Implementing Feedforward/Feedback Motion Profile with Talon SRX

[sraque]

Originally Posted by Tparbotmail

Hi Steve
How did you get that .97 throttle value for the right side? Having trouble understanding.

We have a VI in Periodic Tasks that logs data to a file. We logged throttle setting and speed as reported from the Talon SRX status VI. We drove the robot at full speed (joystick full forward) down a hallway keeping it straight as much as we could, and then looked at the data log. We looked for areas of data where throttle and speed were close to constant and close to maximum and then took those as the data pairs. Since motors behave differently going forwards or backwards, it is typical that for driving straight, one side will be at a higher throttle than the other.

The important part is to get a relationship between throttle and speed. The process assumes the relationship is linear, and with today's speed controllers that is true. So, theoretically, you could pick your data pair anywhere along the line. Choosing a point near maximum throttle, however, will reduce your error resulting from variations that happen during the measurement process.