bricks/primehub/modules: Add calibration routine.

This works on Prime Hub, Technic Hub, and Essential Hub, but the instructions are still specific to Prime Hub.

Author: laurensvalk

bricks/primehub/modules/_imu_calibrate.py

@@ -1 +1,149 @@
-print("Calibrating!")
+from pybricks.hubs import ThisHub
+from pybricks.parameters import Side, Axis
+from pybricks.tools import wait, vector
+
+
+hub = ThisHub()
+
+
+def beep(freq):
+    try:
+        hub.speaker.beep(freq, 100)
+    except AttributeError:
+        # Technic hub does not have a speaker.
+        pass
+    wait(10)
+
+
+def wait_for_stationary(side):
+    while not hub.imu.stationary() or hub.imu.up() != side:
+        wait(10)
+
+
+up_sides = {
+    Side.FRONT: (0, 0),
+    Side.BACK: (1, 0),
+    Side.LEFT: (2, 1),
+    Side.RIGHT: (3, 1),
+    Side.TOP: (4, 2),
+    Side.BOTTOM: (5, 2),
+}
+
+gravity = [0] * 6
+bias = vector(0, 0, 0)
+
+STATIONARY_COUNT = 1000
+
+
+def roll_over_axis(axis, new_side):
+
+    global bias, bias_count
+
+    print("Roll it towards you, without lifting the hub up!")
+
+    angle_start = hub.imu.rotation(axis, calibrated=False)
+    while hub.imu.up() != new_side or not hub.imu.stationary():
+
+        _, _, z = hub.imu.orientation() * axis
+        if abs(z) > 0.07:
+            print(hub.imu.orientation() * axis)
+            raise RuntimeError("Lifted it!")
+        wait(100)
+
+    uncalibrated_90_deg_rotation = abs(hub.imu.rotation(axis, calibrated=False) - angle_start)
+    if abs(uncalibrated_90_deg_rotation - 90) > 10:
+        raise RuntimeError("Not 90 deg!")
+
+    print("Calibrating...")
+    beep(1000)
+
+    rotation_start = vector(
+        hub.imu.rotation(Axis.X, calibrated=False),
+        hub.imu.rotation(Axis.Y, calibrated=False),
+        hub.imu.rotation(Axis.Z, calibrated=False),
+    )
+
+    acceleration = vector(0, 0, 0)
+
+    for i in range(STATIONARY_COUNT):
+        acceleration += hub.imu.acceleration(calibrated=False)
+        bias += hub.imu.angular_velocity(calibrated=False)
+        wait(1)
+
+    acceleration /= STATIONARY_COUNT
+
+    rotation_end = vector(
+        hub.imu.rotation(Axis.X, calibrated=False),
+        hub.imu.rotation(Axis.Y, calibrated=False),
+        hub.imu.rotation(Axis.Z, calibrated=False),
+    )
+    if abs(rotation_end - rotation_start) > 1:
+        raise RuntimeError("Moved it!")
+
+    side_index, axis_index = up_sides[new_side]
+
+    # Store the gravity value for the current side being up.
+    # We will visit each side several times. We'll divide by the number
+    # of visits later.
+    gravity[side_index] += acceleration[axis_index]
+
+    beep(500)
+
+    return uncalibrated_90_deg_rotation
+
+
+calibrate_x = """
+Going to calibrate X now!
+- Put the hub on the table in front of you.
+- top side (display) facing up
+- right side (ports BDF) towards you.
+"""
+
+calibrate_y = """
+Going to calibrate Y now
+- Put the hub on the table in front of you.
+- top side (display) facing up
+- back side (speaker) towards you.
+"""
+
+calibrate_z = """
+Going to calibrate Z now!
+- Put the hub on the table in front of you.
+- front side (USB port) facing up
+- left side (ports ACE) towards you
+"""
+
+REPEAT = 2
+
+# For each 3-axis run, we will visit each side twice.
+SIDE_COUNT = REPEAT * 2
+
+
+def roll_hub(axis, message, start_side, sides):
+    print(message)
+    wait_for_stationary(start_side)
+    beep()
+    rotation = 0
+    for _ in range(REPEAT):
+        for side in sides:
+            rotation += roll_over_axis(axis, side)
+    return rotation / REPEAT
+
+
+rotation_x = roll_hub(
+    Axis.X, calibrate_x, Side.TOP, [Side.LEFT, Side.BOTTOM, Side.RIGHT, Side.TOP]
+)
+rotation_y = roll_hub(
+    Axis.Y, calibrate_y, Side.TOP, [Side.FRONT, Side.BOTTOM, Side.BACK, Side.TOP]
+)
+rotation_z = roll_hub(
+    Axis.Z, calibrate_z, Side.FRONT, [Side.RIGHT, Side.BACK, Side.LEFT, Side.FRONT]
+)
+
+hub.imu.settings(
+    angular_velocity_bias=tuple(bias / SIDE_COUNT / STATIONARY_COUNT / 6),
+    angular_velocity_scale=(rotation_x, rotation_y, rotation_z),
+    acceleration_correction=[g / SIDE_COUNT for g in gravity],
+)
+
+print("Result: ", hub.imu.settings())