NASA Tech Briefs Index, 1977, volume 2, numbers 1-4

Announcements of new technology derived from the research and development activities of NASA are presented. Abstracts, and indexes for subject, personal author, originating center, and Tech Brief number are presented for 1977

A novel ball joint wear sensor for low-cost structural health monitoring of off-highway vehicles

Mechatronic agricultural machines and equipment are continuously increasing their complexity and cost. In order to ensure their efficiency and reliability and preserve their value, it is important to actively monitor damaging and wear occurring on critical components. This approach needs the introduction of sensors on the machine, which allow continuous monitoring of the residual life of components. This work presents the development and testing of a wear sensor for a ball joint which can be applied for monitoring and diagnostic in off-highway vehicles, automotive and the industrial fields. Many peculiar features make this sensor innovative and contribute to the advance of the technology in the sector: there are no other active sensors for this specific and safety-critical joint; it has an ultra-low power consumption and can be self-powered through energy harvesting; it implements wireless connectivity; it is simple, small size and low cost. This wear sensor for the ball joint is firstly aimed at monitoring the damage of the ball joint placed between the steering actuator and the wheel spindle, since failure of the joint leads to complete loss of steering action. However, the sensor can be applied to any application involving a safety-critical ball joint (e.g. the front suspension of a vehicle). The present work describes the conceptual design and development of the whole mechatronic sensor, which includes the mechanical joint sensor and the electronic board which manages the system. Validation of the ball joint wear sensor, which was performed on an agricultural tractor through tests on a track, proved the reliability of the proposed solution

An autonomous self-reconfigurable modular robotic system with optimised docking connectors

Includes bibliographical references.Self-Reconfigurable Modular Robots are robotic systems consisting of a number of self-contained modules that can autonomously interconnect in different positions and orientations thereby varying the shape and size of the overall modular robot. This ground breaking capability is what in theory, makes self-reconfigurable modular robots more suitable for use in the navigation of unknown or unstructured environments. Here, they are required to reconfigure into different forms so as to optimise their navigation capabilities, a feat that is rendered impossible in conventional specialised robots that lack reconfiguration capabilities. However, the frequent development and use of self-reconfigurable modular robots in everyday robotic navigation applications is significantly hampered by the increased difficulty and overall cost of production of constituent robotic modules. One major contributor to this is the difficulty of designing suitably robust and reliable docking mechanisms between individual robotic modules. Such mechanisms are required to be mechanically stable involving a robust coupling mechanism, and to facilitate reliable inter-module power sharing and communication. This dissertation therefore proposes that the design and development of a functional low cost self-reconfigurable modular robot is indeed achievable by optimising and simplifying the design of a robust and reliable autonomous docking mechanism. In this study, we design and develop such a modular robot, whose constituent robotic modules are fitted with specialised docking connectors that utilise an optimised docking mechanism. This modular robot, its robotic modules and their connectors are then thoroughly tested for accuracy in mobility, electrical and structural stability, inter-module communication and power transfer, self-assembly, self-reconfiguration and self-healing, among others. The outcome of these testing procedures proved that it is indeed possible to optimise the docking mechanisms of self-reconfigurable modular robots, thereby enabling the modular robot to more easily exhibit efficient self-reconfiguration, self-assembly and self-healing behaviours. This study however showed that the type, shape, functionality and structure of electrical contacts used within the docking connectors for inter-module signal transfer and communication play a major role in enabling efficient self-assembly, self-reconfiguration and self-healing behaviours. Smooth spring loaded metallic electrical contacts incorporated into the docking connector design are recommended. This study also highlights the importance of closed loop control in the locomotion of constituent robotic modules, especially prior to docking. The open loop controlled locomotion optimisations used in this project were not as accurate as was initially expected, making self-assembly rather inaccurate and inconsistent. It is hoped that the outcomes of this research will serve to improve the docking mechanisms of self-reconfigurable modular robots thereby improving their functionality and pave the way for future large scale use of these robots in real world applications

Autonomous electrical current monitoring system for aircraft

Aircraft monitoring systems offer enhanced safety, reliability, reduced maintenance cost and improved overall flight efficiency. Advancements in wireless sensor networks (WSN) are enabling unprecedented data acquisition functionalities, but their applicability is restricted by power limitations, as batteries require replacement or recharging and wired power adds weight and detracts from the benefits of wireless technology. In this paper, an energy autonomous WSN is presented for monitoring the structural current in aircraft structures. A hybrid inductive/hall sensing concept is introduced demonstrating 0.5 A resolution, < 2% accuracy and frequency independence, for a 5 A – 100 A RMS, DC-800 Hz current and frequency range, with 35 mW active power consumption. An inductive energy harvesting power supply with magnetic flux funnelling, reactance compensation and supercapacitor storage is demonstrated to provide 0.16 mW of continuous power from the 65 μT RMS field of a 20 A RMS, 360 Hz structural current. A low-power sensor node platform with a custom multi-mode duty cycling network protocol is developed, offering cold starting network association and data acquisition/transmission functionality at 50 μW and 70 μW average power respectively. WSN level operation for 1 minute for every 8 minutes of energy harvesting is demonstrated. The proposed system offers a unique energy autonomous WSN platform for aircraft monitoring

Vibration-powered sensing system for engine condition monitoring

Condition monitoring is becoming an established technique for managing the maintenance of machinery in transport applications. Vibration energy harvesting allows wireless systems to be powered without batteries, but most traditional generators have been designed to operate at fixed frequencies. The variety of engine speeds (and hence vibration frequencies) in transport applications therefore means that these are not usable. This paper describes the application-driven specification, design and implementation of a novel vibration-powered sensing system for condition monitoring of engines. This demonstrates that, through careful holistic design of the entire system, condition monitoring systems can be powered solely from machine vibration, managing their energy resources and transmitting sensed data wirelessly

Index to NASA Tech Briefs, January - June 1966

Index to NASA technological innovations for January-June 196

Stabilization, pointing and command control of a balloon-borne 1-meter telescope

A 1-meter balloon-borne telescope has been constructed and flown to observe far-infrared radiation from celestial sources. The attitude control systems must perform to the diffraction limit of the telescope for stabilization and have positioning capability for source acquisition. These and associated systems are discussed in detail, as is the command control of the payload as a whole