Browsing by Subject "Miniature robotics"
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Item Open Access Design, characterization, and applications of soft 3D printed strain gauges(Bilkent University, 2023-07) Özbek, DoğaThe development of soft sensors for integration into untethered miniature robots is significant for improving their environmental perception in physically challenging scenarios, such as collapsed buildings after an earthquake. The primary objective is to design and manufacture reliable soft sensors that serve as structural and sensing elements within the robots, eliminating the need for post-processing methods like data-driven learning and optimization. The soft sensors employ resistive sensing, similar to strain gauges, and are implemented on a Wheatstone bridge to convert resistive changes into voltage changes under me-chanical actuation or deformation. The study explores two categories of soft sensor designs: sheet-type and 3D shaped sensors. Sheet-type sensors are embedded in the C-legs of a soft quadruped robot (SQuad), enabling gait control, while 3D shaped sensors are structurally integrated into the robots to enhance environmental perception. Manufacturing of the soft sensors is made accessible and efficient through 3D printing technology, using conductive Thermoplastic Polyurethane (cTPU) as the printing material. Challenges arise in integrating the soft sensors into the robots while preserving their soft nature, locomotion, and agility. The thesis addresses these challenges by implementing the soft sensor concept in various robots and their parts, including the C-leg of SQuad, Modular Soft Quadruped (M-SQuad), Suspensionized Soft Quadruped (S-SQuad), Sensorized Collision Resilient Robot (SCoReR), and a tail for Reconfigurable Miniature Modular Robot (ReMBot). The soft sensors enable different functionalities to these robots, such as gait control feedback, obstacle detection, inclination detection, and collision detection, enhancing the adaptability of the robots in physically challenging environments. The thesis highlights the potential of soft 3D printed strain gauges. The ease of manufacturing and cost-efficiency of these sensors make them promising for applications in wearable robots and human-computer interfaces. Future directions are highlighted, emphasizing the need for detailed sensor characterization experiments and the development of detection algorithms to improve reliability. Additionally, a dynamic model of the coil-shaped sensors is proposed to simulate resistance changes, streamlining the design process without repetitive manufacturing iterations. As a result, this thesis presents a reliable soft sensor design, manufacturing, and integration into untethered miniature robots. The outcome of this work demonstrates the effectiveness of soft sensors in enhancing environmental perception, paving the way for innovative solutions in force measurement applications and human-computer interactions.Item Open Access Design, control, fabrication and maneuverability analysis of an untethered miniature soft robot(Bilkent University, 2019-09) Aygül, CemAs the robotics field grows, it searches for new potential workspaces to be interacting with. The conventional robotics, which involves utilization of robots made out of hard materials like metals and hard plastics, has helped humankind automatebmany different sorts of labor and such robots have been assisting the humans in various tasks. Nevertheless, some environments require very delicate interactions and adaptability of the robots to unstable elements and obstacles. A fairly new sub-field of robotics, soft robotics, arises as a very alluring area of research as it promises advancements in these particular premises beyond the conventional hard robotics. A major point of dispute arises around the term 'softness' as some specific robots achieve softness via the use of soft materials (specific polymers like PDMS) whereas although some others are made out of hard materials, they behave in a soft manner thanks to clever use of the mechanisms involved in them. The robot in this work is fully made out of soft structural materials and uses a exible circuit board. The electronics, actuators and several little connection parts are hard. The robot that is designed and constructed is a soft-hybrid robot that can be considered as a preliminary standpoint for autonomous robots to be operating in challenging working environments such as earthquake zones, pipelines, rough terrain military areas and so on. Miniature sized, it can be fitted with various sensors and communication devices in order to be used for search and rescue, surveillance and patrol missions. Its soft legs, body, and circuit enables it to overcome obstacles that conventional hard miniature robots tend to be tackled by The work I did involves mostly iterative sequences due to the challenges of modeling the soft components' behavior. Different leg mechanisms with different types of actuators are evaluated. Some of the evaluated mechanisms utilize a kinematic chain whereas the final version does not. These can be considered the novel aspects of the work done as virtually no examples in the literature use kinematic chains in soft robots. Thus, my work can be considered to be a multi-disciplinary study that involves design and fabrication of different soft locomotion mechanisms, body designs, and exible circuit boards. Finite element analyses are conducted in order to estimate differences between different leg mechanisms and soft joints. Finally, by the help of specific sensors and microcontrolling elements, the whole robot is controlled to maneuver in the desired behavior.Item Open Access Design, control, modeling, and locomotion analysis of a multi-legged modular miniature robot with soft backbones(Bilkent University, 2020-07) Mahkam, NimaSoft Modular Legged roBot (SMoLBot) is a legged, foldable, modular, miniature robot with soft backbones. SMoLBot’s body and locomotion mechanisms are folded out of acetate sheets and its compliant connection mechanisms are molded from Polydimethylsiloxane (PDMS). High maneuverability and smooth walking pattern can be achieved in miniature robots if high stiffness kinematic parts are connected with compliant components, providing the robot structural compliance and better adaptability to different surfaces. SMoLBot is exploiting features from origami-inspired robots and soft robots, such as low weight and low cost foldable rigid structures and adaptable soft connection mechanisms made of PDMS. Every single module in SMoLBot is actuated and controlled by two separate DC motors, that enable gait modification and a higher degree of freedom on controlling the motion and body undulation of the robot in turning and rough terrain locomotion. Each module has 44.5 mm width, 16.75 mm length, and 15 mm height, which is approximately the same size as two DC motors and a Li-Po battery. The dynamic formulation of SMoLBot is obtained using Newton-Euler formulation and it depends on the physical parameters of the contact and closed-chain kinematic analysis of the feet. The dynamic model framework is proposed by determining the dynamic locomotion parameters of each module as an individual system, as well as, considering the dynamics of the whole robot; i.e. the robot is modeled as one system and modules are considered to be set of flexible links connected to each other, within this system. Kinematic constraints among these modules are obtained by considering the types of backbones integrated in the robot. Various types of backbones are used within the experiments that are classified into two groups: rigid, and compliant backbones. Experimental results of SMoLBot running/walking with different symmetrical and asymmetrical gates validate the dynamic model presented in this thesis. Additional to the dynamic model, the effect of the backbone stiffness on the locomotion of the legged miniature modular robots with multiple numbers of modules is studied. Analyses comparing the velocity of SMoLBot with different numbers of modules and different types of backbones are presented using the proposed dynamic model. The results indicate that there is an optimum torsional stiffness of the backbone for a legged miniature modular robot that maximizes the robot’s translational velocity. Additionally, we can show that, for a given backbone stiffness or a specific range of compliance between the modules, there is an optimum number of feet for the miniature robots. Furthermore, in this thesis, a locomotion study that investigates the motion patterns of the running/walking multi-legged modular miniature robots with soft module connections, is conducted. The locomotion study is done using the presented dynamic model and results are verified using SMoLBot. The optimum feet sequence and the optimum stride length of a multi-legged robot are derived using the locomotion analyses, and the dynamic and kinematic formulations. The optimum gait analysis of the multi-legged SMoLBots represents different but unique feet contact sequence patterns for each robot with a different module number and diverse ranges of compliance between the modules. Furthermore, analysis considering the effect of various feet failure cases on the locomotion of a multilegged robot with soft/rigid backbones, is conducted. This study investigates the locomotion behavior of a legged miniature robot with different combinations of the non-functioning feet. Additionally, a case-sensitivity study of an n-legged SMoLBot’s locomotion on its individual modules during the operation, is also conducted. This study investigates the modular robot’s locomotion with multiple different failure cases where each particular case only considers the effect of an individual module failure on the overall motion of the robot, while the gate is not altered.Item Open Access Design, fabrication, and locomotion analysis of an untethered, miniature, legged, compressible, soft robot: CSQUAD(Bilkent University, 2021-09) Kalın, Mert Ali İhsanConventional robotics has been effective for industrial applications such as fast, precise and accurate production or for sophisticatedly controlled systems for the last couple of centuries. However, as the robots become more ubiquitous in every-day lives of people, the drawbacks of conventional and rigid robots have become more and more apparent. One of the biggest problems that soft robots solve is the safe interactions with humans. Whether it be a minimally invasive surgery or a search and rescue operation under rubble, the soft robots offer better performance especially in terms of compliance compared to their rigid counterparts. With especially the search and rescue environments in mind, this study presents an untethered, miniature, legged and compressible soft quadruped (cSQuad). This robot is equipped with C-shaped legs for better locomotion per-formance on unstructured surfaces. It is made out of soft materials, mainly from polydimethylsiloxane (PDMS), it utilizes a flexible printed circuit board (PCB) and only some small sensors, actuators and electronic components are made out of rigid materials. The main goal of this robot is to have the ability to pass through openings that are smaller than its cross-section. In order to achieve this goal, the robot is designed to be compressible. Both the body of the robot and its C-shaped legs can compress themselves using shape memory alloy (SMA) springs. The design and fabrication steps of cSQuad is explained in detail and the tests have been done to verify that the robot can reduce its cross-section area by at least 25%. cSQuad is the successor of SQuad which is also a soft quadruped with C-shaped legs. Before starting the design of cSQuad, the locomotion performance of SQuad was studied to make sure that it would be worth continuing to design new generation of soft quadrupeds. This study was a comparative study between the soft quadruped (SQuad) and its rigid and hybrid twins. The study consisted of speed, pitch and roll angle, body centroid position and obstacle climbing per-formance analysis. The results of this analyses showed that even though the soft robot was slower it gave better performance in terms of obstacle climbing and smooth locomotion. This gave us the confidence to continue improving the robot which resulted in designing of cSQuad. SMA springs of cSQuad are placed on specifically calculated locations on the body and the legs of the robot to achieve optimum compression performance. To transmit power to the SMAs on continuously rotating legs, a custom slip-ring device was built utilizing pogo pins. The compression tests for the legs and the body were conducted separately. Then, a robot with both leg and body compression was built and tested. As a result, a robot with the capability of reducing its cross-section area by at least 25% is built and tested. This robot can be used as a base design for the new generation of robots that could be used in search and rescue operations. It has the potential to be equipped with specific sensors for specific tasks. The fabrication and design steps can also be considered as a framework for fabricating soft robots in general.Item Open Access Design, manufacturing, and rough terrain analysis of a collision resilient foldable, adjustable wheeled miniature robot: FAWSCY(Bilkent University, 2021-01) Demir, Didem FatmaFAWSCY: Foldable Adjustable Wheeled Stringy Clumsy Robot is a foldable, collision resilient, adjustable wheeled robot which can run through different ter-rains and inclined surfaces, to inspect areas which are unavailable to humans due to dimensional limitations or hazardousness level; to attend search and rescue missions to cover more area in a shorter duration and to be a part of somatic activities with elders and kids. Hence, it is desired to be non-harmful to itself and its environment in case of any collisions or falls, and persistent on its run under various conditions and terrains as any insect or lizard can. FAWSCY is an incremental work that till attaining its final version, several legs and wheels; and electronic components and their combinations are investi-gated. First, c-legs are tested due to its advantages on rough terrains, yet they lack sensor implementation by its constant oscillatory movement. Then ninja stars are tested the robot yet they are so rigid that they sunder from the body in presence of a collision or undesired tracking. Afterwards, the bellow design is modified to be enforced as a wheel and it is the most promising wheel configu-ration since it can damp all longitudinal, lateral and vertical forces during the impact of a collision and fall. Also, it has appreciable rough terrain performance. However, as well as being soft it is also quite strong that it cannot be controlled for different length configurations for a miniature untethered scale. Therefore, it is not applicable for FAWSCY. On its final adjustable wheel, a novel wicker modular wheel design which exhibits similar behaviour with the bellow design, and its adjusting mechanism are proposed. On the other hand, Raspberry Pi is chosen to be the main processor, and by experiments and investigation through different motors, sensors and control strategies, a two part single board design is finalized. The body of FAWSCY is also kirigami-inspired and formed by foldable sheets to cover and maintain integrity of its parts and components. After the design is completed, its performance and capabilities are assessed. First, its indoor run performance, wheel adjustment mechanism, collision resilient properties, obstacle scaling and response to inclination are investigated. The robot is assessed to be suitable for indoor environments, stairs and inclinations without getting disintegrated and harming other living subjects. Then, rough terrain experiments are conducted which resulted in success on grass, gravel and soil terrains with diverse wheel length configurations.