1.5.2.4 System Identification
An open-loop system identification extracts a mathematical model of an electromechanical system
from a frequency response. The obtained model is then used during the auto-tuning procedure.
1.5.2.4.1 Prerequisites
Before conducting any system identification activities make sure that:
1. The motor is connected and functional
2. The system is fixed firmly
3. The motor shaft can rotate
4. The torque control loop is functional and the commutation offset is found
5. Position and velocity signals are present and give sensible data
6. Applying constant positive torque results in positive velocity and vice versa
Note
Note
Using a Chopper Board is strongly recommended to prevent hardware damage
Using a Chopper Board is strongly recommended to prevent hardware damage
1.5.2.4.2 Limitations
1. The procedure should be used carefully if the system has strict mechanical limitations. Torque
amplitude should be decreased until safe identification is possible
2. If the system is highly non-linear, the identified model might differ from reality
3. If motion and vibration are too high, the algorithm can’t be used
4. The accurate frequency response of the system can be obtained only for frequencies up to 100 Hz
due to communication limitations.
5. If the system has very high static friction, small amplitude torque signal will overestimate viscous
friction and inertia.
Commissioning and Tuning with SOMANET OBLAC Drives
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