Showing papers by "Takeo Kanade published in 1985"

Stereo by Intra- and Inter-Scanline Search Using Dynamic Programming

Abstract: This paper presents a stereo matching algorithm using the dynamic programming technique. The stereo matching problem, that is, obtaining a correspondence between right and left images, can be cast as a search problem. When a pair of stereo images is rectified, pairs of corresponding points can be searched for within the same scanlines. We call this search intra-scanline search. This intra-scanline search can be treated as the problem of finding a matching path on a two-dimensional (2D) search plane whose axes are the right and left scanlines. Vertically connected edges in the images provide consistency constraints across the 2D search planes. Inter-scanline search in a three-dimensional (3D) search space, which is a stack of the 2D search planes, is needed to utilize this constraint. Our stereo matching algorithm uses edge-delimited intervals as elements to be matched, and employs the above mentioned two searches: one is inter-scanline search for possible correspondences of connected edges in right and left images and the other is intra-scanline search for correspondences of edge-delimited intervals on each scanline pair. Dynamic programming is used for both searches which proceed simultaneously: the former supplies the consistency constraint to the latter while the latter supplies the matching score to the former. An interval-based similarity metric is used to compute the score. The algorithm has been tested with different types of images including urban aerial images, synthesized images, and block scenes, and its computational requirement has been discussed.

Parameter identification of robot dynamics

Abstract: This paper presents algorithms for identifying parameters of multi-degrees-of-freedom robotic arm. First, we outline the fundamental properties of the Newton-Euler formulation of robot dynamics from the view point of parameter identification. We then show that the Newton-Euler model which is nonlinear in some of dynamic parameters can be transformed into the equivalent model which is linear in dynamic parameters. We develop both on-line and off-line parameter estimation procedures. To illustrate our approach, we identify the dynamic parameters of the cylindrical robot, and the three degree-of-freedom positioning system of the CMU Direct-Drive Arm II.

First results in robot road-following

Abstract: The new Carnegie Mellon Autonomous I and Vehicle group has produced the first demonstrations of road following robots. In this paper we first describe the robots that are part of the CMU Autonomous Land Vehicle project. We next describe the vision system of the CMU ALV. We then present the control algorithms, including a simple and stable control scheme for visual servoing. Finally we discuss our plans for the future.

Stereo by two-level dynamic programming

Abstract: This paper presents a stereo algorithm using dynamic programming technique. The stereo matching problem, that is, obtaining a correspondence between right and left images, can be cast as a search problem. When a pair of stereo images is rectified, pairs of corresponding points can be searched for within the same scanlines. We call this search intra-scanline search. This intra-scanline search can be treated as the problem of finding a matching path on a two dimensional (2D) search plane whose axes are the right and left scanlines. Vertically connected edges in the images provide consistency constraints across the 2D search planes. Inter-scanline search in a three-dimensional (3D) search space, which is a stack of the 2D search planes, is needed to utilize this constraint. Our stereo matching algorithm uses edge-delimited intervals as elements to be matched, and employs the above mentioned two searches: one is inter-scanline search for possible correspondences of connected edges in right and left images and the other is intra-scanline search for correspondences of edge-delimited intervals on each scanline pair. Dynamic programming is used for both searches which proceed simultaneously in two levels: the former supplies the consistency constraints to the latter while the latter supplies the matching score to the former. An interval-based similarity metric is used to compute the score.

Optical navigation by the method of differences

Abstract: The method of differences refers to a technique for image matching that uses the intensity gradient of the image to iteratively improve the match between the two images. Used in an iterative scheme combined with image smoothing, the method exhibits good accuracy and a wide convergence range. In this paper we show how the technique ran be used to directly solve for the parameters relating two cameras viewing the same scene. The resulting algorithm can be used for optical navigation, which has applications in robot arm guidance and autonomous roving vehicle navigation. Because of the regular structure of the algorithm, the prospects of carrying it out with specialpurpose hardware for real-time control of a robot seem good. We present experimental results demonstrating the accuracy and range of convergence that can be expected from the algorithm.

Autonomous scene description with range imagery

Abstract: This paper presents a program to produce object-centered 3-dimensional descriptions starting from point-wise 3D range data obtained by a light-stripe rangefinder. A careful geometrical analysis shows that contours which appear in light-stripe range images can be classified into eight types, each with different characteristics in occluding vs occluded and different camera/illuminator relationships. Starting with detecting these contours in the iconic range image, the descriptions are generated moving up the hierarchy of contour, surface, object, to scene. We use conical and cylindrical surfaces as primitives. In this process, we exploit the fact that coherent relatinships, such as symmetry, and being coaxial, which are present among lower-level elements in the hierarchy allow us to hypothesize upper-level elements. The resultant descriptions are used for matching and recognizing objects. The analysis program has been applied to complex scenes containing cups, pans, and toy shovels.

Development of CMU Direct-Drive Arm II

Abstract: The CMU Direct Drive Arm II (DD II) is the second direct-drive arm designed and constructed at the Robotics Institute, Carnegie Mellon University. It is an electric 6 degree-of-freedom robot, in which all of the joints are of direct drive construction. Featuring high performance Samarium Cobalt magnet brushless DC motors and light weight aluminum construction, the robot has been designed to have a minimum payload of 2.5 Kg with a maximum transit time of 1 second (corresponding to tip speeds of 4 m/sec). High resolution pancake resolvers are mounted directly to the joint shafts for very accurate feedback. Static accuracy is ±0.1 mm. Taking advantage of the dynamic simplicity inherent in direct drive design, the controller is capable of dynamic force compensation in real-time. Such a controller can accurately follow a trajectory at very high speeds. In this paper we discuss the design of this new arm, particularly our solutions to the difficulties of practical implementation of direct drive.