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Design of Trimmed Helicoid Soft-Rigid Hybrid Robots

Patterson, Zach J., Sologuren, Emily R., Rus, Daniela

arXiv.org Artificial Intelligence

As soft robot design matures, researchers have converged to sophisticated design paradigms to enable the development of more suitable platforms. Two such paradigms are soft-rigid hybrid robots, which utilize rigid structural materials in some aspect of the robot's design, and architectured materials, which deform based on geometric parameters as opposed to purely material ones. In this work, we combine the two design approaches, utilizing trimmed helicoid structures in series with rigid linkages. Additionally, we extend the literature on wave spring-inspired soft structures by deriving a mechanical model of the stiffness for arbitrary geometries. We present a novel manufacturing method for such structures utilizing an injection molding approach and we make available the design tool to generate 3D printed molds for arbitrary designs of this class. Finally, we produce a robot using the above methods and operate it in closed-loop demonstrations.


Force and Speed in a Soft Stewart Platform

Ketchum, Jake, Avtges, James, Schlafly, Millicent, Young, Helena, Kim, Taekyoung, Truby, Ryan L., Murphey, Todd D.

arXiv.org Artificial Intelligence

--Many soft robots struggle to produce dynamic motions with fast, large displacements. We develop a parallel 6 degree-of-freedom (DoF) Stewart-Gough mechanism using Handed Shearing Auxetic (HSA) actuators. By using soft actuators, we are able to use one third as many mechatronic components as a rigid Stewart platform, while retaining a working payload of 2kg and an open-loop bandwidth greater than 16Hz. We show that the platform is capable of both precise tracing and dynamic disturbance rejection when controlling a ball and sliding puck using a Proportional Integral Derivative (PID) controller . We develop a machine-learning-based kinematics model and demonstrate a functional workspace of roughly 10cm in each translation direction and 28 degrees in each orientation. This 6DoF device has many of the characteristics associated with rigid components--power, speed, and total workspace-- while capturing the advantages of soft mechanisms. Soft robots promise to be safer, more resilient, and more adaptable than their rigid counterparts. This is particularly valuable for systems that are expected to touch and interact with people. However, existing soft 6 DoF parallel mechanisms struggle to produce the forces, displacements, and response times required for mass adoption [1]-[3]. A substantial driver of this capability gap is the many limitations of soft actuator technologies.


Real-Time Shape Estimation of Tensegrity Structures Using Strut Inclination Angles

Bhat, Tufail Ahmad, Yoshimitsu, Yuhei, Wada, Kazuki, Ikemoto, Shuhei

arXiv.org Artificial Intelligence

ACCEPTED MARCH, 2025 1 Real-Time Shape Estimation of Tensegrity Structures Using Strut Inclination Angles Tufail Ahmad Bhat 1, Y uhei Y oshimitsu 1, Kazuki Wada 1, Shuhei Ikemoto 1 Abstract --T ensegrity structures are becoming widely used in robotics, such as continuously bending soft manipulators and mobile robots to explore unknown and uneven environments dynamically. Estimating their shape, which is the foundation of their state, is essential for establishing control. However, on-board sensor-based shape estimation remains difficult despite its importance, because tensegrity structures lack well-defined joint structures, which makes it challenging to use conventional angle sensors such as potentiometers or encoders for shape estimation. T o our knowledge, no existing work has successfully achieved shape estimation using only onboard sensors such as Inertial Measurement Units (IMUs). This study addresses this issue by proposing a novel approach that uses energy minimization to estimate the shape. We validated our method through experiments on a simple Class 1 tensegrity structure, and the results show that the proposed algorithm can estimate the real-time shape of the structure using onboard sensors, even in the presence of external disturbances. I NTRODUCTION T HE concept of "tensegrity" is coined by the iconoclastic architect R. Buckminster Fuller. It describes structures that achieve stability through a balance of forces: specific components, known as "cables" are always in tension, while others, known as "struts" are constantly under compression [1]. In tensegrity, the cables of the structure are always under continuous tension, a condition known as "prestress".


Modelling change in neural dynamics during phonetic accommodation

Kirkham, Sam, Strycharczuk, Patrycja, Davies, Rob, Welburn, Danielle

arXiv.org Artificial Intelligence

Short-term phonetic accommodation is a fundamental driver behind accent change, but how does real-time input from another speaker's voice shape the speech planning representations of an interlocutor? We advance a computational model of change in phonetic representations during phonetic accommodation, grounded in dynamic neural field equations for movement planning and memory dynamics. We test the model's ability to capture empirical patterns from an experimental study where speakers shadowed a model talker with a different accent from their own. The experimental data shows vowel-specific degrees of convergence during shadowing, followed by return to baseline (or minor divergence) post-shadowing. The model can reproduce these phenomena by modulating the magnitude of inhibitory memory dynamics, which may reflect resistance to accommodation due to phonological and/or sociolinguistic pressures. We discuss the implications of these results for the relation between short-term phonetic accommodation and longer-term patterns of sound change.


Development and Comparison of Model-Based and Data-Driven Approaches for the Prediction of the Mechanical Properties of Lattice Structures

Pasini, Chiara, Ramponi, Oscar, Pandini, Stefano, Sartore, Luciana, Scalet, Giulia

arXiv.org Artificial Intelligence

Lattice structures have great potential for several application fields ranging from medical and tissue engineering to aeronautical one. Their development is further speeded up by the continuing advances in additive manufacturing technologies that allow to overcome issues typical of standard processes and to propose tailored designs. However, the design of lattice structures is still challenging since their properties are considerably affected by numerous factors. The present paper aims to propose, discuss, and compare various modeling approaches to describe, understand, and predict the correlations between the mechanical properties and the void volume fraction of different types of lattice structures fabricated by fused deposition modeling 3D printing. Particularly, four approaches are proposed: (i) a simplified analytical model; (ii) a semi-empirical model combining analytical equations with experimental correction factors; (iii) an artificial neural network trained on experimental data; (iv) numerical simulations by finite element analyses. The comparison among the various approaches, and with experimental data, allows to identify the performances, advantages, and disadvantages of each approach, thus giving important guidelines for choosing the right design methodology based on the needs and available data.


Adaptable, shape-conforming robotic endoscope

Du, Jiayang, Cao, Lin, Dogramazi, Sanja

arXiv.org Artificial Intelligence

This paper introduces a size-adaptable robotic endoscope design, which aims to improve the efficiency and comfort of colonoscopy. The robotic endoscope proposed in this paper combines the expansion mechanism and the external drive system, which can adjust the shape according to the different pipe diameters, thus improving the stability and propulsion force during propulsion. As an actuator in the expansion mechanism, flexible bellows can provide a normal force of 3.89 N and an axial deformation of nearly 10mm at the maximum pressure, with a 53% expansion rate in the size of expandable tip. In the test of the locomotion performance of the prototype, we obtained the relationship with the propelling of the prototype by changing the friction coefficient of the pipe and the motor angular velocity. In the experiment with artificial bowel tissues, the prototype can generate a propelling force of 2.83 N, and the maximum linear speed is 29.29 m/s in average, and could produce effective propulsion when it passes through different pipe sizes. The results show that the prototype can realize the ability of shape adaptation in order to obtain more propulsion. The relationship between propelling force and traction force, structural optimization and miniaturization still need further exploration.


A Novel Design and Improvement of 15-Bar Assembly Tensegrity Robotics Structure

Chu, Yunyi

arXiv.org Artificial Intelligence

While the ultimate goal is to produce a tensegrity more than 6 struts, e.g. a 15-bar tensegrity, past experience has demonstrated that we must first develop an innovative system that will facilitate the assembly of a general n-bar tensegrity. To be successful, we believe the development of the new assembly methodology must encompass not only the design of the clamping system but also the design of the tensegrity itself, including the struts, the springs and the spring-to-strut connectors. We therefore propose to develop the 15-bar in two phases: Phase I will be the development of an innovative assembly method, and Phase II will focus on the design and manufacture of a 15-bar tensegrity, with a new strut design probably being part of this. Longer term goals will be aimed at repackaging the wireless electronics on the new struts and adding encoders to control the phase of the motors shafts.


Effect of boundary conditions on a high-performance isolation hexapod platform

Stabile, Alessandro, Yotov, Vladimir V., Aglietti, Guglielmo S., De Francesco, Pasquale, Richardson, Guy

arXiv.org Artificial Intelligence

Isolation of spacecraft microvibrations is essential for the successful deployment of instruments relying on high-precision pointing. Hexapod platforms represent a promising solution, but the difficulties associated with attaining desirable 3D dynamics within acceptable mass and complexity budgets have led to a minimal practical adoption. This paper addresses the influence of strut boundary conditions (BCs) on system-level mechanical disturbance suppression. Inherent limitations of the traditional all-rotational joint configuration are highlighted and shown to originate in link mass and rotational inertia. A pin-slider BC alternative is proposed and analytically proven to alleviate them in both 2D and 3D. The advantages of the new BC hold for arbitrary parallel manipulators and are demonstrated for several hexapod geometries through numerical tests. A configuration with favourable performance is suggested. Finally, a novel planar joint that allows the physical realisation of the proposed BC is described and validated. Consequently, this work enables the development of platforms for microvibration attenuation that do not require active control.


AI-driven robots are making new materials, improving solar cells and other technologies

#artificialintelligence

BOSTON--In July 2018, Curtis Berlinguette, a materials scientist at the University of British Columbia in Vancouver, Canada, realized he was wasting his graduate student's time and talent. He had asked her to refine a key material in solar cells to boost its electrical conductivity. But the number of potential tweaks was overwhelming, from spiking the recipe with traces of metals and other additives to varying the heating and drying times. "There are so many things you can go change, you can quickly go through 10 million [designs] you can test," Berlinguette says. So he and colleagues outsourced the effort to a single-armed robot overseen by an artificial intelligence (AI) algorithm.


Researchers designed a shape-shifting airplane wing

Engadget

If you've had a window seat next to the wing of an airplane, you've probably watched as flaps on the wing engage and disengage as a plane takes off and lands. That's because in each phase of flight -- take off, landing, cruising and maneuvering -- the ideal wing parameters vary. Until now, we've made do by modifying rigid wings with hinged surfaces. But imagine if the entire wing could change shape -- that's what researchers led by NASA and MIT are working towards. In a paper in the journal Smart Materials and Structures, the research team explains how it has radically redesigned the airplane wing.