Kinesthetic Haptics Sensing and Discovery with Bilateral Teleoperation Systems

In the mechanical engineering field of robotics, bilateral teleoperation is a classic but still increasing research topic. In bilateral teleoperation, a human operator moves the master manipulator, and a slave manipulator is controlled to follow the motion of the master in a remote, potentially hostile environment. This dissertation focuses on kinesthetic perception analysis in teleoperation systems. Design of the controllers of the systems is studied as the influential factor of this issue. The controllers that can provide different force tracking capability are compared using the same experimental protocol. A 6 DOF teleoperation system is configured as the system testbed. An innovative master manipulator is developed and a 7 DOF redundant manipulator is used as the slave robot. A singularity avoidance inverse kinematics algorithm is developed to resolve the redundancy of the slave manipulator. An experimental protocol is addressed and three dynamics attributes related to kineshtetic feedback are investigated: weight, center of gravity and inertia. The results support our hypothesis: the controller that can bring a better force feedback can improve the performance in the experiments

Integration of the hybrid-structure haptic interface: HIPHAD v1.0

Design, manufacturing, integration and initial test results of the 6-DoF haptic interface, HIPHAD v1.0, are presented in this paper. The hybrid haptic robot mechanism is composed of a 3-DoF parallel platform manipulator, R-Cube, for translational motions and a 3-DoF serial wrist mechanism for monitoring the rotational motions of the handle. The device is capable of displaying point-type of contact since only the R-Cube mechanism is actuated. The dimensions and the orientation of the R-Cube mechanism are reconfigured to comply with the requirements of the haptic system design criteria. The system has several advantages such as relatively trivial kinematical analysis, compactness and high stiffness. The integration of the system along with its mechanism, data acquisition card (DAQ), motor drivers, motors, position sensors, and computer control interface are outlined.Marie Curie International Reintegration Grant within the 7th European Community Framework Programm

Design of a six degree-of-freedom haptic hybrid platform manipultor

Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2010Includes bibliographical references (leaves: 97-103)Text in English; Abstract: Turkish and Englishxv, 115 leavesThe word Haptic, based on an ancient Greek word called haptios, means related with touch. As an area of robotics, haptics technology provides the sense of touch for robotic applications that involve interaction with human operator and the environment. The sense of touch accompanied with the visual feedback is enough to gather most of the information about a certain environment. It increases the precision of teleoperation and sensation levels of the virtual reality (VR) applications by exerting physical properties of the environment such as forces, motions, textures. Currently, haptic devices find use in many VR and teleoperation applications. The objective of this thesis is to design a novel Six Degree-of-Freedom (DOF) haptic desktop device with a new structure that has the potential to increase the precision in the haptics technology. First, previously developed haptic devices and manipulator structures are reviewed. Following this, the conceptual designs are formed and a hybrid structured haptic device is designed manufactured and tested. Developed haptic device.s control algorithm and VR application is developed in Matlab© Simulink. Integration of the mechanism with mechanical, electromechanical and electronic components and the initial tests of the system are executed and the results are presented. According to the results, performance of the developed device is discussed and future works are addressed

A New Index for Detecting and Avoiding Type II Singularities for the Control of Non-Redundant Parallel Robots

[ES] Los robots paralelos (PR por sus siglas en inglés) son mecanismos donde el efector final está unido a la base, mediante al menos dos cadenas cinemáticas abiertas. Los PRs ofrecen una gran capacidad de carga y alta precisión, lo que los hace adecuados para diversas aplicaciones, entre ellas la interacción persona-robot. Sin embargo, en las proximidades de una singularidad Tipo II (singularidad dentro del espacio de trabajo), un PR pierde el control sobre los movimientos del efector final. La pérdida de control representa un riesgo importante para los usuarios, especialmente en rehabilitación robótica. En las últimas décadas, los PR se han popularizado en la rehabilitación de miembros inferiores debido al aumento del número de personas que viven con limitaciones físicas. Así, esta tesis trata sobre la detección y evitación de singularidades de Tipo II para asegurar total control de un PR no redundante para la rehabilitación y diagnóstico de rodilla, denominado 3UPS+RPU. En la literatura, existen varios índices para detectar y medir la cercanía a una singularidad basados en métodos analíticos y geométricos. Sin embargo, algunos de estos índices carecen de significado físico y son incapaces de identificar los actuadores responsables de la pérdida de control. Esta tesis aporta dos novedosos índices para detectar y medir la proximidad a una singularidad de Tipo II, capaces de identificar el par de actuadores responsables de la singularidad. Los dos índices son los ángulos entre los componentes lineal (T_i,j) y angular (O_i,j) de dos Twist Screw de Salida (OTS por sus siglas en inglés) normalizados i,j. Una singularidad Tipo II es detectada cuando T_i,j = O_i,j = 0 y su proximidad se mide mediante los mínimos ángulos T_i,j (minT) y O_i,j (minO) para los casos plano y espacial, respectivamente. La eficacia de los índices T_i,j y O_i,j se evalúa de forma teórica y experimental en un robot 3UPS+RPU y un mecanismo de cinco barras. Además, se propone un procedimiento experimental para el adecuado establecimiento del límite de cercanía a una singularidad de Tipo II mediante la aproximación progresiva del PR a una singularidad y la medición de la última posición controlable. Posteriormente, se desarrollan dos nuevos algoritmos deterministas para liberar y evitar una singularidad de Tipo II basados en minT y minO para PR no redundantes. minT y minO se utilizan para identificar los dos actuadores a mover para liberar o evitar el PR de una singularidad. Ambos algoritmos requieren una medición precisa de la pose alcanzada por el efector final. El algoritmo para liberar un PR de una configuración singular se aplica con éxito en un controlador híbrido basado en visión artificial para el PR 3UPS+RPU. El controlador utiliza un sistema de fotogrametría para medir la pose del robot debido a la degeneración del modelo cinemático en las proximidades de una singularidad. El algoritmo de evasión de singularidades Tipo II se aplica a la planificación offline y online de trayectorias no singulares para un mecanismo de cinco barras y el PR 3UPS+RPU. Estas aplicaciones verifican el bajo coste computacional y la mínima desviación introducida en la trayectoria original por los nuevos algoritmos. La implementación directa de un controlador de fuerza/posición en el PR 3UPS+RPU es insegura porque el paciente podría llevar involuntariamente al PR a una singularidad. Por lo tanto, esta tesis concluye presentando un novedoso controlador de fuerza/posición complementado con el algoritmo de evasión de singularidades de Tipo II. El nuevo controlador se evalúa durante rehabilitación activa de una pierna de maniquí y una pierna humana no lesionada. Los resultados muestran que el nuevo controlador combinado mantiene el PR 3UPS+RPU lejos de configuraciones singulares con una desviación mínima de la trayectoria original. Por lo tanto, esta tesis habilita el 3UPS+RPU PR para la rehabilitación segura de miembros inferiores lesionados.[CAT] Els robots paral·lels (PR per les seues sigles en anglés) són mecanismes on l'efector final està unit a la base, mitjançant almenys dues cadenes cinemàtiques obertes. Els PRs ofereixen una gran capacitat de càrrega i alta precisió, la qual cosa els fa adequats per a diverses aplicacions, entre elles la interacció persona-robot. No obstant això, en les proximitats d'una singularitat Tipus II (singularitat dins de l'espai de treball), un PR perd el control sobre els moviments de l'efector final. La pèrdua de control representa un risc important per als usuaris, especialment en rehabilitació robòtica. En les últimes dècades, els PR s'han popularitzat en la rehabilitació de membres inferiors a causa de l'augment del nombre de persones que viuen amb limitacions físiques. Així, aquesta tesi tracta sobre la detecció i evació de singularitats de Tipus II per a assegurar total control d'un PR no redundant per a la rehabilitació i diagnòstic de genoll, denominat 3UPS+RPU. En la literatura, existeixen diversos índexs per a detectar i mesurar la proximitat a una singularitat basats en mètodes analítics i geomètrics. No obstant això, alguns d'aquests índexs manquen de significat físic i són incapaços d'identificar els actuadors responsables de la pèrdua de control. Aquesta tesi aporta dos nous índexs per a detectar i mesurar la proximitat a una singularitat de Tipus II, capaços d'identificar el parell d'actuadors responsables de la singularitat. Els dos índexs són els angles entre els components lineal (T_i,j) i angular (O_i,j) de dues Twist Screw d'Eixida (OTS per les seues sigles en engonals) normalitzats i,j. Una singularitat Tipus II és detectada quan T_i,j = O_i,j = 0 i la seua proximitat es mesura mitjançant els minimos angles T_i,j (minT) i O_i,j (minO) per als casos pla i espacial, respectivament. L'eficàcia dels índexs T_i,j i O_i,j es evalua de manera teòrica i experimental en un robot 3UPS+RPU i un mecanisme de cinc barres. A més, es proposa un procediment experimental per a l'adequat establiment del límit de proximitat a una singularitat de Tipus II mitjançant l'aproximació progressiva del PR a una singularitat i el mesurament de l'última posició controlable. Posteriorment, es desenvolupen dos nous algorismes deterministes per a alliberar i evadir una singularitat de Tipus II basats en minT i minO per a PR no redundants. minT i minO s'utilitzen per a identificar els dos actuadors a moure per a alliberar o evadir el PR d'una singularitat. Aquests algorismes requereixen un mesurament precís de la posa aconseguida per l'efector final. L'algorisme per a alliberar un PR d'una configuració singular s'aplica amb èxit en un controlador híbrid basat en visió artificial per al PR 3UPS+RPU. El controlador utilitza un sistema de fotogrametria per a mesurar la posa del robot a causa de la degeneració del model cinemàtic en les proximitats d'una singularitat. L'algorisme d'evació de singularitats Tipus II s'aplica a la planificació offline i en línia de trajectòries no singulars per a un mecanisme de cinc barres i el PR 3UPS+RPU. Aquestes aplicacions verifiquen el baix cost computacional i la mínima desviació introduïda en la trajectòria original pels nous algorismes. La implementació directa d'un controlador de força/posició en el PR 3UPS+RPU és insegura perquè el pacient podria portar involuntàriament al PR a una singularitat. Per tant, aquesta tesi conclou presentant un nou controlador de força/posició complementat amb l'algorisme d'evació de singularitats de Tipus II. El nou controlador s'avalua durant la rehabilitació activa d'una cama de maniquí i una cama humana no lesionada. Els resultats mostren que el nou controlador combinat manté el PR 3UPS+RPU lluny de configuracions singulars amb una desviació mínima de la trajectòria original. Per tant, aquesta tesi habilita el 3UPS+RPU PR per a la rehabilitació segura dels membres inferiors lesionats.[EN] Parallel Robots (PR)s are mechanisms where the end-effector is linked to the base by at least two open kinematics chains. The PRs offer a high payload and high accuracy, making them suitable for various applications, including human robot interaction. However, in proximity to a Type II singularity (singularity within the workspace), a PR loses control over the movements of the end-effector. The loss of control represents a major risk for users, especially in robotic rehabilitation. In the last decades, PRs have become popular in lower limb rehabilitation because of the increment in the number of people living with physical limitations. Thus, this thesis is about the detection and avoidance of Type II singularities to ensure complete control of a non-redundant PR for knee rehabilitation and diagnosis named 3UPS+RPU. In the literature, several indices exist to detect and measure the closeness to a singular configuration based on analytical and geometrical methods. However, some of these indices have no physical meaning, and they are unable to identify the actuators responsible for the loss of control. This thesis contributes two novel indices to detect and measure the proximity to a Type II singularity capable of identifying the pair of actuators responsible for the singularity. The two indices are the angles between the linear (T_i,j) and the angular (O_i,j) components of two i,j normalised Output Twist Screws (OTSs). A Type II singularity is detected when the angles T_i,j = O_i,j = 0 and its closeness is measured by the minimum T_i,j (minT) and minimum O_i,j (minO) for planar and spatial cases, respectively. The effectiveness of the indices T_i,j and O_i,j is evaluated from a theoretical and experimental perspective in a 3UPS+RPU and a five bars mechanism. Moreover, an experimental procedure is proposed for setting a proper limit of closeness to a Type II singularity by the progressive approach of the PR to singular configuration and measuring the last controllable pose. Subsequently, two novel deterministic algorithms for releasing and avoiding Type II singularities based on minT and minO are developed for non-redundant PRs. The minT and minO are used to identify the two actuators to move for release or prevent the PR from the singularity. Both algorithms require an accurate measuring of the pose reached by the end-effector. The algorithm to release a PR from a singular configuration is successfully applied in a vision-based hybrid controller for the 3UPS+RPU PR. The controller uses a photogrammetry system to measure the pose of the robot due to the degeneration of the kinematic model in the vicinity of a singularity. The Type II singularity avoidance algorithm is applied to offline and online free-singularity trajectory planning for a five-bar mechanism and the 3UPS+RPU PR. These applications verify the low computation cost and the minimum deviation introduced in the original trajectory for both novel algorithms. The direct implementation of a force/position controller in the 3UPS+RPU PR is unsafe because the patient could unintentionally drive the PR to a Type II singularity. Therefore, this thesis concludes by presenting a novel force/position controller complemented with the Type II singularity avoidance algorithm. The complemented controller is evaluated during patient-active exercises in a mannequin leg and an uninjured human limb. The results show that the novel combined controller keeps the 3UPS+RPU PR far from singular configurations with a minimum deviation on the original trajectory. Hence, this thesis enables the 3UPS+RPU PR for the safe rehabilitation of injured lower limbs.Pulloquinga Zapata, JL. (2023). A New Index for Detecting and Avoiding Type II Singularities for the Control of Non-Redundant Parallel Robots [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/19427

Haptic Hand Exoskeleton for Precision Grasp Simulation

This paper outlines the design and the development of a novel robotic hand exoskeleton (HE) conceived for haptic interaction in the context of virtual reality (VR) and teleoperation (TO) applications. The device allows exerting controlled forces on fingertips of the index and thumb of the operator. The new exoskeleton features several design solutions adopted with the aim of optimizing force accuracy and resolution. The use of remote centers of motion mechanisms allows achieving a compact and lightweight design. An improved stiffness of the transmission and reduced requirements for the electromechanical actuators are obtained thanks to a novel principle for integrating speed reduction into torque transmission systems. A custom designed force sensor and integrated electronics are employed to further improve performances. The electromechanical design of the device and the experimental characterization are presented

Combining Sensors and Multibody Models for Applications in Vehicles, Machines, Robots and Humans

The combination of physical sensors and computational models to provide additional information about system states, inputs and/or parameters, in what is known as virtual sensing, is becoming increasingly popular in many sectors, such as the automotive, aeronautics, aerospatial, railway, machinery, robotics and human biomechanics sectors. While, in many cases, control-oriented models, which are generally simple, are the best choice, multibody models, which can be much more detailed, may be better suited to some applications, such as during the design stage of a new product

A demonstration and comparative analysis of haptic performance using a Gough-Stewart platform as a wearable haptic feedback device

In many hazardous work environments, contact tasks ranging from manufacturing to disassembly to emergency response are performed by industrial manipulators. Due to the hazardous and complex nature of these environments, teleoperation is often employed. When such is the case, the operator is left to interpret a large amount of data during task completion due to the complexity of modern robotic systems and the possible complexity of the tasks. This information is usually processed visually but can lead to sensory overload. To mitigate this, the information processing can also be distributed through other modes of sensory such as auditory or haptic. The University of Texas at Austin's TeMoto hands-free interface reduces the burden on the operator of commanding remote systems by enabling the use of gestural and verbal commands to complete a range of tasks, but the removal of a mechanical interactive device from the operator interface complicates the inclusion of haptic feedback. In this work, a standalone Gough-Stewart platform previously configured as a wearable haptic feedback device for the Nuclear and Applied Robotics Group at the University of Texas at Austin provides real-time haptic feedback to the unconstrained hand(s) of the operator. In doing so, this haptic interface can be employed with the intent of enhancing situational awareness and minimizing operator stress by imparting forces and torques to the user based on those imparted on the end-effector of the industrial manipulator. While multiple technical issues and human factor issues must be addressed, this effort focuses on integrating the system and evaluating its performance for various industrial manipulator designs and sensor modalities. After testing various digital signal processing techniques, functionality was demonstrated among one series-elastic and two rigid industrial manipulators, each with different force/torque data acquisition characteristics and a comparative analysis in haptic performance was performed. Furthermore, it was demonstrated with the TeMoto hands-free teleoperation system. Overall, the demonstrations and experiments performed in this work prove the system to be a viable, hardware agnostic means of haptic feedback and a strong basis for future effortsMechanical Engineerin

Multi-robot cooperative platform : a task-oriented teleoperation paradigm

This thesis proposes the study and development of a teleoperation system based on multi-robot cooperation under the task oriented teleoperation paradigm: Multi-Robot Cooperative Paradigm, MRCP. In standard teleoperation, the operator uses the master devices to control the remote slave robot arms. These arms reproduce the desired movements and perform the task. With the developed work, the operator can virtually manipulate an object. MRCP automatically generates the arms orders to perform the task. The operator does not have to solve situations arising from possible restrictions that the slave arms may have. The research carried out is therefore aimed at improving the accuracy teleoperation tasks in complex environments, particularly in the field of robot assisted minimally invasive surgery. This field requires patient safety and the workspace entails many restrictions to teleoperation. MRCP can be defined as a platform composed of several robots that cooperate automatically to perform a teleoperated task, creating a robotic system with increased capacity (workspace volume, accessibility, dexterity ...). The cooperation is based on transferring the task between robots when necessary to enable a smooth task execution. The MRCP control evaluates the suitability of each robot to continue with the ongoing task and the optimal time to execute a task transfer between the current selected robot and the best candidate to continue with the task. From the operator¿s point of view, MRCP provides an interface that enables the teleoperation though the task-oriented paradigm: operator orders are translated into task actions instead of robot orders. This thesis is structured as follows: The first part is dedicated to review the current solutions in the teleoperation of complex tasks and compare them with those proposed in this research. The second part of the thesis presents and reviews in depth the different evaluation criteria to determine the suitability of each robot to continue with the execution of a task, considering the configuration of the robots and emphasizing the criterion of dexterity and manipulability. The study reviews the different required control algorithms to enable the task oriented telemanipulation. This proposed teleoperation paradigm is transparent to the operator. Then, the Thesis presents and analyses several experimental results using MRCP in the field of minimally invasive surgery. These experiments study the effectiveness of MRCP in various tasks requiring the cooperation of two hands. A type task is used: a suture using minimally invasive surgery technique. The analysis is done in terms of execution time, economy of movement, quality and patient safety (potential damage produced by undesired interaction between the tools and the vital tissues of the patient). The final part of the thesis proposes the implementation of different virtual aids and restrictions (guided teleoperation based on haptic visual and audio feedback, protection of restricted workspace regions, etc.) using the task oriented teleoperation paradigm. A framework is defined for implementing and applying a basic set of virtual aids and constraints within the framework of a virtual simulator for laparoscopic abdominal surgery. The set of experiments have allowed to validate the developed work. The study revealed the influence of virtual aids in the learning process of laparoscopic techniques. It has also demonstrated the improvement of learning curves, which paves the way for its implementation as a methodology for training new surgeons.Aquesta tesi doctoral proposa l'estudi i desenvolupament d'un sistema de teleoperació basat en la cooperació multi-robot sota el paradigma de la teleoperació orientada a tasca: Multi-Robot Cooperative Paradigm, MRCP. En la teleoperació clàssica, l'operador utilitza els telecomandaments perquè els braços robots reprodueixin els seus moviments i es realitzi la tasca desitjada. Amb el treball realitzat, l'operador pot manipular virtualment un objecte i és mitjançant el MRCP que s'adjudica a cada braç les ordres necessàries per realitzar la tasca, sense que l'operador hagi de resoldre les situacions derivades de possibles restriccions que puguin tenir els braços executors. La recerca desenvolupada està doncs orientada a millorar la teleoperació en tasques de precisió en entorns complexos i, en particular, en el camp de la cirurgia mínimament invasiva assistida per robots. Aquest camp imposa condicions de seguretat del pacient i l'espai de treball comporta moltes restriccions a la teleoperació. MRCP es pot definir com a una plataforma formada per diversos robots que cooperen de forma automàtica per dur a terme una tasca teleoperada, generant un sistema robòtic amb capacitats augmentades (volums de treball, accessibilitat, destresa,...). La cooperació es basa en transferir la tasca entre robots a partir de determinar quin és aquell que és més adequat per continuar amb la seva execució i el moment òptim per realitzar la transferència de la tasca entre el robot actiu i el millor candidat a continuar-la. Des del punt de vista de l'operari, MRCP ofereix una interfície de teleoperació que permet la realització de la teleoperació mitjançant el paradigma d'ordres orientades a la tasca: les ordres es tradueixen en accions sobre la tasca en comptes d'estar dirigides als robots. Aquesta tesi està estructurada de la següent manera: Primerament es fa una revisió de l'estat actual de les diverses solucions desenvolupades actualment en el camp de la teleoperació de tasques complexes, comparant-les amb les proposades en aquest treball de recerca. En el segon bloc de la tesi es presenten i s'analitzen a fons els diversos criteris per determinar la capacitat de cada robot per continuar l'execució d'una tasca, segons la configuració del conjunt de robots i fent especial èmfasi en el criteri de destresa i manipulabilitat. Seguint aquest estudi, es presenten els diferents processos de control emprats per tal d'assolir la telemanipulació orientada a tasca de forma transparent a l'operari. Seguidament es presenten diversos resultats experimentals aplicant MRCP al camp de la cirurgia mínimament invasiva. En aquests experiments s'estudia l'eficàcia de MRCP en diverses tasques que requereixen de la cooperació de dues mans. S'ha escollit una tasca tipus: sutura amb tècnica de cirurgia mínimament invasiva. L'anàlisi es fa en termes de temps d'execució, economia de moviment, qualitat i seguretat del pacient (potencials danys causats per la interacció no desitjada entre les eines i els teixits vitals del pacient). Finalment s'ha estudiat l'ús de diferents ajudes i restriccions virtuals (guiat de la teleoperació via retorn hàptic, visual o auditiu, protecció de regions de l'espai de treball, etc) dins el paradigma de teleoperació orientada a tasca. S'ha definint un marc d'aplicació base i implementant un conjunt de restriccions virtuals dins el marc d'un simulador de cirurgia laparoscòpia abdominal. El conjunt d'experiments realitzats han permès validar el treball realitzat. Aquest estudi ha permès determinar la influencia de les ajudes virtuals en el procés d'aprenentatge de les tècniques laparoscòpiques. S'ha evidenciat una millora en les corbes d'aprenentatge i obre el camí a la seva implantació com a metodologia d'entrenament de nous cirurgians.Postprint (published version

Parallel robots with unconventional joints to achieve under-actuation and reconfigurability

The aim of the thesis is to define, analyze, and verify through simulations and practical implementations, parallel robots with unconventional joints that allow them to be under-actuated and/or reconfigurable. The new designs will be derived from the: * 6SPS robot (alternatively 6UPS or 6SPU, depending on the implementation) when considering the spatial case (i.e., robots with 3 degrees of freedom of rotation and 3 degrees of freedom of translation). * S-3SPS robot (alternatively S-3UPS or S-3SPU, depending on the implementation) when considering spherical robots (i.e., robots with 3 degrees of freedom of rotation). In both cases, we will see how, through certain geometric transformations, some of the standard joints can be replaced by lockable or non-holonomic joints. These substitutions permit reducing the number of legs (and hence the number of actuators needed to control the robot), without losing the robot's ability to bring its mobile platform to any position and orientation (in case of a spatial robot), or to any orientation (in case of a spherical robot), within its workspace. The expected benefit of these new designs is to obtain parallel robots with: * larger working spaces because the possibility of collisions between legs is reduced, and the number of joints (with their intrinsic range limitations) is also reduced; * lower weight because the number of actuators and joints is reduced; and * lower cost because the number of actuators and controllers is also reduced. The elimination of an actuator and the introduction of a motion constraint reduces in one the dimension of the space of allowed velocities attainable from a given configuration. As a result, it will be necessary, in general, to plan maneuvers to reach the desired configuration for the moving platform. Therefore, the obtained robots will only be suitable for applications where accuracy is required in the final position and a certain margin of error is acceptable in the generated trajectories.El objetivo de esta tesis es definir, analizar y verificar, mediante simulaciones e implementaciones prácticas, robots paralelos con articulaciones no-convencionales con el fin de incorporarles propiedades de sub-actuación y reconfigurabilidad. Los nuevos diseños se basaran en robots paralelos tipo: * 6SPS (alternativamente 6UPS o 6SPU, dependiendo de la implementación) para el caso de robot espacial (es decir, robots con 3 grados de libertad de rotación y de 3 grados de libertad de la traducción). * S-3SPS (alternativamente S-3UPS o S-3SPU, dependiendo de la implementación) para el caso de robot esférico (es decir, robots con 3 grados de libertad de rotación). En ambos casos, veremos cómo, a través de ciertas transformaciones geométricas, algunas de la articulaciones convencionales pueden ser sustituidas por articulaciones bloqueables o no holonómicos. Estas sustituciones permiten la reducción de la número de patas (y por tanto el número de actuadores necesarios para controlar el robot), sin perder la capacidad del robot para llevar su plataforma móvil a cualquier posición y orientación (en el caso de un robot espacial), o para cualquier orientación (en el caso de un robot esférico), dentro de su espacio de trabajo. El beneficio esperado de estos nuevos diseños es la obtención de robots paralelos con: * Espacios de trabajo mayores debido a que la posibilidad de colisiones entre las patas se reduce, y el número de articulaciones (con sus limitaciones intrínsecas de rango) también se reduce; * Menor peso debido a que el número de actuadores y de articulaciones se reduce; y * Un menor coste debido a que el número de actuadores y controladores también se reduce. La eliminación de un actuador y la introducción de una restricción de movimiento reduce, en uno, la dimensión del espacio de velocidades alcanzables para una configuración dada. Como resultado, será necesario, en general, planificar maniobras para llegar a la configuración deseada de la plataforma móvil. Por lo tanto, los robots obtenidos sólo serán adecuados para aplicaciones donde la precisión se requiera en la posición final y exista un cierto margen de error aceptable en las trayectorias generadasPostprint (published version

Parallel robots with unconventional joints to achieve under-actuation and reconfigurability

The aim of the thesis is to define, analyze, and verify through simulations and practical implementations, parallel robots with unconventional joints that allow them to be under-actuated and/or reconfigurable. The new designs will be derived from the: * 6SPS robot (alternatively 6UPS or 6SPU, depending on the implementation) when considering the spatial case (i.e., robots with 3 degrees of freedom of rotation and 3 degrees of freedom of translation). * S-3SPS robot (alternatively S-3UPS or S-3SPU, depending on the implementation) when considering spherical robots (i.e., robots with 3 degrees of freedom of rotation). In both cases, we will see how, through certain geometric transformations, some of the standard joints can be replaced by lockable or non-holonomic joints. These substitutions permit reducing the number of legs (and hence the number of actuators needed to control the robot), without losing the robot's ability to bring its mobile platform to any position and orientation (in case of a spatial robot), or to any orientation (in case of a spherical robot), within its workspace. The expected benefit of these new designs is to obtain parallel robots with: * larger working spaces because the possibility of collisions between legs is reduced, and the number of joints (with their intrinsic range limitations) is also reduced; * lower weight because the number of actuators and joints is reduced; and * lower cost because the number of actuators and controllers is also reduced. The elimination of an actuator and the introduction of a motion constraint reduces in one the dimension of the space of allowed velocities attainable from a given configuration. As a result, it will be necessary, in general, to plan maneuvers to reach the desired configuration for the moving platform. Therefore, the obtained robots will only be suitable for applications where accuracy is required in the final position and a certain margin of error is acceptable in the generated trajectories.El objetivo de esta tesis es definir, analizar y verificar, mediante simulaciones e implementaciones prácticas, robots paralelos con articulaciones no-convencionales con el fin de incorporarles propiedades de sub-actuación y reconfigurabilidad. Los nuevos diseños se basaran en robots paralelos tipo: * 6SPS (alternativamente 6UPS o 6SPU, dependiendo de la implementación) para el caso de robot espacial (es decir, robots con 3 grados de libertad de rotación y de 3 grados de libertad de la traducción). * S-3SPS (alternativamente S-3UPS o S-3SPU, dependiendo de la implementación) para el caso de robot esférico (es decir, robots con 3 grados de libertad de rotación). En ambos casos, veremos cómo, a través de ciertas transformaciones geométricas, algunas de la articulaciones convencionales pueden ser sustituidas por articulaciones bloqueables o no holonómicos. Estas sustituciones permiten la reducción de la número de patas (y por tanto el número de actuadores necesarios para controlar el robot), sin perder la capacidad del robot para llevar su plataforma móvil a cualquier posición y orientación (en el caso de un robot espacial), o para cualquier orientación (en el caso de un robot esférico), dentro de su espacio de trabajo. El beneficio esperado de estos nuevos diseños es la obtención de robots paralelos con: * Espacios de trabajo mayores debido a que la posibilidad de colisiones entre las patas se reduce, y el número de articulaciones (con sus limitaciones intrínsecas de rango) también se reduce; * Menor peso debido a que el número de actuadores y de articulaciones se reduce; y * Un menor coste debido a que el número de actuadores y controladores también se reduce. La eliminación de un actuador y la introducción de una restricción de movimiento reduce, en uno, la dimensión del espacio de velocidades alcanzables para una configuración dada. Como resultado, será necesario, en general, planificar maniobras para llegar a la configuración deseada de la plataforma móvil. Por lo tanto, los robots obtenidos sólo serán adecuados para aplicaciones donde la precisión se requiera en la posición final y exista un cierto margen de error aceptable en las trayectorias generada