Jaeyeon Lee

A Non-Cooperative User Authentication System in Robot Environments

For intelligent service robots, it is essential to recognize users in order to provide appropriate services to a correctly authenticated user. However, in robot environments in which users freely move around the robot, it is difficult to force users to cooperate for authentication as in traditional biometric security systems. This paper introduces a user authentication system that is designed to recognize users who are unconscious of a robot or of cameras. In the proposed system, biometrics and semi-biometrics are incorporated to cope with the limited applicability of traditional authentication techniques. Semi-biometrics indicates a set of features useful for discriminating persons, but only in the interested group of persons and in the interested frame of time. As a representative semi-biometric feature, body height and color characteristics of clothes are investigated. In particular, a novel method to measure body height with single camera is proposed. In addition, by incorporating tracking functionality, the system can maintain the user status information continuously, which is useful not only for recognition but also for finding a designated person.

A vision-based user authentication system in robot environments by using semi-biometrics and tracking

The user authentication problem is discussed in the context of robot environments. Although authentication is indispensable for useful robot services, the traditional approaches that have been applied in strictly regulated environments cannot be applied as they are when both the robot and humans are freely moving around. In this paper, a new authentication system redesigned to be adapted to robot environments is described. In the proposed system, semi-biometrics and user tracking are incorporated to cope with the limited applicability of traditional authentication techniques. Semi-biometrics indicates a set of features useful for discriminating persons, but only in interested group of persons and in interested frame of time. As a representative semi-biometric feature, body height and color characteristics of the clothes are investigated. Especially, a novel method to measure body height with single camera is proposed. Also by incorporating tracking functionality, the system could maintain the user status information continuously, which is useful not only for recognition but also for finding a designated person.

Design and Path Planning for a Spherical Rolling Robot

Several designs for a spherical rolling robot have been suggested and some of them were implemented. The kinematics and dynamics study as well as the path planning for the rolling robot are based on the assumption that the deterministic model describes the actual rolling robot successfully. However, due to the high mobility of the sphere, the stochastic behavior is obviously observed. In this paper, we first build a rolling robot to confirm the stochasticity. The robot is actuated by a mass-shifting mechanism where an unbalanced weight inside the spherical robot is rotated by two motors, and the imbalance induced by the weight makes the robot roll. After confirming that this actual rolling robot shows the stochastic behavior, we propose a path planning method for the spherical robot rolling on the plane. The path-of-probability method is applied to generate the most probable path from starting location to destination. This planning method uses the stochasticity of the system to produce the probability density function, and generates the piece-wise short steps for the robot move, which construct the whole trajectory that the robot should follow.© 2013 ASME

A probability-based path planning method using fuzzy logic.

In this paper, we improve the path-of-probability (POP) algorithm to generate better and smoother paths for robotic systems. The POP algorithm generates a full path with the maximum probability to reach a target. Although the POP algorithm has been successfully applied to path generation of robotic systems, it has the limit that the intermediate paths are generated using a finite and small number of candidate paths. This results in non-smooth (or zigzag pattern) paths which are not desirable for practical use. In addition, this approach sometimes fails to generate a path that reaches a target. This can be overcome by increasing the number of candidate paths, but it increases the computation time too. To improve the POP method, we use a fuzzy logic. The fuzzy logic enables us to obtain a continuous set for the intermediate paths from the discrete candidate paths. By applying it, smoother paths from the starting point to the target can be obtained directly without any additional path smoothing because the intermediate paths are chosen from a continuous set. Fundamentally, the fuzzy logic makes a mapping from a finite and discrete set of candidate paths to a continuous set of paths. We apply the proposed method to path planning for a two wheeled robot and a flexible needle. The simulation results confirm the performance of the proposed approach.

Insertion planning for steerable flexible needles reaching multiple planar targets

In this paper, we propose a new insertion plan for steerable flexible needles with which we can target multiple locations in the plane with a single entry point (i.e. port). The method is developed based on the observation that multiple locations can be reached by a flexible needle through insertion, partial retraction, rotation, and re-insertion of the needle. We show that in 2D space this problem can be solved using a geometric relationship between multiple tangent circles. Specifically we find a needle insertion point, a corresponding insertion direction and lengths for insertion and retraction with which we can generate the optimal needle trajectory that reaches two or three planar targets with the minimum tissue damage. This minimization problem is solved using exhaustive search of a cost function on the 1D bounded domain. We build a prototype of a needle insertion system and develop C#-based software to compute the optimal needle paths and perform the planned insertion as an open-loop controller. Finally, actual insertion examples are presented.

Integrated Fire Monitoring System Based on Wireless Multi-Hop Sensor Network and Mobile Robot

Network technology has been developed rapidly for digital service in these days. ZigBee, one of the IEEE 802.15.4 protocols, supporting local communication has become the core technology in the wireless network area. In this paper we designed an integrated fire monitoring system using a mobile robot and the ZigBee sensor nodes which are deployed to monitor fires. When a fire breaks out, the image information of the scene of a fire is transmitted by an autonomous mobile robot and we also monitor the current position of the robot. Furthermore, the data around the place where the fire breaks out and the positions of the sensor nodes can be transmitted to a server via the multi-hop communication in the real time.

Dead-reckoning for a two-wheeled mobile robot on curved surfaces

Recently various kinds of tasks such as the inspections on the curved wall of a vessel are performed by mobile robots. In those cases, the robot has to travel on curved surfaces along the prespecified path and has to know its current position for the successful accomplishment of the tasks. In this paper, we propose a dead-reckoning formula for a two-wheeled mobile robot moving on a curved plane, and illustrate the formula with examples for cylindrical surfaces. The performance of the proposed algorithm will be analyzed through a series of experiments by the magnet wheeled mobile robot developed in our laboratory.

Robot design for bidirectional locomotion induced by vibration excitation

In this paper we design a robot that can move forward and backward based on the vibration excitation. The proposed design enables the robot to locomote on the horizontal surface using the vibration excitation that is perpendicular to the locomotion direction. The bidirectional locomotion is achieved, and the direction of motion is determined by the vibration frequency. This new type of robot is useful for the unconventional environment where complex moving mechanisms cannot be applied to the robots such as medical, small pipeline, and underwater vehicle applications. To this end, two springs with different stiffness are perpendicularly connected and support the main body of the robot. The dynamic response of this nonlinear system to the vibration enables the robot to walk forward and backward depending on the vibration frequency. The numerical simulation of this system and the experiments with actual hardware design verify the proposed approach.

Integrating Evidences of Independently Developed Face and Speaker Recognition Systems by Using Discrete Probability Density Function

User recognition is one of the most fundamental functionalities for intelligent service robots. However, in robot applications, the conditions are far severer compared to the traditional biometric security systems. The robots should be able to recognize users non-intrusively, which confines the available biometric features to face and voice. Also, the robots are expected to recognize users from relatively afar, which inevitably deteriorates the accuracy of each recognition module. In this paper, we tried to improve the overall accuracy by integrating the evidences issued by independently developed face and speaker recognition modules. Each recognition module exhibits different statistical characteristics in representing its confidence of the recognition. Therefore, it is essential to transform the evidences to a normalized form to integrate the results. This paper introduces a novel approach to integrate mutually independent multiple evidences to achieve an improved performance. Typical approach to this problem is to model the statistical characteristics of the evidences by well-known parametric form such as Gaussian. Using Mahalanobis distance is a good example. However, the characteristics of the evidences often do not fit into the parametric models, which results in performance degradation. To overcome this problem, we adopted a discrete PDF that can model the statistical characteristics as it is. To confirm the validity of the proposed method, we used a multi-modal database that consists of 10 registered users and 550 probe data. Each probe data contains face image and voice signal. Face and speaker recognition modules are applied to generate respective evidences. The experiment showed an improvement of 11.27% in accuracy compared to the individual recognizers, which is 2.72% better than the traditional Mahalanobis distance approach.

ViMbot: Design and control of a new magnet robot actuated by an external vibrating magnetic field

This paper presents a design, a control scheme, and experiments for a new vibrating magnet robot (ViMbot). Permanent magnets in the new robot vibrate due to an external vibrating magnetic field. The vibration motion of the robot induces the locomotion of the robot. The vibratory dynamic response of the ViMbot is heavily dependent on the frequency of the vibration. This paper shows that the direction of the robot locomotion can be controlled by the vibration frequency of the external magnetic field. To achieve the distinct dynamic responses depending on the vibration frequency, three acrylic plates with different torsional stiffness are attached at three sides of the triangle-shaped ViMbot and then a magnet is attached to each plate. A strategy to find the special frequencies inducing locomotion and associated experiments with the ViMbot are presented. Control experiments for the ViMbot using the special frequencies are also presented. Because the proposed robot is actuated by an external energy source, the robot can move without traditional actuation components such as motors with batteries. This new design concept allows us to miniaturize the proposed robot.