Adrian David Cheok

Pervasive games: bringing computer entertainment back to the real world

This article gives an introduction and overview of the field of pervasive gaming, an emerging genre in which traditional, real-world games are augmented with computing functionality, or, depending on the perspective, purely virtual computer entertainment is brought back to the real world.The field of pervasive games is diverse in the approaches and technologies used to create new and exciting gaming experiences that profit by the blend of real and virtual game elements. We explicitly look at the pervasive gaming sub-genres of smart toys, affective games, tabletop games, location-aware games, and augmented reality games, and discuss them in terms of their benefits and critical issues, as well as the relevant technology base.

Human Pacman: a mobile, wide-area entertainment system based on physical, social, and ubiquitous computing

Human Pacman is a novel interactive entertainment system that ventures to embed the natural physical world seamlessly with a fantasy virtual playground by capitalizing on mobile computing, wireless LAN, ubiquitous computing, and motion-tracking technologies. Our human Pacman research is a physical role-playing augmented-reality computer fantasy together with real human–social and mobile gaming. It emphasizes collaboration and competition between players in a wide outdoor physical area which allows natural wide-area human–physical movements. Pacmen and Ghosts are now real human players in the real world, experiencing mixed computer graphics fantasy–reality provided by using the wearable computers. Virtual cookies and actual tangible physical objects are incorporated into the game play to provide novel experiences of seamless transitions between real and virtual worlds. We believe human Pacman is pioneering a new form of gaming that anchors on physicality, mobility, social interaction, and ubiquitous computing.

Touch-Space: Mixed Reality Game Space Based on Ubiquitous, Tangible, and Social Computing

Abstract: This paper presents a novel computer entertainment system which recaptures human touch and physical interaction with the real-world environment as essential elements of the game play, whilst also maintaining the exciting fantasy features of traditional computer entertainment. Our system called ‘Touch-Space’ is an embodied (ubiquitous, tangible, and social) computing based Mixed Reality (MR) game space which regains the physical and social aspects of traditional game play. In this novel game space, the real-world environment is an essential and intrinsic game element, and the human’s physical context influences the game play. It also provides the full spectrum of game interaction experience ranging from the real physical environment (human to human and human to physical world interaction), to augmented reality, to the virtual environment. It allows tangible interactions between players and virtual objects, and collaborations between players in different levels of reality. Thus, the system re-invigorates computer entertainment systems with social human-to-human and human-to-physical touch interactions.

A new torque and flux control method for switched reluctance motor drives

Switched reluctance (SR) motors have an intrinsic simplicity and low cost that make them well suited to many applications. However the motors doubly salient structure and highly nonuniform torque and magnetization characteristics lead to the inability to excite the motor using conventional AC motor waveforms, or apply established AC motor rotating field theory to the motor. Furthermore, high torque ripple is inherent in the motor unless a torque ripple reduction strategy is employed. Thus, control of the motor is difficult and complex compared to other machines. Previous methods of control have fallen into two main categories: those which use a simplified linear model and those which account for the motor saturation. The simplified linear model schemes have the advantage of simplicity and tractability but are inaccurate in most practical SR drives, whereas the nonlinear schemes have the problem of high complexity and computational expensiveness which makes real-time implementation difficult. To overcome these problems, in this paper, a novel control method for the SR motor is derived from analysis of the nonuniform torque characteristics of the motor. The control method applies the philosophy of direct torque control (DTC). Unlike previous direct torque control schemes for the SR motor drive, the new method does not involve short flux patterns, a change of the motor winding configuration, or the use of a bipolar current drive. Thus, the scheme can be conveniently implemented on any normal type of SR motor drive. In addition, the scheme overcomes the problems associated with torque ripple control in the SR motor by regulating the torque output of the motor within a hysteresis band. Furthermore, the scheme is very simple and can be implemented in real-time with low cost microprocessor hardware.

Huggy Pajama: a mobile parent and child hugging communication system

Huggy Pajama is a novel wearable system aimed at promoting physical interaction in remote communication between parent and child. This system enables parents and children to hug one another through a novel hugging interface device and a wearable, hug reproducing pajama connected through the Internet. The hugging device is a small, mobile doll with an embedded pressure sensing circuit that is able to accurately sense varying levels of the range of human force produced from natural touch. This device sends hug signals to a haptic jacket that simulates the feeling of being hugged to the wearer. It features air pockets actuating to reproduce hug, heating elements to produce warmth that accompanies hug, and color changing pattern and accessory to indicate distance of separation and communicate expressions. In this paper, we present the system design of Huggy Pajama.

3D live: real time captured content for mixed reality

We present a complete system for live capture of 3D content and simultaneous presentation in augmented reality. The user sees the real world from his viewpoint, but modified so that the image of a remote collaborator is rendered into the scene. Fifteen cameras surround the collaborator, and the resulting video streams are used to construct a three-dimensional model of the subject using a shape-from-silhouette algorithm. Users view a two-dimensional fiducial marker using a video-see-through augmented reality interface. The geometric relationship between the marker and head-mounted camera is calculated, and the equivalent view of the subject is computed and drawn into the scene. Our system can generate 384 /spl times/ 288 pixel images of the models at 25 fps, with a latency of < 100 ms. The result gives the strong impression that the subject is a real part of the 3D scene. We demonstrate applications of this system in 3D videoconferencing and entertainment.

Augmented reality camera tracking with homographies

To realistically integrate 3D graphics into an unprepared environment, camera position must be estimated by tracking natural image features. We apply our technique to cases where feature positions in adjacent frames of an image sequence are related by a homography, or projective transformation. We describe this transformations computation and demonstrate several applications. First, we use an augmented notice board to explain how a homography, between two images of a planar scene, completely determines the relative camera positions. Second, we show that the homography can also recover pure camera rotations, and we use this to develop an outdoor AR tracking system. Third, we use the system to measure head rotation and form a simple low-cost virtual reality (VR) tracking solution.

High robustness and reliability of fuzzy logic based position estimation for sensorless switched reluctance motor drives

In many applications where motor drives are used, concern. Thus, a major consideration is the reliability of position estimation schemes when sensor less SR motor drive control is employed. Hence, in this paper, the robust of a fuzzy logic based angle estimation algorithm for the switched reluctance motor (SR) motor is described. It is shown using theoretical analysis and experimental results, that by using logic, the angle estimation scheme gains a high level of robustness and reliability. A theoretical and quantitative analysis of the noise and error commonly found in practical motor drives is given, and how this can affect SR motor position estimation. An analysis is also given on the concepts of robustness and reliability. It is shown that the fuzzy logic based scheme is robust to erroneous and noisy signals commonly found in motor drives.

Micro-accelerometer based hardware interfaces for wearable computer mixed reality applications

Human interaction with wearable computers is an important research issue, especially when combined with mixed reality (MR) applications. Natural and non-obtrusive means of interaction calls for new devices, which should be simple to use. This paper considers the design of new interaction hardware, such as a wearable computer pen, a tilt pad, a wand, and a gesture pad designed using accelerometers for such scenarios. The very difficult problem of noise in small hardware accelerometers (in the form of random bias drifts), which seriously impedes its application in position measurement is also examined in detail. Kalman filtering has resulted in improved results, which are presented herewith. The application of accelerometers to design interfaces for use in mixed reality environments is also explained.

Online 6 DOF augmented reality registration from natural features

We present a complete scalable system for 6 DOF camera tracking based on natural features. Crucially, the calculation is based only on pre-captured reference images and previous estimates of the camera pose and is hence suitable for online applications. We match natural features in the current frame to two spatially separated reference images. We overcome the wide baseline matching problem by matching to the previous frame and transferring point positions to the reference images. We then minimize deviations from the two-view and three-view constraints between the reference images and the current frame as a function of camera position parameters. We stabilize this calculation using a recursive form of temporal regularization that is similar in spirit to the Kalman filter. We can track camera pose over hundreds of frames and realistically integrate virtual objects with only slight jitter.