VEX GO Gyro Accuracy

Programming Support
1

Hello!

Sorry probably not the correct category but I can’t find any categories for VEX GO and VEX 123 products.

We are having some problems with the VEX GO robots, specifically with driving straight and turning. It seems that the gyro sensors in the VEX GO brains are not particularly accurate which makes it tricky to carry out the STEM lab exercises. In short, driving straight for more than 20cm will make the robot veer one way or the other and turning needs large adjustements to corrcet. For example on most units a turn of around 78 to 80 degrees needs to be set to ensure that the actual robot turns 90 degrees. So in effect the sensor reports a full turn as around 320 degrees which might also contribute to the problem of driving straight.

We have tried to rule out any outside influences as much as possible (wheels, cables, surface etc.) but haven’t been able to achieve much success. It kind of works but the ‘drift’ or repeatability is such that the exerceises are difficult because after a short movement the robot is not in a space and orientation where we expect it to be and subsequent commands fail to achieve the goals.

Does anyone have experience with the VEX GO kits and can maybe suggest some improvements? Unfortunately on the VEX GO coding side there is very little functionality to compensate for these issues.

Any help would be appreciated!
Mike

2

If you tick the box next to Gyro Heading in Degrees, you will then be able to see the Gyro reading in the Monitor (click the little speedometer icon next to the devices button).

Rotate the robot through 360 degrees and see if the heading value is accurate. Repeat a few times to see of you are seeing the same level of discrepancy there.

Also, for comparison, try connecting to the robot using a windows laptop (codego.vex.com) and try the same code to see if it is any different.

1 Like
3

Thanks a lot for your reply!

Ah, that is interesting. The readout on the tablet is different from the Windows laptop. On the laptop the full circle is near enough 360 degrees but when using the Android tablets the full circle is about 320 degrees. Strange! Any ideas why that might be?

4

@jpalnick is best placed to answer this.