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Vertical lift stage features sub-micron resolution

Optimal Engineering Systems has released the AT20-30 series of Motorized Vertical Lift Stages featuring sub-micron resolution, very high parallelism, and a vertical lift of 30 mm. The AT20-30-01 is driven by an ultra-precise two-phase stepper motor with a full step resolution of 0.2 microns! This stage also has a knob on the motor for manual adjustment. Features a large 500 mm x 300 mm stage table and high load capacity. Also available as a complete plug-and-play system with a motion controller, drivers, keypad, and joystick.
Learn more and get all the specs.

Tech Tip: Using a step motor as a generator

Engineers at Applied Motion Products run through their lab testing procedures and results when a client requested guidance on connecting a step motor to a small gas engine for use in recharging a 12-V battery. An interesting technical walkthrough on the project and its results.
Read the full Applied Motion Products article.

Rugged high-accuracy hexapod for industrial 6-axis alignment applications

The H-815 6-Axis Hexapod from PI is a low-profile, ruggedized, highly accurate positioning and alignment system designed for continuous 24/7 operation in demanding industrial motion applications such as camera lens alignment (automotive, cell phones etc.), micro-assembly, aerospace test and assembly, micro-LED production, fiber optic alignment, aerospace test and assembly, and more. It provides 6-DOF -- X, Y, Z, pitch, roll, and yaw -- to deliver exceptional flexibility. Load capacity is 22 lb.
Learn more and get all the specs.

Long-life electric actuators: Improved controllability, performance

Thomson Electrak LL Linear Actuators now offer your machine designs a higher speed option, more electronic control options (including CANopen), and a 48-V option to meet the power requirements in battery-powered applications. Thomson says the new Electrak LL choices are for those who want to gain more control over the position, load, and speed of their applications, such as smart railway pantographs and couplers, AGVs, automated farming robots, movable steps, and access lifts for trains and buses.
Learn more and get the specs.

New high-payload vacuum gripper automatically adjusts to box size

The powerful and robust new VGP30 vacuum gripper from OnRobot is capable of handling up to 30 kg (66 lb) and is designed to excel at palletizing boxes and handling irregular shapes and porous surfaces -- even those constructed from cost-saving, thinner cardboard. It automatically adjusts to any box size or interlayer, optimizing air consumption and reducing energy costs. This unit is ready for immediate deployment out of the box and includes all the hardware and software needed for all leading robot brands. Lots more features.
Learn more.

Go inside the revolutionary GAM GPL Robotic Flange Gearbox

GAM's new GPL Series Robotic Planetary Gearbox combines the lowest backlash (<0.1 arcmin) and high tilting rigidity with vibration-free motion for smooth, controlled path motion in robotics and motion control applications. Its patented design guarantees backlash will not increase over the lifetime of the gearbox, so no future adjustments required! Many more benefits.
View the video.

Revamped Step By Step tool to configure Galil motion controllers

Galil introduces its revamped Step By Step tool for Galil Design Kit. Now with enhanced functionality and a new user interface, this tool allows first-time users to configure Galil motion controllers. Along with the existing ability to configure brushed and brushless servos, users are now able to configure steppers, set up serial-type and sine-cosine encoders, and tune axes -- all within the new Step By Step tool.
Learn more and check it out.

Stepper drives detect stalls in open-loop control mode

Automation-Direct has added the new Titanio series of stepper drives from Ever Motion Solutions. These drives offer peak performance, a rich feature set, and work seamlessly with AutomationDirect SureStep^® stepper motors. Three new drives are available with two open-loop (no encoder feedback) models and one open/closed-loop version (a motor-mounted encoder provides position feedback to the drive). Unlike typical stepper drives, Titanio steppers can detect stalls in open-loop control mode by monitoring the motor's back EMF. This allows system designers to take advantage of stall detection without the hassle and expense of a closed-loop system.
Learn more.

New high-thrust linear motor stage

IKO's LT170H2 direct drive linear motor stage delivers 260N of rated force and up to 500N maximum, exceeding the thrust ratings of previous LT stages and expanding the linear stage series' range of suitable applications -- especially those that involve positioning heavy objects in tight spaces. Its redesigned linear motor leverages direct drive technology that is free of mechanical power transmission parts that can otherwise hinder positioning accuracy. It includes C-Lube linear bearings for guidance. Together, they allow the stage to achieve higher thrust forces and high speeds with exceptional precision.
Learn more.

What is a low-waving linear motion guide?

If you are having a problem with your linear guides not always staying perfectly straight during use, it may be due to a phenomenon called waving -- a problem that is particularly critical in high-precision markets such as semiconductor and LCD equipment-related applications or machine tools. Thankfully, THK has an answer.
Read the full article.

Advanced motion controller for BLDC motors

The PCR 56/06 EC SD from Portescap is an integrated hardware and software package for single-axis control of brushless DC motors. It features a user-friendly Windows-based software suite with autotuning capabilities to reduce setup times. With a power supply of up to 56V and a continuous current capability of 5.5A, along with Hall sensor and encoder feedback options, the PCR 56/06 EC SD meets various application requirements with ease. A standout feature is the module-only option, which allows the controller to be mounted directly onto the application's PCB to facilitate a smooth transition from prototyping to series production. Ideal for the Aerospace, Automation, Industrial Power Tools, Medical, and Robotics markets.
Learn more.

3-axis motion made simple using CLICK PLUS PLC

Automation-Direct CLICK PLUS PLCs, when combined with stepper motors, make advanced motion control and edge integration simple for smaller systems. Learn motion control basics, motor options, motion with micro-PLCs and steppers, and more in this informative whitepaper from AutomationDirect. No registration required.
Get the AutomationDirect whitepaper.

Ultra-lightweight humanoid robotics arms are ultra affordable too

RealMan's ultra-lightweight robotic arms offer unmatched agility, strength, and precision at a surprising price. Designed with cutting-edge materials and advanced motion control, these arms enable lifelike movements, making them ideal for manufacturing, service industries, and even domestic assistance. Among these, GEN72 is a consumer-grade robotic arm with a load capacity of 2 kg priced at just over $1,000. It is suitable for large-scale applications such as personal research and development, and commercial service scenarios. Lots of other options.
Discover what RealMan Robotics has to offer.

Advanced 4-axis delta robot for high-speed pick and place

igus has launched its latest high-performance 4-axis delta robot, the DR1000. Designed specifically for fast and precise pick-and-place tasks, this new unit sets a benchmark for cost-effective and efficient automation solutions. The DR1000 boasts an impressive working diameter of 1,000 mm and an additional rotary axis that provides four degrees of freedom, enabling users to grip and orient components seamlessly. An ideal choice for end-of-line applications. Fast at 96 picks/min.
Learn more.

How to maximize and optimize stepper motor control

Engineers from Performance Motion Devices take a comprehensive look at how to control two-phase stepper motors, beginning with the basics (operations, strengths, and weaknesses) and moving on to traditional and updated advanced techniques for control including closed loop. A very thorough presentation.
Read this Performance Motion Devices article.

What's a unified momentum model? New theory could improve the design and operation of wind farms

Engineers at MIT have developed a comprehensive model that accurately represents the airflow around rotors even under extreme conditions, such as when the blades are operating at high forces and speeds, or are angled in certain directions. [Credit: Image courtesy of the researchers]

 

 

 

 

The first comprehensive model of rotor aerodynamics could improve the way turbine blades and wind farms are designed and how wind turbines are controlled.

By David L. Chandler, MIT

The blades of propellers and wind turbines are designed based on aerodynamics principles that were first described mathematically more than a century ago. However, engineers have long realized that these formulas don't work in every situation. To compensate, they have added ad-hoc "correction factors" based on empirical observations.

Now, for the first time, engineers at MIT have developed a comprehensive, physics-based model that accurately represents the airflow around rotors even under extreme conditions, such as when the blades are operating at high forces and speeds, or are angled in certain directions. The model could improve the way rotors themselves are designed, but also the way wind farms are laid out and operated. The new findings are described in the journal Nature Communications, in an open-access paper by MIT postdoc Jaime Liew, doctoral student Kirby Heck, and Michael Howland, the Esther and Harold E. Edgerton Assistant Professor of Civil and Environmental Engineering.

"We've developed a new theory for the aerodynamics of rotors," Howland says. This theory can be used to determine the forces, flow velocities, and power of a rotor, whether that rotor is extracting energy from the airflow, as in a wind turbine, or applying energy to the flow, as in a ship or airplane propeller. "The theory works in both directions," he says.

Because the new understanding is a fundamental mathematical model, some of its implications could potentially be applied right away. For example, operators of wind farms must constantly adjust a variety of parameters, including the orientation of each turbine as well as its rotation speed and the angle of its blades, in order to maximize power output while maintaining safety margins. The new model can provide a simple, speedy way of optimizing those factors in real time.

"This is what we're so excited about, is that it has immediate and direct potential for impact across the value chain of wind power," Howland says.

Modeling the momentum
Known as momentum theory, the previous model of how rotors interact with their fluid environment -- air, water, or otherwise -- was initially developed late in the 19th century. With this theory, engineers can start with a given rotor design and configuration, and determine the maximum amount of power that can be derived from that rotor -- or, conversely, if it's a propeller, how much power is needed to generate a given amount of propulsive force.

Momentum theory equations "are the first thing you would read about in a wind energy textbook, and are the first thing that I talk about in my classes when I teach about wind power," Howland says. From that theory, physicist Albert Betz calculated in 1920 the maximum amount of energy that could theoretically be extracted from wind. Known as the Betz limit, this amount is 59.3% of the kinetic energy of the incoming wind.

Just a few years later, however, others found that the momentum theory broke down "in a pretty dramatic way" at higher forces that correspond to faster blade rotation speeds or different blade angles, Howland says. It fails to predict not only the amount, but even the direction of changes in thrust force at higher rotation speeds or different blade angles: Whereas the theory said the force should start going down above a certain rotation speed or blade angle, experiments show the opposite -- that the force continues to increase. "So, it's not just quantitatively wrong, it's qualitatively wrong," Howland says.

The theory also breaks down when there is any misalignment between the rotor and the airflow, which Howland says is "ubiquitous" on wind farms, where turbines are constantly adjusting to changes in wind directions. In fact, in an earlier paper in 2022, Howland and his team found that deliberately misaligning some turbines slightly relative to the incoming airflow within a wind farm significantly improves the overall power output of the wind farm by reducing wake disturbances to the downstream turbines.

In the past, when designing the profile of rotor blades, the layout of wind turbines in a farm, or the day-to-day operation of wind turbines, engineers have relied on ad-hoc adjustments added to the original mathematical formulas, based on some wind tunnel tests and experience with operating wind farms, but with no theoretical underpinnings.

Instead, to arrive at the new model, the team analyzed the interaction of airflow and turbines using detailed computational modeling of the aerodynamics. They found that, for example, the original model had assumed that a drop in air pressure immediately behind the rotor would rapidly return to normal ambient pressure just a short way downstream. However, it turns out, Howland says, that as the thrust force keeps increasing, "that assumption is increasingly inaccurate."

And the inaccuracy occurs very close to the point of the Betz limit that theoretically predicts the maximum performance of a turbine -- and therefore is just the desired operating regime for the turbines. "So, we have Betz's prediction of where we should operate turbines, and within 10 percent of that operational set point that we think maximizes power, the theory completely deteriorates and doesn't work," Howland says.

Through their modeling, the researchers also found a way to compensate for the original formula's reliance on a one-dimensional modeling that assumed the rotor was always precisely aligned with the airflow. To do so, they used fundamental equations that were developed to predict the lift of three-dimensional wings for aerospace applications.

The researchers derived their new model, which they call a unified momentum model, based on theoretical analysis, and then validated it using computational fluid dynamics modeling. In follow-up work not yet published, they are doing further validation using wind tunnel and field tests.

Fundamental understanding
One interesting outcome of the new formula is that it changes the calculation of the Betz limit, showing that it's possible to extract a bit more power than the original formula predicted. Although it's not a significant change -- on the order of a few percent -- "it's interesting that now we have a new theory, and the Betz limit that's been the rule of thumb for a hundred years is actually modified because of the new theory," Howland says, "and that's immediately useful." The new model shows how to maximize power from turbines that are misaligned with the airflow, which the Betz limit cannot account for.

The aspects related to controlling both individual turbines and arrays of turbines can be implemented without requiring any modifications to existing hardware in place within wind farms. In fact, this has already happened, based on earlier work from Howland and his collaborators two years ago that dealt with the wake interactions between turbines in a wind farm, and was based on the existing, empirically based formulas.

"This breakthrough is a natural extension of our previous work on optimizing utility-scale wind farms," he says, because in doing that analysis, they saw the shortcomings of the existing methods for analyzing the forces at work and predicting power produced by wind turbines. "Existing modeling using empiricism just wasn't getting the job done," he says.

In a wind farm, individual turbines will sap some of the energy available to neighboring turbines because of wake effects. Accurate wake modeling is important both for designing the layout of turbines in a wind farm, and also for the operation of that farm, determining moment to moment how to set the angles and speeds of each turbine in the array.

Until now, Howland says, even the operators of wind farms, the manufacturers, and the designers of the turbine blades had no way to predict how much the power output of a turbine would be affected by a given change such as its angle to the wind without using empirical corrections. "That's because there was no theory for it. So, that's what we worked on here. Our theory can directly tell you, without any empirical corrections, for the first time, how you should actually operate a wind turbine to maximize its power," he says.

Because the fluid flow regimes are similar, the model also applies to propellers, whether for aircraft or ships, and also for hydrokinetic turbines such as tidal or river turbines. Although they didn't focus on that aspect in this research, "it's in the theoretical modeling naturally," he says.

The new theory exists in the form of a set of mathematical formulas that a user could incorporate in their own software, or as an open-source software package that can be freely downloaded from GitHub. "It's an engineering model developed for fast-running tools for rapid prototyping and control and optimization," Howland says. "The goal of our modeling is to position the field of wind energy research to move more aggressively in the development of the wind capacity and reliability necessary to respond to climate change."

Published September 2024

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