27,495 research outputs found

    A novel model for layer jamming-based continuum robots

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    Continuum robots with variable stiffness have gained wide popularity in the last decade. Layer jamming (LJ) has emerged as a simple and efficient technique to achieve tunable stiffness for continuum robots. Despite its merits, the development of a control-oriented dynamical model tailored for this specific class of robots remains an open problem in the literature. This paper aims to present the first solution, to the best of our knowledge, to close the gap. We propose an energy-based model that is integrated with the LuGre frictional model for LJ-based continuum robots. Then, we take a comprehensive theoretical analysis for this model, focusing on two fundamental characteristics of LJ-based continuum robots: shape locking and adjustable stiffness. To validate the modeling approach and theoretical results, a series of experiments using our \textit{OctRobot-I} continuum robotic platform was conducted. The results show that the proposed model is capable of interpreting and predicting the dynamical behaviors in LJ-based continuum robots

    Efficient RRT*-based Safety-Constrained Motion Planning for Continuum Robots in Dynamic Environments

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    Continuum robots, characterized by their high flexibility and infinite degrees of freedom (DoFs), have gained prominence in applications such as minimally invasive surgery and hazardous environment exploration. However, the intrinsic complexity of continuum robots requires a significant amount of time for their motion planning, posing a hurdle to their practical implementation. To tackle these challenges, efficient motion planning methods such as Rapidly Exploring Random Trees (RRT) and its variant, RRT*, have been employed. This paper introduces a unique RRT*-based motion control method tailored for continuum robots. Our approach embeds safety constraints derived from the robots' posture states, facilitating autonomous navigation and obstacle avoidance in rapidly changing environments. Simulation results show efficient trajectory planning amidst multiple dynamic obstacles and provide a robust performance evaluation based on the generated postures. Finally, preliminary tests were conducted on a two-segment cable-driven continuum robot prototype, confirming the effectiveness of the proposed planning approach. This method is versatile and can be adapted and deployed for various types of continuum robots through parameter adjustments

    Kinematic Synthesis in the Design of Continuum Robots

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    Continuum robots are a type of robot composed of multiple sections that bend continuously along their elastic structures. Because of this, these robots are typically referred to as “snake-like”. Due to their soft structure, continuum robots have many significant advantages over conventional serial robots: flexibility, compliance, and dexterity. With these capabilities, continuum robots are well-suited for minimally invasive surgery, search and rescue operations, and a variety of inspection tasks. However, the additional complexity of continuum robots introduces a new set of synthesis challenges as compared to their rigid counterparts. In this research, we focus on the inverse kinematics (IK) problem as a first step in addressing the synthesis (or design) challenge for creating a continuum robot. The IK problem seeks to determine how to position a robot given a desired location and/or an orientation for the gripper at the end of the robot. The IK problem for complicated systems like a continuum robot is typically solved with time-consuming and complicated numerical methods. This research approaches a novel and fast method to solve the IK problem by exploiting the snake-like curve, called the backbone, described by a configuration of the robot. Using techniques from spatial rigid-body shape-changing mechanism theory, this research intends to reduce the complexity of calculating an approximate solution to this IK challenge.https://ecommons.udayton.edu/stander_posters/3747/thumbnail.jp

    Continuum Surrogate Software Interface for Teleoperation of Continuum Robots

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    This thesis presents a novel teleoperation interface for continuum robots. Previous tele-operation interface methods for continuum robots did not include a natural mapping due to a degree-of-freedom mismatch, using non continuum input devices with fewer degrees-of-freedom than the robot that was being controlled. The approach introduced in this thesis involves creating a 3D model of the robot using graphics libraries and a continuum kinematic model, then manipulating that graphical 3D model on screen to directly control the continuum robot. This thesis details the development of both the model and software. The teleoperation interface was developed specifi-cally for a nine degree-of-freedom pneumatically-driven extensible continuum robot (OctArm), but it applies to any continuum robot with an arbitrary number of sections due to its modular design. Experiments using the aforementioned system on two different continuum robots are reported and areas for future work and improvement are detailed

    Simultaneous Position-and-Stiffness Control of Underactuated Antagonistic Tendon-Driven Continuum Robots

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    Continuum robots have gained widespread popularity due to their inherent compliance and flexibility, particularly their adjustable levels of stiffness for various application scenarios. Despite efforts to dynamic modeling and control synthesis over the past decade, few studies have focused on incorporating stiffness regulation in their feedback control design; however, this is one of the initial motivations to develop continuum robots. This paper aims to address the crucial challenge of controlling both the position and stiffness of a class of highly underactuated continuum robots that are actuated by antagonistic tendons. To this end, the first step involves presenting a high-dimensional rigid-link dynamical model that can analyze the open-loop stiffening of tendon-driven continuum robots. Based on this model, we propose a novel passivity-based position-and-stiffness controller adheres to the non-negative tension constraint. To demonstrate the effectiveness of our approach, we tested the theoretical results on our continuum robot, and the experimental results show the efficacy and precise performance of the proposed methodology

    Approximate Piecewise Constant Curvature Equivalent Model and Their Application to Continuum Robot Configuration Estimation

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    The continuum robot has attracted more attention for its flexibility. Continuum robot kinematics models are the basis for further perception, planning, and control. The design and research of continuum robots are usually based on the assumption of piecewise constant curvature (PCC). However, due to the influence of friction, etc., the actual motion of the continuum robot is approximate piecewise constant curvature (APCC). To address this, we present a kinematic equivalent model for continuum robots, i.e. APCC 2L-5R. Using classical rigid linkages to replace the original model in kinematic, the APCC 2L-5R model effectively reduces complexity and improves numerical stability. Furthermore, based on the model, the configuration self-estimation of the continuum robot is realized by monocular cameras installed at the end of each approximate constant curvature segment. The potential of APCC 2L-5R in perception, planning, and control of continuum robots remains to be explored

    Kinematic Synthesis in the Design of Continuum Robots

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    Continuum robots represent a new type of flexible and elastic robot that offers a range of advantages over their rigid-bodied counterparts. Their ability to bend, twist, and stretch similarly to biological organisms makes them ideal for navigating complex and confined environments, adapting to changing shapes and surfaces, and interacting with delicate objects without causing damage. With a diverse range of potential applications, including medical procedures and surgeries, as well as industrial inspection and maintenance, continuum robots are a fascinating area of research and development in robotics. However, the additional complexity introduced by continuum robots has led to a new set of synthesis challenges, specifically regarding their kinematics. Solving the inverse kinematics problem is crucial for enabling precise control and manipulation of these robots, allowing them to achieve the desired location and orientation of the gripper at the end of the robot. To address these challenges, this study seeks to develop advanced models and programming techniques for continuum robots that are capable of matching the near-term designs being considered. Building on the prior research conducted by DIMLab, the research aims to gain a comprehensive understanding of the kinematics of continuum robots, allowing them to be applied in a variety of contexts with greater accuracy and precision.https://ecommons.udayton.edu/stander_posters/3911/thumbnail.jp

    Verification of a Three-Dimensional Statics Model for Continuum Robotics and the Design and Construction of a Small Continuum Robot (SCR)

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    Continuum robots are biologically inspired robots that capture the extraordinary abilities of biological structures such as elephant trunks, octopus tentacles, and mamma-lian tongues. They are given the term continuum robots due to their ability to bend conti-nuously rather than at specific joints such as with traditional rigid link robots. They are used in applications such as search and rescue operations, nuclear reactor repairs, colo-noscopies, minimal invasive surgeries, and steerable needles. In this thesis, a model that predicts the shape of a continuum robot is presented and verified. A verification system to verify the validity and accuracy of the model is presented which allows easy and accu-rate measurement of a continuum robot tip position. The model was verified against a flexible rod, the core component of a continuum robot, resulting in an accuracy of 0.61%. Finally, this thesis introduces a novel robot design, consisting of a single rod for the backbone which can be manipulated by applying external forces and torques

    Continuum Robots for Space Applications Based on Layer-Jamming Scales with Stiffness Capability

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    Continuum robots, which have continuous mechanical structures comparable to the flexibility in elephant trunks and octopus arms, have been primarily geared toward the medical and defense communities. In space, however, NASA projects these robots to have a place in irregular inspection routines. The inherent compliance and bending of these continuum arms are especially suitable for inspection in obstructed spaces to ensure proper equipment functionality. In this paper, we propose a new solution that improves on the functionality of previous continuum robots, via a novel mechanical scaly layer-jamming design. Layer-jamming assisted continuum arms have previously required pneumatic sources for actuation, which limit their portability and usage in aerospace applications. This paper combines the compliance of continuum arms and stiffness modulation of the layer jamming mechanism to design new hybrid layer jamming continuum arms. The novel designs use an electromechanical actuation which eliminates the previous need for pneumatic actuation therefore making the hardware compact and portable
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