柴田 昌明

In this paper, we propose a visual tracking method for a moving object without tracking delay. On visual servoing, image-based method with image Jacobian is often taken for target-centering camera motion control because it does not require target's 3D position estimation and is robust to modeling errors and noises. In an ordinary visual servoing approach, it is assumed that the target object would be fixed in the workspace. Therefore, for the purpose of tracking to a moving target, the image errors always exist between the target position and camera optical axis, that is, the visual tracking delay. In our proposed method, the target object's 3D position is estimated with the technique based on triangulation on stereo vision system. Then, the moving velocity is calculated in the camera coordinate frame. The image Jacobian concerns the camera velocity with the target velocity in the image plane. Additionally, the target velocity in 3D workspace is also converted into the velocity in the image plane. The converted velocity compensates the camera velocity to compensate the camera motion delay. This approach enables to achieve non-delayed tracking for moving target.

This paper proposes a way of gait trajectory generation with artificial vector field for stable walking of a biped robot. The tip of the robot on walking can often deviate from the desired trajectory by the disturbances forced by unexpected outside factors. In our approach, though no prepared trajectory is specified a priori, the tip follows the artificial vectors designed in the workspace. Moreover, the prediction simulation is performed on-line. The simulator judges the stability under comparison with the present state and the prediction results, and then the gait parameters are adaptively improved in feedforward for the stable walk. The numerical and physical experimental results show the validity of the proposed method in the continuous walk.

This This paper describes a control method for moving object tracking on an active stereo vision robot. Our developed robot has 3 rotational axes; two are for camera-pan motion and one for base rotation, and then has structural redundancy to track the target object. The aim of our approach is to achieve both requirements of rigid tracking and accurate position estimating, and then the characteristics of each rotational axis are considered form the viewpoint of dynamics. Since the base axis has heavier inertia than the camera axes, the camera-pan motion is preferable to realize rigid tracking in the high gain servoing. On the other hand, the base is required to face to the target to prevent the position estimation accuracy from getting worse, so that the base would turn to the target in the slow response. The former motion is realized in the image-base visual servo control law, while the latter in the mechanical impedance control law, and then these control laws are unified in the proposed method. Additionally, the Kalman filter is introduced for prediction of the target motion. The filter contributes to more precise target position estimation. The validity of our method is confirmed in the physical experimental results.

3自由度を有するステレオビジョンシステムによる追従視のための一制御手法を提案した. 構造的冗長自由度を有するロボットについて動特性を考慮し, 追従視の位置推定精度と追従特性の向上の両立を図った. 定常的には基盤正面およびカメラ光軸に対象をとらえ, 過渡的には各軸の負荷慣性に対応した応答特性を得る動作制御法を導入した. さらに, 対象の動作予見を導入することで良好な実験結果を得た.