Resolvers vs. Encoders08/30/2018To monitor the speed and position of your motor and provide that data to the controller, you’ll need a feedback device. The resolver or encoder is coupled to the shaft of the motor and has circuitry to translate the mechanical rotation to an electrical signal that can be interpreted by the controller.What is a resolver? A resolver transmits an analog signal. It is essentially a rotary transformer with one primary winding and two secondary windings that are phased 90 mechanical degrees. The resolver output requires control inputs and logic that can interpret analog signals. One of the specifications in a resolver is its number of speeds. The number of speeds is equivalent to the number of amplitude modulated sinusoidal cycles in one revolution of the resolver. Multiple speed resolvers are achieved by increasing the number of magnetic poles in the rotor and stator equally. The maximum number of speeds is limited to the size of the resolver, and is typically done to increase the accuracy. Resolvers lend themselves to maximum duty applications because of their simple component similarity to electric motors (windings, laminations, bearings, and carrier). The lack of optics and precision alignment increases shock and vibration capabilities. The lack of both optics and solid state electronics allows for use in high radiation environments. What is an encoder? Similar to resolvers, encoders are also electromechanical devices that convert mechanical motion into an electronic signal. However, unlike a resolver, an encoder transmits a digital signal rather than analog. Incremental encoders rely on external electronics to interpret the position based on the count of the events that occurred on that device. The outputs for incremental encoders can come in the form of a single square wave A, phased square waves A and B to determine direction of rotation, or phased square waves and an index or one pulse per revolution A, B, and Z. The concept of phasing square waves to determine rotational direction is often referred to as “quadrature”. The means of achieving an incremental signal are typically referred to as the encoder engines. The two primary encoder engine categories are optical and magnetic. In both engines, similar sensor alignment is performed to provide output compatibility.The Fanuc servo motor for example uses several different varieties of their own encoders including: Pulsecoder A, B, B2, C, Pulsecoder Alpha I8, A8, I64, A64, 1000A, I64i, A64i, 1000iI, 1000iA, Pulsecoder Beta I32B, A32B, I64B, A64B, and A128i to name a few. If you need service on any of your Fanuc servo motors, give a call at 800-732-4695 to the repair experts at PES. Back To Blog
Resolvers vs. Encoders08/30/2018To monitor the speed and position of your motor and provide that data to the controller, you’ll need a feedback device. The resolver or encoder is coupled to the shaft of the motor and has circuitry to translate the mechanical rotation to an electrical signal that can be interpreted by the controller.What is a resolver? A resolver transmits an analog signal. It is essentially a rotary transformer with one primary winding and two secondary windings that are phased 90 mechanical degrees. The resolver output requires control inputs and logic that can interpret analog signals. One of the specifications in a resolver is its number of speeds. The number of speeds is equivalent to the number of amplitude modulated sinusoidal cycles in one revolution of the resolver. Multiple speed resolvers are achieved by increasing the number of magnetic poles in the rotor and stator equally. The maximum number of speeds is limited to the size of the resolver, and is typically done to increase the accuracy. Resolvers lend themselves to maximum duty applications because of their simple component similarity to electric motors (windings, laminations, bearings, and carrier). The lack of optics and precision alignment increases shock and vibration capabilities. The lack of both optics and solid state electronics allows for use in high radiation environments. What is an encoder? Similar to resolvers, encoders are also electromechanical devices that convert mechanical motion into an electronic signal. However, unlike a resolver, an encoder transmits a digital signal rather than analog. Incremental encoders rely on external electronics to interpret the position based on the count of the events that occurred on that device. The outputs for incremental encoders can come in the form of a single square wave A, phased square waves A and B to determine direction of rotation, or phased square waves and an index or one pulse per revolution A, B, and Z. The concept of phasing square waves to determine rotational direction is often referred to as “quadrature”. The means of achieving an incremental signal are typically referred to as the encoder engines. The two primary encoder engine categories are optical and magnetic. In both engines, similar sensor alignment is performed to provide output compatibility.The Fanuc servo motor for example uses several different varieties of their own encoders including: Pulsecoder A, B, B2, C, Pulsecoder Alpha I8, A8, I64, A64, 1000A, I64i, A64i, 1000iI, 1000iA, Pulsecoder Beta I32B, A32B, I64B, A64B, and A128i to name a few. If you need service on any of your Fanuc servo motors, give a call at 800-732-4695 to the repair experts at PES.