ASDA Series Application Note Application Examples
March, 2015 3-77
3.5.3.3 Steps for Adjusting the Servo when Using Gantry Control
The following steps are about the gantry setting and parameter adjusting.
Step 1: Check the wiring
Please refer to the application in section 3.5.3.1 and make sure the wiring is correct.
Step 2: Set up the inertia ratio of the system
Pause the gantry function. Check all the settings of every mechanism and servo drive such as
emergency stop and positive/negative limit. Adjust the mode to J-L (for inertia monitoring) via
monitoring panels of the two servo drives. Let the host controller issue a pulse command and
make the gantry mechanism move back and forth with low speed so as to make sure the
mechanism is working fine. Then, gradually speed up the gantry and monitor the inertia
displayed on the panel. Wait until the inertia becomes stable and then write the inertia ratio into
parameter P1-37 of each controller respectively (When mechanism structure is asymmetric,
inertia ratio will vary with each controller). Inertia ratio is the calculation basis for servo motors’
operation; this value must be correct.
Step 3: Output pulse setting for monitoring
Concerning the use of gantry synchronization, it is important to consider controller’s receiving
speed of monitoring pulse (which is CN5’s capability of pulse receiving). The limit is calculated as
below.
6
10*84*461*
60
P
MotorSpeed
Calculation Example:
The pulse command from one host controller at maximum speed is 50000 pulse/s. And the
E-gear ratio is 20 times. When the encoder completes a full rotation, the feedback pulse is
1280000 (without going through the E-gear).
(Pulse command * E-gear ratio) / Actual pulse number * 60 sec. = Motor speed per minute
(RPM),
(50000 * 20) / 1280000 * 60 = 46.875 RPM = the maximum motor speed set by the control
command
Based on the above formula, the permitted maximum setting value of P1-46 (Pulse Number of
Encoder Output) can be decided. Improper gain adjusting on a controller might lead to speed
overshoot when the motor is operating; meanwhile, the motor speed might exceed the maximum
speed set by the command; therefore, the overshoot level should be taken into consideration.
For instance, if a margin of 10% is reserved, it has to be increased depending on the
circumstances when using special mechanism.
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