A navigation system developed for an omni-directional wheeled mobile robot, called the Omnibot, is presented. This system is developed to enable the Omnibot to autonomously navigate, in a collision-free manner, along predefined paths in indoor structured office or factory-like environments. The navigation system is composed of four integrated subsystems: localization, path- following, velocity control, and obstacle detection. The path-following subsystem is responsible for driving the Omnibot along a given path based on feedback about its location relative to its environment. A localization system that uses a combination of odometry and a novel indoor GPS-like system provides the necessary estimates of the Omnibot's position and orientation (i.e., pose). Using the pose updates from the localization subsystem, the path-following subsystem is able to compute motion commands to drive the Omnibot along the path. Execution of these motion commands is performed by the velocity control subsystem, which uses feedback control to regulate the angular velocities of the motors driving the Omnibot's wheels to produce the required motion of the robot. To ensure collision-free navigation, the Omnibot is equipped with an array of infrared distance sensors for detecting obstacles around its perimeter. Interaction between a human operator and the Omnibot is facilitated with a user-control interface running on a remote workstation. The interface allows the operator to visualize the Omnibot's location within a 3D model of its indoor workspace and provides a means to input commands. Testing of the developed system is performed, and the results confirm its e effectiveness at enabling the Omnibot to perform collision-free autonomous navigation in an indoor structured environment. / UOIT

No / A low-profile (λ/43) miniaturized multi-element antenna is presented, which displays vertical polarization with an omni-directional radiation pattern. The antenna uses a logarithmic spiral shape as the main radiating element such that the impedance bandwidth of the antenna is much improved in comparison with both a strip-line square spiral design and a strip-line circular spiral design. The antenna demonstrates stable gain and useful efficiency over the operating frequency band. Significantly, the antenna provides a low profile, omnidirectional pattern in the azimuth plane, polarizes normal to the ground-plane with a 1.2% bandwidth and 0.5 dBi gain.

This thesis presents the design and development of a unique omni-directional platform known as the Omnibot which was built in the Mechatronic and Robotic Systems Laboratory at UOIT. The Omnibot's layout is novel because its drive axes do not intersect with the geometric center of the body, which is typical for omni-directional platforms using segmented omni-directional wheels. This design enables the center of mass to be lower in the design and increases the stability. A suspension system was designed for each of the four wheels to limit vibrations and to ensure contact between the wheels and operating surface. The Omnibot was built to modularly support many systems, including a robot arm, without altering the mechanical design of the frame. Two control modes were developed: local and global. Commands to drive the Omnibot can be received from either a joystick that can be directly interfaced with the controller or with commands that are sent from other systems that are either on or o of the Omnibot. Both control modes require encoder feedback to ensure commanded velocities are being executed as specified. Global control requires feedback from an indoor localization system to determine the Omnibot's pose. Early implementation of the localization system is discussed. An open source robotics software, known as Robot Operating System (ROS) was selected for implementation of the Omnibot systems. ROS serves as a middleware which allows components, such as the localization system and remote desktop, to communicate with each other through a decoupled messaging system. ROS is modular and exible, allowing for easy adaptation of future components. Test results of the Omnibot in operation are presented.

Published Article / Automatic guided vehicles are being used increasingly in a manufacturing environment. Developing a platform that could be easily reconfigured is perhaps a desirable option for a user with low capacity outputs. The research described in this article concentrates on such a vehicle and the development of the actuators and sensors for navigation and proper functionality.

Mobility is something able-bodied people take for granted. Approximately 132,500 people in the United Kingdom have disabilities which permanently confine them to a wheelchair; 40,000 of these require a powered wheelchair. The opportunity to lead a normal life and be accepted as an equal by the able-bodied population is limited by their reduced mobility. As much freedom of movement as possible is therefore crucial for these people. Powered wheelchair users' mobility depends upon the manoeuvrability of the chair. For optimum manoeuvrability a chair must be capable of moving in any direction. Currently no omni-directional powered wheelchairs are commercially available. This thesis describes the design and deVelopment of a powered base unit for a wheelchair, controlled to instantaneously move in any direction. The novelty is principally represented by the innovative design and configuration of four omni-directional roller wheels* (LUMAN wheels) which, when individually controlled, produce the omni-directional movement of the base unit. Further novelty within the design is a set of bi-directional angled roller couplings that simultaneously disengage the wheels from the motors, via a cable linkage mechanism, and simple control system. Mathematical data models illustrate the theoretical performance of the wheel configuration, and a prototype base unit is tested to prove these hypotheses.

Recent work has shown that flow estimation from a pair of images can be formulated as a supervised learning task to be resolved with convolutional neural networks (CNN). However, the basic straightforward CNN methods estimate optical flow with motion and occlusion boundary blur. To tackle this problem, we propose a tiny diagnostic dataset called FlowClevr to quickly evaluate various modules that can use to enhance standard CNN architectures. Based on the experiments of the FlowClevr dataset, we find that a deformable module can improve model prediction accuracy by around 30% to 100% in most tasks and more significantly reduce boundary blur. Based on these results, we are able to design modifications to various existing network architectures improving their performance. Compared with the original model, the model with the deformable module clearly reduces boundary blur and achieves a large improvement on the MPI sintel dataset, an omni-directional stereo (ODS) and a novel omni-directional optical flow dataset.

From the viewpoint of applications, conventional cameras are usually limited in their fields of view. The omni-directional camera has a full range in all directions, which gains the complete field of view. In the past, a moving object can be detected, only when the camera is static or moving with a known speed. If those methods are employed to mobile robots or vehicles, it will be difficult to determine the motion of moving objects observed by the camera. In this paper, we assume the omni-directional camera is mounted on a moving platform, which travels with a planar motion. The region of floor in the omni-directional image and the brightness constraint equation are applied to estimate the ego-motion. The depth information is acquired from the floor image to solve the problem that cannot be obtained by single camera systems. Using the estimated ego-motion, the optical flow caused by the floor motion can be computed. Therefore, comparing its direction with the direction of the optical flow on the image leads to detection of a moving object. Due to the depth information, even if the camera is in the condition that combining translational and rotational motions, a moving object can still be accurately identified.

This thesis describes a method to create local maps from an omni-directional vision system (ODVS) mounted on a mobile robot. Range finding is performed by a structure-from-motion method, which recovers the three-dimensional position of objects in the environment from omni-directional images. This leads to map-making, which is accomplished using certainty grids to fuse information from multiple readings into a two-dimensional world model. The system is demonstrated both on noise-free data from a custom-built simulator and on real data from an omni-directional vision system on-board a mobile robot. Finally, to account for the particular error characteristics of a real omni-directional vision sensor, a new sensor model for the certainty grid framework is also created and compared to the traditional sonar sensor model.

ITC/USA 2009 Conference Proceedings / The Forty-Fifth Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2009 / Riviera Hotel & Convention Center, Las Vegas, Nevada / Most range safety telemetry tracking systems have antenna designs that feature an S-band (2200-2400 MHz) Telemetry Tracking and UHF-Band (400-450 MHz) Command Destruct feed along side an omni-directional antenna. The antennas must have, by design, high angular velocity (w) and acceleration (α) parameters to achieve these tasks. Generally, these parameters are user configurable through software and monitored through BIT (Built In Test) log files. The parameters are nominally set to their maximum values (ie. w=10 deg/sec and α = 15 deg/sec².) Considering the dynamics of a sample satellite launch vs. the ground tracking and omni antennas' combined capabilities, this document analyzes whether the target will stay within the beam.

The focus of this dissertation is on the development and circuit modeling of planar series-fed, linear- and circular-polarized microstrip aperture-coupled antennas and N-element arrays operating in C-band. These arrays were designed to be used as part of airborne or land-based frequency-hopped communication systems. One of the main objectives of this work was to maintain a constant beam angle over the frequency band of operation. In order to achieve constant beam pointing versus frequency, an anti-symmetric series-fed approach using lumped-element circuit models was developed. This series feed architecture also balances the power radiated by each element in the N-element arrays. The proposed series-fed approach was used in the development of four-element series-fed aperture-coupled arrays with 15% 10 dB impedance bandwidth centered at 5 GHz and a gain of 11.5 dB, to construct an omni-directional radiator. Omni-directional radiators with pattern frequency stability are desired in a multitude of applications; from defense in tactical communications, information gathering, and detection of signal of interest to being part of sensors in medical applications. A hexagonal assembly of six series-fed microstrip aperture-coupled four-element arrays was used to achieve the omni-directional radiation with 0.6 dB peak to peak difference across 360˚ broadside pattern and 0.6 dB gain variation at the specific azimuth angle across 15% impedance bandwidth. Given that each of these six arrays can be individually controlled, this configuration allows for individual pattern control and reconfiguration of the omni-directional pattern with increased gain at specific azimuth angles and the ability to form a directional pattern by employing a fewer number of arrays. Incorporating a beam-forming network or power distribution network is also possible. Wide 3 dB circular polarization (CP) bandwidth was achieved without external couplers and via only a single feed with a unique Z-slot aperture-coupled microstrip antenna. A single RHCP Z-slot aperture-coupled antenna has ∼10% CP and 10 dB impedance bandwidth. The series-fed network consisting of lumped elements, open-circuited stubs and transmission lines was subsequently developed to maintain more than 5% CP and 10% 10 dB impedance bandwidth in the series-fed four-element Z-slot aperture-coupled CP array that could also be used for-omni-directional radiation.