User Manual
Chapter 15
GFK-1742F
Jan 2020
Using the Electronic CAM Feature
331
Note:
•
For a given master position X, that lies between X
n-1
and X
n
, the coefficients A, B and C are selected
for the point corresponding to X
n-1
.
•
For a second order curve-fit, the A coefficient is always zero, and for a first order curve-fit, both the
A and B coefficients are always zero.
Blending Sectors
The process applied to blend adjacent sectors depends on their curve-fit order. The
following descriptions cover the possible scenarios.
1
st
order to 1
st
order
No action is taken to smooth the transition between successive linear sectors (that is, with
curve-fit order of 1). The profile simply connects the end point of one sector to the start
point of the next with a straight line.
1
st
order to 2
nd
order
When a quadratic (2
nd
order) sector follows a linear (1
st
order) sector, the polynomial
coefficients for the first segment of the quadratic sector are calculated so that the slope of
the profile is equal on either side of the starting point of that sector. That is, the initial slope
of the quadratic sector is made equal to the final slope of the linear sector.
2
nd
order to 1
st
order
When a linear (1
st
order) sector follows a quadratic (2
nd
order) sector no action is taken to
smooth the transition. This type of transition is not recommended (if it is avoidable) as it
may result in drastic velocity or acceleration changes on the controlled servo.
2
nd
order to 2
nd
order
When a quadratic (2
nd
order) sector follows another quadratic (2
nd
order) sector the
polynomial coefficients for the first segment of the second quadratic sector are calculated
so that the slope of the profile is equal on either side of the starting point of that sector. That
is, the initial slope of the second quadratic sector is made equal to the final slope of the first
quadratic sector.
2
nd
order to 3
rd
order
When a cubic (3
rd
order) sector follows a quadratic (2
nd
order) sector the polynomial
coefficients for the first segment of the cubic sector are calculated so that the slope of the
profile is equal on either side of the starting point of that sector. That is, the initial slope of
the cubic sector is made equal to the final slope of the quadratic sector.
3
rd
order to 2
nd
order
When a quadratic (2
nd
order) sector follows a cubic (3
rd
order) sector the polynomial
coefficients for the first segment of the quadratic sector are calculated so that the slope of
the profile is equal on either side of the starting point of that sector. That is, the initial slope
of the quadratic sector is made equal to the final slope of the cubic sector.