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Unread 13-02-2015, 15:58
slibert slibert is offline
Software Mentor
AKA: Scott Libert
FRC #2465 (Kauaibots)
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Re: ANNOUNCING: navX MXP Robotics Navigation Sensor

Quote:
Originally Posted by rich2202 View Post
Any comments on using the navX with Mecanum wheels?

In the wpilib, there is a gyro parameter that you can pass to the Mecanum function. Can navX provide the gryo input? Or, does the navX libraries have Mecanum drive?
Team 2465 (Kauaibots) uses navX MXP w/Mecanum, it works great.

We found the key to good mecanum was both Field-Oriented Drive (which the navX MXP provides), and traction control (implemented via speed-control PIDs on each of the wheels). Additionally, the navX MXP allows an "auto-rotate to angle" feature, which is helpful in two ways: (a) it lets drivers push a button and have the robot line itself parallel (or perpendicular) to the field, and (b) if used while strafing, it helps the robot stay aligned with the head of robot pointing to the "head" of the field, even if the load on the mecanum drive-train is uneven.

Java Source code for the drive subsystem that implements this is available here. This demonstrates the use of the nav6 or the navX MXP. Drive.java is provided a reference to the IMU object when it is constructed, and then uses it internally.

The IMU class (for C++/Java) also implements the PIDSource interface, so you can use it with other classes that use a PIDSource for gyro input.

Last edited by slibert : 13-02-2015 at 16:07.
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