OMS MAXnet, Руководство пользователя

Страница: 18 / 67

GETTING STARTED TUNE THE SYSTEM
2-12 MAXnet User’s Manual
compensated for using the feedforward coefficients explained later in this section. There are some
general formulas that have been developed to determine acceptable “Following Error” for both current
and velocity mode systems:
Current mode "Following Error" for:
KP = (3

/360

)

(counts per revolution)
Voltage mode "Following Error" for:
KP = (90

/360

)

(counts per revolution)
It is obvious that the voltage mode allows for much greater “Following Errors” than the current mode.
This value is the “Following Error” when the motor is at peak velocity and will be used when determining
the proportional gain (KP).
The "Following Error" for the integral term (KI) or long-term gain value will follow the guidelines below:
Current Mode “Following Error” for:
KI = 0 counts
Voltage Mode “Following Error” for:
KI = 80

of 360

(expressed in motor counts)
While still in open-loop mode (CL0;) use the KO command to zero the motor. This variable is used to
provide a constant output that will compensate for torque offset from the load. So, when the system
should be stationary, the necessary voltage will be sent to the amplifier to cause the motor to maintain
position. With the correct KO value, the motor should successfully maintain a zero position.
KO is the offset coefficient used while in closed-loop or open loop mode, hold on (HN). You should have
determined the correct value the KO variable before beginning to tune the PID filter.
The values for KO range from –32640 to 32640.
Set the known values for velocity, acceleration and the move distance for a trapezoidal profile with at
least a 20% flat spot at peak velocity. Formula:
Profile distance = ((peak velocity)^2/(2

acceleration))

2.4
Example: ((50,000)^2/(2

500,000))

2.4 = 6,000
Execute the move by sending the move commands to the MAXnet.
Example: MR6000;
GO;
Adjust the KP term while repeating step 3 until the “Following Error” at the flat spot of the profile is
acceptable. If the motor becomes unstable prior to obtaining the optimum KP term, then increase the
KD term until the motor stabilizes.
Example: LP0;
KP3;
CL1;
MR6000;
GO;
LP0;
KP10;