Abstract The increased demand for performing crane ship modeling has led to the necessity for fast and accurate numerical experiments. This paper presents an approach for creating a numerical model of a crane vessel with a suspended load that allows for real-time control of crane parts. The model is developed in the MATLAB/Simulink environment, which makes it possible to extend it further to the user's needs. The authors describe the approach to the calculation of wave-induced ship motions, presents the Simulink block model and describes the features encountered during the simulation process. The possibility of real-time control of the position of crane parts is also shown, keeping the calculation speed of the ship hydrodynamics.

In recent years, different types of commercial rollators or gait-training devices have been widely used by elderly people, suffering from dementia, for their daily activities to avoid being bedridden. However, the effectiveness of most of these commercial devices has not been investigated thoroughly. In this study, a novel rollator with a freely rotating chest pad, integrated with two angular sensors and two load cells, was developed. Walk measurements were carried out on four young healthy subjects who performed walk tests using the developed rollator. To measure the motion of the lower limbs, two goniometers were attached to the exteriors of both the knees, and two more were attached to the exteriors of both the ankle joints of the subjects. The results of the pressing forces on the pad measured by the load cells, pad rotations, knee extensions, and ankle rotations were demonstrated. Frequency analyses were performed and correlation coefficients were computed for the obtained results. The relationship between the pad rotation and the motion of the lower limbs was investigated, and the effectiveness of the developed novel rollator in walk assistance was discussed.

A novel plastic injection mold design for a product with a deep arc-hole based on the kinematic analysis is proposed. To move the wide angle arc-core, a hybrid mechanism combining a slider-crank and a swing cam is designed. The force transmission coefficient of the slider-crank and the pressure angle of the swing cam are used to evaluate the dimensions of the mechanism. The motion of the designed mechanism was confirmed by using a prototype made with a 3D printer.

[Purpose] Discrimination between end-feel types is difficult, and years of clinical experience is considered a factor for improving the accuracy of the discrimination. The present study investigated whether the accuracy of classification of end-feel types improves with the increase in years of clinical experience. [Participants and Methods] In total, 44 therapists (range of years of clinical experience: 1-26 years) and 13 students were included. The participants identified the type of end feel simulated by our newly developed simulator. The proportion of correct answers of the therapists was compared with that of the students. For the therapists, years of clinical experience and their awareness of end feel were examined, and their relationships with the ability to classify end-feel types were analyzed. [Results] The therapists showed a higher ability to identify end-feel type than the students. The ability of the therapists improved according to their years of clinical experience. The cutoff values for years of clinical experience to improve the ability for identifying bone-to-bone, muscular, and tissue approximations were 15, 6, and 15, respectively. The therapists who were always conscious about end feel were associated with a higher ability to classify end-feel types. [Conclusion] Our present study demonstrated that the ability to classify end feel improves with the increase in years of clinical experience.

Physical therapist (PT) emphasizes their haptic feedback during diagnosing patient symptoms. However, there is no standardized method to quantitatively assess PT's haptic sensation. In this paper, we report the difference of the haptic sensation between experts and novices using the end-feel training robot. The training robot is driven by the combination of the motor torque (controllable force) and the spring force (uncontrollable force). We employ three kinds of force protocol which imitates human end-feel reaction force. In the subjective experiment, the PTs are presented the reaction forces from the training robot and answered the most similar end-feel. We divide the PTs into two groups based on the similarity score using K-means++. The PTs are clearly classified into the high score group and the low score group. Depending on to the questionnaire, the PTs in the high score group worked long years and treated motor system disease patients mainly. This result indicates that our scoring method utilizing the training robot can evaluate the PT's haptic sensation quantitatively.

Parallel robot has excellent characteristics such as high speed, high precision and high rigidity. However, mechanical collisions between limbs, and complexly existing singular configurations restrict its workspace. In this paper, firstly, methods for expanding the translational workspace of the parallel robot are discussed. Parallel robot has multiple solutions of the inverse and forward kinematics. By changing its configurations from one solution to another, the parallel robot can expand its translational workspace. However, conventional non-redundant parallel robot encounters singularity during the mode change. Singularity free mode changes of the parallel robot by redundant actuation and asymmetrical design are introduced. Next, methods for expanding the rotational workspace of the parallel robot are shown. In order to achieve the large rotation, mechanical gimmicks by gears, pulleys, and helical joints have been embedded in the moving part. A differential screw-nut mechanism for expanding the rotational workspace of the parallel robot is introduced.

A novel 6 dof 8 cable-driven parallel robot (CDPR) is proposed. The proposed robot is redundantly driven by 8 cables. By the rotational mechanism inside the moving part (MP), the proposed CDPR has two redundancy, kinematic redundancy and actuation redundancy. The kinematic redundancy contributes to avoiding collisions between cables, and the actuation redundancy is used for control the cables' tensions. The proposed CDPR has large workspace by avoiding the cables' collisions, and high precision by keeping the tensions of all cables as positive values. In this paper, control method for avoiding the cables' collisionsby the kinematic redundancy is discussed in detail. Copyright is held by the owner/author(s). Publication rights licensed to ACM.

A novel differential screw drive mechanisms for 2-dof (onerotational and one-translational) drive system is proposed in this paper. The proposed screw is named as Gaudi-inspired screw, because the shape of the screw is similar to the double helix columns by Antoni Gaudi. Kinematics, geometry, and prototyping the Gaudi-inspired screw is introduced in this paper. Firstly, kinematics about differential screw drive mechanism, including the Gaudi-inspired screw, is introduced. The Gaudi-inspired screw is overlapped helix of the right and left helix of a square. Geometrical characteristics and shapes of the cross sections of the screw are discussed in detail. Plans for making the screw and the nuts by 3D printing, cutting, form grinding, wire-cut EDM and die-sink EDM are introduced. The Gaudi-inspired screw and the nuts were prototyped by 3D printing and by cutting.

A novel parallel mechanism which enlarges the workspace by singularity-free mode changes is proposed. The proposed mechanism has inherited the design of Linear DELTA, three translational degree-of-freedom and the moving plate driven by three linear actuators. In addition, the mechanism is extended by redundant actuation by four linear actuators and asymmetric design. New criterions about redundancy and singularity of redundantly actuated parallel mechanism using summation and product of determinants of minor matrices of the transposed Jacobian matrix are proposed. Redundant actuation and asymmetric design enables singularity-free mode changes with loss redundancy but maintains non-singularity, which is evaluated by the proposed criterions. Numerical simulations demonstrate the singularity-free mode changes of the proposed mechanism.

A novel redundantly actuated parallel robot for mold polishing work is proposed. Cogging-less direct drive motors are implemented in the prototype. Instead of using conventional spherical sliding bearings, ball bearings with appropriate preload are implemented in the rolling pairs of the prototype. These mechanical parts enable fine force control for mold polishing work. The rated force of the robot perpendicular to the surface on the workpiece is 20 N with a tangential force of 5 N, which enable the robot to execute polishing tasks as well as skilled workers. In addition, the polishing velocity along the tangential direction is 60 m/min, which exceeds skilled workers' velocity of 10 m/min. High speed feed contributes to reducing the polishing force and improving the quality of the surface of the mold. Kinematics, statics, dynamics and control of redundantly actuated parallel robot are discussed in this paper. Impedance control was implemented to the prototype for stably executing the mold polishing work.

A novel parallel mechanism which enlarges the workspace by singularity-free mode change is proposed. The proposed mechanism is inherited the design of Linear DELTA which has three degree-of-freedom translational moving plate driven by three linear actuators, in addition, extended it by redundantly actuation by four linear actuators and asymmetric design. New criterions about redundancy and singularity of redundantly actuated parallel mechanism using summation and product of determinants of minor matrices of the transposed Jacobian matrix are proposed. Redundantly actuation and asymmetric design enables singularity-free mode changes with loss redundancy but maintain non-singularity, that are evaluated by the proposed criterions. Numerical simulations demonstrate the singularity-free mode changes of the proposed mechanism. © (2014) Trans Tech Publications, Switzerland.

A novel architecture for a parallel Schonflies motion generator was recently proposed, consisting of a CRRHHRRC linkage. The novelty of this architecture lies in its simplicity, as it comprises only two limbs, thereby forming a single-loop closed kinematic chain. Reported in this paper is a realization of this architecture, intended for the production of a proof-of-concept prototype. The realization includes an innovative actuator mechanism, which is based on two-degree-of-freedom cylindrical joints. Moreover, its moving plate is coupled to the two limbs by means of corresponding coaxial H pairs. The paper focuses on the kinematics and singularity analysis of this robot, intended for fast pick-and-place operations. The prototype is currently under development at McGill University's Centre for Intelligent Machines.

The quest for ever faster pick-and-place robots has led to ingenious parallel robots with reduced mobility, e.g., capable of producing motions proper of SCARA systems: three independent translations and one rotation about an axis of fixed direction. These robots are also known as Schonflies-motion generators (SMG). Some parallel versions are commercially available, as are serial-parallel designs. The former are provided with four limbs, the latter with three, the fourth degree of freedom being appended in series with a Delta robot. Parallel robots are more attractive than their hybrid counterparts, but the presence of four legs poses serious challenges to their designers, as limb-interference limits the rotatability of the moving plate. A solution to this problem includes a gear train for rotation-range amplification, but this increases the inertial load on the motors and complicates the design-too many parts-and the control-because of inherent gear backlash and Coulomb friction. Recently, a SMG system was proposed that is supplied with two limbs, arrayed in an isostatic structure, which provides high rotatability of its gripper. This robot is driven by one C (cylindrical)-joint at each limb. As this joint allows for two degrees of freedom, it calls for two motors, that might as well be fixed to the base, which poses interesting design challenges. Reported in this paper is a design solution for the drive of a C joint, which is termed the C (cylindrical)-drive, based on a cylindrical differential mechanism of the RHHR type, with R standing for revolute, H for helical (or screw) joint. The design, kinematics and dynamics of the drive are discussed, along with a realization, and preliminary tests.

A 3-dof active scanning probe using a translational parallel mechanism (TPM) is proposed. The TPM proposed in this study employs a small touching force control and can be used as a probing device for coordinate measurement, working within an area of a few cubic millimeters. In this paper, the characteristics of the mechanism, optimization of design, prototyping, and accuracy of the TPM are introduced. In the proposed optimization TPM design, the manipulability of the mechanism is equal in all directions. This implies that the positional sensitivities of the TPM share an isotropic relationship. The positional resolution of the mechanism becomes less than 1.0 μm in a cubic working range with side length of 1.6 mm. An experimental mechanism using the proposed design is introduced. In order to evaluate the accuracy of the TPM, we have developed an experimental system for the measurement of the position of the TPM using image processing. By applying mechanical parameters calibration, the accuracy of the absolute position of the TPM has been improved to 3.4 μm. © KSPE and Springer 2012.

A 3-dof active scanning probe using a translational parallel mechanism (TPM) is proposed. In this paper, the characteristics of the mechanism, optimum design, prototyping, and accuracy of the TPM are introduced. In the proposed optimum TPM design, the manipulability of the mechanism is equal in all directions. This implies that the positional sensitivities of the TPM share an isotropic relationship. The positional resolution of the mechanism becomes 0.58 μm in a cubic working range with side length of 1.6 mm. An experimental mechanism using the proposed design is introduced. Relationships between positioning errors and mechanical parameters of the TPM are revealed by applying the error propagation analysis. In order to evaluate the accuracy of the TPM, we have developed an experimental system for the measurement of the position of the TPM using image processing. By applying mechanical parameters calibration, the accuracy of the absolute position of the TPM has been improved to 3.4 μm. © 2012 The Japan Society of Mechanical Engineers.

A 3-dof active scanning probe using a translational parallel mechanism (TPM) is proposed. In this paper, the characteristics of the mechanism, optimum design, prototyping, and accuracy of the TPM are introduced. In the proposed optimum TPM design, the manipulability of the mechanism is equal in all directions. This implies that the positional sensitivities of the TPM share an isotropic relationship. The positional resolution of the mechanism becomes 0.58 μm in a cubic working range with side length of 1.6 mm. An experimental mechanism using the proposed design is introduced. In order to evaluate the accuracy of the TPM, we have developed an experimental system for the measurement of the position of the TPM using image processing. By applying mechanical parameters calibration, the accuracy of the absolute position of the TPM has been improved to 3.4 μm. © 2011 IEEE.

A redundantly actuated 3-degrees-of-freedom (xyθ) planar parallel mechanism with back-flip motion (PM BFM) is proposed. The back-flip motion means that the end plate of the parallel mechanism rotates more than 180 degrees. In this paper, firstly, mechanical features of the PM BFM are revealed. Secondly, a parallel drive system of linear motors is applied to the PM BFM. This parallel drive system is a driving method in which two linear motors on two stators are driven by a single servo amplifier. Features of the parallel drive system are revealed. Finally, the peculiar mechanical interference of the PM BFM is analyzed. © 2011 IEEE.

The impedance control of a 3-degree-of-freedom (DOF) xyθ planar parallel link mechanism (PLM) with four redundant actuators, i.e., a 3D4M PLM, is proposed. The impedance control requires forward kinematics, which gives the position and orientation of the end effector of the PLM. The notable link arrangement of the 3D4M PLM makes it easy to derive the forward kinematics, which have been difficult to derive for conventional parallel links. In addition, the relations of static forces, including the internal force through redundant actuation, are derived. Using the forward kinematics, formulas of the impedance control that take into consideration the internal force of the 3D4M PLM are derived. Based on the design of decoupled dynamics, an experimental system of the 3D4M PLM is developed. A PLM is constructed on linear motors in which four moving parts are individually driven on one stator part. Workspace impedance control achieved by force command is implemented in the experimental system using a digital signal processor (DSP) based real time controller. Experimental responses of free damped vibrations to impedance control are compared with corresponding theoretical responses. © 2010 IEEE.

Impedance control of a 3D4M parallel link mechanism (PLM), a 3 degree of freedom (xyθ) planar parallel link mechanism with redundant 4 actuators, is proposed. The impedance control requires the forward kinematics, which gives position and orientation of the end plate of parallel link mechanism. The notable link arrangement of the 3D4M PLM makes it easy to derive the forward kinematics, which have been difficult to derive the conventional parallel links. By using the forward kinematics, formulas of the impedance control of the 3D4M PLM were derived. Based on the previous report about the design of decoupled dynamics, experimental system of the 3D4M PLM was developed. A parallel link mechanism was constructed on linear motors in which 4 moving parts were individually driven on one stator part. Workspace impedance control achieved by force commands were implemented in the experimental system using a DSP based real time controller. Experimental responses of free vibrations to impedance control were compared with corresponding theoretical responses.

A robust measurement method for measuring the vertex position of a small polyhedron using 3D image processing is proposed. The shape from focus method is applied for obtaining 3D positions of surfaces of the polyhedron. The in-focus function is usually averaged for reducing noise, but the resultant function lacks sharp edge information of the target. The position of the vertex is indirectly calculated from 3D data using the geometrical model of the polyhedron. In this study, relationships between measurement noise and ( a) the appropriate number of data values required for averaging of focal measurement and (b) the area of data fitted by the Gaussian function are investigated. Then, error propagation analysis is applied to the equations of the indirect measurement of the vertex position. By using the geometrical characteristics of the polyhedron, the vertex position measurement is made robust against measurement errors. The effectiveness of the proposed method is confirmed by numerical simulations and experiments.

In this study, we developed parallel link mechanisms by using multi-drive linear motors. Kinematics, dynamics, and control method of a three-degree-of-freedom (xyθ) planar parallel link mechanism with four redundant moving parts (3D4M mechanism) were investigated. A prototype of the 3D4M mechanism, which has decoupled dynamic characteristics, was developed. A notable kinematic characteristic of this mechanism was observed: the forward kinematics equation can be easily obtained by this mechanism. Workspace impedance control achieved by a force command was implemented in the prototype using a DSP based real time controller. Experimental responses of free vibrations to impedance control were compared with corresponding theoretical responses.

In this paper, parallel link mechanisms for multi drive linear motors (MDLMs) are proposed. The multi drive is a control method for linear motors in which a number of moving parts are individually driven on one stator part. Various configurations of parallel link mechanisms which were constructed for MDLMs are proposed. These mechanisms offer a wide range of motion in addition to the existing characteristics that parallel mechanisms provide, namely, rigid mechanisms, high precision, and high speed. Moreover, they are suitable for force control because of their low friction direct drive actuators. In this paper, the kinematic and dynamic characteristics of 2-DOF (xy) and 3-DOF (xy theta) planar parallel link mechanisms are investigated. A singularity analysis and internal force control method for a 3-DOF with 4 redundant moving parts is derived. The condition of dynamic decoupling and the constant inertia design of a 2-DOF with 2 moving parts and a 3-DOF with 4 moving parts are derived. The effectiveness of these analyses is then confirmed by numerical simulation. Based on this analysis, a prototype of the 3-DOF with 4 moving parts is designed and developed.

Parallel link mechanisms with multi drive linear motors (MDLMs) were proposed. The multi drive is a control method of linear motors that multi moving parts are individually driven on one stator part. Various configurations of parallel link mechanisms were constructed on the MDLMs were proposed. The proposed mechanisms have additional features of wide moving area in addition to the original characteristics of the parallel mechanisms such as rigid mechanisms, high precision and high speed. More over, they are suitable for force control because of low friction direct drive actuators. In this paper, kinematics and dynamics characteristics of 2-DOF (xy) and 3-DOF (xyθ) planar parallel link mechanisms were investigated. Singularity analysis and internal force control method of the 3-DOF with 4 moving parts redundant mechanism were derived. Condition of a dynamics decoupling and constant inertia design of the 2-DOF with 2 moving parts and 3-DOF with 4 moving parts were derived. Effectiveness of those analyses was confirmed by numerical simulation. Basic on the analysis, prototype of the 3-DOF with 4 moving parts parallel link mechanism was designed and developed.

A robust measurement method for vertex position of a small polyhedron using 3D image procession is proposed. Shape from focus method is applied for getting 3D positions on surfaces of the polyhedron. Averaging of in-focus function is usually applied for reducing noises, but it lacks sharp edge information of the target. The position of the vertex is indirectory calculated from the 3D data using geometrical model of the polyhedron. In this paper, relations between measurement noise and appropriate number of data for averaging of focal measurement, and area of data for fitting of the Gaussian function were investigated. Then, error propagation analysis is applied to the equations of the indirect measurement of the vertex position. By using the geometrical characteristics of the polyhedron; measurement of the vertex position became robust against the measurement errors. Effectiveness of the proposed method was confirmed by numerical simulation and experimental result for measurement of a vertex of a small polyhedron.

A robust measurement method for vertex position of a small polyhedron using 3D image procession is proposed. Shape from focus method is applied for getting 3D positions on surfaces of the polyhedron. Averaging of in-focus function is usually applied for reducing noises, but it lacks sharp edge information of the target. The position of the vertex is indirectory calculated from the 3 D data using geometrical model of the polyhedron. In this paper, relations between measurement noise and appropriate number of data for averaging of focal measurement, and area of data for fitting of the Gaussian function were investigated. Then, Error propagation analysis is applied to the equations of the indirect measurement of the vertex position. By using the geometrical characteristic of the polyhedron, measurement of the vertex position became robust against the measurement errors. Effectiveness of the proposed method was confirmed by numerical simulation and experimental result for measurement of a vertex of a small polyhedron.

The extremely precise level of cutting work's demand has been increasing, recently. Therefore, the establishment of a supreme measurement technology for micro endmills during operating on ultra-precision machining center plays an important role in many micro fabrication industries. The "Diffraction Gauge Method", a novel measuring technique based on far field laser diffraction, has been proposed to measure cutting edge profiles of micro tools (φ<500μm) with repeatability of better than 100 nm even though on machine surroundings. In this paper, cutting edge profile measurement of worn micro endmills (φ300μm), which operated side milling on graphite work material, is carried out. Agreement of the measured profiles with SEM image confirms the high accuracy of the measurement technique. Subsequently, the tool wear evaluations in various cutting lengths of micro endmills before and after cutting notify the relationship between increase in tool wears and cutting length. These experimental results verify the validity of our novel micro endmill measurement technique, which can be applied into ultra-precision machining center in the near future.

The Diffraction Gauge Method, a novel measuring technique based on far-field laser diffraction, has been proposed to measure cutting-edge profiles of micro cutting tools with repeatability of better than 100nm even though on-machine surroundings. In this article, the cutting-edge profile measurements of worn micro endmills (φ300μm) are carried out. Agreement of the tool cutting-edge profiles measured by our method with the image observed by SEM certifies the accuracy of the measurement technique. Furthermore, the automated measurement on the tools is demonstrated for a purpose of duplicating on-machine measurement. Then, wear growth on micro tools are also investigated. The measurement results suggest that the method is available to evaluate the micro tool cutting-edge profiles as an ultra precision on-machine measurement.

A new optical measuring method of cutting edge profiles with a few nanometerresolutions for micro milling tool is proposed. The edge profile is scaled by the width between the first order maxima in a diffraction pattern, which relates to the spacing of a slit-type aperture formed between a reference knife-edge and a tool cutting-edge. The technique is applicable for on-machine measurement due to simplicity and long working distance of the optical system. In this paper, first, the theoretical analysis reveals the measurement resolution, and then the proposal of laser diffraction gauge method is mentioned. Next, the calibratability and the practicability of our technique are affirmed with fundamental experiments. Furthermore, experimental verifications are carried out for commercial tools such as straight-flute and helical-flute of micro endmills. Subsequently, excellent agreement of the profiles, which are measured with our developed experimental systems, with an image from scanning ion microscope verifies that the proposed method is efficient to accurately measure cutting-edge profiles.

A new optical measuring method of edge profiles with a few nanometer resolution for micro cutting tool is proposed. The edge profiles are scaled by the measurable width between the first two maxima in diffraction patterns, which relate to the width of a slit-type aperture formed between a reference knife-edge and a tool cutting-edge. This technique is applicable for on-machine measurement due to simplicity and long working distance of the optical system. In this paper, first, the theoretical analysis reveals the measurement resolution. Next, the scalability and the practicability of the method are affirmed by the fundamental experiments. Furthermore, the experimental verifications are carried out for practical tools such as straight and helical flute cutting tools. Subsequently, good agreement of profiles measured by developed experimental apparatus with a scanning ion microscope image verifies that the proposed method is efficient to accurately measure cutting-edge profiles.

Error estimation and compensation algorithm for tooth form grinding works of a helical gear is proposed. Tooth profile ground by a formed wheel is modeled by truing parameters and setting parameters of the grinding wheel. Actual tooth form is measured by a touch probe on the machine. The truing and setting parameters are estimated by fitting the modeled surface to the measurement data as the distances between the modeled surface and the measurement points coincide with the probe radius. Error propagation analysis from measurement errors to the estimation errors of the parameters is applied and suggests robust measurement algorithm. The proposed method was applied to the actual grinding process. The truing and setting errors were measured and compensated within 10 micrometers.

Robust error compensation algorithm for tooth furor grinding works of an involute spur gear is proposed. The proposed algorithm is insensitive for the measurement error of the tooth form profile data. Relationship between indirect measurement quantity; the grinding error and direct measurement quantity; the tooth profile data are expressed by an implicit function. Error propagation analysis for the implicit model is derived using implicit derivative of the model function. Error ellipsoid of the indirect measurement quantity, which expresses the projection of the error hyper sphere of the direct measurement quantity, is defined. By taking the structural restrictions of the grinding error model into the least square calculation of the error estimation, the primary axis length of the error ellipsoid became smaller, which means the algorithm became more insensitive fur the measuring error. Proposed algorithm was implemented on an in-process measuring system with personal computer. Accurate grinding error compensation was confirmed by experimental results.

An error compensation method for tooth form grinding works of an involute helical gear is proposed. Not only setting errors of a grinding wheel but also truing errors of it are concerned into the machining model. Profiles of tooth form are measured by a touch sensor, which is attached on the NC grinding machine. Distance between the profile data and tooth surface is expressed by nonlinear equations with constraints of implicit functions. The truing error and the setting error of the grinding wheel are derived as the distance between the actual tooth form profile data and the model tooth surface equal to the probe radius. Jacobian matrix, which is used in least square calculation for the error estimation, is derived by applying higher order differentials of the nonlinear equations and the implicit functions. The proposed algorithm was confirmed by numerical simulation. © 1999, The Japan Society of Mechanical Engineers. All rights reserved.

Robust error compensation algorithm for tooth form grinding works of an involute spur gear is proposed. The proposed algorithm is insensitive for the measuring error of the tooth form profile data. Relationship between indirect measuring quantity the grinding error and direct measuring quantity the tooth profile data are expressed by an implicit function. Error propagation analysis for the implicit model is derived using implicit derivative of the model function. Error ellipsoid of the indirect measuring quantity which express the projection of the error hyper sphere of the direct measuring quantity is defined. By taking the structural restrictions of the grinding error model into the least square calculation of the error estimation, the primary axis length of the error ellipsoid became smaller, which means the algorithm became more insensitive for the measuring error. Proposed algorithm was implemented on a in-process measuring system with personal computer. Accurate grinding error compensation was confirmed by experimental results. © 1999, The Japan Society of Mechanical Engineers. All rights reserved.

An error compensation method for tooth form grinding works of an involute spur gear using a grinding wheel formed on the machine is proposed. Coordinate systems are set on the tooth form and workpiece. Forming and positioning error of the grinding wheel cause the position and orientation error of these coordinate systems, while keeping the figure of the tooth form involute curves. Profiles of tooth form and workpiece are measured by a touch sensor which is attached on the NC grinding machine. Nominal curve of the tooth form and the workpiece are fitted on the probed data using least square curve matching. Difference between the nominal and the actual relations of these coordinates is compensated as forming error of the grinding wheel and grinding positioning error. The proposed algorithm was confirmed by numerical simulation.

As the motor which drives a robot arm produces d torque ripple effect, the resulting resonance vibration in the robot arm impedes the robot's high locus precision. To counteract this problem, using software servo, a correction signal which cancels the torque ripple is fed into the system, and this eliminates resonance vibration. The method for this procedure is presented in this paper. For the derivation of this correction signal, the theory for single-plane balancing of rotor vibration may be applied, which makes it possible to derive the correction signal accurately and systematically. Experimental testing in which this technique was applied to a robot of one degree of freedom was performed. The experimental results adequately verified the effectiveness of this technique.

本研究は平面3自由度冗長駆動パラレルメカニズムの姿勢遷移による動作領域の拡張を目的とし，冗長駆動に特化した姿勢遷移方法を提案することを目標とする複数の順運動学解間の姿勢遷移(アセンブリモード変化)である逆折れ動作に対して，姿勢遷移中の特異姿勢を回避する方法を提案する．はじめに，PRRRPサブメカニズムの機構特性を利用して，順逆運動学解の導出と姿勢遷移の状態定義を行う．次に，冗長駆動パラレルメカニズムの特異姿勢解析を2-PRRRPメカニズムへ適用し，逆折れ動作中の特異姿勢を回避する姿勢遷移方法を提案する．実験装置にて，提案した姿勢遷移方法を実現する結果を示す．

基礎ゼミ２で行っている2足歩行ロボットを用いた教育プログラムについて発表を行った。

2021年度は，『極小径超長リード差動ネジ機構を搭載する広可動域ミニチュアパラレルロボットの開発』のブレークスルーとなる，軸径(D)1mm～2mm以下，進み角60度程以上，ネジ長さL/D=20(ネジ長さLが軸径Dの20倍)以上の極小径・超長リード・大アスペクト比差動ネジ機構の開発に取り組んだ． 差動ネジ機構は，ネジ部とナット部で構成される．我々は軸直角断面が正方形の左右ネジのオーバーラップ形状であるネジを用いた2入力2出力の差動駆動機構を提案し，そのネジ形状は建築家Gaudiの設計様式である二重らせん構造に類似しているためにGaudiネジと命名している．Gaudiネジのネジ面の曲率半径は一般的なネジ溝と比較して大きいために，半径の大きいボールエンドミルを用いた切削加工が可能であり，小径化かつ長リード化に適している．小径大アスペクト比の機械部品の切削加工時のたわみを抑制するために，先端部から根元部にかけて荒加工と仕上加工を段階的に行う工法を着想し，高精度5軸マシニングセンタを用いてアルミ合金を切削加工し，正方形断面の1辺2mm，進み角58度，全長40mm(L/D=20)のミニチュアGaudiネジの実加工に成功した．本研究成果に関して，日本機械学会 2021年度年次大会(2021年9月)で講演を行った． また，上記ネジにかみ合う正方形断面の1辺が2mmの右，左ナットの開発を実施した．正方形断面のねじれ溝に沿ってナットを4分割加工して組み合わせる工法を着想し，高精度5軸マシニングセンタを用いてアルミ合金を切削加工した．分割ナットを組込むハウジングは別途光造形3Dプリンタを用いて製造した，製造したナットは上記ミニチュアGaudiネジと組み合わせて差動ネジ機構として動作しうることを検証した．本研究成果に関して，日本機械学会 機素潤滑設計部門講演会 (2021年12月)にて講演を行った．

上肢リハビリ支援システムの本格的実用化を目指している。 差動ループベルトと差動ネジを組み合わせた新しい４自由度直交型パラレル機構を提案してきた。これまでは，数式計算ソフトウエアを用いて、動力学と拘束条件の混合微分方程式であるマルチボディシステム動力学を応用して、提案したロボットシステムの運動方程式を数式的に導出した．2021年度は，マルチボディダイナミクス用数値計算ソフトウエアの一つであるSimscape Multibodyを用いて提案する機構の動的解析を行った。 高価で 大きなリハビリ支援システムは、一部で使用されているが、本格的な 実用化には至っていない。リハビリ専門病院を除くと、一般病院・医院、老健施設、介護施設等は、大きく高価な装置の導入は困難である。また、上肢リハビリ支援システム以外に、多種の装置を置く必要があるため、小型で収容性の良いシステムが望まれる。そこで、回転 plus リニア型システム、およびリニア型システムの開発を行った。 リンク型の力覚提示システム・位置入力システムやリハビリ支援システム等の設計においては、慣性力の影響を考慮する必要がある。そこで、力学モデルによる理論解析を行い、数値計算を行い、評価方法を提案した。次に、特性改善方法を提案し、閉リンクモデルが優れていることを示した。 次に、閉リンクモデルの実験装置を作成し、予備実験を行った。実験では、特性の改善が見られ、ヒューマンインターフェイスとして優れていることが分かった。

A cable-driven parallel robot controls the position and orientation of its moving part by changing the length of multiple cables connected to the moving part. This type of robot has excellent characteristics of fast movement of the low weight moving part and the wide translational operating range by using a long cable. It is used for moving stadium cameras, etc. However, there is a problem that the cables interfere with each other when the movable part is rotated, and the rotational operating range is limited. In this research, we proposed a new robot that realizes infinite rotation of the rotary pulley embedded in the moving part and frictionally driving the pulley using an endless cable, and designed it based on mechanical analysis. The method was established and verified by numerical calculation and basic experiments.

A novel two-limb six-degrees-of-freedom (dof) parallel robot redundantly driven by eight actuators is proposed. The mechanism of the robot has a two-layer structure in which the eight-dof actuators control the six-dof hand via the seven-dof internal mechanism. The first part of the hierarchy from the eight-dof actuators to the seven-dof internal mechanism has actuation redundancy, and the second part of the hierarchy from the seven-dof internal mechanism to the six-dof hand has kinematic redundancy. The kinematic redundancy contributes to singularity avoidance, while the actuation redundancy contributes to backlash removal by acting on the internal forces of the mechanism. The validity was verified by numerical calculations and the prototyping. A novel differential screw drive systems and differential belt drive systems are also developed as related researches of this project.

About 30% of the cause becoming bedridden is the cerebro-vascular diseases such as strokes. At present, it is a little time to be used for rehabilitation training in one day. Therefore, the semiautomating training using robotics technology is preferable for long time training. Most of the rehabilitation training robots are active type using motors. Furusho of the study representative has been conducted the study on rehabilitation training systems for upper extremities having the safety that were low cost and were safer to present force sense with brakes. In this study, new non-active type rehabilitation training systems are developed. Moreover, the basic consideration about the rehabilitation training combining the developed rehabilitation systems with various rehabilitation training technique was executed.

A novel parallel mechanism which enlarges the workspace by singularity-free mode change is proposed. The proposed mechanism is inherited the design of Linear DELTA which has three degree-of-freedom translational moving plate driven by three linear actuators, in addition, extended it by redundantly actuation by four linear actuators and asymmetric design. New criterions about redundancy and singularity of redundantly actuated parallel mechanism using summation and product of determinants of minor matrices of the transposed Jacobian matrix are proposed. Redundantly actuation and asymmetric design enables singularity-free mode changes with loss redundancy but maintain non-singularity, that are evaluated by the proposed criterions. Numerical simulations demonstrate the singularity-free mode changes of the proposed mechanism. The singularities avoided mode changes were performed by newly developed prototype.

The percentage of aged persons in society and their number are increasing, and their physical deterioration has become a social problem in many countries. Early detection of function deterioration and sufficient rehabilitation training are necessary, not only to decrease the numbers of aged who are bedridden or need nursing care, but also to enable the aged to take an active part in society. So, we studied and developed rehabilitation systems for upper limbs using nano-particle MR fluid actuators. In this system, MR actuators were used for the purpose of securing high safety. The rheological properties of MR fluids are rapidly and reversibly altered under an applied magnetic field. We also studied facilitation systems by vibration using vibration actuator and MR fluidbrake. Moreover, we studied the evaluation device of synergy movement in stroke patients.

A 3-dof active scanning probes using non-redundantly and redundantly actuated translational parallel mechanisms are developed. In order to improve the positioning accuracy and controlling small forces, a small parallelogram linkage with low friction joint is developed. We have developed 3D measurement system by stereo cameras for evaluating the accuracy of the parallel mechanisms. The positional resolution of the redundantly actuated mechanism becomes 0.5μm in a cubic working range with side length of 1.6 mm. By applying mechanical parameters calibration, the accuracy of the absolute position of the parallel mechanism has been improved to 2.4μm. A stable scanning motion based on the impedance control is also developed.