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| Harmonica
Servo Drive Application |
| Using Elmo’s
Harmonica Digital Servo Drive,
TekCel of Hopkinton, Massachusettes designed and built
a very compact material handling system for test tubes
and plates. The Harmonica was designed into an enclosure
that operates at a study -20° C. |
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TekCel’s Tube Management
Platform
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| Modern medical testing laboratories must automate their
test procedures in order to lower costs and stay competitive.
Drug and biotech companies do the same to speed up their
product development cycles. |
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| Automated material
handling and storage systems, for medical laboratories, are
now available to do just that. They contain trays for storing
chemicals and test materials in inert, temperature-controlled
environments, and handling systems for moving the trays to test
areas where materials can be mixed automatically. The resulting
mix is placed in test tubes or plates and are then either stored
in the same system or transfered out of it. |
| At the heart of
such systems is (1) a database that knows where the materials
are stored and keeps a history of each individual test tube
or plate, and (2) a computer that controls all activities and
movements. |
| TekCel’s approach
is to build individual storage, transfer, and mixing modules
that can be assembled and disassembled as easily as building
blocks. Each storage module contains its own database so that
the overall system, when assembled, knows what’s inside
each and every tube or plate within the system. |
| TekCel’s Tube Management
System is a fully automated, integrated and environmentally
controlled platform for flexible format tube storage, retrieval
and processing. The system provides unparalleled flexibility
in tube format, storage capacity and throughput. |
| At the core of the Tube Management
System is the TubeStore module. Each self-contained module is
equipped to pick and compile individual 2-D barcoded tubes,
or 96-tube racks, within an inert, temperature controlled environment.
The modular design of the TubeStore allows the capacity of the
Tube Management System to be expanded by combining multiple
TubeStore modules. |
| For more information about
TekCel’s line of products, see www.tekcel.com. |
| Distribute motor
controls in a limited amount of space and in a low temperature
environment. |
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tight space limitations |
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provide power for
linear and rotary motors |
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control by self-contained
programs (position mode) |
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connectivity via
CANopen |
| TekCel
and Elmo’s Solution |
| TekCel adopted a Windows PC-based
control architecture, which offers many advantages, but lacks
real-time control. Because Elmo’s Harmonica can execute
an internal script, it can coordinate servo motors, sensors
and pneumatics into an autonomous sequence of events. Multiple
scripts can be retained in on-board fl ash memory and, after
initiation, no further support is required from the PC. |
| Previously, sensors
and servo positions were polled by the PC and servo/output commands
issued. The embedded script eliminated delays due to latency
and improved throughput by approximately 30%. In this application
multiple Harmonica’s are configured as a “group”
and their application-specific scripts initiated via a single
PC command, enabling multiple servos to work together on real-time
tasks. |
| Previously,
TekCel utilized a proprietary distributed servo controller that
utilized a multi-drop RS485 network. The Harmonica provided
a similar package size with more current capability, more robust
CAN communication, wide operating temperature range and similar
cable management. Expanded I/O and advanced servo tuning were
other factors that made the switch to the Harmonica the logical
choice. |
| The Harmonica digital sevo
drive was designed into two major components: the storage system
and the plate management unit. |
| Harmonica
Digital Servo Drive |
| The Harmonica is a fully
digital servo drive that delivers up to 1 KW of continuous
power (and 2 KW of peak power) for DC brush, brushless
and linear motors. It can operate in current, velocity
or position modes and functions with a wide variety of
feedback options including Incremental Encoders, Resolvers,
Interpolated Analog (Sine/ Cosine) Encoders, tachometers
and potentiometers. The tiny drive packs one horsepower
into a 150 gram (5.3 oz) package. It features sinusoidal
vector control, trapezoidal vector control, trapezoidal
six-step and DC commutation methods. The Harmonica has
an auxiliary feedback port for ECAM, Follower, Dual Loop
and Pulse-and-Direction applications. Digital and analog
ports are also available. Integrated into the drive is
highly efficient power switching technology aligned with
Elmo’s especially fast implementation of CANopen
networking (DS-301/DS-402) protocol. One CANopen port
is installed along with one RS-232 serial port for communications.
The Harmonica is fully programmable with Elmo Motion Control’s
programming language (32 KB of memory is available for
storing programs). Using Elmo’s Composer setup tool,
Harmonica users can perform drive setup, configuration,
tuning, analysis and drive programming quickly and easily. |
| For more information: Harmonica Servo Drive. |
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Harmonica Digital
Servo Drive
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