Integrating the Accelerometer

[apalrd]

Assuming you are driving with wheels, encoders can get you almost exactly where you want to go. They measure the exact rotational travel the wheels move, and from there you can calculate your exact displacement and velocity. They (along with the gyro) are my favorite autonomous navigation sensors.

Edit: Beaten to it.

[mwtidd]

Originally Posted by apalrd

Assuming you are driving with wheels, encoders can get you almost exactly where you want to go. They measure the exact rotational travel the wheels move, and from there you can calculate your exact displacement and velocity. They (along with the gyro) are my favorite autonomous navigation sensors.

Edit: Beaten to it.

Or use the camera so location is never an issue. Encoders and gyros require correct orientation of the robot from the start. This year there is nothing to square your robot against. For this game, I think that a compass may be helpful to zero the gyro at the start. Then encoders should be sufficient for driving straight for a certain distance.

[Jogo]

Thanks for the feedback.

As far as encoders...I don't really know how well those will do because we are using mecanum.

[Slix]

Originally Posted by Jogo

Thanks for the feedback.

As far as encoders...I don't really know how well those will do because we are using mecanum.

I have the same question. Will encoders work for measuring distance while using mecanum wheels?

I'm also worried about having the robot correctly oriented so that gyro angle zero is exactly perpendicular to the front of the field. Otherwise, we wouldn't get perfect results.. is this going to be a huge problem for autonomous?

[jhersh]

Originally Posted by Slix

I have the same question. Will encoders work for measuring distance while using mecanum wheels?

They can work, but they are much less tolerant of the robot from not being flat and lumps in the carpet, etc. Your driver will naturally compensate for these things, but the sensor just measures what's really happening.

Also note that the encoder is measuring the wheel rotations, which for mecanum wheels does not directly translate into distance = circumference * rotations. You will have to invert the mecanum control equations to make sense of the 4 wheel position channels.

[Joe Ross]

It would probably be easier to put encoders on two unpowered omni-wheels that are 90 degrees from each other.

Something similar to http://www.chiefdelphi.com/media/photos/32440