Browsing by Subject "Bio-inspired systems"

Now showing 1 - 2 of 2

Open Access
Design, characterization, and applications of soft 3D printed strain gauges
(2023-07) Özbek, Doğa
The 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.
Open Access
Design, fabrication, and locomotion analysis of an untethered, miniature, legged, compressible, soft robot: CSQUAD
(2021-09) Kalın, Mert Ali İhsan
Conventional 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.