagliardo, F. Fusco, A. Rusconi

Abstract: This paper presents a practical implementation of a collision avoidance algorithm that is based on the use of virtual forces, applied to a space robot composed of three arms, each one having seven degrees of freedom. To uniquely determine joint angles for a given end-effector position and orientation, the redundancy is parameterized by a scalar variable which corresponds to an angle between the arm plane and a reference plane. A pseudoinverse based kinematics is used to avoid problems due to singularity. A new control scheme is proposed with a discharge factor to control the transition between the free space and the obstacle threshold.

Keywords: collision,control,space,robot,manipulator,obstacle,forces,arm

Identifier: 10.3182/20060906-3-IT-2910.00122

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: Marina Indri

Abstract: A robust friction compensation approach is proposed, constituted by a feedback control law, including the compensation of the friction effects, on the basis of the estimate provided by a non model-based, reduced-order observer. The approach, developed in the paper to solve a regulation problem for a 1-dof servomechanism, does not require the knowledge of the friction parameters. The stability properties of the controlled system, and the robustness of the proposed control scheme with respect to variations of the system inertia, are analytically proven, and confirmed by simulation results.

Keywords: control techniques,friction compensation,non model-based control approach

Identifier: 10.3182/20060906-3-IT-2910.00029

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: Farhad Aghili, Mehrdad Namvar

Abstract: Joint-torque sensory feedback (JTF) can achieve precise robot control through a relatively simple control implementation, if accurate measurements of joint torques are available. This paper presents the development of an adaptive JTF control law that requires only the incorporation of uncalibrated joint torque signals, i.e., the gains and offsets of the torque sensors are unknown. Also, all physical parameters of the joints including the inertia of the rotors, link twist angles, and friction parameters are assumed unknowns to the controller. The robot dynamics with JTF is presented in a standard form with minimum number of parameters, where the inertia matrix appears symmetric and positive definite. Simulation and experimental results are presented to demonstrate disturbance rejection and tracking performance of the proposed adaptive JTF controller.

Keywords: joint torque feedback,adaptive control of manipulators,motion control,joint torque sensor

Identifier: 10.3182/20060906-3-IT-2910.00075

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: Jacopo Aleotti, Alessandro Melzi, Stefano Caselli

Abstract: This paper presents a virtual reality based system for programming mobile manipulation tasks. The system supports two modes of operation. The first mode implements a virtual reality interface for teleoperation, while the second mode is based on the programming by demonstration paradigm. The system exploits an advanced user interface allowing users with little or no technical expertise to integrate new tasks in a mobile robotic platform. The user can specify trajectories to be performed by the mobile base by means of a natural interface. Moreover the operator can supervise and validate the demonstrated task through a simulation module, thereby reducing errors in the generation process. Some experiments involving the whole set of system components demonstrate the viability and effectiveness of the approach.

Keywords: robot programming by demonstration,telemanipulation,virtual reality

Identifier: 10.3182/20060906-3-IT-2910.00066

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: M. L. Corradini, G. Sammarco

Abstract: In the present work, a virtual reality system, used in the framework of a web-based educational tool, is presented. Such tool, called VRL, can be used as a support for active learning of robotics in a web-learning environment. VRL guarantees forms of flexible learning, and couples virtual reality experiments, obtained through the integration of Matlab and Shockwave technology, and remote lab experiments, in order to allow a preliminary verification of theoretical concepts without the risks of damaging the remote experimental device.

Keywords: virtual reality,remote laboratory,active learning,robotics

Identifier: 10.3182/20060906-3-IT-2910.00069

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: 10.3182/20060906-3-IT-2910.00044

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: 10.3182/20060906-3-IT-2910.00095

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: Andrea Caiti, Andrea Munafo, Riccardo Viviani

Abstract: An adaptive on-line planning algorithm for multiple underwater vehicles in coastal oceanographic missions is introduced. The algorithm is tested for a team of autonomous underwater vehicles exploring an unknown oceanic environment in which they can execute point-wise environmental measurements. The team final objective is the construction of a three-dimensional estimated map of the measured environmental characteristics of the whole marine region. Each vehicle chooses its next sampling point in order to maximally increase the confidence level of the overall estimate of the measured quantity and in an asynchronous way with respect to the other vehicles. It is assumed that all vehicles have availability of the positions and values of the all past measurements executed by the members of the team. Simulative test cases in which the objective is the estimation of the ocean temperature over a region are presented. The algorithm performance is compared with that theoretically achievable by Rapidlyexploring Random Trees search.

Keywords: adaptive control,mobile robots,trajectory planning and control,underwater robots,vehicles

Identifier: 10.3182/20060906-3-IT-2910.00098

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: 10.3182/20060906-3-IT-2910.00074

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: Alicja Mazur, Marcin Kulawik

Abstract: In the paper a solution to adaptive trajectory tracking problem for doubly nonholonomic mobile manipulators has been presented. The proposed control algorithms take into considerations the kinematics as well as the dynamics of the whole nonholonomic system. Kinematic controller consists of two parts: Jiang & Nijmeijer controller for a nonholonomic manipulator and Samson controller for a mobile platform. Dynamic controllers preserve asymptotic trajectory tracking for the case of full knowledge of dynamic parameters and even with parametric uncertainty in dynamics. Theoretical considerations have been illustrated with simulations.

Keywords: nonholonomic constraints,adaptive control,trajectory tracking

Identifier: 10.3182/20060906-3-IT-2910.00076

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: 10.3182/20060906-3-IT-2910.00035

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: Alexander Winkler, Jozef Suchy

Abstract: This article presents an approach to robot force control for a compliant motion task with a commercial robot system. It consists of two parts: First is the algorithm for fast and sure environment contact detection. Second is the hybrid position/force control algorithm for contour following of an unknown surface. It contains the estimation of gradient of environment surface at contact point and the adaptation of working velocity. The approach is implemented in the robot controller and its functionality is shown on the drawing example task. The results of new algorithm are compared with results of the standard force control functions.

Keywords: robot control,force control,industrial robot,adaptation

Identifier: 10.3182/20060906-3-IT-2910.00085

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: Zotovic Ranko, Angel Valera Fernandez, Pedro Jose Garcia Gil, Angel Llosa Guillen

Abstract: An architecture for force and impact control is proposed. Its objectives are at first to control the robot in free motion until the contact with the environment is made. Next, it should make the transition phase as smooth as possible. Finally, it should switch to force control in order to assure the tracking of the force reference. An absolute priority is to protect the system against the dangerous peaks of force. Also, loss of contact should be avoided when possible. The performance is improved by taking care of the accumulation of elastic energy in the robot. Sampling period is changed depending on the state of the system. An experimental platform was developed in order to test the architecture.

Keywords: force control,impact control,impact,supervision,switching,discontinuous control

Identifier: 10.3182/20060906-3-IT-2910.00064

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: Qingguo Li, Shahram Payandeh

Abstract: In this paper, we study the manipulation planning problem for an ability-limited robot. The goal of manipulation is to push an object from an initial configuration to a goal configuration. The robot is restricted to perform only two kinds of motion in the plane. One is pushing the object forward with a constant and fixed velocity; The other one is rotating the object along a fixed-radius circle with a constant angular velocity. By the aid of optimal control theory, we prove that the optimal trajectory consists at most two switchings between these two actions. A planning method has been implemented to find the optimal trajectory. Manipulation examples are provided to demonstrate the proposed manipulation method.

Keywords: path planning,manipulation,optimal control,robotic manipulators controllability

Identifier: 10.3182/20060906-3-IT-2910.00015

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