The development competition by each team is getting yearly more and more acute in Formula 1 in late years. While the engine power continues to increase, good progress of the gearbox is being made toward being lighter in weight and smaller in size in every year. This paper describes the technology trend of recent F1 gearbox and some parts of the development in Honda

View full abstract

Bottom up fabrication technology is very important for creating nano-mechanism. Usually, self assembling features of molecules using physical and chemical principle are used, and biopolymer is one of the promising materials for the nano-mechanism. Among many kinds of biopolymers, DNA has special features such as 1)base pitch of 0.33nm, 2) commercial availability of designed base sequence, 3) well developed cut-and-paste and assembling techniques using biotechnology and 4) observation technology by AFMs. For creating one dimensional periodic structure, short DNA blocks are made with cohesive ends, and then they are ligated (linked by enzyme) for forming long structure. For the AFM observation purpose, gold nano particles with a diameter of 5nm is labeled on the DNA, resulting in the particle pitch of tens of nm. Some basic results of the experiments are shown in this article.

View full abstract

Touch is the most frequency used action to gather the outside information. In our daily life, various kinds of things are touched with fingers and their features are extracted and evaluated unconsciously. Tactile sensation gives not only perception of contact but also various kinds of feelings, like "rough", "soft", "warm", "comfortable", and so on. Thus, the sense of touch is indispensable to our life as well as the sense of sight. In the tactile function, contact, stroke, and other actions are used to an object for the tactile perception. It seems that most of the tactile sensors developed so far have been functional to the measurement of just force magnitude, while a few sensors are available for the rating of the feelings on an object material. This paper introduces an active palpation sensor for detecting the prostatic cancer and hypertrophy and a sensor for monitoring human hair conditions.

View full abstract

Steel cords have been in use as an important and convenient machine element for load and power transmission. Although the steel cords have been used through the ages, the fatigue damage mechanism of cords under bending has not sufficiently been elucidated. Especially, the friction force between the wires is important for the bending stiffness and the fatigue failures. In this study, the effect of friction on the failure initiation site was discussed performing some experiments and FEM analysis under cord bending condition.

View full abstract

The rubber belt for CVT in scooter transmits the power by friction between pulley and belt. The well-known transmission theories by friction are the theories of Euler and Ogasawara. However, the power transmission theory of a rubber belt for CVT has not sufficiently been understood. In this study, the power transmission theory in the rubber belt for CVT is investigated by performing the belt-deformation measurements and FEM analysis.

View full abstract

The novel mechanism CVT (Shaft Drive CVT, S-CVT) was developed by the authors. The concave disks/rollers, these were the rolling elements of S-CVT, had a difficulty to increase the torque capacity. One reason was that the increase of the spin and the contact pressure. Another reason was that the collision of the disks frequently occurs. To solve these problem, the zero-spin disk/roller was devised. At every speed ratio, the spin decreased to less than 1%. In addition to this, another problems were solved. To improve the power to weight ratio of S-CVT, an optimum design of zero-spin disk was achieved by considering the shear model of traction oil in EHL contact area, maximum Hertzian pressure and the masses of the disks/rollers. The results of calculations were that the power to weight ratio of zero-spin disk/roller was 2.3kW/kg, and that of concave disk/roller was 1.7kW/kg.

View full abstract

This paper shows design and performance of a 5-speed chain-drive shift-unit by using a parallel motion mechanism. This is applied to the speed-ratio change of a small electric vehicle with 92W power. The shift link is controlled by a stepping motor in 5 positions. The shift link succeeds to control the shift position at a 0.5mm in preciseness and 0.5s in response time. The electronically controllable shifter is possible to apply to a twin chain-drive system due to quick and reliable ratio-change of a twin motor EV.

View full abstract

A troublesome problem in flat belt transmission is called lateral motion or skew, a phenomenon that the belt moves in pulley axial direction while traveling in rotation direction. The skew is caused by angular misalignment or deflection of the pulley. There are tow kinds of angular misalignment, in-plane and out-of-plane misalignment. The former is that a pulley, driving or driven, inclines in the base plane constructed by two pulley axes, and the latter a pulley inclines in the plane perpendicular to the base plane. In this paper, the mechanism of belt skew caused by in-plane misalignment is clarified and the analytical solution derived following the discussions on some calculation results by FEM. It has been found that the skew caused by in-plane misalignment is much more complicated than that caused by out-of-plane misalignment. The skew ratio depends on both geometrical and material parameters of pulleys and belt.

View full abstract

We have proposed that the mechanism of such types of belt skew on cone type pulley, crowned pulley, and flat type pulley with inclined axis is based on the presence of an approach angle of a belt center line to a right angle with the pulley axis, and the skew rate is nearly equal to the approach angle. In this paper, another belt skew phenomenon caused by twisted cord is analyzed by FEM and the above mentioned mechanism is confirmed to be valid in this type of belt skew. In the FEM analysis, a calculation model of restoring torque by a twisted cord is studied at first. Then skew of a belt that has Z type twisted cords and is running on two pulleys having equal radius is analyzed and good agreement between results of the analysis and experiments is shown.

View full abstract

In this paper, a fluctuation of the driving torque and the shaft load in round shape synchronous belt drives and the flat belt drives under no load is studied, From the experimental results, it was confirmed that the configuration in storage of the belt influences the driving torque fluctuation and the shaft load fluctuation at the point where the belt engages or comes off the pulley. Furthermore, the experimental result in flat belt drives are compared with the results of the of the static FE analysis, Almost the same configuration of the belt in storage using in the experiments was used in FE analysis. Although the average shaft load is not equal to that of the experimental results, it was confirmed that the configuration in storage of the belt is the most important factor that influences on the fluctuation of the driving torque.

View full abstract

The transmission error that considered the error of belt side face in a helical synchronous belt drive using flanged pulleys under the quasi-static condition and transmitted torque was investigated theoretically for the case where the pulley was rotated in bidirectional operation and the pulley speed ratio was 1:1. The calculated transmission error in forward rotation results from axial belt movement due to the error of belt side face when the belt comes into contact with the pulley flange, and that over a period of one rotation of the belt occurs. The transmission error in reverse rotation is generated by a change in the belt tension under transmitted torque and by the difference in axial belt movements between the driving and driven sides, and the quantity of that is different by the pulley stop position in forward rotation.

View full abstract

Noise and vibration problem likely happens after assembly even every element is manufactured under low vibration design. Therefore it is helpful if vibration measurement can point out the actual geometrical situation concerning such alignment information like bearing pattern between teeth, or relationship between mating tooth surface forms. Present paper tries to extract accurate waveform from vibration measurement by the aid of synchronous averaging and Fourier analysis. Provided several driving helical gears having identical nominal dimensions but different tooth surface modifications, measurements were done by mating with an unique driven helical gear. Signal were averaged synchronous with shaft rotation, and then Fourier coefficients were calculated. Next mesh harmonic components have been normalized with respect to mesh fundamental component, and are shown as named polar plots that represent particular tendency against loading condition. The results clearly suggests it is applicable to diagnose a faulty gear system.

View full abstract

In this report, authors propose centrifugal vibration absorber to reduce gear mesh vibration due to input shaft pinion. Input shaft of transmission is often cantilever shaft. Shaft bending brings misaligned mesh and high level vibration. Centrifugal vibration absorber is set on input shaft on two stage gear system, and its efficiency is verified experimentaly measuring each shaft rotational vibration.

View full abstract

It is said that helical gears with bias tooth surface modification, a kind of three-dimensional modification, can secure quietness within the wide range of transmitted load. However, its theoretical grounds have not been clarified in the past researches. Helical gears with theoretical involute helicoid have the character that lowers mesh exciting force within the wide range of transmitted load when the transverse or overlap contact ratio becomes an integer. In this paper, the relationship between tooth contact condition and tooth stiffness in such gear pair is discussed. As a result, theoretical grounds for the effectiveness of the proposed three-dimensional modification are clarified. In addition, the way of designing three-dimensional modification to the helical gears that have the arbitrary contact ratio is proposed and the effect is examined by the theoretical analysis.

View full abstract

The purpose of this research is to derive the meaningful parameters and the new procedure of measurement of tooth flank topography to evaluate the individual gear accuracy objectively. For this purpose, the tooth flank topography is characterized as the curved surface and the parameters for tooth flank topography are derived from the 3-dimensional measured deviations of tooth flanks. After derivation of a new definition of the pitch deviation, the parameters for the 1st and 2nd order form deviations are derived. Using those parameters, three-dimensional modification of a tooth flank is characterized according to the order of the surface. They can be calculated from the measured conventional deviations and separation process of measured deviations into 1st and 2nd order form deviations are automatically performed and the parameters are calculated at the same process. Actual gear flanks of a bevel gear are measured and the newly proposed parameters are calculated and evaluated.

View full abstract

It has been reported that the vibration of the gears with convex tooth flank form is low when the actual contact ratio takes integer + 0.6 approximately. Those reports were, however, concluded only by the investigation for some sample gears. Therefore, the characteristics of transmission error of gears are not clarified theoretically. In the previous reports, general model of tooth mesh of gears has been proposed, where quasi-infinite elastic model composed by springs with stiffness peculiar to gears is incorporated and transmission error of gears has been expressed by theoretical equations. In this report, the influence of tooth flank form deviation on transmission error is investigated by general model. It is clarified that form of ridge curve of tooth flank form deviation has much influence on the actual contact ratio corresponding to the minimum amplitude of transmission error.

View full abstract

Today it is very important to improve gear noise from the environmental point of view. However, conventional measuring method of vibration level such as bench test requires much time, and simulation analysis to expect NV performance becomes more important. This paper shows the reliability of performance simulation of Hypoid Gears and our way to develop quieter gears.

View full abstract

It is well known that the characteristics of exiting force of gear mesh is varied with gear mesh phase between pinions in single pinion type planetary gears. In this study, relation between gear mesh phase and vibration behavior is investigated in stepped pinion type planetary gears which is operated at wide frequency range. By taking into account side band order of gear mesh, it was revealed that influence of gear mesh phase on vibration transmission property is varied by frequency range. It is considered that the dominant direction component of exiting force for vibration transmission property moves from transverse direction at low- frequency range to rotation direction at high-frequency range.

View full abstract

A strain wave gearing is a kind of K-H-V type planetary gears. It has features of lightweight and high reduction ratio. This paper deals with the relationship between the radiated noise of strain wave gearing and the vibration of F/S. The magnitude of sound power is expected to become large in proportion to the square of the amplitude of displacement of F/S. The displacement is calculated using FEM and measured. The sound power is also measured using the F/S fixed type apparatus. It is confirmed that the relation between them are agreed well to the theory and the reason of noise is caused by the vaibration fo the F/S.

View full abstract

To prevent the machine plant from breaking down, there are many methods such as acoustic emission, vibration, noise, ultrasound, temperature, and so on. In this study, both vibration method and detection of iron powder in the oil using magnet were applied to detect the failure of steel gear sets. The wavelet Transform (WT) is a method for the time-frequency analysis. A failed tooth could be found out by the change of WT intensity of the vibration acceleration, giving attention to the frequency band near the tooth meshing frequency. When the plural teeth were failed by pitting, the output of the iron powder sensor using magnet was changed. However, the increase in the iron power did not detected at the initial fatigue stage.

View full abstract

The flow of the medium at the mesh area of a helical gear has been visualized by the experiment using transparent acrylic gears and a water tank. Among two major roll of lubrication, reducing friction and cooling, cooling is quite important for maintaining gear durability because high temperature has metallurgical effect. Lubrication also makes excess power loss by squeezing effect at mesh area as well as by various losses existing in feeding system such as pump loss. Therefore, for the efficient contribution of lubricant, it is necessary to find an optimum arrangement of oil feeding especially for the purpose of cooling. This paper has described how to visualize the flow of the medium of the engagement part whose observation was not completed by the conventional method. The flow at mesh end region was observed clearly through gear body by using milk or plastic particles.

View full abstract

The transmission comprises many machine elements. These machine elements demonstrate the function by lubricating under the good condition. The lubrication under this good condition is to sufficiently supply not deteriorating lubricating oil. The general transmission is used under the condition of oil bath. Therefore, the lubrication to each machine element is the splash lubrication by the gear. In addition, the primary cause of the degradation of lubricating oil is the decomposition of the additives by temperature rise of lubricating oil. Then, it becomes the importance that the lubricating oil of the splash is efficiently cooled. Therefore, it is important to know the behavior of the lubricating oil with the splash. However, the research of this field hardly has been done in present state. In this study, the fluid behavior which spur gear splashed was observed by the high speed camera, and the splash quantity was measured by using the splash collecting equipment.

View full abstract

VGR (Variable Gear Ratio) rack & pinion is a machine element that the rotation angle of the pinion changes the movement distance of the rack. It is used the power steering device for the car. As a result, the conflicting performance it is the stability when going straight and the steer when turning can be improved at the same time. When the motion of this mechanism was evaluated, the error was caused in the theory value and measurements in the movement distance of rack to rotation angle of pinion. Then, the cause of the error is examined by the measurement tooth surface is compared with the theory tooth surface. There, it is shown that this error is influenced by the lead error in right tooth surface from relation of lead error and contact line.

View full abstract

In this research, the simulation system of generating the gear profile is developed. The shape of the rack can be designed flexibly on the developed system, the various shape of generating gear profile with is enabled. To display only a generating gear plofile, the shape of the rack is dividede into tooth depth and tip, each of envelope curve is obtained from generating motion.Using the developed system, the various gear profile can be simulated.

View full abstract

To realize ultra precise machining or measurement, a machine system generating accurately relative motion between its tool and the workpiece is required as well as the accuracy improvements of each element of the machine. This paper proposes a machine system using a compensation device for 6-degree-of-freedom (6-DOF) motion errors between the tool and the workpiece. A hexapod-type parallel mechanism installed between the tool spindle and the surface plate is passively actuated by a conventional machine. Then, the parallel mechanism measures the 6-DOF motions regardless with temperature fluctuation and external forces because the mechanism has a compensation system for elastic and thermal errors of the joints and the links. Therefore, the tool position and orientation are compensated by using the measured 6-DOF errors. This paper describes the conception and the fundamentals of the system. Moreover, a passively extensible strut with a compensation device for the joint's errors was tested.

View full abstract

This paper describes a method to systematically calculate forward dynamics of planar closed-loop mechanisms. Analytical equations to obtain the acceleration coefficients of joints on a crank, two adjacent links and a coupler link are derived. After solving a system of linear equations with respect to crank accelerations and joint forces, nonlinear differential equations on the mechanism could be solved with a numerical method. Forward dynamics of a planar 4-bar link mechanism and 5-bar link mechanisms with 2DOF were analyzed, it was then confirmed that the proposed method was effective and useful.

View full abstract

In the present paper, singularity analysis of a 3-URU non-overcontrained spherical parallel mechanism with three degrees of freedom has been theoretically discussed. Based on the screw and reciprocal screw of each connecting chain, condition for constraint singularity has been derived, and some concrete conditions have been presented. Deriving the velocity relationship between input and output based on the concept of reciprocal product, conditions for actuation singularity and reach limit singularity have been derived. Condition for local-mobility singularity has been also derived, and an example has been presented. Numerical calculation technique to accurately find these singular points in the workspace has been also discussed.

View full abstract

The environment where Japanese industry has been paid with respect is changing tremendously due to the globalization of economics, where Asian countries are undergoing economical and technical development as well as advancing in information technology. For example, in the design of custom-made casting product, a designer whom lacking of casting knowledge may not be able to produce a good design. In order to obtain a good design and manufacturing result, it is necessary to equip the designer and manufacturer with a support system related to casting design or so called, knowledge transfer and creation system. This paper proposes a new virtual reality based knowledge acquisition and job training system for casting design, which is composed of the explicit and tacit knowledge transfer system using synchronized multimedia and the knowledge internalization system using portable virtual environment. In our proposed system, the education content is displayed in the immersive virtual environment, where by a trainee may experience himself in the virtual site operations. Provided that the trainee has gained explicit and tacit knowledge of casting through the multimedia-based knowledge transfer system, the immersive virtual environment catalyzes the internalization of knowledge and also enable the trainee to gain tacit knowledge before undergoing on the job training at real operation site.

View full abstract

The person who is in the state of bedridden for a long time cannot become a difficulty in sit up or in walking by the muscular power decrease and the articular atorofy of lower limbs. In this study, the translation movement type leg training machine performed with a back posture was developed for the purpose of the rehabilitation in the lie on one's back posture. The leg training is experimented using this machine about the healthy persons and a pseudohandicapped person. The position of the parts of the body, the hip pressure the foot pressure and the surface temperature of each part of the legs are measured. The basic data as the machine installation angle and the backrest angle, the movement amplitude and frequency in consideration of a trainer's condition are obtained for performing optical training using this machine.

View full abstract

Knee movement involves a complicated combination of translations and rotations. Therefore, adequate motion analysis of implanted knee is necessary for estimating the wear of inserts and improving the design of artificial knee joint. This study was aimed to determine the kinematics of total knee arthroplasty (TKA) component during a kneeling activity, stair climbing and walking motion in vivo using image matching technique with a high-resolutional flat panel detector (FPD). The fifteen patients with cruciate-retaining (CR) TKA were examined using this motion analysis. Our analysis could reproduce the in vivo relation of contact between a femoral component and polyethylene insert on a computer. Additionally, motion analysis of artificial knee implants could clarify typical motion patterns depending on patient. Kinetic analysis using our method would be useful to improve the design of artificial knee joint and clinical evaluation.

View full abstract

We have developed a micro capacitive inclination sensor that has an outer dimension of 5mm×5mm×2mm and a linear analog output. This sensor is unique in two ways. Firstly, we have se-lected a method to improve the permittivity of the dielectric oil by mixing it with dielectric nano-particles. This method allows us to achieve miniaturization and high performance of the sensor easily. The second feature is the adoption of a slit structure and a pseudo channel in order to mitigate the influence of the surface tension of the dielectric oil. As a result of evaluation of the sensor, we obtained a linear and analog output within an inclination angle range from 0-45 deg. The detection resolution and the response speed were 0.1 deg or more and 0.79 sec/deg respectively. Based on these achievements, we attained a certain perspective to miniaturize inclination sensors.

View full abstract

In this study, we have tried to assemble small parts by using micro manipulator. In this case, it is necessity to inject binding material at narrow area (from 10μm to 0.1μm). This report discusses a pipetting device that can inject small quantities (from sub-pico liter to femt litter range) of binding material. Because the size of the micro pipette used to dispense is minute, the surface tension of the adhesive and the influence of the viscosity are very greatly related. Then we develop the pipetting device using the force of gravity by free fall, and experiment the performance of pipettes with different point angle. From experimental result, we obtain the relation between the point angle of pipette and the quantities of binding material.

View full abstract

In this paper, the cleaning method of dusts on the surface of window glass for cleaning robots has been investigated. In the interactive surfaces between the brush of wiper and window glass, we have examined how the curvature radius of the brush against the glass surface is affected by pressure force. First, the dusts on the window glass at the outside of the building have been grown naturally in the condition that the specimen is put on about 18m height widow and during 70days. Second, a stainless micro cantilever glued a glass or a plastic sphere having curvature radius 5μm or 10μm have been created. In the experiments, the contact-mode AFM (Atomic force microscope) with the stainless cantilever is used. In the results, the AFM cantilever pressure force more than 400μN was needed to clean dusts on the surface of the window glass after exhibiting more than 70 days. Then the volume and height of the dust and the AFM cantilever pressure force after cleaning by cantilever were measured. And it was effective that the curvature radius of the brush of a cleaning robot becomes smaller in the case where the pressure force is same.

View full abstract

A miniature moving robot composed of plastic injection-molded pantograph mechanisms based on different modes of resonance is proposed. Plastic injection molding techniques and printing by using molds are effective to make small parts in micromachines and MEMS devices. The proposed injection-molded pantograph mechanisms have large-deflective hinges as pair. Because the deflective hinges has no clearance, propagation of vibration goes through mechanisms easily. Vibration is regarded as an effective way to drive micromachines in consideration of simplicity of mechanisms, availability of small PZT actuators as a driving element, power density, and prevention of a sticking phenomenon between small parts. In this reports, basic vibration behaviors of a molded pantograph mechanism were investigated experimentally. Then, a three-leg moving robot composed of molded pantograph mechanisms and PZT oscillators was fabricated. In our experiments, even only one leg could drive the robot independently in forward(37mm/s at 8.0Hz), backward(54mm/s at 8.4kHz), and rotation directions(0.23rad/s at 3.0kHz) with different input frequencies.

View full abstract

There are many requirements to manipulate manufacturing products and bio-sample. We propose a light driven micro-manipulator to provide appropriate force and object size in the area of from μm to mm. It consists of three optical fiber cantilevers driven by laser light made of plastic with polished to bevel and black coating. It moves 50μm of displacement and 200μN of trapping force at 25mW of light intensity. A manipulation system is proposed using three fiber actuators under microscope. It can succeed to manipulate iron and glass particles with 50μm diameter and fabricate three-dimensional structure.

View full abstract

A new robotic system that locates an underwater chemical source is proposed. Dispersal of odor molecules is confined in the vicinity of their source under stagnant flow conditions. Therefore, a crayfish creates directed water currents by beating maxillipeds vertically, and draws odor molecules from the surroundings to the chemosensory organs. The proposed system consists of an array of chemical sensors and fanning devices that mimic the maxillipeds. In the experiments, the system was suspended from a set of actuators in a plastic aquarium, and was challenged to detect chemical substances released from the surroundings. Active flow generation by artificial maxillipeds was found effective in drawing chemical samples from a wide angular range. Successful results were obtained on navigating the system to a chemical source using the chemical sensors.

View full abstract

This paper describes a motion control of hyper redundant robots to utilize their redundancies as much as possible for simultaneously achieving several target motions. The dexterity of hyper redundant mechanisms was assumed as the effectiveness of actuators to achieve target motions and was thus defined as the average of 'Partial Singularity Index: PSI' of each actuator. In order to maximize the dexterity and assist the achievement of main task, an effective method to set subtasks was proposed. Several simulations with a planar 10R serial manipulator revealed that the proposed method was effective and useful.

View full abstract

We have already proposed a disk brake for robotic use in which the braking torque is generated both by PZT-actuator and solenoid. The action of the solenoid is transmitted to friction pads through a wedge mechanism. A prototype brake of total mass 1.2kg has been manufactured and realized 2.4N・m braking torque. But braking torque of the prototype brake was sensitive to the manufacturing error of brake parts, and experiential fine tune-up was needed to realize such a large braking torque. In this paper, in order to make clear the relation between manufacturing error and brake application force, we proposed a contact model which can take into account of uneven contact with lower computing cost than FEM. Dynamic simulations with this proposed contact model and experiments have been carried out to investigate relationship between manufacturing error and brake application force. Based on these analyses, we proposed a method to minimize effects of manufacturing error on brake application force.

View full abstract

It is important to make clear the human motion in the field of robotics and welfare engineering. Especially, the kick motion in the football is generated by the high joint torque, so it is difficult to simulate with the experimental device. The improving the effective manner of the generating motion with the multiple joints is the general problem in the mechanisms, so it is expected that the method of the mechanism can be applied to this problem. In this research, we designed the experimental device with the planar open four bar links to measure the angular displacement at the joints, and we investigated the effective form of kick motion.

View full abstract

In this research, we developed the emergency vehicle that can be driven at a high speed with stability on the road in a mountainous region where is torn by a landslide. Original vehicle was a snow mobile, it was expected that the thrust can be obtained by truck belt keeping the contact with the ground even if the surface was in a rough state. The ski plate was remained for the purpose of the skid guide to get over a barrier, and the wheel were attached to the steering gear to be driven at a high speed on the asphalt-surfaced road. The method of the steering simulation was suggested in this research to make the steering performance improved.

View full abstract

A slider-crank mechanism whose coupler curve is the approximate ellipse is designed so that the human may perform the pedaling of the elliptical motion of the foot. Because the thigh, the shank, the foot of the human constitute the three link chain, the system of the human and the bicycle with the slider-crank pedal mechanism may be considered as the seven planar link mechanism of two degree freedom. On the other hand, the system of the human and the ordinary bicycle may be considered as the five planar link mechanism of two degree freedom. Kinematic characteristics of these systems are analyzed with the given pattern of the pedal angle curve during a crank rotation. Then, the crank moment and the pin joint forces of these systems are calculated for given patterns of the hip moment, the knee moment and the ankle moment during a crank rotation and the average crank moment is estimated. The results of the pedal angle, the pedal force and the crank moment are verified experimentally.

View full abstract