March 12, 2019 Volume 15 Issue 10

Motion Control News & Products

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New Sinamics G120X drive series specializes in infrastructure pump, fan, and compressor applications

Siemens has introduced the new Sinamics G120X drive, a simple, seamless, and easy-to-use drive designed for use in pump, fan, and compressor applications in industries such as water/wastewater, HVAC/R, irrigation/agriculture, and in industrial environments. Sinamics G120X has a power range of 1 to 700 hp (0.75 to 630 kW) and can operate in temps from -4 to 140 F (-20 to 60 C) with any standard motor, including synchronous reluctance motors (SRM). It has an integral DC choke that improves harmonics and EMC performance. Sinamics G120X meets all the latest and upcoming UL, NEMA, and EN/IEC standards for 2019 and beyond and offers up to 100-kA short-circuit current rating (SCCR), ensuring enhanced product safety and energy efficiency.
Learn more.

High-speed, high-precision mechanical gantry system

PI has added to its family of precision automation sub-systems with the A-351 MGS, a compact mechanical gantry system engineered to deliver maximum throughput for applications that require controlled precise overhead motion. The gantry is driven by linear motors, and each axis is equipped with preloaded linear bearings. Applications include high-precision 3D printers, assembly, pick-and-place, alignment, inspection, and other industrial automation applications. The A-351 MGS gantry system is designed for high load capacity of 20 kg, twice the amount of its A-341 air-bearing-based sibling. Absolute-measuring linear encoders with nanometer resolution are optional.
Learn more.
See PI automation platforms in action.

New inductive-technology position sensors

Novotechnik's TF1 Series touchless linear position sensors overcome issues with legacy magnetostrictive technology. They are unaffected by strong magnetic fields and metal flakes or filings present in a user's environment. The TF1 Series consists of an inductively coupled position marker attached to a moving rod/piece of the user's application that requires a position measurement and the sensor with operational and programming status LEDs. While operating, LEDs indicate whether the sensor is operating and the marker within measuring range or out of range, as well as indicating results of internal diagnostics for valid output from the sensor. Can also measure speed and temperature.
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High-traction robot goes underground

Recent developments in motion control and engineering make it possible to inspect and perform maintenance in compact sewers from the inside. The underground sewer robot is equipped with a swiveling camera and an air-powered milling machine driven by FAULHABER miniature DC motors from MICROMO.
Read the full article.

How to convert from hydraulic to electric high-force linear actuators

Machine designers are converting existing linear motion systems from hydraulic to electric due to the technology's many benefits, but the process involves considering the actual force output of the cylinder, the duty cycle, and the motion profile. Specialists at Tolomatic tackle these points. Includes a very informative video.
Read the Tolomatic blog.

Gain more torque with a cooler-running motor

The slim-design G3718V whisper torque motor from Lin Engineering incorporates a heat-sink design within the stator laminations to allow for passive cooling. When your motor operates cooler, you can increase power to gain more torque without overheating, or you can save energy and still perform at optimal performance. At only 22.8 mm long, this motor produces 25 oz-in. of torque.
Click here to learn more.

Quiet 3-to-1 speed reducers use traction drive technology for 98% efficiency

Rolling Motion Industries (RMI) has released two new traction drive speed reducers. With only six moving parts, they typically outlast conventional gearboxes and speed reducers by a factor of three. The MAR17-1-3.1 Speed Reducer is designed for input speeds up to 3,600 rpm with 10 to 20 in.-lb of torque, and the MAR-23-1-3.1 Speed Reducer is rated for the same speeds but with an input of 20 to 30 in.-lb of torque. As the output speed is reduced by a factor of three, the output torque increases by a factor of three. These high-efficiency speed reducers generate up to 72 percent less heat because they use a special engineered fluid that cools and lubricates the traction drive.
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Smart Sensor checks condition of bearings

ABB has launched the ABB Ability Smart Sensor for Dodge mounted bearings, part of the ABB Ability Digital Powertrain, that enables "health checks" for bearings. The smart sensor technology provides an early indicator of any potential problems by assessing the condition of bearings from vibration and temperature information. Eighty percent of bearing failures are lubrication related, and a bearing "running hot" can indicate that proper lubrication procedures are not in place. Monitoring a bearing's vibration can also indicate potential system problems. Prevent downtime on applications such as bulk material-handling conveyors as well as applications in the food-and-beverage and air-handling sectors.
Learn more.

New industrial-grade optical encoder from Quantum Devices

The Model QDH20 encoder provides an improved feedback solution in applications typically using a standard size 20 package. It features superb mechanical and environmental protection. Outputs consist of a quadrature A & B with reference pulse Z as a standard feature. The output can be configured with either the industrial standard 5- to 26-V OL7272 line driver or open collector outputs. Two heavy-duty bearing sets hold the output shaft, and two more bearings (along with an integral flexible spring mount) isolate the working pieces of the encoder from mechanical stresses. Features include 500-kHz fundamental frequency response, high operating temp option (100 C), and resolutions up to 5,000 lines per revolution direct read. Available through Servo2Go.
Learn more.

Single-cylinder engines for combustion research

Southwest Research Institute (SwRI) has designed and manufactured two advanced single-cylinder engines for combustion research and friction analysis, as well as alternative fuel, wear, optical, crank offset, and bore-to-stroke relationship studies. The engines, one for light- and medium-duty applications and one for heavy-duty applications, can accommodate either multi-cylinder or single-cylinder heads through a custom cylinder barrel and head support shelf. They include several unique patent-pending innovations, including mechanisms that adjust compression ratios and crankshaft offsets without the need for disassembling the engine. Optical access, dynamic cam phasing, secondary balancers, and floating liner devices can be added to the standard configurations. Specs available in online "Single-Cylinder Research Engine" flyer.
Click here to learn more.

Hybrid gantry stage provides precision XY/XYZ motion with linear motors, air bearings, and ball bearings

PI's new A-341 hybrid gantry XY/XYZ positioning stage provides the framework for controlled precise overhead motion that is often sought after for 3D printing, assembly, pick-and-place, alignment, inspection, and industrial automation applications. The A-341 HGS hybrid gantry is designed to combine maximum throughput with smooth and highly accurate motion in a compact envelope. It features a unique hybrid bearing design. The cross axis utilizes a frictionless air bearing guiding system, which allows for excellent velocity control, repeatability, straightness, and cleanliness. The lower dual-motor axis uses precision mechanical linear bearings for rigidity and reduced size. This combo offers an overhead gantry motion platform optimized for step and scan applications in the smallest possible form factor.
Learn more.

Micro-brakes for precise motion control applications

The ultra-compact 112 Model Electromag-netic Micro-Brakes from Miki Pulley ensure fast response in high-torque, demanding applications. The simple design features a stator with integrated mounting flange, proprietary composite friction liner, and armature complete with ring plate spring and hub. These brakes halt rotation mechanically by utilizing an electromagnetic field to create mechanical friction. With fast response, the brake's armature engages the stator when the coil is energized. A constant-force plate spring transfers torque to the rotating brake body, halting all motion.
Learn more.

Electric high-force linear actuator choices: Ball vs. roller screw

Many applications require high-force linear actuators -- from moving equipment in a foundry to powering a press in metal forming to guiding heavy logs in a sawmill. Whatever the application, a machine designer is faced with a choice: whether to specify a ball or roller screw in the electric high-force linear actuator. Learn how to make the best decision for your application.
Read the Tolomatic blog.

Using SmartMotor data to diagnose linear actuator performance problems

Effective troubleshooting of a motion control system problem can be a daunting and time-consuming process, even for seasoned automation professionals. However, the Moog Animatics SmartMotor fully integrated servo, with built-in controller and firmware, is constantly monitoring a variety of operating parameters. This case study investigates how that data can be used to quickly and effectively troubleshoot and resolve a motion control system problem.
Read the Moog Animatics article.

Advantages of electroformed metal bellows

Servometer metal bellows manufactured using our patented electro-deposition process create flexibility, protection, motion, and balance for systems requiring precise, repeatable results. This exclusive manufacturing technology produces electroformed bellows that offer unique characteristics such as high-strength but lightweight construction and custom engineered geometries. Learn more by viewing our "Electroforming Basics of Miniature and Specialized Components" white paper.
Read the white paper (no registration required).

Computer vision challenger: RFID tags provide new way for robots to track moving objects with unprecedented precision

By Rob Matheson, MIT

A novel system developed at MIT uses RFID tags to help robots home in on moving objects with unprecedented speed and accuracy. The system could enable greater collaboration and precision by robots working on packaging and assembly, and by swarms of drones carrying out search-and-rescue missions.

In a paper presented at the USENIX Symposium on Networked Systems Design and Implementation in February 2019, the researchers show that robots using the system can locate tagged objects within 7.5 msec, on average, and with an error of less than a centimeter.

In the system, called TurboTrack, an RFID (radio-frequency identification) tag can be applied to any object. A reader sends a wireless signal that reflects off the RFID tag and other nearby objects, and rebounds to the reader. An algorithm sifts through all the reflected signals to find the RFID tag's response. Final computations then leverage the RFID tag's movement -- even though this usually decreases precision -- to improve its localization accuracy.

MIT Media Lab researchers are using RFID tags to help robots home in on moving objects with unprecedented speed and accuracy, potentially enabling greater collaboration in robotic packaging and assembly and among swarms of drones. [Photo courtesy of the researchers]





The researchers say the system could replace computer vision for some robotic tasks. As with its human counterpart, computer vision is limited by what it can see, and it can fail to notice objects in cluttered environments. Radio frequency signals have no such restrictions: They can identify targets without visualization, within clutter, and through walls.

To validate the system, the researchers attached one RFID tag to a cap and another to a bottle. A robotic arm located the cap and placed it onto the bottle, held by another robotic arm. In another demonstration, the researchers tracked RFID-equipped nanodrones during docking, maneuvering, and flying. In both tasks, the system was as accurate and fast as traditional computer-vision systems, while working in scenarios where computer vision fails, the researchers report.

"If you use RF signals for tasks typically done using computer vision, not only do you enable robots to do human things, but you can also enable them to do superhuman things," says Fadel Adib, an assistant professor and principal investigator in the MIT Media Lab, and founding director of the Signal Kinetics Research Group. "And you can do it in a scalable way, because these RFID tags are only 3 cents each."

In manufacturing, the system could enable robot arms to be more precise and versatile in, say, picking up, assembling, and packaging items along an assembly line. Another promising application is using handheld "nanodrones" for search-and-rescue missions. Nanodrones currently use computer vision and methods to stitch together captured images for localization purposes. These drones often get confused in chaotic areas, lose each other behind walls, and can't uniquely identify each other. This all limits their ability to, say, spread out over an area and collaborate to search for a missing person. Using the researchers' system, nanodrones in swarms could better locate each other, for greater control and collaboration.

"You could enable a swarm of nanodrones to form in certain ways, fly into cluttered environments and even environments hidden from sight, with great precision," says first author Zhihong Luo, a graduate student in the Signal Kinetics Research Group.

The other Media Lab co-authors on the paper are visiting student Qiping Zhang, postdoc Yunfei Ma, and Research Assistant Manish Singh.

Super resolution
Adib's group has been working for years on using radio signals for tracking and identification purposes, such as detecting contamination in bottled foods, communicating with devices inside the body, and managing warehouse inventory.

Similar systems have attempted to use RFID tags for localization tasks. But these come with tradeoffs in either accuracy or speed. To be accurate, it may take them several seconds to find a moving object; to increase speed, they lose accuracy.

The challenge was achieving both speed and accuracy simultaneously. To do so, the researchers drew inspiration from an imaging technique called "super-resolution imaging." These systems stitch together images from multiple angles to achieve a finer-resolution image.

"The idea was to apply these super-resolution systems to radio signals," Adib says. "As something moves, you get more perspectives in tracking it, so you can exploit the movement for accuracy."

The system combines a standard RFID reader with a "helper" component that's used to localize radio frequency signals. The helper shoots out a wideband signal comprising multiple frequencies, building on a modulation scheme used in wireless communication, called orthogonal frequency-division multiplexing.

The system captures all the signals rebounding off objects in the environment, including the RFID tag. One of those signals carries a signal that's specific to the specific RFID tag, because RFID signals reflect and absorb an incoming signal in a certain pattern, corresponding to bits of 0s and 1s, that the system can recognize.

Because these signals travel at the speed of light, the system can compute a "time of flight" -- measuring distance by calculating the time it takes a signal to travel between a transmitter and receiver -- to gauge the location of the tag, as well as the other objects in the environment. But this provides only a ballpark localization figure, not subcentimeter precision.

Leveraging movement
To zoom in on the tag's location, the researchers developed what they call a "space-time super-resolution" algorithm.

The algorithm combines the location estimations for all rebounding signals, including the RFID signal, which it determined using time of flight. Using some probability calculations, it narrows down that group to a handful of potential locations for the RFID tag.

As the tag moves, its signal angle slightly alters -- a change that also corresponds to a certain location. The algorithm then can use that angle change to track the tag's distance as it moves. By constantly comparing that changing distance measurement to all other distance measurements from other signals, it can find the tag in a three-dimensional space. This all happens in a fraction of a second.

"The high-level idea is that, by combining these measurements over time and over space, you get a better reconstruction of the tag's position," Adib says.

"The work reports sub-centimeter accuracy, which is very impressive for RFID," says Lili Qiu, a professor of computer science at the University of Texas at Austin whose research focuses on wireless networking and communications. "The paper proposes an interesting idea that lets a 'helper' transmit a wideband signal compatible with RFID protocol to achieve high tracking accuracy [and] develops a ... framework for RF localization that fuses measurements across time and across multiple antennas. The system has potential to support [the researchers'] target applications, such as robotic assembly and nanodrones. ... It would be very interesting to see the field test results in the future."

The work was sponsored, in part, by the National Science Foundation.

Published March 2019

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