Time filter

Source Type

Penedo F.,Autonomous University of Madrid | Haber R.E.,Autonomous University of Madrid | Haber R.E.,Center for Automation and Robotics | Gajate A.,Center for Automation and Robotics | Del Toro R.M.,Center for Automation and Robotics
IEEE Transactions on Industrial Informatics | Year: 2012

There is now an emerging need for an efficient modeling strategy to develop a new generation of monitoring systems. One method of approaching the modeling of complex processes is to obtain a global model. It should be able to capture the basic or general behavior of the system, by means of a linear or quadratic regression, and then superimpose a local model on it that can capture the localized nonlinearities of the system. In this paper, a novel method based on a hybrid incremental modeling approach is designed and applied for tool wear detection in turning processes. It involves a two-step iterative process that combines a global model with a local model to take advantage of their underlying, complementary capacities. Thus, the first step constructs a global model using a least squares regression. A local model using the fuzzy k-nearest-neighbors smoothing algorithm is obtained in the second step. A comparative study then demonstrates that the hybrid incremental model provides better error-based performance indices for detecting tool wear than a transductive neurofuzzy model and an inductive neurofuzzy model. © 2012 IEEE.

Villagra J.,Center for Automation and Robotics | Herrero-Perez D.,Technical University of Cartagena
IEEE Transactions on Control Systems Technology | Year: 2012

This work addresses the path tracking problem of industrial guidance systems used by automated guided vehicles (AGVs) in load transfer operations. We focus on the control law that permits to AGVs to operate tracking a predefined route with industrial grade of accuracy, repeatability and reliability. One of the main issues of this problem is related to the important weight variation of AGVs when transporting a load, which induces slipping and skidding effects. Besides, localization error of the guidance system should be taken into account because position estimation is typically performed at a low sample rate. Other key point is that control law oscillations can knock down the load, which gives rise to safety and performance problems. Three control techniquesfuzzy, vector pursuit and flatness-based controlare compared in order to evaluate how they can deal with these problems and satisfy the robustness requirements of such an industrial application. © 2011 IEEE.

Gajate A.,Center for Automation and Robotics | Bustillo A.,University of Burgos | Haber R.E.,Center for Automation and Robotics
International Journal of Innovative Computing, Information and Control | Year: 2012

This paper presents the design and implementation of an intelligent control system based on local neurofuzzy models of the milling process relayed through an Ethernet-based application. Its purpose is to control the spindle torque of a milling process by using an internal model control paradigm to modify the feed rate in real time. The stabilization of cutting torque is especially necessary in milling processes such as high-speed roughing of steel moulds and dies that present minor geometric uncertainties. Thus, maintenance of the cutting torque increases the material removal rate and reduces the risk of damage due to excessive spindle vibration, a very sensitive and expensive component in all high-speed milling machines. Torque control is therefore an interesting challenge from an industrial point of view. Direct and inverse local neurofuzzy models used in the internal model control paradigm are obtained through an identification process which uses representative input-output data from the system under study. These local neurofuzzy models are dynamically created online (for each new datum to be processed). Once obtained, the models that describe the dynamic process form the basis of the networked control system,. This methodology is successfully applied in a production environment, in order to demonstrate improvements in both performance and effectiveness. Two different industrial tasks are tested: roughing of slots and roughing of surfaces with sudden, unexpected height steps. In both cases the control system demonstrated its capability to avoid torque peaks that could lead to spindle damage while maintaining high productivity. © 2012 ICIC International.

Sanz-Merodio D.,Center for Automation and Robotics | Garcia E.,Center for Automation and Robotics | Gonzalez-De-Santos P.,Center for Automation and Robotics
Industrial Robot | Year: 2012

Purpose - Reducing energy consumption in walking robots is an issue of great importance in field applications such as humanitarian demining so as to increase mission time for a given power supply. The purpose of this paper is to address the problem of improving energy efficiency in statically stable walking machines by comparing two leg, insect and mammal, configurations on the hexapod robotic platform SILO6. Design/methodology/approach - Dynamic simulation of this hexapod is used to develop a set of rules that optimize energy expenditure in both configurations. Later, through a theoretical analysis of energy consumption and experimental measurements in the real platform SILO6, a configuration is chosen. Findings - It is widely accepted that the mammal configuration in statically stable walking machines is better for supporting high loads, while the insect configuration is considered to be better for improving mobility. However, taking into account the leg dynamics and not only the body weight, different results are obtained. In a mammal configuration, supporting body weight accounts for 5 per cent of power consumption while leg dynamics accounts for 31 per cent. Originality/value - As this paper demonstrates, the energy expended when the robot walks along a straight and horizontal line is the same for both insect and mammal configurations, while power consumption during crab walking in an insect configuration exceeds power consumption in the mammal configuration. © Emerald Group Publishing Limited.

Milanes V.,Center for Automation and Robotics | Villagra J.,Center for Automation and Robotics | Godoy J.,Center for Automation and Robotics | Simo J.,Rey Juan Carlos University | And 2 more authors.
IEEE Transactions on Intelligent Transportation Systems | Year: 2012

Vehicles equipped with intelligent systems designed to prevent accidents, such as collision warning systems (CWSs) or lane-keeping assistance (LKA), are now on the market. The next step in reducing road accidents is to coordinate such vehicles in advance not only to avoid collisions but to improve traffic flow as well. To this end, vehicle-to-infrastructure (V2I) communications are essential to properly manage traffic situations. This paper describes the AUTOPIA approach toward an intelligent traffic management system based on V2I communications. A fuzzy-based control algorithm that takes into account each vehicle's safe and comfortable distance and speed adjustment for collision avoidance and better traffic flow has been developed. The proposed solution was validated by an IEEE-802.11p-based communications study. The entire system showed good performance in testing in real-world scenarios, first by computer simulation and then with real vehicles. © 2011 IEEE.

Arevalo J.C.,Center for Automation and Robotics | Garcia E.,Center for Automation and Robotics
IEEE Transactions on Systems, Man and Cybernetics Part C: Applications and Reviews | Year: 2012

The application of impedance control strategies to modern legged locomotion is analyzed, paying special attention to the concepts behind its implementation which is not straightforward. In order to implement a functional impedance controller for a walking mechanism, the concepts of contact, impact, friction, and impedance have to be merged together. A literature review and a comprehensive analysis are presented compiling all these concepts along with a discussion on position-based versus force-based impedance control approaches, and a theoretical model of a robotic leg in contact with its environment is introduced. A theoretical control scheme for the legs of a general legged robot is also introduced, and some simulations results are presented. © 1998-2012 IEEE.

Galiana I.,Center for Automation and Robotics | Hammond F.L.,Harvard University | Howe R.D.,Harvard University | Popovic M.B.,Worcester Polytechnic Institute
IEEE International Conference on Intelligent Robots and Systems | Year: 2012

Stroke is the leading cause of long-term disability in the United States, affecting over 795,000 people annually. In order to regain motor function of the upper body, patients are usually treated by regular sessions with a dedicated physical therapist. A cost-effective wearable upper body orthotics system that can be used at home to empower both the patients and physical therapists is described. The system is composed of a thin, compliant, lightweight, cost-effective soft orthotic device with an integrated cable actuation system that is worn over the upper body, an embedded limb position sensing system, an electric actuator package and controller. The proposed device is robust to misalignments that may occur during actuation of the compliant brace or when putting on the system. Through simulations and experimental evaluation, it was demonstrated i) that the soft orthotic cable-driven shoulder brace can be successfully actuated without the production of off-axis torques in the presence of misalignments and ii) that the proposed model can identify linear and angular misalignments online. © 2012 IEEE.

Sanz-Merodio D.,Center for Automation and Robotics | Cestari M.,Center for Automation and Robotics | Arevalo J.C.,Center for Automation and Robotics | Garcia E.,Center for Automation and Robotics
International Journal of Advanced Robotic Systems | Year: 2012

By analysing the dynamic principles of the human gait, an economic gait-control analysis is performed, and passive elements are included to increase the energy efficiency in the motion control of active orthoses. Traditional orthoses use position patterns from the clinical gait analyses (CGAs) of healthy people, which are then de-normalized and adjusted to each user. These orthoses maintain a very rigid gait, and their energy cost is very high, reducing the autonomy of the user. First, to take advantage of the inherent dynamics of the legs, a state machine pattern with different gains in each state is applied to reduce the actuator energy consumption. Next, different passive elements, such as springs and brakes in the joints, are analysed to further reduce energy consumption. After an off-line parameter optimization and a heuristic improvement with genetic algorithms, a reduction in energy consumption of 16.8% is obtained by applying a state machine control pattern, and a reduction of 18.9% is obtained by using passive elements. Finally, by combining both strategies, a more natural gait is obtained, and energy consumption is reduced by 24.6% compared with a pure CGA pattern. © 2012 Sanz-Merodio et al.; licensee InTech.

Tejado I.,University of Extremadura | Milanes V.,Center for Automation and Robotics | Villagra J.,Center for Automation and Robotics | Vinagre B.M.,University of Extremadura
IEEE Transactions on Control Systems Technology | Year: 2013

This paper addresses the problem of e-safety driving in urban areas, where the principal limiting factor is vehicle-to-vehicle or vehicle-to-infrastructure communications. Time-varying network-induced delays constitute the main concern of networked control systems since they may negatively affect the velocity control of a vehicle at low speeds and consequently cause an accident. A system to adapt the vehicle's speed to avoid or mitigate possible accidents has been developed. In particular, gain scheduling is used in a local fractional-order proportional integral controller to compensate the effects of delay. Experimental results on a prototype Citroën vehicle in a real environment are presented, which demonstrate the effectiveness of the proposed system. © 1993-2012 IEEE.

Roldan J.J.,Center for Automation and Robotics | Del Cerro J.,Center for Automation and Robotics | Barrientos A.,Center for Automation and Robotics
2015 23rd Mediterranean Conference on Control and Automation, MED 2015 - Conference Proceedings | Year: 2015

The emergence of multi-UAV missions poses a set of challenges. The control and monitoring of these missions requires to increase the autonomy of fleets and to reduce the workload of operators. The development of an appropriate mission model is fundamental not only for specification and planning but also for control and monitoring. This model allows determining the mission and fleet states and, therefore, providing the operator with adequate information of the mission. This paper poses a methodology to develop multi-UAV mission models and analyzes different modeling techniques, such as Petri nets or hidden Markov models. © 2015 IEEE.

Loading Center for Automation and Robotics collaborators
Loading Center for Automation and Robotics collaborators