Motion Control

Ocean Gliders Measure Melting Polar Ice

The rapidly melting ice sheets on the coast of West Antarctica are a potentially major contributor to rising ocean levels worldwide. Although warm water near the coast is thought to be the main factor causing the ice to melt, the process by which this water ends up near the cold continent is not well understood.

Using robotic ocean gliders, Caltech researchers have now found that swirling ocean eddies, similar to atmospheric storms, play an important role in transporting these warm waters to the Antarctic coast—a discovery that will help the scientific community determine how rapidly the ice is melting and, as a result, how quickly ocean levels will rise.

"When you have a melting slab of ice, it can either melt from above because the atmosphere is getting warmer or it can melt from below because the ocean is warm," explains lead author Andrew Thompson, assistant professor of environmental science and engineering. "All of our evidence points to ocean warming as the most important factor affecting these ice shelves, so we wanted to understand the physics of how the heat gets there."

Because the gliders are small—only about six feet long—and are very energy efficient, they can sample the ocean for much longer periods than large ships can. When the glider surfaces every few hours, it "calls" the researchers via a mobile phone–like device located on the tail. The communication allows the researchers to almost immediately access the information the glider has collected.

Like airborne gliders, the bullet-shaped ocean gliders have no propeller; instead they use batteries to power a pump that changes the glider's buoyancy. When the pump pushes fluid into a compartment inside the glider, the glider becomes denser than seawater and less buoyant, thus causing it to sink. If the fluid is pumped instead into a bladder on the outside of the glider, the glider becomes less dense than seawater—and therefore more buoyant—ultimately rising to the surface. Like airborne gliders, wings convert this vertical lift into horizontal motion.


Also: Learn about Remote Sensing of Ice Sheets and Snow.

Posted in: News, Communications, Batteries, Electronics & Computers, Environmental Monitoring, Green Design & Manufacturing, Motion Control, Automation, Robotics, Measuring Instruments, Monitoring, Test & Measurement

Engineers Harvest and Print Parts for New Breed of Aircraft

Student interns and engineers at NASA's Ames Research Center rapidly prototyped and redesigned aircraft using 3D-printed parts. The aircraft was custom-built by repurposing surplus Unmanned Aerial Vehicles (UAVs). By lengthening the wings, the team was able to improve aerodynamic efficiency and help extend the flight time of small, lightweight electric aircraft.

The prototype aircraft are constructed using components from Aerovironment RQ-14 Dragon Eye UAVs that NASA acquired from the United States Marine Corps via the General Services Administration's San Francisco office. Unmodified, these small electric aircraft weigh 5.9 pounds, have a 3.75-foot wingspan and twin electric motors, and can carry a one-pound instrument payload for up to an hour.

After finalizing designs that featured longer and more slender wings and dual fuselages, the teams printed new parts including wing sections, nose cones, winglets, control surfaces, wing ribs and even propellers using the NASA Ames SpaceShop. The 3-D printed wing sections were reinforced using carbon fiber tubing or aluminum rods to give them extra strength without adding significant weight.

Flying as high as 12,500 feet above sea level, multiple small converted Dragon Eye UAVs, including the specialized and highly modified “FrankenEye” platform, will study the chemistry of the eruption plume emissions from Turrialba volcano, near San Jose, Costa Rica.

The goal of the activity is to improve satellite data research products, such as computer models of the concentration and distribution of volcanic gases, and transport-pathway models of volcanic plumes. Some volcanic plumes can reach miles above a summit vent, and drift hundreds to thousands of miles from an eruption site and can pose a severe public heath risk, as well as a potent threat to aircraft.


Also: Learn about Real-Time Minimization of Tracking Error for Aircraft Systems.

Posted in: News, Aerospace, Aviation, Manufacturing & Prototyping, Rapid Prototyping & Tooling, Motion Control, Motors & Drives

2-in-1 Motor Increases Range of Electric Cars

Scientists from Nanyang Technological University (NTU) and German Aerospace Centre (DLR) have invented a 2-in-1 electric motor that increases the range of electric vehicles. The engine integrates the traditional electric motor with the air-conditioning compressor, typically two separate units. This novel, space-saving design allows the use of bigger batteries, which can increase the range of electric vehicles by an additional 15 to 20 percent.

Posted in: News, Energy, Energy Efficiency, Manufacturing & Prototyping, Motion Control, Motors & Drives, Automotive, Transportation

Pulley Mechanism Improves Hand Function After Surgery

Engineers at Oregon State University have developed and successfully demonstrated a simple pulley mechanism to improve hand function after surgery. The device is one of the first instruments ever created that could improve the transmission of mechanical forces and movement while implanted inside the body.

Posted in: News, Mechanical Components, Medical, Rehabilitation & Physical Therapy, Motion Control

Underwater Robot Skims for Port Security

MIT researchers unveiled an oval-shaped submersible robot, a little smaller than a football, with a flattened panel on one side that it can slide along an underwater surface to perform ultrasound scans.

Originally designed to look for cracks in nuclear reactors’ water tanks, the robot could also inspect ships for the false hulls and propeller shafts that smugglers frequently use to hide contraband. Because of its small size and unique propulsion mechanism — which leaves no visible wake — the robots could, in theory, be concealed in clumps of algae or other camouflage. Fleets of them could swarm over ships at port without alerting smugglers and giving them the chance to jettison their cargo.

Sampriti Bhattacharyya, a graduate student in mechanical engineering, built the main structural components of the robot using a 3-D printer. Half of the robot — the half with the flattened panel — is waterproof and houses the electronics. The other half is permeable and houses the propulsion system, which consists of six pumps that expel water through rubber tubes.

Two of those tubes vent on the side of the robot opposite the flattened panel, so they can keep it pressed against whatever surface the robot is inspecting. The other four tubes vent in pairs at opposite ends of the robot’s long axis and control its locomotion.


Also: Learn about Underwater Localization for Transit and Reconnaissance Autonomy.

Posted in: News, Imaging, Manufacturing & Prototyping, Rapid Prototyping & Tooling, Motion Control, Power Transmission, Automation, Robotics

Analyzing 6-Pulse Drive Harmonic Mitigation Techniques for Industrial Automation

Contemporary industrial automation control systems are employing variable frequency drives (VFDs) in ever-increasing numbers. VFDs give control engineers flexibility to precisely regulate the speed and torque of motors in a wide array of applications. The proliferation of these VFDs has brought increased attention to harmonic distortion created by these drives and their effects on the power system. A standard-pulse drive with no built-in harmonic mitigation controls may interfere with neighboring equipment, reduce equipment life, and create a serious negative impact on the quality of utility power. Looking at the theory of operation for the following harmonic mitigation techniques and their typical performance levels may help take the guesswork out of harmonic reduction for these power systems.

Posted in: Articles, Motion Control, Automation

Reliable Locking in High-Vibration Environments

Today’s PCB plug-in connectors must accommodate many trends, including increasing miniaturization, rising levels of performance of electronic components, and growing complexity in machine and system engineering.

Posted in: Articles, Motion Control, Connectors and terminals, Electronic equipment, Connectors and terminals, Electronic equipment, Vibration, Vibration

Robotic Fabric Moves and Contracts

Researchers are developing a robotic, sensor-embedded fabric that moves and contracts. Such an elastic technology could enable a new class of soft robots, stretchable garments, "g-suits" for pilots or astronauts to counteract acceleration effects, and lightweight, versatile robots to roam alien landscapes during space missions.

The robotic fabric is a cotton material containing sensors made of a flexible polymer and threadlike strands of a shape-memory alloy. The strands return to a coiled shape when heated, causing the fabric to move.

"We have integrated both actuation and sensing, whereas most robotic fabrics currently in development feature only sensing or other electronic components that utilize conductive thread," said Rebecca Kramer, an assistant professor of mechanical engineering at Purdue University. "We also use standard sewing techniques to introduce the thread-like actuators and sensors into the fabric, so they could conceivably be integrated into the existing textile manufacturing infrastructure."


Also: See other Sensors tech briefs.

Posted in: News, Aerospace, Materials, Plastics, Motion Control, Automation, Robotics, Sensors

Researchers Equip Robot with Novel Tactile Sensor

Researchers at MIT and Northeastern University have equipped a robot with a novel tactile sensor that lets it grasp a USB cable draped freely over a hook and insert it into a USB port.

The sensor is an adaptation of a technology called GelSight, which was developed by the lab of Edward Adelson, the John and Dorothy Wilson Professor of Vision Science at MIT, and first described in 2009. The new sensor isn’t as sensitive as the original GelSight sensor, which could resolve details on the micrometer scale. But it’s smaller — small enough to fit on a robot’s gripper — and its processing algorithm is faster, so it can give the robot feedback in real time.

A GelSight sensor — both the original and the new, robot-mounted version — consists of a slab of transparent, synthetic rubber coated on one side with a metallic paint. The rubber conforms to any object it’s pressed against, and the metallic paint evens out the light-reflective properties of diverse materials, making it much easier to make precise optical measurements.

In the new device, the gel is mounted in a cubic plastic housing, with just the paint-covered face exposed. The four walls of the cube adjacent to the sensor face are translucent, and each conducts a different color of light — red, green, blue, or white — emitted by light-emitting diodes at the opposite end of the cube. When the gel is deformed, light bounces off of the metallic paint and is captured by a camera mounted on the same cube face as the diodes.

From the different intensities of the different-colored light, the algorithms developed by Adelson’s team can infer the three-dimensional structure of ridges or depressions of the surface against which the sensor is pressed.


Read other Sensors tech briefs.

Posted in: News, LEDs, Lighting, Materials, Motion Control, Optics, Photonics, Automation, Robotics, Sensors

New Algorithm Lets Cheetah Robot Run

Speed and agility are hallmarks of the cheetah: The big predator is the fastest land animal on Earth, able to accelerate to 60 mph in just a few seconds. As it ramps up to top speed, a cheetah pumps its legs in tandem, bounding until it reaches a full gallop.

Now MIT researchers have developed an algorithm for bounding that they’ve successfully implemented in a robotic cheetah — a sleek, four-legged assemblage of gears, batteries, and electric motors that weighs about as much as its feline counterpart.

The team recently took the robot for a test run on MIT’s Killian Court, where it bounded across the grass at a steady clip. In experiments on an indoor track, the robot sprinted up to 10 mph, even continuing to run after clearing a hurdle. The MIT researchers estimate that the current version of the robot may eventually reach speeds of up to 30 mph.

The key to the bounding algorithm is in programming each of the robot’s legs to exert a certain amount of force in the split second during which it hits the ground, in order to maintain a given speed: In general, the faster the desired speed, the more force must be applied to propel the robot forward.

In experiments, the team ran the robot at progressively smaller duty cycles, finding that, following the algorithm’s force prescriptions, the robot was able to run at higher speeds without falling. Sangbae Kim, an associate professor of mechanical engineering at MIT, says the team’s algorithm enables precise control over the forces a robot can exert while running.


Also: Learn about Hall Thrusters for Robotic Solar System Exploration.

Posted in: News, Motion Control, Motors & Drives, Automation, Robotics, Software

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