| Applications & Engineering |
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Market: Foundry/steel making equipment
Product: AG626 multi-turn absolute
A company which produces control systems for applications within the steel mill and foundry industries decided to standardize on the rugged AG626 multi-turn absolute encoder for their feedback device. Many unique and demanding sub-applications exist within the general steel and foundry market; including casters and rolling mills. All new control systems for these applications will use the AG626, a magnetic encoder, which was chosen primarily because of itís exceptional resistance to the extreme environmental conditions found in these mills. These specifications include: -20 to +85 degree C temperature range, IP65 environmental protection rating, and high shock resistance of 100g/6ms. Other reasons the AG626 was selected include; the multi-turn resolution capability up to as high as 24 bit ( 4096 x 4096 ) with a correspondingly low market price, and the advantages of the SSI interface. These advantages include; only six wires needed for fast data transmission, and differential data transmission of gray code data in a synchronous format to ensure reliable data transmission. The benefits of SSI transmission to the customer are greatly increased reliability and greatly reduced transmission line costs. The AG626 will be used to provide position and velocity feedback in these applications.
The majority of steel mill control systems use VME bus control systems because of their speed in processing data from various I/O devices. This particular company chose to work with a third party company to design and supply a VME serial interface card especially for the SSI protocol. This plug in board will be able to handle interfacing 4-6 encoders, allowing an inexpensive and clean way to interface to the AG626.
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Automatic Storage and Retrieval Systems
Absolute data is required to establish vehicle position on the track and to determine height for accurate positioning of palletized or container goods. Multi-turn absolute encoders provide continuous position information and do not lose position in a power loss. This is critical in preventing crashes and eliminates the need to zero or initialize the machine. The ability to transmit data over a long distance is another important feature. |
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Robotics
An absolute encoder is advantageous in robotics, due to the high gear ratios required by the servo motor in providing motion to the robot arm. An absolute encoder is better suited than an incremental device for two other important reasons: better immunity to electrical noise and the ability to provide a true position without having to be reset to a home reference point. A loss of position could result in a collision of equipment or injury to a bystander. |
Valve Controls
Valve position control is well suited for absolute encoders. Whether single or multi-turn, the advantages of an absolute encoder are considerable. Typically, when a valve is powered, it is essential to know the position immediately without going through an initialization routine. Only an absolute encoder can provide this. Other features, such as the ability to transmit data over long distance for signal integrity and the need for absolute position for safety reasons, are also important. |
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