Inertia Estimation; Precautions For Inertia Estimation - Delta ASDA-A3 Series User Manual

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5.2 Inertia estimation

Whether the load inertia ratio (P1.037) is correctly set affects the speed loop bandwidth of the

servo drive. If set incorrectly, the system's performance cannot be optimized after tuning.

When you use the functions of One Touch Tuning, Auto Tuning, or Gain adjustment mode 1

(Level adjustment - Auto) with ASDA-Soft, the servo drive automatically estimates the load

inertia during the tuning process. If not using the preceding functions, you can directly use the

Inertia (Weight) Estimation function.

The estimation of load inertia can be done without the controller's command. During the

estimation process, the motors runs back-and-forth in the forward and reverse directions.

If the inertia estimation cannot be done or the inertia cannot be correctly estimated in the

system, estimate the load inertia ratio by yourself and set P1.037 with the estimated value.

Recommended settings for inertia estimation

1. Jog speed: 500 rpm or above.

2. Acceleration time from 0 rpm to 3000 rpm or deceleration time from 3,000 rpm to 0 rpm:

within 200 ms.

3. Traveling distance: 1 revolution or above.

Description: if the estimated load inertia cannot be reduced to a stable value, increase the jog

speed first. If the traveling distance is too long, the estimation time is longer, too.

Inertia estimation cannot be done in the following systems

1. The mechanical part only moves in a single direction.

2. The movement speed of the mechanical part is lower than 200 rpm.

3. The traveling range of the mechanical part is shorter than the traveling distance when the

motor rotates 0.5 revolution.

Inertia cannot be correctly estimated in the following systems

1. The load inertia ratio of the mechanical part changes drastically.

2. The load inertia ratio of the mechanical part is greater than 50 times.

3. The bandwidth of the mechanical part is lower than 10 Hz.

4. The viscous friction of the mechanical part is high.

5. The torque limit of the mechanical part is too low.

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