How to calibrate the polarity of your feedback device manually
Some of the feedback devices that the Ingenia Ecore line of servo drives have tools (Auto identify) in the MotionLab software in order to identify its polarity. This is the case with the digital/sin-cos encoder and the digital halls mainly and they can be found in their own windows inside the software. In addition to these particular tools, we also have the Configuration Wizard as a tool/process through which we can calibrate the polarity of the feedback devices in our system.
However, there are particular systems in which these tools sometimes fail and don't calibrate properly and we there are feedback devices that don't have such identification tool inside the software. This includes systems with gearboxes, systems with certain absolute encoders or systems with loads. In such cases, what process can we follow in order to calibrate the polarity of the feedback device so that we can proceed with the configuration?
- The first step that needs to be done is to set that particular feedback device as the Position sensor. You can set that up in the Actuator window like it is shown in the following picture (an example of a digital encoder):
- The second step is to introduce the basic data of the feedback, in case that this is needed. Introduce all the known data and select the Polarity of the device as Standard. Example of how to do that with a digital encoder is shown in the following image:
- After setting all the parameters of the feedback device, we need to open the Move window and use the Open-loop with "Internally generate commutation angle" mode in order to make the motor move. In order to do that, select a target voltage in the 2-15% range and a target frequency in the 250-2000mHz range so that the motors starts moving slowly but steadily. In parallel, you need to open the Scope and start plotting the position actual value register. If the position actual value register keeps increasing while the motor moves, then the selected Polarity is correct, otherwise, you need to select the alternative option.
- In this example, it can be seen that the position actually decreased, therefore we need to change the Polarity of the encoder to Reversed:
- After changing it and reproducing the same movement, it can be seen that the position now increases while the positive voltage is supplied:
- The last step that would need to be done would be to change the Position sensor in the case that the feedback device that we just calibrated was not used for position control. Otherwise, the process is finished.