A prosthetic foot is one of the key components to realize stable and efficient amputee gait. Characteristics and comfort of the amputee gait depend on the mechanical properties of prosthetic feet. In order to clarify the effects of dynamical amputee gait on prosthetic feet, we should focus on the individual mechanical properties of prosthetic feet unlike the conventional methods with a prosthesis applied to the able-bodied person. From this point of view, this paper describes the construction of a dynamic loading test device based on ISO22675, with a 3-axis pylon load cell for evaluating mechanical properties of prosthetic feet in sagittal plane. It is confirmed that a 3-axis pylon load cell applied to a cantilever structure shows high sensitivity under loading condition of ISO22675. On the dynamic roll-over analysis of three kinds of prosthetic feet in sagittal plane, the following properties that precedent studies provided are experimentally confirmed : the roll-over shape of a prosthetic foot for low activity user shows a large curvature in the middle period of stance phase. It is also found that the mechanical deformation property does not change under the test cycles of 2.0 and 4.0[s], because both FCP (Force Contact Point) trajectories during roll-over show a similar tendency.

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This paper presents a novel path-following feedback control method of two manipulating points defined on a carrier of a cooperative transportation system with two car-like mobile robots. Since the path-following feedback control method previously presented by the authors causes the first car-like mobile robot to follow a path and causes the orientation of the carrier relative to that of the tangent of the path to be constant, the carrier is swung around during the transportation in cases where the curvature of the path is high, increasing the risk of overturning the load on the carrier. To resolve this problem, this paper presents the novel path-following feedback control method which causes both of the two manipulating points on the carrier to follow the path. This method makes it possible to design the motion of the carrier as that of a segment between the two manipulating points. The kinematical equation of the transportation system is converted into a chained form in a coordinate system where the path is one coordinate axis and a straight line perpendicular to the tangent of the path is the other coordinate axis. The convergence of the position of one manipulating point into its desired position on the path is guaranteed by the linear control theory, and that of the position of the other manipulating point is guaranteed by the Lyapunov 's second method and the Lyapunov function is designed based on the chained form. The validity of the novel path-following feedback control method is verified experimentally.

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The objective of this study was to clarify the effects of men's swimsuits on swimming position and muscle activity of body trunk in gliding motion. For this objective, a swimming experiment to measure electromyogram and gliding position in sagittal plane simultaneously was conducted for 3 types of men's swimsuit (A, B and C). Next, we compared experimental results one-on-one between the swimsuits by ANOVA. The results of the experiment and ANOVA showed that in wearing Swimsuit C, compared to Swimsuits A and B, hip became lower to shoulder (p<0.05), the hip joint became more extended (p<0.05), and the muscle activity of ES (Erector Spinae) and drag coefficient had tendency to decrease. In addition, we established a new index for the effect of body trunk support, which corresponds to the muscle activity of ES considering the change in the hip joint angle. We confirmed statistically that Swimsuit C had effects of extending hip joint and/or reducing the muscle activity of ES (p<0.05). The reason for this was considered to be that the Swimsuit C helped the hip extensor muscles.

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A simple dynamic model is useful to understand the essential dynamics of an occupant in car crash and will be effective to determine the properties of protection devices. In this paper, a reduced-order dynamic model is introduced based on human finite element (FE) model having age-specific characteristics such as bone stiffness and tolerance of the body. The reduced-order dynamic model consists of two masses and one rigid body. The two masses correspond to the thorax and the lower body, and the rigid body corresponds to the upper body. The mass representing the thorax was connected to the upper body by a spring and a damper in parallel to consider the thoracic deflection, which is one of the representing injury criteria in frontal car crash. The comparisons of the responses between the reduced-order dynamic model and the human FE model were conducted in frontal car crash and indicate that the reduced-order dynamic model can approximate the thoracic deflection, the thorax displacement, and the lower body displacement.

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This paper deals with the disturbance rejection performance of a posture control method based on imaginary impedance for a six-legged robot. In the mechanism proposed by Hirose et al., the thigh links are important for controlling the body posture. Angular errors occur in these thigh links, when the robot walks over a step obstacle, angular sensors generate error signals, or zero point errors of angular sensors exist. In this study, we consider the errors as a step disturbance. We first derive a mathematical model for posture control in the presence of a disturbance. Next, a LQI controller based on imaginary impedance is designed to suppress the effect of the disturbance. The disturbance rejection performance of the proposed posture control method is verified by 3D simulations and experiments.

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The present study was carried out to clarify characteristics of human motion and perception and to support the development of a force perception model for vehicle operation. This paper describes initial experimental analysis of human force perception characteristics relating to steering operation, which involves multiple joint motions and large postural changes of the arms. The results highlighted three points in particular: (1) force perception follows the Weber-Fechner law when arm posture is constant; (2) force perception depends on the steering wheel angle and is affected by the weight and stiffness of the arms; and (3) force perception does not depend on the preceding state of the arms before perception.

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This paper describes a method for estimating the crosswind disturbance and the transverse slope affecting a passenger vehicle that is travelling in a straight line. It also discusses a compensation control system that uses electric power steering to provide steering assistance to the driver. Under ordinary driving conditions, the aerodynamic sideslip angle remains small, and therefore, the center of pressure remains reasonably stable. In this study, a constant center of pressure is assumed, and a lower-order disturbance observer is designed so as to reduce the computational cost of the implementation. The transverse slope is estimated independently of the crosswind, and the compensation torque of the electric power steering system is determined by the crosswind component. Vehicle dynamics simulations confirmed that the yaw rate could be reduced by using the proposed quartic disturbance observer.

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The fluid force of labyrinth seals may cause unstable rotor vibrations in turbo-machineries. In this research, dynamic characteristics of double strip labyrinth seals were measured by using a test rig. The rotor-bearing system was supported by soft cage springs, and it was excited using a magnetic bearing. Cross-coupled stiffness was calculated and evaluated as unstable dynamic characteristics of the seals. Experimental and calculation results showed cross-coupled stiffness increased, when the rotating speed increased. Otherwise cross-coupled stiffness decreased, when the differential pressure increased. Unstable fluid force of double strip labyrinth seal depends on axial fin position of rotor and stator. When fin position of rotor accord with stator, unstable force arose from upstream cavity and stable force arose from downstream cavity. Upstream of double strip labyrinth seal had a more stabilizing effect, when fin position accord.

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We measured the change in brightness of vascular images taken with near-infrared light during upper arm compression, and brachial-ankle pulse wave velocity (baPWV), which was calculated from the difference in pulse-wave transit time between the brachial artery and the ankle artery. The correlation between these measures was determined in 52 male subjects of different ages (22 to 66 years). The dorsal surface of the proximal interphalangeal joint of the right index finger was illuminated with near-infrared light (wavelength: 850 nm), and a vascular image was taken of the palmar side with a CCD camera during cuff compression (80 mmHg). The time it took for the change in brightness to reach 50% of the convergence value (half-convergence time) was calculated based on the measured change in brightness. The half-convergence time indicates venous compliance, and baPWV indicates arterial compliance. There was a negative correlation between the half-convergence time and baPWV (r = -0.688, p < 0.001). This correlation may be accounted for by age-related changes in the elastin and collagen that comprise the vascular walls of the artery and the vein. We consider these changes to have a similar influence on the half-convergence time and baPWV. We could therefore estimate arterial compliance by measuring venous compliance.

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This paper considers the automatic parameter tuning for the position control of the linear stage. To improve the performance of the positioning, feedback error learning (FEL), which reduces the output of the feedback controller for the learning, is utilized. Effects of the FEL's parameters (i.e., the reference, the gain of the feedback controller, the learning rate, and the parameter of the feedforward controller) are investigated by experiment. The large amplitude of the reference is effective in terms of the learning accuracy, and the large parameter of the feedforward controller is effective in terms of the learning time. The suitable learning rate and the feedback controller's gain are selected by considering the oscillation of estimated parameters. Furthermore, to shorten the learning time and improve the positioning performance, the termination test of the FEL is presented. In this method, the learning is automatically stopped based on the change of time integral of the estimated vector. Experimental results demonstrate the improvement of the parameter tuning.

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The study deals with the incremental stretch-expanding process of a sheet metal using hammering. Although current incremental forming is a method of plastic working that employs basically static force, it is also possible to use dynamic force through impact, such as through free forging and hammering. If dynamic force is used, more flexible thickness control is expected compared with static one. The study has constructed the work method and succeeded to form some comparatively primitive shapes. However, formability of the work results differs according to the tool paths in this method. Thus, unsuitable tool paths threaten to cause both deterioration of work accuracy and extreme thickness decreasing or fracturing. However, relationship between the tool paths and formability has not been discussed sufficiently. Therefore, in this study, tool paths which the work method can select is classified correctly, and effect of each tool path on strain distribution is particularly experimented and discussed to clarify the forming principle. Furthermore, an optimum tool path generation method is discussed based on these conclusions. As the result, flexibility of thickness control as an advantage of the method is confirmed.

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In recent years, there has been growing demand for high precision products made by progressive die forming, in which pilot holes are formed on the sheet material to maintain feeding accuracy. Pre-punch holes are also made on the sheet material. The shearing conditions affect sheet material deformation. Therefore, it is important that the influence of the shearing conditions on the sheet material deformation is clarified to enable the fabrication of high-precision products by progressive die forming. In this study, the influences of the shearing conditions on the deflection of the pilot pin and material deformation was investigated experimentally and by FEM. This study clarified the following. The deflection of the pilot pin exists after shearing. The experimental results and FEM results obtained using the circular specimen confirmed that residual deformation exists in the specimen after shearing. The deformation of the specimen decreases with increasing specimen diameter.

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For the evaluation of oil supply condition in ball bearing, the variation of transmittance H_T2 affected by the condition of film formation between an outer ring and a ball was observed. When sufficient oil is supplied to the inlet of contact surface and the oil film is ruptured in outlet side, local transmittance measured by point focus probe having 0.2mm focus diameter is increased locally near the contact point of inlet and decreased suddenly at outlet point. Since the H_T2 observed by normal probe having irradiation width of 3.5mm is the value averaged in 3.5mm width which covers inlet and outlet side, however, observed H_T2 has a hump through the wide range in inlet region of ball and decreases gradually near the contact point, and minimum value in H_T2 appears at outlet region far from contact point. For the desiccation of oil, the hump does not appear at all and the position of minimum transmittance agrees with the contact point. Moreover, it is cleared that the area of closed curve formed by the relationship between H_T1 (transmittance from the interface of housing and outer ring) and H_T2 decreases considerably with oil insufficiency. And its area is kept almost constant with desiccation of oil. Furthermore, the transmission degree estimated by transmittance H_T2, which propagates through the boundary of outer ring and ball, becomes an effective index. This value is increased through oil insufficiency process and kept almost constant for the desiccation of oil.

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Automatic reed valves are widely used to control refrigerant gas flows in reciprocating compressors for automotive air conditioners. The oil film in the clearance between the reed and the valve seat causes a delay in opening of the valve. This opening delay of the discharge valve leads to over compression, which increases losses in the compressor. This study aims to develop an experimental setup that enables simultaneous visualization of the oil film rupture and measurement of the reed deformation, and to observe this behavior during the valve opening process. The gas-compression stroke is simulated by controlling compressed air with an electromagnetic valve. The oil film rupture is visually observed using a high speed camera through a special valve seat made of glass. The total deformation of the cantilever reed is identified by multipoint strain measurement with 12 strain gauges. The experiment finds that the opening process is divided into four stages. In the first stage, the reed remains stuck to the seat and deforms while the bore pressure increases. In the second stage, cavitation occurs in the oil film and the film starts to rupture. In the third stage, the oil film ruptures and the bore pressure starts to decrease. Finally, in the fourth stage, the reed is separated from the seat and the gas flows through the valve. Reducing the reed/seat contact area changes the reed deformation in the first stage, thereby increasing the reed/seat distance and realizing an earlier oil film rupture and a shorter delay.

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Brain-machine interfaces (BMIs), which connect brain tissue to machines, have been investigated extensively in recent years. The main purpose of a BMI is to assist paralyzed patients by enabling them to operate machines based on their own brain activity. In this paper, we measure brain activation using near-infrared spectroscopy (NIRS) so as to clarify the relationship between the consciousness and unconsciousness in the motion. It is hope that the results obtained in this study can be applied to machine operation using a BMI. Bio-locomotion is divided into voluntary movements, which are made voluntarily and consciously, and passive movement, which are made passively and unconsciously. Accordingly, we investigate the brain activation associated with these two types of movement. The subjects successively move their lower legs through knee bends using a vibratory device which we made to conduct experiments. The result showed that the concentration of oxygenated hemoglobin (oxy-Hb) levels change in the primary motor cortex and the prefrontal cortex during the voluntary movement. We found that the passive movement has little effect on the brain activations. In addition, we measured brain activities during passive movements and vibratory motion. In passive movement, legs are moved passively and unconsciously by vibrations. In vibratory motions, legs are not moved by vibrations. As a result of the measurement, the brain activation of the passive movement is similar to that of the vibratory motion.

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This paper proposes a design process planning method evaluating individual technical performances and total product integrity. A planning of design process is a complicated optimization problem including a number of various design variables and various evaluation indices. In order to solve this problem with a reasonable computation cost, this research introduces a two-phase optimization problem. The first phase is defining of process architecture and organization structure and. The second phase is scheduling of resource allocation into activities. A growth curve model with a fuzzy number is used to evaluate the achievement probability of technical performance and its total integrity. This paper demonstrates its application to a student design project. A proposed planning method facilitates a project manager to explore various process plans, to assess their risks, and decide a temporary plan.

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