Field Positioning with IMU

[zdwempe]

Hello all,

Lately, I have been working on our team's autonomous program. Essentially, we have decided what we want to do and are working toward accomplishing that. However, I have some questions regarding the motion planning aspect of the autonomous program.

The main presentation I have watched on motion planning is 254's from worlds a couple of years ago. They talk, at one point, about plotting a function that describes, in a mathematical way, the curved path which your robot takes. This makes perfect sense, and I absolutely love this idea. However, there is one major problem which I don't know how to solve. Whether I missed it in the presentation, it wasn't addressed as field conditions didn't necessitate it that year, or I just didn't understand it, I'm not sure. But my question is this:

What happens when you get knocked off course or off to the side of your pre-plotted path?

The encoders and PID control make sure your wheels spin the right amount to follow that path, but if your entire robot is oriented incorrectly or a foot off to the side, how do you know? I assume that's where the IMU comes in. Some combination of the accelerometer, gyro, and magnometer will give me orientation and position relative to starting position, and I use PID or something similar to bring that error to zero?

Sorry if this rambled, or asked questions that have already been answered.

Thanks,
zdwempe

EDIT: Forgot to mention that we're using the BNO055 IMU and Talon SRX Motor Controllers.