178 research outputs found

    Incorporating prior knowledge into deep neural network controllers of legged robots

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    A literature review on the optimization of legged robots

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    Over the last two decades the research and development of legged locomotion robots has grown steadily. Legged systems present major advantages when compared with ‘traditional’ vehicles, because they allow locomotion in inaccessible terrain to vehicles with wheels and tracks. However, the robustness of legged robots, and especially their energy consumption, among other aspects, still lag behind mechanisms that use wheels and tracks. Therefore, in the present state of development, there are several aspects that need to be improved and optimized. Keeping these ideas in mind, this paper presents the review of the literature of different methods adopted for the optimization of the structure and locomotion gaits of walking robots. Among the distinct possible strategies often used for these tasks are referred approaches such as the mimicking of biological animals, the use of evolutionary schemes to find the optimal parameters and structures, the adoption of sound mechanical design rules, and the optimization of power-based indexes

    On the Biomimetic Design of Agile-Robot Legs

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    The development of functional legged robots has encountered its limits in human-made actuation technology. This paper describes research on the biomimetic design of legs for agile quadrupeds. A biomimetic leg concept that extracts key principles from horse legs which are responsible for the agile and powerful locomotion of these animals is presented. The proposed biomimetic leg model defines the effective leg length, leg kinematics, limb mass distribution, actuator power, and elastic energy recovery as determinants of agile locomotion, and values for these five key elements are given. The transfer of the extracted principles to technological instantiations is analyzed in detail, considering the availability of current materials, structures and actuators. A real leg prototype has been developed following the biomimetic leg concept proposed. The actuation system is based on the hybrid use of series elasticity and magneto-rheological dampers which provides variable compliance for natural motion. From the experimental evaluation of this prototype, conclusions on the current technological barriers to achieve real functional legged robots to walk dynamically in agile locomotion are presented

    Kinematic Design and Optimisation of a Quadruped Robot with Six Actuated DoF

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    While legged robots hold many advantages over wheeled robots, especially regarding dynamic capabilities and mobility, they often suffer from lower energy efficiency and reliability due to the use of more actuators. Many classic approaches to quadruped design rely on designs with 12 actuated degrees of freedom - three in each leg - which allows the feet to be freely placed with respect to the body. One obvious solution to this problem is a reduction in the number of actuators, but this usually comes at the cost of functionality reduction. In terms of simple locomotion, however, the robot’s center of mass can be sufficiently moved by freely placing each foot with respect to the world, thus changing the robot’s contact points. It should then be possible to achieve locomotion with free foot placement using only six actuated degrees of freedom if the existing functions are appropriately combined and/or reduced. The aim of this thesis is therefore to design a full quadruped kinematic structure with only six actuators which is capable of simple locomotion through free placement of its feet. A review of existing literature regarding legged locomotion and reduced-DoF quadrupeds is performed to form a basis for new concepts, and a novel kinematic structure is proposed which relies on two types of leg couplings to reduce the degrees of freedom. A kinematic analysis then provides representations of the model in terms of forward, inverse and differential kinematics, and a control algorithm with position error feedback is proposed for task-space trajectory following. The proposed model is implemented in Creo Parametric and simulated with the help of the LucaDynamics library in MATLAB. A few tests are performed in the simulated environment which show that the proposed robot is indeed capable of stable static walking with free placement of all four feet, with the task-space position errors remaining very low for all tested trajectories and no indications of singular or near-singular poses

    Locomation strategies for amphibious robots-a review

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    In the past two decades, unmanned amphibious robots have proven the most promising and efficient systems ranging from scientific, military, and commercial applications. The applications like monitoring, surveillance, reconnaissance, and military combat operations require platforms to maneuver on challenging, complex, rugged terrains and diverse environments. The recent technological advancements and development in aquatic robotics and mobile robotics have facilitated a more agile, robust, and efficient amphibious robots maneuvering in multiple environments and various terrain profiles. Amphibious robot locomotion inspired by nature, such as amphibians, offers augmented flexibility, improved adaptability, and higher mobility over terrestrial, aquatic, and aerial mediums. In this review, amphibious robots' locomotion mechanism designed and developed previously are consolidated, systematically The review also analyzes the literature on amphibious robot highlighting the limitations, open research areas, recent key development in this research field. Further development and contributions to amphibious robot locomotion, actuation, and control can be utilized to perform specific missions in sophisticated environments, where tasks are unsafe or hardly feasible for the divers or traditional aquatic and terrestrial robots
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