User guide

➅ Advanced 6250 Features 81
❏ If you increase the A
avg
value above the pure S-
curve level (A
avg
> 1/2 A
max
), the time required
to reach the target velocity and the target
distance decreases; however, increasing A
avg
also increases jerk. After increasing A
avg
, you
can reduce the jerk by increasing A
max
(see
illustration); however, increasing A
max
requires greater torque from the motor
to achieve the commanded velocity at
the mid-point of the acceleration
profile.
T
V
➀ Original Profile
➁ After increasing A
avg
➂ After increasing A
max
❏ You can calculate the profile's accel/decel time with the following equations (calculation
method is identical for S-curve
and trapezoidal):
Time of accel or decel =
Velocity
A
avg
or Time of accel or decel =
√
2 ∗ Distance
A
avg
❏ Scaling (SCALE) affects A
avg
the same as it does for A
max
, regardless of if the profile is
trapezoidal or S-curve (see Scaling section in Chapter 5).
Example
Example Description
> ERES4ØØØ Set resolution to 4000 steps/rev
> SCALEØ Disable scaling
> MAØ Select incremental positioning mode
> @D5ØØØØ Set distances to 50,000 CW steps
> A1Ø,1Ø Set max. accel to 10 rps
2
(both axes)
> AA5,1Ø Set avg. accel to 5 rps
2
on axis 1,
and 10 rps
2
on axis 2
> AD1Ø,1Ø Set max. decel to 10 rps
2
(both axes)
> ADA5,1Ø Set avg. decel to 5 rps
2
on axis 1,
and 10 rps
2
on axis 2
> V5,5 Set velocity to 5 rps on both axes
>GO Execute motion on both axes
T
Axis 2
V
0123
T
Axis 1
V
0123
Axis 1 executes a pure S-curve profile that takes 1 second to reach a velocity of 5 rps and 1
second to return to zero velocity. Axis 2 executes a trapezoidal profile that takes 0.5 seconds
to reach a velocity of 5 rps and 0.5 seconds to return to zero velocity.
X-Y Linear Interpolation
The 6250 allows you to perform X-Y linear interpolation, the process of moving two
orthogonal (right angle) linear axes to achieve linear (straight line) motion. The task is to
derive appropriate move parameters to move from a current location to a new location, where
each position is specified by a set of Cartesian coordinates. Both axes must start, accelerate,
decelerate, and stop in a synchronized manner.
The Initiate Linear Interpolated Motion (GOL) command initiates linear interpolation moves
based on the parameters set with the D, PA, PAD, and PV commands. You simply enter the
desired path acceleration (PA), the path deceleration (PAD), and the path velocity (PV) to arrive
at the point in space (end point) specified with the distance (D) command; the 6250 internally
calculates each axis' actual move profiles to achieve a straight-line path with these parameters.
You can scale the acceleration, velocity, and distance with the PSCLA, PSCLV, and SCLD
commands, respectively (see example below).
The GOL command starts motion on either or both axes. If the GOL command is issued
without any arguments, motion will be started on both axes.