Danfoss MCO 305 Design Manual page 53

MCO 305 Design Guide
__ Functions and Examples __
Next chart is similar to the previous example
except that it begins with a positive acceleration. In
this case, the curve must start with an acceleration
ramp-down segment (using JERKMIN2). Once the
acceleration reaches 0, then the curve can continue
as before.
The chart below shows a movement that begins with a negative constant velocity and changes direction to a
positive constant velocity. The curve must start by slowing down the speed so that it can 'turn around'. Hence
the curve begins with a deceleration ramp-up segment (using JERKMIN3) until it reaches maximum deceleration.
The deceleration continues at maximum decele-
ration until it reaches 0 velocity. Note that there is
no deceleration ramp-down segment because the
movement is not stopping. At exactly 0 velocity,
the direction reverses and the movement is now
accelerating in the other direction. But since maxi-
mum acceleration is higher than maximum decele-
ration for this example, the curve is now able to
include an acceleration ramp-up segment (using
JERKMIN). The curve finishes in the normal way
with a constant acceleration segment and an
acceleration ramp-down segment to constant
velocity (using JERKMIN2).
Moving to a Specified Position
The chart below shows a 'normal' movement from being stopped at one position and then moving forward
to stop at another position. The curve starts with an acceleration ramp to maximum velocity. This portion of
the curve will be similar to the first of the examples shown in "Changing to a Constant Velocity". The curve
is simply changing to a constant velocity where the constant velocity is the maximum velocity.
Hence, the curve will consist of an acceleration ramp-up segment (using JERKMIN), a constant acceleration
segment at maximum acceleration, and then an acceleration ramp-down segment to maximum velocity
(using JERKMIN2).
The movement then proceeds at maximum velocity
until it needs to start the deceleration ramp that
will stop the movement at the desired position. The
deceleration ramp is identical to the first of the
examples shown in "Stopping". The curve will
consist of a deceleration ramp-up segment
(JERKMIN3), followed by a constant deceleration
segment (at maximum deceleration), and finally a
deceleration ramp-down segment to 0 velocity
(using JERKMIN4) stopping at the desired position.
53
®
MG.33.L5.02 – VLT is a registered Danfoss trademark