Mechanical & Fluid Systems

Tool for Bending a Metal Tube Precisely in a Confined Space

This tool offers capabilities that prior tools do not. A relatively simple, manually operated tool enables precise bending (typically, within ±1/2° of the specified bend angle) of a metal tube located in a confined space, with a minimum of flattening of the tube and without significant gouging of the tube surface. The tool is designed for use in a situation in which the tube cannot be removed from the confined space for placement in a conventional bench- mounted tube bender. The tool is also designed for use in a situation in which previously available hand-held tube benders do not afford the required precision, do not support the tube wall sufficiently to prevent flattening or gouging, and/or do not fit within the confined space.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Tools and equipment, Product development


Touchdown Ball-Bearing System for Magnetic Bearings

In the event of a touchdown, ball bearings provide full support. The torque-limited touchdown bearing system (TLTBS) is a backup mechanical- bearing system for a high-speed rotary machine in which the rotor shaft is supported by magnetic bearings in steady-state normal operation. The TLTBS provides ballbearing support to augment or supplant the magnetic bearings during startup, shutdown, or failure of the magnetic bearings. The TLTBS also provides support in the presence of conditions (in particular, rotational acceleration) that make it difficult or impossible to control the magnetic bearings or in which the magnetic bearings are not strong enough (e.g., when the side load against the rotor exceeds the available lateral magnetic force).

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Bearings


Flux-Based Deadbeat Control of Induction-Motor Torque

Graphical constructions provide insight into solutions of control problems. An improved method and prior methods of deadbeat direct torque control involve the use of pulse-width modulation (PWM) of applied voltages. The prior methods are based on the use of stator flux and stator current as state variables, leading to mathematical solutions of control equations in forms that do not lend themselves to clear visualization of solution spaces. In contrast, the use of rotor and stator fluxes as the state variables in the present improved method lends itself to graphical representations that aid in understanding possible solutions under various operating conditions. In addition, the present improved method incorporates the superposition of high-frequency carrier signals for use in a motor-self-sensing technique for estimating the rotor shaft angle at any speed (including low or even zero speed) without need for additional shaft-angle-measuring sensors.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Electronic control systems, Electric motors


Piezoelectric Positioning Enables Vibration Assisted Machining

Triangle-shaped actuators create precise ultrafast elliptical diamond tool movement. A precision piezoelectric positioning system with high-bandwidth and high-power enables a new class of precision machining called Vibration Assisted Machining. The actuator and drive electronics optimize stroke, stiffness and dynamic response of the diamond tool.

Posted in: Briefs, Mechanical Components, Mechanics, Electronic control systems, Sensors and actuators, Machining processes, Manufacturing equipment and machinery, Vibration


Accurate Spring Testing

Load-testing machine features can affect the accuracy, precision, repeatability, and reproducibility of test results. Virtually all spring manufacturers must test their products with some kind of load testing machine. Testing ensures that the product is produced and shipped within the customer's specifications. Or does it? Disputes over test results still occur that can cause a multitude of costly problems: returned product, delayed payment, product liability, or customer dissatisfaction. The quality of a spring testing program can largely affect these problems and their associated cost.

Posted in: Briefs, Mechanical Components, Mechanics, Springs, Quality control, Reliability, Performance tests, Test procedures


Compliant Gripper for a Robotic Manipulator

Diverse small objects can be manipulated without force-feedback control. The figure depicts a prototype of a robotic-manipulator gripping device that includes two passive compliant fingers, suitable for picking up and manipulating objects that have irregular shapes and/or that are, themselves, compliant. The main advantage offered by this device over other robotic-manipulator gripping devices is simplicity: Because of the compliance of the fingers, force-feedback control of the fingers is not necessary for gripping objects of a variety of sizes, shapes, textures, and degrees of compliance. Examples of objects that can be manipulated include small stones, articles of clothing, and parts of plants.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Robotics, Parts, Biomechanics


Hybrid Aerial/Rover Vehicle

This robotic vehicle would combine features of balloons and "beach-ball" rovers. A proposed instrumented robotic vehicle called an "aerover" would fly, roll along the ground, and/or float on bodies of liquid, as needed. The aerover would combine features of an aerobot (a robotic lighter-than-air balloon) and a wheeled robot of the "rover" class. An aerover would also look very much like a variant of the "beach-ball" rovers described in "Lightweight 'Beach- Ball' Robotic Vehicles" (NPO-20283), NASA Tech Briefs, Vol. 22, No. 7 (July 1998), page 74. Although the aerover was conceived for use in scientific exploration of Titan (the largest moon of the planet Saturn), the aerover concept could readily be adapted to similar uses on Earth.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, Product development, Robotics, Autonomous vehicles, Marine vehicles and equipment, Spacecraft, Unmanned aerial vehicles


The U.S. Government does not endorse any commercial product, process, or activity identified on this web site.