Consistent speed/accel/turn speed/turn accel values?

[davidyang]

This is how we boot the hub:

# Set up all devices.
HUB = PrimeHub(top_side=Axis.Z, front_side=-Axis.X, broadcast_channel=0, observe_channels=[1])
# Left_Color_Sensor = ColorSensor(Port.B)
# Right_Color_Sensor = ColorSensor(Port.F)

left_motor = Motor(Port.C, Direction.COUNTERCLOCKWISE)
right_motor = Motor(Port.D, Direction.CLOCKWISE)


# 62.4 is rubber wheel
# 57mm small technic wheel

SMALL_TECHNIC_WHEEL_DIAMETER = 57 # TODO Fix for next year, it's more like 56
WHEEL_BASE = 145
DRIVE_BASE = DriveBase(left_motor, right_motor, SMALL_TECHNIC_WHEEL_DIAMETER, WHEEL_BASE)
print("Drive base default settings (speed, accel, turn rate, turn accel):", DRIVE_BASE.settings())
print("Drive speed limit", DRIVE_BASE.distance_control.limits())
print("Drive turn limit", DRIVE_BASE.heading_control.limits())
LATTACH = Motor(Port.E, Direction.CLOCKWISE)
RATTACH = Motor(Port.F, Direction.CLOCKWISE)
LMOTOR = left_motor
RMOTOR = right_motor
DB = DRIVE_BASE
RA = RATTACH
LA = LATTACH


(TOP_DRIVE_SPEED, TOP_DRIVE_ACCEL, TOP_DRIVE_TORQUE) = DRIVE_BASE.distance_control.limits()
(TOP_TURN_SPEED, TOP_TURN_ACCEL, TOP_TURN_TORQUE) = DRIVE_BASE.heading_control.limits()

ratio_to_top = .5
ratio_to_top_turn = 0.5
DEF_SPEED = int(ratio_to_top * TOP_DRIVE_SPEED)
DEF_ACCEL = int(ratio_to_top * TOP_DRIVE_ACCEL)
DEF_TURN_SPEED = int(ratio_to_top_turn * TOP_TURN_SPEED)
DEF_TURN_ACCEL = int(ratio_to_top_turn * TOP_TURN_ACCEL)

print("DEFAULTS (speed, accel, turn, turn accel): ", DEF_SPEED, DEF_ACCEL, DEF_TURN_SPEED, DEF_TURN_ACCEL)
pivot_radius = int(WHEEL_BASE/2)

that gives us values like for the two medium motors from Spike Prime.

Drive base default settings (speed, accel, turn rate, turn accel): (199, 746, 131, 589)
Drive speed limit (497, 746, 199)
Drive turn limit (393, 589, 399)
DEFAULTS (speed, accel, turn, turn accel):  248 373 196 294

I'm a bit confused by the calculation for speed limits.

I'm reading on motors.sariel.pl that the medium Spike Motor has a limit of 138RPM, that means it's 2.3 rps with a 57 mm wheel (57pi ~180 mm), wouldn't that lead to 2.3180 = 414mm speed limit?

Is the boot up process taking into account the hub voltage and then reading the rpm curve based on that? Does that mean my top speeds could be changing as my battery curve changes?

Perhaps I should do a min(SOME_CONSTANT, TOP_DRIVE_SPEED) to make it more consistent?

[laurensvalk]

The default drive speed is about half of the rated speed, but you can pick any speed that works well for your robot. (In a typical first classroom lesson, full speed isn't the ideal default.)

The target speed (speed limit isn't the best word) does not depend on battery level. It is what you choose it to be for your robot, in mm/s.