3 research outputs found

    Design and implementation of a bristle bot swarm system

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    Swarm robotics focuses on the study and development of robot systems containing a large number of agents that interact with each other in a collective behaviour in order to achieve tasks or overcome obstacles. Bristlebots are vibration-driven mobile robots. They are characterized by small size, high speed, simple design and low costs for production and application – qualities which are advantageous for agents of swarm robotic systems. However, most studies have been developed over systems with no control or systems with two or more actuators. The aim of this master thesis is the development of a bristle based robot agent for a swarm robotics microsystem with units for locomotion, sensing, data processing, control, communication and energy storage. New approaches in modelling and development of swarm agents are given, and a robot prototype is presented. The robot is driven by a single DC motor and uses a bristle system to create locomotion. It should be noted, that within the system design, considerations for the size, weight and minimalist architecture are taken. Experiments are presented and the system’s capabilities for displacement, velocity and trajectory generation are analysed. While the parallel velocity maintains a positive magnitude in both motor rotation directions, the rotation speed and transversal velocity of the robot have opposite directions, creating curved trajectories with opposite orientations. In Frequencies up to 210 Hz, the rotation direction of the robot is maintained while the magnitude slightly varies. However, for higher frequencies, the rotation direction of the robot is reversed, maintaining a similar magnitude. The transversal speeds at this frequency range, maintain their direction but are clearly reduced compared to lower frequencies.Tesi

    Diseño e implementación de un robot móvil con una esfera de tracción omnidireccional

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    La utilización de robots móviles en el campo de la robótica industrial y la robótica de servicio es cada vez mayor. La mayoría de los diseños de estos robots móviles posen la denominada tracción diferencial. Esta no permite el movimiento omnidireccional y requiere de complejos algoritmos de control para la generación de trayectorias. Por otro lado, los robots que poseen tracción omnidireccional han sido poco estudiados. El objetivo de la tesis es diseñar e implementar un robot móvil con una esfera de tracción omnidireccional, que permita al robot realizar cambios repentinos de trayectoria sin tener que realizar giros. El robot tendrá una única esfera de tracción que será actuada por dos motores eléctricos. El control de los motores permitirá controlar el movimiento omnidireccional en el plano de desplazamiento del robot. El tamaño de la base del robot será de 10cm x 10cm y los motores eléctricos son controlados por un microcontrolador ATMEGA88PA y un controlador de motor L298 a través de señales moduladas por ancho de pulso (PWM). Se realizarán y documentarán diferentes experimentos de generación de movimiento (lateral, diagonal y circular) y en base a estos resultados el diseño del robot será evaluado.Tesi

    Optimally Controlling the Timing of Energy Transfer in Elastic Joints: Experimental Validation of the Bi-Stiffness Actuation Concept

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    Elastic actuation taps into elastic elements' energy storage for dynamic motions beyond rigid actuation. While Series Elastic Actuators (SEA) and Variable Stiffness Actuators (VSA) are highly sophisticated, they do not fully provide control over energy transfer timing. To overcome this problem on the basic system level, the Bi-Stiffness Actuation (BSA) concept was recently proposed. Theoretically, it allows for full link decoupling, while simultaneously being able to lock the spring in the drive train via a switch-and-hold mechanism. Thus, the user would be in full control of the potential energy storage and release timing. In this work, we introduce an initial proof-of-concept of Bi-Stiffness-Actuation in the form of a 1-DoF physical prototype, which is implemented using a modular testbed. We present a hybrid system model, as well as the mechatronic implementation of the actuator. We corroborate the feasibility of the concept by conducting a series of hardware experiments using an open-loop control signal obtained by trajectory optimization. Here, we compare the performance of the prototype with a comparable SEA implementation. We show that BSA outperforms SEA 1) in terms of maximum velocity at low final times and 2) in terms of the movement strategy itself: The clutch mechanism allows the BSA to generate consistent launch sequences while the SEA has to rely on lengthy and possibly dangerous oscillatory swing-up motions. Furthermore, we demonstrate that providing full control authority over the energy transfer timing and link decoupling allows the user to synchronously release both elastic joint and gravitational energy. This facilitates the optimal exploitation of elastic and gravitational potentials in a synergistic manner.Comment: 8 pages, 9 figures. Submitted to IEEE Robotics and Automation Letter
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