For an evaluation of walking motions, a body acceleration is considered to be an important measure. The reason is that, if the walking motion is stable, the body acceleration usually shows almost periodic patterns, and if not, it does not. Therefore, it is thought that, for an evaluation of crutch walking motions, the crutch user's body acceleration would be required. That is, unstable crutch walks result in aperiodic body accelerations, and it may cause the users falling. In this research, an instruction system of a crutch walking for untrained patients has been developed. The body accelerations are usually measured by acceleration sensors being attached on the walker's body. Therefore, the sensor systems may disturb smooth walking motions. In addition, it is desirable that commonly available sensors can be utilized for measurements of the walker's body accelerations without anything attached on the body. Therefore, in this paper, a novel acceleration measurement method, i.e., a body-part movement-based acceleration measurement method, was proposed for crutch users. For this purpose, several participants' crutch walks were measured by both an optical motion capturing system and an acceleration sensor system, and multiple linear regression analyses were applied for the acceleration data. As a result, an estimation model with the body acceleration was derived.

Up to now, several kinds of walk assisting devices have been developed, and these have been usually used by injured patients. Patients who have their leg injured often use crutches in order to reduce their weight to be borne with their injured leg, because crutches are regarded as familiar devices. However, some patients who were injured by sudden accidents don't know about proper methods to use the crutches, which results in improper usages: the improper usage may cause the patients to fall down, and it sometimes leads to more serious injuries. For these patients, it is effective to evaluate if the patient's method to use the crutches is proper or not based on the measurements of the walk motions in early rehabilitation stage. In addition, the walk motions had better been measured in a simple way rather than using complex measurement devices. In this paper, relationships between improper crutch walk and motions of participant's body parts were discussed, and its result is expected to be utilized to show which body part is most influenced by the improper crutch walk. In crutch walk experiment, motions of participants' thigh, knee and toe, body acceleration and tilting angle of the crutch were measured. As a result, especially, the motion of thigh was most influenced by the improper crutch walk. From this result, it was confirmed that crutch walks can be evaluated by measuring only the motion of thigh. This result may also show that thigh performs a crucial function for preventing falling in crutch walks.

We proposed a synthetic aperture GPR (Ground Penetration Radar) for buried flat-plates. The geometrical conditions of the flat-plates, i.e., the length, the inclination angles, the horizontal positions, and the buried depth are estimated by using a nonlinear least-squares method: the geometrical model-calculated propagation times are fit to the observed ones at all the antenna positions. We carried out some survey experiments to inspect a metallic plate being buried in soil medium, and, furthermore, compared the proposed algorithm with a visual observation-based method. As a result, we confirmed the effectiveness of the proposed algorithm.

When a robot is operated remotely, a monitoring camera is often used. In conventional systems, an operator controls both a robot and a monitoring camera. A camera has to be controlled so that its zooming scale and angle are to be desirable for an operator. Therefore, the automatic control of a camera is necessary for smooth operations of a robot. In this paper, the authors proposed a new algorithm to control a monitoring camera automatically. While an operator sends commands to an operated manipulator via a joystick, a monitoring camera is automatically controlled based on the algorithm where the joystick motion information is ingeniously utilized. Experiments were carried out, and an effectiveness of the proposed algorithm was confirmed

Human beings seem to recognize objects based on a kind of model-matching, i.e., a virtual manipulation on mental images. This paper presents a 3-D object pose estimation method simulating the human recognition scheme. Computer synthesizes not only an edge image but also a shading image from an object model. Then, it matches the two kinds of synthesized images with the inputted images individually by using a non-linear least-squares method, and estimates the pose parameter values. Finally, it chooses the better of the individually estimated poses. Thus, the fusion of the shading and the edge information is achieved. Since the two pieces of information complement each other, this method has the advantage of much higher robustness and accuracy of pose estimation than ordinary model-matching techniques which rely only on geometrical features such as vertices or edges.

Based on model-driven image matching, the 3-D object pose is iteratively estimated. Shading images and edge images are synthesized from an abject model, and are matched, individually, with the input images by using a nonlinear least-squares method. The fusion of the shading and the edge information is achieved choosing the better of the two pieces of image matching.

A simple and useful calibration method for a TV camera with a high-distortion lens is presented. The parameters to be calibrated are effective focal length, one-pixel width on an image plane, image distortion center, and distortion coefficient. A simple-pattern calibration chart composed of parallel straight lines is introduced as a reference for calibration. An ordinary 2D model fitting is decomposed into two 1D model fittings on the column and row of a frame buffer across the image distortion center by ingeniously utilizing the point symmetry characteristic of image distortion. Some parameters with a calibration chart are eliminated by setting up a calibration chart precisely and by utilizing negligibly low distortion near the image distortion center. Thus, the number of unknown parameters to be calibrated is drastically decreased, enabling simple and useful calibration. The effectiveness of the proposed calibration method is confirmed by experimentation.>

The relation between the accuracy of calibrated TV camera parameters and the calibration condition is examined by applying a law of propagation, and the optimal calibration condition is proposed where an iterative method is applied to calibrate the parameter values. Furthermore, the variance of the estimated 3D information is determined quantitatively in the case of optimal calibration condition.>

Noise that replaces, rather than perturbs, a signal is not amenable to the usual approaches of noise removal. Here, multiple images of a stationary scene are used to reduce random obscuration or dropout noise by the following method. For each image coordinate, a gray-level initial histogram is computed over all the images. The initial histograms are averaged for all image coordinates, and for each image coordinate a gray-level histogram corresponding to the object is derived by subtracting the averaged histogram from the initial one. The gray level of the object is obtained from the resulting object histogram. The effectiveness of this method is confirmed through experiments using a scene obscured by air bubbles in a water tank.>