Browsing by Subject "Modular robots"

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Open Access
A framework for dynamic modeling of legged modular miniature robots with soft backbones
(Elsevier, 2021-06-29) Mahkam, Nima; Özcan, Onur
In this work, the dynamics of ”n” legged modular miniature robots with a soft body is modeled. The dynamic formulation is obtained using Newton–Euler formulation that depends on the contact parameters and the feet closed-chain kinematic analysis. The dynamic model determines the locomotion parameters of each module as an individual system as well as the dynamics of the whole robot in a 3D space; i.e., the robot is modeled as one system, and modules are considered to be sets of flexible links connected within this system. Kinematic constraints among these modules are obtained by considering the type of backbone integrated into the modular robot. Various types of backbones are used that are classified into three groups: rigid, only torsional, and soft. The model is verified using SMoLBot, an origami-inspired miniature robot made of multiple modules and soft/rigid backbones. Additional to the dynamic model, the effect of different sets of design parameters on the locomotion of the legged soft-bodied modular miniature robots is studied. Analyses comparing the velocity of SMoLBot with a different number of modules and various types of backbones are presented using the proposed dynamic model. Our results show the existence of an optimum backbone torsional stiffness for legged miniature modular robots and an optimum number of legs for a given backbone stiffness that maximizes the robot’s velocity. In this research, presented results and locomotion study show that the robot’s design should be iteratively improved based on specific optimum goals for exclusively defined task to satisfy the operational needs.
Open Access
Gait and locomotion analysis of a soft-hybrid multilegged modular miniature robot
(Institute of Physics Publishing Ltd., 2021-09-28) Mahkam, Nima; Özcan, Onur
The locomotion performance of the current legged miniature robots remains inferior compared to even the most simple insects. The inferiority has led researchers to utilize biological principles and control in their designs, often resulting in improved performance and robot capabilities. Additionally, optimizing the locomotion patterns compatible with the robot's limitations (such as the gaits achievable by the robot) improves the performance significantly and results in a robot operating with its maximum capabilities. This paper studies the locomotion characteristics of running/walking n-legged modular miniature robots with soft or rigid module connections. The locomotion study is done using the presented dynamic model, and the results are verified using a legged modular miniature robot with soft and rigid backbones (SMoLBot). The optimum foot contact sequences for an n-legged robot with different compliance values between the modules are derived using the locomotion analyses and the dynamic and kinematic formulations. Our investigations determine unique optimum foot contact sequences for multi-legged robots with different body compliances and module numbers. Locomotion analyses of a multi-legged robot with different backbones operating with optimum gaits show two main motion characteristics; the rigid robots minimize the number of leg-ground contacts to increase velocity, whereas soft-backbone robots use a lift–jump–fall motion sequence to maximize the translational speeds. These two behaviors are similar between different soft-backbone and rigid-backbone robots; however, the optimal foot contact sequences are different and unpredictable.
Embargo
Smolbot-VS: a soft modular robot with variable stiffness backbones
(2024-09) Uygun, Muhammed
This thesis introduces a novel mobile modular C-legged robot featuring a variable stiffness mechanism. The robot’s capability to adjust the level of compliance is achieved through a tendon-driven actuation system typically found in continuum robots. This system, in conjunction with 3D-printed soft backbones, forms the core of the robot’s modular design. A significant contribution of this work lies in developing and controlling the variable stiffness mechanism for its integration into SMoLBot. The robot design, in particular the backbone design was iteratively refined through repeated case studies, enhancing the robot’s ability to sense obstacles and optimize stiffness quantification using data from conductive backbones. The research also examined the advantages of modulating backbone stiffness, particularly in improving the robot’s performance in uneven terrain in rigid and soft configurations. The work in the thesis is concluded by detailing the implementation of a PI stiffness controller that leverages voltage feedback from the backbones to adjust the robot’s stiffness to intermediate levels. This controller allows the robot to autonomously operate variable stiffness mechanisms while demonstrating another potential use of soft sensors for mobile robots. The cyclic load tests established a correlation between voltage data from the backbones and stiffness, with force and displacement measurements confirming the relation across different stiffness levels.