This Week in Motion – February 7, 2011

Senior Editor Miles Budimir highlights some of the week’s new motion control products with a focus this week on encoders. Specifically, a 27-bit encoder from Renishaw, an inductive rotary encoder from Heidenhain, and magnetostrictive sensors from MTS Systems.

Encoder delivers higher resolution for better speed control

“If you want to control the speed of a particular move,” noted Kevin Kaufenberg, product manager for HEIDENHAIN Corporation’s semiconductor, metrology, and medical markets, “the more counts an encoder can output per given period of time, the better the speed control will be. So having a very fine resolution from the encoder provides more counts that the controls can use to manage speed.”

The company recently introduced the LIC 4000, a scale encoder with a resolution of 1 nm that is geared towards equipment for the medical markets, general motion, and semiconductor industries. Continued Kaufenberg, “the general rule in the motion industry is that if you want to position to 1 mm, then you should have ten times better the resolution, or 100 nm in that case. Someone could use the LIC 4000 encoder system to position to 10 nm.
Along with the high resolution, the encoder features absolute position measurement. The multi-substrate scale tape linear encoder reads current position immediately upon switch-on, eliminating the need for reference runs. Absolute encoders are well suited for use on direct drives. Together with the current position, the commutation offset is known immediately upon switch-on, so the motor can be provided with power and held in the control loop. Critical operating states, such as switching on a vertical axis with direct drive or retraction after an emergency stop, are controlled safely.

These encoders are insensitive to contamination, including electromagnetic interference. They use the Endat interface, which constantly checks itself for the proper data transmission. If encoders are mounted next to motors, electromagnetic noise can interfere with encoder signals. But with HEIDENHAIN cables and the Endat interface, the cyclic checks prevent miscounts in the encoder interface, which helps ensure safe motion.

The dimensions of the LIC 4000 match those of the company’s LIDA 400 incremental linear encoder for an easy retrofit. Thus, today’s motion control equipment can use absolute measurement technology by exchanging the encoders. Only the subsequent electronics must be adapted correspondingly.

HEIDENHAIN Corp.
www.heidenhain.com

HEIDENHAIN’s 1000 Series Rotary Encoders

SCHAUMBURG, IL - Opening up the market for innovations in the automation, medicine and electronics equipment industries, HEIDENHAIN Corporation presents a new generation of rotary encoders with IP 64 protection, absolute position-value formation and functional safety, all within a 35 mm diameter housing size. These small rotary encoders are known as HEIDENHAIN’s 1000 Series and designed to be especially useful as single-encoder measurement feedback systems in safety-oriented applications.

HEIDENHAIN’s safety-oriented position encoders with functional safety provide two independently formed position values via a serial EnDat interface. They are certified according to the EN ISO 13849, EN 61508 and EN 954-1 standard for performance level d, safety integrity level 2 and category 3, respectively. The EnDat 2.2 version of these new absolute rotary encoders with serial data transfer offers a singleturn resolution of 23 bits, and a multiturn resolution of 12 bits. The supply voltage range is from 3.6 V to 14 V.

Eight new rotary encoders round out HEIDENHAIN’s 1000 Series including:

–ECN 1013, ECN 1025, EQN 1025, EQN 1035, ROC 1013, ROC 1025, ROQ 1025 and ROQ 1035.

HEIDENHAIN CORPORATION
www.heidenhain.com

ControlLogix Interface Communicates with EnDat Sensors

Terryville, CT – A direct interface to EnDat position encoders is now available for the 1756 ControlLogix PLC. The AMCI 7272 module is a digital, bidirectional interface for EnDat encoders, with features including latch inputs, onboard diagnostics, and read/write access. Utilizing Rockwell Automation licensed technology, the 7272 EnDat Interface PLC module is 100% compatible with the 1756 ControlLogix PLC.

The 7272 EnDat interface module directly interfaces with all Heidenhain EnDat 2.1 rotary encoders, high accuracy angle encoders, and linear scales. The module is digital, two-channel, and bidirectional; enabling it to transmit position values as well as read and update information stored in the encoder, or save new information. For high system reliability, sensor data such as application-specific parameters, compensation tables, error detection, and diagnostic capabilities are made available with this module. Several other features come standard.

EnDat position sensors are bidirectional, and thanks to the serial transmission method supported by AMCI’s 7272 module, only four signal lines are required. They are also self-commissioning, reporting all the encoder’s properties to the controller at power up. OEMs can download application specific data to the encoder’s freely definable memory area. By using the AMCI EnDat interface module, use of these valuable functions is made available through the ControlLogix PLC.

AMCI’s EnDat interface module paired with a Heidenhain EnDat encoder provides a feedback solution for all applications in motion control. Examples of applications that benefit from this pairing include machine tool, printing, and robotics.

Advanced Micro Controls Inc.
www.amci.com

Inductive Rotary Encoders for Resolver Systems

SCHAUMBURG, IL – The inductive rotary encoders of the HEIDENHAIN ExI 1100 series are now available in versions whose mating dimensions are the same as those of common types of resolvers. Depending on the respective applications and accuracy requirements, inductive or optical absolute encoders are now possible as high resolution alternatives to resolvers. These encoders are easy to mount and inexpensive, and are destined for applications that require a high degree of reliability and durability.

Furthermore, the HEIDENHAIN ExI 1100 rotary encoders with EnDat 2.1 interface feature an improved inductive scanning method, with which the singleturn resolution was increased to 18 bits (262,144 position values per revolution). This results in a higher control quality of the drive.

Servo drives with inductive rotary encoders enjoy advantages over those using resolvers in terms of positioning accuracy, speed stability and control dynamics. This is made possible by the greater control bandwidth and a significantly higher number of signal periods for the formation of the singleturn position value. The position value is produced by electronics already integrated in the encoder, and is transferred as purely digital information to the higher-level electronics over the fast bidirectional EnDat interface. As an option, the information can be transferred as an analog signal. An integrated readable and writable EEPROM makes user parameters available in the subsequent electronics at all times, enabling the encoder and its environment to self-configure over the synchronous serial interface.

The encoder’s real multiturn capability frees the system from the need to be “homed” after power interruptions or switch-on. Conventional battery-supported systems requiring regular maintenance are no longer needed. Alarm and diagnostic functions ensure high system availability rates.

www.heidenhain.com

RENCO R28i Modular Encoder

GOLETA, CA – The new R28i Modular Encoder is perfectly suited for size 11 step motor applications, providing state-of-the-art performance in a 28mm package. The innovative design is self-aligning and self-gapping, and requires no special tooling for installation. Our custom OPTO-ASIC provides a wide range of available resolutions, and sets the standard for resolution and performance.

Now distributed and available through parent company HEIDENHAIN Corporation, this RENCO R28i can also accommodate motor shafts up to 7mm making it suitable for brush motor, step motor, and lead-screw applications. To provide a robust mounting, the motor can utilize the existing motor assembly screws, or dedicated mounting points for durability and reliability.

www.renco.com

HEIDENHAIN Increases CNC Accuracy with KinematicsOpt

SCHAUMBURG, IL – HEIDENHAIN Corporation now offers a new option to its iTNC 530 contouring control, now making possible the automatic measurement of a machine rotary axis. Called KinematicsOpt, this new software option, coupled with a mounted HEIDENHAIN touch probe into the CNC machine spindle, increases the accuracy of this already high functioning control. The iTNC 530 can control up to 13 axes and a spindle.

The introduction of KinematicsOpt is the answer to CNC accuracy requirements becoming increasingly stringent, particularly in the area of 5-axis machining. With KinematicsOpt, it does not matter whether the individual axis being measured is a rotary table, tilting table or swivel head. The measurement process is the same.

The procedure begins after having defined the measurement resolution and the area of each rotary axis that is to be measured. The operator then initiates probing of a calibration ball fixed at any position on the machine table. From the measured values, the iTNC 530 calculates the statistical tilting accuracy, with the KinematicsOpt software minimizing the spatial error arising from the tilting movements.

At the end of the measurement cycle, the machine geometry is saved in the respective machine constants of the kinematic table. A comprehensive log file is also saved, recording the actual measured cycles and the optimized dispersion (measure of the statistical tilting accuracy) as well as actual compensation values.

www.heidenhain.com