jump to navigation

New Size 20 Rotary Shaft Encoder from Quantum Devices October 8, 2014

Posted by Servo2Go.com in New Product Press Releases.
Tags: , , , , ,
add a comment

Quantum Devices, Inc. model QDH20 provides an improved feedback solution in applications typically using a standard size 20 package.  The QDH20 provides encoder feedback in standard industrial mounting configurations with superb mechanical and environmental protection.

Outputs consist of a quadrature A & B with reference pulse Z as a standard feature.  The output can be configured with either the industrial standard 5 to 26 volt OL7272 line driver or open collector outputs.

Quantum QDH20 Encoder

Quantum QDH20 Encoder

The QDH20 features two heavy-duty bearing sets holding the output shaft, and two more bearings along with an integral flexible spring mount to isolate the working pieces of the encoder from mechanical stresses.

Features include:

  • 500 kHz Fundamental Frequency Response
  • High Operating Temperature Option (100 C)
  • Resolutions up to 5000 lines per revolution direct read
  • Flange and Servo Mount Options
  • 0.375″ shaft diameter
  • High Noise Immunity

 

More information on the QDH20 optical encoder from Quantum Devices can be found at the link below-

https://servo2go.com/product.php?ID=100132&cat=

For more information, please contact:

Editorial Contact:

Warren Osak
sales@servo2go.com
Toll Free Phone:  877-378-0240
Toll Free Fax:   877-378-0249
www.servo2go.com

 

Tags:  Encoder, Incremental Encoder, Single-Ended Encoder, Differential Encoder, Servo2Go, Quantum Devices

What is meant by Rotary Incremental Encoder Index Pulse “gating”? June 11, 2014

Posted by Servo2Go.com in Technical Support Information.
Tags: , , , , , , , ,
add a comment
Quantum Devices Optical Encoder

Quantum Devices Optical Encoder

Gating refers to the width of the Z (index) pulse relative to the A and B channels. With ungated devices the edges of the Z pulse have no hard relation to A & B.

Gating to channel A, requires the Z pulse to be high once per revolution and only when A is high.

Gating to channels A&B high requires the Z pulse to be high once per revolution and only when A AND B are high.

Gating to A creates a Z pulse roughly 180 Electrical Degrees in duration while gating to A&B creates a Z pulse roughly 90 Electrical Degrees in duration.

Gating to a smaller duration increases the precision of the Z pulse, but also requires the motion system to be able to read the Z channel at a faster rate.

Gating is sometimes required by certain drive/amplifier/controller manufacturers.

QD145 Z (Index Pulse) Specifications:

incremental-encoder-gating1
Ungated Z
Z-A/A-Z min = 0 Electrical Degrees
Z-A/A-Z max= 225 Electrical Degrees
Z width min = 180 Electrical Degrees
Z width Max = 540 Electrical Degrees

Z Gated to A
Z width min = 135 Electrical Degrees
Z with max = A true

Z Gated to A&B
Z width min = 45 Electrical Degrees
Z width Max = A&B true

incremental-encoder-gated1

Ungated Z
Z true over A&B> 45 Electrical Degrees
Z-A&B/A&B-Z min = 0 Electrical Degrees
Z-A&B/A&B-Z max= 315 Electrical Degrees
Z width min = 180 Electrical Degrees
Z width Max = 540 Electrical Degrees

Z Gated to A
Z width min = 135 Electrical Degrees
Z with max = A true

Z Gated to A&B
Z width min = 45 Electrical Degrees
Z width Max = A&B true

More information on ‘Quick Ship’ Industrial Rotary and Modular Shaft Encoders can be viewed at-

http://servo2go.com/supplier.php?id=1057843244

For more information please contact:

sales@servo2go.com
Toll Free Phone:   877-378-0240
Toll Free Fax:       877-378-0249
www.servo2go.com

 

Tags:  Encoder, Incremental Encoder, Absolute Encoder, Single-Ended Encoder, Differential Encoder, Servo2Go, Quantum Devices

 

 

The no assembly hassle industrial optical encoder from Quantum Devices May 7, 2014

Posted by Servo2Go.com in New Product Press Releases.
Tags: , , , , , ,
add a comment

The QPhase™ QD200 has been designed to eliminate the assembly hassle and hidden cost of installing modular or kit encoders onto OEM products.  The QD200 is a complete operational unit with an integral dual ABEC 5, ball bearing, insert molded hollow shaft support that provides the mechanical stability for this low profile (0.93” high by 2.00” diameter) high resolution encoder package.  Using our proprietary sensing technology we are able to obtain an incremental, 5000 PPR, plus Index pulse, without the use of interpolation schemes.  The stainless steel flexible spring mount provides for 30° rotational adjustment to permit precise commutation alignment and has been designed to allow for more motor tail shaft run out than typical modular or kit type units can tolerate.

Quantum Devices QD200 Optical Encoder

Quantum Devices QD200 Optical Encoder

Product options include: 120° C continuous ambient operating temperature, 4 to 8 pole three phase commutation signals for brushless motors, 5–26 VDC operating input voltages, high voltage line driver outputs on both incremental and commutation lines and standard resolutions from 500 PPR to 5000 PPR derived directly from the encoder disc.

More information on the QD200 optical encoder from Quantum Devices can be found at the link below-

https://www.servo2go.com/product.php?ID=100130&cat=

For more information, please contact:

Editorial Contact:

Warren Osak
sales@servo2go.com
Toll Free Phone:  877-378-0240
Toll Free Fax:   877-378-0249
www.servo2go.com

 

Tags:  Encoder, Incremental Encoder, Absolute Encoder, Single-Ended Encoder, Differential Encoder, Servo2Go, Quantum Devices

 

Understanding Incremental Encoder Signals April 29, 2014

Posted by Servo2Go.com in Technical Support Information.
Tags: , , , , , ,
add a comment

Which incremental encoder wires should I use?

Channels A & B (Incremental Channels)

Use only A (or only B) for an RPM or counting applications where the rotation is either unidirectional, or where you don’t need to know direction.

Use A and B together to know direction.  After two low pulses the next high pulse indicates direction.  This is due to the phasing offset between A and B of 90 electrical degrees, placing the signals in what is known as quadrature.

These signals can also be used to set up an up/down counter.

Index pulse, also known as Z, marker, or I

Index pulse is a pulse that occurs once per rotation.  It’s duration is nominally one A (or B) electrical cycle, but can be gated to reduce the pulse width.

The Index (Z) pulse can be used to verify correct pulse count.

The Incremental Encoder Index pulse is commonly used for precision homing.  As an example, a lead screw may bring a carriage back to a limit switch.  It is the nature of limit switches to close at relatively imprecise points.  This only gives a coarse homing point.  The machine can then rotate the lead screw until the Z pulse goes high.

For a 5000 line count encoder this would mean locating position to within 1/5000 of a rotation or a precision of .072 Mechanical Degrees.  This number would then be multiplied against lead screw travel.

Commutation (UVW) signals are used to commutate a brushless DC motor.  I always like to compare these signals to that of a distributor in a car.  The commutation (sometimes called “Hall”) signals tell the motor windings when to fire

You would need to have encoder commutation signals if the motor you are mounting the encoder to has a pole count and there is no other device doing the work of commutation.  It is important to note that commutation signals need to be aligned or “timed” to the motor.

Single ended vs differential

These terms refer not to the waveforms of signals, but instead to the way the signals are wired.

Single ended wiring uses one signal wire per channel and all signals are referenced to a common ground.

TTL and Open Collector are types of single ended wiring.

Differential wiring uses two wires per channel that are referenced to each other.  The signals on these wires are always 180 electrical degrees out of phase, or exact opposites.  This wiring is useful for higher noise immunity, at the cost of having more electrical connections.

Differential wiring is often employed in longer wire runs as any noise picked up on the wiring is common mode rejected.

RS-422 is an example of differential wiring.
More information on ‘Quick Ship’ Industrial Rotary and Modular Shaft Encoders can be viewed at-

http://servo2go.com/supplier.php?id=1057843244

For more information please contact:

sales@servo2go.com
Toll Free Phone:   877-378-0240
Toll Free Fax:       877-378-0249
www.servo2go.com

Tags:  Encoder, Incremental Encoder, Absolute Encoder, Single-Ended Encoder, Differential Encoder, Servo2Go, Quantum Devices

Absolute encoders. A short primer January 15, 2014

Posted by Servo2Go.com in Technical Support Information.
Tags: , , , ,
add a comment
Reprint of Design World 2012-08-09 Article

Encoders can be either absolute or incremental.  Absolute encoders have a unique code for each shaft position. Or in other words, every position of an absolute encoder is distinctive.  The absolute encoder interprets a system of coded tracks to create position information where no two positions are identical.  Another feature is that absolute encoders do not lose position whenever power is switched off.  Since each position is distinctive, the verification of true position is available as soon as power is switched on.  It is not important to initialize the system by going back to a home base for a reference.

Absolute Encoder Codewheel

Absolute Encoder Codewheel

Absolute encoders can be either single-turn or multi-turn.  Single-turn encoders are well suited to short travel motion control applications where position verification is needed within a single turn of the encoder shaft.  Multi-turn encoders, on the other hand, are better for applications that involve complex or lengthy positioning requirements.

Absolute encoders have a number of advantages.  First is the non-volatility of memory.  An absolute encoder works as a non-volatile position verification device.  True position is not lost if power is lost or the system moves while power is switched off.  A continuous reading of position is not needed.  This is specifically useful in those applications, such as satellite-tracking antennas, where position verification is key.

Absolute encoders also provide programming flexibility.  By removing the need for system homing, the encoders can be controlled to give positioning programs based on setting up reference from point-to-point, rather than from a home position.  Additionally, a microprocessor interface module allows for programming various operating parameters, such as resolution.

Safety is another benefit. In some applications where a loss of position could lead to operator injury or machine damage, an absolute encoder automatically provides position verification when the power is switched on.  Absolute encoders also have good immunity to electrical noise.  The device determines position by frequently reading a coded signal. Stray pulses from electrical noise will not build up and accurate position is presented again on the next reading.

For more information, please contact:

EDITORIAL CONTACT:

Warren Osak
sales@servo2go.com
Toll Free Phone:   877-378-0240
Toll Free Fax:       877-378-0249
www.servo2go.com

Tags:  Encoder, Absolute Encoder, Single-turn encoder, Multi-turn encoder

Finding the Index on an Incremental Encoder with a DMM January 31, 2013

Posted by Servo2Go.com in Product Video's, Technical Support Information.
Tags: , , , , ,
add a comment

Sometimes you don’t have the right tools to do the job.

Lets say you needed to identify where the index pulse was firing on your incremental encoder, but you left your oscilloscope in your other jacket pocket, and now all you have on hand is a DMM.

Well fear not, finding the index with a multimeter is possible although a bit tedious.

The index fires once per revolution and at higher line counts this makes it VERY easy to miss.   Since there is some delay in a multimeter’s display time, you will need to rotate the encoder very slowly to catch a change in voltage level.

The Blue box has a nine-volt battery inside that I regulated down to 5Vdc for the encoder power.   I have pulled out connections to ground (Black wire) and the index channel (Orange wire).  When the index fires, the voltage will go from zero to five volts.

More information on the encoders from Quantum Devices can be found at the link below-

http://www.servo2go.com/supplier.php?id=1057843244

For more information, please contact:

Editorial Contact:

Warren Osak
sales@servo2go.com
Toll Free Phone:  877-378-0240
Toll Free Fax:   877-378-0249
www.servo2go.com

 

Technical Article: Choosing a Rotary Encoder January 29, 2012

Posted by Servo2Go.com in Technical Support Information.
Tags:
add a comment

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 is dependent on the accuracy requirements of the application, whether it is position and/or velocity control. Before making an encoder decision, an engineer should examine this and all the major encoder properties that influence important motor performance.

Positioning accuracy
Positioning accuracy depends solely on the application requirements. Resolvers mostly have one signal period per revolution. Therefore, the position resolution is extremely limited, and the accuracy typically is in the range of ~ ±500” (Arc seconds), assuming interpolation in the drive electronics usually results in a total of 16,384 positions per revolution.

On the other hand, an inductive scanning system, as found in many rotary encoders, will provide significantly higher resolution, typically in the range of 32 signal periods per revolution, resulting in an accuracy of ~ ±280”. The interpolation in this case is internal to the encoder, resulting in 131,072 positions per revolution.

A good fit from the start will provide positive performance in the motor/drive system.

Optical rotary encoders are based on very fine graduations, commonly with 2,048 signal periods per revolution. Therefore, even much higher resolutions are possible with internal interpolation electronics. The output resolution here is 25 bits, 33,554,432 absolute positions per revolution, with accuracies in the range of ~ ±20”.

Speed stability
To ensure smooth drive performance, an encoder must provide a large number of measuring steps per revolution as the first piece of the puzzle. However, an engineer must also pay attention to the quality of the encoder signals. In order to achieve the high resolution required, the scanning signals must be interpolated. Inadequate scanning, contamination of the measuring standard, and insufficient signal conditioning can lead to the signals deviating from the ideal shape. During interpolation, errors then occur when the periodic cycle is within one signal period. Therefore, these position errors within one signal period are also referred to as “interpolation error.” With high-quality encoders, these errors are typically 1-2 percent of the signal period.

The interpolation error hurts the positioning accuracy and significantly degrades the speed stability and audible noise behavior of the drive. The speed controller calculates the nominal currents used to brake or accelerate the drive, depending on the error curve. At low feed rates, the feed drive lags the interpolation error. At increasing speeds, the frequency of the interpolation error also increases. Since the motor can only follow the error within the control bandwidth, its effect on the speed stability behavior decreases as the speed increases. However, the disturbances in the motor current continue to increase, which leads to disturbing noises in the drive at high control-loop gains.

Bandwidth
Bandwidth (relative to command response and control reliability) can be limited by the rigidity of the coupling between the motor shaft and encoder shaft, as well as by the natural frequency of the coupling. Encoders are qualified to operate within a specified acceleration range. Values typically range from 55-2,000Hz. However, if the application or poor mounting cause long-lasting resonant vibration, it will limit performance and possibly damage the encoder.

Reprint of Design News 1/4/2012 article by Tom Wyatt, HEIDENHAIN Corp.

Click on the link below for additional information on Servo2Go’s Rotary Encoders-

Servo2Go’s Rotary Encoder Product Family 

For more information, please contact:

EDITORIAL CONTACT:
Warren Osak
sales@servo2go.com 
Toll Free Phone:   877-378-0240
Toll Free Fax:       877-378-0249
www.servo2go.com

Quick Ship Industrial Encoders from Quantum Devices April 22, 2010

Posted by Servo2Go.com in News & Events.
Tags: , , , ,
add a comment

Servo2Go has just added hundreds of ‘Quick Ship’ Industrial Rotary and Modular Shaft Encoders to its broad range of feedback devices.

Quantum Devices' Encoder Family

Manufactured by Quantum Devices of Barneveld, WI  the new QPhase™ Family of Encoders feature high resolution, increased frequency response and superior reliability over temperature (0 to 120 degrees C).   

Incorporating Quantum’s patented sensor technology, all incremental and absolute encoders set a new standard in industrial ruggedness, and are backed by a 2 year factory warranty.

Hundreds of models are available to ship from Stock to 3 weeks.

More information on ‘Quick Ship’ Industrial Rotary and Modular Shaft Encoders can be viewed at-

http://servo2go.com/supplier.php?id=1057843244
For more information please contact:

sales@servo2go.com
Toll Free Phone:   877-378-0240
Toll Free Fax:       877-378-0249
www.servo2go.com