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Jae-bok Song - One of the best experts on this subject based on the ideXlab platform.
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Exoskeleton based on Counterbalance mechanism for arm strength assistance
Transactions of the Korean Society of Mechanical Engineers A, 2017Co-Authors: Won Bum Lee, Jae-bok SongAbstract:© 2017 The Korean Society of Mechanical Engineers. Workers in industrial fields are highly exposed to accidents or injuries caused by long working hours. An exoskeleton that is able to support the arm muscles of the worker and thereby reduce the probability of an accident and enhance working efficiency could be a solution to this problem. However, existing exoskeletons demand the use of high-priced sensors and motors, which makes them difficult to use in industrial fields. To solve this problem, we developed an arm assisting exoskeleton that consists only of mechanical components without any electronic sensors or motors. The exoskeleton follows the movement of the human arm by shoulder joint and ankle joint. In addition, Counterbalance mechanisms are installed on the exoskeleton to support arm strength. The experimental validation of the exoskeleton was conducted using an EMG sensor, confirming the performance of the exoskeleton.
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IROS - Reduction in gravitational torques of an industrial robot equipped with 2 DOF passive Counterbalance mechanisms
2016 IEEE RSJ International Conference on Intelligent Robots and Systems (IROS), 2016Co-Authors: Jae-bok SongAbstract:In most 6 DOF robot arms, considerable amounts of gravitational torques due to the robot's own weight are applied to pitch joints of the robot, which causes most arms to use high capacity motors and speed reducers. A spring-based Counterbalance mechanism can compensate for this gravitational torque, thus leading to a significant reduction in the effect of gravity. However, a simple installation of Counterbalance mechanisms at each pitch joint does not work properly because the gravitational torque at each joint is dependent also on the other joints. To achieve multi-DOF counterbalancing, we propose a parallelogram linkage combined with dual Counterbalance mechanisms, each being composed of a slider-crank mechanism and springs. Simulations and experimental results showed that the Counterbalance robot arm based on the proposed Counterbalance mechanisms effectively reduced the torques required to support the robot mass, thus allowing the prospective use of much smaller motors and speed reducers than traditional industrial robots.
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Reduction in gravitational torques of an industrial robot equipped with 2 DOF passive Counterbalance mechanisms
2016 IEEE RSJ International Conference on Intelligent Robots and Systems (IROS), 2016Co-Authors: Jae-bok SongAbstract:In most 6 DOF robot arms, considerable amounts of gravitational torques due to the robot's own weight are applied to pitch joints of the robot, which causes most arms to use high capacity motors and speed reducers. A spring-based Counterbalance mechanism can compensate for this gravitational torque, thus leading to a significant reduction in the effect of gravity. However, a simple installation of Counterbalance mechanisms at each pitch joint does not work properly because the gravitational torque at each joint is dependent also on the other joints. To achieve multi-DOF counterbalancing, we propose a parallelogram linkage combined with dual Counterbalance mechanisms, each being composed of a slider-crank mechanism and springs. Simulations and experimental results showed that the Counterbalance robot arm based on the proposed Counterbalance mechanisms effectively reduced the torques required to support the robot mass, thus allowing the prospective use of much smaller motors and speed reducers than traditional industrial robots.
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Multiple-Degree-of-Freedom Counterbalance Robot Arm Based on Slider-Crank Mechanism and Bevel Gear Units
IEEE Transactions on Robotics, 2016Co-Authors: Jae-bok SongAbstract:Low-cost but high-performance robot arms are required for robot arms to come into widespread use. To provide sufficient torques to support the robot mass and payload, most arms use expensive motors and speed reducers, which are the main reasons for their high price. As a solution to these problems, a multiple-degree-of-freedom (DOF) Counterbalance mechanism and robot arm were developed in our previous study, which can compensate for the gravitational torque due to the robot mass. However, there are durability and reliability problems associated with wire-based mechanisms. To solve these, in this study, we proposed a new Counterbalance mechanism based on a spring and slider-crank mechanism, along with a double-parallelogram mechanism composed of bevel gear units. Moreover, a 6-DOF Counterbalance robot arm was built to verify the performance of the proposed mechanism. Simulation and experimental results showed that the proposed mechanism effectively decreased the torque required to support the robot mass, thus allowing the prospective use of low-cost motors and speed reducers for high-performance robots.
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manipulator equipped with Counterbalance mechanism based on gear unit
Transactions of The Korean Society of Mechanical Engineers A, 2014Co-Authors: In Ho Kang, Jae-bok Song, In Sung ChangAbstract:로봇 머니퓰레이터는 사용 목적 및 관절의 구성에 따라 다양한 형태로 개발된다. 특히, 수직 다관절형 머니퓰레이터는 다른 형태의 머니퓰레이터에 비해 작업공간이 넓고, 활용성이 우수하여 다양한 분야에 적용되고 있다. 반면에, 작업을 위한 정지 및 이동 시에 로봇의 자중으로 인하여 각 관절에 큰 중력토크가 인가되어, 이를 부담할 수 있는 높은 용량의 감속기 및 모터를 필요로 한다. 그러나 이러한 고사양의 구성요소는 로봇의 제조단가를 향상시키는 주요 원인일 뿐만 아니라, 충돌 안전을 저해하는 원인이 되므로 사용되는 모터 및 감속기의 용량을 최소화하는 것이 바람직하다. 이를 위해서는 머니퓰레이터의 기존 성능을 유지하는 동시에 중력을 보상하는 데 필요한 토크를 낮출 수 있는 방법이 필요하다. 일반적으로 대용Key Words: Industrial Manipulator(산업용 로봇)Gravity Compensation(중력보상), Counterbalance Mechanism(중력보상장치) 초록: 일반적으로 산업용 로봇은 가반중량에 비해서 매우 큰 자중을 가지게 되며, 이로 인한 큰 중력토크를 보상하여야 하므로, 고사양의 모터/감속기를 사용하게 되어 제조단가가 높아진다. 이러한 머니퓰레이터의 자중 및 가반중량을 기계식 중력보상장치로 보상하게 된다면, 모터/감속기 사양을 크게 낮추어서 제조단가를 낮출 수 있다. 그러나 기존의 와이어 기반의 중력보상장치의 경우, 내구성 및 파손 등의 문제로 실용성이 낮았다. 본 연구에서는 이를 개선하고자 기어 및 롤러 기반의 내구성 높은 중력보상장치를 개발하고, 이를 사용하여 낮은 용량의 모터/감속기로도 가반하중 목표를 만족시킬 수 있는 중력보상장치를 탑재한 머니퓰레이터를 개발하였다. 본 연구에서는 다양한 시뮬레이션 및 실험을 통하여 제안한 중력보상장치가 머니퓰레이터의 모든 자세에 대해서 중력에 대한 완전한 보상토크를 제공하였으며, 큰 가반하중에 대해서도 적절한 보상토크를 제공할 수 있음을 보였다. Abstract: Industrial manipulators are usually heavy given the payloads they carry. Therefore, they require high-capacity servomotors and speed reducers, which leads to high costs. However, if manipulator weight could be compensated for using a Counterbalance mechanism, the motors' and speed reducers' capacities could be minimized substantially. However, it is usually difficult to assure durability and reliability with the conventional wire-based Counterbalance mechanism. Therefore, a more robust gear- and roller-based Counterbalance mechanism is proposed in this study. A manipulator was developed using this mechanism; this manipulator maintains its performance even when using motors and reducers of lower capacities. The results of various simulations and experiments verified that the proposed mechanism provides the torque required to compensate for gravitational torque in any configuration and minimizes the torque required for supporting a large payload.
Allan S. Detsky - One of the best experts on this subject based on the ideXlab platform.
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Preprints: a Timely Counterbalance for Big Data–Driven Research
Journal of General Internal Medicine, 2020Co-Authors: Amol A. Verma, Allan S. DetskyAbstract:Big data promises to spark new discoveries but may also distort clinical research. Large datasets that permit numerous analyses could increase the number of spurious findings and threaten the reproducibility and validity of clinical research. The publication of unreproducible research is incentivized by a scientific culture that rewards novelty over rigor. Introducing preprint publication to clinical research could change the culture. The first clinical preprint platform, medRxiv, allows researchers to publish working papers in advance of peer-review to more easily share preliminary findings. Preprint publishing aims to be fast and frictionless, which fundamentally changes the incentive structure of academic publishing . Preprints offer a relatively weak reward (a preprint publication) for substantially less effort than peer-review publication. By reducing barriers to publication, preprints may help encourage scientists to publish null findings, which could mitigate publication bias. By enabling scientists to share preliminary work and publish evolving versions of manuscripts, preprints may also facilitate “workshopping” of ideas and detailed methodological review. This would better reflect the iterative nature of observational research than peer-reviewed publications, which immutably document the “final” results of a study. Preprint platforms are a timely innovation that may buffer the undesired effects of big data on clinical research.
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preprints a timely Counterbalance for big data driven research
Journal of General Internal Medicine, 2020Co-Authors: Amol A. Verma, Allan S. DetskyAbstract:Big data promises to spark new discoveries but may also distort clinical research. Large datasets that permit numerous analyses could increase the number of spurious findings and threaten the reproducibility and validity of clinical research. The publication of unreproducible research is incentivized by a scientific culture that rewards novelty over rigor. Introducing preprint publication to clinical research could change the culture. The first clinical preprint platform, medRxiv, allows researchers to publish working papers in advance of peer-review to more easily share preliminary findings. Preprint publishing aims to be fast and frictionless, which fundamentally changes the incentive structure of academic publishing. Preprints offer a relatively weak reward (a preprint publication) for substantially less effort than peer-review publication. By reducing barriers to publication, preprints may help encourage scientists to publish null findings, which could mitigate publication bias. By enabling scientists to share preliminary work and publish evolving versions of manuscripts, preprints may also facilitate “workshopping” of ideas and detailed methodological review. This would better reflect the iterative nature of observational research than peer-reviewed publications, which immutably document the “final” results of a study. Preprint platforms are a timely innovation that may buffer the undesired effects of big data on clinical research.
Amol A. Verma - One of the best experts on this subject based on the ideXlab platform.
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Preprints: a Timely Counterbalance for Big Data–Driven Research
Journal of General Internal Medicine, 2020Co-Authors: Amol A. Verma, Allan S. DetskyAbstract:Big data promises to spark new discoveries but may also distort clinical research. Large datasets that permit numerous analyses could increase the number of spurious findings and threaten the reproducibility and validity of clinical research. The publication of unreproducible research is incentivized by a scientific culture that rewards novelty over rigor. Introducing preprint publication to clinical research could change the culture. The first clinical preprint platform, medRxiv, allows researchers to publish working papers in advance of peer-review to more easily share preliminary findings. Preprint publishing aims to be fast and frictionless, which fundamentally changes the incentive structure of academic publishing . Preprints offer a relatively weak reward (a preprint publication) for substantially less effort than peer-review publication. By reducing barriers to publication, preprints may help encourage scientists to publish null findings, which could mitigate publication bias. By enabling scientists to share preliminary work and publish evolving versions of manuscripts, preprints may also facilitate “workshopping” of ideas and detailed methodological review. This would better reflect the iterative nature of observational research than peer-reviewed publications, which immutably document the “final” results of a study. Preprint platforms are a timely innovation that may buffer the undesired effects of big data on clinical research.
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preprints a timely Counterbalance for big data driven research
Journal of General Internal Medicine, 2020Co-Authors: Amol A. Verma, Allan S. DetskyAbstract:Big data promises to spark new discoveries but may also distort clinical research. Large datasets that permit numerous analyses could increase the number of spurious findings and threaten the reproducibility and validity of clinical research. The publication of unreproducible research is incentivized by a scientific culture that rewards novelty over rigor. Introducing preprint publication to clinical research could change the culture. The first clinical preprint platform, medRxiv, allows researchers to publish working papers in advance of peer-review to more easily share preliminary findings. Preprint publishing aims to be fast and frictionless, which fundamentally changes the incentive structure of academic publishing. Preprints offer a relatively weak reward (a preprint publication) for substantially less effort than peer-review publication. By reducing barriers to publication, preprints may help encourage scientists to publish null findings, which could mitigate publication bias. By enabling scientists to share preliminary work and publish evolving versions of manuscripts, preprints may also facilitate “workshopping” of ideas and detailed methodological review. This would better reflect the iterative nature of observational research than peer-reviewed publications, which immutably document the “final” results of a study. Preprint platforms are a timely innovation that may buffer the undesired effects of big data on clinical research.
Jessica K. Hodgins - One of the best experts on this subject based on the ideXlab platform.
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ICRA - A passively safe and gravity-Counterbalanced anthropomorphic robot arm
2014 IEEE International Conference on Robotics and Automation (ICRA), 2014Co-Authors: John P. Whitney, Jessica K. HodginsAbstract:When designing a robot for human-safety during direct physical interaction, one approach is to size the robot’s actuators to be physically incapable of exerting damaging impulses, even during a controller failure. Merely lifting the arms against their own weight may consume the entire available torque budget, preventing the rapid and expressive movement required for anthropomorphic robots. To mitigate this problem, gravity-counterbalancing of the arms is a common tactic; however, most designs adopt a shoulder singularity configuration which, while favorable for simple Counterbalance design, has a range of motion better suited for industrial robot arms. In this paper we present a shoulder design using a novel differential mechanism to Counterbalance the arm while preserving an anthropomorphically favorable singularity configuration and natural range-of-motion. Furthermore, because the motors driving the shoulder are completely grounded, Counterbalance masses or springs are easily placed away from the shoulder and low in the torso, improving mass distribution and balance. A robot arm using this design is constructed and evaluated for Counterbalance efficacy and backdrivability under closed-loop force control.
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A passively safe and gravity-Counterbalanced anthropomorphic robot arm
2014 IEEE International Conference on Robotics and Automation (ICRA), 2014Co-Authors: John P. Whitney, Jessica K. HodginsAbstract:When designing a robot for human-safety during direct physical interaction, one approach is to size the robot's actuators to be physically incapable of exerting damaging impulses, even during a controller failure. Merely lifting the arms against their own weight may consume the entire available torque budget, preventing the rapid and expressive movement required for anthropomorphic robots. To mitigate this problem, gravity-counterbalancing of the arms is a common tactic; however, most designs adopt a shoulder singularity configuration which, while favorable for simple Counterbalance design, has a range of motion better suited for industrial robot arms. In this paper we present a shoulder design using a novel differential mechanism to Counterbalance the arm while preserving an anthropomorphically favorable singularity configuration and natural range-of-motion. Furthermore, because the motors driving the shoulder are completely grounded, Counterbalance masses or springs are easily placed away from the shoulder and low in the torso, improving mass distribution and balance. A robot arm using this design is constructed and evaluated for Counterbalance efficacy and backdrivability under closed-loop force control.
Toshikatsu Koga - One of the best experts on this subject based on the ideXlab platform.
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Electron-electron coalescence and Counterbalance functions for atoms
Journal of Chemical Physics, 2020Co-Authors: Toshikatsu KogaAbstract:For many-electron atoms, spherically averaged electron–electron coalescence h0(R) and Counterbalance d0(u) functions are studied which, respectively, represent the probability densities that any electron pairs with zero interelectronic distance are located at a radius R from the nucleus and that any electron pairs with zero center-of-mass radius have a relative distance u. For the exact and Hartree–Fock (HF) wave functions, cusp relations h0′(0)/h0(0)=−4Z and d0′(0)/d0(0)=−2Z are derived theoretically, where the prime denotes the first derivative and Z is nuclear charge. At the Hartree–Fock limit level, both functions h0(R) and d0(u) are found to be monotonically decreasing with a single maximum at R=0 or u=0 for all the 102 atoms He through Lr. The long-range asymptotic behavior of the coalescence and Counterbalance functions is governed in general by the orbital energy of the highest occupied atomic orbital.
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Note on the electron–electron Counterbalance hole
Theoretical Chemistry Accounts, 2010Co-Authors: Toshikatsu Koga, Hisashi MatsuyamaAbstract:The electron–electron Counterbalance hole implies that two parallel spin electrons cannot be at opposite positions with respect to the spatial inversion center, if it exists. The hole is known to appear for any approximate and exact wave functions with an even inversion parity. We point out that for particular cases, the Counterbalance hole also appears when wave functions have an odd inversion parity and two electrons with anti-parallel spins are involved.
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on the electron electron Counterbalance hole
Journal of Chemical Physics, 2008Co-Authors: Toshikatsu Koga, Masahiro SekiyaAbstract:When a many-electron system has spatial inversion symmetry, the electron-electron Counterbalance hole implies that two electrons with parallel spins cannot be at opposite positions with respect to the inversion center, and its presence was pointed out in the literature [T. Koga, J. Chem. Phys. 108, 2515 (1998)] for any pairs of Hartree-Fock orbitals with the same inversion parity. We report here a generalized result that in all two-electron systems with spatial inversion symmetry, the electron-electron Counterbalance hole always exists for any approximate and exact wave functions with even inversion parity. The same is also true in momentum space. An extension of the hole to systems with three or more electrons is discussed.
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Electron-electron Counterbalance hole in Hartree–Fock theory
Journal of Chemical Physics, 1998Co-Authors: Toshikatsu KogaAbstract:The electronic extracule density E(R) and its spherical average d(R) are probability densities of finding the center-of-mass vector (rj+rk)/2 and its magnitude |rj+rk|/2 of any two electrons j and k to be R and R, respectively. Theoretical analysis of spin–orbital-pair contributions Ejk(R) and djk(R) to the extracule densities shows that within the Hartree–Fock framework, there exists an “electron-electron Counterbalance hole” Ejk(0)=djk(0)=0 between two electrons in spin–orbitals j and k with the same spin and the same spatial inversion symmetry, which implies that the center-of-mass vector (or distance) of these electrons cannot be zero or these electrons cannot be exactly at the opposite positions in space with respect to the inversion center. The same is also true in momentum space. The electron-electron Counterbalance hole may be considered as a complement to the familiar electron-electron coalescence or Fermi hole for two electrons with the same spin. We also point out that the electron-electron cou...
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Electron–electron coalescence and Counterbalance densities for atoms in Hartree–Fock theory
Journal of Chemical Physics, 1997Co-Authors: Toshikatsu Koga, Hisashi MatsuyamaAbstract:The electron–electron coalescence I(0) and Counterbalance E(0) densities are probability densities of finding any two electrons, respectively, at the same position and at the reflection points in the three-dimensional space. For a single Slater determinant wave function, these electron-pair properties are shown to be exactly expressible in terms of the spin-traced one-electron density function ρ(r) and its orbital components ρi(r): I(0)=(1/4){〈ρ〉−ΔI} and E(0)=2{〈ρ〉−ΔE}, where 〈ρ〉 is the average electron density, and ΔI and ΔE are linear combinations of overlaps between two orbital densities, that depend on the electronic configuration and the LS multiplet state of the atom under consideration. For the atoms He through Ne in their experimental ground state, the explicit forms of ΔI and ΔE are derived, and the electron–electron coalescence and Counterbalance densities obtained from the numerical Hartree–Fock calculations are discussed.
