Mini map display on the Dashboard

[Invictus3593]

No matter how many corrections I tried, I could not maintain a reasonable value for position for more than about 10 seconds. Any small error in acceleration measurement is compounded when you integrate to get velocity, and any small error in velocity is further compounded when you integrate to get position. All of these errors sum up very quickly. As far as I can tell, the kit accelerometer simply does not have enough precision to be used in this way (although I would really like to be proven wrong). The sample times could also be an issue if a higher-precision accelerometer were used, but I am convinced that the limiting factor when using the kit accelerometer is its precision, not the sample times.

This is why I lean more towards the encoder/gyro method. Too many variables and errors in the accelerometer. But I may find that the encoder method has them too, only one way to find out. I'm gonna convince a few members of my team to help me work on an encoder/omni-wheel/gyro project with a kit chassis and give you guys an update in a few weeks.

Any suggestions before I start?

EDIT: The next thing after a mechanical solution has been found would be how to plot all this data on a 2D x&y plane on your dashboard in real time. I'm guessing the DB would do all the calculations and just get a couple SD Variables for encoders and gyro from the bot?

[Caleb Sykes]

Originally Posted by Invictus3593

Any suggestions before I start?

Study up on your trigonometry and dimensional analysis.

On an unrelated note, make sure that your wheels are not pushing too hard on the ground, or you might be sacrificing some acceleration/pushing power come competition.

[Invictus3593]

Originally Posted by inkling16

Study up on your trigonometry and dimensional analysis.

I've already been graphing test data (both encoders and a sample angle) in Microsoft Mathematics. I think I've got the graphing figured out.

Inputs:
ΔX and ΔY relative to the robot
Δangle relative to the last angle

Once one has these variables, they can use the rotateXY block in the geometry library to translate the whole thing to whatever angle is given by θ, the gyro.

Please correct me if I'm wrong on any of this.

On an unrelated note, make sure that your wheels are not pushing too hard on the ground, or you might be sacrificing some acceleration/pushing power come competition.

Good idea! Do you think they need to be spring-loaded in the case that a robot gets tipped a bit?

[Kevin Phan]

Here's the code for the minimap. It currently has only the rotation function working. You can observe how the image moves across the field. You can probably tell where I went wrong.

[Invictus3593]

Originally Posted by Kevin Phan

Here's the code for the minimap. It currently has only the rotation function working. You can observe how the image moves across the field. You can probably tell where I went wrong.

Wow! awesome job! I was able to map that rotation to a knob control and rotate a picture, but once I've turned the picture, it keeps the box where it originally was.

Before rotation:


At a 60-degree angle:


Did you get this too when you tested? It may be because the image I used wasn't the one you tested with.

[Kevin Phan]

What I found while testing the rotation display on the minimap was that you need to have a center of rotation lined up close. If you look at the code for the rotation, you can see that I set the center of rotation close to middle of the image. I thought I had folder called photo along with it...

[Kevin Phan]

Here's the folder for the picture on the mini map. Place it in Program files and in the FRC Dashboard and the minimap should work, if you haven't change the path to the files of the picture on the Dashboard.

[Invictus3593]

Originally Posted by Kevin Phan

Here's the folder for the picture on the mini map. Place it in Program files and in the FRC Dashboard and the minimap should work, if you haven't change the path to the files of the picture on the Dashboard.

This worked. For the movement in the XY plane, is the box created by the robot picture movable? If not, it may be beneficial to try having two pixmaps, one for the field and one for the robot. The robot pixmap could then be moved around the field by use of property nodes and rotated based on your rotation code.

I'll see if I can get to work on that.