Resolver vs encoder pdf

Both resolvers and encoders measure the rotary position of a shaft, converting a mechanical position to an electrical signal, but what are the differences between them and which should you use. Some encoders combine an incremental encoder output with an absolute encoder output. In addition, the conversion rate of the rdc limits a resolver s maximum speed, and resolvers lose some accuracy when the application encounters rapid speed changes, as is often the case with servo motors. And unlike other variablereluctance resolvers, the rotasyn utilizes a constant air gap so it is less sensitive to eccentricity and stray magnetic fields. There are many types of motor control, but this article discusses two that implement an analog signal chain around the position sensor. It is ultrathin absolute type angle detector with a strong high reliability in high temperature, vibration and shock. Higher resolution resolvers are produced with additional pairs of coils.

The word encoder can be a confusing term to those who have never used them. Rotary encoder output signals can be emulated, for example. The resolver amplitude modulates the vac input in proportion to the sine and the cosine of the angle of mechanical rotation. Synchro and resolver engineering handbook contents page section 1. Encoders produce pulses indicating movement over a short distance. Vw3a3423 resolver interface module schneider electric. The absolute encoders are more expensive than the incremental encoders, therefore, a pricefeature tradeoff may be worth considering. Resolvers are absolute analog rotary encoders which are ideal for harsh environments.

Oct 09, 2015 in addition, the conversion rate of the rdc limits a resolvers maximum speed, and resolvers lose some accuracy when the application encounters rapid speed changes, as is often the case with servo motors. Converting resolver interface to incremental encoder interface. With no onboard electronics, resolvers can survive extreme temperatures and tolerate shock and vibration, making resolvers suitable in applications where encoders would fail. Initial homing to a reference point is therefore inevitable in all positioning tasks, both upon start up of the control system and whenever power to the encoder has been interrupted. Position sensors choosing the right sensor zettlex. On the next page, youll find quantified ratings that reflect the comments in this paper. The environmental integrity of a brushless resolver. Resolvers and tachogenerators give information in analog form. Pros and cons encoders encoders can give higher resolution beyond 16bit, but they fall short under extreme environmental conditions of temperature, humidity or vibration. It compares classical resolver vs variable reluctance resolver and mentions difference between them. Resolver this decision is primarily based on the operating environment. How to choose the right feedback option this white paper summarizes the difference between encoder and resolver feedback technology, helping the reader understand which type of motion control is right for their application. The resolver is a sensor used in a servo drive system to give information.

With the optical transformation, a linecoded disc made of metal, plastic or glass and positioned on a rotary bearing interrupts the infra red light ray emitted by gallium arsenid sender diode. Encoders are on ac servo motors, and resolvers for dc servo motors. Resolver is a synchro whose rotor is mechanically driven to translate rotor angle into electrical information corresponding to the sine and cosine of rotor angle. It is considered an analog device, and has digital counterparts such as the digital resolver, rotary or pulse encoder. A typical resolver has three windings a primary winding and two secondary windings. How are incremental encoders different than resolvers. The weak point of an optical encoder can be that a part of the accompanying electronics is placed close to the sensor so that temperature influence can be important. Pros and cons encoders encoders can give higher resolution beyond 16bit, but they fall short under extreme environmental. Being simple rotary transformers, the resolvers can take much more abuse than optical encoders and exhibit no significant wear or aging. Updated on 11519 encoders and resolvers essentially do the same thing. Higher resolution will provide better more stable velocity at slower speed. Doubt between g120 with encoder feedback and s120 with. Incremental encoders output pulses each time and only when the shaft is turned or linear target is moved. The environmental integrity of a brushless resolver is unchallenged.

Closedloop motor control systems continue to answer this question, as there tends to be a closedloop system implemented wherever a motor spins. Amcis resolver based encoder is a field programmable rotary shaft encoder, possessing unbelievable flexibility. Our integrated circuits and reference designs help you create highly accurate and robust position and speed feedback for servo, cnc and robotics drives. In other words, when an absolute encoder is powered up it will report its angle without the need for any reference information or movement. It is also called a sinecosine generator and synchroresolver. Admotecs patented position sensor technology resolver technology produces a resolver with fewer parts, a solid rotor without slots, windings, or the need for a rotating transformer. An introduction to rotary resolvers and encoders introduction is your motor spinning at the intended rate.

The function of the resolver is to resolve a vector into its components sine and cosine. Absolute incremental and absolute encoders perform similar functions, but have dissimilar outputs. The rotary transformer device used to measure degrees of rotation is known as resolver. Both encoder and decoder are combinational logic circuits, however, one of the crucial difference between encoder and decoder is that an encoder provides binary code as its output. This implicit arc tangent calculation is based on the trigonometric identity sin. Resolvers are successfully used for precise control in many applications.

Our integrated risk management software helps organizations reduce the frequency and severity of negative events. Mar 22, 2012 produced with cyberlink powerdirector 10. Flexibility if at some point in the future more performance or positioning accuracy becomes necessary, it will be much easier to upgrade an encoder based system. The shaft encoder generates a signal for each incremental change in position. In recent years, a new generation of device has become popular the inductive encoder. Whats the differences between a resolver and a synchro. Resolver covers a wide range of sectors and helped millions of consumers raise issues with thousands of companies. Inductive encoders can be thought of as a hybrid of a resolver and an optical encoder. Resolvers can operate in ambient temperatures up to 200c and higher. This industrystandard singleturn resolver transducer has often been imitated yet never duplicated. Resolvers also have a reputation for being heavy, bulky and expensive.

Resolvers vs encoders for motion control the phrase more precise control would generally drive the solution towards an encoder over a resolver. It is also called a sinecosine generator and synchro resolver. Such encoders can be either absolute or incremental. Synchro and resolver white paper jd technologies, llc. An introduction to rotary resolvers and encoders texas instruments. Position and speed feedback devices for variable speed drives. Though the brush encoder can theoretically attain equivalent performance, its useful operating life, at very high resolutions, is severely limited by noise and position2 figure 1. Resolvers and encoders are both devices that measure the rotary position of a shaft by converting mechanical motion into an electrical signal. For applications that involve shock loads, vibrations, or high temperatures, resolvers are a more robust solution.

The windings are created using copper wire and are formed on the resolvers stationery element the stator. The primary wire acts as the input for an ac drive signal and each of the secondary windings are used as pick up or receive windings. Resolver basics,types resolver to digital converter. Resolvers integrated cloud platform supports risk and incident management process to protect your employees, customers, data, brand, inventory and shareholders. Its primary function is to convert rotary motion into useful information. Forming the rotor core into a special shape and changing the width of the gap between the rotor core and the stator core generates changes in the amplitude of the. As feedback devices, resolvers can be used as alternatives to both incremental encoders and absolute encoders. Resolver electrical, a type of rotary electrical transformer used for measuring degrees of rotation a rotary encoder converts rotary position to an analog e. Vs vc the ratiometric tracking converter performs an implicit arc tangent calculation on the ratio of the resolver signals by forcing a counter to track the position of the resolver. Use our guide below to find your reliance resolver part number and click on the dynapar replacement model to visit our online configuration tool. Both of them are used in agle measurement of a shaft, but its not clear to me when to use one or the other and what are the benefits of each of them and disadvantages. For comparison, figures 24, 25, and 26 illustrate the components required to measure rotary displace ment with the encoder, resolver, and potentiometer.

Resolver vs encoder optical resolution accuracy and. It can interchange rectangular and polar coordinates. Encoder accuracy is typically in the range of 20 arcseconds, which is much better than the 3 arcminute range of resolver accuracy. How they integrate into a system and the format of the feedback are where key differences ariseaside from the fact that there is another type of encoder made to measure linear movement. The singlsyn has higher reliability and can be produced at lower cost as it does not have a coil on its rotor. On the contrary, a decoder accepts binary code as its input. Unlike an encoder, a resolver can be used without problems in a hot environment with high levels of vibration and contamination. I understand a resolver is a kind of synchro, and a synchro has 3 windings, 120 degrees phased from each other, while a resolver has only 2, 90 degrees phased.

Encoder output z ord9 48 o output data output select 9 for parallel angle and velocity ors 9 o exciter preamplifier output osin 43 o resolver sine output outa 1 o output incremental encoder, output a outb 2 o output incremental encoder, output b outz 64 o output incremental encoder, output z pbkg 27 p ground pgnd 8 p power ground. This page mentions basics of resolver to digital converter. Vr type resolver singlsyn products resolverssynchros. In fact, using an encoder as a tachometer does offer the benefit of improved dynamic response, you do not need to wait for a full rotation to update your measurement and can determine the speed of a motor with greater accuracy. Absolute encoders continuously report their position as a digital message of 1s and 0s, whether the encoder is moving. Resolver free online tool for complaints and claims. Learn how they work, their design and discover applications. The application of dry food packaging however might tend to drive it back towards a resolver. A resolver is an electromagnetic transducer used in a wide variety of position and velocity feedback applications. Dynapar offers direct replacements for resolvers used in the reliance automax plc system with great prices and fast lead times. The primary winding is located on the shaft of the resolver and is called the rotor. In addition, we offer electrical circuits for evaluating the resolvers analogue output signals. As discussed, the inductive encoder has numerous advantages versus the resolver particularly size and weight.

Our robust interface solutions for incremental and absolute encoders support all industry standards for drives like endat2. A resolver is a type of rotary electrical transformer used for measuring degrees of rotation. By contrast a resolver can have its electronics tens of meters away. Data sheet encoder and encoder cable comparison dt. Accuracy an encoder will be more accurate than a resolver and its associated conversion process. Difference between encoder and decoder comparison chart. What is difference between resolver and rotary encoder pls guide. Installation and wiring guide encoder products company. Resolver customers are secure and resilient, ready to respond to every threat and opportunity. Similar to a motor in design with a rotor with a reference winding, a resolver also has a stator with two secondary windings. For this reason, the choice of tachometer vs encoder isnt quite as clearcut as you might expect.

Speed and position feedback devices nidec netherlands. Each time the encoder is powered on it begins counting from zero, regardless of where the shaft is. Resolver can help you make a complaint or claim for free. In summary, the application should be the guide when deciding between resolver or encoder feedback. Resolvers vs encoders for motion control heidenhain.

Inductive encoders or incoders use the same basic physics as a resolver but are less costly, lighter, more compact and more accurate. The most simple resolver, the fourpole, is illustrated in figure 23. An encoder application will require only the feedback element to be. I have a doubt between g120 with encoder feedback and s120 with resolver feedback, i am working in a migration project and the machine has frequency converters with resolver feedback, i need to change this converters to sinamics converters, i can read resolver feedback with s120 and smc10, but i dont have the software configurator for this devices, if i am not wrong is simotion scout. The difference between resolver vs encoder is also mentioned. Control electronics and environmental conditions are the two biggest factors to consider when both of these are answered, the choice becomes clear. A linear encoder similarly converts linear position to an electronic signal. The core parameters determined are speed, rate, velocity, distance, position, or direction. A06b0859b200 fanuc ac spindle motor modell alpha 22 test and repair by ltd duration.

When a reference ac input voltage, set at a constant frequency, is induced in the. The outputs v1, and v2 depend on the angles between the rotor and the stator coils. Apr 12, 2011 updated on 11519 encoders and resolvers essentially do the same thing. T e c h n i c a l w h i t e p a p e r 1 resolvers versus encoders. Before discussing the signalchain solution for a resolver, consider its basic operation in figure 1. Phase offset channel a channel b channel n reference pulse zero signal shaft turning clockwise cw seen from front of encoder possible evaluation of twothreechannel shaft encoders measuring pitch the resolution of a twochannel shaft encoder can be doubled or quadrupled in the subsequent circuitry. Using our downstream electronics, the analogue signal can also be digitized. Mark howard, general manager, zettlex uk ltd file ref. This white paper summarizes the difference between encoder and resolver feedback. The resolver is sometimes known as an analog trigonometric function generator or a control transmitter. Table of contents nasa infrared telescope facility. Unlike conventional optical or magnetic rotary encoder with internal temperaturelimiting electronics, the resolver is similar to a transformer in construction and does not incorporate any electronics. The technology has been developed and the systems based on it are unsurpassed in reliability and cost effectiveness.