A comparative study of feature extraction using PCA and LDA for face recognition

Feature extraction is important in face recognition. This paper presents a comparative study of reature extraction using Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) for face recognition. The evaluation parameters for the study are time and accuracy of each method. The experiments were conducted using six datasets of face images with different disturbance. The results showed that LDA is much better than PCA in overall image with various disturbances. While in time taken evaluation, PCA is faster than LDA

Person Detection, Tracking and Identification by Mobile Robots Using RGB-D Images

This dissertation addresses the use of RGB-D images for six important tasks of mobile robots: face detection, face tracking, face pose estimation, face recognition, person de- tection and person tracking. These topics have widely been researched in recent years because they provide mobile robots with abilities necessary to communicate with humans in natural ways. The RGB-D images from a Microsoft Kinect cameras are expected to play an important role in improving both accuracy and computational costs of the proposed algorithms for mobile robots. We contribute some applications of the Microsoft Kinect camera for mobile robots and show their effectiveness by doing realistic experiments on our mobile robots. An important component for mobile robots to interact with humans in a natural way is real time multiple face detection. Various face detection algorithms for mobile robots have been proposed; however, almost all of them have not yet met the requirements of accuracy and speed to run in real time on a robot platform. In the scope of our re- search, we have developed a method of combining color and depth images provided by a Kinect camera and navigation information for face detection on mobile robots. We demonstrate several experiments with challenging datasets. Our results show that this method improves the accuracy and computational costs, and it runs in real time in indoor environments. Tracking faces in uncontrolled environments has still remained a challenging task be- cause the face as well as the background changes quickly over time and the face often moves through different illumination conditions. RGB-D images are beneficial for this task because the mobile robot can easily estimate the face size and improve the perfor- mance of face tracking in different distances between the mobile robot and the human. In this dissertation, we present a real time algorithm for mobile robots to track human faces accurately despite the fact that humans can move freely and far away from the camera or go through different illumination conditions in uncontrolled environments. We combine the algorithm of an adaptive correlation filter (David S. Bolme and Lui (2010)) with a Viola-Jones object detection (Viola and Jones (2001b)) to track the face. Furthermore,we introduce a new technique of face pose estimation, which is applied after tracking the face. On the tracked face, the algorithm of an adaptive correlation filter with a Viola-Jones object detection is also applied to reliably track the facial features including the two external eye corners and the nose. These facial features provide geometric cues to estimate the face pose robustly. We carefully analyze the accuracy of these approaches based on different datasets and show how they can robustly run on a mobile robot in uncontrolled environments. Both face tracking and face pose estimation play key roles as essential preprocessing steps for robust face recognition on mobile robots. The ability to recognize faces is a crucial element for human-robot interaction. Therefore, we pursue an approach for mobile robots to detect, track and recognize human faces accurately, even though they go through different illumination conditions. For the sake of improved accuracy, recognizing the tracked face is established by using an algorithm that combines local ternary patterns and collaborative representation based classification. This approach inherits the advantages of both collaborative representation based classification, which is fast and relatively accurate, and local ternary patterns, which is robust to misalignment of faces and complex illumination conditions. This combination enhances the efficiency of face recognition under different illumination and noisy conditions. Our method achieves high recognition rates on challenging face databases and can run in real time on mobile robots. An important application field of RGB-D images is person detection and tracking by mobile robots. Compared to classical RGB images, RGB-D images provide more depth information to locate humans more precisely and reliably. For this purpose, the mobile robot moves around in its environment and continuously detects and tracks people reliably, even when humans often change in a wide variety of poses, and are frequently occluded. We have improved the performance of face and upper body detection to enhance the efficiency of person detection in dealing with partial occlusions and changes in human poses. In order to handle higher challenges of complex changes of human poses and occlusions, we concurrently use a fast compressive tracker and a Kalman filter to track the detected humans. Experimental results on a challenging database show that our method achieves high performance and can run in real time on mobile robots

Symbiotic interaction between humans and robot swarms

Comprising of a potentially large team of autonomous cooperative robots locally interacting and communicating with each other, robot swarms provide a natural diversity of parallel and distributed functionalities, high flexibility, potential for redundancy, and fault-tolerance. The use of autonomous mobile robots is expected to increase in the future and swarm robotic systems are envisioned to play important roles in tasks such as: search and rescue (SAR) missions, transportation of objects, surveillance, and reconnaissance operations. To robustly deploy robot swarms on the field with humans, this research addresses the fundamental problems in the relatively new field of human-swarm interaction (HSI). Four groups of core classes of problems have been addressed for proximal interaction between humans and robot swarms: interaction and communication; swarm-level sensing and classification; swarm coordination; swarm-level learning. The primary contribution of this research aims to develop a bidirectional human-swarm communication system for non-verbal interaction between humans and heterogeneous robot swarms. The guiding field of application are SAR missions. The core challenges and issues in HSI include: How can human operators interact and communicate with robot swarms? Which interaction modalities can be used by humans? How can human operators instruct and command robots from a swarm? Which mechanisms can be used by robot swarms to convey feedback to human operators? Which type of feedback can swarms convey to humans? In this research, to start answering these questions, hand gestures have been chosen as the interaction modality for humans, since gestures are simple to use, easily recognized, and possess spatial-addressing properties. To facilitate bidirectional interaction and communication, a dialogue-based interaction system is introduced which consists of: (i) a grammar-based gesture language with a vocabulary of non-verbal commands that allows humans to efficiently provide mission instructions to swarms, and (ii) a swarm coordinated multi-modal feedback language that enables robot swarms to robustly convey swarm-level decisions, status, and intentions to humans using multiple individual and group modalities. The gesture language allows humans to: select and address single and multiple robots from a swarm, provide commands to perform tasks, specify spatial directions and application-specific parameters, and build iconic grammar-based sentences by combining individual gesture commands. Swarms convey different types of multi-modal feedback to humans using on-board lights, sounds, and locally coordinated robot movements. The swarm-to-human feedback: conveys to humans the swarm's understanding of the recognized commands, allows swarms to assess their decisions (i.e., to correct mistakes: made by humans in providing instructions, and errors made by swarms in recognizing commands), and guides humans through the interaction process. The second contribution of this research addresses swarm-level sensing and classification: How can robot swarms collectively sense and recognize hand gestures given as visual signals by humans? Distributed sensing, cooperative recognition, and decision-making mechanisms have been developed to allow robot swarms to collectively recognize visual instructions and commands given by humans in the form of gestures. These mechanisms rely on decentralized data fusion strategies and multi-hop messaging passing algorithms to robustly build swarm-level consensus decisions. Measures have been introduced in the cooperative recognition protocol which provide a trade-off between the accuracy of swarm-level consensus decisions and the time taken to build swarm decisions. The third contribution of this research addresses swarm-level cooperation: How can humans select spatially distributed robots from a swarm and the robots understand that they have been selected? How can robot swarms be spatially deployed for proximal interaction with humans? With the introduction of spatially-addressed instructions (pointing gestures) humans can robustly address and select spatially- situated individuals and groups of robots from a swarm. A cascaded classification scheme is adopted in which, first the robot swarm identifies the selection command (e.g., individual or group selection), and then the robots coordinate with each other to identify if they have been selected. To obtain better views of gestures issued by humans, distributed mobility strategies have been introduced for the coordinated deployment of heterogeneous robot swarms (i.e., ground and flying robots) and to reshape the spatial distribution of swarms. The fourth contribution of this research addresses the notion of collective learning in robot swarms. The questions that are answered include: How can robot swarms learn about the hand gestures given by human operators? How can humans be included in the loop of swarm learning? How can robot swarms cooperatively learn as a team? Online incremental learning algorithms have been developed which allow robot swarms to learn individual gestures and grammar-based gesture sentences supervised by human instructors in real-time. Humans provide different types of feedback (i.e., full or partial feedback) to swarms for improving swarm-level learning. To speed up the learning rate of robot swarms, cooperative learning strategies have been introduced which enable individual robots in a swarm to intelligently select locally sensed information and share (exchange) selected information with other robots in the swarm. The final contribution is a systemic one, it aims on building a complete HSI system towards potential use in real-world applications, by integrating the algorithms, techniques, mechanisms, and strategies discussed in the contributions above. The effectiveness of the global HSI system is demonstrated in the context of a number of interactive scenarios using emulation tests (i.e., performing simulations using gesture images acquired by a heterogeneous robotic swarm) and by performing experiments with real robots using both ground and flying robots