What are monolithic XY tables?

XY tables are constructed from two linear axes – typically driven by linear motors, ball screws, or lead screws – that are mounted perpendicular to each other in either a stacked or a monolithic design. Stacked XY tables consist of two complete, separate axes mounted together, much the same way they are configured in a […]

Linear motion for robotic handling in automated warehouses

When designing and configuring an automated warehouse, one design goal is to keep the system as light and compact as possible. Depending on the size of the load being moved, there are two common types of automated warehouses. In lighter applications, aluminum structures can handle loads up to 100 kilograms, while steel structures are good […]

7 linear motion principles that electrical engineers should know

Electrical and controls engineers are normally tasked with selecting and integrating the electronic components that go into a motion control system, such as motors, drives, controls, feedback devices, and HMIs. In doing so, their primary concerns tend to be on making the various components communicate with each other, working through complex equations for drive tuning, […]

Motion and control objectives for automated storage and retrieval systems

Automated storage and retrieval systems are a key enabler of the next-day delivery we’ve come to expect from online retailers. But like other types of automation, AS/RS equipment must meet the customer’s objectives for safety, footprint, and energy efficiency. It used to be that as you drove through industrial suburbs, just beyond cities such as […]

XY tables: How do they differ from Cartesian and gantry systems?

There are many ways to build linear systems for motion in the X, Y, and/or Z directions – also known as Cartesian coordinates. The terms we generally use to refer to these systems depend on how the axes are assembled, where the load is positioned, and to some extent, what type of use the system […]

Four laws of electromagnetism that you should know

The operation of electric motors is governed by various laws of electricity and magnetism, including Faraday’s law of induction, Ampère’s circuital law, Lenz’ law, and the Lorentz force. The first two – Faraday’s law and Ampère’s circuital law – are included in Maxwell’s equations. Together with Lenz’ law and the Lorentz force, these principles form […]

What is a chopper drive for a stepper motor?

There are two primary types of drivers for stepper motors, constant voltage drives (also referred to as L/R drives), and constant current drives (also referred to as chopper drives). One difficulty with stepper motor operation is that the time constant (L/R) of the motor windings prevents current from increasing rapidly during pulses. This means that […]

What makes miniature ball screws unique?

Ball screws are used in a wide variety of applications, but some of the most challenging are those on the extreme ends of the performance spectrum – from large diameter, large lead screws for machine tools, to screws with small diameters and very fine leads for optical and medical applications. For very small, high-precision movements, […]

Encoder resolution and accuracy: What’s the difference?

Encoders are at the heart of any closed loop servo system, providing feedback to the controller, which uses this information to determine if the motor reached the commanded position or velocity. Thus, encoder resolution and accuracy are essential to the proper operation of a closed-loop system. Resolution is the distance over which a single encoder […]

How are encoders used for speed measurement?

The most common use for encoders is to measure angular or linear distance, but encoders can also be used to perform speed or velocity measurements. This is possible because there is a linear relationship between an encoder’s pulse frequency and its rotational velocity. In other words, as the encoder rotates faster, the pulse frequency increases […]

Roller screw actuators: Design and applications

Electromechanical actuators come in many varieties, with common drive mechanisms being lead screws, ball screws, and roller screws. When a designer or user wants to transition from hydraulics or pneumatics to electromechanical motion, roller screw actuators are usually the best choice. They provide comparable performance characteristics to hydraulics (high force) and pneumatics (high speed), in […]

How are complementary signals used to mitigate encoder noise?

Electrical noise is a common problem that occurs during the transmission of an incremental encoder’s signal to the receiving electronics, especially when the cable lengths are very long. Stray electromagnetic fields or currents induce unwanted voltages into the signal. These voltages can cause the receiver to make false counts, producing errors in the position or […]

IKO MX series linear roller bearings now include dust protection

IKO International is building on its standard MX series of linear roller bearings to include special features for environments that are sensitive to metal chips, dust, and other contaminants. Dust protection A dust protective C-Wiper can be mounted to the outside of the end seal, ensuring operation in environments where metal chips are spattering. After […]

What is a 12 volt linear actuator?

Linear actuators are typically characterized by their drive mechanism – belt drive, ball or lead screw drive, pneumatic drive, etc. But it’s not unusual for rod style electric actuators to be classified by the input voltage – commonly 12 or 24 volts – of their integrated motors. These actuators provide thrust force, much like a […]

What is a wound rotor motor?

A wound rotor motor is a variation of the three-phase induction motor, designed to provide high starting torque for loads with high inertia, while requiring very low current. Wound rotor motors are also referred to as “slip ring motors.” The stator of a wound rotor motor is the same as a typical induction motor, but […]

What are can stack linear actuators?

Can stack linear actuators are based on can stack stepper motors, which are a form of permanent magnet steppers that consist of two stators (and therefore two coils) stacked on top of each other. The poles of each stator are “claw tooth” design and are offset from each other by one-half of the pole pitch. […]

Cyber dynamic linear actuators with integrated ball screw from WITTENSTEIN

Ideal for packaging, food & beverage, medical and semiconductor applications, the latest addition to the cyber® dynamic line from WITTENSTEIN cyber motor offers maintenance-free precision positioning in compact space. As part of its cyber dynamic line product series, WITTENSTEIN cyber motor has launched a new series of linear actuators designed with an integrated ball screw […]

When are voice coil actuators the best linear motion option?

Voice coil actuators are most commonly used for micro- or nano-positioning applications, with strokes from 10 nm up to 100 mm. In addition to very precise positioning capabilities, voice coil actuators provide extremely smooth movement. They’re often paired with air bearings, crossed-roller guides, or linear shafts and round bearings to provide assemblies that are backlash-free. […]

What is linear behavior for DC motors?

When the term “linear behavior” is used to describe a system, it implies that the system’s output is directly proportional to the input.  Unlike their wound-field counterparts, permanent magnet DC (PMDC) motors exhibit linear behavior. The use of permanent magnets means PMDC motors don’t need separate field excitation, and therefore, don’t experience the electrical losses […]

What does RMS mean, and how does it apply to linear systems?

RMS, or root mean square, is a statistical term that is used for determining the mean (or average) of a set of values. It’s especially useful when the values vary as a function of time. The technical definition of root mean square is the square root of the mean of all the squares in a […]

What are auto tuning methods for servo drives?

Tuning a servo system is a complex and iterative process. It typically requires tuning multiple control loops, each with its own gains (proportional, integral, and/or derivative) to be adjusted, not to mention additional parameters such as acceleration and velocity feed-forward gains and filters to reduce oscillations. While manual tuning has been the predominant method for […]

What is torque, and why is it important in linear motion?

Although torque refers to rotational motion, it is a fundamental concept in linear motion applications. Rotary motors produce torque, and when this torque is transmitted to a drive system – such as a screw, belt and pulley, rack and pinion, or chain and sprocket – it’s converted to linear motion. Torque is the rotational equivalent […]

Where are digital servo drives used?

The original servo drives were analog types that operate on ± 10 volt inputs, but digital servo drives that operate over fieldbus networks now dominate the market. The primary difference in construction between digital and analog drives is that a digital drive includes a microprocessor, which carries out computations to determine the output control signal […]

Where are analog servo drives used?

The purpose of a servo drive is to convert low-power signals from the controller to high-power signals to the motor, instructing it to produce the desired torque or velocity. Servo drives (also referred to as servo amplifiers) can operate on either analog or digital input signals. Analog servo drives receive ± 10 volt analog signals […]

How to calculate acceleration

When sizing a linear system, a lot of attention is given to velocity, but the effects of acceleration on the system and its components are often more significant than those due to velocity. Acceleration is most associated with the move profile and how to best achieve the required travel in the specified time, but it […]