Browsing by Subject "Soft robot materials and design"

Now showing 1 - 8 of 8

Open Access
Design, fabrication, and locomotion analysis of an untethered miniature soft quadruped, SQuad
(IEEE, 2020) Kalın, Mert Ali İhsan; Aygül, Cem; Türkmen, Altay; Kwiczak-Yiğitbaşı, Joanna; Baytekin, Bilge; Özcan, Onur
The conventional robotics, which involves utilization of robots made out of hard materials like metals and hard plastics, has helped humankind automate many different sorts of labor and such robots have been assisting the humans in various tasks. Nevertheless, some applications require very delicate interactions and adaptability of the robots to unstructured elements and obstacles; which can only be provided by softness. The miniature and untethered robot in this work is fully made out of soft structural materials and uses a flexible circuit board. Only the electronic components, actuators and several little connection parts are hard. Its soft legs, body, and circuit enables it to overcome obstacles that conventional hard miniature robots tend to be stopped by. For the soft robot presented, walking and obstacle climbing experiments were done and pitch angle, roll angle, robot's centroid position and stiffness analyses were conducted. Additionally, three other robots are fabricated in hard body - hard leg, hard body - soft leg, and soft body - hard leg configurations and the effects of body and leg compliance on the locomotion performance are investigated. The results show that a soft body - soft leg robot configuration can scale an obstacle 1.44 times its body height whereas the hard bodied and hard legged robot can only go over 0.88 times its body height. The results also indicate that the softness of the body effects the scalable obstacle height more than the softness of the legs at this length scale.
Open Access
Detecting scalable obstacles using soft sensors in the body of a compliant quadruped
(Institute of Electrical and Electronics Engineers, 2022-01-10) Özbek, Doğa; Yılmaz, Talip Batuhan; Kalın, Mert Ali İhsan; Şentürk, Kutay; Özcan, Onur
In soft robotics, one of the trending topics is using soft sensors to have feedback from the robot's body. This is not an easy process to accomplish since the sensors are often nonlinear, so researchers use different methods to generate information from data such as filters, machine learning algorithms, and optimization algorithms. In this paper, we show that, with good electronic and mechanical design, it is possible to use soft sensors for detecting obstacles and distinguishing the scalable obstacles. The demonstration is conducted with an untethered miniature, soft, C-legged robot, M–SQuad, the first modular C-legged quadruped consisting of three modules, which are connected by four soft sensors. In M–SQuad's body design, sensors are utilized as both sensing and structural elements. The modular design of the M–SQuad allows testing different sensor geometries and replacing the malfunctioning parts easily, without the need to refabricate the entire robot. A case study is introduced for demonstration of the robot's capability of detecting obstacles and distinguishing scalable obstacles in a parkour consisting of two obstacles with the heights of 20 mm and 150 mm, respectively. In the case study, M–SQuad can detect an obstacle during locomotion using the coil-spring shaped soft sensors in its body. Moreover, it can distinguish the obstacle is scalable or not after an initial climbing trial. If the obstacle is not scalable, the robot turns back.
Open Access
Effect of feet failure and control uncertainties on the locomotion of multi-legged miniature robots
(Institute of Electrical and Electronics Engineers, 2022-03-09) Mahkam, Nima; Uğur, Mustafa; Özcan, Onur
This study investigates the effects of control uncertainties and random feet failures on the locomotion of the multi-legged miniature robots. The locomotion analyses results are verified with our modular multi-legged miniature robot with a soft/hybrid body named SMoLBot. A single SMoLBot module is 44.5 mm wide, 16.75 mm long, and 15 mm high with two individually actuated and controlled DC motors. This individual actuation makes it feasible to run with any imaginable gait, making SMoLBot a nice candidate for gait study analyses. The presented locomotion study shows that the effects of control uncertainties and feet failures are highly dependent on the total number of legs and the type of backbone attached to the robot, e.g., increasing the total number of legs or utilizing a rigid backbone on the robot helps the robot to walk faster compared to similar robots with soft backbones or the ones with fewer modules. This study presents a guide to the researchers on the effects of feet failures and control uncertainties on the locomotion of soft/hybrid multi-legged miniature robots.
Open Access
Joint design and fabrication for multi-material soft/hybrid robots
(IEEE, 2019-04) Aygül, Cern; Kwiczak-Yiğitbaşı, Joanna; Baytekin, Bilge; Özcan, Onur
The 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.
Open Access
Miniature modular legged robot with compliant backbones
(IEEE, 2020) Mahkam, Nima; Bakır, Alihan; Özcan, Onur
Soft Modular Legged Robot (SMoLBot) is a miniature, foldable, modular, soft-hybrid legged robot with compliant 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 out of PDMS. Each single module in SMoLBot is actuated and controlled by two separate DC motors. This enables gait modification and 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 with two DC motors and a LiPo battery. The comparisons between robots with compliant and rigid backbones demonstrate smoother walking pattern, and approximate decrease in body's roll angle from 12° to 6°, and pitch from 10° to 7°. The independent actuation and control over each leg in n number of modules make SMoLBot an ideal candidate for gait studies. Moreover, the possibility of changing the structural stiffness of the robot with different backbones enables such a compliant modular robot to be used for locomotion optimization studies in miniature scale.
Open Access
MiniCoRe: A miniature, foldable, collision resilient quadcopter
(IEEE, 2020) Dilaveroğlu, Levent; Özcan, Onur
Collision 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.
Open Access
SCoReR: sensorized collision resilient aerial robot
(IEEE - Institute of Electrical and Electronics Engineers, 2023-05-15) Bakır, Alihan; Özbek, Doğa; Abazari, Amirali; Özcan, Onur
Detection and control of the physical contact/impact between micro aerial vehicles and the surrounding obstacles have become a significant issue with the rapid growth of their use in inspection and mapping missions in confined, obstacle-cluttered environments. In this work, we introduce a collision-resilient compliant micro quadcopter equipped with soft coil-spring type force sensors to passively resist and detect the physical contact/impact of the drone. The sensors act as resistive elements with a nominal resistance of 130–150 kΩ. They are manufactured from a conductive material via FDM 3D printing. We install these sensors on the protective bumpers of the collision-resilient foldable body of the drone. Any contact/impact between the bumpers and an obstacle results in deformation and buckling of the soft sensors, which results in a drastic change in their resistance, making it possible to detect the contacts/impacts of the bumpers. With a total weight of 220g and dimensions of 22cmx22cmx9cm, SCoReR successfully detects and recovers 100% of the contacts/impacts when it approaches a rigid wall with a velocity in the range of [0.1-1] m/s.
Open Access
Smooth and inclined surface locomotion and obstacle scaling of a C-legged miniature modular robot
(IEEE, 2021-07-12) Mahkam, Nima; Yılmaz, Talip Batuhan; Özcan, Onur
This work investigates the locomotion of a modular C-legged miniature robot with soft or rigid backbones on smooth, rough, and inclined terrain. SMoLBot-C is a C-legged miniature robot with soft or rigid backbones and foldable modules. The robot's climbing capabilities with soft and rigid C-legs and different backbones on rough terrain with obstacles and the robot's mobility on an inclined surface are compared. Our results show that the C-legged robot with soft legs and soft backbones can climb up to a higher obstacle, and walk on surfaces with higher inclination angles compared to the same robot with rigid legs and backbones, regardless of the number of modules (legs). Additionally, a velocity comparison study using SMoLBot-C operating at two different gaits is conducted. The results show that the robot with soft legs and compliant-I backbones operating with trot gait possesses the highest velocity compared to the other robots with similar leg numbers. Moreover, the effect of a compliant tail on the robot's locomotion on smooth and rough terrains is investigated, where the results show that the robot with the compliant tail is capable of walking on surfaces with higher inclination angles compared to the same robot without a tail. Furthermore, adding a tail to the two-legged SMoLBot-C doubles the maximum scalable obstacle height; the robot with a tail can climb up an obstacle 2 times higher than a module's height. Locomotion analysis in this manuscript provides a better insight into C-legged miniature robots' locomotion with soft or rigid legs while the modular connections' structural stiffness varies from rigid to soft.