Product category:
Measurement systems including encoders
News Release from: Renishaw | Subject: Non-contact optical encoders
Edited by the Manufacturingtalk Editorial
Team on 11 July 2005
Meeting motion control feedback
requirements
Motion control feedback is now widely used in many diverse applications and requirements vary from high accuracy, low speed to low accuracy and high speed.
Motion control feedback is now widely used in many diverse applications Requirements vary from high accuracy, low speed to low accuracy and high speed
This article was originally published on Manufacturingtalk on 13 Jul 2005 at 8.00am (UK)
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Renishaw designs and manufactures a range of high performance non-contact optical encoders.
In rotary applications such as C-axis positioning and rotary tables, arc second accuracy performance is offered by Renishaw's RESR angle encoder.
In addition to Renishaw's high specification optical product range, a new range of magnetic rotary encoders has now been introduced.
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The RM and RE range incorporates compact, non-contact, magnetic sensing technology, which is suited to applications where optical angle encoders cannot be used due to demanding environmental conditions.
The resolution and accuracy of these magnetic rotary encoders make them suitable for totally different applications to Renishaw's existing RESR angle encoder.
The main benefit of Renishaw's magnetic rotary encoders, compared with other similar resolution/accuracy offerings available, is the robust non-contact design.
Additional benefits include low inertia of moving parts, reliable operation within external magnetic fields, variety of output formats, 5V and 24V power supply options, multiple package designs and competitive pricing, thanks to the simple design of the product.
Simple construction, innovative design and solid-state electronics, means that the RM and RE packaged range of magnetic encoders has many advantages over traditional optical rotary glass encoders.
These include: * Compact, non-contact, design.
* The ability to withstand high levels of shock, vibration and acceleration.
* Low inertia with only one small moving part.
* Zero-wear design.
* High immunity to dirt, dust and cutting fluids.
* Operation up to +125 deg C.
* Reliable position sensing up to 30,000 rev/min.
* Low unit cost and minimal cost of integration.
* Principle of operation - at the heart of every Renishaw magnetic rotary encoder are two core components - a small diametrically polarised magnet and a custom Hall sensor ASIC.
The custom ASIC detects the change in magnetic flux as the magnet rotates above it.
The encoder ASIC contains an array of Hall effect sensors arranged to generate a voltage when exposed to a magnetic flux field.
As the N and S poles pass over them, they experience changes in the flux field and generate changing voltages.
The sensors only respond to the component of the magnetic field that is perpendicular to the surface of the chip.
Through smart design, the ASIC is able to achieve cancellation of magnetic interference enabling it to operate in areas of high external magnetic fields and cope with imperfections in the shape of the flux field of the actuating magnet.
Signals coming out of the sensors are then interpolated by electronics to give the required resolution and required output format.
Output formats include absolute, incremental and analogue.
* Product range - designers who require the smallest possible encoder can incorporate the ASIC and magnet within their own designs, or purchase a modular solution.
Packaged versions are also available in non-contact (RM) or traditional bearing/shaft (RE) format, fully sealed to IP68.
The RM and RE encoders are available in either 22mm or 36mm diameter bodies with multiple industry standard mounting options.
Chips, modules and packaged products all offer easy integration with a range of industry standard output formats including absolute, incremental, analogue, linear voltage and linear current.
Resolutions are available from 7-bit (128 counts per revolution incremental) to 12-bit (4,096 counts per revolution incremental).
Supply voltage is either 5V or 24V depending on the encoder/output format.
* Applications - the rugged non-contact design of Renishaw's magnetic encoders makes them suitable for a diverse range of demanding applications - * Motors - for reliable high speed feedback control a number of different motor types require a robust low profile encoder solution.
* Pumps, actuators and valves - to provide reliable long term position information.
* Marine - for both instrumentation and feedback control in harsh environments.
* Medical - for reliable feedback in 'wash down' environments.
* Packaging and print - to provide reliable feedback information in industrial environments. Request a free brochure from Renishaw ...
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