LT360 Precision Turntable
User Manual
LT360 Precision Turntable
User Manual
44
0 - Impulse
The Impulse function provides the fastest rise time from zero to constant
velocity. However it also greatly reduces the maximum load which the
LT360 can rotate, due to its higher acceleration. The acceleration of this
function is about 10X that of the others.
The Impulse function is useful for light loads where a fast response time is
desired. However for most typical LT360 applications where a heavy load is
being rotated, this function is probably the least desireable. Using one of the
other softer acceleration functions is preferrable for heavy loads.
1 - Flat
The Flat function provides constant acceleration until the platter reaches the
constant velocity rotational rate, as set by the RPM value. This is probably a
good general purpose profile for most typical applications. The load is
accelerated under a constant value which provides maximum torque han-
dling and relatively little load disturbance.
2 - Ramp
The Ramp function provides a more gradual acceleration profile, beginning
at zero, ramping to a maximum, then decreasing to zero again as the
constant velocity speed is reached. This acceleration profile is based on a
parabolic velocity function.
45
3 - SIN2
The Sin2 function provides a more gradual acceleration profile, beginning at
zero, increasing to a maximum, then decreasing to zero again as the
constant velocity speed is reached. This acceleration profile is based on a
Sin
2
acceleration function.
4 - SIN3
The Sin3 function provides a more gradual acceleration profile, beginning at
zero, increasing to a maximum, then decreasing to zero again as the
constant velocity speed is reached. This acceleration profile is based on a
Sin
3
acceleration function.
In theory each increasing index of the acceleration functions provides a
softer acceleration method. However in many cases the practical differ-
ences between functions 1-4 will be very small.
If there is additional rigging and/or a fixture attached to the LT360, the
rigidity and mass of the additional hardware will play an important factor in
the overall motional system response. No mechanical structure is perfectly
rigid. When the LT360 platter begins to rotate, not all portions of the
attached rigging will instantly follow this same motion. The fixture will bend,
and can behave with its own time constant and perhaps ringing to the
rotational motion. The ringing motion or vibration will be controlled by the
damping in the fixture. Proper design of fixtures often requires damping
elements such as rubber pads placed between joints to increase damping.
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