MODELING AND PROTOTYPING A MODULAR, LOW-COST COLLISION AVOIDANCE SYSTEM FOR UAVS

Many challenges arise when attempting to use unmanned aerial vehicles (UAVs) in indoor environments, such as the lack of a GPS signal for use in navigation and the smaller margin of error in movements. Typically, those challenges are addressed by using a collision avoidance system. However, most commercially available collision avoidance systems are expensive, limited in suppliers, and are restricted to use on a specific platform. Additionally, some of the collision avoidance systems choose to forego obstacle detection in one or more directions, usually the upward direction. This work proposes that it is possible to develop a custom, low-cost collision avoidance system with modular capabilities, allowing it to be adapted to any UAV platform. The feasibility of the proposed system was determined by creating a single-direction prototype that was implemented on a small quadcopter and tested by flying the quadcopter towards a wall at slow speeds. To develop the system’s control algorithm a model of a quadcopter was built. Two different control algorithms were developed and tested via simulation with the model, and the better performing algorithm was implemented in the prototype. The feasibility of the proposed collision avoidance system is promising with the prototype able to prevent the quadcopter from colliding with a wall. However, further refinement in the methodology and techniques used to develop the system is needed to improve performance and reliability of the system, especially as obstacle detection is added in other directions of motion. Keywords

Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 182, July 1978

This bibliography lists 165 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 1978

Estimation of Thickness and Speed of Sound for Transverse Cortical Bone Imaging Using Phase Aberration Correction Methods: An In Silico and Ex Vivo Validation Study

Delay-and-sum (DAS) beamforming of backscattered echoes is used for conventional ultrasound imaging. Although DAS beamforming is well suited for imaging in soft tissues, refraction, scattering, and absorption, porous mineralized tissues cause phase aberrations of reflected echoes and subsequent image degradation. The recently developed refraction corrected multi-focus technique uses subsequent focusing of waves at variable depths, the tracking of travel times of waves reflected from outer and inner cortical bone interfaces, the estimation of the shift needed to focus from one interface to another to determine cortical thickness (Ct.Th), and the speed of sound propagating in a radial bone direction (Ct.nu(11)). The method was validated previously in silico and ex vivo on plate shaped samples. The aim of this study was to correct phase aberration caused by bone geometry (i.e., curvature and tilt with respect to the transducer array) and intracortical pores for the multi-focus approach. The phase aberration correction methods are based on time delay estimation via bone geometry differences to flat bone plates and via the autocorrelation and cross correlation of the reflected ultrasound waves from the endosteal bone interface. We evaluate the multi-focus approach by incorporating the phase aberration correction methods by numerical simulation and one experiment on a human tibia bone, and analyze the precision and accuracy of measuring Ct.Th and Ct.nu(11). Site-matched reference values of the cortical thickness of the human tibia bone were obtained from high-resolution peripheral computed tomography. The phase aberration correction methods resulted in a more precise (coefficient of variation of 5.7%) and accurate (root mean square error of 6.3%) estimation of Ct.Th, and a more precise (9.8%) and accurate (3.4%) Ct.nu(11) estimation, than without any phase aberration correction. The developed multi-focus method including phase aberration corrections provides local estimations of both cortical thickness and sound velocity and is proposed as a biomarker of cortical bone quality with high clinical potential for the prevention of osteoporotic fractures

A feasability study on guided wave-based robotic mapping

Ultrasonic guided wave imaging techniques have received much attention in recent years for fast screening of large structures. Here we explore the feasibility of Occupancy Grid Mapping (OGM) in order to construct a map of an unknown component for inspection. OGM is a well-established algorithm in robotics, but for the first time we are applying it to Shear Horizontal (SH) guided wave imaging. This approach, in contrast to some existing guided wave-based imaging techniques, would not require prior knowledge of an intact state of the sample. OGM works on the ranges obtained by the Time of Flight (ToF) of the received signals operating in pseudo-pulse-echo mode

Using the piezoelectric backscatter signal for remote sensing of neural signals

In recent studies, various methods to sense neural signals are used and new methods for remote sensing of neural signals are being developed. However, there are still major difficulties in building long-term implantable neural interface systems that can reliably record neural activity and serve as the basis of brain-machine interfaces (BMI). Therefore, this research is conducted to design a remote neural sensing system that is based on modulation of the backscatter signal from a piezoelectric element by the neural signals. The hypothesis is that if the neural signal is detected with a simple amplifier and the output of this amplifier is connected in parallel to a piezoelectric element, the backscattered signal from the piezoelectric element should be modulated by the neural signal amplitudes. To this end, the echo signal from the piezoelectric element is analyzed and the effect of a load resistor is demonstrated. And then, an electronic circuit to implement the modulation function is simulated on the computer and constructed. The experimental results support the main hypothesis of the project

AUTOMATED GUIDED ROBOT (AGR)

This project concerns the design and fabrication of the Automated Guided Robot (AGR) prototype, utilizing artificial intelligence (AI) and genetic algorithm (GA) as a mainframe in helping the robot to generate a self-understanding of the area of work and mobilization to a destination desired by the user. The main objective of this project is to create and develop a Path Planning Mobile Robot able to avoid obstacles in its path and reach a target designated position from its starting point utilizing 3 wheel-based rover body, sensors, linear motors and microcontrollers. Compared to manual mobile robots, AGRs require sensors and control systems that generate feedback for the re-evaluation of an unexpected situation and to detect obstacles in the path the AGR is required to follow. The paper describes the network algorithms developed and used in the design process of the AGR including simulations and circuit designs done for the prototype. A general robotics circuit construction of the mainframe target board for central processing, a controller board for the sensor feedbacks and a small base tri-wheeled structure has been fabricated by the author and continual troubleshooting and enhancement has been done for these components of the AGR. Algorithm conversion to C code programming has been done throughout the project for the obstacle avoidance and path planning algorithms based upon the GA platform ofAI

Design and development of computer controlled active sonar system

Danas je primjena računala najpopularniji, najpouzdaniji i najfleksibilniji projekt za različite vrste upravljačkih i komunikacijskih sustava. Zvučna navigacija i određivanje daljine (SONAR) je moderna ultrazvučna tehnika određivanja daljine primijenjena za prikupljanje informacija o udaljenom objektu bez ikakvog fizičkog kontakta. U ovom se radu predstavlja aktivni SONARNI sustav zasnovan na osobnom računalu (PC). Razvijeni SONARNI sustav u istom modulu sadrži i dijelove odašiljača i dijelove prijemnika. Par piezoelektričnih ultrazvučnih pretvarača od 40 kHz koristi se za prijenos ultrazvuka u pravcu objekta i prijem odbijenog zvuka od predmeta. Za taj je sustav razvijen program nazvan CURF (Computerized Ultrasonic Range Finder) koji koristi Turbo C jezik namijenjen za IBM PC i njegove kopije. Program CURF daje potrebnu podršku za održavanje veze s razvijenim dijelovima uređaja kao i za željene izračune. Nakon obavljenih brojnih ispitivanja ustanovljeno je da razvijeni sustav zadovoljava u odnosu na točnost, jednostavnost, cijenu i potrošnju energije.Nowadays computerization is the most popular, reliable and flexible design for various types of control and communication systems. Sound navigation and ranging (SONAR) is a modern ultrasonic range finding technique used for collecting the information of a distant object without any physical contact. In this paper, a personal computer (PC) based active SONAR system is presented. The developed SONAR system contains both transmitter and receiver parts in the same module. A pair of 40 kHz piezoelectric ultrasonic transducers is used to transmit ultrasound toward the object and receive the reflected from the object respectively. A driver-software named CURF (Computerized Ultrasonic Range Finder) is developed for this system, using Turbo C language aimed at IBM PC and its clone machines. The CURF software provides necessary support for interfacing the developed hardware as well as desired calculations. A number of tests have been done and it is found that the performances of the developed system are good in terms of accuracy, simplicity, cost and power consumption

Safe Kids Car

The main goal of this project is to retrofit toy vehicles, such as Powerwheels cars, with safety systems that can protect the driver and those around the driver. Such systems will include lights, including headlights and taillights, and an automatic braking system, which will activate in the face of an inevitable collision. The system will also work with the driver to prevent collisions, providing warnings of impending danger. Keywords: toy vehicles, collision detection, collision avoidance, automatic braking system, DC motors, automatic headlights