• Title/Summary/Keyword: Soft contact

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A Study on Stable Grasping Control of Dual-fingers with Soft-Tips (소프트-팁이 장착된 듀얼-핑거의 안정적 파지 제어에 관한 연구)

  • 심재군;한형용;양순용;이병룡;안경관;김성수
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2002.10a
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    • pp.219-224
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    • 2002
  • This paper aims to derive a mathematical model of the dynamics of handling tasks in robot finger which stable grasping and manipulates a rigid object with some dexterity. Firstly, a set of differential equation describing dynamics of the manipulators and object together with geometric constraint of tight area-contacts is formulated by Lagrange's equation. Secondly, problems of controlling both the internal force and the rotation angle of the grasped object under the constraints of area-contacts of tight area-contacts are discussed. The effect of geometric constraints of area-contacts on motion of the overall system is analyzed and a method of computer simulation for overall system of differential-algebraic equations is presented. Thirdly, simulation results are shown and the effects of geometric constraints of area-contact is discussed. Finally, it is shown that even in the simplest case of dual single D.O.F manipulators there exists a sensory feedback from sensing data of the rotational angle of the object to command inputs to joint actuators and this feedback connection from sensing to action eventually realizes secure grasping of the object, provided that the object is of rectangular shape and motion is confined to a horizontal plane.

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The Comparison of Plantar Pressure on Double Limb Support and Single Limb Support according to Soft Surface (연성면에 따른 양발지지와 한발지지 시 족저압 비교)

  • Lee, Jeon-Hyeong;Chung, Hyeung-Jae;Kim, Shin-Gyun
    • PNF and Movement
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    • v.11 no.2
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    • pp.95-102
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    • 2013
  • Purpose : The purpose of this study was to investigate a plantar pressure distribution and the trajectory of the center of pressure on double limb support and single limb support according to level surface, air cushion, and aero step. Methods : 21 healthy adults participated in this study. The plantar pressure were assessed at three different surface conditions(on the level surface, air cushion, and aero step) on double limb support and single limb support. Testing orders were selected randomly. Results : Plantar pressure distribution show a significant difference contact area 1 and contact area 3 on double limb support and single limb support. The trajectory of the center of pressure show an significant difference anteroposterior(AP), mediolateral(ML), and total displacement on double limb support and single limb support. Conclusion : Through the use of soft surface as air cushion and aero step will be using the ankle strategy. This will be to strengthen the muscles around the ankle. Consequently, should help to improve stability and coordination.

Research of Stable Grapsing in Field Robot (Field-Robot의 안정적 파지운동 제어에 관한 연구)

  • 박경택;심재군;한현용;양순용;이병룡
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.10a
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    • pp.492-495
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    • 1997
  • This paper aims to derive a mathematical model of the dynamics of handling task in field robot which stable grasping and manipulates a rigid object with some dexterity. Firstly, a set of differential equation describing dynamics of the manipulators and object together with geometric constraints of tight area-contacts on motion of the overall system is analyzed and a method of computer simulation for overall system of differential-algebraic equations is presented. Thirdly, simulation results are shown and the effects of geometric constraints of contact-area are discussed. Finally, it is shown that even in the simplest case of dual single D.O.F. manipulators there exists a sensory feedback from sensing data of he rotational angle of the object to command inputs to joint actuators and this feedback connection from sensing to action eventually realizes secure grasping of the object, provided that he object is of rectangular shape and motion is confined to a horizontal

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Numerical Analysis of Belled Shaft Foundation in Thick Pusan Clays (대심도 부산점토에 적용된 종저말뚝(Belled Shaft foundation)의 수치해석 연구)

  • Rao, K.G.
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.530-535
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    • 2006
  • The Pusan clays are soft and thick deposits and in some places, they reach even up to 50-70m. So, the pile foundations are inevitable in almost all cases. But they are significantly expansive when the length of the pile reaches about 70m. In this study, a comprehensive parametric study has been carried out in order to reduce the pile length and number of piles required in turn the cost of the foundation for particular building. A belled shaft pile has been optimized for a typical soil profile using the PLAXIS (FEM code). These results have shown a new direction of the pile foundation in Pusan, Korea. The results including the variation of contact pressures at the bottom of the bell, optimization of the angle of the bell and height of the bell in terms of the diameter of the shaft. And also, the design curves have been generated so that they can be directly used for design of belled shaft foundations. However, the structural strength criterion is being checked in the concerned laboratory.

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Micro-channel Embedded Soft Contact Lens for Tear Biomolecule Sampling (눈물의 생체 분자 추출을 위한 미세유관이 탑재된 유연한 콘택트 렌즈)

  • Kim, Ockchul;Park, HyungDal;Song, Young-won;Kim, Jinseok
    • Journal of Biomedical Engineering Research
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    • v.37 no.5
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    • pp.178-185
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    • 2016
  • Tear is a promising biological fluid for non-invasive health monitoring. It has been studied in the past to be a possible candidate for the diagnosis of certain systemic diseases, such as breast cancer, multiple sclerosis, prostate cancer, and diabetes. However, currently existing methods for collecting and extracting tear from the human eye causes inconsistencies in the biomolecule concentrations of the tear sample due to the irritating nature of the process. In response, we designed and fabricated a microfluidic system embedded soft contact-lens for the purpose of tear sampling. The lens was then tested with artificial tear for its tear sampling capability, and found to be able to find concentration equilibrium within 50 minutes. Additionally, simulation was carried out to further optimize the design so that tear sampling rate matched the natural tear turn-over rate of 1 microliter per minute.

A Study on the Physical Properties and Adhesion Characteristics of Polyurethane Resin (폴리우레탄 수지의 물성 및 접착특성에 관한 연구)

  • Kim, Young-Joon;Chang, Ki-Young;Kim, Gu-Ni;Chun, Yong-Chul;Yoo, Chong-Sun;Park, Sang-Wook
    • Elastomers and Composites
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    • v.31 no.2
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    • pp.104-110
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    • 1996
  • The polyurethane was synthesized by the reaction of polycaprolactone diol(Mw 2000), 4,4'-diphenylmethane diisocyanate and 1,4-butanediol as the chain extender. Also, the modified polyurethane polymers based on liquid polybutadiene as a part of soft segment and dimethylolpropionic acid as a chain extender, giving polyurethane with various polarity, were synthesized. The thermal, mechanical, adhesion properties and water contact angles of the polyurethanes were examined. From the result of the water contact angle, the polarity of the acid modified PU containing 6% acid content was unchanged but mechanical and adhesion properties were improved. The water contact angles on polybutadiene modified PU films were increased with increasing polybutadiene content. The mechanical properties of the polybutadiene modified PU were higher than that of acid modified PU. However, the mechanical properties were reduced as polybutadiene content increased. The result is presumably due to phase separation between hard segment and soft segment. The peel strength of the polyurethane introduced with 5wt% polybutadiene was improved about 150% than that of unmodified PU. The same as the mechanical properties, the more polybutadiene was introduced, the lower peel strength was obtained.

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Time Domain Passivity Approach for Soft and Deformable Environments (변형 가능한 작업환경에 대한 시간영역 수동제어 방법)

  • Ryu Jee-Hwan
    • Journal of Institute of Control, Robotics and Systems
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    • v.12 no.5
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    • pp.457-463
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    • 2006
  • Recently proposed control scheme for a stable teleoperation, which was based on two-port time-domain passivity approach[21], has been successful for a contact with high stiffness environments. However, we found several conservatisms during the contact with deformable environments and unconstrained motion. The two-port time-domain passivity controller was excessively dissipating energy even though it was not necessary for some cases of an unconstrained motion and soft contact. The main reason of those conservatisms was on the fact that the two-port time-domain passivity controller was activated without considering the amount of energy dissipation at the master and slave manipulators. Especially, the exclusion of the slave manipulator from the two-port was the dominant reason of the conservatisms. In this paper, we consider the amount of energy dissipation at slave manipulator for designing the time-domain passivity observer and controller. The measured interaction force between slave manipulator and environment allow the time-domain passivity observer to include the amount of energy dissipation at the slave manipulator. Based on the modified passivity observer, reference energy following method[24] is applied to satisfy the passivity condition in real-time. The feasibility of the developed methods is proved with experiments. Improved performance is obtained for an interaction with deformable environments and an unconstrained motion.

The Effects of AFM Microcantilever Characteristics on the Non-Contact Mode Measurements (AFM 마이크로캔틸레버 특성에 따른 비접촉모드의 영향 고찰)

  • Hong, S.H.;Lee, S.I.;Lee, J.M.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.1391-1395
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    • 2006
  • In non-contact mode atomic force microscopy, the response of a resonating tip is used to measure the nanoscale topography and other properties of a sample surface. However, the tip-surface interactions can affect the tip response and destabilize the non-contact mode control. Especially it is difficult to obtain a good scanned image of high adhesion surfaces such as polymers using conventional hard NCHR tip and non-contact mode control. In this study, experimental investigation is made on the non-contact mode imaging and we report the microcantilever having low stiffness (OMCL) is useful to measure the properties of samples such as elasticity. In addition, we proved that it was adequate to use low stiffness microcantilever to obtain a good scanned image in AFM for the soft and high adhesion sample.

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Polymerization of HEMA by Electron beam Irradiation and Fabrication of Soft contact lens (전자빔조사에 의한 HEMA의 중합과 소프트콘택트렌즈 제조)

  • Hwang, Kwang-Ha;Shin, Joong-Hyeok;Sung, Yu-Jin;Jeong, Keun-Seung;Jun, Jin
    • Journal of Korean Ophthalmic Optics Society
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    • v.17 no.2
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    • pp.135-141
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    • 2012
  • Purpose: Polymerization of HEMA(2-hydroxyethyl methacrylate) which can be used in the soft contact lens has been performed by using electron beam(EB) irradiation, and examined the best condition for the polymerization. Comparing the physical properties of the contact lenses to the one fabricated by thermal polymerization method, we check the use possibility of the EB irradiation to the fabrication of the soft contact lens. Methods: We investigated the degree of polymerization of the HEMA according to the composition of the monomer, the additive ratio and the dose of electron beam (0~120 kGy). The degree of polymerization was measured depending on the EB dose to research the best synthetic condition under the EB irradiation. The physical properties of the contact lens such as water content(%), oxygen transmissibility(Dk/t) and optical transmittance were analysed by using the FT-IR results with comparing the two different polymerization method (thermal and electron beam polymerization) with same additive ratio. Results: When the dose of electron beam was above 100 kGy, the degree of polymerization of HEMA was above 99% with regardless using cross-linker and initiator. The water content of the lens fabricated by EB method showed 10% higher than the one by the thermal method which was 40%. The lens fabricated by EB method also showed higher oxygen transmissibility(Dk/t) as same with the water content, and showed twice higher value in the lens fabricated by pure HEMA. According to the FT-IR results, hydrophilic property of the lens fabricated by EB method was increased due to increasing the intermolecular hydrogen bonding. It showed above 90% optical transmittance in the visible range of wavelength on the contact lenses fabricated by the both of two different polymerization method. Conclusions: The polymerization of HEMA without cross-linker and initiator was successful above 100 kGy of EB irradiation. Moreover the lens fabricated from the polymer synthesized by pure HEMA with 100 kGy of EB showed the highest water content and oxygen transmissibility. Therefore EB irradiation is another possible method to synthesize the polymer which can be used for the soft contact lens.

Change of Spherical Aberration with Aspheric Soft Contact Lens Wear (비구면 소프트콘택트렌즈 착용에 의한 눈의 구면수차 변화)

  • Kim, Jeong Mee;Mun, Mi-Young;Kim, Young Chul;Lee, Koon-Ja
    • Journal of Korean Ophthalmic Optics Society
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    • v.17 no.4
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    • pp.365-372
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    • 2012
  • Purpose: To investigate ocular higher order aberrations (HOA) and spherical aberration changes caused by an aspheric soft contact lens designed to reduce spherical aberration (SA) of the eye. Methods: Fifty subjects who have successfully experienced soft contact lenses were refitted with aspheric design (Soflens Daily Disposable: SDD, Bausch+Lomb) soft contact lens. Ocular higher order aberrations (HOA) and stand alone SA were measured and analyzed for a 4-mm pupil size using Wave-Scan Wavefront$^{TM}$ aberrometer (VISX, Santa Clara, CA, USA). High and low contrast log MAR visual acuity and contrast sensitivity function (CSF) were also measured under photopic and mesopic conditions (OPTEC 6500 Vision Tester$^{(R)}$). All measurements were conducted monocularly with an undilated pupil. Results: The RMS mean values for total HOA with SDD contact lenses were significantly lower than those at with unaided eyes (p<0.001) and a reduction for SA in the SDD was close to the baseline SA (zero ${\mu}m$) (p<0.001). For the SDD lens, there was a statistically significant correlation between the changes in the total HOA and the contact lens power (r=0.237, p=0.018) as well as between the changes in SA and the lens power (r=0.324, p=0.001). High contrast visual acuity (HCVA) and low contrast visual acuity (LCVA) with SDD lenses were $-0.063{\pm}0.062$ and $0.119{\pm}0.060$, respectively under photopic and $-0.003{\pm}0.063$ and $0.198{\pm}0.067$, respectively under mesopic condition. Contrast Sensitivity Function (CSF) with SDD lenses under both photopic and mesopic conditions was $3.095{\pm}0.068$ and $3.087{\pm}0.074$, respectively. Conclusions: The SDD contact lens designed to control SA reduced the total ocular HOA and SA of the eye, resulting in compensating for positive SA of the eyes. Thus, the optical benefits of the lens with SA control would be adopted for improving the quality of vision.