2.4.2.4 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.
2.4.2.4.1 Prerequisites
Before conducting system identification make sure that:
1. The motor is connected and functional.
2. The system is firmly fixed.
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 output sensible data.
6. Applying constant positive torque results in positive velocity and vice versa.
Note
Using a Chopper Board is strongly recommended to prevent hardware damage
2.4.2.4.2 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 the 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.
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