Takashi Mitsuda

Wearable haptic display by the use of a Particle Mechanical Constraint

A Particle Mechanical Constraint is a soft vinyl tube that envelops Styrofoam beads. It has 6 degrees-of-freedom including compression, elongation, bending and twisting. By exhausting the inside air the PMC solidifies and constraints all degrees-of-freedom in an arbitrary shape. The stiffness of the PMC is proportional to the inside air pressure. Viscosity is also controlled virtually by changing the inside air pressure in proportion to the speed of transformation of the PMC. By the use of a PMC, we developed a wearable haptic display that provides a sensation of contacting a wall and moving in water with viscosity. We also developed an upper-limb orthotic that constrains shoulder and elbow movements. PMC is adequate as a wearable human interface because it is light, soft and safe. In addition, it is an inherently passive device that never exerts excessive force when broken.

Haptic displays implemented by controllable passive elements

Conventional robot systems consist of hard mechanical elements and actuators for exerting a force to objects efficiently. These systems are taking remarkable activities in industrial field but not in daily life of human. Main disadvantage of these robot systems is the fatal risk to human body when they lose control in the case of breakdown. On the contrary, we focus on flexible robot systems that work passively without actuators. These systems are intrinsically safe to human body since they never exert any excessive forces. In this paper, we present a novel passive element that varies its stiffness to internal vacuum pressure. This passive element is a soft vinyl tube embedded with Styrofoam beads, and is therefore soft and light contrary to conventional passive elements. Using the flexibility and the controllable stiffness, we developed a wearable haptic display that provides a sensation of elasticity and viscosity. The design of this new passive element and the applications to haptic displays are discussed.

Wearable force display using a particle mechanical constraint

A particle mechanical constraint (PMC) is a soft vinyl tube containing Styrofoam beads. It can be freely compressed, elongated, bent, twisted, or otherwise manipulated in all degrees of freedom. Evacuation of the air inside the tube makes the PMC rigid so that it maintains whatever shape it has been given. The stiffness of the PMC is proportional to the reduction in internal pressure below atmospheric pressure. Viscosity is also controlled virtually by changing the inside air pressure in proportion to the speed of transformation of the PMC. We used a PMC to develop a wearable force display that provides the sensation of coming into contact with a wall or of moving in water with viscosity, in addition to that of moving in air. PMC is an inherently passive device that never exerts excessive force if it were to malfunction. In short, it is suitable as a wearable human interface because it is light, soft, and safe.

Gaze bias during visual preference judgements: Effects of stimulus category and decision instructions

Prior research has demonstrated that during two-alternative decision making, gaze is biased towards the alternative that is eventually chosen. The Gaze Cascade model proposed by Shimojo, Simion, Shimojo, and Scheier (2003) predicts a larger bias for decisions requiring one to choose the item that is liked the most versus decisions that require one to choose the item that is disliked most. More recently, Park, Shimojo, and Shimojo (2010) showed that preference formation operates differently during decisions among faces and scenes, which suggests that gaze bias might differ depending on whether the decision stimuli are faces or scenes. In the present study we tested these two hypotheses in a within-subject design. Eye movements were monitored while participants (n = 48) made two-alternative Like or Dislike decisions among pairs of faces or scenes. We found remarkably little influence of stimulus type on gaze bias for either decision task, which disconfirms the hypothesis that gaze bias operates differently for faces than scenes. In contrast, we found that gaze bias was stronger for Like decisions than Dislike decisions. To further account for this effect we examined the decision time course, which revealed that this task effect is primarily related to biases in the placement, and duration, of the final dwell prior to response, although there was evidence that the bias began earlier for Like decisions. Implications for mechanisms of gaze allocation during multi-alternative decision making are discussed.

Exponential-exponential cosine fitting of blood pressure decay induced by a long-acting calcium blocker, amlodipine, using home blood pressure measurement

Blood pressure (BP) decay data obtained from home BP measurements in six patients with uncomplicated essential hypertension treated with a calcium blocker, amlodipine, were fitted to an exponential–exponential cosine function to determine the characteristic BP‐lowering effects of amlodipine. An exponential–exponential cosine function fitted the morning and night systolic BP (sBP) decay data better than a simple exponential function. From the coefficients of the equation, the estimated BP lowering, time constant for BP decay and BP oscillation induced by amlodipine for morning and night sBP were approximately 23 and 25 mmHg, 10 and 6 days, and 12 and 12 mmHg, respectively. Diastolic BP showed a similar fitting though the fitting was weaker. The fitting results indicate that the BP decay, especially the sBP decay, induced by amlodipine occurred in an oscillative fashion, and the present analysis using home BP data may provide clinically useful information about the characteristic effects of amlodipine.

Precise planar positioning using visual servoing based on coarse optical flow

In the drive towards miniaturization in manufacturing, accuracy in positioning minute objects by camera is vital. For visual servoing, the rapid and robust detections of features in camera images is also essential to production line efficiency. Template matching provides flexibility in achieving this, often lacked by other methods, because it avoids the need to set object-specific parameters. Unfortunately, standard methods of template matching require much calculation, especially for detecting feature rotation. The delay this causes means that for many applications template matching provides too slow a source of visual feedback. As an alternative, we propose a new method of detecting the translation and rotation of a feature from coarse optical flow, we and apply it to visual servoing. Coarse optical flow is derived from the difference in intensity between a region of the initial and current image and their pixel-by-pixel intensity gradients. Unlike template matching, our method can detect large rotations with relatively little calculation. Image resolution is then adjusted from coarse to fine. Subpixel accuracy results in a 100 fold improvement in precision (by area). We show experimental results for precise planar positioning.

Pseudo Force Display that Applies Pressure to the Forearms

Conventional force display systems provide a force sensation by applying force to the operators body via actuators such as electric motors. These systems can potentially harm the operator, especially when providing a large force sensation. This study shows that constrictive pressure on the distal part of the forearms provides a force sensation such as holding a heavy object or pushing a wall when the pressure changes in accordance with the hand motion. This force display provides a large force sensation of ∼10 N without applying real force to the operators hand, which makes the system intrinsically safe and suitable as a wearable force display system. Experimental results show that the discrimination thresholds are consistent with Webers Law. It was demonstrated that an operator could sort virtual objects by weight using this system.

Application of near-infrared spectroscopy to measuring of attractiveness of opposite-sex faces

Brain imaging technology employing near-infrared spectroscopy (NIRS) has great potential in various applications to daily life, by virtue of offering handy equipment and an easy measurement method. In this paper, we propose a novel application of NIRS to evaluation of feeling. As compared with an electroencephalogram, the NIRS offers easier attachment of probes on the scalp, because it does not require any paste. As compared with the magnetic resonance image system, the NIRS can detect hemodynamic response by much smaller equipment. To examine the suitability of NIRS for evaluation of feeling, we measured hemodynamic responses in the left anterior frontal cortex, which we then correlated with reported assessments of facial attractiveness. Oxy-hemoglobin in the area increased when the subjects evaluated the faces as unattractive, and the amount of increase measured in each trial was proportional to the degree of unattractiveness. This result indicates the availability of NIRS to real-time evaluation of feeling

Visual servoing based on the use of binocular visual space

We propose a simple visual servoing scheme based on the use of binocular visual space. When we use a hand-eye system which has a similar kinematic structure to a human being, we can approximate the transformation from a binocular visual space to a joint space of the manipulator as a linear time-invariant mapping. This relationship makes it possible to generate joint velocities from image observations using a constant linear mapping. This scheme is robust to calibration error, especially to camera turning, because it uses neither camera angles nor joint angles. Some experimental results are also shown to demonstrate the positioning precision remained unchanged despite the calibration error.

Subliminal gaze cues increase preference levels for items in the gaze direction

ABSTRACT Another individual’s gaze automatically shifts an observer’s attention to a location. This reflexive response occurs even when the gaze is presented subliminally over a short period. Another’s gaze also increases the preference level for items in the gaze direction; however, it was previously unclear if this effect occurs when the gaze is presented subliminally. This study showed that the preference levels for nonsense figures looked at by a subliminal gaze were significantly greater than those for items that were subliminally looked away from (Task 1). Targets that were looked at by a subliminal gaze were detected faster (Task 2); however, the participants were unable to detect the gaze direction (Task 3). These results indicate that another individual’s gaze automatically increases the preference levels for items in the gaze direction without conscious awareness.