SPRUHJ1I January 2013 – October 2021 TMS320F2802-Q1 , TMS320F28026-Q1 , TMS320F28026F , TMS320F28027-Q1 , TMS320F28027F , TMS320F28027F-Q1 , TMS320F28052-Q1 , TMS320F28052F , TMS320F28052F-Q1 , TMS320F28052M , TMS320F28052M-Q1 , TMS320F28054-Q1 , TMS320F28054F , TMS320F28054F-Q1 , TMS320F28054M , TMS320F28054M-Q1 , TMS320F2806-Q1 , TMS320F28062-Q1 , TMS320F28062F , TMS320F28062F-Q1 , TMS320F28068F , TMS320F28068M , TMS320F28069-Q1 , TMS320F28069F , TMS320F28069F-Q1 , TMS320F28069M , TMS320F28069M-Q1
Profile tracking tests how well the controller follows a changing target speed. The two metrics to evaluate in this testing are the maximum error and the absolute average error. The maximum speed error shows how much the controller overshoots while changing speeds. This is an indication of how aggressively your controller is tuned. If you controller is not tuned aggressively enough, the speed will overshoot the target, and will take a long time to recover. If the controller is tuned too aggressively it will overshoot, and then oscillate as it settles on the goal speed. If the controller is correctly tuned, it will overshoot and then smoothly return to the goal speed.
Absolute average error is an average of the absolute value of the instantaneous speed error over the entire profile. This measure shows the amount of deviation throughout the entire profile. It takes into account all of the little errors as the motor is running. If the controller is tuned too aggressively it will result in larger absolute average error because the controller will be oscillating throughout the profile. If the controller is not tuned aggressively enough, it will result in a larger absolute average error because it is continuously falling behind what the profile is commanding the motor to do.
Figure 13-10 shows the difference between the default tuning and the optimal tuning of the same controller. As you can see by tuning the speed controller, you are able to make your motion system much more closely track the reference. By tuning the controller, it greatly reduces the maximum error, the absolute average error, and the maximum overshoot.
It is important to test multiple speeds and accelerations in your profile as well as multiple different loads. Speed controllers have different performance characteristics when placed into different situations. In order to properly evaluate the effectiveness of your speed controller, tests should be conducted across the entire application range. This includes when you design the profile for testing. Care needs to be taken to ensure that the application speeds and accelerations are built into the profile. The results of these tests will inform you if your controller will meet the application specifications or if your controller needs to be tuned multiple times for different operating points.
It is also important to be able to create repeatable profiles and loads. Creating a repeatable profile can be done using SpinTAC Velocity Move and SpinTAC Velocity Plan; for more information, see Section 14. Repeatable profiles are required so that all controllers will be tested using the same reference in the same order and for the same length of time. This ensures that test conditions are as identical as possible. When applying load during a profile tracking test it is important to create repeatable disturbances. This can be accomplished using a dynamometer or a disturbance motor. Creating a repeatable disturbance is an important factor when evaluating controllers. If test conditions cannot be replicated, it is difficult to adequately compare the responses of two controllers.