Department Publications

The structure and camera pose obtained using multiple view geometry based techniques cannot readily be used for robot localization and mapping. This is due to the fact that the structure and pose obtained relate to the actual environment and motion only up to a transform. In this paper, a method to localize the robot using monocular vision is presented. The assumptions are that the initial pose of the robot is known and that five or more landmarks (true, world points) can be identified. If two or more dissimilar views of at least five non coplanar feature points are initially available, subsequent robot locations with respect to the landmarks in view can be established. The exploration of the environment can then take place incorporating new feature points as the robot moves and successive images are acquired. The feature points which are no longer present in the field of view have to be handled along with the occluded …

In this work, we have taken the first step towards the creation of a computerized seeing-eye guide dog. The system we presented extends the development of assistive technology for the visually impaired into a new area: object tracking and visual servoing. The system uses computer vision to provide a kind of surrogate sight for the human user; sensing information from the environment and communicating it through haptic signalling. Our proof-of concept prototype is a low-cost wearable system which uses a colour camera to analyze a scene and recognize a desired object, then generate tactile cues to the wearer to steer his or her hand towards the object. We have proved the system in trials with random users in an unstructured environment.

The simultaneous localization and map-building (SLAM) problem of robots with Extended Kalman Filter (EKF) framework were studied. Two types of sensing systems, ultrasound and computer vision, were mounted on the robot to perceive the environment so as to simultaneously localize the robot. The Kalman Filter (KF) is a linear, discrete-time, finite dimensional system with recursive structure that makes a digital computer well suited for its implementation. EKF provides a real-time solution to the navigation problem and to on-going estimation of the uncertainty acquired from vehicle motion and landmark observation.

In this paper the design and implementation of a microprocessor for motion control for a Mobile Stereo Camera Platform for Active Vision, is presented. The Stereo Camera Platform has seven degrees of freedom which can simulate neck and eye movements of humans. The microprocessor interprets the instructions given by the user, does the relevant calculations and drives the seven degrees of freedom of the camera platform. The microprocessor was implemented on FPGA using Verilog hardware description language.

The performance of nonlinear adaptive filters in modeling devices with mild and moderately strong nonlinearities such as hearing aids was investigated. The existence on nonlinearities in hearing aids and that nonlinear adaptive filters were better suited for hearing aid modeling compared to their linear counterparts with equal number of filter coefficients. The signal to noise ratio improvement in modeling showed improvements in the range of 5% to 50%. The results suggested that as the nonlinearity of the device becomes stronger, a larger number of nonlinear coefficients should be used.

Object shape and camera motion can be recovered from a sequence of images using a set of feature point correspondences. This is known as the structure from motion problem and the factorization method is the most widely applied solution due to its stability and robustness. This paper describes a method of employing geometrical features available in a scene, in the form of straight lines, in a factorizationbased structure from motion application. The effects of inaccuracies of feature data can be reduced by constraining the reconstructed features corresponding to the points forming straight lines. Our main contribution in this paper is the use of such geometric features to refine the shape recovery using the current advancements in the factorization method. Reconstructed features are mapped to straight lines and the measurement matrix containing image feature data is updated with the adjusted data. This increases …

5.1 Discussion: One of the most cumbersome and difficult problems associated with obtaining solutions for electromagnetic integral equations has been the manipulation of large matrices resulting from numerical methods such as MoM. Unfortunately, such situations are unavoidable in practical problems where the analysis (such as electro-magnetic wave scattering or radiation characteristics) has to be made in respect of objects of complex shapes and sizes. As mentioned in the introductory chapter, several techniques have been developed over the years in order to address this problem. Objective of this research work has been, to investigate the possibility of addressing the above-mentioned problem through wavelet transform techniques that started gaining popularity among the research community over a decade ago. Though there is evidence that wavelet transform techniques have been invented in early 20t h …

In today's competitive and fast-changing telecom industry, most professionals find themselves in the difficult situation of having to sacrifice keeping on top of the latest technology because they are striving to meet another round of high-pressure deadlines. Essentials of Modern Telecommunications Systems offers you a solution to this problem, helping you quickly coming up to speed with the latest advances in your field. By cutting out arcane mathematics and management-speak jargon, it focuses on the essentials you need for rapidly understanding and mastering the latest implementation and development techniques. It provides the complete systems picture from semiconductors to end-to-end networking.

Effective training is essential for human teleoperators to deliver satisfactory performance in actual tasks. Teleoperation is naturally a very difficult task due to the absence of naked-eye vision that cripples the cognitive behavior of the remote operator. Camera vision somehow is not a satisfactory substitution. However, training with naked-eye vision feedback may help human teleoperators to learn how to deliver satisfactory performance when they actually interact with camera vision. This study was carried out to further investigate this hypothesis, and to quantitatively supplement it with experimental proofs. For this cause, the recently built telerobotic test-bed between KAIST (Korea) and Saga University(Japan) was reshaped to a telerobotic mini-golf system, which is the trial experiment in this study. The performance of the players with and without naked-eye training was compared and quantitatively evaluated. The …

This paper discusses the safety assurance, capability features, and user-friendliness of Internet-based telerobotics, in the sense that how these features could be incorporated in order to enhance teleoperator performance. A comprehensive set of safety features are incorporated to the interface to screen and accept only the safe commands from the remote operator while discarding risky commands. A laser pointer is used to help remote operator in perceiving self-location and navigation, whereas orientation control has been completely automated and synchronized to the position commands of the teleoperator. The effectiveness of these features has been demonstrated by playing telerobotic mini-golf.

This paper describes the design and implementation techniques of a generic Internet-based telerobotic system. The purpose is to make available the precious technical information and hands-on experience of the authors for the research community. The paper is based on the telerobotics system that the authors recently implemented between KAIST, Korea and Saga University, Japan. In its current functionality, two control modes: high-level supervisory control and low-level supervisory control are explored demonstrating their merits and demerits.

Focus of attention is often attributed to biological vision system where the entire field of view is first monitored and then the attention is focused to the object of interest. We propose using a similar approach for object recognition in a color image sequence. The intention is to locate an object based on a prior motive, concentrate on the detected object so that the imaging device can be guided toward it. We use the abilities of the intelligent image analysis framework developed in our laboratory to generate an algorithm dynamically to detect the particular type of object based on the user's object description. The proposed method uses color clustering along with segmentation. The segmented image with labeled regions is used to calculate the shape descriptor parameters. These and the color information are matched with the input description. Gaze is then controlled by issuing camera movement commands as …

A telerobotic test-bed has recently been built between KAIST (Korea) and Saga University (Japan). This paper presents its first research work on investigating the interactive learning performance of human teleoperators. For this purpose, the telerobotic test-bed was re-shaped to a telerobotic golf system. Eleven players were participated, and their interactive performance with the telerobot was carefully analyzed for the errors and skills that they demonstrated. It was observed that human teleoperators first try to avoid errors that they did in the previous trials, and then make efforts to explore new skills. It was also experienced that simple task oriented design features and their coordination could significantly improve telerobotic system performance without making it to an excessively sophisticated shape. Interactive learning with naked-eye vision was compared with that of camera vision, and an effective training procedure for human teleoperators was revealed. Some simple, yet appropriate techniques have also been identified that significantly enhance the performance of human teleoperators.

This Paper describes the implementation of a verification system that uses palm geometry to verify the identity of an individual. Palm geometry is a biometric scheme that uses the shape of the hand to confirm the identity of an individual.

This paper presents an effective trajectory planning algorithm for industrial robot manipulators. Given the end-effector trajectory in Cartesian space, together with the relevant constraints and task specifications, the proposed method is capable of planning the optimum endeffector trajectory. The proposed trajectory planning algorithm considers the joint acceleration limit, end-effector velocity limits, and trajectory allowance. A feedforward compensator is also incorporated in the proposed algorithm to counteract the delay in joint dynamics. The algorithm is carefully designed so that it can be directly adopted with the existing industrial manipulators. The proposed algorithm can be easily programmed for various tasks given the specifications and constraints. A three-dimensional test trajectory was planned with the proposed algorithm and tested with the Performer MK3s industrial manipulator. The results verified effective manipulator performance within the constraints.

A new pole selection method for feedforward compensators of mechatronic servo systems is presented in this paper. It is necessary to have the system poles located at desirable positions on the s-plane in order to realize better servoing performance. However, selection of new poles is not a straightforward problem and in most industrial mechatronic systems, it has been a mere cut-and-dry procedure. In this research, feedforward compensator poles are related to the control input, and a criterion was developed to determine the desirable poles that improve the control input within its limits. This method was developed for the second-order model and it was simulated and experiments were performed with the Performer MK3s articulated industrial robot manipulator. Some attractive results have been obtained with the new method.

This paper describes the design and implementation techniques of a generic Internet based telerobotic system. The purpose is to make precious technical information and hands-on experience of the authors widely available for the research community. The paper is based on the telerobotics system that the authors recently implemented between KAIST and Saga University, Japan. In its current functionality, two control modes can be exercised; high-level supervisory control, and low-level supervisory control.

The thesis presents the development of a simple technique for remote reading of utility meters using the low voltage power distribution network. Remotely reading electricity, gas and water meters have distinct advantages over traditional metering methods. Several communication technologies have been designed and implemented for this purpose using wireless techniques, telephone lines, power transmission and distribution lines. In this study, the last one has been selected as the basis for the development of a remote meter reading system applicable to Sri Lanka.

This thesis focuses on trajectory planning for industrial robot manipulators. It describes the existing problem of trajectory planning and proposes an appropriate solution. The proposed solution has been devised, implemented and verified for effective functionality. Trajectory planning in this context is the process of planning time-based joint position trajectories for a desired end-effector motion. It needs to consider all relevant constraints of the manipulator and given task specifications, because the final end-effector performance totally depends on the way the joint trajectories are planned. However, most trajectory planners in industrial robotics, even today, have adapted the technique of direct sampling of the desired end-effector motion, and transform such Cartesian positions to joint space using inverse kinematics. Then, the planned joint trajectories are simulated to check if they are realizable within the constraints. It is also inspected if the given task specifications are fulfilled sufficiently. Planned end-effector trajectory is iteratively adjusted by trial-and-error, until an optimum trajectory is obtained. This process has many demerits and it is therefore necessary to develop an appropriate trajectory planning algorithm which has provisions to consider constraints and task specifications in planning end-effector trajectories. It should also be generally applicable to industrial manipulators. Through constant collaboration with Yaskawa Robotics Inc., the major considerations of trajectory planning were identified as being: 1. trajectory allowance, 2. sharp corners, 3. joint acceleration limit, 4. assigned end-effector velocity, 5. jerk reduction, and 6. delay dynamics …

Abstract< BR> Ⅰ. INTRODUCTION< BR> Ⅱ. MOTION PLANNING AND CONTROL OF ROBOT< BR> Ⅲ. TELEOPERATION AND SUPERVISORY CONTROL< BR> Ⅳ. WELFARE TELEROBOTIC SYSTEM< BR> Ⅴ. RESULTS AND DISCUSSION< BR> Ⅵ. CONCLUSION< BR> ACKNOWLEDGEMENTS< BR> REFERENCES< BR> APPENDIX: BASIC STEPS OF MOTION PLANNING< BR>

Addresses the trajectory tracking problem of industrial robot manipulators, at the corners of a Cartesian three-dimensional trajectory. The goal is to determine the maximum tangential velocity of the end-effector as it traverses a circular arc at a trajectory corner while avoiding joint acceleration saturation. The proposed method first derives the relationship between end-effector velocity and joint accelerations, and then develops a criterion to determine maximum tangential velocity so that only one joint marginally reaches its acceleration limit at a single point on the circular arc. The method was successfully experimented with, and improved performance has been demonstrated.

This research proposes a supervisory control scheme for industrial telemanipulators. The final goal is to devise a control methodology for the effective teleoperation of industrial robot manipulators. Supervisory control is utilized as the base of the control methodology, in that the remote supervisor (human operator) communicates only the important task parameters to the local controller, over the Internet. Local controller plans the optimum trajectory considering supervisor instructions and local constraints, and finally controls the telemanipulator. Reference positions of the desired end-effector trajectory, assigned end-effector speed, working precision, and joint acceleration limits are the important task parameters communicated by the remote supervisor. Local controller considers such specifications in its trajectory planning algorithm. The proposed supervisory control scheme was successfully devised and experimented between the Department of Advanced Systems Control Engineering, Saga University (ASCESU) and Kurume National College of Technology (KNCT).