Assistive Actuation of Brass Instrument Valves
Raymond Gallagher, Daniel Isaac, Zachary Kaltz, Matthew Ryerkerk
III - Modeling
I - Introduction
Valve Actuation System:
Reverend Richard Moe was born with spinal
muscular atrophy (SMA), a progressive &
degenerative muscle condition. With the recent loss
of the strength in his fingers, he was unable to
effectively operate the valves on his tuba. The scope
of this project was to develop an assistive valve
actuation system that would allow Mr. Moe to
continue to play his instrument with minimal strength.
Additionally, a support system was necessary; this
would bear the weight of the tuba while also raising
the height of the mouthpiece to promote beneficial
posture.
It was required that the solenoids have a holding force of at least 1.2 lbs (5.3
N), a maximum response time of 0.3 seconds, and a stroke distance of 1inch
(2.54 cm). Further, a 100% duty cycle was required. The final design was
determined to have a response time of approximately 0.2 seconds for each of
the valves. It was calculated that a .625 Amp current at 24 Volts was needed to
operate the device.
Spacing of the solenoids was an important factor in the modeling of the device.
The valves on the tuba were 0.5 inches apart.
2.56 inches
IV – Future Considerations
Additional work optimizing the size and weight of the device is
needed in order obtain the most robust product. Additionally, the
performance of the device can be optimized by developing a
custom made solenoid design specifically for the required force
and stroke distance required. The valve actuation system
developed should not be restricted use only with the tuba.
Additional work is necessary in order to modify the device so as
to make it compatible with an instrument being played.
0.75 inches
II - Design
Bolts
Valve Actuation System:
1
Acrylic
1 inch
2
3
-Actuators
Linear solenoids provided
the force and displacement
to operate the instrument
valves.
Figure 1. Linear solenoids
(R24X30 Magnet-Schultz)
Figure 5 (a). Valve spacing as
seen on actual instrument
Valves
Valve Open
-Mounting
Acrylic plates with foam are
bolted to each other to hold
the solenoids above the
valves.
Pushing force = 1.2 lbs
Solenoids
1 inch
Valves
Figure 2. Three solenoids were
mounted to acrylic plates.
Valves
Figure 5 (b). Valve in open and
closed positions with a 1 inch
stroke distance
-Control Box
Low-resistance switches
independently controlled the
solenoids. Velcro on the
control box and mounting
allowed adjustable
positioning for user comfort.
Springs
1
inch
Restoring force of spring
Figure 3. The mounted actuation
system has an adjustable control box.
Instrument Support System:
A contoured cushion was chosen as the
support system. Rubber grip fabric on the
bottom prevents the instrument from sliding off
the seat. The straps attach the cushion to the
tuba and can compress the cushion for an
adjustable height.
Figure 4. The support cushion
attaches to the bottom of the tuba.
Valve Closed
Figure 4. The solenoids (D=1.5
inches) were modeled in Unigraphics
as per the dimensions specified by
the manufacturer
Instrument Support System:
The instrument support pad was
modeled to fit in between the legs of
Mr. Moe and rest on the seat of the
wheelchair. A cutout in the center of
the pad was made in and straps were
added to ensure secure attachment to
the tuba.
Acknowledgements
The authors would like to thank the following people for
their dedication, generosity, and support which greatly
contributed to the success of this project.
•Chris Roush – Marshall Music Co.
•Greg Ritchey – Magnet-Schultz of America
•Rich Yarch – MSU Upholstery Shop
•Dr. Robert Hubbard
•Mr. Timothy Hinds – Project Advisor