Using a 3DOF Parallel Robot and a Spherical Bat to hit a Ping-Pong Ball

Playing the game of Ping-Pong is a challenge to human abilities since it requires developing skills, such as fast reaction capabilities, precision of movement and high speed mental responses. These processes include the utilization of seven DOF of the human arm, and translational movements through the legs, torso, and other extremities of the body, which are used for developing different game strategies or simply imposing movements that affect the ball such as spinning movements. Computationally, Ping-Pong requires a huge quantity of joints and visual information to be processed and analysed, something which really represents a challenge for a robot. In addition, in order for a robot to develop the task mechanically, it requires a large and dexterous workspace, and good dynamic capacities. Although there are commercial robots that are able to play Ping-Pong, the game is still an open task, where there are problems to be solved and simplified. All robotic Ping-Pong players cited in the bibliography used at least four DOF to hit the ball. In this paper, a spherical bat mounted on a 3-DOF parallel robot is proposed. The spherical bat is used to drive the trajectory of a Ping-Pong ball.Fil: Trasloheros, Alberto. Universidad Aeronáutica de Querétaro; MéxicoFil: Sebastián, José María. Universidad Politécnica de Madrid; España. Consejo Superior de Investigaciones Científicas; EspañaFil: Torrijos, Jesús. Consejo Superior de Investigaciones Científicas; España. Universidad Politécnica de Madrid; EspañaFil: Carelli Albarracin, Ricardo Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Automática. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Automática; ArgentinaFil: Roberti, Flavio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Automática. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Automática; Argentin

Trading-off reliability and performance in FPGA-based reconfigurable heterogeneous systems

Recent years have witnessed the rapid growth of heterogeneous systems, composed of CPUs and hardware accelerators, to face up the constant increase of computational performance demand of digital systems. In this scenario, FPGAs offer the possibility to implement high performance reconfigurable accelerators, able to speed up the intrinsically parallel portions of applications. The study of reconfigurable heterogeneous systems is still maturing and, while some contributions about performance and power consumption are available, in literature there are few works addressing reliability. This paper analyzes reconfigurable heterogeneous systems in presence of permanent faults occurring in the FPGA. In this context, a reconfigurable heterogeneous architecture, including a Run Time Manager responsible for the communication of software tasks and the FPGA, the scheduling and the placement of hardware tasks, is presented. In addition, the paper introduces a reconfigurable heterogeneous system simulator for the proposed architecture. This simulator is able to evaluate during the design phase the degradation of the system performance due to permanent faults and allows to explore the design space dimensions efficiently

Shielding Performance Monitor Counters: A double edged weapon for safety and security

Recent years have witnessed the growth of the adoption of Cyber-Physical Systems (CPSs) in many sectors such as automotive, aerospace, civil infrastructures and healthcare. Several CPS applications include critical scenarios, where a failure of the system can lead to catastrophic consequences. Therefore, anomalies due to failure or malicious attacks must be timely detected. This paper focuses on two relevant aspects of the design of a CPS: safety and security. In particular, it studies how performance monitor counters (PMCs) available in modern microprocessors can be from the one hand a valuable tool to enhance the safety of a system and, on the other hand, a security backdoor. Starting from the example of a PMC based safety mechanism, the paper shows the implementation of a possible attack and eventually proposes a strategy to mitigate the effectiveness of the attack while preserving the safeness of the system

Performance monitor counters: Interplay between safety and security in complex cyber-physical systems

Recent years have witnessed the growth of the adoption of cyber-physical systems (CPSs) in many sectors, such as automotive, aerospace, civil infrastructures, and healthcare. Several CPS applications include critical scenarios, where a failure of the system can lead to catastrophic consequences. Therefore, anomalies due to failures or malicious attacks must be detected timely. This paper focuses on two relevant aspects of the design of a CPS: 1) safety and 2) security. It analyzes in a specific scenario how the performance monitor counters (PMCs) available in several commercial microprocessors can be from the one hand a valuable tool to enhance the safety of a system and, on the other hand, a security backdoor. Starting from the example of a PMC-based safety mechanism, this paper shows the implementation of a possible attack and eventually proposes a strategy to mitigate the effectiveness of the attack while preserving the safety of the system

Visual Servoing for the Robotenis System: a Strategy for a 3 DOF Parallel Robot to Hit a Ping-Pong Ball

This article describes a new visual servo control and strategies that are used to carry out dynamic tasks by the Robotenis platform. This platform is basically a parallel robot that is equipped with an acquisition and processing system of visual information, its main feature is that it has a completely open architecture control, and planned in order to design, implement, test and compare control strategies and algorithms (visual and actuated joint controllers). Following sections describe a new visual control strategy specially designed to track and intercept objects in 3D space. The results are compared with a controller shown in previous woks, where the end effector of the robot keeps a constant distance from the tracked object. In this work, the controller is specially designed in order to allow changes in the tracking reference. Changes in the tracking reference can be used to grip an object that is under movement, or as in this case, hitting a hanging Ping-Pong ball. Lyapunov stability is taken into account in the controller design

Control Visual Dinámico en una PKM para el Seguimiento y Golpeo de una Pelota de Ping-Pong

En el presente trabajo se describe un controlador innovador que es utilizado en la realización de tareas dinámicas con aplicación en la plataforma Robotenis. Esta plataforma está compuesta principalmente por un robot paralelo dotado de un sistema de adquisición y procesamiento visual. La plataforma Robotenis tiene una arquitectura de control abierta con el objetivo de diseñar, implementar y comparar estrategias de control visual y articular. En las siguientes secciones se describe una nueva estrategia de control visual, especialmente diseñada para el seguimiento de objetos dinámicos en el espacio tridimensional. En contraste con estrategias estudiadas en trabajos previos, donde la referencia de control es constante, en este trabajo se contemplan referencias dinámicas de seguimiento. Mediante este controlador, los cambios de referencia pueden ser utilizados para sujetar objetos bajo movimiento o como en nuestro caso para golpear una pelota de ping-pong. En el diseño del controlador se realiza un análisis de estabilidad por Lyapunov

One Camera in Hand for Kinematic Calibration of a Parallel Robot

The main purpose of robot calibration is the correction of the possible errors in the robot parameters. This paper presents a method for a kinematic calibration of a parallel robot that is equipped with one camera in hand. In order to preserve the mechanical configuration of the robot, the camera is utilized to acquire incremental positions of the end effector from a spherical object that is fixed in the word reference frame. Incremental positions of the end effector are related to incremental positions of encoders of the motors of the robot. A kinematic model of the robot is modified in order to take into account possible errors of kinematic parameters. The solution of the model utilizes incremental positions of the resolvers and end effector, the new parameters minimizes errors in the kinematic equations. Spherical properties and intrinsic camera parameters are utilized to model sphere projection in order to improve spatial measurements. The robot system is designed to carry out tracking tasks and the calibration of the system is finally validated by means of integrating the errors of the visual controller

Homography-Based Tracking Control for Mobile Robots

This work presents a control strategy that allows a follower robot to track a target vehicle moving along an unknown trajectory with unknown velocity. It uses only artificial vision to establish both the robot’s position and orientation relative to the target. The control system is proved to be asymptotically stable at the equilibrium point, which corresponds to the navigation objective. Experimental results with two robots, a leader and a follower, are included to show the performance of the proposed vision-based tracking control system

Dynamic Visual Servoing for Ping-Pong Game of a 3DOF PKM

This article describes the new visual servo control and strategies that are utilized to carry out dynamic tasks by the system Robotenis. This platform is a parallel robot that is equipped with an acquisition and processing system of visual information. Its main feature is that it has a completely open architecture control, planned in order to design, implement, test and compare control strategies and algorithms (visual and actuated joint controllers). Following sections describe a new visual control strategy specially designed to track dynamic objects in 3D space. Contrasting the strategies shown in previous works, where the end effect or of the robot keeps a constant distance from the tracked object, in this work the controller is specially designed in order to allow changes the tracking reference. Changes in the tracking reference can be utilized to grip an object that is under movement or as in this case, Ping-Pong playing. Lyapunov stability is taken into account in the controller design