Sensing technology takes the lead: Drives & Controls 2012

Written by: Paul Fanning | Published:
Drives and Controls 2012: Sensing technology takes the lead

A number of novel developments in sensors, test and measurement were well represented at the recent Drives & Controls exhibition in Birmingham.

Among these were offerings from Leuze, including its ODSL 9 series of optical distance sensors. These sensors are offer a large measurement range from 50 to 650mm – with high accuracy at the same time. They offer resolutions starting at 0.1mm at a repeatability of 0.5% from the anticipated value. The measurement rate of 500Hz (in speed mode up to 700Hz) makes the ODSL 9 distance sensors the ideal solution for moving applications.
This speed can also be used to filter measurement values as well as for static pre-processing. The devices operate largely independent of object characteristics, meaning they are insensitive to gloss, surface and bright ambient light.

Also from Leuze comes what the company claims is the world's smallest contrast sensor. The KRT 3B series distinguish between grayscale values, enabling them to detect minimal contrasts. As a result, a check can be performed for the presence of text, imprints or marks.

The KRT 3B's stablemate, the KRT 20B brings this performance and technology in a larger housing. The KRT 20B is manufactured in an extremely robust plastic housing using a special manufacturing process. Mounting points made of stainless steel ensure a secure connection. Four optical systems connect with an outlet on the front and upper-front face, each with lengthwise or horizontal orientation of the light spot to ensure flexibility in mounting. The KRT 20B is available in two power classes, standard and advanced, with switching frequencies of 6 and 10kHz.

Sick UK also showed a distance sensor, albeit a laser distance measurement sensor. The DL100 Hi is designed to achieve high levels of accuracy over greater distances for positioning and control in fast-moving environments.

With the DL100Hi, Sick has developed significantly improved control loop technology to achieve faster and more accurate position feedback. The sensors' data output supports applications with acceleration values up to 15m/s2. As a result, for example, storage and retrieval systems can become more efficient - achieving shorter run times and more runs per hour.

The DL100Hi offers the choice of three measuring ranges to suit customers' applications (0.15 to 100mm, 0.15 to 200mm and 0.15 to 300mm) with a positional accuracy of ±2mm and repeatability of ±0.5mm.

The DL100 Hi is the first sensor to utilise a new modular platform for Sick distance sensors, offering flexibility and easy interchangeability within a common mechanical and electrical design. A wide variety of feedback interfaces are supported including SSI, RS422 and Profibus.

Outlining the benefits of this, Sick product specialist Darren Pratt said: "As a result of this improved performance, operators can achieve significant improvements in operating efficiency. At the same time, the sensors' robustness and reliability reduce the risk of downtime and offer longer periods between replacement."

A fully fail-safe inductive sensor was launched by ifm electronic at the exhibition. The GG851S fail-safe inductive sensor simplifies some of the safety-related applications for such sensors.

A safe-state is given when the target is not present, i.e. outside the 10mm enable zone, in the area known as the safe switch-off zone. If a metal object is in the enable zone, the outputs are switched on. It also has a wider operating voltage than earlier versions, allowing operation down to 12V DC.

The operating principle can be illustrated using the example of a gantry crane.

With a normally open version, when the fail-safe sensor monitors the position of the crane on the gantry the sensor would need to be damped along the whole travel in order to maintain the safe function with the sensor only undamped at the stop positions.

This new version allows mounting of only one target each at the beginning and the end of the crane track, which saves material and mounting cost.

The GG851S sensor has two OSSD outputs for connection to a safety relay or PLC. The diagnosis of the different operating states is made using LEDs. No special target is required and the GG851S is fully flush-mountable.
The fail-safe sensor is certified to ISO 13849-1 PL d, IEC 61508 SIL 2 and IEC 62061 SIL cl2.

Renishaw was displaying its Resolute true absolute optical encoder, which is capable of 27-bit resolution at 36,000rpm. With high accuracy scales, outstanding motion control, excellent dirt immunity and wide set-up tolerances, Resolute is claimed to outperform other non-contact absolute encoders. The fine-pitch system delivers a market-leading resolution of just 1nm at up to 100m/s, for both linear and angle encoding applications. It is available with a range of high-speed serial communications protocols.

Also on show was the Resolute ETR (Extended Temperature Range) encoder that brings all the benefits of the Resolute range including fine pitch angle encoder to harsh, low-temperature applications. With operation guaranteed down to -40°C in non-condensing environments, Resolute ETR is perfectly suited for use in demanding applications such as telescopes, scientific research, military equipment or aerospace platforms.

For embedded motion control applications, Renishaw's RoLin offers a component level non-contact magnetic encoder. The system consists of a readhead and magnetic scale or ring, with electronics inside the readhead allowing high interpolation factors up to 13-bits and integrated fault monitoring. A wide range of resolutions is available from 0.244µm to 125µm, with speeds up to 40m/s (dependent on chosen resolution). Radial or axial reading of the ring is possible. This product is intended for high-volume applications in sectors where miniature axes are required.

Additionally Renishaw's TONiC incremental optical encoders with a range of metal scales are claimed to provide the performance of fine-pitch glass scales, but in a simple-to-install package.


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