25,286 research outputs found

    Roller drive materials performance

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    Roller traction performance basics, a test program to measure performance, and the need for and typical use of the information are outlined. A test rig was designed and fabricated to develop this information. Parametric conditions and specimen materials were chosen so that the resulting data will be valuable to the design and development of advanced, roller-driven space mechanisms, from precision positioning devices to telerobot joints

    Conceptual design and analysis of roads and road construction machinery for initial lunar base operations

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    Recent developments have made it possible for scientists and engineers to consider returning to the Moon to build a manned lunar base. The base can be used to conduct scientific research, develop new space technology, and utilize the natural resources of the Moon. Areas of the base will be separated, connected by a system of roads that reduce the power requirements of vehicles traveling on them. Feasible road types for the lunar surface were analyzed and a road construction system was designed for initial lunar base operations. A model was also constructed to show the system configuration and key operating features. The alternate designs for the lunar road construction system were developed in four stages: analyze and select a road type; determine operations and machinery needed to produce the road; develop machinery configurations; and develop alternates for several machine components. A compacted lunar soil road was selected for initial lunar base operations. The only machinery required to produce this road were a grader and a compactor. The road construction system consists of a main drive unit which is used for propulsion, a detachable grader assembly, and a towed compactor

    Actuators for a space manipulator

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    The robotic manipulator can be decomposed into distinct subsytems. One particular area of interest of mechanical subsystems is electromechanical actuators (or drives). A drive is defined as a motor with an appropriate transmission. An overview is given of existing, as well as state-of-the-art drive systems. The scope is limited to space applications. A design philosophy and adequate requirements are the initial steps in designing a space-qualified actuator. The focus is on the d-c motor in conjunction with several types of transmissions (harmonic, tendon, traction, and gear systems). The various transmissions will be evaluated and key performance parameters will be addressed in detail. Included in the assessment is a shuttle RMS joint and a MSFC drive of the Prototype Manipulator Arm. Compound joints are also investigated. Space imposes a set of requirements for designing a high-performance drive assembly. Its inaccessibility and cryogenic conditions warrant special considerations. Some guidelines concerning these conditions are present. The goal is to gain a better understanding in designing a space actuator

    A multisensing setup for the intelligent tire monitoring

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    The present paper offers the chance to experimentally measure, for the first time, the internal tire strain by optical fiber sensors during the tire rolling in real operating conditions. The phenomena that take place during the tire rolling are in fact far from being completely understood. Despite several models available in the technical literature, there is not a correspondently large set of experimental observations. The paper includes the detailed description of the new multi-sensing technology for an ongoing vehicle measurement, which the research group has developed in the context of the project OPTYRE. The experimental apparatus is mainly based on the use of optical fibers with embedded Fiber Bragg Gratings sensors for the acquisition of the circumferential tire strain. Other sensors are also installed on the tire, such as a phonic wheel, a uniaxial accelerometer, and a dynamic temperature sensor. The acquired information is used as input variables in dedicated algorithms that allow the identification of key parameters, such as the dynamic contact patch, instantaneous dissipation and instantaneous grip. The OPTYRE project brings a contribution into the field of experimental grip monitoring of wheeled vehicles, with implications both on passive and active safety characteristics of cars and motorbikes

    On line estimation of rolling resistance for intelligent tires

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    The analysis of a rolling tire is a complex problem of nonlinear elasticity. Although in the technical literature some tire models have been presented, the phenomena involved in the tire rolling are far to be completely understood. In particular, small knowledge comes even from experimental direct observation of the rolling tire, in terms of dynamic contact patch, instantaneous dissipation due to rubber-road friction and hysteretic behavior of the tire structure, and instantaneous grip. This paper illustrates in details a new powerful technology that the research group has developed in the context of the project OPTYRE. A new wireless optical system based on Fiber Bragg Grating strain sensors permits a direct observation of the inner tire stress when rolling in real conditions on the road. From this information, following a new suitably developed tire model, it is possible to identify the instant area of the contact patch, the grip conditions as well the instant dissipation, which is the object of the present work

    Compliant rolling-contact architected materials for shape reconfigurability.

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    Architected materials can achieve impressive shape-changing capabilities according to how their microarchitecture is engineered. Here we introduce an approach for dramatically advancing such capabilities by utilizing wrapped flexure straps to guide the rolling motions of tightly packed micro-cams that constitute the material's microarchitecture. This approach enables high shape-morphing versatility and extreme ranges of deformation without accruing appreciable increases in strain energy or internal stress. Two-dimensional and three-dimensional macroscale prototypes are demonstrated, and the analytical theory necessary to design the proposed materials is provided and packaged as a software tool. An approach that combines two-photon stereolithography and scanning holographic optical tweezers is demonstrated to enable the fabrication of the proposed materials at their intended microscale

    ์‚ฌ๋žŒ ๊ทผ๊ณจ๊ฒฉ ํŠน์„ฑ์„ ๋ฐ˜์˜ํ•œ ๋กœ๋ด‡ ์†๊ฐ€๋ฝ ์„ค๊ณ„

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    ํ•™์œ„๋…ผ๋ฌธ(๋ฐ•์‚ฌ) -- ์„œ์šธ๋Œ€ํ•™๊ต๋Œ€ํ•™์› : ์œตํ•ฉ๊ณผํ•™๊ธฐ์ˆ ๋Œ€ํ•™์› ์œตํ•ฉ๊ณผํ•™๋ถ€(์ง€๋Šฅํ˜•์œตํ•ฉ์‹œ์Šคํ…œ์ „๊ณต), 2023. 2. ๋ฐ•์žฌํฅ.What the manipulator can perform is determined by what the end-effectors, including the robotic hand, can do because it is the gateway that directly interacts with the surrounding environment or objects. In order for robots to have human-level task performance in a human-centered environment, the robotic hand with human-hand-level capabilities is essential. Here, the human-hand-level capabilities include not only force-speed, and dexterity, but also size and weight. However, to our knowledge, no robotic hand exists that simultaneously realizes the weight, size, force, and dexterity of the human hand and continues to remain a challenge. In this thesis, to improve the performance of the robotic hand, the modular robotic finger design with three novel mechanisms based on the musculoskeletal characteristics of the human hand was proposed. First, the tendon-driven robotic finger with intrinsic/extrinsic actuator arrangement like the muscle arrangement of the human hand was proposed and analyzed. The robotic finger consists of five different tendons and ligaments. By analyzing the fingertip speed while a human is performing various object grasping motions, the actuators of the robotic finger were separated into intrinsic actuators responsible for slow motion and an extrinsic actuator that performs the motions requiring both large force and high speed. Second, elastomeric continuously variable transmission (ElaCVT), a new concept relating to continuously variable transmission (CVT), was designed to improve the performance of the electric motors remaining weight and size and applied as an extrinsic actuator of the robotic finger. The primary purpose of ElaCVT is to expand the operating region of a twisted string actuator (TSA) and duplicate the force-velocity curve of the muscles by passively changing the reduction ratio according to the external load applied to the end of the TSA. A combination of ElaCVT and TSA (ElaCVT-TSA) is proposed as a linear actuator. With ElaCVT-TSA, an expansion of the operating region of electric motors to the operating region of the muscles was experimentally demonstrated. Finally, as the flexion/extension joints of the robotic finger, anthropomorphic rolling contact joint, which mimicked the structures of the human finger joint like tongue-and-groove, and collateral ligaments, was proposed. As compliant joints not only compensate for the lack of actuated degrees of freedom of an under-actuated system and improve grasp stability but also prevent system failure from unexpected contacts, various types of compliant joints have been applied to end-effectors. Although joint compliance increases the success rate of power grasping, when the finger wraps around large objects, it can reduce the grasping success rate in pinch gripping when dealing with small objects using the fingertips. To overcome this drawback, anthropomorphic rolling contact joint is designed to passively adjust the torsional stiffness according to the joint angle without additional weight and space. With the anthropomorphic rolling contact joint, the stability of pinch grasping improved.์—”๋“œ์ดํŒฉํ„ฐ๋Š” ๋กœ๋ด‡๊ณผ ์ฃผ๋ณ€ ํ™˜๊ฒฝ์ด ์ƒํ˜ธ์ž‘์šฉํ•˜๋Š” ํ†ต๋กœ๋กœ ๋งค๋‹ˆํ“ฐ๋ ˆ์ดํ„ฐ๊ฐ€ ์ˆ˜ํ–‰ํ•  ์ˆ˜ ์žˆ๋Š” ์ž‘์—…์€ ์—”๋“œ์ดํŽ™ํ„ฐ์˜ ์„ฑ๋Šฅ์— ์ œํ•œ๋œ๋‹ค. ์‚ฌ๋žŒ ์ค‘์‹ฌ์˜ ํ™˜๊ฒฝ์— ๋กœ๋ด‡์ด ์ ์šฉ๋˜์–ด ์‚ฌ๋žŒ ์ˆ˜์ค€์˜ ๋‹ค์–‘ํ•œ ์ž‘์—…์„ ์ˆ˜ํ–‰ํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ์‚ฌ๋žŒ ์† ์ˆ˜์ค€์˜ ์„ฑ๋Šฅ์„ ๊ฐ–๋Š” ๋กœ๋ด‡ ์†์ด ํ•„์ˆ˜์ ์ด๋ฉฐ ์‚ฌ๋žŒ ์† ์ˆ˜์ค€์˜ ์„ฑ๋Šฅ์€ ๋‹จ์ˆœํžˆ ํž˜-์†๋„, ์ž์œ ๋„๋งŒ์„ ํฌํ•จํ•˜๋Š” ๊ฒƒ์ด ์•„๋‹Œ ํฌ๊ธฐ์™€ ๋ฌด๊ฒŒ ๊ทธ๋ฆฌ๊ณ  ๋ฌผ์ฒด ์กฐ์ž‘์— ๋„์›€์„ ์ฃผ๋Š” ์—ฌ๋Ÿฌ ์† ํŠน์„ฑ๋„ ํฌํ•จํ•œ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ํ˜„์žฌ๊นŒ์ง€ ์‚ฌ๋žŒ ์† ์ˆ˜์ค€์˜ ๋ฌด๊ฒŒ, ํฌ๊ธฐ, ํž˜ ๊ทธ๋ฆฌ๊ณ  ์ž์œ ๋„๋ฅผ ๋ชจ๋‘ ๋งŒ์กฑ์‹œํ‚ค๋Š” ๋กœ๋ด‡ ์†์€ ๊ฐœ๋ฐœ๋˜์ง€ ์•Š์•˜์œผ๋ฉฐ ์—ฌ์ „ํžˆ ๋„์ „์ ์ธ ๊ณผ์ œ๋กœ ๋‚จ์•„์žˆ๋‹ค. ๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” ๋กœ๋ด‡ ์†๊ฐ€๋ฝ์˜ ์„ฑ๋Šฅ์„ ํ–ฅ์ƒํ•˜๊ธฐ ์œ„ํ•˜์—ฌ ์‚ฌ๋žŒ์˜ ๊ทผ๊ณจ๊ฒฉ ํŠน์„ฑ์„ ๋ฐ˜์˜ํ•œ ์„ธ ๊ฐ€์ง€์˜ ์ƒˆ๋กœ์šด ๋ฉ”์ปค๋‹ˆ์ฆ˜์„ ์ œ์•ˆํ•˜๊ณ  ์ด๋ฅผ ํ†ตํ•ฉํ•œ ๋ชจ๋“ˆํ˜• ๋กœ๋ด‡ ์†๊ฐ€๋ฝ ๊ตฌ์กฐ๋ฅผ ๋ณด์ธ๋‹ค. ์ฒซ ๋ฒˆ์งธ๋กœ, ์‚ฌ๋žŒ์˜ ์† ๊ทผ์œก ๋ฐฐ์น˜์™€ ์œ ์‚ฌํ•œ ๋‚ด์žฌ/์™ธ์žฌ ๊ตฌ๋™๊ธฐ ๋ฐฐ์น˜๋ฅผ ์ ์šฉํ•œ ํž˜์ค„ ๊ตฌ๋™ ๋กœ๋ด‡ ์†๊ฐ€๋ฝ ๊ตฌ์กฐ๋ฅผ ์ œ์•ˆํ•˜๊ณ  ๋ถ„์„ํ•œ๋‹ค. ๋กœ๋ด‡ ์†๊ฐ€๋ฝ์€ ๋‹ค์„ฏ ๊ฐœ์˜ ์„œ๋กœ ๋‹ค๋ฅธ ํž˜์ค„๊ณผ ์ธ๋Œ€๋กœ ๊ตฌ์„ฑ๋œ๋‹ค. ์‚ฌ๋žŒ ์†๋™์ž‘ ๋ถ„์„์— ๊ธฐ๋ฐ˜ํ•˜์—ฌ ๋กœ๋ด‡ ์†๊ฐ€๋ฝ์˜ ๊ตฌ๋™๊ธฐ๋Š” ๋Š๋ฆฐ ์†๋„๋ฅผ ๋‹ด๋‹นํ•˜๋Š” ๋‚ด์žฌ ๊ตฌ๋™๊ธฐ์™€ ๋น ๋ฅด๊ณ  ํฐ ํž˜์ด ๋ชจ๋‘ ์š”๊ตฌ๋˜๋Š” ์™ธ์žฌ ๊ตฌ๋™๊ธฐ๋กœ ๊ตฌ๋ถ„๋œ๋‹ค. ๋‘ ๋ฒˆ์งธ๋กœ, ๊ตฌ๋™๊ธฐ์˜ ํฌ๊ธฐ์™€ ๋ฌด๊ฒŒ๋ฅผ ์œ ์ง€ํ•˜๋ฉฐ ์„ฑ๋Šฅ์„ ํ–ฅ์ƒํ•˜๊ธฐ ์œ„ํ•˜์—ฌ ์ƒˆ๋กœ์šด ๊ฐœ๋…์˜ ๋ฌด๋‹จ ๋ณ€์†๊ธฐ Elastomeric Continuously Variable Transmission (ElaCVT) ์„ ์ œ์•ˆํ•˜๊ณ  ์ด๋ฅผ ๋กœ๋ด‡ ์†๊ฐ€๋ฝ์˜ ์™ธ์žฌ ๊ตฌ๋™๊ธฐ์— ์ ์šฉํ•˜์˜€๋‹ค. ElaCVT๋Š” ์„ ํ˜• ๊ตฌ๋™๊ธฐ์˜ ์ž‘๋™ ์˜์—ญ์„ ํ™•์žฅํ•˜๊ณ  ์ถœ๋ ฅ๋‹จ์— ๊ฐ€ํ•ด์ง€๋Š” ์™ธ๋ถ€ ํ•˜์ค‘์— ๋”ฐ๋ผ ๊ฐ์†๋น„๋ฅผ ์ˆ˜๋™์ ์œผ๋กœ ๋ณ€๊ฒฝํ•˜์—ฌ ๊ทผ์œก์˜ ํž˜-์†๋„ ๊ณก์„ ์„ ๋ชจ์‚ฌํ•  ์ˆ˜ ์žˆ๋‹ค. ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ๊ทผ์œก์˜ ํŠน์„ฑ์„ ๋ชจ์‚ฌํ•˜๊ธฐ ์œ„ํ•ด ์„ ํ˜• ์•ก์ถ”์—์ดํ„ฐ๋กœ ElaCVT์— ์ค„ ๊ผฌ์ž„ ๋ฉ”์ปค๋‹ˆ์ฆ˜์„ ์ ์šฉํ•œ ElaCVT-TSA๋ฅผ ์ œ์•ˆ, ๊ทผ์œก์˜ ๋™์ž‘ ์˜์—ญ์„ ๋ชจ์‚ฌํ•  ์ˆ˜ ์žˆ์Œ์„ ๋ณด์˜€๋‹ค. ๋งˆ์ง€๋ง‰์œผ๋กœ ๋กœ๋ด‡ ์†๊ฐ€๋ฝ์˜ ๋ชจ๋“  ๊ตฝํž˜/ํŽผ์นจ ๊ด€์ ˆ์— ์ ์šฉ๋œ ์‚ฌ๋žŒ์˜ ๊ด€์ ˆ๊ตฌ์กฐ๋ฅผ ๋ชจ์‚ฌํ•œ ์œ ์—ฐ ๊ตฌ๋ฆ„ ์ ‘์ด‰ ๊ด€์ ˆ (Anthropomorphic Rolling Contact joint)์„ ์ œ์•ˆํ•œ๋‹ค. Anthropomorphic rolling contact joint๋Š” ์‚ฌ๋žŒ ๊ด€์ ˆ์˜ tongue-and-groove ํ˜•์ƒ๊ณผ collateral ligament๋ฅผ ๋ชจ์‚ฌํ•˜์—ฌ ๊ด€์ ˆ์˜ ์•ˆ์ •์„ฑ์„ ํ–ฅ์ƒ์‹œ์ผฐ๋‹ค. ๊ธฐ์กด์˜ ์œ ์—ฐ ๊ด€์ ˆ๊ณผ ๋‹ฌ๋ฆฌ ๊ด€์ ˆ์ด ํŽด์ง„ ์ƒํƒœ์—์„œ๋Š” ์œ ์—ฐํ•œ ์ƒํƒœ๋ฅผ ์œ ์ง€ํ•˜๋ฉฐ ๊ตฝํ˜€์ง„ ์ƒํƒœ์—์„œ๋Š” ๊ฐ•์„ฑ์ด ์ฆ๊ฐ€ํ•œ๋‹ค๋Š” ํŠน์ง•์„ ๊ฐ–๋Š”๋‹ค. ํŠนํžˆ, ๊ฐ•์„ฑ ๋ณ€ํ™”์— ๋ณ„๋„์˜ ๊ตฌ๋™๊ธฐ๊ฐ€ ์š”๊ตฌ๋˜์ง€ ์•Š์•„ ๊ธฐ์กด์˜ ๊ด€์ ˆ์—์„œ ๋ฌด๊ฒŒ, ํฌ๊ธฐ ์ฆ๊ฐ€ ์—†์ด ํ•ด๋‹น ํŠน์ง• ๊ตฌํ˜„์ด ๊ฐ€๋Šฅํ•˜๋‹ค. ์ด๋Š” ๋กœ๋ด‡ ์†๊ฐ€๋ฝ์— ์ ์šฉ๋˜์–ด ์†๊ฐ€๋ฝ์„ ํŽด๊ณ  ๋ฌผ์ฒด๋ฅผ ํƒ์ƒ‰ํ•˜๋Š” ๊ณผ์ •์—์„œ๋Š” ์ถฉ๊ฒฉ์„ ํก์ˆ˜ํ•˜์—ฌ ์•ˆ์ •์ ์ธ ์ ‘์ด‰์„ ๊ตฌํ˜„ํ•  ์ˆ˜ ์žˆ์œผ๋ฉฐ ๋ฌผ์ฒด๋ฅผ ํŒŒ์ง€ํ•˜๋Š” ๊ณผ์ •์—์„œ๋Š” ์†๊ฐ€๋ฝ์„ ๊ตฝํ˜€ ๊ฐ•์ธํ•˜๊ฒŒ ๋ฌผ์ฒด๋ฅผ ํŒŒ์ง€ํ•  ์ˆ˜ ์žˆ๊ฒŒ ํ•œ๋‹ค. Anthropomorphic rolling contact joint๋ฅผ ์ ์šฉํ•œ ๊ทธ๋ฆฝํผ๋ฅผ ์ด์šฉํ•˜์—ฌ ์ œ์•ˆํ•˜๋Š” ๊ฐ€๋ณ€ ๊ฐ•์„ฑ ์œ ์—ฐ ๊ด€์ ˆ์ด pinch grasping์˜ ํŒŒ์ง€ ์•ˆ์ •์„ฑ์„ ๋†’์ž„์„ ๋ณด์˜€๋‹ค.1 INTRODUCTION 1 1.1 MOTIVATION: ROBOTIC HANDS 1 1.2 CONTRIBUTIONS OF THESIS 10 1.2.1 Intrinsic/Extrinsic Actuator arrangement 11 1.2.2 Linear actuator mimicking human muscle properties 11 1.2.3 Flexible rolling contact joint 12 2 ROBOTIC FINGER STRUCTURE WITH HUMAN-LIKE ACTUATOR ARRANGEMENT 13 2.1 ANALYSIS OF HUMAN FINGERTIP VELOCITY 14 2.2 THE ROBOTIC FINGER WITH INTRINSIC/EXTRINSIC ACTUATORS 18 2.2.1 The structure of proposed robotic finger 18 2.2.2 Kinematics of the robotic finger 20 2.2.3 Tendons and Ligaments of the proposed robotic finger 26 2.2.4 Decoupled fingertip motion in the sagittal plane 28 3 ELASTOMERIC CONTINUOUSLY VARIABLE TRANSMISSION COMBINED WITH TWISTED STRING ACTUATOR 35 3.1 BACKGROUND & RELATED WORKS 35 3.2 COMPARISON OF OPERATING REGIONS 40 3.3 DESIGN OF THE ELASTOMERIC CONTINUOUSLY VARIABLE TRANSMISSION 42 3.3.1 Structure of ElaCVT 42 3.3.2 Design of Elastomer and Lateral Disc 43 3.3.3 Advantages of ElaCVT 48 3.4 PERFORMANCE EVALUATION 50 3.4.1 Experimental Setup 50 3.4.2 Contraction with Fixed external load 50 3.4.3 Contraction with Variable external load 55 3.4.4 Performance variation of ElaCVT over long term usage 55 3.4.5 Specifications and Limitations of ElaCVT-TSA 59 4 ANTHROPOMORPHIC ROLLING CONTACT JOINT 61 4.1 INTRODUCTION: COMPLIANT JOINT 61 4.2 RELATED WORKS: ROLLING CONTACT JOINT 65 4.3 ANTHROPOMORPHIC ROLLING CONTACT JOINT 67 4.3.1 Fundamental Components of ARC joint 69 4.3.2 Advantages of ARC joint 73 4.4 TORSIONAL STIFFNESS EVALUATION 75 4.4.1 Experimental Setup 75 4.4.2 Design and Manufacturing of ARC joints 77 4.4.3 Torsional Stiffness Change according to Joint Angle and Twist Angle 79 4.5 TORSIONAL STIFFNESS WITH JOINT COMPRESSION FORCE DUE TO TNESION OF TENDONS 80 4.6 TORSIONAL STIFFNESS WITH LUBRICATION STRUCTURE 82 4.7 GRASPING PERFORMANCE COMPARISON OF GRIPPERS WITH DIFFERENT ARC JOINTS 86 5 CONCLUSIONS 92 Abstract (In Korean) 107๋ฐ•

    NASA helicopter transmission system technology program

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    The purpose of the NASA Helicopter Transmission System Technology Program is to improve specific mechanical components and the technology for combining these into advanced drive systems to make helicopters more viable and cost competitive for commerical applications. The history, goals, and elements of the program are discussed
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