45 research outputs found

    Pneumatic muscle actuators within robotic and mechatronic systems

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    Artificial Muscles for Humanoid Robots

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    3D Modelling and design of a bioloid compliant quadruped leg

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    Dissertação de mestrado integrado em Engenharia BiomédicaIn the growing fields of rehabilitation robotics, prosthetics, and walking robots, the modeling of a real robot is a complex and passionate challenge. On the crossing point of mechanics, physics and computer-science, the development of a complete model involves multiple tasks ranging from the 3D modeling of the different body parts, the measure of the different physic properties, the understanding of the requirements for an accurate simulation, to the development of a robotic controller. In order to minimize large forces due to shocks, to safely interact with the user or the environment, and knowing the ability of passive elastic elements to store and release energy, compliant mechanisms are increasingly being applied in robots applications. This work aims to the elaboration of an accurate efficient three-dimensional model of the legs of the quadruped Bioloid robot and the development of a world showing the effect on WebotsTM simulation software developed by Cyberbotics Ltd. The goal was to design a segmented pantographic leg with compliant joints, in order to actively retract the collision and the impact of the quadruped legs with the ground during locomotion. Geometrical and mechanical limits have to be evaluated and considered for the modeling setup. Finally a controller based on the use of Central Pattern Generators was improved in order to adapt to the novel model and simple tests were performed in the WebotsTM, rendering a 3D model simulation for the different values of spring-damping coefficients at the legs knee joint. Through the a MATLAB® algorithm, the characterization of the joint angles during simulation was possible to be assessed.A modelação de um robot real é um desafio complexo e fascinante na crescente área da Robótica, que engloba desde robots de reabilitação, próteses a uma diversidade de outros dispositivos locomotores. No cruzamento da mecânica com a física e as ciências computacionais, o desenvolvimento de um modelo completo envolve várias tarefas que vão desde a modelação 3D das diferentes partes do corpo, a medição das propriedades físicos inerentes, a compreensão dos requisitos para uma simulação precisa bem como a aplicação de um controlador robótico. A fim de minimizar grandes forças devido a choques, interagir com segurança com o utilizador ou o ambiente e conhecendo a capacidade de armazenagem de energia por parte de elementos elásticos passivos, um sistema de amortecimento-mola demonstra ser uma aplicação de crescente interesse na Robótica. Este trabalho visa a elaboração de um modelo tridimensional eficiente e preciso das pernas do robô quadrúpede Bioloid a ser reproduzido num mundo no software WebotsTM desenvolvido pela Cyberbotics Ltd. O objectivo foi desenhar uma perna pantográfica segmentada tridimensional a ser aplicada em paralelo com um sistema de amortecimento-mola de forma a retrair activamente a colisão e o impacto das patas do quadrúpede com o solo durante a locomoção. Deste modo para uma configuração do modelo bem sucedida são tidos em conta limites geométricos e mecânicos. Por ultimo, o controlador com base no uso de ‘Central Pattern Generators’ foi melhorado a fim de se adaptar ao novo modelo e por conseguinte foram realizados testes simples usando o simulador WebotsTM. Nesta parte experimental é realizada a simulação do modelo permitindo avaliar o comportamento do modelo 3D para diferentes valores de coeficientes de mola e de amortecimento aplicados a nível do joelho da perna. Através de um algoritmo MATLAB® é possível caracterizar e analisar o comportamento doa ângulos das juntas durante a simulação

    Biomimetic leg design and passive dynamics of Dolomedes aquaticus

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    Spiders provide working models for agile, efficient miniature passive-dynamic robots. Joints are extended by haemoplymph (hydraulic) pressure and flexed by muscle-tendon systems. Muscle contraction in the prosoma leads to an increase in hydraulic pressure and subsequently leg extension. Analysis of body kinematics the New Zealand fishing spider, Dolomedes aquaticus indicates that elastic plates around the joints absorb energy from the ground reaction force when the force vector points backwards (i.e. would decelerate the spider’s body in the direction of locomotion) and release it to provide forward thrust as the leg swings backwards. In addition to improving energy efficiency, this mechanism improves stability by passively absorbing energy from unpredictable foot-ground impacts during locomotion on uneven terrain. These principles guided an iterative design methodology using a combination of 3D modelling software and 3D printing techniques. I compared and contrasted compliant joints made of a variety of plastic materials. The final 3D-printed spider leg prototype has a stiff ABS exoskeleton joined by a compliant polypropylene backbone. The entire structure envelopes a soft silicone pneumatic bladder. FEA analysis was used to determine the ideal shape and behavior of the pneumatic bladder to actuate the exoskeleton. The spider leg can be flexed and contracted depending on the input pressure. To laterally actuate this pneumatic spider leg I designed and developed a fabrication system that uses vacuum injection molding to produce an integrated mesh sleeve/elastomer pneumatic actuator. I designed an apparatus to measure pressure and contraction of silicone and latex pneumatic muscles when inflated. I analyzed the non-linear pressure-contraction relationships of silicone versus latex pneumatic muscles, and also derived force-contraction relationships. From efficiency studies, both media muscles proved to be inefficient and the measuring apparatus needs to be more robust to prevent leaking air. The fabrication process still offers the possibility of a quick and efficient method of creating pneumatic muscles. A spider-like robot that implements these pneumatic muscles and pneumatic leg design could be used to explore the efficiency and stability of passive dynamic legged locomotion in spider-like robots

    Wearable exoskeleton systems based-on pneumatic soft actuators and controlled by parallel processing

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    Human assistance innovation is essential in an increasingly aging society and one technology that may be applicable is exoskeletons. However, traditional rigid exoskeletons have many drawbacks. This research includes the design and implementation of upper-limb power assist and rehabilitation exoskeletons based on pneumatic soft actuators. A novel extensor-contractor pneumatic muscle has been designed and constructed. This new actuator has bidirectional action, allowing it to both extend and contract, as well as create force in both directions. A mathematical model has been developed for the new novel actuator which depicts the output force of the actuator. Another new design has been used to create a novel bending pneumatic muscle, based on an extending McKibben muscle and modelled mathematically according to its geometric parameters. This novel bending muscle design has been used to create two versions of power augmentation gloves. These exoskeletons are controlled by adaptive controllers using human intention. For finger rehabilitation a glove has been developed to bend the fingers (full bending) by using our novel bending muscles. Inspired by the zero position (straight fingers) problem for post-stroke patients, a new controllable stiffness bending actuator has been developed with a novel prototype. To control this new rehabilitation exoskeleton, online and offline controller systems have been designed for the hand exoskeleton and the results have been assessed experimentally. Another new design of variable stiffness actuator, which controls the bending segment, has been developed to create a new version of hand exoskeletons in order to achieve more rehabilitation movements in the same single glove. For Forearm rehabilitation, a rehabilitation exoskeleton has been developed for pronation and supination movements by using the novel extensor-contractor pneumatic muscle. For the Elbow rehabilitation an elbow rehabilitation exoskeleton was designed which relies on novel two-directional bending actuators with online and offline feedback controllers. Lastly for upper-limb joint is the wrist, we designed a novel all-directional bending actuator by using the moulding bladder to develop the wrist rehabilitation exoskeleton by a single all-directional bending muscle. Finally, a totally portable, power assistive and rehabilitative prototype has been developed using a parallel processing intelligent control chip
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