825 research outputs found

    Flexible couplings: diffusing neuromodulators and adaptive robotics

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    Recent years have seen the discovery of freely diffusing gaseous neurotransmitters, such as nitric oxide (NO), in biological nervous systems. A type of artificial neural network (ANN) inspired by such gaseous signaling, the GasNet, has previously been shown to be more evolvable than traditional ANNs when used as an artificial nervous system in an evolutionary robotics setting, where evolvability means consistent speed to very good solutionsÂżhere, appropriate sensorimotor behavior-generating systems. We present two new versions of the GasNet, which take further inspiration from the properties of neuronal gaseous signaling. The plexus model is inspired by the extraordinary NO-producing cortical plexus structure of neural fibers and the properties of the diffusing NO signal it generates. The receptor model is inspired by the mediating action of neurotransmitter receptors. Both models are shown to significantly further improve evolvability. We describe a series of analyses suggesting that the reasons for the increase in evolvability are related to the flexible loose coupling of distinct signaling mechanisms, one ÂżchemicalÂż and one Âżelectrical.

    Steerable miniature jumping robot

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    Jumping is used in nature by many small animals to locomote in cluttered environments or in rough terrain. It offers small systems the benefit of overcoming relatively large obstacles at a low energetic cost. In order to be able to perform repetitive jumps in a given direction, it is important to be able to upright after landing, steer and jump again. In this article, we review and evaluate the uprighting and steering principles of existing jumping robots and present a novel spherical robot with a mass of 14g and a size of 18cm that can jump up to 62cm at a take-off angle of 75°, recover passively after landing, orient itself, and jump again. We describe its design details and fabrication methods, characterize its jumping performance, and demonstrate the remote controlled prototype repetitively moving over an obstacle course where it has to climb stairs and go through a window. (See videos 1-4 in the electronic supplementary material.

    The EPFL jumpglider: A hybrid jumping and gliding robot with rigid or folding wings

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    Recent work suggests that wings can be used to prolong the jumps of miniature jumping robots. However, no functional miniature jumping robot has been presented so far that can successfully apply this hybrid locomotion principle. In this publication, we present the development and characterization of the ’EPFL jumpglider’, a miniature robot that can prolong its jumps using steered hybrid jumping and gliding locomotion over varied terrain. For example, it can safely descend from elevated positions such as stairs and buildings and propagate on ground with small jumps. The publication presents a systematic evaluation of three biologically inspired wing folding mechanisms and a rigid wing design. Based on this evaluation, two wing designs are implemented and compared

    Exploration of an electroactive polymer actuator for application in a grasshopper inspired pneumatic robotic hopper

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    A Hopper was created to mimic a grasshopper\u27s catapulting kicking action. Electroactive polymers (EAP) were investigated as actuators to simulate the grasshopper\u27s lightweight and strong muscles. EAPs are lightweight materials that require low voltage and yield high force with short response times. This makes them a great potential source for future micro-robotic actuators. The EAP Actuator was simulated and the potential design was studied. The development of consistent and reliable actuation electrodes and nonconductive materials was considered. In addition, the current draw of the EAP Actuator was studied, current draw prediction equations were developed, and a force output study was conducted. Finally, the EAP Actuators were compared to other conventional actuators, including pneumatic actuators, for performance and weight requirements. The EAP Actuator will ultimately be a reliable and powerful actuator for un-tethered, lightweight robotic hoppers. The Hopper was simulated, built, and tested using pneumatic actuators. Each Hopper contained four actuators. The actuators\u27 contraction and release were controlled by a Parallax Basic Stamp II microcontroller and 4 relays. A 9-volt battery, a 0-20 volt variable off board power supply, and a 60 psi off-board compressed air supply were required for operation. The Pneumatic Hopper results were compared to the EAP Hopper\u27s analytical results. For both the Pneumatic and EAP Hoppers, the motion was modeled in Working Model Software. These computer-generated results were compared using Lumped Mass Equations in MatLab and Two Segmented Leg Robotic Hopper Equations presented by R. M. Alexander. The Pneumatic Hopper was then tested for performance. It ultimately yielded a hop height of 2.4 mm and an average hop range of 12.7 mm

    Evolving controllers for robots with multimodal locomotion

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    Animals have inspired numerous studies on robot locomotion, but the problem of how autonomous robots can learn to take advantage of multimodal locomotion remains largely unexplored. In this paper, we study how a robot with two different means of locomotion can effective learn when to use each one based only on the limited information it can obtain through its onboard sensors. We conduct a series of simulation-based experiments using a task where a wheeled robot capable of jumping has to navigate to a target destination as quickly as possible in environments containing obstacles. We apply evolutionary techniques to synthesize neural controllers for the robot, and we analyze the evolved behaviors. The results show that the robot succeeds in learning when to drive and when to jump. The results also show that, compared with unimodal locomotion, multimodal locomotion allows for simpler and higher performing behaviors to evolve.info:eu-repo/semantics/acceptedVersio

    An Overview of Legged Robots

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    The objective of this paper is to present the evolution and the state-of-theart in the area of legged locomotion systems. In a first phase different possibilities for mobile robots are discussed, namely the case of artificial legged locomotion systems, while emphasizing their advantages and limitations. In a second phase an historical overview of the evolution of these systems is presented, bearing in mind several particular cases often considered as milestones on the technological and scientific progress. After this historical timeline, some of the present day systems are examined and their performance is analyzed. In a third phase are pointed out the major areas for research and development that are presently being followed in the construction of legged robots. Finally, some of the problems still unsolved, that remain defying robotics research, are also addressed.N/

    OPTIC FLOW BASED STATION-KEEPING AND WIND REJECTION FOR SMALL FLYING VEHICLES

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    Optic flow and Wide Field Integration (WFI) have shown potential for application to autonomous navigation of Unmanned Air Vehicles (UAVs). In this study the application of these same methods to other tasks, namely station-keeping and wind rejection, is examined. Theory surrounding optic flow, WFI and wind gust modeling is examined to provide a theoretical background. A controller based on a H∞ bounded formulation of the well known Linear Quadratic Regulator in designed to both mitigate wind disturbances and station-keep. The performance of this controller is assessed via simulation to determine both performance and trade-offs in implementation such as the method for optic flow calculation. Furthermore, flight tests are performed to examine the real world effectiveness of the controller. Finally, conclusions about potential improvement to implementation are drawn
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