SMAC
LAC-26 Technical Reference Manual
4/29/2013 18
Command:
aSAn -- Set Acceleration --
Argument:
0 <= n < 1,073,741,823
Default:
0
This command sets the acceleration rate for servo axis 'a'. The 32 bit argument to this command
is scaled by 65536. This number determines how much the servo's velocity will be altered by each servo
loop interval (determined by the Servo Speed "SS" command) while it is accelerating or decelerating. If
this command is executed during a Position Mode move, it will be ignored.
Example:
Encoder: 500 lines or 2000 Counts/Rev
Desired Acceleration: 75 Rev/Sec2
Servo Loop Interval: 1,000 Hz
9830.4 = ((75 Rev/Sec * 2000 Counts/Rev) / 1000 Hz2) * 65536
To achieve an acceleration of 75 Rev/Sec2, the command SA9830 would be issued. A simpler
way to calculate the acceleration argument would be to determine a constant for your application by
which to calculate desired acceleration.
131.072 = K = ((1 Rev/Sec * 2000 Counts/Rev) / 1000 Hz2) * 65536
9830.4 = 75 Rev/Sec * K
Please note that if the Set Acceleration
(SA) command
is used with
an argument
of "0",
then you have commanded the velocity
to change in steps of
zero which
means if the
servo is
stopped it will not be able to move, and if the servo is moving it will not be able to change velocity.
Related Commands: SS, SV
Command:
aSCn
-- Set Current Mode Gain --
Argument:
0 <= n <= 32,767
Default:
0
This command
sets the "current mode"
gain for servo axis 'a' used by Torque Mode (QM1
only, see QM command). This allows the response of the current error integrator to be adjusted to suit a
given application. A low SC value will provide slow response to load changes while a high SC value will
provide quick response to load changes. If SC is set is too low then inadequate control may occur. If the
SC setting is too high then the system may be unstable. A good "general" value for SC is about 8000.
Related Commands: QM, SQ
Command:
aSDn
-- Set Derivative Gain --
Argument:
0 <= n <= 32,767
Default:
0
This command sets the derivative gain term of the PID digital filter loop for servo axis 'a'.
Related Commands: SG, SI, IL
