Page 743 - Mechatronics with Experiments

PROGRAMMABLE MOTION CONTROL SYSTEMS 729
Wait until Home_Sensor = ON
MoveAt (Zero_Speed, Stop_Rate)

% Jog Motion
MoveAt (Jog_Speed, t_acc )
Wait until Jog_Stop=ON
MoveAt (0, Stop_Rate)

% Stop motion
MoveAt (0, Stop_Rate)
% Index motion

MoveFor (Index_Value, t_acc, t_run, t_dec )

%

10.5 COORDINATED MOTION CONTROL METHODS

In PMCS that involve multiple actuators (also called multi degrees of freedom or multi axis
motion control system), the motion coordination (synchronization) between different axes
can be categorized as follows (Figure 10.11):
1. point-to-point control applications (insertion machines, assembly machines, pick-
and-place machines),
2. speed ratio (electronic gearing) applications (coil winding, packaging, printing, paper
cutting, web handling machines),
3. contouring applications (CNC machine tools, robots, laser cutting machines, knitting
machines),
4. sensor based motion planning and autonomous motion control.
There are two very common motion coordination methods in the web handling automation
industry and they use some of the above coordination methods. They are
1. motion coordination using a “registration” signal from an external sensor (also called
registration application),
2. tension control applications (paper, plastic, wire handling machines).
Both of these applications use electronic gearing as the basis of motion coordination and
add a motion modification to it based on the external sensor (registration sensor or tension
sensor).

10.5.1 Point-to-point Synchronized Motion

Point-to-point position synchronization refers to the positioning of one axis or more with
respect to another axis at a selected number of points during a cycle. In this type of
application, there are a finite number of important points during each cycle where the
relative positions are critical, that is in insertion applications, the pin and the housing must
be properly positioned right before the insertion takes place. When an axis (master) is
in a certain position, the other axis (slave) must be in a certain position relative to the
master axis. The relative position of the slave with respect to the master is important at