Anibal Ollero

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Papers by Anibal Ollero

Multiple UAV cooperative searching operation using polygon areadecomposition and efficient coverage algorithms

Distributed Autonomous Robotic Systems, 2004

This paper focuses on the problem of cooperatively searching a given area to detect objects of in... more This paper focuses on the problem of cooperatively searching a given area to detect objects of interest, using a team of heterogenous unmanned air vehicles (UAVs). The paper presents algorithms to divide the whole area taking into account UAV's relative capabilities and initial locations. Resulting areas are assigned among the UAVs, who could cover them using a zigzag pattern. Each UAV has to compute the sweep direction which minimizes the number of turns needed along a zigzag pattern. Algorithms are developed considering their computational complexity in order to allow near-real time operation. Results demonstrating the feasibility of the cooperative search in a scenario of the COMETS multi-UAV project are presented.

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Tutorial for the application of Kane's Method to model a small-size helicopter

by Luis A Sandino and Anibal Ollero

Proceedings of the first International Conference on Research, Development And Education On Unmanned Aerial Systems (RED-UAS11, Sevilla, SPAIN), Nov 30, 2011

Proceedings of the first International Conference on Research, Development And Education On Unman... more Proceedings of the first International Conference on Research, Development And Education On Unmanned Aerial Systems (RED-UAS11, Sevilla, SPAIN)

This paper presents a tutorial for applying Kane's method to derive a mechanical model of a small-size helicopter. Throughout this development main concepts underlying Kane's methodology are explained in detail. Furthermore, references to other approaches in the field of classical mechanics are included to analyze the advantages provided by Kane's method when compared to other alternatives. Since this work considers the most general case of two rigid bodies, fuselage and main rotor, the resulting model will account for most significant modelling issues in the mechanics behaviour of a small-size helicopter, such as gyroscopic effects. Finally it is emphasized that the adopted pedagogical approach should contribute to illustrate the method to beginners

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A Square-Root Unscented Kalman Filter for attitude and relative position estimation of a tethered unmanned helicopter

by Luis A Sandino, Konstantin Kondak, and Anibal Ollero

Proceedings of the 2015 International Conference On Unmanned Aircraft Systems (ICUAS15, Denver, USA), Jun 9, 2015

The use of tethered Unmanned Aircraft Systems (UAS) in aerial robotic applications is a relativel... more The use of tethered Unmanned Aircraft Systems (UAS) in aerial robotic applications is a relatively unexplored research field. In this work a numerically efficient implementation of a sigma-point Kalman filter is applied to the attitude and relative position estimation of a small-size tethered unmanned helicopter. For that purpose, the state prediction is performed using a kinematic process model driven by measurements of the inertial sensors (accelerometer and gyroscope) onboard the helicopter and the subsequent correction is done using information from additional sensors like magnetometer, radar altimeter and magnetic encoders measuring the tether orientation relative to the helicopter. Assuming the tether is kept taut by an actuated device on ground during the system operation, this approach avoids the need of a global positioning system (GPS) as the position is estimated relative to the anchor point. The filter performance is evaluated in simulations

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Fuzzy behaviors combination to control a nonholonomic mobile robot using virtual perception memory

by Begona Arrue and Anibal Ollero

Proceedings of 6th International Fuzzy Systems Conference, 1997

... rule based knowledge and sensors measurements, the interpolate nature of the fuzzy controller... more

Improving hovering performance of tethered unmanned helicopters with nonlinear control strategies

2013 International Conference on Unmanned Aircraft Systems (ICUAS), 2013

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Tether-guided landing of unmanned helicopters without GPS sensors

2014 IEEE International Conference on Robotics and Automation (ICRA), 2014

ABSTRACT Landing of unmanned helicopters is a challenging maneuver which can be seriously affecte... more ABSTRACT Landing of unmanned helicopters is a challenging maneuver which can be seriously affected by GPS sensor reliability. This work explores an alternative approach to GPS sensors to avoide typical drawbacks, such as inaccuracies of standalone sensors or weight/cost for RTK setups. To this end, the paper studies a setup consisting of a tether linking the helicopter to the landing point. Appropriate sensing of tether attitude relative to the helicopter together with an altitude measurement, allows estimation of the helicopter’s linear position relative to the landing point. Additionally, the tension exerted on the tether provides a stabilizing effect on helicopter translational dynamics. Taking into account all these considerations, a model-based control strategy is developed and implemented in the real platform. The experimental results endorse the validity of the proposed approach

Navigation with uncertain position estimation in the RAM1 mobile robot

Annual Review in Automatic Programming, 1994

This paper studies the uncertainty in mobile robot navigation. The paper presents a model to prop... more This paper studies the uncertainty in mobile robot navigation. The paper presents a model to propagate the uncertanty in position and orientation when tracking a given path. The model assumes normal distribution with zero means and a covariance matrix which can be computed recursively using the kinematics. The paper also presents the application to the mobile robot RAM-l designed and built for navigation in outdoor and indoor industrial environments. The proposed method can be used in the navigation system to know the position uncertainty before the vehicles executes a given path. Furthermore, the method is also useful to plan the execution of computationally intensive vision and other external perception functions which are required to avoid the uncertainty growing during navigation.

On the applicability of linear control techniques for autonomous landing of helicopters on the deck of a ship

2011 IEEE International Conference on Mechatronics, 2011

ABSTRACT

Dynamic Analysis of Weigthed-Output Fuzzy Control Systems

Artificial Intelligence in Real-Time Control 1994, 1995

In this paper, Fuzzy Control Systems with consecuent functions are analized using concepts from q... more In this paper, Fuzzy Control Systems with consecuent functions are analized using concepts from qualitative theory of nonlinear dynamic systems. Particularly, linear weigthed output fuzzy controllers and weight-output fuzzy controller are considered.The consequent function coefficients of rules around the equilibrium point are related with the stability and robusmess indices. Finally, a explanatory example is presented.

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Autonomous perception techniques for urban and industrial fire scenarios

2007 IEEE International Workshop on Safety, Security and Rescue Robotics, 2007

This paper presents autonomous perception techniques for disaster management and particularly for... more This paper presents autonomous perception techniques for disaster management and particularly for urban and industrial fire scenarios. The perception from static and mobile (on-board UAV) cameras is considered for smoke detection and cooperative tracking The algorithms used to achieve these functionalities will be described. The implementation of these techniques in the AWARE platform and the application in the general AWARE experiments to detect smoke and track firemen of the Seville fire brigades will also be presented.

Autonomous controller tuning by using a neural network

Lecture Notes in Computer Science

... I. INTRODUCTION This paper addresses the problem of controlling non linear systems from the s... more

6. Intelligent System for Parallel Parking of Cars and Tractor-Trailers

This chapter concentrates on practical maneuvering of electrical vehicles [68, 46]. Namely, auton... more This chapter concentrates on practical maneuvering of electrical vehicles [68, 46]. Namely, autonomous parking of vehicles with or without trailer is discussed, including planning and the use of fuzzy systems to improve the practical applicability of the methods. The autonomous vehicles used to illustrate the proposed methods, namely ROMEO-3R and ROMEO-4R, have been developed at the University of Seville as the result of the adaptation of a tricycle and a car-like conventional electrical vehicle for transportation of people, respectively [130].

A Survey on Methods for Elaborated Modeling of the Mechanics of a Small-Size Helicopter. Analysis and Comparison

Journal of Intelligent & Robotic Systems, 2013

ABSTRACT

On the use of tethered configurations for augmenting hovering stability in small-size autonomous helicopters

by Luis A Sandino and Anibal Ollero

Helicopters are well-known by their hovering capabilities. However, the performance of this valua... more Helicopters are well-known by their hovering capabilities. However, the performance of this valuable feature can be seriously affected by external disturbances such as wind effects. The latter could be even more significant when dealing with small-size helicopters, which are commonly adopted as base platforms for developing unmanned aerial vehicles. Motivated by this context, this work proposes an augmented configuration for performing more stable hovering maneuvers that consists of the unmanned helicopter itself, a tether connecting the helicopter to the ground, and a device on ground adjusting the tether tension. A modeling analysis on the inherent benefits to the proposed configuration as well as the control guidelines to exploit such potentialities are presented in this paper. As a proof a concept, a first basic implementation of the control structure for the entire system is also included. Finally, several demonstrating simulations under artificially generated wind influences are presented to endorse the validity of the proposed approach

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Advances in Modeling and Control of Tethered Unmanned Helicopters to Enhance Hovering Performance

Journal of Intelligent & Robotic Systems, 2013

ABSTRACT The hovering capabilities of unmanned helicopters can be seriously affected by wind. One... more ABSTRACT The hovering capabilities of unmanned helicopters can be seriously affected by wind. One possible solution for improving hovering performance under such circumstances is the use of a tethered setup that takes advantage of the tension exerted on the cable that links the helicopter to the ground. This paper presents a more elaborate strategy for helicopter control in this augmented setup, that extends previous work on the subject by the authors. Particularly, a combination of classical PID control laws, together with model inversion blocks, constitutes the basis of the new controller. Additionally, feed-forward action for counteracting rotational couplings is also taken into account. The resulting nonlinear control structure considers also a viscoelastic model of the tether which accurately reproduce the behavior of real ropes. Several simulations under artificially generated wind influences are presented to endorse the validity of the new proposed controller.

A mobile robot iconic position estimator using a radial laser scanner

Journal of Intelligent & Robotic Systems, 1995

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Stability analysis of nonlinear multivariable Takagi-Sugeno fuzzy control systems

IEEE Transactions on Fuzzy Systems, 1999

This paper points out how the nonlinearities involved in multivariable Takagi-Sugeno (T-S) fuzzy ... more This paper points out how the nonlinearities involved in multivariable Takagi-Sugeno (T-S) fuzzy control systems could originate complex behavior phenomena, such as multiple equilibrium points or limit cycles, that cannot be detected using conventional stability analysis techniques. In the paper, the application of MIMO frequency-domain methods to predict the existence of multiple equilibria and of limit cycles are presented. The proposed method is based on the formulation of a Lur'e problem from the original structure of a T-S fuzzy system with a fuzzy controller. Furthermore, this technique makes straightforward the application of input-output stability techniques such as the multivariable circle criterion, also called the conicity criterion, and the harmonic balance method. Moreover, in the paper, the application of the harmonic balance method has been generalized to the case of MIMO fuzzy system with asymmetric nonlinearities and improved by the decreasing conservatism. A new and more general stability index which could be used to perform a bifurcation analysis of fuzzy control systems is presented. The paper includes a collection of examples where the advantages of the proposed approach are made explicit comparing it to the input-output conicity criterion and the Lyapunov direct method.

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A robotic system for internal inspection of water pipelines

IEEE Robotics & Automation Magazine, 1999

This research has been motivated by the need for a reliable, robust, and cost-effective tool for ... more This research has been motivated by the need for a reliable, robust, and cost-effective tool for internal pipe inspection with application to preventive and predictive maintenance. A new design for a visual inspection system for the interior of water pipelines with minimal service interruption is presented. The method proposed is especially designed to work in the in-water environment. We first describe water pipelines and the challenges of navigation in their interior, and the current practices for failure detection are presented. We also present the mechanical design, the electronics and communication systems, the fiber-optic bus, and the operator station. Two image-processing algorithms for measuring fissure length and the effective diameter of the pipe are also presented, including examples of operation on real pipelines

Robust design of rule-based fuzzy controllers

Fuzzy Sets and Systems, 1995

This paper deals with the design of stable and robust rule-based fuzzy control systems. New expre... more This paper deals with the design of stable and robust rule-based fuzzy control systems. New expressions to compute indices which provide a measure of the stability and robustness of fuzzy control systems are presented. The relation between the modification of the rules and the stability is studied through the so-called sensitivity indices. The paper presents procedures that make use of these indices to improve the design of fuzzy control systems, including the modification of the rules to obtain the global stability of an unstable system with multiple attractors, and to improve the dynamic behavior or the robustness of a non-linear plant. An example with a fuzzy controller for a system with non-linear damping and saturation in the actuation is presented to illustrate the design procedure.

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Direct digital control, auto-tuning and supervision using fuzzy logic

Fuzzy Sets and Systems, 1989

... process is found in many industrial systems such as furnaces, boilers, air conditioning, etc ... more

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