Any way to read rotation without a sensor?

Well no one’s responding to my forum post detaling my bug in my auton and I have the tournament in three days, so I decided to code a (maybe) fix. It uses an inertial sensor. However I’m an idiot and thought we had them in the back, we don’t. Any way to get some kind of rotation sensor without it being a rotation sensor, in any capacity? Or any other kind of workaround to read the rotation of the bot?

If you don’t have any sensors you could use, you could get the heading from the drive’s motor encoders. Typically you would use separate unpowered wheels for this, but it doesn’t look like you will be able to implement it in the short time you have. It won’t be as accurate though. This is the equation for finding the change in angle:

∆θ = ( ∆L - ∆R ) / ( S_L + S_R )

∆L and ∆R are the change in wheel positions in the left and right wheels and S_L and S_R are the left-right distances between the wheels and the center of the robot.

If you want more information, you can refer to these posts:


As @xTigr has mentioned, that is a way to know your rotation without a sensor. However, a large issue is that it may not be as accurate as of the specialized sensor. I personally have never used the method given, but I believe that slipping in the wheels may reduce accuracy along with multiple other factors.

isn’t there a built in potentiometer in every smart Motor

There’s some kind of sensor built in for tracking the degrees/position. I don’t know the specific name, but it’s the drive motor encoders that were previously mentioned.

The motors have a built in encoder and have the ability to read rotation, you can see it on the devices tab in the brain. Now how to record rotations or utilize rotations I am not sure, I think its limited to programming the motor to move x amount of rotations.

They are not stepper motors.

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Your right sorry, I just reread the v5 motor description. They are in fact not stepper motors, but they do have a motor encoder that can read rotations, my bad I’ll edit my original comment