A major upgrade of one of Finland's leading theatres incorporates a
completely new stage control system, which relies on the advanced control
functionality of some 60 ac drives
The Theatre at Oulu, Finland - certainly one of the most northerly in the
world - runs between three and six different shows a week and hosts ten
premiers a year. A recent extensive refurbishment included replacement of
all of the electrical distribution system, motors, drives and control
system to improve availability - decreasing downtime between performances
and increasing the time available for on-stage performances.
With the high utilisation of this theatre, a high level of automation is
required to ensure a fast turn-around between the performances, says
Vesa Leikas, president of Mechatronics Oy, the company responsible for
the design, manufacture and installation of Oulu's new theatre control
system. The daunting combination of heavy loads, high speed and high
precision movements, and the need for utmost reliability of this control
system called for drives to match, and for Mechatronics that meant
Control Techniques' Unidrive SP.
Drives from 1.5kW to 22kW control two lighting and 27 scenery (batten)
hoists, 15 moveable point hoists, three positioning motors for the
lighting bridges, two hoists for speakers and video screens, curtain
tracks and five stage lifts within the stage turntable. The whole system
is computer controlled, with two above stage operator control points
connected by Ethernet and wireless links to the main server for laptop
and palmtop control for specific functions that may require close quarter
control from the wings.
Two MC400 controllers, each capable of controlling 100 axes, provide
mutual back-up and real time control, interfacing between the computer
network and the drives, each of which operates in vector mode with
each hoist. The MC400 controllers receive the positional information from
each absolute encoder and therefore knows the status of each movement.
The drives cubicles also contain axis connection modules for each drive.
These modules, which also receive encoder and limit switch signals as
well as providing speed and position control signals to the drives, are
connected to the MC400 controllers via optical fibre for ultra-fast
exchange of control data. Loads of typically 500kg or more can be
positioned anywhere on stage in increments of 1mm, very quickly and
silently.
For this we need a high dynamic performance, says Mr Leikas, and with
gearings typically in the region of 1:2,000, we achieve very high
accuracy. We can run shows completely automatically, including time codes
across the whole system linked to soundtrack and lighting cues,
completely manually, or a mixture of both.
The Unidrive SPs give us much flexibility as well as precision. We use
their on-board processing capabilities for a variety of additional
functions, including the internal PLC. And, where we have a large number
of drives to programme identically, we have found the SmartCard cloning
to be particularly useful and time-saving during set-up.
The computer control system for the Oulu Theatre runs sophisticated stage
design and control programs from Mechatronics - VisualStage Online and
StageManager - that give three dimensional views of the stage, with zoom,
rotation, and different viewpoints to show set design effects. It is
possible to see the set from any viewpoint of actors and from any point
in the auditorium. This dramatically cuts the time required for the
design of the stage set-up and translates into position and movement
control for each of the hoists and lifts.
Unidrive SP is an advanced 'solutions platform' ac drive, configurable
into five operating modes, connecting to most industry standard networks
and accepting 14 position feedback protocols. With a range of plug-in
module options, its on-board