Tomohiko Hayakawa

Real-time high-speed motion blur compensation system based on back-and-forth motion control of galvanometer mirror

We developed a novel real-time motion blur compensation system for the blur caused by high-speed one-dimensional motion between a camera and a target. The system consists of a galvanometer mirror and a high-speed color camera, without the need for any additional sensors. We controlled the galvanometer mirror with continuous back-and-forth oscillating motion synchronized to a high-speed camera. The angular speed of the mirror is given in real time within 10 ms based on the concept of background tracking and rapid raw Bayer block matching. Experiments demonstrated that our system captures motion-invariant images of objects moving at speeds up to 30 km/h.

Visualization of tactile material relationships using sound symbolic words

Although humans can richly perceive variations of tactile textures, the relationships among tactile sensation categories are not clearly generalized. Here we propose a novel method for classifying sensations for tactile textures using onomatopoeic words (sound symbolic words) in Japanese. The method generates a distribution diagram of onomatopoeic words based on subjective impressions of the words, and enables users to arrange and compare the tactile textures on the diagram in two-dimensionally visualized form. We describe two experiments performed to generate the distribution diagram and examine the validity of the diagram.

Supportive training system for sports skill acquisition based on electrical stimulation

A supporting training system using a haptic device is considered to contribute more to motion learning than other stimuli that stimulate the human somatosensory system. However, the apparatus required for haptic stimulation is large, although the output is small. Electrical stimulation has been gaining attention in the field of human interfaces in recent years as a potential solution to this problem. Electrical stimulation is superior to existing haptic interfaces in that a large output can be generated using a few batteries, which can drive muscles to contract. Therefore, in this study, we developed a training system using electrical stimulation. This system teaches the rotation of arms, which is difficult to achieve by means of other haptic stimuli. We confirmed that the form in the rotation direction was successfully modified by using this system. The form was improved by 32% through electrical stimulation during training, and the form correction was achieved via the somatosensory system, which is difficult with the existing method. In addition, we verified that the skill was memorized in a short period of time and retained in the short term.

Trajectory adjustment system for learning based on electrical stimulation

Electrical stimulation is a well-known technology in medicine used for stimulating human muscles that has been applied in rehabilitation. Recently, electrical stimulation has been spotlighted for generating haptic sensations in human interface applications. Existing methods of generating haptic sensations are mainly mechanical. However, electrical stimulation can generate much stronger stimulation than mechanical force generators with the same energy. In this study, we consider applications of electrical stimulation to skill learning. Through simple tasks to learn trajectory, we assessed the learning rate using electrical stimulation compared with learning using vibration.

GPS error range reduction method based on linear kinematic model

GPS is an effective tool to localize robots within an absolute coordinate frame. However, depending on the application, even the accuracy provided by the GPS in an ideal environment might be too low for precise control. In this work we propose a method for reducing the error range of GPS measurements based on an assumption of linear motion. While previous research in this area has mainly improved accuracy using pre-processing and Map-matching, the proposed method makes an assumption of one-dimensional motion, since most vehicle moves linearly, for making corrections. Raw measurements are projected onto a line generated using a method of least squares linear regression. Therefore the error range is reduced to the distance of the intersections of the rail line and the ellipsoid body that indicates the measurement error. Through experiments we demonstrate that the error range reduced at most 15 % at locally compared to the raw measurements. It is possible to apply this method also to other kinematic models, Map-matching algorithms, consumer GPS, and in real-time applications.

Pixel-wise deblurring imaging system based on active vision for structural health monitoring at a speed of 100 km/h

In this paper, we propose a pixel-wise deblurring imaging (PDI) system based on active vision for compensation of the blur caused by high-speed one-dimensional motion between a camera and a target. The optical axis is controlled by back-and-forth motion of a galvanometer mirror to compensate the motion. High-spatial-resolution image captured by our system in high-speed motion is useful for efficient and precise visual inspection, such as visually judging abnormal parts of a tunnel surface to prevent accidents; hence, we applied the PDI system for structural health monitoring. By mounting the system onto a vehicle in a tunnel, we confirmed significant improvement in image quality for submillimeter black-and-white stripes and real tunnel-surface cracks at a speed of 100 km/h.

Precise shape-sensing method using micro pinhole for micro holes (Conference Presentation)

Currently, micro fabrication has gained popularity because of miniaturization and densification of devices. Accordingly, the importance of optical shape measurement to detect processing defects and verify the necessity of re-processing is increasing. On the other hand, conventional optical shape-sensing methods require complicated settings such as strict calibration and liquid immersion, and long examination durations; however, there is a requirement for a rapid examination method. Thus, in this research, we propose an optical shape-measuring method for drilled objects, using the light leakage through holes. Specifically, improved precision can be expected by scanning target holes illuminated by a monochromatic LED from the back with a micro pinhole installed on a high-precision stage, and detecting light using an area camera passing through the pinhole. Images are captured at every scanning step of the stage, and finally, one integrated image is generated. An advantage of this method is that even if the diameter of the pinhole is larger than the minimum step of the stage, the camera can detect the amount of light leakage; hence, a high-precision image can be captured by our method. Moreover, the proposed method reduces the labor required for setup and shortens the examination time because it does not require liquid immersion and strict calibration for each object. Through the experiment, we verified the proposed method using a pinhole having a diameter of 10 μm, and obtained the image of through holes. As future work, the scanning speed could be improved using multi-arrayed micro pinholes.

Real-time high-speed motion blur compensation method using galvanometer mirror for shape sensing of microfabricated objects

In this paper, motion-blur compensation method for micro fabricated objects using a galvanometer mirror with back-and-forth rotation is proposed. Motion-blur compensation is expected to extend exposure time without motion blur because longer exposure time can decrease the intensity of illumination to avoid shape expansion of a target object by heat of illumination. Dealing with this demand, a galvanometer mirror is installed between the target and a 2D high-speed camera, and controls the optical axis of the camera to follow the moving target. Each continuous images are taken during the motion of the stage, and finally taken images are integrated into one image by patching for detecting fabrication error using image processing. The experimental system that consists of a high-speed camera, a galvanometer mirror and a high-precision stage is developed and a 20mm=/s moving drilled silicon nitride sheet having holes of about 40 μm in diameter are lattice-shaped at a pitch of 60 μm is captured without motion blur by using this system. Comparing captured images with still images in diameter, roundness and curvature of the each holes, the effectiveness of this system is validated.

Depth of field extended imaging method based on intensification of time and spatial expansion

Microscopy imaging optics can capture the high-resolution image at a certain focus plane, but the information outside that focal plane will become a blur and the information will be lost. We can adjust the optics stop or manually adjust the focal length, but the resolution will be reduced and it is capable of observing a high speed moving target in vivo. When a transparent plate was placed in front of a camera, the focusing point of the original system would be shifted. We proposed a variable focus system for extending the depth of field of the microscopy imaging system.

Simultaneous position and angle control for outgoing laser beam design using two galvanometer mirrors

In this study, we propose a laser beam pointing method that allows for simultaneous control of position and angle using two commercially available galvanometer mirrors. Two mirrors are placed next to each other. Mathematical calculations show that the outgoing beam angle for the system is defined by the control angles of the two mirrors, and the one-dimensional position of the outgoing beam is defined by the angles of the two mirrors and the distance between their rotational centers. Using a line laser, two galvanometer mirrors, and a camera, we confirmed that the one-dimensional position and angle can be controlled using the proposed method. This method can be used for dynamic fabrication and manufacturing in future.