Too much turn

[PrathinSrinarayanan]

Hi, I'm a beginner, and I don't know much about coding robots with python. This is what I got so far:

from pybricks.hubs import PrimeHub
from pybricks.pupdevices import Motor, ColorSensor, UltrasonicSensor, ForceSensor
from pybricks.parameters import Button, Color, Direction, Port, Side, Stop, Axis
from pybricks.robotics import DriveBase
from pybricks.tools import wait, StopWatch


hub = PrimeHub()

left_motor = Motor(Port.A, Direction.COUNTERCLOCKWISE)
right_motor = Motor(Port.B, Direction.CLOCKWISE)
drive_base = DriveBase(left_motor, right_motor, wheel_diameter=56, axle_track=104)

drive_base.use_gyro(True)

drive_base.turn(90)

My robot isn't turning 90 degrees though, and I'm trying to use the gyro.

[dlech]

What happened instead? Did it turn a different amount or did it not do anything at all?

[PrathinSrinarayanan]

It turned, but the angle was way too much

[dlech]

Which direction is the hub mounted?

See https://docs.pybricks.com/en/stable/signaltypes.html#reference-frames

Does it look like one of those pictures or something else?

[PrathinSrinarayanan]

Axis X is the front side and Axis Z is the top side

[laurensvalk]

When your program ends, the motors stop, so it also stops correcting. To get a better picture, you could add a wait block to wait a few seconds to prevent the program from ending right away.

Also be sure to accurately measure the dimensions and check out these tips. They explain what to do if the robot turns too far or not far enough.

[PrathinSrinarayanan]

I have now measured the diameter and wheelbase with a ruler and added wait(20) at the end. this is my new code. any tweaks to add?

from pybricks.hubs import PrimeHub
from pybricks.pupdevices import Motor, ColorSensor, UltrasonicSensor, ForceSensor
from pybricks.parameters import Button, Color, Direction, Port, Side, Stop, Axis
from pybricks.robotics import DriveBase
from pybricks.tools import wait, StopWatch


hub = PrimeHub()

front_side = Axis.X
top_side = Axis.Z

left_motor = Motor(Port.A, Direction.COUNTERCLOCKWISE)
right_motor = Motor(Port.B, Direction.CLOCKWISE)
drive_base = DriveBase(left_motor, right_motor, wheel_diameter=56, axle_track=80)

drive_base.use_gyro(True)

drive_base.turn(90)
wait(20)

[laurensvalk]

The wait is just for testing in this case. You don't need it in your final program.

Yes, if you measured the axle track as 80, it makes sense that it wouldn't work great with a value of 104 as before.