有効なトルク制御が可能で安全なロボットのための可変トルクリミッタの設計と評価

早大学位記番号:新7966早稲田大

Magneto-Rheological Actuators for Human-Safe Robots: Modeling, Control, and Implementation

In recent years, research on physical human-robot interaction has received considerable attention. Research on this subject has led to the study of new control and actuation mechanisms for robots in order to achieve intrinsic safety. Naturally, intrinsic safety is only achievable in kinematic structures that exhibit low output impedance. Existing solutions for reducing impedance are commonly obtained at the expense of reduced performance, or significant increase in mechanical complexity. Achieving high performance while guaranteeing safety seems to be a challenging goal that necessitates new actuation technologies in future generations of human-safe robots. In this study, a novel two degrees-of-freedom safe manipulator is presented. The manipulator uses magneto-rheological fluid-based actuators. Magneto-rheological actuators offer low inertia-to-torque and mass-to-torque ratios which support their applications in human-friendly actuation. As a key element in the design of the manipulator, bi-directional actuation is attained by antagonistically coupling MR actuators at the joints. Antagonistically coupled MR actuators at the joints allow using a single motor to drive multiple joints. The motor is located at the base of the manipulator in order to further reduce the overall weight of the robot. Due to the unique characteristic of MR actuators, intrinsically safe actuation is achieved without compromising high quality actuation. Despite these advantages, modeling and control of MR actuators present some challenges. The antagonistic configuration of MR actuators may result in limit cycles in some cases when the actuator operates in the position control loop. To study the possibility of limit cycles, describing function method is employed to obtain the conditions under which limit cycles may occur in the operation of the system. Moreover, a connection between the amplitude and the frequency of the potential limit cycles and the system parameters is established to provide an insight into the design of the actuator as well as the controller. MR actuators require magnetic fields to control their output torques. The application of magnetic field however introduces hysteresis in the behaviors of MR actuators. To this effect, an adaptive model is developed to estimate the hysteretic behavior of the actuator. The effectiveness of the model is evaluated by comparing its results with those obtained using the Preisach model. These results are then extended to an adaptive control scheme in order to compensate for the effect of hysteresis. In both modeling and control, stability of proposed schemes are evaluated using Lyapunov method, and the effectiveness of the proposed methods are validated with experimental results

磁性流体を用いたバックドライブ可能な油圧アクチュエータの開発

早大学位記番号:新7478早稲田大

Conception et évaluation d’un simulateur à réalité virtuelle d’intervention laparoscopique actionné par des embrayages magnétorhéologiques

La laparoscopie est une technique chirurgicale qui offre une alternative moins invasive à la chirurgie abdominale traditionnelle, en permettant aux patients de récupérer plus rapidement et avec moins de douleur. Dès son arrivée, cette nouvelle technique a su révolutionner le monde de la chirurgie, mais cette révolution est d'ailleurs venue avec un cout, une formation longue et difficile. Des simulateurs haptiques ont tenté de rendre cet apprentissage plus facile, mais leur cout élevé et leurs grosses dimensions les rendent difficiles d'accès pour les étudiants moyens. Afin de résoudre ce problème, des concepts qui utilisent des dispositifs haptiques sont offerts sur le marché pour concevoir des plateformes de simulation d'interventions laparoscopiques. Ces plateformes sont toutefois peu fidèles à la réalité et n'atteignent pas simultanément les performances dynamiques et cinétiques nécessaires à un apprentissage adéquat. En effet, les moteurs électriques utilisés obligent les concepteurs de dispositifs haptiques à faire un compromis entre la force produite et la réponse dynamique du système. Cette approche pourrait par contre être utilisée avec un dispositif haptique nouvelle-génération, le T-Rex. Ce dernier a été développé récemment par Exonetik, une compagnie issue de recherches de l'Université de Sherbrooke. Contrairement aux dispositifs haptiques offerts sur le marché, le T-Rex utilise la technologie d'actionneurs magnéto-rhéologiques développée par Exonetik. Cette technologie pourrait permettre d'atteindre les performances dynamiques et cinétiques nécessaires à la formation de chirurgiens. Ce projet de recherche présente l'analyse préliminaire du T-Rex d'Exonetik en tant que simulateur à réalité virtuelle d'interventions laparoscopiques. Un simulateur à réalité virtuelle d'interventions laparoscopiques utilisant le T-Rex d'Exonetik en tant qu'interface haptique a été conçu. Des critères de performances ont été établis à l'aide de la littérature pour faire une évaluation quantitative du système. Des simulations utilisant la méthode des éléments finis ont aussi été développées pour faire une évaluation qualitative du système auprès de résidents et de chirurgiens. L'évaluation quantitative du système démontre qu'il répond aux quatre critères cinématiques ainsi qu'à trois des quatre critères cinétiques. Les résultats démontrent donc que l'utilisation d'actionneurs magnéto-rhéologiques dans les simulateurs à réalité virtuelle d'interventions laparoscopiques a beaucoup de potentiel. Par contre, la friction dans le système se doit d'être adressée dans les itérations futures du système

Comparative study of actuation systems for portable upper limb exoskeletons.

During the last two decades, a large variety of upper limb exoskeletons have been developed. Out of these, majority are platform based systems which might be the reason for not being widely adopted for post-stroke rehabilitation. Despite the potential benefits of platform-based exoskeletons as being rugged and reliable, stroke patients prefer to have a portable and user-friendly device that they can take home. However, the types of actuator as well as the actuation mechanism used in the exoskeleton are the inhibiting factors why portable exoskeletons are mostly non-existent for patient use. This paper presents a quantitative analysis of the actuation systems available for developing portable upper arm exoskeletons with their specifications. Finally, it has been concluded from this research that there are not many stand-alone arm exoskeletons which can provide all forms of rehabilitation, therefore, a generic solution has been proposed as the rehabilitation strategy to get best out of the portable arm exoskeletons

Advanced Mobile Robotics: Volume 3

Mobile robotics is a challenging field with great potential. It covers disciplines including electrical engineering, mechanical engineering, computer science, cognitive science, and social science. It is essential to the design of automated robots, in combination with artificial intelligence, vision, and sensor technologies. Mobile robots are widely used for surveillance, guidance, transportation and entertainment tasks, as well as medical applications. This Special Issue intends to concentrate on recent developments concerning mobile robots and the research surrounding them to enhance studies on the fundamental problems observed in the robots. Various multidisciplinary approaches and integrative contributions including navigation, learning and adaptation, networked system, biologically inspired robots and cognitive methods are welcome contributions to this Special Issue, both from a research and an application perspective

複数の静電容量型柔軟触覚デバイスを用いた三軸力センサの開発

早大学位記番号:新7325早稲田大

Elbow exoskeleton mechanism for multistage poststroke rehabilitation.

More than three million people are suffering from stroke in England. The process of post-stroke rehabilitation consists of a series of biomechanical exercises- controlled joint movement in acute phase; external assistance in the mid phase; and variable levels of resistance in the last phase. Post-stroke rehabilitation performed by physiotherapist has many limitations including cost, time, repeatability and intensity of exercises. Although a large variety of arm exoskeletons have been developed in the last two decades to substitute the conventional exercises provided by physiotherapist, most of these systems have limitations with structural configuration, sensory data acquisition and control architecture. It is still difficult to facilitate multistage post-stroke rehabilitation to patients sited around hospital bed without expert intervention. To support this, a framework for elbow exoskeleton has been developed that is portable and has the potential to offer all three types of exercises (external force, assistive and resistive) in a single structure. The design enhances torque to weight ratio compared to joint based actuation systems. The structural lengths of the exoskeleton are determined based on the mean anthropometric parameters of healthy users and the lengths of upperarm and forearm are determined to fit a wide range of users. The operation of the exoskeleton is divided into three regions where each type of exercise can be served in a specific way depending on the requirements of users. Electric motor provides power in the first region of operation whereas spring based assistive force is used in the second region and spring based resistive force is applied in the third region. This design concept provides an engineering solution of integrating three phases of post-stroke exercises in a single device. With this strategy, the energy source is only used in the first region to power the motor whereas the other two modes of exercise can work on the stored energy of springs. All these operations are controlled by a single motor and the maximum torque of the motor required is only 5 Nm. However, due to mechanical advantage, the exoskeleton can provide the joint torque up to 10 Nm. To remove the dependency on biosensor, the exoskeleton has been designed with a hardware-based mechanism that can provide assistive and resistive force. All exoskeleton components are integrated into a microcontroller-based circuit for measuring three joint parameters (angle, velocity and torque) and for controlling exercises. A user-friendly, multi-purpose graphical interface has been developed for participants to control the mode of exercise and it can be managed manually or in automatic mode. To validate the conceptual design, a prototype of the exoskeleton has been developed and it has been tested with healthy subjects. The generated assistive torque can be varied up to 0.037 Nm whereas resistive torque can be varied up to 0.057 Nm. The mass of the exoskeleton is approximately 1.8 kg. Two comparative studies have been performed to assess the measurement accuracy of the exoskeleton. In the first study, data collected from two healthy participants after using the exoskeleton and Kinect sensor by keeping Kinect sensor as reference. The mean measurement errors in joint angle are within 5.18 % for participant 1 and 1.66% for participant 2; the errors in torque measurement are within 8.48% and 7.93% respectively. In the next study, the repeatability of joint measurement by exoskeleton is analysed. The exoskeleton has been used by three healthy users in two rotation cycles. It shows a strong correction (correlation coefficient: 0.99) between two consecutive joint angle measurements and standard deviation is calculated to determine the error margin which comes under acceptable range (maximum: 8.897). The research embodied in this thesis presents a design framework of a portable exoskeleton model for providing three modes of exercises, which could provide a potential solution for all stages of post- stroke rehabilitation

Caracterización y estudio de sistemas con histéresis de tipo Bouc-Wen

En la presente Tesis de Máster se pretende plantear una metodologíıa para analizar y controlar sistemas con histéresis. Principalmente se estudiará el tipo de histéresis Bouc-Wen, y más concretamente técnicas de identificación de la misma basadas en algoritmos evolutivos. Una vez identificados los sistemas, se estudiarán diversas técnicas de control asíı como los posibles campos de aplicación de las mismas. Finalmente se plantean varios ejemplos de aplicación de estas técnicas de control en sistemas reales, tales como fibras SMA o un embrague magnetoreológico. Bajo el proyecto HYPER, todo lo aquí presentado pretende contribuir al diseño de dispositivos portátiles neuroprotésicos y neurorobóticos (NR-MNP) para ser utilizados, tanto para la rehabilitación, como para la compensación funcional de los trastornos motores en las actividades de la vida diaria. El objetivo final es superar las principales limitaciones de las soluciones actuales en rehabilitación.This Master Thesis pretends to define a methodology to analyse and control systems with hysteresis. It will be focus mainly on the Bouc-Wen model of hysteresis, and more specifically on identification techniques based on evolutive algorithms. Once the system has been identified, various techniques of control and possible fields of application will be stated. Finally, several application examples of these control techniques in real systems have been studied, such as SMA materials or a magnetorheological clutch. Under the HYPER project, everything presented in this document is intended to contribute to the design of neurorobotic and neuroprosthetics (NR-MNP) devices in order to be used both for rehabilitation and functional compensation of motor disorders in daily activities. The ultimate goal is to improve the current limitations of the classic rehabilitation devices.Máster Universitario en Robótica y AutomatizaciónSantiago Garrido Bullón; Concepción Monje Micharet; Dolores Blanco Roja