Motion Control

Robust Gimbal System for Small-Payload Manipulation

This is a low-mass, small-volume gimbal unit. NASA’s Jet Propulsion Laboratory, Pasadena, California Spaceborne gimbal systems are typically bulky with large footprints. Such a gimbal system may consist of a forked elevation stage rotating on top of the azimuth motor, and occupy a large volume. Mounting flexibility of such a system may be limited.

Posted in: Articles, Briefs, TSP, Motors & Drives

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A Phase-Changing Pendulum to Control Spherical Robots and Buoy Sensors

The pendulum adds new flexibility to motion control. NASA’s Jet Propulsion Laboratory, Pasadena, California A novel mechanical control system has been proposed for spherical robots to be used as multifunctioning sensor buoys in areas with ambient forces such as winds or currents. The phase-changing pendulum has been specifically designed for Moballs, a self-powered and controllable multifunctioning spherical sensor buoy to be used in the Arctic and Antarctica, or in other solar system planets or moons with atmosphere, such as Mars or Titan. The phase-changing pendulum has been designed to function in different phases: 1) When used as the spherical buoy, the Moball needs to take advantage of external forces such as the wind for its mobility. With no constraints, it could keep the center of mass in the geometric center of the sphere to facilitate the sphere’s movement. 2) However, as soon as the Moball needs to slow down or stop, the sphere’s center of mass can be lowered. 3) Furthermore, the phase-changing pendulum could lean to the sides, thereby changing the direction of the Moball by biasing its center of mass to the corresponding side. The Moballs could take advantage of such a novel phase-changing pendulum to go as fast as possible using the ambient winds, and to stop or steer away when facing hazardous objects or areas (such as the gullies), or when they need to stop in an area of interest in order to perform extensive tests. It is believed that this is the very first time that a pendulum has been suggested to control a spherical structure where both the length and the angle of the pendulum are adjustable in order to control the sphere. 4) Finally, the phase-changing pendulum could also control the sphere in the absence of wind. The spherical sensor buoys or Moballs could use the stored harvested energy (e.g., from sunlight or earlier wind-driven motions) to move the phase-changing pendulum and create torque, and make the spherical sensor buoys initiate rolling with the desired speed and direction. This is especially useful when the spheres need to get close to an object of interest in order to examine it.

Posted in: Articles, Briefs

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Computation of Wing Deflection and Slope from Measured Strain

Patent-pending methodology computes detailed wing loads during actual flight. Armstrong Flight Research Center, Edwards, California A lightweight, robust fiber-optic system is the technology behind a new method to compute wing deflection and slope from measured strain of an aircraft. This state-of-the-art sensor system is small, easy to install, and fast, and offers the first-ever means of obtaining real-time strain measurements that can accurately determine wing deflection and slope during flight. Such measurements are particularly useful for real-time virtual displays of wing motion, aircraft structural integrity monitoring, active drag reduction, active flexible motion control, and active loads alleviation.

Posted in: Articles, Briefs, Aviation, Measuring Instruments

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Naval Shipyard Automates Dry Dock Operation

Pearl Harbor Naval Station and Hickam Air Force Base have grown up together around the historic port known as Wai’Momi, adjacent to Honolulu. Pearl Harbor Naval Shipyard (PHNSY), located at Joint Base Pearl Harbor-Hickam, is a one-stop regional maintenance center for the Navy’s surface ships and submarines. It is the only intermediate maintenance facility for submarines in the Middle Pacific.

Posted in: Application Briefs

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Wing-Flapping Aircraft Hovers and Flies

Life-sized, hummingbird-like, unmanned surveillance aircraft weighs two-thirds of an ounce, including batteries and video camera. The Nano Hummingbird is a miniature aircraft developed under the Nano Air Vehicle (NAV) program funded through the Defense Advanced Research Projects Agency (DARPA). DARPA was established to prevent strategic surprise from negatively impacting U.S. national security, and to create strategic surprise for U.S. adversaries by maintaining the technological superiority of the U.S. military. The agency relies on diverse performers to apply multidisciplinary approaches to advance knowledge through basic research, and create innovative technologies that address current practical problems through applied research.

Posted in: Application Briefs

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Motion Control System Gives Farmers a Hands-Free Approach in Vehicles

The important job of a farmer requires long hours of field work. The often monotonous tasks of driving agricultural vehicles to work long rows in the field — whether it be planting, maintenance, or harvesting — is undeniably arduous and fraught with potential for human error. With advances in the development of mechanical steering devices, farmers can now program steering patterns to allow their vehicles to operate hands-free and more accurately than ever before.

Posted in: Application Briefs

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Compact Active Vibration Control System

A highly directional actuator can be shaped so that it couples to the response of a flexible structure in the same manner as point sensors. Langley Research Center, Hampton, Virginia This innovation consists of an analog controller, diamond-shaped patch actuator, and point sensors (such as accelerometers). The actuator is designed to couple to the flexural response of the structure in the same manner as a group of point sensors. This results in a co-located transducer pair. The signals from all sensors are combined, filtered, and amplified within the analog controller. The resulting signal is then applied to the actuator, which generates a control force out-of-phase with the measured response. Because the transducers are co-located, the vibration control system is inherently robust to variations in properties of the underlying structure that is being controlled. This type of control system actively suppresses the vibration of a flexible structure using surface-mounted transducers without any external mechanical connections.

Posted in: Briefs, TSP

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