6
Introduction
Page 10
User Manual for PMotion
6.3.2
Motion Generator Overview
The Motion Generator provides the ability for the user to create complex position mappings
between one axis and another. Before using the Motion Generator a number of issues need to
be understood:
•
You are designing a map shape which relates the position of the slave axis to the position
of the master axis at any point along the master axis. This is essentially a cam, although
you can do things that a cam could not. During the design of the map shape you will
determine the map shape using segments, and setting parameters for these segments.
•
Certain restrictions have been applied, by default, to the segment to segment boundaries
to ensure that the generated map shape is physically achievable:
Default segment boundary conditions:
Slave Derivative
Segment nn to Segment nn+1 boundary conditions (defaults)
Position
Match with previous:
The start position of segment nn+1 will match
the end position of segment nn. This cannot be altered.
Velocity
Match with previous:
The start velocity of segment nn+1 will
automatically be adjusted to match the end velocity of segment nn.
This may have the effect of modifying the shape of segment nn+1
which can lead to unexpected segment shapes. (For certain segment
types it is possible, but not advisable, to break this matching.)
Acceleration
No value specified:
For all segment types excluding polynomial and
cubic spline acceleration at the beginning of segment nn+1 is
determined by the segment type. Therefore there may be a step
change in acceleration across the nn to nn+1 segment boundary.
Match with previous:
A polynomial segment and the cubic spline
segment automatically matches their start acceleration to the end
acceleration of segment nn. For the polynomial segment alone this
matching can be broken.
Jerk
No value specified:
The jerk value at the beginning of segment nn+1
is determined by the segment type. Therefore there may be a step
change in jerk across the nn to nn+1 segment boundary.
For the polynomial segment alone it is possible to change this to
match with previous or specify the required value.
