[0001] The object of the invention is a mechatronic action for a pipe organ and a method
for controlling the power supply to a voice coil motor (VCM) in a mechatronic action
for a pipe organ in which a VCM is used.
[0002] In a pipe organ, sound is produced by the flow of air through the pipe (1). This
flow is regulated by a valve in which the moving element is a pallet (3). The pallet,
together with the return spring (2), is located in the windchest (4), where there
is increased air pressure generated by the pneumatic supply system (usually a blower
with bellows). The control element of the valve is the key (6) and the system that
transmits the control signal from the key to the pallet is the action (5). The most
common types of actuator are mechanical (tracker), pneumatic, and electric. Mechanical
action is a system of mechanical connections using linkages, levers and rollers. Pneumatic
action uses a system of compressed air to transmit the signal from the key to the
pallet. Electric action uses an electromagnetic actuator (usually an electromagnet)
to create the movement of the pallet, which is activated by a switch (usually an electrical
contact system) attached to the key. Mechanical and electric action are currently
the most commonly used in organ building. Mechanical action allows full control over
the dynamics of sound generation (the speed at which the pallet opens and closes),
with the limitation that the playing table (keyboard) must be placed very close to
the instrument. Electric action allows the keyboard to be moved away from the instrument,
but does not offer control over the dynamics of the sound produced by the organ. The
system that moves the valve pallet (electromagnet) works in two modes: either it is
off - the key is closed - or it is on and the key is open. The speed at which the
pallet opens is determined and limited by the dynamics of the electromagnet.
[0003] A method of controlling an electric action is known from the description of the invention
PL174978, in which the velocity of the key press (articulation) is a control signal from a
dynamic keyboard and is processed by a fuzzy logic that controls an electromagnetic
actuator (electromagnet) that opens the valve of the pipe.
[0005] From the description of the invention of the
US patent 8,198,521, 2012, it is known that the pipe organ drive systems - electromagnets - are proportionally
controlled to achieve any pallet opening. A mechatronic action is known (T K

dzio

ka, S Kowalski, T Mońko, "Pipe organ evolution. From mechanical to mechatronic subsystems",
Journal of Engineering, Energy and Informatics 1/2021 (1), 29-42), where the actuator
moving the pallet is a stepper motor.
[0007] The aim of the invention is to develop such a mechatronic action, which will have
the characteristics of mechanical action - the ability to fully control the dynamics
of sound generation, i.e. to control the speed of opening and closing of the pallet,
and, as in the case of electric action, to allow the playing table to be moved away
from the instrument.
[0008] The essence of the invention is a mechatronic action for a pipe organ, characterised
in that, for one note - one key (12) of the keyboard - it consists of a VCM (9) connected
by a linkage (10) to the pallet (8) of the pipe valve (7) or pipes in the case of
a multi-voice organ, a key displacement sensor (11) and a microprocessor system (13)
which, on the basis of the signal from the key displacement sensor (11), controls
the power supply to the VCM (9).
[0009] The essence of the invention is also a method of controlling the power supply of
the VCM in the mechatronic action of a pipe organ, consisting in the fact that the
microprocessor system, on the basis of the signal from the key displacement sensor,
which is information about the key displacement, determines the value of the power
supply of the VCM motor according to the formula:

where: y is the VCM supply value (voltage or PWM signal) expressed as a percentage
of the maximum supply value, x is the key displacement value measured by the key displacement
sensor and expressed as a percentage of the maximum key displacement value,
k1 is a signal gain constant determined during control system tuning,
MIN is the VCM supply value determined by measurements and read from the pallet opening
curve, corresponding in the pallet opening process to the maximum VCM supply value
for a closed pallet or in the pallet closing process to the maximum VCM supply value
for a closed pallet,
MAX is the VCM supply value measured and read from the pallet opening curve, corresponding
in the pallet opening process to the maximum VCM supply value for a closed pallet,
corresponding in the pallet opening process to the minimum VCM supply value for a
fully open pallet or in the pallet closing process to the minimum VCM supply value
for a fully open pallet, the change in the MIN and MAX values for changes in the pallet
opening and closing process taking place after the key displacement equal to or greater
than 75% of the maximum key displacement and after the time corresponding to the pallet
opening at 50% of full opening determined from the waveform of the pallet opening
at the step forcing of the VCM supply and counted from the moment of the start of
the pallet opening process.
[0010] The invention is visualised in the drawing in which Fig. 1 shows the sound generation
system in a pipe organ, Fig. 2 the mechatronic action, Fig. 3 curves of the pallet
opening versus the VCM supply, Fig. 4 the waveform of the opening of the pallet as
a result of the stepping of the VCM supply.
Example.
[0011] Thanks to its design and the way in which the VCM supply is controlled, the mechatronic
action makes it possible to fully control the dynamics of sound generation, i.e.,
the pipe valve pallets open in accordance with the keys being moved - pressed by the
organist.
[0012] The object of the invention is a mechatronic action device used in a pipe organ,
consisting of (for one sound - one key (12) of the keyboard): a VCM (9) connected
by a linkage (10) to a pallet (8) of a pipe valve (7) or pipes in the case of a multi-voice
organ, a key displacement sensor (11), and a microprocessor system (13) which, on
the basis of the signal from the key displacement sensor (11), controls the power
supply to the VCM (9).
[0013] The control of the VCM feed is based on parameters determined by measurement: the
pallet opening and closing curve as a function of the VCM supply moving pallet (Fig.
3) and the dynamic pallet opening curve as a result of the VCM supply step (Fig. 4).
[0014] In the process of opening the pallet, there is a limit - a maximum - value
A of the VCM supply at which the pallet remains closed - where the supply value is
the voltage or PWM signal expressed as a percentage of the maximum supply value. Increasing
the supply value above the
A value triggers the pallet opening process - the VCM connected to the pallet by a
linkage starts to move the pallet. When the VCM supply exceeds the
A value, the pallet opening (
K) is rapidly increased - the pallet falls. This effect is due to the fact that as
long as the pallet is closed, the air pressure in the winch presses against the pallet.
To open the pallet, the actuator must apply a force greater than the force generated
by the return spring and the force generated by the air pressure in the winch. When
the pallet is opened, even slightly, a stream of air begins to flow into the pipe.
The air pressure on both sides of the pallet is equalised and the force of the air
pressing on the pallet disappears. The force produced by the actuator then causes
the pallet to jump (fall). The same phenomenon is experienced by the organist in the
case of a mechanical action such as a key pluck (German: Druckpunkt). As the VCM supply
continues to increase, the pallet opens further and further until it opens completely,
which occurs at the
B value of the VCM supply. Further increases in VCM supply will not change the pallet
opening.
[0015] The pallet closing process follows the earlier pallet opening and begins when the
VCM motor supply drops below
H, the minimum VCM supply at which the pallet remains fully open. As the VCM supply
continues to decrease, the pallet will open less and less until the VCM supply reaches
G, which is the maximum VCM supply for a closed pallet during the pallet closing process.
[0016] The dynamic waveform of the pallet opening when the VCM is stepped makes it possible
to determine the time ΔT required for the pallet to open halfway, which corresponds
to the pallet dropping during normal pallet opening.
[0017] The power supply control of VCM in mechatronic action is based on the principle:

Where:
- y-
- value of the VCM supply expressed as a percentage of the maximum supply value,
- x-
- the key displacement, which is measured by the key displacement sensor and is expressed
as a percentage of the maximum key displacement value,
- k1 -
- signal gain constant determined during control system tuning,
- MIN -
- value of the VCM supply corresponding, in the pallet opening process, to the maximum
value of the VCM supply for a closed pallet (A) or, in the pallet closing process, to the maximum value of the VCM supply for a
closed pallet (G),
- MAX -
- value of the VCM supply corresponding to the process of opening the pallet, to the
minimum value of the VCM supply for a fully open pallet (B) or, in the process of closing the pallet, to the minimum value of the VCM supply
for a fully open pallet (H) The change in the MIN and MAX values for the changes in the pallet opening and closing processes occurs after a
key displacement equal to or greater than 75% of the maximum key displacement and
after a ΔT time corresponding to the pallet opening at 50% of the full opening for
the dynamic pallet opening when the VCM supply is stepped, and calculated from the
moment of the pallet opening process.
Markings on the drawing:
[0018]
- 1 - pipe,
- 2 - return spring,
- 3 - valve pallet,
- 4 - windlass
- 5 - linkage,
- 6 - key,
- 7 - pipe,
- 8 - valve pallet,
- 9 - VCM,
- 10 - link,
- 11 - key displacement sensor,
- 12- key,
- 13 - microprocessor.
1. A mechatronic action for a pipe organ, characterised in that, for one tone - one key (12) of the keyboard - it consists of a VCM (9) connected
by a linkage (10) to a pallet (8) of the valve of the pipe (7) or pipes in the case
of a multi-voice organ, a key displacement sensor (11) and a microprocessor system
(13) which, on the basis of the signal from the key displacement sensor (11), controls
the power supply to the VCM (9).
2. Method of controlling the power supply of the VCM in the mechatronic action of a pipe
organ,
characterised by the fact that the microprocessor system, on the basis of the signal from the key
displacement sensor, which is information about the key displacement, determines the
power supply value of the VCM motor according to the formula:

where: y is the value of the VCM supply (voltage or PWM signal) expressed as a percentage
of the maximum supply value, x is the key displacement value measured by the key displacement
sensor and expressed as a percentage of the maximum key displacement value,
k1 means a signal amplification constant determined during the control system tuning,
MIN means the VCM supply value determined by measurements and read from the pallet opening
curve, corresponding in the pallet opening process to the maximum VCM supply value
for a closed pallet or in the pallet closing process to the maximum VCM supply value
for a closed pallet,
MAX means the VCM supply value measured and read from the pallet opening curve, corresponding
in the pallet opening process to the minimum VCM supply value for a fully open pallet
or in the pallet closing process to the minimum VCM supply value for a fully open
pallet, whereby the change of
MIN and
MAX values for changes in the process of opening and closing the pallet occurs after the
key displacement equal to or greater than 75% of the maximum key displacement and
after the time corresponding to the pallet opening at 50% of the full opening determined
from the waveform of the pallet opening at the step forcing of the VCM supply, and
counted from the moment of the start of the pallet opening process.