limite angle value in DriveBase.curve(radius, angle, then, wait) ???

[deopark]

Using the code below, we are trying to make a function to curve for a given amount of time.

db = DriveBase(left_motor, right_motor, diameter, axle_track)
db.curve(radius, angle, then=Stop.NONE, wait=False)
wait(milliseconds)
db.brake()

However, the angle parameter of the DriveBase.curve() has limitations. (It raises a ValueError if it is over)
We found out that it is related to the straight_speed, turn_rate(DriveBase.settings()), radius parameter, and wheel diameter.

To complete the code above, we need to find the maximum angle value(each situation).
Is there a way to calculate it?

The reason we avoid using smaller angle values is that acceleration also stops once the DriveBase.curve() is done.

Otherwise, Is there a better code for curving for time?

[laurensvalk]

Which parameters have you tried, and which do not work?

[deopark]

Thank you for your response.

Please review the following code. We are coding a curve function with time as a parameter.

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

prime_hub = PrimeHub(top_side=Axis.Z, front_side=Axis.Y)
left = Motor(Port.A, Direction.COUNTERCLOCKWISE)
right = Motor(Port.B, Direction.CLOCKWISE)

drive_base = DriveBase(left, right, 62.4, 160)

def curve_for_time(radius, time):
    drive_base.settings(straight_speed=217, turn_rate=130)
    print(drive_base.settings())

    # angle=33310 -> ValueError
    drive_base.curve(radius, angle=33309, then=Stop.NONE, wait=False)
    wait(2000)
    drive_base.brake()

    wait(500)
    print(drive_base.done())

curve_for_time(200, 2.5)

It works as we intended.

However, the curve method raises a ValueError if the angle value increases by even 1.
And this maximum executable value depends on the straight_speed, turn_rate, and wheel_diameter.

We want to know how the maximum angle value is calculated.
We want to calculate the maximum angle value that does not raise ValueError, even if straight_speed, turn_rate, and wheel_diameter change.

[laurensvalk]

We limit some input values to practical ranges to ensure valid calculations of the math that happens on the robot.

This ensures there is never any unexpected motions due to math operations overflowing internally.

angle=33310 -> ValueError

An angle of angle=33309 is almost a 100 full rotations of the robot, which seems unusually high.

Even if you intended to make a function to drive for time, would you expect to need 100 rotations in one move?

[deopark]

That's correct. It's an unnecessarily large number.

We only want to know the valid maximum value (one that doesn't raise errors).

When all related variables decrease(or increase), the angle value needs to be reduced to approximately 760(about 2 rotations).
( related variables are straight_speed, turn_rate, wheel_diameter, and radius)
also, When the radius increases, the angle value needs to be lower to avoid exception.

Of course, such conditions are not common, but it would be helpful to know the internal formula to calculate a safe maximum value each time the function is called.

drive_base = DriveBase(left, right, 40, 160)
def curve_for_time(radius, time):

    drive_base.settings(straight_speed=5, turn_rate=10)
    print(drive_base.settings())

    # at small tire, low speeds, limit 762 degrees 
    drive_base.curve(radius, angle=762, then=Stop.NONE, wait=False)
    wait(time * 1000)
    drive_base.brake()

    wait(500 )
    print(drive_base.done())

curve_for_time(200, 2.5)

If it's not easy,
we will continue to think about other approaches.