Robotic Machine for High-Quality Shotcrete Process

This paper summarizes the development of the technologies used to produce high quality sprayed concrete layers by robotizing a commercial shotcreting machine and automating the process used in the tunnelling construction industry. The proposed method provides the control system with the information of the properties of the pumping process, controlling the quality of the concrete layer by adjusting in real-time the trajectory of the shotcreting machine. Given the unstructured nature of the tunnelling construction method there is an inherent difficulty in the automation of the shotcreting process. A complete description of the implemented control architecture of the shotcreting machine, the automated shotcreting process, the real-time quality layer prediction and the analysis of the tests made in real sites are shown in this pape

Reliable, Built-in, High-Accuracy Force Sensing for Legged Robots

An approach for achieving reliable, built-in, high-accuracy force sensing for legged robots is presented, based on direct exploitation of the properties of a robot’s mechanical structure. The proposed methodology relies on taking account of force-sensing requirements at the robot design stage, with a view to embedding force-sensing capability within the mechanical structure of the robot itself. The test case is ROBOCLIMBER, a bulky, quadruped climbing and walking machine whose weighty legs enable it to carry out heavy-duty drilling operations. The paper shows that, with finite-element analysis of ROBOCLIMBER’s mechanical configuration during the design stage, candidate positions can be selected for the placement of force transducers to measure indirectly the contact forces between the feet and the ground. Force sensors are then installed at the theoretically best positions on the mechanical structure, and several experiments are carried out to calibrate all sensors within their operational range of interest. After calibration, the built-in sensors are subjected to experimental performance evaluation, and the final best sensor option is found. The built-in force-sensing capability thus implemented is subjected to its first test of usability when it is employed to compute the actual centre of gravity of ROBOCLIMBER. The method is shown to be useful for determining variation during a gait (due to the non-negligible weight of the legs). Afterwards the force sensors are shown to be useful for controlling foot-ground interaction, and several illustrative experiments confirm the high sensitivity, reliability and accuracy of the selected approach. Lastly, the built-in sensors are used to measure ground-reaction forces and to compute the zero-moment point for ROBOCLIMBER in real time, both while standing and while executing a dynamically balanced gait.An approach for achieving reliable, built-in, high-accuracy force sensing for legged robots is presented, based on direct exploitation of the properties of a robot’s mechanical structure. The proposed methodology relies on taking account of force-sensing requirements at the robot design stage, with a view to embedding force-sensing capability within the mechanical structure of the robot itself. The test case is ROBOCLIMBER, a bulky, quadruped climbing and walking machine whose weighty legs enable it to carry out heavy-duty drilling operations. The paper shows that, with finite-element analysis of ROBOCLIMBER’s mechanical configuration during the design stage, candidate positions can be selected for the placement of force transducers to measure indirectly the contact forces between the feet and the ground. Force sensors are then installed at the theoretically best positions on the mechanical structure, and several experiments are carried out to calibrate all sensors within their operational range of interest. After calibration, the built-in sensors are subjected to experimental performance evaluation, and the final best sensor option is found. The built-in force-sensing capability thus implemented is subjected to its first test of usability when it is employed to compute the actual centre of gravity of ROBOCLIMBER. The method is shown to be useful for determining variation during a gait (due to the non-negligible weight of the legs). Afterwards the force sensors are shown to be useful for controlling foot-ground interaction, and several illustrative experiments confirm the high sensitivity, reliability and accuracy of the selected approach. Lastly, the built-in sensors are used to measure ground-reaction forces and to compute the zero-moment point for ROBOCLIMBER in real time, both while standing and while executing a dynamically balanced gait

Reliable, built-in, high-accuracy force sensing for legged robots

An approach for achieving reliable, built-in, high-accuracy force sensing for legged robots is presented, based on direct exploitation of the properties of a robot's mechanical structure. The proposed methodology relies on taking account of force-sensing requirements at the robot design stage, with a view to embedding force-sensing capability within the mechanical structure of the robot itself. The test case is ROBOCLIMBER, a bulky, quadruped climbing and walking machine whose weighty legs enable it to carry out heavy-duty drilling operations. The paper shows that, with finite-element analysis of ROBOCLIMBER's mechanical configuration during the design stage, candidate positions can be selected for the placement of force transducers to measure indirectly the contact forces between the feet and the ground. Force sensors are then installed at the theoretically best positions on the mechanical structure, and several experiments are carried out to calibrate all sensors within their operational range of interest. After calibration, the built-in sensors are subjected to experimental performance evaluation, and the final best sensor option is found. The built-in force-sensing capability thus implemented is subjected to its first test of usability when it is employed to compute the actual centre of gravity of ROBOCLIMBER. The method is shown to be useful for determining variation during a gait (due to the non-negligible weight of the legs). Afterwards the force sensors are shown to be useful for controlling foot-ground interaction, and several illustrative experiments confirm the high sensitivity, reliability and accuracy of the selected approach. Lastly, the built-in sensors are used to measure ground-reaction forces and to compute the zero-moment point for ROBOCLIMBER in real time, both while standing and while executing a dynamically balanced gait. © 2006 SAGE Publication.Peer Reviewe

Diseño y control reactivo de robots caminantes sobre terreno natural

En las últimas décadas se ha constatado el creciente interés que presentan los robots caminantes, tanto desde el punto de vista de la investigación básica como de sus potenciales aplicaciones. Una de las principales características de los robots equipados con patas es su capacidad para poder desplazarse sobre una amplia variedad de terrenos no estructurados. Esta particularidad los hace muy atractivos e interesantes para su aplicación práctica como robots de servicios en los que se requiere la locomoción sobre terreno natural, el cual se caracteriza por presentar superficies irregulares, diversos tipos de obstáculos y distintas pendientes. Sin embargo, el caminar sobre terreno natural implica que tanto la geometría como las propiedades físicas de los elementos que rodean al robot son desconocidas y muy variables, por lo que es necesario dotar al robot de un sistema de control que adapte su comportamiento con respecto al entorno. Si bien el modelo del robot puede ser conocido con precisión razonable, resulta difícil obtener una descripción detallada del entorno, especialmente en lo que respecta a sus propiedades físicas. Por ello, se hace imprescindible el empleo de distintos sistemas que proporcionen información acerca de la interacción dinámica entre el robot y los elementos que le rodean. Dicha información deberá ser introducida de forma adecuada en el sistema de control. En esta tesis se aborda el problema de la locomoción sobre terreno natural de robots caminantes, y se proponen diversas soluciones para el control de la interacción robot-entorno basadas en arquitecturas de control reactivo. Para la realización de la tesis se ha elegido como plataforma experimental el robot Roboclimber, que es un robot cuadrúpedo, caminante y escalador, de grandes dimensiones, capaz de llevar consigo una carga muy elevada de equipo especializado para la consolidación de laderas de montañas rocosas.Partiendo del diseño, realización y modelado del robot y de su sistema de actuación servo-hidráulico, y definida su arquitectura de control, se investigan diversas alternativas para la obtención de las fuerzas de reacción robot-entorno, bien de forma indirecta empleando sensores de ultrasonidos, bien de forma directa mediante el empleo de sensores de presión localizados en los actuadores hidráulicos. Dado el elevado número de señales presentes y de la presencia de ruido en las medidas, se toman en consideración diversas técnicas de filtrado. Por otro lado, la generación de modos de locomoción estables sobre terreno natural es un problema complejo que requiere regular la interacción dinámica robot-entorno. Por esta razón se investigan diversas estrategias de control reactivo para locomoción sobre terreno natural, que van desde el control acomodaticio hasta el control de impedancia. Tanto para la implementación de las estrategias de control reactivo en tiempo real como para su evaluación experimental se ha empleado como plataforma a Roboclimber, con el que se han realizado pruebas exhaustivas y multitud de experimentos. Esta fase de experimentación ha servido también para evaluar la funcionalidad del robot en distintos tipos de situaciones con las que se va a tener que enfrentar habitualmente un robot de servicios que tiene que trabajar en ambientes y condiciones naturales, lo que significa, en la práctica, condiciones muy exigentes y de un grado de dificultad elevado. Aunque se haya empleado Roboclimber como plataforma de experimentación, muchos de los resultados obtenidos son de aplicabilidad, en general, al problema del control de robots caminantes sobre terreno natural

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An approach for achieving reliable, built-in, high-accuracy force sensing for legged robots is presented, based on direct exploitation of the properties of a robot’s mechanical structure. The proposed methodology relies on taking account of force-sensing requirements at the robot design stage, with a view to embedding force-sensing capability within the mechanical structure of the robot itself. The test case is ROBOCLIMBER, a bulky, quadruped climbing and walking machine whose weighty legs enable it to carry out heavy-duty drilling operations. The paper shows that, with finite-element analysis of ROBOCLIMBER’s mechanical configuration during the design stage, candidate positions can be selected for the placement of force transducers to measure indirectly the contact forces between the feet and the ground. Force sensors are then installed at the theoretically best positions on the mechanical structure, and several experiment

Real-time monitoring or the shotcreting process

The automation of the concrete spraying process is a key factor in both improving the working conditions and increasing productivity; as well as in contributing to the quality of sprayed concrete. The confidence in the quality of the automation process itself and of sprayed concrete linings thus produced can be improved by real time monitoring of pumping and other concrete-spraying-machine related technical parameters. The implementation on these machines of the innovation on-line monitoring and control techniques presented in thls chapter will have a substantial impact on the performance of sprayed concrete, decreasing the dispersion of results, increasing quality, having at the same time a positive impact on the safety of workers. They will also decrease the detection and reaction times if any dlsturbance in the concrete spraying process arises.Peer reviewe

A Method for Estimating Thickness of Sprayed Concrete Layers from Pumped Volume

It is known from experience that when spraying concrete it spreads on the wall, being the distribution of concrete around the axis depending -at the remaining factors constant- on nozzle designo The shape of these "spreadings" have been analysed by different authors [1][2], who shown that a relation between the cross section of single layer strips of sprayed concrete and the spraying process parameters exist. However, no analytical mode1s of this relationship have been found in the literature [1]. The way concrete spreads on the wall can be modelled using a statistical approach by introducing a spraying density function. This [continuous] density function represents the probability of a differential volume of sprayed concrete landing on a differential area around certain coordinates. In this paper a semi-empirical model of the spraying process, based on a parametric family of such density functions is presented. This model allows the estimation of sprayed concrete thickness from operational data (concrete and compressed air flow, distance to wall, nozzle trajectory and actual thickness of sprayed concrete, etc.) The calibration of the main parameters of the model using experimental data is also presented.Peer reviewe

Detecting Zero-Moment Point in Legged Robot

The study of Zero-moment point (ZMP) in ROBOCLIMBER (quadruped walking and climbing robot) was realized and calculated in real time during statically postural and dynamically balanced gait. Force sensor with strain gages was implemented on each foot bar of the robot in order to measure the ground reaction forces used for calculate the ZMP and to realize futures force control strategies. With the statically postural the ZMP was localized in order to know the point where the reaction force of the ground acts and so to know the distance between the geometric centre and the statically ZMP. When the robot realized one gait the ZMP was analyzed in order to identify if the ZMP was inside of support polygon. With this analysis it is possible to realize stables gaits with compliance movements.The study of Zero-moment point (ZMP) in ROBOCLIMBER (quadruped walking and climbing robot) was realized and calculated in real time during statically postural and dynamically balanced gait. Force sensor with strain gages was implemented on each foot bar of the robot in order to measure the ground reaction forces used for calculate the ZMP and to realize futures force control strategies. With the statically postural the ZMP was localized in order to know the point where the reaction force of the ground acts and so to know the distance between the geometric centre and the statically ZMP. When the robot realized one gait the ZMP was analyzed in order to identify if the ZMP was inside of support polygon. With this analysis it is possible to realize stables gaits with compliance movements

ROBOCLIMBER: Control System Architecture

The paper shows the complete system architecture of a walking and climbing robot developed to make slope consolidation, where heavy duty equipment is employed for drilling up to 20m holes. ROBOCLIMBER a quadruped robot whose development in founded under a Growth/Craft RTD project, and must operate on harsh conditions in order to make positioning and have to be capable of making the drilling tasks 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.The paper shows the complete system architecture of a walking and climbing robot developed to make slope consolidation, where heavy duty equipment is employed for drilling up to 20m holes. ROBOCLIMBER a quadruped robot whose development in founded under a Growth/Craft RTD project, and must operate on harsh conditions in order to make positioning and have to be capable of making the drilling tasks 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