Browsing by Subject "Foldable robotics"

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Open Access
Collision resilient foldable micro aerial robot
(2019-09) Dilaveroğlu, Levent
Collision management strategies are integral part of micro air vehicles for the reliability of their operation. Collision avoidance strategies require enhanced environmental and situational awareness for generating evasive maneuver trajectories. Simpler and more adaptable option is to prepare for collisions and design the physical frame around predicted collision patterns. In this work, a mechanically compliant frame design collaborating origami-inspired foldable robotics methods with protective shock absorbing or guiding elements has been proposed for a collision resilient quad-rotor UAV. General workings and mathematical model of quadrotor has been explained to inform the reader further about the quadrotor mechanics. 2D design of the foldable structure and the manufacturing process, including electronic hardware elements and software has been discussed. Control scheme, communication and operation is explained in detail to be an informative guideline for the future air vehicle projects of the Bilkent Miniature Robotics Lab.
Open Access
Design, control, modeling, and locomotion analysis of a multi-legged modular miniature robot with soft backbones
(2020-07) Mahkam, Nima
Soft 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.
Open Access
Design, manufacturing, and rough terrain analysis of a collision resilient foldable, adjustable wheeled miniature robot: FAWSCY
(2021-01) Demir, Didem Fatma
FAWSCY: 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.