The Hall effect is an outcome of the Lorentz force at work. When a thin conductor (or semiconductor) has a steady flow of current running through it and a magnet is placed so that its magnetic field runs perpendicular to this current, the magnetic field of the current reacts to the magnetic field of the […]
What to consider when choosing a rotary encoder
Controlled servo drives are used in many areas of automation technology, converting, printing, handling, and robotics, including production machines and machine tools. The selection of a rotary encoder or encoder technology for use within the system depends on the accuracy requirements of the application and whether the application will use position control, velocity control, or both. […]
Why do servo drives use PWM and how does it work?
The basic function of a servo drive is to convert, or amplify, low-power signals from the controller into higher-power signals to be delivered to the motor windings. Servo drives (also referred to as servo amplifiers) can be either linear or switching types, depending on how power is delivered to the motor from the switching devices […]
When is dither helpful in motion control systems?
Dither is one of several terms used to describe small, rapid, back-and-forth movements of an object. Depending on the context, when the term “dither” is used in motion control systems, it can refer to purposeful, commanded movements or to unintended, unwanted motion. In some motion systems, dither is purposely induced to reduce the effects of […]
What is an observer in motion control and how does it affect performance?
A servo control loop uses sensor feedback to determine whether the system’s actual state (position, velocity, or torque) matches the commanded state. But sensors feedback isn’t perfect — even high-quality encoders and sensors can introduce noise, phase lag, and other errors in measurement. One way to improve the feedback of a servo control system is […]
What type of encoder can measure speed?
Encoders and resolvers are used to track the angular or linear position of an object, such as a motor shaft (angular measurement) or a linear actuator (linear measurement). And with the addition of a clock signal, encoders and resolvers can also be used to measure the speed of the object. A resolver uses a rotor with […]
What’s the difference between radial and axial ring encoders?
A traditional rotary encoder measures the position or speed of a rotating shaft, with mounting via a coupling or a hollow bore that allows the encoder to fit over the shaft. But not all rotating components have a shaft to which the encoder can mount. For example, direct-drive rotary motors — also known as torque motors, […]
What are Sawyer motors and where are they used?
Originally named for Bruce Sawyer, who patented the design in 1968, Sawyer motors are a type of planar motor, and are sometimes referred to as “dual-axis linear stepper motors” since they use stepper motor technology and the moving part can travel in both the X and Y directions. Like other planar motor designs, Sawyer motors […]
Updated MEPS: Regulation (EU) 2019/1781 for motors and drives takes effect in July 2021
In 2011, the EU implemented minimum efficiency performance standards (MEPS) for electric motors used in residential, commercial, and industrial applications with Commission Regulation (EC) 640/2009, which was implemented in three stages through 2017, and its amendment Regulation (EU) 4/2014. In October 2019, Regulation (EC) 640/2009 was replaced with Commission Regulation (EU) 2019/1781, which outlines updated efficiency […]
Customized and reliable stepper motors address HVAC damper application extremes
In any HVAC (heating, ventilation, and air conditioning) system, dampers are used to regulate airflow inside the ducts. In some systems, manual dampers allow personnel to turn a handle on the outside of a duct. But if you have to regulate airflow on a constant basis, you’ll need automatic dampers with electric or pneumatic motors […]
What are electromagnetic power-off brakes and where are they used?
Power-off brakes are commonly used in motion control applications for stopping or holding a load (or both), especially on vertical axes or for emergency stop functionality in servo applications. Power-off brakes are so named because the brake is engaged when power is removed from the system — either intentionally or accidentally. (Power-off brakes are also […]
Low-profile kit-style limited angle torque motor
The TMR-075-16-001-2 limited angle torque motor utilizes a toroidally wound, stationary coil assembly with a two-pole permanent magnet rotor to generate torque. The rare earth permanent magnet rotor always has an even number of poles, with two to six poles. The maximum angular excursion with a two-pole rotor is 180º, but the torque will drop […]
What is Single Pair Ethernet (SPE) and how is it used in industrial applications?
Single Pair Ethernet (SPE) is a technology that provides Ethernet transmission over a single pair of copper wires, while also transmitting power to connected devices via Power over Data Line (PoDL). Single Pair Ethernet was initially developed to meet the demands of the automotive industry — smaller, lighter cables and connectors for transmitting data from […]
How to calculate continuous and peak torque values for servo applications
One of the most important tools for sizing a servo motor is the motor’s torque-speed curve, which shows the combinations of torque and speed that the motor can produce in two operating zones — continuous operation and peak, or intermittent, operation. To prevent thermal overload of the motor — and the drive — it’s important to […]
What’s the current status of AGMA and ISO gear quality standards (and why are they so confusing)?
Gear quality standards developed and published by the American Gear Manufacturers Association (AGMA), have dominated gear manufacturing in the U.S. market since the 1960s. But in the 1990s, AGMA began working with the International Organization for Standardization (ISO) to update and harmonize gear quality standards, with several versions of both AGMA and ISO standards published […]
What is a direct drive in the context of motion applications?
In the most common motor-driven systems, the motor is coupled to the load being moved by a mechanical transmission element — a belt, chain, rack and pinion, ball or lead screw, or even simply a gearbox. But some linear and rotary motion systems do away with mechanical transmission elements and couple the load directly to […]
What are the performance benefits of 5-phase stepper motors?
Stepper motors are often categorized by the number of phases in their construction, with 2-phase and 5-phase versions being common designs. And although 2-phase versions are more widely adopted, 5-phase stepper motors offer performance advantages that make them the preferred choice in some applications. The basic construction of a hybrid stepper motor includes two rotor […]
What are breakpoints and how are they used in motion control?
In computer programs, breakpoints are functions within the code that help with monitoring and debugging the program. The programmer can mark, or flag, a line of code as a breakpoint, and when the program encounters the breakpoint marker, it pauses before executing that line of code. This allows the programmer to inspect variables, I/O status, […]
What’s the difference between NEMA and IEC motor starters?
A motor starter is a device that controls power to a motor for starting, stopping, reversing, and in some cases, protecting the motor from overload current. Although sometimes referred to as contactors, motor starters actually consist of a contactor and a thermal overload relay. The contactor is an electromechanical device based on a coil and […]
What are eddy currents and how do they affect motor performance?
One of the electromagnetic principles that governs the operation of an electric motor is Faraday’s law, which states that when the magnetic environment of a coil of wire is changed — whether by moving the magnet and coil relative to each other or by changing the magnetic field — a voltage, or electromotive force (EMF), will […]
What are inductive encoders and how do they differ from resolvers and LVDTs?
Position measuring devices that rely on the principle of mutual induction include resolvers, linear variable differential transformers (LVDTs), and inductive encoders. Two of these technologies — resolvers and LVDTs — are based on the construction and operation of a transformer. In the case of an LVDT, voltage is applied to a primary winding and induced in […]
What are double- and triple-stack hybrid stepper motors ?
Of the three primary stepper motor designs — permanent magnet, variable reluctance, and hybrid — hybrid stepper motors are arguably the most popular in industrial applications, combining the best performance characteristics of permanent magnet and variable reluctance types. Hybrid stepper motors are constructed with a rotor made of two sections, or cups, with a permanent […]
What are different ways to express a gear ratio?
In motion control systems, gears are used to change the torque and speed delivered by a motor to a driven component. Depending on how the gears are arranged, they can either increase the delivered torque and decrease the output speed (the most common arrangement in motion control applications) or decrease the delivered torque and increase […]
Absolute encoder interfaces: Differences between SSI, BiSS, Hiperface, and EnDat
Absolute encoders can communicate with controllers through parallel or serial wiring, over a fieldbus, or via an Ethernet-based protocol such as EtherCAT. Of these options, serial communication is a simpler solution than parallel wiring (which requires a twisted pair of wires for each bit of output) and is well-suited for applications that aren’t complex enough […]
What are multi-stage gearboxes and when are they used?
Gearboxes are commonly used in motion control applications to change the output speed and torque from a motor to a driven component. By using a smaller gear with fewer teeth (commonly referred to as a pinion) to drive a larger gear with a higher number of teeth, the torque delivered to the load is increased while […]