Browsing by Subject "Soft robots"
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Item Open Access Joint design and fabrication for multi-material soft/hybrid robots(IEEE, 2019-04) Aygül, Cern; Kwiczak-Yiğitbaşı, Joanna; Baytekin, Bilge; Özcan, OnurThe premises of safer interactions with surroundings and the higher adaptability to its environment make soft robotics a very interesting research field. Some robots try to achieve these feats using soft materials in their designs whereas some achieve behavioral softness through compliant use of hard materials. In this work, we present soft/hybrid robot leg designs that utilize elastomers as leg materials but hard DC motors as actuators. Two different leg designs that would convert the rotational motion of the DC motors to a foot trajectory are proposed. The different leg designs are kinematically identical; however, the hourglass design utilizes geometrical modifications to differentiate joint locations, whereas the composite design uses materials with different Young's Moduli without geometrical effects to create joints. In order to fabricate the composite design, a new method is developed involving 3D printed molds with removable joint pieces and a two-step molding process. Both of the legs are fabricated and simulations and experiments are run to compare their performances. Both mechanisms achieve a good foot trajectory, however the hourglass joint experiences higher mechanical stress during operation, which might lead to earlier failure especially under high loads. Such multi-material structures made out of elastomers can be utilized in miniature robots or mechanisms of similar size in which absolute joint locations are needed and continuum robotic limbs are not preferred.Item Open Access MiniCoRe: A miniature, foldable, collision resilient quadcopter(IEEE, 2020) Dilaveroğlu, Levent; Özcan, OnurCollision management strategies are an integral part of micro air vehicle (MAV) operation for flight sustainability. Among them, collision avoidance strategies require enhanced environmental and situational awareness for generating evasive maneuvers and collision-free trajectories. Simpler and more adaptable option is to prepare for collisions and design the physical system with predicted collision patterns in mind. In this work, a mechanically compliant quadcopter design using origami-inspired foldable robotics methods with protective shock absorbing elements has been proposed for a collision resilient quad-rotor MAV. 2D design of the foldable structure and the manufacturing process, including electronic hardware elements and software has been discussed. Our results show that in low speed collisions, the flight of the quadcopter is uninterrupted. The compliant quadcopter can continue flight after impact in near-hover conditions because of the reduction of impact forces due to the increased impact time.Item Open Access ReMBot: A reconfigurable, miniature, modular robot with soft connection mechanisms(Bilkent University, 2023-07) Uğur, MustafaNature has been a valuable source of inspiration for engineers, leading to the development of diverse materials, mechanisms, and algorithms that have enhanced human life. One fascinating idea borrowed from nature is the collaborative work of ant colonies. Ants work together to accomplish tasks that are impossible to achieve individually, such as constructing bridges by connecting to one another. Researchers have been motivated by such examples to create reconfigurable robots that can perform various exciting tasks, such as climbing stairs, crossing gaps, moving objects, and assisting in furniture building, by moving as separate modules and docking to each other using different connection mechanisms. However, the connection mechanism remains a challenge. Many of the existing designs re-quire an actuator or a driving circuit which makes the control harder and limits the robot’s motion. This thesis presents ReMBot: A self-reconfigurable, miniature, modular robot with a soft connection mechanism. The robot comprises multiple modules, each equipped with backbones featuring permanent magnets. Using permanent magnets offers reconfigurability without requiring additional power, actuation, or a driving circuit while enhancing the robot’s compliance. The modules, including the body, electronics, actuators, c-shaped soft legs, and backbones with magnets, weigh 29.43 grams and have 82 mm x 60 mm x 14.7 mm dimensions. These module specifications, combined with the whole system design, allow ReMBot modules to execute path-tracking tasks, dock and undock, and sense the connection between modules. Their ability to connect and maintain a longer structure enables the ReMBot to climb obstacles higher than itself. Soft c-shaped legs enable modules to dock successfully by ensuring successful path-tracking tasks while they help them to move in different terrains like gravel, sand, or grass. The modules’ miniature structure, ease of manufacture, and affordability make them a suitable option for multiple use cases. The robot’s wireless communication capability makes it a strong contender for surveillance in confined spaces like collapsed buildings and nuclear sites, large areas like farmlands, and even planetary exploration missions.Item Open Access Theoretical and experimental analysis of a soft and miniature quadruped(Bilkent University, 2020-11) Taşkıran, TamerMulti-body dynamic modeling of non-rigid and legged robots is an active research area with the goal of investigating the interaction of a robot with its environment and its resulting locomotion. The results of such studies can be used to build a simulation that will be used for the iterative process of the mechanical design of the robot, and the algorithm design of its high- and low-level controllers. The dynamics of soft robots is more challenging comparing to rigid robots because of the partial derivatives and the shape integrals existing in the dynamic models, and the literature is open to improvement. The subject of this study is S-Quad, a soft and miniature quadruped with c-shaped legs. To analyze the effect of the compliance of its body and legs to its locomotion, a soft-body dynamic model has been developed. The development process starts with the rigid-body dynamic analysis, which will be a base for the soft-body dynamic analysis and used to examine the rigid body - rigid legs (RBRL) version of the robot. The Newton-Euler method has been used to develop this model, in which the contact forces are estimated with the viscoelasticity theory. Scenarios of different model parameters were simulated to estimate the motion of the robot. With the obtained results the effects of the model parameters were discussed, and then appropriate parameters have been selected. The contact analysis of a curved leg inside of the robot dynamics, in which any intersection algorithm is not used, is an advantageous aspect of this study. The compliance of the legs has been incorporated into this dynamic analysis with a non-linear viscoelastic model. The dependency of the leg compliance to the roll angle of the leg was derived from Castigliano’s theorem. Then, the motion of the rigid body - soft leg (RBSL) robot was estimated accordingly. The comparison of the RBRL and the RBSL results was utilized to interpret the effect of the leg compliance. The modeling and the integration with robot dynamics of this compliant leg model is a novel aspect of this model. An offline Finite Element Analysis has been conducted to estimate the deflections of the soft body under the contact forces, which were exported from the RBRL simulation. The estimated deflections were put back into this simulation to obtain the simulation of soft body - rigid legs (SBRL) robot. Thus, the capability of the developed model to include body deflections has been proven. Finally, the RBRL and the RBSL robot simulations have been verified with the experiments conducted with a motion capture system. These experimental results were also used to interpret the advantages and disadvantages of using a soft body in the robot.