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Unread 22-01-2017, 00:02
laura1640 laura1640 is offline
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Re: swerve drive

Hello,

On our swerve modules, we use two different sensors. One is to determine the angle that the wheel is pointed to. Like others have said, this is an absolute analog sensor. This is helpful because regardless of what angle the swerve modules are facing when the robot is powered on, they will still read the correct angle. Each of these sensors gets plugged into one of the 4 analog IO ports on the roborio.

The second encoder is used to determine the distance that the pivot has moved, similar to other drivetrains. This is mostly useful in autonomous, where the distance the robot travels needs to be exact. These sensors can be plugged into the digital IO ports on the roborio.

Also, may I ask what version of our code you are looking at (as in what year)?

~Laura
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Unread 22-01-2017, 12:57
Aslihanokur Aslihanokur is offline
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Re: swerve drive

Quote:
Originally Posted by laura1640 View Post
Hello,

On our swerve modules, we use two different sensors. One is to determine the angle that the wheel is pointed to. Like others have said, this is an absolute analog sensor. This is helpful because regardless of what angle the swerve modules are facing when the robot is powered on, they will still read the correct angle. Each of these sensors gets plugged into one of the 4 analog IO ports on the roborio.

The second encoder is used to determine the distance that the pivot has moved, similar to other drivetrains. This is mostly useful in autonomous, where the distance the robot travels needs to be exact. These sensors can be plugged into the digital IO ports on the roborio.

Also, may I ask what version of our code you are looking at (as in what year)?

~Laura
We used the codes that you wrote at 2012-Rebound Rumble. I wonder if we can set the swerve drive without absolute encoders. We reshaped our codes and made some replacement on our electronics. Actually it worked.However, ıt got the point that start at the begining as zero so that we need to make all 4 wheels at the same position before we send codes the robot. Are there any solution except using an absolute encoder?
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Unread 23-01-2017, 11:10
laura1640 laura1640 is offline
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laura1640 is a jewel in the roughlaura1640 is a jewel in the roughlaura1640 is a jewel in the rough
Re: swerve drive

If you wish, you can get some more recent code from https://github.com/frc1640. The past few repositories also have Java code for swerve if you are interested.

Using an absolute encoder will save a lot of trouble. You could try saving the value of the encoders to a file and use the last values to initialize the position the next time you power the robot on. However, if someone moves the pivots while the robot is off, it will cause problems. I would advise looking into adding an absolute encoder to your swerve for convenience.

~Laura
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Unread 23-01-2017, 12:51
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Re: swerve drive

Quote:
Originally Posted by Aslihanokur View Post
We used the codes that you wrote at 2012-Rebound Rumble. I wonder if we can set the swerve drive without absolute encoders. We reshaped our codes and made some replacement on our electronics. Actually it worked.However, ıt got the point that start at the begining as zero so that we need to make all 4 wheels at the same position before we send codes the robot. Are there any solution except using an absolute encoder?
Some teams use a magnet and a hall effect sensor to set the "zero" position for the module. Or, you could use a jig of some kind to align all the wheels at the start of the match.
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