how to change initial condition observer rpm in dc motor?

i'm using observer to estimated rpm value in my dc motor. but my result is different between RPM real value and RPM estimation in the initial condition? how to solve this problem? what should i change?

[Joel Van Sickel]

is the problem the initial condition? It looks like they both start at 0. It looks more like the problem is an error around 300 rpm.

Answer 1

[Anurag Ojha]

Hello Muhammad,

As per my understanding, you are experiencing difference between the real RPM value and the estimated RPM value in the initial condition while using an observer for your DC motor, here are a few workarounds you can consider to address the problem:

1. Observer Gain Tuning: The observer gain plays a crucial role in accurately estimating the RPM value. Try adjusting the observer gain parameters to improve the accuracy of the estimation. Depending on the observer type, you may need to adjust different gain matrices or parameters.
2. System Modeling: Ensure that the DC motor is accurate and represents the real system dynamics as closely as possible. Any discrepancies between the model and the actual motor behavior can lead to estimation errors. Consider refining your motor based on more accurate parameters or experimental data.
3. Sensor Calibration: Check the calibration of the sensors you are using to measure the motor speed. If the sensors are not calibrated correctly, it can introduce errors in the measurements, leading to inaccurate RPM estimation. Verify the sensor specifications and calibration procedure to ensure accurate readings.
4. Initial Conditions: The accuracy of the observer estimation can be affected by the initial conditions. Ensure that setting the initial conditions of the observer correctly based on the known or measured values of the motor state variables. Incorrect initialization can lead to initial estimation errors, which might affect subsequent estimation accuracy.
5. Noise Filtering: Consider implementing appropriate filtering techniques to reduce noise in the sensor measurements. Noise can significantly impact the accuracy of the observer's estimation. Techniques like low-pass filtering or signal averaging can help improve the robustness of the estimation.
6. Observer Design: Evaluate the design of observer and check if it is suitable for specific DC motor system. Different observer designs might have different strengths and weaknesses, so it's worth exploring alternative observer types or configurations to improve the estimation accuracy.

The performance of the observer is influenced by above mentioned factors. Therefore, a combination of the above suggestions should help to improve the accuracy of the RPM estimation in the DC motor system.

Hope it helps!